title: Effects of insulin, contraction, and phorbol esters on mitogen-activated protein kinase signaling in skeletal muscle from lean and ob/ob mice.
abstract: Effects of diverse stimuli, including insulin, muscle contraction, and phorbol 12-myristate-13-acetate (PMA), were determined on phosphorylation of mitogen-activated protein kinase (MAPK) signaling modules (c-Jun NH(2)-terminal kinase [JNK], p38 MAPK, and extracellular signal-related kinase [ERK1/2]) in skeletal muscle from lean and ob/ob mice. Insulin increased phosphorylation of JNK, p38 MAPK, and ERK1/2 in isolated extensor digitorum longus (EDL) and soleus muscle from lean mice in a time- and dose-dependent manner. Muscle contraction and PMA also elicited robust effects on these parallel MAPK modules. Insulin action on JNK, p38 MAPK, and ERK1/2 phosphorylation was significantly impaired in EDL and soleus muscle from ob/ob mice. In contrast, muscle contraction-mediated JNK, p38 MAPK, and ERK1/2 phosphorylation was preserved. PMA effects on phosphorylation of JNK and ERK1/2 were normal in ob/ob mice, whereas effects on p38 MAPK were abolished. In conclusion, insulin, contraction, and PMA activate MAPK signaling in skeletal muscle. Insulin-mediated responses on MAPK signaling are impaired in skeletal muscle from ob/ob mice, whereas the effect of contraction is generally well preserved. In addition, PMA-induced phosphorylation of JNK and ERK1/2 are preserved, whereas p38 MAPK pathways are impaired in skeletal muscle from ob/ob mice. Thus, appropriate MAPK responses can be elicited in insulin-resistant skeletal muscle via an insulin-independent mechanism.
authors.affiliation: Professor of Physiology, Department of Surgical Sciences, Section for Integrative Physiology, Karolinska Institutet, von Eulers väg 4, II, SE-171 77 Stockholm, Sweden.
authors.forename: Ying
authors.initials: Y
authors.lastname: Leng
authors.forename: Tatiana L
authors.initials: TL
authors.lastname: Steiler
authors.forename: Juleen R
authors.initials: JR
authors.lastname: Zierath
mesh_terms: D000818:Animals; D005260:Female; D007328:Insulin / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D009765:Obesity / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D010766:Phosphorylation / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D007328:Insulin; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate