title: Epithelial-to-mesenchymal transition in podocytes mediated by activation of NADPH oxidase in hyperhomocysteinemia.
abstract: The present study tested the hypothesis that hyperhomocysteinemia (hHcys) induces podocytes to undergo epithelial-to-mesenchymal transition (EMT) through the activation of NADPH oxidase (Nox). It was found that increased homocysteine (Hcys) level suppressed the expression of slit diaphragm-associated proteins, P-cadherin and zonula occludens-1 (ZO-1), in conditionally immortalized mouse podocytes, indicating the loss of their epithelial features. Meanwhile, Hcys remarkably increased the abundance of mesenchymal markers, such as fibroblast specific protein-1 (FSP-1) and α-smooth muscle actin (α-SMA). These phenotype changes in podocytes induced by Hcys were accompanied by enhanced superoxide (O⁻₂) production, which was substantially suppressed by inhibition of Nox activity. Functionally, Hcys significantly enhanced the permeability of the podocyte monolayer coupled with increased EMT, and this EMT-related increase in cell permeability could be restored by Nox inhibitors. In mice lacking gp91( phox ) (gp91(-/-)), an essential Nox subunit gene, hHcys-enhanced podocyte EMT and consequent glomerular injury were examined. In wild-type (gp91(+/+)) mice, hHcys induced by a folate-free diet markedly enhanced expression of mesenchymal markers (FSP-1 and α-SMA) but decreased expression of epithelial markers of podocytes in glomeruli, which were not observed in gp91(-/-) mouse glomeruli. Podocyte injury, glomerular sclerotic pathology, and marked albuminuria observed in gp91(+/+) mice with hHcys were all significantly attenuated in gp91(-/-) mice. These results suggest that hHcys induces EMT of podocytes through activation of Nox, which represents a novel mechanism of hHcys-associated podocyte injury.
authors.affiliation: Department of Pharmacology & Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298, USA.
authors.forename: Chun
authors.initials: C
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Xia
authors.forename: Krishna M
authors.initials: KM
authors.lastname: Boini
authors.forename: Cai-Xia
authors.initials: CX
authors.lastname: Li
authors.forename: Justine M
authors.initials: JM
authors.lastname: Abais
authors.forename: Xiao-Xue
authors.initials: XX
authors.lastname: Li
authors.forename: Laura A
authors.initials: LA
authors.lastname: Laperle
authors.forename: Pin-Lan
authors.initials: PL
authors.lastname: Li
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D007678:Kidney Glomerulus / Q000378:metabolism / Q000473:pathology; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D050199:Podocytes / Q000166:cytology / Q000473:pathology / Q000502:physiology*; D034741:RNA, Small Interfering / Q000378:metabolism; D062826:Zonula Occludens-1 Protein
chemical_list: D015415:Biomarkers; D015820:Cadherins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D034741:RNA, Small Interfering; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases