Tonicity-responsive microRNAs contribute to the maximal induction of osmoregulatory transcription factor OREBP in response to high-NaCl hypertonicity.
Osmotic response element binding protein (OREBP) is a Rel-like transcription factor critical for cellular osmoresponses. Previous studies suggest that hypertonicity-induced accumulation of OREBP protein might be mediated by transcription activation as well as posttranscriptional mRNA stabilization or increased translation. However, the underlying mechanisms remain incompletely elucidated. Here, we report that microRNAs (miRNAs) play critical regulatory roles in hypertonicity-induced induction of OREBP. In renal medullary epithelial mIMCD3 cells, hypertonicity greatly stimulates the activity of the 3'-untranslated region of OREBP (OREBP-3'UTR). Furthermore, overexpression of OREBP-3'UTR or depletion of miRNAs by knocking-down Dicer greatly increases OREBP protein expression. On the other hand, significant alterations in miRNA expression occur rapidly in response to high NaCl exposure, with miR-200b and miR-717 being most significantly down-regulated. Moreover, increased miR-200b or miR-717 causes significant down-regulation of mRNA, protein and transcription activity of OREBP, whereas inhibition of miRNAs or disruption of the miRNA-3'UTR interactions abrogates the silencing effects. In vivo in mouse renal medulla, miR-200b and miR-717 are found to function to tune OREBP in response to renal tonicity alterations. Together, our results support the notion that miRNAs contribute to the maximal induction of OREBP to participate in cellular responses to osmotic stress in mammalian renal cells.
Huang
Weifeng
W
Ministry of Education Key Laboratory for Cell Biology and Tumor Cell Engineering and Department of Biomedical Sciences, School of Life Sciences, Xiamen University, Xiamen, China.
Liu
Huili
H
Wang
Tao
T
Zhang
Tiantian
T
Kuang
Juntao
J
Luo
Yu
Y
Chung
Stephen S M
SS
Yuan
Li
L
Yang
James Y
JY
D020413:3' Untranslated Regions; D000818:Animals; D002460:Cell Line; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D007679:Kidney Medulla / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D009994:Osmolar Concentration; D014176:Protein Biosynthesis / Q000187:drug effects; D020871:RNA Stability / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014556:Urine / Q000737:chemistry; D014882:Water-Electrolyte Balance
D020413:3' Untranslated Regions; C556308:MIRN717 microRNA, mouse; D035683:MicroRNAs; C543719:Mirn200 microRNA, mouse; D050778:NFATC Transcription Factors; D012333:RNA, Messenger; D012462:Saline Solution, Hypertonic