HSP27 is involved in the pathogenesis of kidney tubulointerstitial fibrosis.
We hypothesized that heat shock protein 27 (HSP27), a small heat shock protein with actin-remodeling properties, is involved in the pathogenesis of kidney tubulointerstitial fibrosis. We first examined its expression in the rat unilateral ureteral obstruction (UUO) model of kidney fibrosis and epithelial-to-mesenchymal transition (EMT). Immunoblot analyses showed that UUO resulted in significant upregulation of TGF-beta1, alpha-smooth muscle actin (alpha-SMA), total and phosphorylated HSP27, and phosphorylated p38MAPK. Immunofluorescence studies showed that HSP27 costained with TGF-beta1, alpha-SMA, and E-cadherin in areas of tubulointerstitial injury. We next attempted to translate these studies in an in vitro model of EMT using rat proximal tubular epithelial cells (NRK52E). TGF-beta1 (20 ng/ml) treatment resulted in EMT (upregulation of alpha-SMA and downregulation of E-cadherin) and significant upregulation of total and phosphorylated HSP27 and p38MAPK after 3 days. Real-time PCR analyses showed that HSP27, vimentin, and fibronectin increased whereas E-cadherin mRNA levels decreased. Double-staining immunofluorescence studies showed intracytoplasmic colocalization of HSP27 with both F-actin and E-cadherin in cells undergoing EMT. HSP27 overexpression by transient transfection significantly increased E-cadherin while decreasing E-cadherin repressor Snail levels. In aggregate, these studies show that HSP27 is involved in the pathogenesis of TGF-beta1-induced EMT and chronic tubulointerstitial fibrosis. HSP27 overexpression may delay injury by upregulating E-cadherin through downregulation of Snail.
Vidyasagar
Aparna
A
Nephrology Section, Department of Medicine, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI 53713, USA.
Reese
Shannon
S
Acun
Zeki
Z
Hullett
Debra
D
Djamali
Arjang
A
D000199:Actins / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002460:Cell Line; D054338:Cell Transdifferentiation; D015536:Down-Regulation; D005355:Fibrosis; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007674:Kidney Diseases / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009363:Neoplasm Proteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015854:Up-Regulation; D014517:Ureteral Obstruction / Q000150:complications / Q000378:metabolism
D000199:Actins; D015820:Cadherins; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D053773:Transforming Growth Factor beta1; C486114:Hspb1 protein, rat; C000604450:Snai2 protein, rat; C498862:Acta2 protein, rat