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Genome‐wide RNA interference screen for phosphatases that contribute to regulation of the transcription factor TonEBP/OREBP
Author(s) -
Zhou Xiaoming,
Ferraris Joan D.,
Burg Maurice B.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.1001.1
Subject(s) - small interfering rna , phosphatase , kinase , rna interference , phosphorylation , microbiology and biotechnology , biology , transcription factor , rna , gene , chemistry , biochemistry
High NaCl activates TonEBP/OREBP, resulting in increased transcription of osmoprotective genes. Regulation of protein phosphorylation is known to be involved. Some of the kinases are known, but the phosphatases are not. In the present studies we screened a genome‐wide human phosphatase siRNA library in HEK293 cells for effects on TonEBP/OREBP transcriptional activity. siRNAs against 57 phosphatases significantly alter TonEBP/OREBP transcriptional activity at 500 mosmol/kg or 290 mosmol/kg or both. At 500 mosmol/kg, 31 siRNAs increase it and 16 decrease it. At 290 mosmol/kg 15 siRNAs increase it and 4 sets decrease it. 4 of the siRNAs increase TonEBP/OREBP activity at both osmolalities, 3 decrease it and 2 have opposite effects. Also, 9 siRNAs augment it at 290 mosmol/kg, but not at 500 mosmol/kg. The phosphatases that are identified include ones previously known to affect cell cycle, cytoskeleton, or MAPKs, and metabolism of phospholipids, RNA or glucose. Among 31 siRNAs that increase TonEBP/OREBP activity at 500 mosmol/kg, we have confirmed the effect of PPP1R3C and SHP‐1 by overexpression of these proteins. Additional studies are required to decide whether the known actions of the phosphatases explain the effects on TonEBP/OREBP or whether novel mechanisms are involved. We conclude that TonEBP/OREBP is regulated by phosphatases, most of which reduce its activity. Supported by the Intramural Program of NHLBI.