Neural cell adhesion molecule induces intracellular signaling via multiple mechanisms of Ca2+ homeostasis.
The neural cell adhesion molecule (NCAM) plays a pivotal role in the development of the nervous system, promoting neuronal differentiation via homophilic (NCAM-NCAM) as well as heterophilic (NCAM-fibroblast growth factor receptor [FGFR]) interactions. NCAM-induced intracellular signaling has been shown to affect and be dependent on the cytoplasmic Ca2+ concentration ([Ca2+]i). However, the molecular basis of this remains unclear. In this study, we determined [Ca2+]i regulating mechanisms involved in intracellular signaling induced by NCAM. To mimic the effect of homophilic NCAM interaction on [Ca2+]i in vitro, we used a peptide derived from a homophilic binding site of NCAM, termed P2, which triggers signaling cascades similar to those activated by NCAM-NCAM interaction. We found that P2 increased [Ca2+]i in primary hippocampal neurons. This effect depended on two signaling pathways. The first pathway was associated with activation of FGFR, phospholipase Cgamma, and production of diacylglycerol, and the second pathway involved Src-family kinases. Moreover, NCAM-mediated Ca2+ entry required activation of nonselective cation and T-type voltage-gated Ca2+ channels. These channels, together with the Src-family kinases, were also involved in neuritogenesis induced by physiological, homophilic NCAM interactions. Thus, unanticipated mechanisms of Ca2+ homeostasis are shown to be activated by NCAM and to contribute to neuronal differentiation.
Kiryushko
Darya
D
Protein Laboratory, Institute of Molecular Pathology, Panum Institute, DK-2200 Copenhagen N, Denmark. darya@plab.ku.dk
Korshunova
Irina
I
Berezin
Vladimir
V
Bock
Elisabeth
E
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D020747:Calcium Channels, T-Type / Q000187:drug effects* / Q000378:metabolism; D002454:Cell Differentiation; D003593:Cytoplasm / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006706:Homeostasis; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism; D009185:Myelin Proteins / Q000494:pharmacology*; D019006:Neural Cell Adhesion Molecules / Q000494:pharmacology*; D016501:Neurites / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051966:Phospholipase C gamma / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D019061:src-Family Kinases / Q000378:metabolism
D020747:Calcium Channels, T-Type; D004075:Diglycerides; D007473:Ion Channels; D009185:Myelin Proteins; D019006:Neural Cell Adhesion Molecules; C425263:P2 peptide; D017468:Receptors, Fibroblast Growth Factor; C491711:nonselective cation channel protein, rat; D019061:src-Family Kinases; D051966:Phospholipase C gamma; D002118:Calcium