Dataset Information

Fluid shear stress-induced TGF-?/ALK5 signaling in renal epithelial cells is modulated by MEK1/2.

ABSTRACT: Renal tubular epithelial cells are exposed to mechanical forces due to fluid flow shear stress within the lumen of the nephron. These cells respond by activation of mechano-sensors located at the plasma membrane or the primary cilium, having crucial roles in maintenance of cellular homeostasis and signaling. In this paper, we applied fluid shear stress to study TGF-? signaling in renal epithelial cells with and without expression of the Pkd1-gene, encoding a mechano-sensor mutated in polycystic kidney disease. TGF-? signaling modulates cell proliferation, differentiation, apoptosis, and fibrotic deposition, cellular programs that are altered in renal cystic epithelia. SMAD2/3-mediated signaling was activated by fluid flow, both in wild-type and Pkd1 ^-/- cells. This was characterized by phosphorylation and nuclear accumulation of p-SMAD2/3, as well as altered expression of downstream target genes and epithelial-to-mesenchymal transition markers. This response was still present after cilia ablation. An inhibitor of upstream type-I-receptors, ALK4/ALK5/ALK7, as well as TGF-?-neutralizing antibodies effectively blocked SMAD2/3 activity. In contrast, an activin-ligand trap was ineffective, indicating that increased autocrine TGF-? signaling is involved. To study potential involvement of MAPK/ERK signaling, cells were treated with a MEK1/2 inhibitor. Surprisingly, fluid flow-induced expression of most SMAD2/3 targets was further enhanced upon MEK inhibition. We conclude that fluid shear stress induces autocrine TGF-?/ALK5-induced target gene expression in renal epithelial cells, which is partially restrained by MEK1/2-mediated signaling.

SUBMITTER: Kunnen SJ

PROVIDER: S-EPMC5425503 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Fluid shear stress-induced TGF-β/ALK5 signaling in renal epithelial cells is modulated by MEK1/2.

Kunnen Steven J SJ Leonhard Wouter N WN Semeins Cor C Hawinkels Lukas J A C LJAC Poelma Christian C Ten Dijke Peter P Bakker Astrid A Hierck Beerend P BP Peters Dorien J M DJM

Cellular and molecular life sciences : CMLS 20170206 12

Renal tubular epithelial cells are exposed to mechanical forces due to fluid flow shear stress within the lumen of the nephron. These cells respond by activation of mechano-sensors located at the plasma membrane or the primary cilium, having crucial roles in maintenance of cellular homeostasis and signaling. In this paper, we applied fluid shear stress to study TGF-β signaling in renal epithelial cells with and without expression of the Pkd1-gene, encoding a mechano-sensor mutated in polycystic ...[more]

PMID: 28168444

Similar Datasets

Project description:Cells lining the proximal tubule (PT) have unique membrane specializations that are required to maintain the high-capacity ion transport and endocytic functions of this nephron segment. PT cells in vivo acutely regulate ion transport in response to changes in glomerular filtration rate (GFR) to maintain glomerulotubular balance. PT cells in culture up-regulate endocytic capacity in response to acute changes in fluid shear stress (FSS); however, it is not known whether GFR modulates PT endocytosis to enable maximally efficient uptake of filtered proteins in vivo. Here, we show that cells cultured under continuous FSS develop an expanded apical endocytic pathway and increased endocytic capacity and lysosomal biogenesis. Furthermore, endocytic capacity in fully differentiated cells is rapidly modulated by changes in FSS. PT cells exposed to continuous FSS also acquired an extensive brush border and basolateral membrane invaginations resembling those observed in vivo. Culture under suboptimal levels of FSS led to intermediate phenotypes, suggesting a threshold effect. Cells exposed to FSS expressed higher levels of key proteins necessary for PT function, including ion transporters, receptors, and membrane-trafficking machinery, and increased adenine nucleotide levels. Inhibition of the mechanistic target of rapamycin (mTOR) using rapamycin prevented the increase in cellular energy levels, lysosomal biogenesis, and endocytic uptake, suggesting that these represent a coordinated differentiation program. In contrast, rapamycin did not prevent the FSS-induced increase in Na+/K+-ATPase levels. Our data suggest that rapid tuning of the endocytic response by changes in FSS may contribute to glomerulotubular balance in vivo. Moreover, FSS provides an essential stimulus in the differentiation of PT cells via separate pathways that up-regulate endocytosis and ion transport capacity. Variations in FSS may also contribute to the maturation of PT cells during kidney development and during repair after kidney injury.

Dataset Information

Fluid shear stress-induced TGF-?/ALK5 signaling in renal epithelial cells is modulated by MEK1/2.

Publications

Fluid shear stress-induced TGF-β/ALK5 signaling in renal epithelial cells is modulated by MEK1/2.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets