Biochemical characterization and expression analysis of a novel EF-hand Ca2+ binding protein calmyrin2 (Cib2) in brain indicates its function in NMDA receptor mediated Ca2+ signaling.
Calmyrin2 (CaMy2, Cib2) is a novel EF-hand calcium-binding protein found recently in skeletal muscles. CaMy2 mRNA was also detected in brain, but nothing is known about CaMy2 protein localization and properties in the brain. We report cloning and characterization of CaMy2 in rat brain: its expression pattern, intracellular localization and biochemical features. CaMy2 binds Ca2+ and exhibits Ca2+/conformational switch. Moreover, CaMy2 undergoes N-myristoylation without Ca2+/myristoyl switch, is membrane-associated and localizes in neurons together with Golgi apparatus and dendrite markers. CaMy2 transcript and protein are present mainly in the hippocampus and cortex. In cultured hippocampal neurons, CaMy2 is induced upon neuronal activation. Most prominent increase in CaMy2 protein (7-fold), and mRNA (2-fold) occurs upon stimulation of NMDA receptor (NMDAR). The induction is blocked by translation inhibitors, specific antagonists of NMDAR, the Ca2+-chelator BAPTA, and inhibitors of ERK1/2 and PKC, kinases transmitting NMDAR-linked Ca2+ signal. Our results show that CaMy2 level is controlled by NMDAR and Ca2+ and suggest CaMy2 role in Ca2+ signaling underlying NMDAR activation.
Blazejczyk
Magdalena
M
Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland.
Sobczak
Adam
A
Debowska
Katarzyna
K
Wisniewska
Marta B
MB
Kirilenko
Aneta
A
Pikula
Slawomir
S
Jaworski
Jacek
J
Kuznicki
Jacek
J
Wojda
Urszula
U
D000818:Animals; D001921:Brain / Q000378:metabolism*; D019556:COS Cells; D020013:Calcium Signaling / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism; D002522:Chlorocebus aethiops; D015870:Gene Expression; D006624:Hippocampus / Q000378:metabolism; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D008297:Male; D009226:Myristates / Q000378:metabolism; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D002135:Calcium-Binding Proteins; C491604:Cib1 protein, rat; D009226:Myristates; D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate; D011994:Recombinant Proteins