title: Indoxyl sulfate promotes vascular smooth muscle cell calcification via the JNK/Pit-1 pathway.
abstract: We determined the effect of indoxyl sulfate (IS) on Pit-1 expression and the role of Pit-1 in IS-induced osteoblastic differentiation and calcification of vascular smooth muscle cells (VSMCs). To assess osteoblastic differentiation and Pit-1 expression, VSMCs were incubated with various concentrations of IS for different durations. Phosphonoformic acid (PFA), a competitive inhibitor of Pit-1, was used to verify the role of Pit-1. Western blot analysis and quantitative real-time polymerase chain reaction (PCR) were performed to assess Pit-1 protein and mRNA levels, respectively. To evaluate calcification, calcium content was measured. After IS treatment, we observed osteoblastic differentiation and calcification of VSMCs and up-regulation of Pit-1 expression. Moreover, the effect of IS on osteoblastic differentiation and Pit-1 expression was partly dose- and time-dependent. PFA abrogated the IS-induced osteoblastic differentiation and calcification of VSMCs to a certain extent. The c-Jun N-terminal kinase (JNK) pathway was activated after treatment with IS, whereas inhibition of the JNK pathway partially attenuated the effect of IS on both the stimulation of Pit-1 expression and calcium deposition. Our study is the first to demonstrate that IS promotes Pit-1 expression in part by activation of the JNK pathway that is involved in the mechanism of IS-induced osteoblastic differentiation and matrix mineralization.
authors.affiliation: a Department of Nephrology , Affiliated Beijing Friendship Hospital, Capital Medical University , Xi Cheng District , Beijing , China.
authors.forename: Yiru
authors.initials: Y
authors.lastname: Wu
authors.affiliation: a Department of Nephrology , Affiliated Beijing Friendship Hospital, Capital Medical University , Xi Cheng District , Beijing , China.
authors.forename: Xue
authors.initials: X
authors.lastname: Han
authors.affiliation: a Department of Nephrology , Affiliated Beijing Friendship Hospital, Capital Medical University , Xi Cheng District , Beijing , China.
authors.forename: Liyan
authors.initials: L
authors.lastname: Wang
authors.affiliation: a Department of Nephrology , Affiliated Beijing Friendship Hospital, Capital Medical University , Xi Cheng District , Beijing , China.
authors.forename: Zongli
authors.initials: Z
authors.lastname: Diao
authors.affiliation: a Department of Nephrology , Affiliated Beijing Friendship Hospital, Capital Medical University , Xi Cheng District , Beijing , China.
authors.forename: Wenhu
authors.initials: W
authors.lastname: Liu
mesh_terms: D002113:Calcification, Physiologic; D002118:Calcium / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D006801:Humans; D007200:Indican / Q000494:pharmacology*; D020935:MAP Kinase Signaling System; D009131:Muscle, Smooth, Vascular; D032389:Myocytes, Smooth Muscle / Q000187:drug effects*; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D050817:Transcription Factor Pit-1 / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C494187:POU1F1 protein, human; D012333:RNA, Messenger; D050817:Transcription Factor Pit-1; D007200:Indican; D002118:Calcium
keywords: Calcification; chronic kidney disease; indoxyl sulfate; type-III sodiumphosphate cotransporter; vascular smooth muscle cell