Three mitogen-activated protein kinases inhibit insulin signaling by different mechanisms in 3T3-L1 adipocytes

Midori Fujishiro, Yukiko Gotoh, Hideki Katagiri, Hideyuki Sakoda, Takehide Ogihara, Motonobu Anai, Yukiko Onishi, Hiraku Ono, Miho Abe, Nobuhiro Shojima, Yasushi Fukushima, Masatoshi Kikuchi, Yoshitomo Oka, Tomoichiro Asano

Research output: Contribution to journalArticlepeer-review

107 Citations (Scopus)


TNFα, which activates three different MAPKs [ERK, p38, and jun amino terminal kinase (JNK)], also induces insulin resistance. To better understand the respective roles of these three MAPK pathways in insulin signaling and their contribution to insulin resistance, constitutively active MAPK/ERK kinase (MEK)1, MAPK kinase (MKK6), and MKK7 mutants were overexpressed in 3T3-L1 adipocytes using an adenovirus-mediated transfection procedure. The MEK1 mutant, which activates ERK, markedly down-regulated expression of the insulin receptor (IR) and its major substrates, IRS-1 and IRS-2, mRNA and protein, and in turn reduced tyrosine phosphorylation of IR as well as IRS-1 and IRS-2 and their associated phosphatidyl inositol 3-kinase (PI3K) activity. The MKK6 mutant, which activates p38, moderately inhibited IRS-1 and IRS-2 expressions and IRS-1-associated PI3K activity without exerting a significant effect on the IR. Finally, the MKK7 mutant, which activates JNK, reduced tyrosine phosphorylation of IRS-1 and IRS-2 and IRS-associated PI3K activity without affecting expression of the IR, IRS-1, or IRS-2. In the context of our earlier report showing down-regulation of glucose transporter 4 by MEK1-ERK and MKK6/3-p38, the present findings suggest that chronic activation of ERK, p38, or JNK can induce insulin resistance by affecting glucose transporter expression and insulin signaling, though via distinctly different mechanisms. The contribution of ERK is, however, the strongest.

Original languageEnglish
Pages (from-to)487-497
Number of pages11
JournalMolecular Endocrinology
Issue number3
Publication statusPublished - 2003 Mar 1

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology


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