Insulin-induced phosphorylation and activation of cyclic nucleotide phosphodiesterase 3B by the serine-threonine kinase Akt.
Cyclic nucleotide phosphodiesterase (PDE) is an important regulator of the cellular concentrations of the second messengers cyclic AMP (cAMP) and cGMP. Insulin activates the 3B isoform of PDE in adipocytes in a phosphoinositide 3-kinase-dependent manner; however, downstream effectors that mediate signaling to PDE3B remain unknown. Insulin-induced phosphorylation and activation of endogenous or recombinant PDE3B in 3T3-L1 adipocytes have now been shown to be inhibited by a dominant-negative mutant of the serine-threonine kinase Akt, suggesting that Akt is necessary for insulin-induced phosphorylation and activation of PDE3B. Serine-273 of mouse PDE3B is located within a motif (RXRXXS) that is preferentially phosphorylated by Akt. A mutant PDE3B in which serine-273 was replaced by alanine was not phosphorylated either in response to insulin in intact cells or by purified Akt in vitro. In contrast, PDE3B mutants in which alanine was substituted for either serine-296 or serine-421, each of which lies within a sequence (RRXS) preferentially phosphorylated by cAMP-dependent protein kinase, were phosphorylated by Akt in vitro or in response to insulin in intact cells. Moreover, the serine-273 mutant of PDE3B was not activated by insulin when expressed in adipocytes. These results suggest that PDE3B is a physiological substrate of Akt and that Akt-mediated phosphorylation of PDE3B on serine-273 is important for insulin-induced activation of PDE3B.
Kitamura
T
T
Second Department of Internal Medicine, Kobe University School of Medicine, Chuo-ku, Kobe 650-0017, Japan.
Kitamura
Y
Y
Kuroda
S
S
Hino
Y
Y
Ando
M
M
Kotani
K
K
Konishi
H
H
Matsuzaki
H
H
Kikkawa
U
U
Ogawa
W
W
Kasuga
M
M
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000235:genetics / Q000378:metabolism*; D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D004789:Enzyme Activation; D007328:Insulin / Q000494:pharmacology*; D007527:Isoenzymes; D051379:Mice; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017354:Point Mutation; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D000099293:Protein Kinase C-lambda
D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000242:Cyclic AMP; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D007328:Insulin; D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011994:Recombinant Proteins; D000099293:Protein Kinase C-lambda; C494920:Akt1 protein, rat; C517293:Pde3b protein, mouse; C517294:Pde3b protein, rat