title: The Histone Methyltransferase Enzyme Enhancer of Zeste Homolog 2 Protects against Podocyte Oxidative Stress and Renal Injury in Diabetes.
abstract: Epigenetic regulation of oxidative stress is emerging as a critical mediator of diabetic nephropathy. In diabetes, oxidative damage occurs when there is an imbalance between reactive oxygen species generation and enzymatic antioxidant repair. Here, we investigated the function of the histone methyltransferase enzyme enhancer of zeste homolog 2 (EZH2) in attenuating oxidative injury in podocytes, focusing on its regulation of the endogenous antioxidant inhibitor thioredoxin interacting protein (TxnIP). Pharmacologic or genetic depletion of EZH2 augmented TxnIP expression and oxidative stress in podocytes cultured under high-glucose conditions. Conversely, EZH2 upregulation through inhibition of its regulatory microRNA, microRNA-101, downregulated TxnIP and attenuated oxidative stress. In diabetic rats, depletion of EZH2 decreased histone 3 lysine 27 trimethylation (H3K27me3), increased glomerular TxnIP expression, induced podocyte injury, and augmented oxidative stress and proteinuria. Chromatin immunoprecipitation sequencing revealed H3K27me3 enrichment at the promoter of the transcription factor Pax6, which was upregulated on EZH2 depletion and bound to the TxnIP promoter, controlling expression of its gene product. In high glucose-exposed podocytes and the kidneys of diabetic rats, the lower EZH2 expression detected coincided with upregulation of Pax6 and TxnIP. Finally, in a gene expression array, TxnIP was among seven of 30,854 genes upregulated by high glucose, EZH2 depletion, and the combination thereof. Thus, EZH2 represses the transcription factor Pax6, which controls expression of the antioxidant inhibitor TxnIP, and in diabetes, downregulation of EZH2 promotes oxidative stress. These findings expand the extent to which epigenetic processes affect the diabetic kidney to include antioxidant repair.
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Ferhan S
authors.initials: FS
authors.lastname: Siddiqi
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Syamantak
authors.initials: S
authors.lastname: Majumder
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Kerri
authors.initials: K
authors.lastname: Thai
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Moustafa
authors.initials: M
authors.lastname: Abdalla
authors.affiliation: Department of Biochemistry and Medical Genetics and George and Fay Yee Centre for Healthcare Innovation, University of Manitoba, Winnipeg, Manitoba, Canada; and.
authors.forename: Pingzhao
authors.initials: P
authors.lastname: Hu
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Advani
authors.affiliation: Electron Microscopy Research Services, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: White
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Bridgit B
authors.initials: BB
authors.lastname: Bowskill
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Giuliana
authors.initials: G
authors.lastname: Guarna
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Claudia C
authors.initials: CC
authors.lastname: Dos Santos
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada;
authors.forename: Kim A
authors.initials: KA
authors.lastname: Connelly
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada; advania@smh.ca.
authors.forename: Andrew
authors.initials: A
authors.lastname: Advani
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003928:Diabetic Nephropathies / Q000378:metabolism*; D000071221:Enhancer of Zeste Homolog 2 Protein / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018384:Oxidative Stress; D050199:Podocytes / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
chemical_list: D000071221:Enhancer of Zeste Homolog 2 Protein
keywords: diabetic nephropathy; oxidative stress; podocyte