Neurotrophic factors promote motoneuron (MN) survival through increased intracellular calcium (Ca2+) and regulation of the phosphatidylinositol (PI) 3-kinase/protein kinaseB(PKB) pathway by calmodulin (CaM). Activation of the PI 3-kinase/ PKBpathway is one of the well established mechanisms involved in MN survival. The Ca2+/CaM complex interacts with and modulates the functionality of a large number of proteins, including serine/threonine protein kinases such as Ca2+/CaM-dependent protein kinases (CaMKs). Using a primary culture of embryonic chicken spinal cord MNs, we investigated the role of CaMKIV in mediating this process. We cloned chicken CaMKIV and demonstrated its expression in purified MNs by means of reverse transcription-PCR, Western blot, and immunofluorescence. Using RNA interference, we show that endogenous CaMKIV mediates cell survival induced by neurotrophic factors or membrane depolarization. The survival effect is independent of CaMKIV kinase activity; however, CaMKIV functionality depends on the presence of Ca2+/ CaM. Finally, CaMKIV associates to the p85 subunit of PI 3-kinase in a Ca2+-dependent manner, suggesting a role in regulating PI 3-kinase/PKB activation. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc.
|Journal||Journal of Biological Chemistry|
|Publication status||Published - 15 Feb 2008|