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Hu K.,CAS Hefei Key Laboratory of Materials for Energy Conversion | Schmidt N.W.,University of California at Los Angeles | Zhu R.,CAS Hefei Key Laboratory of Materials for Energy Conversion | Jiang Y.,CAS Hefei Key Laboratory of Materials for Energy Conversion | And 8 more authors.

Polymeric synthetic mimics of antimicrobial peptides (SMAMPs) have recently demonstrated similar antimicrobial activity as natural antimicrobial peptides (AMPs) from innate immunity. This is surprising, since polymeric SMAMPs are heterogeneous in terms of chemical structure (random sequence) and conformation (random coil), in contrast to defined amino acid sequence and intrinsic secondary structure. To understand this better, we compare AMPs with a "minimal" mimic, a well-characterized family of polydisperse cationic methacrylate-based random copolymer SMAMPs. Specifically, we focus on a comparison between the quantifiable membrane curvature generating capacity, charge density, and hydrophobicity of the polymeric SMAMPs and AMPs. Synchrotron small-angle X-ray scattering (SAXS) results indicate that typical AMPs and these methacrylate SMAMPs generate similar amounts of membrane negative Gaussian curvature (NGC), which is topologically necessary for a variety of membrane-destabilizing processes. Moreover, the curvature generating ability of SMAMPs is more tolerant of changes in the lipid composition than that of natural AMPs with similar chemical groups, consistent with the lower specificity of SMAMPs. We find that, although the amount of NGC generated by these SMAMPs and AMPs are similar, the SMAMPs require significantly higher levels of hydrophobicity and cationic charge to achieve the same level of membrane deformation. We propose an explanation for these differences, which has implications for new synthetic strategies aimed at improved mimesis of AMPs. © 2013 American Chemical Society. Source

Wong J.S.,p53 Laboratory | Wong J.S.,A-Life Medical | Warbrick E.,A-Life Medical | Vojtesk B.,Masaryk Memorial Cancer Institute | And 2 more authors.

c-Met is a tyrosine receptor kinase which is activated by its ligand, the hepatocyte growth factor. Activation of c-Met leads to a wide spectrum of biological activities such as motility, angiogenesis, morphogenesis, cell survival and cell regeneration. c-Met is abnormally activated in many tumour types. Aberrant c-Met activation was found to induce tumour development, tumour cell migration and invasion, and the worst and final step in cancer progression, metastasis. In addition, c-Met activation in cells was also shown to confer resistance to apoptosis induced by UV damage or chemotherapeutic drugs. This study describes the development of monoclonal antibodies against c-Met as therapeutic molecules in cancer treatment/diagnostics. A panel of c-Met monoclonal antibodies was developed and characterised by epitope mapping, Western blotting, immunoprecipitation, agonist/antagonist effect in cell scatter assays and for their ability to recognise native c-Met by flow cytometry. We refer to these antibodies as Specifically Engaging Extracellular c-Met (seeMet). seeMet 2 and 13 bound strongly to native c-Met in flow cytometry and reduced SNU-5 cell growth. Interestingly, seeMet 2 binding was strongly reduced at 4°C when compared to 37°C. Detail mapping of the seeMet 2 epitope indicated a cryptic binding site hidden within the c-Met a-chain. Source

Goh A.M.,p53 Laboratory | Coffill C.R.,Institute of Molecular and Cell Biology | Lane D.P.,p53 Laboratory
Journal of Pathology

Mutations in the TP53 (p53) gene are present in a large fraction of human tumours, which frequently express mutant p53 proteins at high but heterogeneous levels. The clinical significance of this protein accumulation remains clouded. Mouse models bearing knock-in mutations of p53 have established that the mutant p53 proteins can drive tumour formation, invasion and metastasis through dominant negative inhibition of wild-type p53 as well as through gain of function or 'neomorphic' activities that can inhibit or activate the function of other proteins. These models have also shown that mutation alone does not confer stability, so the variable staining of mutant proteins seen in human cancers reflects tumour-specific activation of p53-stabilizing pathways. Blocking the accumulation and activity of mutant p53 proteins may thus provide novel cancer therapeutic and diagnostic targets, but their induction by chemotherapy may paradoxically limit the effectiveness of these treatments. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Source

Nirantar S.R.,p53 Laboratory | Ghadessy F.J.,p53 Laboratory

Emulsion technology has been successfully applied to the fields of next-generation high-throughput sequencing, protein engineering and clinical diagnostics. Here, we extend its scope to proteomics research by developing and characterizing a method, termed iCLIP (in vitro compartmentalized linkage of interacting partners), which enables genes encoding interacting protein pairs to be linked in a single segment of DNA. This will facilitate archiving of the interactomes from library versus library two-hybrid screens as libraries of linked DNAs. We further demonstrate the ability to interrogate a model yeast two-hybrid iCLIP library for interactants by "PCR-pulldown," using a primer specific to a gene of interest along with a universal primer. iCLIP libraries may also be subjected to high-throughput sequencing to generate interactome information. The applicability of the technique is also demonstrated in the related context of the bacterial two-hybrid system. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Goh W.,p53 Laboratory | Lane D.,p53 Laboratory | Ghadessy F.,p53 Laboratory
Cell Cycle

The p53 tumor suppressor plays a critical role in cancer biology, functioning as a transcription factor capable of directing cell fate. It interacts with specific DNA response elements (REs) to regulate the activity of target genes. We describe here a novel, non-radioactive assay to measure p53-DNA binding which involves the sequential use of in vitro transcription/ translation (IVT), immunoprecipitation and real-time PCR. The method reliably enables the detection of sequencespecific DNA binding of full-length p53 at low concentrations of physiologically relevant REs (<5 nM). Furthermore, we demonstrate multiplexing of 4 different REs in a single binding reaction. The use of IVT precludes the requirement for purified protein, enabling rapid characterization of the binding properties of p53 variants. Uniquely, it also offers the opportunity to add compounds during translation that might modulate and activate p53. When compared to prevailing protein-DNA binding assays, this method exhibits comparable or higher sensitivity, in addition to an expansive dynamic range afforded by the use of real-time PCR. A further extrapolation of its utility is demonstrated when the addition of a peptide known to activate p53 increased its binding to a consensus RE, consistent with published data. © 2010 Landes Bioscience. Source

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