Neuroprotection by neurotrophic factors and membrane depolarization is regulated by calmodulin kinase IV.
Neurotrophic factors promote motoneuron (MN) survival through increased intracellular calcium (Ca(2+)) and regulation of the phosphatidylinositol (PI) 3-kinase/protein kinase B (PKB) pathway by calmodulin (CaM). Activation of the PI 3-kinase/PKB pathway is one of the well established mechanisms involved in MN survival. The Ca(2+)/CaM complex interacts with and modulates the functionality of a large number of proteins, including serine/threonine protein kinases such as Ca(2+)/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 Ca(2+)/CaM. Finally, CaMKIV associates to the p85 subunit of PI 3-kinase in a Ca(2+)-dependent manner, suggesting a role in regulating PI 3-kinase/PKB activation.
Pérez-García
M José
MJ
Cell Signaling and Apoptosis Group, Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina and Hospital Universitari Arnau de Vilanova, Universitat de Lleida, Montserrat Roig, 2, 25008-Lleida, Spain.
Gou-Fabregas
Myriam
M
de Pablo
Yolanda
Y
Llovera
Marta
M
Comella
Joan X
JX
Soler
Rosa M
RM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002645:Chickens; D017931:DNA Primers; D004625:Embryo, Nonmammalian; D004789:Enzyme Activation; D006801:Humans; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009414:Nerve Growth Factors / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D009414:Nerve Growth Factors; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4