Modulation of the Ras/Raf/MEK/ERK pathway by Ca(2+), and calmodulin.
Ras activation induces a variety of cellular responses that depend on the specific activated effector, the intensity and amplitude of its activation, and the cellular type. Transient activation followed by a sustained but low signal of the Ras/Raf/MEK/ERK pathway is a common feature of cell proliferation in many systems. On the contrary, sustained, high activation is linked with either senescence or apoptosis in fibroblasts and to differentiation in neurones and PC12 cells. The temporal regulation of the pathway is relevant and not only depends on the specific receptor activated but also on the presence of diverse modulators of the pathway. We review here evidence showing that calcium (Ca(2+)) and calmodulin (CaM) are able to regulate the Ras/Raf/MEK/ERK pathway. CaM-binding proteins (CaMBPs) as Ras-GRF and CaM-dependent protein kinase IV (CaMKIV) positively modulate ERK1/2 activation induced by either NGF or membrane depolarisation in neurones. In fibroblasts, CaM binding to EGF receptor and K-Ras(B) may be involved in the downregulation of the pathway after its activation, allowing a proliferative signalling.
Agell
Neus
N
Departament de Biologia Cel.lular i Anatomia Patològica, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Facultat de Medicina. Universitat de Barcelona, C/Casanova, 143, 08036 Barcelona, Spain. agell@medicina.ub.es
Bachs
Oriol
O
Rocamora
Nati
N
Villalonga
Priam
P
D000818:Animals; D020013:Calcium Signaling; D002147:Calmodulin / Q000502:physiology*; D002148:Calmodulin-Binding Proteins / Q000502:physiology; D005347:Fibroblasts / Q000201:enzymology / Q000378:metabolism; D020935:MAP Kinase Signaling System; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009474:Neurons / Q000201:enzymology / Q000378:metabolism; D016716:PC12 Cells; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D051381:Rats
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D016283:Proto-Oncogene Proteins p21(ras)