title: Blocking lysophosphatidic acid receptor 1 signaling inhibits diabetic nephropathy in db/db mice.
abstract: Lysophosphatidic acid (LPA) is known to regulate various biological responses by binding to LPA receptors. The serum level of LPA is elevated in diabetes, but the involvement of LPA in the development of diabetes and its complications remains unknown. Therefore, we studied LPA signaling in diabetic nephropathy and the molecular mechanisms involved. The expression of autotaxin, an LPA synthesis enzyme, and LPA receptor 1 was significantly increased in both mesangial cells (SV40 MES13) maintained in high-glucose media and the kidney cortex of diabetic db/db mice. Increased urinary albumin excretion, increased glomerular tuft area and volume, and mesangial matrix expansion were observed in db/db mice and reduced by treatment with ki16425, a LPA receptor 1/3 antagonist. Transforming growth factor (TGF)β expression and Smad-2/3 phosphorylation were upregulated in SV40 MES13 cells by LPA stimulation or in the kidney cortex of db/db mice, and this was blocked by ki16425 treatment. LPA receptor 1 siRNA treatment inhibited LPA-induced TGFβ expression, whereas cells overexpressing LPA receptor 1 showed enhanced LPA-induced TGFβ expression. LPA treatment of SV40 MES13 cells increased phosphorylated glycogen synthase kinase (GSK)3β at Ser9 and induced translocation of sterol regulatory element-binding protein (SREBP)1 into the nucleus. Blocking GSK3β phosphorylation inhibited SREBP1 activation and consequently blocked LPA-induced TGFβ expression in SV40 MES13 cells. Phosphorylated GSK3β and nuclear SREBP1 accumulation were increased in the kidney cortex of db/db mice and ki16425 treatment blocked these pathways. Thus, LPA receptor 1 signaling increased TGFβ expression via GSK3β phosphorylation and SREBP1 activation, contributing to the development of diabetic nephropathy.
authors.affiliation: Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea; Department of Internal Medicine, Yanbian University Hospital, Yanji, Jilin Province, China.
authors.forename: Hui Ying
authors.initials: HY
authors.lastname: Li
authors.affiliation: Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea; Gachon Medical Research Institute, Gil Hospital, Incheon, Korea. Electronic address: with62@gachon.ac.kr.
authors.forename: Yoon Sin
authors.initials: YS
authors.lastname: Oh
authors.affiliation: College of Pharmacy, Gachon University, Incheon, Korea.
authors.forename: Ji-Woong
authors.initials: JW
authors.lastname: Choi
authors.affiliation: Gachon Medical Research Institute, Gil Hospital, Incheon, Korea; Division of Nephrology, Department of Internal Medicine, Gachon University School of Medicine, Incheon, Korea.
authors.forename: Ji Yong
authors.initials: JY
authors.lastname: Jung
authors.affiliation: Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea; Gachon Medical Research Institute, Gil Hospital, Incheon, Korea; College of Pharmacy, Gachon University, Incheon, Korea. Electronic address: hsjun@gachon.ac.kr.
authors.forename: Hee-Sook
authors.initials: HS
authors.lastname: Jun
mesh_terms: D000818:Animals; D002460:Cell Line; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D003928:Diabetic Nephropathies / Q000209:etiology / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control*; D004195:Disease Models, Animal; D018450:Disease Progression; D000071679:Glycogen Synthase Kinase 3 beta / Q000378:metabolism; D007555:Isoxazoles / Q000494:pharmacology*; D007672:Kidney Cortex / Q000187:drug effects* / Q000378:metabolism; D008246:Lysophospholipids / Q000378:metabolism*; D008297:Male; D008810:Mice, Inbred C57BL; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D011422:Propionates / Q000494:pharmacology*; D034622:RNA Interference; D049368:Receptors, Lysophosphatidic Acid / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1 / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D000099189:Lysophospholipase D
chemical_list: D000071679:Glycogen Synthase Kinase 3 beta; D007555:Isoxazoles; D008246:Lysophospholipids; D010727:Phosphoric Diester Hydrolases; D011422:Propionates; D049368:Receptors, Lysophosphatidic Acid; D051899:Smad2 Protein; D051900:Smad3 Protein; D051780:Sterol Regulatory Element Binding Protein 1; D016212:Transforming Growth Factor beta; D000099189:Lysophospholipase D; C477898:3-(4-(4-((1-(2-chlorophenyl)ethoxy)carbonyl amino)-3-methyl-5-isoxazolyl) benzylsulfanyl) propanoic acid; C497783:Smad2 protein, mouse; C497791:Smad3 protein, mouse; C497388:Srebf1 protein, mouse; C000626582:LPAR1 protein, mouse; C000605507:Gsk3b protein, mouse; C032881:lysophosphatidic acid
keywords: diabetic nephropathy; extracellular matrix (ECM); lysophosphatidic acid (LPA); mesangial cell; transforming growth factor–β (TGF-β)