Activation of Akt/PDK signaling in macrophages upon binding of receptor-recognized forms of alpha2-macroglobulin to its cellular receptor: effect of silencing the CREB gene.
Macrophage binding of receptor-recognized forms of alpha2-macrogobulin (alpha2M*) significantly increases cAMP, CREB, and activated CREB. We have now examined the participation of the PI 3-kinase/PDK/Akt/p70s6k signaling cascade in alpha2M*-induced cellular proliferation and also studied the role of CREB in these events. Exposure of cells to alpha2M* caused an approximately 2-fold increase in CREB and its phosphorylation at Ser133, phosphorylation of the regulatory subunit of PI 3-kinase, Akt phosphorylation at Ser473 or Thr308, and phosphorylated 70s6k. Silencing of the CREB gene with dsRNA homologous in sequence to the target gene, markedly reduced the levels of CREB mRNA activation of CREB, PI 3-kinase, Akt, and p70s6k in alpha2M*-stimulated macrophages. We conclude that in murine peritoneal macrophages, alpha2M*-induced increase of cAMP is involved in cellular proliferation and this process is mediated by the PI 3-kinase signaling cascade.
Misra
U K
UK
Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Pizzo
Salvatore V
SV
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000730:Androstadienes / Q000378:metabolism; D000818:Animals; D002867:Chromones / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics* / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D020868:Gene Silencing; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D051379:Mice; D009025:Morpholines / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000502:physiology*; D000077191:Wortmannin; D000511:alpha-Macroglobulins / Q000378:metabolism*
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000730:Androstadienes; D002867:Chromones; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D021122:Protein Subunits; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D000077191:Wortmannin; D000511:alpha-Macroglobulins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one