Intrinsically disordered regions mediate macromolecular assembly of the Slit diaphragm proteins associated with Nephrotic syndrome
MOLECULAR SIMULATION
Authors: Narasimha, Sandeep K. Mulukala; Kar, Prajna Parimita; Vadrevu, Ramakrishna; Pasupulati, Anil K.
Abstract
The glomerular filtration barrier (GFB) of the kidney plays an instrumental role in preventing the excretion of large molecules and ensuring the formation of ultra-filtrated urine. Podocytes are essential components of GFB that provide epithelial coverage to the fine glomerular capillaries. Slit-diaphragm (SD) that forms the sole contact between adjacent foot-processes of the podocytes consists of multimeric protein assemblies. SD serves as a molecular sieve and confers size and charge-selective barrier. Nephrin, podocin, TRPC6, and CD2AP are some of the key proteins that constitute the SD. Mutations in these proteins are implicated in nephrotic syndrome and congenital nephropathies which are characterised by heavy proteinuria. The mechanism of how mutations in these proteins predispose to proteinuria is not known. Furthermore, the structural details of proteins that constitute SD are largely unknown. In this study, we built models for nephrin, CD2AP, podocin, and TRPC6 followed by docking and molecular dynamics simulations of the complex of these proteins. We speculate that the interfacial residues of SD proteins form a macromolecular complex through intrinsically disordered regions thereby conferring architectural stability to the SD, which is critical for glomerular permselectivity.
Down-regulation of SENCR promotes smooth muscle cells proliferation and migration in db/db mice through up-regulation of FoxO1 and TRPC6
BIOMEDICINE & PHARMACOTHERAPY
Authors: Zou, Zhi-qing; Xu, Juan; Li, Li; Han, Ye-shan
Abstract
Background: The inappropriate proliferation of vascular smooth muscle cells (VSMCs) plays a crucial role in the atherosclerotic process. SENCR was reported to be associated with cell migration in human smooth muscle cells. However, the regulation role of SENCR in SMCs is still not fully understood. Methods: qRT-PCR and Western blotting were performed to detect the mRNA and protein levels of SENCR, FOXO1 and TRPC6 in SMCs of db/db mice and SMCs exposed to high glucose. The regulation of SENCR on the expression of FoxO1 and TRPC6 were examined with luciferase report assays. Furthermore, we investigated the effect of SENCR on VSMCs proliferation and migration using MTT assay and cell migration assay, respectively. Results: Here, we found that SENCR was down-regulated in db/db mice and in SMCs exposed to high glucose. According to the result of luciferase assays, it was shown that SMCs knockdown enhanced the expression of FoxO1 and FoxO1 overexpression increased the expression of TRPC6. In addition, qRT-PCR revealed that SENCR overexpression reversed the effect of high glucose on mouse VSMCs proliferation and migration. Conclusion: In this study, our data indicated that down-regulation of SENCR promoted smooth muscle cells proliferation and migration in db/db mice through up-regulation of FoxO1 and TRPC6. (C) 2015 Elsevier Masson SAS. All rights reserved.