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Insulin regulation of tristetraprolin family and some related gene expression in mouse 3T3‐L1 adipocytes
Author(s) -
Cao Heping,
Anderson Richard A.
Publication year - 2007
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.21.5.a281-c
Subject(s) - tristetraprolin , messenger rna , gene expression , chemistry , microbiology and biotechnology , adipose tissue , insulin , 3t3 l1 , gene , biology , adipocyte , endocrinology , rna binding protein , biochemistry
Tristetraprolin (TTP) family of CCCH tandem zinc finger proteins (TTP/ZFP36, ZFP36L1, ZFP36L2, ZFP36L3) bind and destabilize some AU‐rich element‐containing mRNAs. TTP is a highly inducible gene but less is known about the expression of the other three homologues. We analyzed relative abundance of the TTP family mRNAs and the effect of insulin on their mRNA levels in mouse 3T3‐L1 adipocytes and macrophage RAW264.7 cells. Quantitative real‐time PCR assays showed that ZFP36L1 and ZFP36L2 genes were expressed 8 to 10‐fold higher than TTP in adipocytes, while ZFP36L2 gene was expressed in RAW cells 4 and 10‐fold higher than TTP and ZFP36L1, respectively. ZFP36L3 mRNA was detected at ~ 1% of TTP mRNA levels in the adipocytes and RAW cells. Insulin at 10 and 100 nM increased TTP mRNA levels by 5 to 7‐fold, but decreased those of ZFP36L3 by 40% in adipocytes after a 30‐min treatment and did not affect the TTP family mRNA levels in RAW cells. Immunoblotting showed that insulin induced TTP but did not affect ZFP36L1 protein levels in the adipocytes. The increased TTP protein expression, however, did not decrease the steady state mRNA levels of its putative destabilizing target COX2, but decreased those of VEGF in the adipocytes. This study demonstrated that insulin induces TTP mRNA and protein expression in adipocytes, and, for the first time, ZFP36L3 mRNA was detected in cells other than mouse placenta and extra‐embryonic tissues.