title: Glucosamine-induced Sp1 O-GlcNAcylation ameliorates hypoxia-induced SGLT dysfunction in primary cultured renal proximal tubule cells.
abstract: The aim of this study is to determine whether GlcN could recover the endoplasmic reticulum (ER) stress-induced dysfunction of Na(+) /glucose cotransporter (SGLT) in renal proximal tubule cells (PTCs) under hypoxia. With the rabbit model, the renal ischemia induced tubulointerstitial abnormalities and decreased SGLTs expression in tubular brush-border, which were recovered by GlcN. Thus, the protective mechanism of GlcN against renal ischemia was being examined by using PTCs. Hypoxia decreased the level of protein O-GlcNAc and the expression of O-GlcNAc transferase (OGT) while increased O-GlcNAcase (OGA) and these were reversed by GlcN. Hypoxia also decreased the expression of SGLTs (SGLT1 and 2) and [(14) C]-α-methyl-D-glucopyranoside (α-MG) uptake which were recovered by GlcN and PUGNAc (OGA inhibitor). Hypoxia enhanced reactive oxygen species (ROS) and then ER stress proteins, glucose-regulated protein 78 (GRP78), and C/EBP-homologous protein (CHOP). However, the expression of GRP78 increased till 6 h and then decreased whereas CHOP increased gradually. Moreover, decreased GRP78 and increased CHOP were reversed by NAC (antioxidant) and GlcN. GlcN ameliorated hypoxia-induced decrease of O-GlcNAc modification of Sp1 but OGT or Sp1 siRNAs blocked the recovery effect of GlcN on SGLT expression and α-MG uptake. In addition, hypoxia-decreased GRP78 and HIF-1α expression was reversed by GlcN but OGT siRNA or Sp1 siRNA ameliorated the effect of GlcN. When PTCs were transfected with GRP78 siRNA or HIF-1α siRNA, SGLT expression and α-MG uptake was decreased. Taken together, these data suggest that GlcN-induced O-GlcNAc modified Sp1 with stimulating GRP78 and HIF-1α activity ameliorate hypoxia-induced SGLT dysfunction in renal PTCs. J. Cell. Physiol. 229: 1557-1568, 2014. © 2014 Wiley Periodicals, Inc.
authors.affiliation: Department of Veterinary Physiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea.
authors.forename: Han Na
authors.initials: HN
authors.lastname: Suh
authors.forename: Yu Jin
authors.initials: YJ
authors.lastname: Lee
authors.forename: Mi Ok
authors.initials: MO
authors.lastname: Kim
authors.forename: Jung Min
authors.initials: JM
authors.lastname: Ryu
authors.forename: Ho Jae
authors.initials: HJ
authors.lastname: Han
mesh_terms: D058186:Acute Kidney Injury / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004195:Disease Models, Animal; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D005944:Glucosamine / Q000494:pharmacology*; D006031:Glycosylation; D006360:Heat-Shock Proteins / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007511:Ischemia / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008757:Methylglucosides / Q000378:metabolism; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D061251:Primary Cell Culture; D034622:RNA Interference; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism; D051269:Sodium-Glucose Transporter 1 / Q000378:metabolism*; D051297:Sodium-Glucose Transporter 2 / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D051742:Transcription Factor CHOP / Q000378:metabolism; D014162:Transfection; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008757:Methylglucosides; D017382:Reactive Oxygen Species; D051269:Sodium-Glucose Transporter 1; D051297:Sodium-Glucose Transporter 2; D016329:Sp1 Transcription Factor; D051742:Transcription Factor CHOP; D017351:N-Acetylglucosaminyltransferases; C449880:O-GlcNAc transferase; C110628:hexosaminidase C; D001619:beta-N-Acetylhexosaminidases; D005944:Glucosamine