News Article | May 10, 2017
HEK293 cells stably transfected with the STF plasmid encoding the firefly luciferase reporter under the control of a minimal promoter, and a concatemer of 7 LEF/TCF binding sites32, were obtained from J. Nathans. Mouse L cells stably transfected with the STF plasmid and a constitutively expressed Renilla luciferase (control reporter) were obtained from C. Kuo. L cells transfected with a mouse WNT3A expression vector to produce conditioned media were obtained from the ATCC. A375, SH-SY5Y and A549 cells were stably transfected with the BAR plasmid encoding the firefly luciferase reporter under the control of a minimal prompter and a concatemer of 12 TCF/LEF binding sites and a constitutively expressed Renilla luciferase (control reporter) using a lentiviral-based approach33. All reporter cell lines were cultured in complete DMEM medium (Gibco) supplemented with 10% FBS, 1% penicillin, streptomycin, and l-glutamine (Gibco), at 37 °C and 5% CO and cultured in the presence of antibiotics for selection of the transfected reporter plasmid. C3H10T1/2 cells were obtained from the ATCC. Human primary MSCs were obtained from Cell Applications, Inc. Mouse primary MSCs were obtained from Invitrogen. Cell lines have not been tested for mycoplasma contamination. The coding sequence of B12 containing a C-terminal 6×His-tag was cloned into the pET28 vector (Novagen) for bacterial cytoplasmic protein expression. Protein expression was performed in transformed BL21 cells, expression was induced with 0.7 mM IPTG at an OD of 0.8 for 3–4 h. Cells were pelleted, lysed by sonication in lysis buffer (20 mM HEPES, pH 7.2, 300 mM NaCl, 20 mM imidazole), and soluble fraction was applied to Ni-NTA agarose (QIAGEN). After washing the resin with lysis buffer containing 500 mM NaCl, B12 was eluted with 300 mM imidazole, and subsequently purified on a Superdex 75 size-exclusion column (GE Healthcare) equilibrated in HBS (10 mM HEPES, pH 7.2, 150 nM NaCl). XWnt8 was purified from a stably transfected Drosophila S2 cell line co-expressing XWnt8 and mouse FZD8 CRD–Fc described previously4. Cells were cultured in complete Schneider’s medium (Thermo Fisher Scientific), containing 10% FBS and supplemented with 1% l-glutamine, penicillin and streptomycin (Gibco), and expanded in Insect-Xpress medium (Lonza). A complex of XWnt8 and FZD8 CRD–Fc was captured from the conditioned media on Protein A agarose beads (Sigma). After washing with 10 column volumes of HBS, XWnt8 was eluted with HBS containing 0.1% n-dodecyl-β-d-maltoside (DDM) and 500 mM NaCl, while the FZD8 CRD–Fc remained bound to the beads. All other proteins were expressed in High Five (Trichoplusia ni) cells (Invitrogen) using the baculovirus expression system. To produce the B12-based surrogate, the coding sequences of B12, a flexible linker peptide comprising of 0, 1, 2 or 3 GSGSG-linker repeats, followed by the C-terminal domain of human DKK1 (residues 177–266), and a C-terminal 6×His-tag, were cloned into the pAcGP67A vector (BD Biosciences). To clone the scFv-based surrogate ligand, the sequence of the Vantictumab was retrieved from the published patent, reformatted into a scFv, and cloned at the N terminus of the surrogate variant containing the GSGSG linker peptide. To produce recombinant FZD CRD for crystallization, surface plasmon resonance measurements, SEC-MALS experiments and functional assays, the CRDs of human FZD1 (residues 113–182), human FZD4 (residues 42–161), human FZD5 (residues 30–150), human FZD7 (residues 36–163), human FZD8 (residues 32–151) and human FZD10 (residues 30–150), containing a C-terminal 3C protease cleavage site (LEVLFQ/GP), a biotin acceptor peptide (BAP)-tag (GLNDIFEAQKIEWHE) and a 6×His-tag were cloned into the same vector. The human FZD8 CRD used for crystallization contained only a C-terminal 6×His-tag, in addition to a Asn49Gln mutation to mutate the N-linked glycosylation site. FZD1/FZD8 CRD for inhibition assay contained a C-terminal 3C protease cleavage site, Fc-tag (constant region of human IgG), and a 6×His-tag. Human DKK1 (residues 32–266) with a C-terminal BAP-tag and 6×His-tag, and the two furin-like repeats of human RSPO2 (residues 36–143) with a N-terminal Fc-tag and a C-terminal 6×His-tag, were cloned also into the pAcGP67A vector. All proteins were secreted from High Five insect cells grown in Insect-Xpress medium, and purified using Ni-NTA affinity purification, and size-exclusion chromatography equilibrated in HBS (10 mM HEPES, pH 7.3, 150 nM NaCl). Enzymatic biotinylation was performed in 50 mM bicine, pH 8.3, 10 mM ATP, 10 mM magnesium acetate, 0.5 mM d-biotin with recombinant glutathione S-transferase (GST)-tagged BirA ligase overnight at 4 °C, and proteins were subsequently re-purified on a Superdex 75 size-exclusion column to remove excess biotin. We attempted to mimic the native Wnt–FZD lipid–protein interaction with a de novo designed protein–protein binding interface. A 13-residue alanine helix was docked against the lipid-binding cleft using Foldit34. This structural element was grafted onto a diverse set of native helical proteins using the Rosetta Epigraft35 application to discover scaffolds with compatible, shape-complementary backbones. Prototype designs were selected by interface size and optimized using RosettaScripts36 to perform side-chain redesign. 50 selected designs were further manually designed to ensure charge complementarity and non-essential mutations were reverted to the wild-type amino acid identity to maximize stability. DNA was obtained from Gen9 and screened for binding via yeast surface display as previously described with 1 μM biotinylated FZD8 CRD pre-incubated with 025 µM SAPE (Life Technologies)37. A design based on the scaffold with PDB code 2QUP, a uncharacterized four-helix bundle protein from Bacillus halodurans, demonstrated binding activity under these conditions, whereas knockout mutants Ala52Arg and Ala53Asd made using the Kunkel method38 abrogated binding, verifying that the functional interface used the predicted residues. Wild-type scaffold 2QUP did not bind, confirming that activity was specifically due to design. To improve the affinity of the original design, a full-coverage site-saturation mutagenesis library was constructed for design based on the 2QUP scaffold via the Kunkel mutagenesis method38 using forward and reverse primers containing a ‘NNK’ degenerate codon and 21-bp flanking regions (IDT). A yeast library was transformed as previously described39 and sorted for three rounds, collecting the top 1% of binders using the BD Influx cell sorter. Naive and selected libraries were prepared and sequenced, and the data was processed as previously described37 using a Miseq (Illumina) according to manufacturer protocols. The most enriched 11 mutations were identified by comparison of the selected and unselected pools of binders and were combined in a degenerate library containing all enriched and wild-type amino acid identities at each of these positions. This combination library was assembled from the oligonucleotides (IDT) listed below for a final theoretical diversity of around 800 k distinct variants. This library was amplified, transformed, and selected to convergence over five rounds, yielding the optimized variant B12. The B12–FZD8 CRD(N49Q) complex was formed by mixing purified B12 and FZD8 CRD(N49Q) in stoichiometric quantities. The complex was then treated with 1:100 (w/w) carboxypeptidase A (Sigma) overnight at 4 °C, and purified on a Superdex 75 (GE Healthcare Life Sciences) size-exclusion column equilibrated in HBS. Purified complex was concentrated to around 15 mg ml−1 for crystallization trials. Crystals were grown by hanging-drop vapour diffusion at 295 K, by mixing equal volumes of the complex and reservoir solution containing 42–49% PEG 400, 0.1 M Tris, pH 7.8–8.2, 0.2 M NaCl, or 20% PEG 3000, 0.1 M sodium citrate, pH 5.5. While the PEG 400 condition is already a cryo-protectant, the crystals grown in the PEG 3000 condition were cryoprotected in reservoir solution supplemented with 20% glycerol before flash freezing in liquid nitrogen. Crystals grew in space groups P2 (PEG 400 condition) and P2 (PEG 3000 condition), respectively, with 2 and 4 complexes in the asymmetric units. Cell dimensions are listed in Supplementary Table 1. Data were collected at beamline 8.2.2 at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. All data were indexed, integrated, and scaled with the XDS package40. The crystal structures in both space groups were solved by molecular replacement with the program PHASER41 using the structure of the FZD8 CRD (PDB code 1IJY) and the designed model of a minimal core of B12 as search models. Missing residues were manually build in COOT42 after initial rounds of refinement. Several residues at the N terminus (residues 1 to 16/17/20/21), at the C terminus (residues after 117) and several residues within loop regions were unstructured and could not been modelled. Furthermore, we observed that in both crystal forms, B12 underwent domain swapping, and one B12 molecule lent helix 3 and 2 to another B12, resulting in a closely packed B12 homodimer. The density of the loops connecting helixes 1 and 2, and 3 and 4 were clearly visible, and folded into helical turns. Yet, SEC-MALS experiments confirmed that B12 existed as a monomer in solution, and complexed FZD8 CRD with a 1:1 stoichiometry. PHENIX Refine43 was used to perform group coordinate refinement (rigid body refinement), followed by individual coordinate refinement using gradient-driven minimization applying stereo-chemical restraints, NCS restraints, and optimization of X-ray/stereochemistry weight, and individual B-factor refinement. Initial rounds of refinement were aided by restraints from the high-resolution mouse FZD8 CRD structure as a reference model. Real space refinement was performed in COOT into a likelihood-weighted SigmaA-weighted 2mF − DF map calculated in PHENIX. The final model in the P2 space group was refined to 3.20 Å with R and R values of 0.2002 and 0.2476, respectively (Supplementary Table 1). The quality of the structure was validated with MolProbity44. 99.5% of residues are in the favoured region of the Ramachandran plot, and no residue in the disallowed region. The structure within the P2 space group was refined to 2.99 Å with R and R values of 0.2253 and 0.2499, respectively, with 99.2% of residues in the favoured region of the Ramachandran plot, and no residues in the disallowed region. See Supplementary Table 1 for data and refinement statistics. Structure figures were prepared with the program PYMOL. Binding measurements were performed by surface plasmon resonance on a BIAcore T100 (GE Healthcare) and all proteins were purified on SEC before experiments. Biotinylated FZD1 CRD, FZD5 CRD, FZD7 CRD and FZD8 CRD were coupled at a low density to streptavidin on a SA sensor chip (GE Healthcare). An unrelated biotinylated protein was captured at equivalent coupling density to the control flow cells. Increasing concentrations of B12 and scFv–DKK1c were flown over the chip in HBS-P (GE Healthcare) containing 10% glycerol and 0.05% BSA at 40 μl ml−1. The chip surface was regenerated after each injection with 2 M MgCl in HBS-P or 50% ethylene glycol in HBS-P (scFv–DKK1c measurements), or 4 M MgCl in HBS-P (B12 measurements) for 60 s. Curves were reference-subtracted and all data were analysed using the Biacore T100 evaluation software version 2.0 with a 1:1 Langmuir binding model to determine the K values. To characterize the FZD-specificity of B12, the yeast display vector encoding B12 was transformed into EBY100 yeast. To induce the display of B12 on the yeast surface, cells were growing in SGCAA medium45, 46 for 2 days at 20 °C. 1 × 106 yeast cells per condition were washed with PBE (PBS, 0.5% BSA, 2 mM EDTA), and stained separately with 0.06–1,000 nM biotinylated FZD1/4/5/7/8/10 CRDs for 2 h at 4 °C. After washing twice with ice-cold PBE, bound FZD CRDs were labelled with 10 nM strepdavidin-Alexa647 for 20 min. Cells were fixed with 4% paraformaldehyde, and bound FZD CRD was analysing on an Accuri C6 flow cytometer. FZD8 fused to an N-terminal HaloTag47 and LRP6 fused to an N-terminal SNAP-tag48 were cloned into the pSEMS-26m vector (Covalys Biosciences) by cassette cloning49, 50. The template pSEMS-26m vectors had been coded with DNA sequences of the SNAP-tag or the HaloTag, respectively, together with an Igκ leader sequence (from the pDisplay vector, Invitrogen) as described previously50. The genes of full-length mouse Fzd8 or human LRP6 without the N-terminal signal sequences were inserted into pSEMS-26m via the XhoI and AscI or AscI and NotI, restriction sites, respectively. A plasmid encoding a model transmembrane protein, maltose-binding protein fused to a transmembrane domain, fused to an N-terminal HaloTag was prepared as described recently13. HeLa cells were cultivated at 37 °C, 5% CO in MEM Earle’s (Biochrom AG, FG0325) supplemented with 10% fetal calf serum and 1% nonessential amino acids. Cells were plated in 60-mm cell culture dishes to a density of 50% confluence and transfected via calcium phosphate precipitation49. 8–10 h after transfection, cells were washed twice with PBS and the medium was exchanged, supplied with 2 μM porcupine inhibitor IWP-2 for inhibiting maturation of endogenous Wnt in HeLa cells51. 24 h after transfection, cells were plated on glass coverslips pre-coated with PLL-PEG-RGD52 for reducing nonspecific binding of dyes during fluorescence labelling. After culturing for 12 h, coverslips were mounted into microscopy chambers for live-cell imaging. SNAP-tag and HaloTag were labelled by incubating cells with 50 nM benzylguanine-DY649 (SNAP-Surface 649, New England Biolabs) and 80 nM of HaloTag tetramethylrhodamine ligand (HTL-TMR, Promega) for 20 min at 37 °C. Under these conditions, effective degrees of labelling estimated from single molecule assays with a HaloTag–SNAP-tag fusion protein were ~40% for the SNAP-tag and ~25% for the HaloTag13. After washing three times with PBS, the chamber was refilled with MEM containing 2 μM IWP-2 for single-molecule fluorescence imaging. Single-molecule fluorescence imaging was carried out by using an inverted microscope (Olympus IX71) equipped with a triple-line total internal reflection (TIR) illumination condenser (Olympus) and a back-illuminated EMCCD camera (iXon DU897D, 512 × 512 pixel from Andor Technology). A 561-nm diode solid state laser (CL-561-200, CrystaLaser) and a 642-nm laser diode (Luxx 642-140, Omicron) were coupled into the microscope for excitation. Laser lights were reflected by a quad-line dichroic beam splitter (Di R405/488/561/647, Semrock) and passed through a TIRF objective (UAPO 150×/1.45, Olympus). For simultaneous dual-colour detection, a DualView microimager (Optical Insight) equipped with a 640 DCXR dichroic beamsplitter (Chroma) in combination with bandpass filters FF01-585/40 and FF01 670/30 (Semrock), respectively, was mounted in front of the camera. The overlay of the two channels was calibrated by imaging fluorescent microbeads (TetraSpeck microspheres 0.1 μm, T7279, Invitrogen), which were used for calculating a transformation matrix. After channel alignment, the deviation between the channels was below 10 nm. For single-molecule imaging, typical excitation powers of 1 mW at 561 nm and 0.7 mW at 642 nm measured at the objective were used. Time series of 150–300 frames were recorded at 30 Hz (4.8–9.6 s). An oxygen scavenging system containing 0.5 mg ml−1 glucose oxidase, 40 mg ml−1 catalase, and 5% (w/v) glucose, together with 1 μM ascorbic acid and 1 μM methyl viologene, was added to minimize photobleaching53. Receptor dimerization was initiated by incubating with 100 nM Wnt proteins or surrogates. Images were acquired after 5 min incubation in the presence of the ligands. All live-cell imaging experiments were carried out at room temperature. A 2D Gaussian mask was used for localizing single emitters54, 55. For colocalization analysis to determine the heterodimerization fraction, particle coordinates from two channels were aligned by a projective transformation (cp2tform of type ‘projective’, MATLAB 2012a) according to the transformation matrix obtained from microbead calibration measurement. Particles colocalized within a distance of 150 nm were selected. Only co-localized particles, which could be tracked for at least 10 consecutive frames (that is, molecules co-locomoting for at least 0.32 s) were accepted as receptor heterodimers or hetero-oligomers, which has been previously found to be a robust criterion for protein dimerization13. The fraction of heterodimerization or hetero-oligomerization was determined as the number of co-locomotion trajectories with respect to the number of the receptor trajectories. Since the receptor expression level of FZD8 or LRP6 was variable in the transiently transfected cells, only cells with similar receptor expression levels were considered (less than three times the excess of one subunit over the other). The smaller number of trajectories of either FZD8 or LRP6 was regarded as the limiting factor and therefore taken as a reference for calculating the heterodimerized/hetero-oligomerized fraction. Oligomerization values were not corrected for the degree of labelling. Single-molecule trajectories were reconstructed using the multi-target tracing (MTT) algorithm56. The detected trajectories were evaluated with respect to their step length distribution to determine the diffusion coefficients. For a reliable quantification of local mobilities, we estimated diffusion constants from the displacements with three frames (96 ms). Step-length histograms were obtained from all single molecule trajectories and fitted by a two-component model of Brownian diffusion, thus taking into account the intrinsic heterogeneity of protein diffusion in the plasma membrane57, 58. A bimodal probability density function p(r) was used for a nonlinear least square fit of the step-length histogram: where is the percentage of the fraction, contains the diffusion coefficient of each fraction (nδt = 96 ms). Average diffusion coefficients were determined by weighting the diffusion coefficients with the corresponding fractions. Single-molecule intensity distribution of individual diffraction-limited spots was extracted from the first 50 images of the recorded time lapse image sequence, in which photobleaching of dyes was kept below 10%13. Oligomerization of receptors was evaluated by fitting the obtained single molecule intensity with a multi-component Gaussian distribution function59. To ensure a reliable analysis, monomeric receptors were first distinguished based on the observation that monomers diffused much faster than oligomers. Therefore, the characteristic intensity distribution of monomeric receptor subunits was obtained by tracking of the fast mobile fraction. Fractions of the monomer, dimer, trimer and higher oligomers were then de-convoluted from the single molecule intensity distribution, presuming that intensities of clusters were multiples of the monomer intensity distribution. Immortal cells were seeded in triplicate for each condition in 96-well plates, and stimulated with surrogates, XWnt8, WNT3A conditioned media, control proteins, or other treatments for 20–24 h. After washing cells with PBS, cells in each well were lysed in 30 μl passive lysis buffer (Promega). 10 μl per well of lysate was assayed using the Dual Luciferase Assay kit (Promega) and normalized to the Renilla luciferase signal driven constitutively by the human elongation factor-1 alpha promoter to account for cell variability. A375 BAR, SH-SY5Y BAR, L STF and HEK293 STF cells were plated at a density of 10,000–20,000 cells per well, and treatment was started after 24 h in fresh medium. A549 BAR cells were plated at a density of 5,000 cells per well in the presence of 2 μM IWP-2 (Calbiochem) to suppress endogenous Wnt secretion, and treatment was started after 48 h in fresh medium containing fresh IWP-2. To induce β-catenin accumulation, SH-SY5Y BAR cells were treated for 2 h with scFv–DKK1c, WNT3A conditioned media (positive control), B12 (negative control protein) and mock conditioned media (from untransfected L cells, negative control) at 37 °C, 5% CO . After, cells were washed twice with PBS. For β-catenin stabilization assay, cells were scraped into hypotonic lysis buffer (10 mM Tris-HCl pH 7.4, 0.2 mM MgCl , supplemented with protease inhibitors), incubated on ice for 10 min, and homogenized using a hypodermic needle. Sucrose and EDTA were added to final concentration of 0.25 M and 1 mM, respectively. For LRP6 phosphorylation assay, cells were lysed in RIPA buffer (50 mM Tris pH 8.0, 150 mM NaCl, 0.5% sodium deoxylate, 1% Triton X-100), supplemented with protease inhibitor and phosphatase inhibitor for 1 h at 4 °C. Lysates were centrifuged at 12,000g for 1 h at 4 °C. Supernatants were then diluted into SDS sample buffer. For immunoblotting, samples were resolved on a 12% Mini-PROTEAN(R)TGX precast protein gel (Bio-Rad) and transferred to a PVDF membrane. The membranes were cut horizontally approx. at the 64 kDa mark of the SeeBlue plus 2 molecular mass marker (Invitrogen). Top half of the blot was incubated with anti-β-catenin primary antibody ((D10A8)XP, rabbit, Cell Signaling 8480), LRP6 antibody ((C47E12), rabbit, Cell Signaling 3395), and P-LRP6 (S1490) antibody (rabbit, Cell Signaling 2568), and the bottom part with the anti-α-tubulin primary antibody (mouse, DM1A, Sigma) in PBS containing 0.1% Tween-20 and 5% BSA overnight at 4 °C. Blots were then washed, incubated with the corresponding secondary antibodies in the same buffer, before washing and developing using the ECL prime western blotting detection reagent (GE Healthcare). To induce β-catenin accumulation, K562 and cells were stimulated for 0, 15, 30, 45, 60, 90 and 120 min with 10 nM scFv–DKK1c, recombinant Wnt3a (R&D Systems), B12 (negative control protein) or plain complete growth medium at 37 °C, 5% CO . After, cells were washed twice with PBS, fixed with 4% PFA for 10 min at room temperature, and permeabilized in 100% methanol for at least 30 min at −80 °C. The cells were than stained with Alexa-647 conjugated anti-β-catenin antibody (L54E2) (Cell Signaling Technology, 1:100–1: 50 dilution). Fluorescence was analysed on an Accuri C6 flow cytometer. Total RNA was isolated using either TRIZOL (Invitrogen) or RNeasy plus micro kit (QIAGEN) according to manufacturer’s protocols. A total of 2 μg RNA were used to generate cDNA using the RevertAid RT kit (Life Technologies) using oligo(dT)18 mRNA primers (Life Technologies) according to manufacturer’s protocol. 12 ng of cDNA per reaction were used. qPCR was performed using SYBR Green-based detection (Applied Biosystems) according to the manufacturer’s protocol on a StepOnePlus real-time PCR system (ThermoFisher Scientific). All primers were published, or validated by us. Transcript copy numbers were normalized to GAPDH for each sample, and fold induction compared to control was calculated. The following gene-specific validated primers were used: human FZD1: F: 5′-ATCCTGTGTGCTCCTCTTTTGG-3′, R: 5′-GATTGCTTTTCTCCTCTTCTTCAC-3′; human FZD2: F: 5′-CTGGGCGAGCGTGATTGT-3′, R: 5′-GTGGTGACAGTGAAGAAGGTGGAAG-3′; human FZD3: F: 5′-TCTGTATTTTGGGTTGGAAGCA-3′, R: 5′-CGGCTCTCATTCACTATCTCTTT-3′; human FZD4: F: 5′-TGGGCACTTTTTCGGTATTC-3′, R: 5′-TGCCCACCAACAAAGACATA-3′; human FZD5: F: 5′-CCATGATTCTTTAAGGTGAGCTG-3′, R: 5′-ACTTATTCAAGACACAACGATGG-3′; human FZD6: F: 5′-CGATAGCACAGCCTGCAATA-3′, R: 5′-ACGGTGCAAGCCTTATTTTG-3′; human FZD7: F: 5-TACCATAGTGAACGAAGAGGA-3′, R: 5′-TGTCAAAGGTGGGATAAAGG-3′; human FZD8: F: 5′-ACCCAGCCCCTTTTCCTCCATT-3′, R: 5′-GTCCACCCTCCTCAGCCAAC-3′; human FZD9: F: 5′-GCTGTGACTGGAATAAACCCC, R: 5′-GCTCTGCTTACAAGAAAGACTCC-3′; human FZD10: F: 5′-CTCTTCTCTGTGCTGTACACC, R: 5′-GTCTTGGAGGTCCAAATCCA-3′; mouse Fzd1: F: 5′-GCGACGTACTGAGCGGAGTG, R: 5′-TGATGGTGCGGATGCGGAAG-3′60; mouse Fzd2: F: 5′-CTCAAGGTGCCGTCCTATCTCAG, R: GCAGCACAACACCGACCATG-3′60; mouse Fzd3: F: 5′-GGTGTCCCGTGGCCTGAAG-3′, R: 5′-ACGTGCAGAAAGGAATAGCCAAG-3′60; mouse Fzd4: F: 5′-GACAACTTTCACGCCGCTCATC-3′, R: 5′-CAGGCAAACCCAAATTCTCTCAG-3′60; mouse Fzd5: F: 5′-AAGCTGCCTTCGGATGACTA-3′, R: 5′-TGCACAAGTTGCTGAACTCC-3′60; mouse Fzd6: F: 5′-TGTTGGTATCTCTGCGGTCTTCTG-3′, R: 5′-CTCGGCGGCTCTCACTGATG-3′60; mouse Fzd7: F: 5′-ATATCGCCTACAACCAGACCATCC-3′, R: 5′-AAGGAACGGCACGGAGGAATG-3′60; mouse Fzd8: F: 5′-GTTCAGTCATCAAGCAGCAAGGAG-3′, R: 5′-AAGGCAGGCGACAACGACG-3′60; mouse Fzd9: F: 5′-ATGAAGACGGGAGGCACCAATAC-3′, R: 5′-TAGCAGACAATGACGCAGGTGG-3′60; mouse Fzd10: F: 5′-ATCGGCACTTCCTTCATCCTGTC-3′, R: 5′-TCTTCCAGTAGTCCATGTTGAG-3′60; human AXIN2: F: 5′-CTCCCCACCTTGAATGAAGA-3′, R: 5′-TGGCTGGTGCAAAGACATAG-3′; human GAPDH: F: 5′-TGAAGGTCGGAGTCAACGGA-3′, R: 5′-CCATTGATGACAAGCTTCCCG-3′; mouse Gapdh: F: 5′-CCCCAATGTGTCCGTCGTG-3′, R: 5′-GCCTGCTTCACCACCTTCT-3′. Differentiation of C3H10T1/2, and human and mouse primary MSCs were performed essentially as described previously61. In brief, approximately 10,000 cells cm−2 were plated in normal culture medium (αMEM + FBS + penicillin/streptomycin), and allowed to adhere overnight. The following day, the medium was replaced with osteogenic medium (αMEM, 10% FBS, 1% penicillin/streptomycin, 50 μg ml−1 ascorbic acid, 10 mM β-glycerol phosphate (βGP), and replaced every other day. To determine alkaline phosphatase enzymatic activity, cells were fixed for 10 min with 10% formalin in PH7 PBS, before incubation in NBT-BCIP solution (1-Step(tm) NBT/BCIP Substrate Solution (Thermo Fisher Scientific, 34042) for 30 min. qPCR reactions were done with the SYBR method using the following primers: human ACTB F: 5′-GTTGTCGACGACGAGCG-3′, R: 5′-GCACAGAGCCTCGCCTT-3′; human ALPL: F: 5′-GATGTGGAGTATGAGAGTGACG-3′, R: 5′-GGTCAAGGGTCAGGAGTTC-3′; mouse Alpl: F: 5′-AAGGCTTCTTCTTGCTGGTG-3′, R: 5′-GCCTTACCCTCATGATGTCC-3′; mouse Actb: F: 5′-GGAATGGGTCAGAAGGACTC-3′, R: 5′-CATGTCGTCCCAGTTGGTAA-3′; mouse Col2a1 F: 5′-GTGGACGCTCAGGAGAAACA-3′, R: 5′-TGACATGTCGATGCCAGGAC-3′. P26N, normal adult human colon organoids, were established from a tumour-free colon segment of a patient diagnosed with CRC as described18, 62, 63. CFTR-derived colorectal organoids were obtained from a patient at Wilhelmina Children’s Hospital WKZ-UMCU. Informed consent for the generation and use of these organoids for experimentation was approved by the ethical committee at University Medical Center Utrecht (UMCU) (TcBio 14-008). Human stomach organoids, derived from normal corpus and pylorus, were from patients that underwent partial or total gastrectomy at the University Medical Centre Utrecht (UMCU) and were established as described19, 64, 65. Pancreas organoids were obtained from the healthy part of the pancreas of patients undergoing surgical resection of a tumour at the University Medical Centre Utrecht Hospital (UMC) and were established as described66, 67. The liver organoids were derived from freshly isolated normal liver tissue from a patient with metastatic CRC who presented at the UMC hospital (ethical approval code TCBio 14-007) and were established as described20, 68. For the performance of 3D cultures, Matrigel (BD Biosciences) was used and overlaid with a liquid medium consisting of DMEM/F12 advanced medium (Invitrogen), supplemented with additional factors as outlined below. 2% RSPO3-CM (produced via the r-PEX protein expression platform at U-Protein Express BV), WNT3A conditioned medium (50%, produced using stably transfected L cells in the presence of DMEM/F12 advanced medium supplemented with 10% FBS), and Wnt and Wnt/RSPO2 surrogates at different concentrations were added as indicated. Single-cell suspensions of normal human organoids were cultured in duplicate or triplicate in round-bottom 96-well plates to perform a cell viability test using Cell Titer-Glo 3D (Promega). In brief, organoids were trypsinized to single-cell suspension and plated in 100 μl medium in the presence of the different reagents. 3 μM IWP-2 was added to inhibit endogenous Wnt lipidation and secretion. After 12 days, 100 μl of Cell Titer-Glo 3D was added, plates were shaken for 5 min, incubated for an additional 25 min and centrifuged before luminescence measurement. All animal experiments were conducted in accordance with procedures approved by the IACUC at Stanford University. Experiments were not randomized, the investigators were not blinded, and all samples/data were included in the analysis. Group sample sizes were chosen based on (1) previous experiments, (2) performance of statistics analysis, and (3) logistical reasons with respect to full study size, to accommodate all groups. Adenoviruses (E1 and E3 deleted, replication deficient) were constructed to express scFv–DKK1c or scFv–DKK1c–RSPO2 with an N-terminal signal peptide and C-terminal 6×His-tag (Ad-scFv–DKK1c or Ad-scFv–DKK1c–RSPO2), respectively. Adenoviruses expressing mouse IgG2α Fc (Ad-Fc), human RSPO2–Fc fusion protein (Ad-RSPO2–Fc) and mouse WNT3A (Ad-Wnt3a) were constructed and described in the companion paper by Yan et al.26 The adenoviruses were cloned, purified by CsCl gradient, and titred as previously described69. Adult C57Bl/6J mice were purchased from Taconic Biosciences. Adult C57Bl/6J mice between 8–10 weeks old were injected intravenously with a single dose of adenovirus at between 1.2 × 107 p.f.u. to 6 × 108 p.f.u. per mouse in 0.1 ml PBS. Serum expression of Ad-scFv–DKK1c or Ad-scFv–DKK1c–RSPO2 were confirmed by immunoblotting using mouse anti-6×His (Abcam ab18184, 1:2,000) or rabbit anti-6×His (Abcam ab9108, 1:1,000), respectively. All experiments used n = 4 mice per group and repeated at least twice. qRT–PCR on liver samples were performed as following. Total cDNA was prepared from each liver sample using Direct-Zol RNA miniprep kit (Zymo Research) and iScript Reverse Transcription Supermix for RT-qPCR (BIO-RAD). Gene expression was analysed by -ΔΔC or fold change (2−ΔΔCt). Unpaired Student’s t-test (two tailed) was used to analyse statistical significance. Primers for mouse Axin2 and Cyp2f2 were previously published70. Additional primers used were listed as below: For the parabiosis experiment, age- and gender-matched C57Bl/6J mice were housed together for at least 2 weeks before surgery. At 2 days before surgery, the ‘donor’ mice were injected intravenously with a single dose of adenovirus at between 1.2 × 107 pfu to 6 × 108 pfu per mouse in 0.1 ml PBS and were separated from the ‘recipient’ mice until surgery. The parabiosis surgery was performed as described previously71. The establishment of shared circulation was confirmed at day 5 after surgery by presence of adenovirus-expressed proteins in the serum of both donors and recipients. Mouse livers were collected and fixed in 4% paraformaldehyde. 5 μm paraffin-embedded sections were stained with the following antibodies after citrate antigen retrieval and blocking with 10% normal goat serum: mouse anti-glutamine synthetase antibody (Millipore MAB302, 1:200), mouse anti-PCNA (BioLegend 307902, 1:200), and rabbit anti-HNF4α (Cell Signaling 3113S, 1:500). The immunostained tissue sections were analysed and images were captured on a Zeiss Axio-Imager Z1 with ApoTome attachment. Atomic structure factors and coordinates have been deposited to the Protein Data Bank (PDB) under accession numbers 5UN5 and 5UN6. All other data are available from the corresponding author upon reasonable request.
News Article | May 10, 2017
Patients who were included in the study all had Goodpasture disease and fulfilled the following key diagnostic criteria: (1) serum anti-α3(IV)NC1 IgG by enzyme-linked immunosorbent assay (ELISA), (2) linear IgG staining of the GBM and (3) necrotizing and crescentic glomerulonephritis. HLA-DR15 typing of patients was done by monoclonal antibody staining (BIH0596, One Lambda) and flow cytometry. Blood from HLA-typed healthy humans was collected via the Australian Bone Marrow Donor Registry. HLA-DR15, HLA-DR1 and HLA-DR15/DR1 donors were molecularly typed and were excluded if they expressed DQB1*03:02, which is potentially weakly associated with susceptibility to anti-GBM disease2. Studies were approved by the Australian Bone Marrow Donor Registry and Monash Health Research Ethics Committees, and informed consent was obtained from each individual. Mouse MHCII deficient, DR15 transgenic mice and mouse MHCII deficient, DR1 transgenic mice were derived from existing HLA transgenic colonies and intercrossed so that they were on the same background as previously described4. The background was as follows: 50% C57BL/10, 43.8% C57BL/6, 6.2% DBA/2; or with an Fcgr2b−/− background: 72% C57BL/6, 25% C57BL/10 and 3% DBA/2. To generate mice transgenic for both HLA-DR15 and HLA-DR1, mice transgenic for either HLA-DR15 or HLA-DR1 were intercrossed. FcγRIIb intact HLA transgenic mice and cells were used for all experiments, except those in experimental Goodpasture disease, where Fcgr2b−/− HLA transgenic strains were used. While DR15+ mice readily break tolerance to α3(IV)NC1 when immunized with human α3 or mouse α3 , renal disease is mild4. As genetic changes in fragment crystallizable (Fc) receptors have been implicated in the development of nephritis in rodents and in humans18, Fcgr2b−/− HLA transgenic strains were used when end organ injury was an important endpoint. For in vitro experiments, cells from either male or female mice were used. For in vivo experiments both male and female mice were used, for immunization aged 8–12 weeks and for the induction of experimental Goodpasture disease aged 8–10 weeks. Experiments were approved by the Monash University Animal Ethics Committee (MMCB2011/05 and MMCB2013/21). HLA-DR15-α3 and HLA-DR1-α3 were produced in High Five insect cells (Trichoplusia ni BTI-Tn-5B1-4 cells, Invitrogen) using the baculovirus expression system essentially as described previously for HLA-DQ2/DQ8 proteins19, 20. Briefly, synthetic DNA (Integrated DNA Technologies, Iowa, USA) encoding the α- and β-chain extracellular domains of HLA-DR15 (HLA-DR1A*0101, HLA-DRB1*15:01), HLA-DR1 (HLA-DR1A*0101, HLA-DRB1*01:01) and the α3 peptide were cloned into the pZIP3 baculovirus vector19, 20. To promote correct pairing, the carboxy (C) termini of the HLA-DR15 and HLA-DR1 α- and β-chain encoded enterokinase cleavable Fos and Jun leucine zippers, respectively. The β-chains also encoded a C-terminal BirA ligase recognition sequence for biotinylation and a poly-histidine tag for purification. HLA-DR15-α3 and HLA-DR1-α3 were purified from baculovirus-infected High Five insect cell supernatants through successive steps of immobilized metal ion affinity (Ni Sepharose 6 Fast-Flow, GE Healthcare), size exclusion (S200 Superdex 16/600, GE Healthcare) and anion exchange (HiTrap Q HP, GE Healthcare) chromatography. For crystallization, the leucine zipper and associated tags were removed by enterokinase digestion (Genscript, New Jersey, USA) further purified by anion exchange chromatography, buffer exchanged into 10 mM Tris, pH 8.0, 150 mM NaCl and concentrated to 7 mg ml−1. Purified HLA-DR15-α3 and HLA-DR1-α3 proteins were buffer exchanged into 10 mM Tris pH 8.0, biotinylated using BirA ligase and tetramers assembled by addition of Streptavidin-PE (BD Biosciences) as previously described19. In mice, 107 splenocytes or cells from kidneys were digested with 5 mg ml−1 collagenase D (Roche Diagnostics, Indianapolis, Indiana, USA) and 100 mg ml−1 DNase I (Roche Diagnostics) in HBBS (Sigma-Aldrich) for 30 min at 37 °C, then filtered, erythrocytes lysed and the CD45+ leukocyte population isolated by MACS using mouse CD45 microbeads (Miltenyi Biotec); they were then surface stained with Pacific Blue-labelled anti-mouse CD4 (BD), antigen-presenting cell (APC)-Cy7-labelled anti-mouse CD8 (BioLegend) and 10 nM PE-labelled tetramer. Cells were then incubated with a Live/Dead fixable Near IR Dead Cell Stain (Thermo Scientific), permeabilized using a Foxp3 Fix/Perm Buffer Set (BioLegend) and stained with Alexa Fluor 647-labelled anti-mouse Foxp3 antibody (FJK16 s). To determine Vα2 and Vβ6 usage, cells were stained with PerCP/Cy5.5 anti-mouse Vα2 (B20.1, Biolegend) and antigen-presenting cell labelled anti-mouse Vβ6 (RR4-7, Biolegend). For each mouse a minimum of 100 cells were analysed. The tetramer+ gate was set on the basis of the CD8+ population. In humans, 3 × 107 white blood cells were surface stained with BV510-labelled anti-human CD3 (BioLegend), Pacific Blue-labelled anti-human CD4 (BioLegend), PE-Cy7-labelled anti-human CD127 (BioLegend), FITC-labelled anti-human CD25 (BioLegend) and 10 nM PE-labelled tetramer. Then, cells were incubated with a Live/Dead fixable Near IR Dead Cell Stain (Life Technologies), permeabilized using a Foxp3 Fix/Perm Buffer Set (BioLegend) and stained with Alexa Fluor 647-labelled anti-human Foxp3 antibody (150D). The tetramer+ gate was set on the basis of the CD3+CD4− population. As validation controls, we found that HLA-DR1-α3 tetramer+ cells did not bind to HLA-DR1-CLIP tetramers (data not shown). The human α3 peptide (GWISLWKGFSF), the mouse α3 peptide (DWVSLWKGFSF) and control OVA peptide (ISQAVHAAHAEINEAGR) were synthesized at >95% purity, confirmed by high-performance liquid chromatography (Mimotopes). Recombinant murine α3(IV)NC1 was generated using a baculovirus system21 and recombinant human α3(IV)NC1 expressed in HEK 293 cells22. The murine α3(IV)NC1 peptide library, which consists of 28 20-amino-acid long peptides overlapping by 12 amino acids, was synthesized as a PepSet (Mimotopes). To measure peptide specific recall responses, IFN-γ and IL-17A ELISPOTs and [3H]thymidine proliferation assays were used (Mabtech for human ELISPOTs and BD Biosciences for mouse ELISPOTs). To measure pro-inflammatory responses of HLA-DR15-α3 tetramer+ CD4+ T cells in patients with Goodpasture disease, HLA-DR15-α3 tetramer+ CD4+ T cells were enumerated then isolated from peripheral blood mononuclear cells of patients with Goodpasture disease (frozen at the time of presentation) by magnetic bead separation (Miltenyi Biotec) then co-cultured at a frequency of 400 HLA-DR15-α3 tetramer+ CD4+ T cells per well with 2 × 106 HLA-DR15-α3 tetramer-depleted mitomycin C-treated white blood cells and stimulated with either no antigens, α3 (10 μg ml−1) or whole recombinant human α3(IV)NC1 (10 μg ml−1) in supplemented RPMI media (10% male AB serum, 2 mM l-glutamine, 50 μM 2-ME, 100 U ml−1 penicillin and 0.1 mg ml−1 streptomycin) (Sigma-Aldrich). Cells were cultured for 18 h at 37 °C, 5% CO and the data expressed as numbers of IFN-γ or IL-17A spots per well. To measure pro-inflammatory responses of HLA-DR15-α3 tetramer+ CD4+ T cells in DR15+ transgenic mice, HLA-DR15-α3 tetramer+ CD4+ T cells were enumerated then isolated from pooled spleen and lymph node cells of DR15+ transgenic mice, immunized with mouse α3 10 days previously by magnetic bead separation. They were then co-cultured at a frequency of 400 HLA-DR15-α3 tetramer+ CD4+ T cells per well with 106 HLA-DR15-α3 tetramer-depleted mitomycin C-treated white blood cells and stimulated with either no antigens, mouse α3 (10 μg ml−1), human α3 (10 μg ml−1), whole recombinant mα3(IV)NC1 (10 μg ml−1) or whole recombinant hα3(IV)NC1 (10 μg ml−1) in supplemented RPMI media (10% FCS, 2 mM l-glutamine, 50 μM 2-ME, 100 U ml−1 penicillin and 0.1 mg ml−1 streptomycin). Cells were cultured for 18 h at 37 °C, 5% CO and the data expressed as numbers of IFN-γ or IL-17A spots per well. To determine the immunogenic portions of α3(IV)NC1, mice were immunized subcutaneously with peptide pools (containing α3 amino acids 1–92, 81–164, or 153–233; 10 μg per peptide per mouse), the individual peptide or in some experiments mα3 at 10 μg per mouse in Freund’s complete adjuvant (Sigma-Aldrich). Draining lymph node cells were harvested 10 days after immunization and stimulated in vitro (5 × 105 cells per well) with no antigen, peptide (10 μg ml−1) or whole α3(IV)NC1 (10 μg ml−1) in supplemented RPMI media (10% FCS, 2 mM l-glutamine, 50 μM 2-ME, 100 U ml−1 penicillin and 0.1 mg ml streptomycin). For [3H]thymidine proliferation assays, cells were cultured in triplicate for 72 h with [3H]thymidine added to culture for the last 16 h. To measure human α3 - or mouse α3 -specific responses in CD4+ T cells from naive transgenic mice or blood of healthy humans, we used a modification of a previously published protocol23. One million CD4+ T cells were cultured with 106 mitomycin-treated CD4-depleted splenocytes for 8 days in 96-well plates with or without 100 μg ml−1 of human α3 or mouse α3 . T cells were depleted from mouse cultures by sorting out CD4+CD25+ and in humans by sorting out CD4+CD25hiCD127lo cells using antibodies and a cell sorter. Cytokine secretion was detected in the cultured supernatants by cytometric bead array (BD Biosciences) or ELISA (R&D Systems). To determine proliferation, magnetically separated CD4+ T cells were labelled with CellTrace Violet (CTV; Thermo Scientific) before culture. To measure the expansion of T cells, mice were immunized with 100 μg of α3 emulsified in Freund’s complete adjuvant, then boosted 7 days later in Freund’s incomplete adjuvant. Draining lymph node cells were stained with the HLA-DR15-α3 tetramer, CD3, CD4, CXCR5, PD-1, CD8 and Live/Dead Viability dye. To determine the potency of HLA-DR1-α3 tetramer+ T cells, 106 cells per well of CD4+CD25− T effectors isolated by CD4+ magnetic beads and CD25− cell sorting from naive DR15+DR1+ mice were co-cultured with CD4+CD25+ T cells with or without depletion of HLA-DR1-α3 tetramer+ T cells from DR1+ mice at different concentrations: 0, 12.5 × 103, 25 × 103, 50 × 103 and 100 × 103 cells per well in the presence of 106 CD4-depleted mitomycin C-treated spleen and lymph node cells from DR15+DR1+mice in supplemented RPMI media (10% FCS, 2 mM l-glutamine, 50 μM 2-ME, 100 U ml−1 penicillin and 0.1 mg ml−1 streptomycin) containing 100 μg ml−1 of mouse α3 . To determine proliferation, the CD4+CD25− T effector cells were labelled with CTV before culture. Cells were cultured in triplicate for 8 days in 96-well plates. HLA transgenic mice, on an Fcgr2b−/− background, were immunized with 100 μg of α3 or mα3 subcutaneously on days 0, 7 and 14, first in Freund’s complete, and then in Freund’s incomplete, adjuvant. Mice were killed on day 42. Albuminuria was assessed in urine collected during the last 24 h by ELISA (Bethyl Laboratories) and expressed as milligrams per micromole of urine creatinine. Blood urea nitrogen and urine creatinine were measured using an autoanalyser at Monash Health. Glomerular necrosis and crescent formation were assessed on periodic acid-Schiff (PAS)-stained sections; fibrin deposition using anti-murine fibrinogen antibody (R-4025) and DAB (Sigma); CD4+ T cells, macrophages and neutrophils were detected using anti-CD4 (GK1.5), anti-CD68 (FA/11) and anti-Gr-1 (RB6-8C5) antibodies. The investigators were not blinded to allocation during experiments and outcome assessment, except in histological and immunohistochemical assessment of kidney sections. To deplete regulatory T cells, mice were injected intraperitoneally with 1 mg of an anti-CD25 monoclonal antibody (clone PC61) or rat IgG (control) 2 days before induction of disease. In these experiments, mice were randomly assigned to receive control or anti-CD25 antibodies. Individual DR15-α3 -specific CD4+ T cells were sorted into wells of a 96-well plate. Multiplex single-cell reverse transcription and PCR amplification of TCR CDR3α and CDR3β regions were performed using a panel of TRBV- and TRAV-specific oligonucleotides, as described24, 25. Briefly, mRNA was reverse transcribed in 2.5 μl using a Superscript III VILO cDNA Synthesis Kit (Thermo Fisher Scientific, Waltham, Massachusetts, USA) (containing 1× Vilo reaction mix, 1× superscript RT, 0.1% Triton X-100), and incubated at 25 °C for 10 min, 42 °C for 120 min and 85 °C for 5 min. The entire volume was then used in a 25 μl first-round PCR reaction with 1.5 U Taq DNA polymerase, 1× PCR buffer, 1.5 mM MgCl , 0.25 mM dNTPs and a mix of 25 mouse TRAV or 40 human TRAV external sense primers and a TRAC external antisense primer, along with 19 mouse TRBV or 28 human TRBV external sense primers and a TRBC external antisense primer (each at 5 pmol μl−1), using standard PCR conditions. For the second-round nested PCR, a 2.5 μl aliquot of the first-round PCR product was used in separate TRBV- and TRAV-specific PCRs, using the same reaction mix described above; however, a set of 25 mouse TRAV or 40 human TRAV internal sense primers and a TRAC internal antisense primer, or a set of 19 mouse TRBV or 28 human TRBV internal sense primers and a TRBV internal antisense primer, were used. Second-round PCR products were visualized on a gel and positive reactions were purified with ExoSAP-IT reagent. Purified products were used as template in sequencing reactions with internal TRAC or TRBC antisense primers, as described. TCR gene segments were assigned using the IMGT (International ImMunoGeneTics) database26. In mouse experiments, three mice were pooled per HLA and the number of sequences obtained were as follows. For TRAV: DR15, n = 81; DR1 n = 84; for TRBV: DR15, n = 100; DR1 n = 87; for TRAJ: DR15, n = 81; DR1 n = 84; and for TCR beta joining (TRBJ): DR15, n = 100; DR1 n = 87. Red-blood-cell-lysed splenocytes from DR1+ and DRB15+DR1+ mice were sorted on the basis of surface expression of CD4 and CD25 and being either DR1-α3 tetramer positive or negative into three groups: (1) CD4+CD25−HLA-DR1-α3 tetramer− T cells; (2) CD4+CD25+HLA-DR1-α3 tetramer− T cells; and (3) CD4+CD25+HLA-DR1-α3 tetramer+ T cells. A minimum of 1,000 cells were sorted. Immediately after sorting, the RNA was isolated and complementary DNA (cDNA) generated using a Cells to Ct Kit (Ambion) followed by a preamplification reaction using Taqman Pre Amp Master Mix (Applied Biosystems), which preamplified the following cDNAs: Il2ra, Foxp3, Ctla4, Tnfrsf18, Il7r, Sell, Pdcd1, Entpd1, Cd44, Tgfb3, Itgae, Ccr6, Lag3, Lgals1, Ikzf2, Tnfrsf25, Nrp1, Il10. The preamplified cDNA was used for RT–PCR reactions in duplicate using Taqman probes for the aforementioned genes. Each gene was expressed relative to 18S, logarithmically transformed and presented as a heat map. The Epstein-Barr-virus-transformed human B lymphoblastoid cell lines IHW09013 (SCHU, DR15-DR51-DQ6) and IHW09004 (JESTHOM, DR1-DQ5) were maintained in RPMI (Invitrogen) supplemented with 10% FCS, 50 IU ml−1 penicillin and 50 μg ml−1 streptomycin. Confirmatory tissue typing of these cells was performed by the Victorian Transplantation and Immunogenetics Service. The B-cell hybridoma LB3.1 (anti-DR) was grown in RPMI-1640 with 5% FCS at 37 °C and secreted antibody purified using protein A sepharose (BioRad). HLA-DR-presented peptides were isolated from naive DR15+Fcgr2b+/+ or DR1+Fcgr2b+/+ mice. Spleens and lymph nodes (pooled from five mice in each group) or frozen pellets of human B lymphoblastoid cell lines (triplicate samples of 109 cells) were cryogenically milled and solubilized as previously described12, 27, cleared by ultracentrifugation and MHC peptide complexes purified using LB3.1 coupled to protein A (GE Healthcare). Bound HLA complexes were eluted from each column by acidification with 10% acetic acid. The eluted mixture of peptides and HLA heavy chains was fractionated by reversed-phase high-performance liquid chromatography as previously described10. Peptide-containing fractions were analysed by nano-liquid chromatography–tandem mass spectrometry (nano-LC–MS/MS) using a ThermoFisher Q-Exactive Plus mass spectrometer (ThermoFisher Scientific, Bremen, Germany) operated as described previously10. LC–MS/MS data were searched against mouse or human proteomes (Uniprot/Swissprot v2016_11) using ProteinPilot software (SCIEX) and resulting peptide identities subjected to strict bioinformatic criteria including the use of a decoy database to calculate the false discovery rate28. A 5% false discovery rate cut-off was applied, and the filtered data set was further analysed manually to exclude redundant peptides and known contaminants as previously described29. The mass spectrometry data have been deposited in the ProteomeXchange Consortium via the PRIDE30 partner repository with the data set identifier PXD005935. Minimal core sequences found within nested sets of peptides with either N- or C-terminal extensions were extracted and aligned using MEME (http://meme.nbcr.net/meme/), where motif width was set to 9–15 and motif distribution to ‘one per sequence’31. Graphical representation of the motif was generated using IceLogo32. Crystal trials were set up at 20 °C using the hanging drop vapour diffusion method. Crystals of HLA-DR15-α3 were grown in 25% PEG 3350, 0.2 M KNO and 0.1 M Bis-Tris-propane (pH 7.5), and crystals of HLA-DR1-α3 were grown in 23% PEG 3350, 0.1 M KNO , and 0.1 M Bis-Tris-propane (pH 7.0). Crystals were washed with mother liquor supplemented with 20% ethylene glycol and flash frozen in liquid nitrogen before data collection. Data were collected using the MX1 (ref. 33) and MX2 beamlines at the Australian Synchrotron, and processed with iMosflm and Scala from the CCP4 program suite34. The structures were solved by molecular replacement in PHASER35 and refined by iterative rounds of model building using COOT36 and restrained refinement using Phenix37 (see Extended Data Table 2 for data collection and refinement statistics). No statistical methods were used to predetermine sample size. For normally distributed data, an unpaired two-tailed t-test (when comparing two groups). For non-normally distributed data, non-parametric tests (Mann–Whitney U-test for two groups or a Kruskal–Wallis test with Dunn’s multiple comparison) were used. Statistical analyses, except for TCR usage, was by GraphPad Prism (GraphPad Software). For each TCR type/region (TRAV, TRBV, TRAJ, TRBJ), we compared the TCR distribution (frequencies of different TCRs) between DR15 and DR1 using Fisher’s exact test. This was applied both to mice and to human samples. The P values associated with those TCR distributions are indicated above the pie-charts. To correct for multiple testing for individual TCRs, we used Holm’s method. *P < 0.05, **P < 0.01, ***P < 0.001. The data that support the findings of this study are available from the corresponding authors upon request. Self-peptide repertoires have been deposited in the Proteomics Identifications Database archive with the accession code PXD005935. Structural information has been deposited in the Protein Data Bank under accession numbers 5V4M and 5V4N.
News Article | May 16, 2017
HLH and MAS are potentially life threatening disorders resulting in an overactive immune response that can damage healthy tissue and organs. HLH can be inherited (primary or familial HLH), or acquired (secondary HLH). MAS is secondary to multiple auto immune disorders and prompt diagnosis of Primary HLH and inherited immune disorders is essential and can result in successful treatment of the disease. Claritas' HLH Region of Interest was developed with rheumatologists, immunologists and oncologists including Lauren Henderson, MD, MMSc, Director of the HLH/MAS workgroup at Boston Children's Hospital, and is unique because the assay includes genes associated with both familial HLH and auto-inflammatory conditions that can cause MAS. HLH/MAS joins the Claritas menu of Immunology, Neurology, and Hematology Regions of Interest, and is based on Claritas' innovative dual-capture, dual sequencing platform method unique to the industry. This "Orthogonal Approach" simultaneously confirms ~95% of all exome variants with Sanger confirmation for the remaining 5%, providing high confidence clinical results. As with all Claritas Region of Interest tests, ordering clinicians can access full exome data provided via WuXiNextCODE Health's software.* The WuXiNextCODE CSA is the world's most widely-used system for sequence-based rare disease diagnosis. CSA provides access via an always-on, harmonized knowledgebase of all major global databases and reference sets; the ability to conduct queries according to a range of modes of inheritance without specialized informatics expertise; and instant visualization of mutations in raw sequence data. More information regarding the HLH/MAS Region of Interest can be found at www.claritasgenomics.com/test/hlh-region-interest-trio-or-proband-only. For ordering information, email firstname.lastname@example.org, visit our website at claritasgenomics.com or call Client Services at (617)553-5880 / (855)373-9003 (toll free). *not available in New York Claritas Genomics was created by leading pediatric medical centers Boston Children's Hospital and Cincinnati Children's Hospital in partnership with Cerner Corp, WuXiNextCODE Genomics, and ThermoFisher Scientific to serve children affected with complex genetic disorders by providing timely and accurate results, and resolving families' long search for answers. By combining clinical expertise of the world's best pediatric specialists with innovative best in class information and genomic platform solutions, Claritas' mission is to improve patient care and enable new discoveries for pediatric precision medicine. Now is the time to integrate genomics into clinical practice to inform, guide and improve medical treatment for kids around the world. To view the original version on PR Newswire, visit:http://www.prnewswire.com/news-releases/claritas-genomics-launches-hemophagocytic-lymphohistiocytosismacrophage-activation-system-hlhmas-region-of-interest-300458806.html