title: Angiotensin AT1 receptor activation mediates high glucose-induced epithelial-mesenchymal transition in renal proximal tubular cells.
abstract: 1. Renal tubular epithelial cells can undergo epithelial to mesenchymal transition (EMT) under hyperglycaemic conditions, which is associated with renal interstitial fibrosis. Activation of the renin-angiotensin system (RAS) is involved in diabetic nephropathy. The present study investigated the positive role of angiotensin AT1 receptors in high glucose-induced EMT in cultured tubular epithelial cells. 2. A rat kidney proximal tubular epithelial cell line (NRK-52E) was used in the present study. Levels of EMT makers, namely E-cadherin and vimentin, were estimated using fluorescence immunocytochemistry, mRNA levels of angiotensinogen (AGT), angiotensin-converting enzyme (ACE) and AT1 receptors were determined by real-time polymerase chain reaction, protein levels of E-cadherin, vimentin, fibronectin, matrix metallopeptidase (MMP)-9 and phosphorylated extracellular signal-regulated kinase (ERK) 1/2 were analysed by western blotting and the concentrations of angiotensin (Ang) II and transforming growth factor (TGF)-beta1 in the culture medium were determined by enzyme immunoassay and ELISA. 3. High glucose (30 mmol/L) induced EMT and increased the synthesis of fibronectin and MMP-9. Furthermore, high glucose increased AGT, ACE and AT(1) receptor mRNA levels, as well as AngII and TGF-beta1 concentrations in the culture medium and ERK1/2 phosphorylation. Pretreatment of cells for 15 min with the AT1 receptor antagonist losartan (10(-5) mol/L) attenuated high glucose-induced increases in TGF-beta1 and ERK1/2 phosphorylation and reduced EMT, as well as the consequent synthesis of fibronectin and MMP-9. 4. The results of the present study suggest that the activated local RAS mediates high glucose-induced EMT. By activating AT1 receptors and stimulating TGF-beta1 synthesis, the elevated local RAS participates in high glucose-induced EMT and increased extracellular matrix secretion.
authors.affiliation: Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
authors.forename: Hong
authors.initials: H
authors.lastname: Xue
authors.forename: Ping
authors.initials: P
authors.lastname: Yuan
authors.forename: Jun
authors.initials: J
authors.lastname: Ni
authors.forename: Chen
authors.initials: C
authors.lastname: Yu
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Lu
mesh_terms: D000804:Angiotensin II / Q000378:metabolism; D047228:Angiotensin II Type 1 Receptor Blockers / Q000378:metabolism / Q000494:pharmacology; D000808:Angiotensinogen / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D005109:Extracellular Matrix / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D006943:Hyperglycemia / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism; D019808:Losartan / Q000378:metabolism / Q000494:pharmacology; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism*; D012084:Renin-Angiotensin System / Q000187:drug effects; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D015820:Cadherins; D005353:Fibronectins; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D053773:Transforming Growth Factor beta1; D000808:Angiotensinogen; D000804:Angiotensin II; D007703:Peptidyl-Dipeptidase A; D005947:Glucose; D019808:Losartan