Linked Life Data

18337547

Source:http://linkedlifedata.com/resource/pubmed/id/18337547

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2008-5-2
pubmed:abstractText
Transforming growth factor-beta1 (TGF-beta1) is known to induce epithelial-mesenchymal transition in the kidney, a process involved in tubulointerstitial fibrosis. We hypothesized that a coactivator of the serum response factor (SRF), megakaryoblastic leukemia factor-1 (MKL1), stimulates alpha-smooth muscle actin (alpha-SMA) transcription in primary cultures of renal tubular epithelial cells (RTC), which convert into myofibroblasts on treatment with TGF-beta1. Herein, we study the effect of MKL1 expression on alpha-SMA in these cells. We demonstrate that TGF-beta1 stimulation of alpha-SMA transcription is mediated through CC(A/T)(6)-rich GG elements known to bind to SRF. These elements also mediate the MKL1 effect that dramatically activates alpha-SMA transcription in serum-free media. MKL1 fused to green fluorescent protein localizes to the nucleus and induces alpha-SMA expression regardless of treatment with TGF-beta1. Using proteasome inhibitors, we also demonstrate that the proteolytic ubiquitin pathway regulates MKL1 expression. These data indicate that MKL1 overexpression is sufficient to induce alpha-SMA expression. Inhibition of endogenous expression of MKL1 by small interfering RNA abolishes TGF-beta1 stimulation of alpha-SMA expression. Therefore, MKL1 is also absolutely required for TGF-beta1 stimulation of alpha-SMA expression. Western blot and immunofluorescence analysis show that overexpressed and endogenous MKL1 are located in the nucleus in non-stimulated RTC. Chromatin immunoprecipitation assay demonstrates that TGF-beta1 induces binding of endogenous SRF and MKL1 to the alpha-SMA promoter in chromatin. Since MKL1 constitutes a potent factor regulating alpha-SMA expression, modulation of endogenous MKL1 expression or activity may have a profound effect on myofibroblast formation and function in the kidney.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
1931-857X
pubmed:author
pubmed:issnType
Print
pubmed:volume
294
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
F1116-28
pubmed:dateRevised
2011-4-28
pubmed:meshHeading
pubmed-meshheading:18337547-Actins, pubmed-meshheading:18337547-Blotting, Western, pubmed-meshheading:18337547-Cell Nucleus, pubmed-meshheading:18337547-Cells, Cultured, pubmed-meshheading:18337547-DNA, pubmed-meshheading:18337547-DNA-Binding Proteins, pubmed-meshheading:18337547-Epithelial Cells, pubmed-meshheading:18337547-Fibroblasts, pubmed-meshheading:18337547-Green Fluorescent Proteins, pubmed-meshheading:18337547-Humans, pubmed-meshheading:18337547-Kidney, pubmed-meshheading:18337547-Kidney Tubules, pubmed-meshheading:18337547-Microscopy, Fluorescence, pubmed-meshheading:18337547-Muscle, Smooth, pubmed-meshheading:18337547-Oncogene Proteins, Fusion, pubmed-meshheading:18337547-Promoter Regions, Genetic, pubmed-meshheading:18337547-RNA, Small Interfering, pubmed-meshheading:18337547-Reverse Transcriptase Polymerase Chain Reaction, pubmed-meshheading:18337547-Transforming Growth Factor beta1
pubmed:year
2008
pubmed:articleTitle
MKL1 mediates TGF-beta1-induced alpha-smooth muscle actin expression in human renal epithelial cells.
pubmed:affiliation
Section of Nephrology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA . gerard-elberg@ouhsc.edu
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't