Regulation of the pro-inflammatory cytokine osteopontin by GIP in adipocytes--a role for the transcription factor NFAT and phosphodiesterase 3B.
The incretin - glucose-dependent insulinotropic polypeptide (GIP) - and the pro-inflammatory cytokine osteopontin are known to have important roles in the regulation of adipose tissue functions. In this work we show that GIP stimulates lipogenesis and osteopontin expression in primary adipocytes. The GIP-induced increase in osteopontin expression was inhibited by the NFAT (the transcription factor nuclear factor of activated T-cells) inhibitor A-285222. Also, the NFAT kinase glycogen synthase kinase (GSK) 3 was upregulated by GIP. To test whether cAMP might be involved in GIP-mediated effects on osteopontin a number of strategies were used. Thus, the β3-adrenergic receptor agonist CL316,243 stimulated osteopontin expression, an effects which was mimicked by OPC3911, a specific inhibitor of phosphodiesterase 3. Furthermore, treatment of phosphodiesterase 3B knock-out mice with CL316,243 resulted in a dramatic upregulation of osteopontin in adipose tissue which was not the case in wild-type mice. In summary, we delineate mechanisms by which GIP stimulates osteopontin in adipocytes. Given the established link between osteopontin and insulin resistance, our data suggest that GIP by stimulating osteopontin expression, also could promote insulin resistance in adipocytes.
Department of Experimental Medical Sciences, Diabetes, Metabolism and Endocrinology, Biomedical Center, Lund University, Lund, Sweden.
Bilal
B
Omar
Elin
E
Banke
Emilia
E
Guirguis
Lina
L
Åkesson
Vincent
V
Manganiello
Valeriya
V
Lyssenko
Leif
L
Groop
Maria F
MF
Gomez
Eva
E
Degerman
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3 / Q000378:metabolism*; D005749:Gastric Inhibitory Polypeptide / Q000494:pharmacology / Q000502:physiology*; D007328:Insulin / Q000378:metabolism; D050155:Lipogenesis / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors / Q000502:physiology*; D053495:Osteopontin / Q000235:genetics / Q000378:metabolism*; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
C494244:A 285222; D007328:Insulin; D050778:NFATC Transcription Factors; D011720:Pyrazoles; D053495:Osteopontin; D005749:Gastric Inhibitory Polypeptide; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3