Insulin and TNF alpha induce expression of the forkhead transcription factor gene Foxc2 in 3T3-L1 adipocytes via PI3K and ERK 1/2-dependent pathways

Mol Endocrinol. 2002 Apr;16(4):873-83. doi: 10.1210/mend.16.4.0803.


We have recently identified the winged helix/forkhead gene Foxc2 as a key regulator of adipocyte metabolism that counteracts obesity and diet-induced insulin resistance. This study was performed to elucidate the hormonal regulation of Foxc2 in adipocytes. We find that TNF alpha and insulin induce Foxc2 mRNA in differentiated 3T3-L1 cells with the kinetics of an immediate early response (1-2 h with 100 ng/ml insulin or 5 ng/ml TNF alpha). This induction is, in both cases, attenuated by the PI3K inhibitor wortmannin as well as the MAPK kinase inhibitor PD98059. Furthermore, we show that stimulation of 3T3-L1 adipocytes with phorbol-12-myristate-13-acetate or 8-(4-chlorophenyl)thio-cAMP induces the expression of Foxc2. Interestingly, we find that the basal level of Foxc2 mRNA is down-regulated whereas hormonal responsiveness increases during differentiation of 3T3-L1 from preadipocytes to adipocytes. At the protein level, immunoblots with Foxc2 antibody demonstrated an induction of Foxc2 by insulin and TNF alpha in nuclear extracts of 3T3-L1 adipocytes. EMSA of nuclear proteins from phorbol-12-myristate-13-acetate- and TNF alpha-treated 3T3-L1 adipocytes using a forkhead consensus oligonucleotide revealed specific binding of a Foxc2/DNA complex. In conclusion, our data suggest that insulin and TNF alpha regulate the expression of Foxc2 via a PI3K- and ERK 1/2-dependent pathway in 3T3-L1 adipocytes. Also, signaling pathways downstream of PKA and PKC induce the expression of Foxc2 mRNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Adipocytes / metabolism*
  • Androstadienes / pharmacology
  • Animals
  • DNA-Binding Proteins / biosynthesis*
  • Down-Regulation
  • Enzyme Inhibitors / pharmacology
  • Flavonoids / pharmacology
  • Forkhead Transcription Factors
  • Gene Expression Regulation*
  • Humans
  • Insulin / physiology*
  • Mice
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases / metabolism*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • RNA, Messenger / metabolism
  • Tetradecanoylphorbol Acetate / pharmacology
  • Transcription Factors / biosynthesis*
  • Tumor Necrosis Factor-alpha / physiology*
  • Wortmannin


  • Androstadienes
  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • Flavonoids
  • Forkhead Transcription Factors
  • Insulin
  • RNA, Messenger
  • Transcription Factors
  • Tumor Necrosis Factor-alpha
  • mesenchyme fork head 1 protein
  • Phosphatidylinositol 3-Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • Tetradecanoylphorbol Acetate
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
  • Wortmannin