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Fritz D.,King Abdullah University of Science and Technology | Cai L.,GenScript INC. | Stefanovic L.,Florida State University | Stefanovic B.,Florida State University
Current Medicinal Chemistry | Year: 2011

Type I collagen is the most abundant protein in human body. Fibrosis is characterized by excessive synthesis of type I collagen in parenchymal organs. It is a leading cause of morbidity and mortality worldwide, about 45% of all natural deaths are attributable to some fibroproliferative disease. There is no cure for fibrosis. To find specific antifibrotic therapy targeting type I collagen, critical molecular interactions regulating its synthesis must be elucidated. Type I and type III collagen mRNAs have a unique sequence element at the 5' end, the 5' stem-loop. This stem-loop is not found in any other mRNA. We cloned LARP6 as the protein which binds collagen 5' stem-loop with high affinity and specificity. Mutation of the 5' stem-loop or knock down of LARP6 greatly diminishes collagen expression. Mice with mutation of the 5' stem-loop are resistant to development of liver fibrosis. LARP6 associates collagen mRNAs with filaments composed of nonmuscle myosin; disruption of these filaments abolishes synthesis of type I collagen. Thus, LARP6 dependent collagen synthesis is the specific mechanism of high collagen expression seen in fibrosis. We developed fluorescence polarization (FP) method to screen for drugs that can inhibit binding of LARP6 to 5' stem-loop RNA. FP is high when LARP6 is bound, but decreases to low levels when the binding is competed out. Thus, by measuring decrease in FP it is possible to identify chemical compounds that can dissociate LARP6 from the 5' stem-loop. The method is simple, fast and suitable for high throughput screening. © 2011 Bentham Science Publishers Ltd.

Liang G.,Molecular Therapeutics | Chen X.,Molecular Therapeutics | Aldous S.,Fibrosis and Wound Repair | Pu S.-F.,Global Pharmacovigilance and Epidemiology | And 11 more authors.
ACS Medicinal Chemistry Letters | Year: 2012

A series of compounds with an amidinothiophene P1 group and a pyrrolidinone-sulphonamide scaffold linker was identified as potent inhibitors of human kallikrein 6 by structure-based virtual screening based on the union accessible binding space of serine proteases. As the first series of potent nonmechanism-based hK6 inhibitors, they may be used as tool compounds for target validation. An X-ray structure of a representative compound complexed with hK6, resolved at a resolution of 1.88 Å, revealed that the amidinothiophene moiety bound in the S1 pocket and the pyrrolidinone-sulphonamide linker projected the aromatic tail into the S' pocket. © 2012 American Chemical Society.

Liang G.,Molecular Therapeutics | Chen X.,Molecular Therapeutics | Aldous S.,Sanofi S.A. | Pu S.-F.,Sanofi S.A. | And 5 more authors.
Bioorganic and Medicinal Chemistry Letters | Year: 2012

A series of hK6 inhibitors with a para-amidobenzylamine P1 group and a 2-hydroxybenzamide scaffold linker was discovered through virtual screening. The X-ray structure of hK6 complexed with compound 9b was determined to a resolution of 1.68 . The tertiary folding of the hK6 complexed with the inhibitor is conserved relative to the structure of the apo-protein, whereas the interaction between hK6 and the inhibitor is consistent with both the SAR and the in silico model used in the virtual screening. © 2011 Elsevier Ltd. All rights reserved.

Li J.,PharmaSeq, Inc. | Wang Z.,PharmaSeq, Inc. | Wang Z.,GenScript Corporation | Gryczynski I.,University of North Texas Health Science Center | Mandecki W.,PharmaSeq, Inc.
Analytical and Bioanalytical Chemistry | Year: 2010

The aim of this study is to improve assay sensitivity in common solid-phase bioassay configurations as the result of using silver nanoparticles. The solid phase was provided by numerically indexed, silicon-based electronic chips, microtransponders (p-Chips) that have previously been used in multiplexed assays. Assay configurations investigated included an ELISA-type immunoassay and a DNA hybridization assay. The surface of p-Chips was derivatized with the silver island film (SIF) and a polymer, and then characterized with AFM and SEM. Silver nanoparticle sizes were in the range of 100 to 200 nm. Four fluorophores were tested for fluorescence enhancement; namely, green fluorescent protein, phycoerythrin, Cy3 and Alexa Fluor 555. We consistently observed significant fluorescence enhancement and sensitivity improvement in the p-Chip-based assays: the sensitivity in the cytokine IL-6 immunoassay was 4.3 pg/ml, which represented a 25-fold increase over the method not involving a SIF; and 50 pM in the hybridization assay, a 38-fold increase. The greatest enhancement was obtained for p-Chip surfaces derivatized first with the polymer and then coated with SIF. In conclusion, we show that the SIF-p-Chip-based platform is a highly sensitive method to quantify low-abundance biomolecules in nucleic acid-based assays and immunoassays. © 2010 Springer-Verlag.

Kalwat M.A.,Indiana University | Wiseman D.A.,Indiana University | Luo W.,GenScript Corporation | Wang Z.,Indiana University | Thurmond D.C.,Indiana University
Molecular Endocrinology | Year: 2012

The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein syntaxin (Syn)4 is required for biphasic insulin secretion, although how it regulates each phase remains unclear. In a screen to identify new Syn4-interacting factors, the calcium-activated F-actin-severing protein gelsolin was revealed. Gelsolin has been previously implicated as a positive effector of insulin secretion, although a molecular mechanism to underlie this function is lacking. Toward this, our in vitro binding studies showed the Syn4-gelsolin interaction to be direct and mediated by the N-terminal Ha domain (amino acid residues 39-70) of Syn4. Syn4-gelsolin complexes formed under basal conditions and dissociated upon acute glucose or KCl stimulation; nifedipine blocked dissociation. The dissociating action of secretagogues could be mimicked by expression of the N-terminal Ha domain of Syn4 fused to green fluorescent protein (GFP) (GFP-39-70). Furthermore, GFP-39-70 expression in isolated mouse islet and clonal MIN6 β-cells initiated insulin release in the absence of appropriate stimuli. Consistent with this, the inhibitory GFP-39-70 peptide also initiated Syn4 activation in the absence of stimuli. Moreover, although MIN6 β-cells expressing the GFP-39-70 peptide maintained normal calcium influx in response to KCl, KCl-stimulated insulin secretion and the triggering pathway of insulin secretion were significantly impaired. Taken together, these data support a mechanistic model for gelsolin's role in insulin exocytosis: gelsolin clamps unsolicited soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE)-regulated exocytosis through direct association with Syn4 in the absence of appropriate stimuli, which is relieved upon stimulus-induced calcium influx to activate gelsolin and induce its dissociation from Syn4 to facilitate insulin exocytosis. © 2012 by The Endocrine Society.

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