Phosphorylation of microtubule-associated protein STOP by calmodulin kinase II. | Phosphorylation of microtubule-associated protein STOP by calmodulin kinase II.: Phosphorylation of STOP by CaMKII
2006
Baratier, Julie | Peris, Leticia | Brocard, Jacques, S. | Gory-Fauré, Sylvie | Dufour, Fabrice | Bosc, Christophe | Fourest-Lieuvin, Anne | Blanchoin, Laurent | Salin, Paul, A. | Job, Didier | Andrieux, Annie | Organisation Fonctionnelle du Cytosquelette ; Université Joseph Fourier - Grenoble 1 (UJF)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-IFR27 | Laboratoire de physiologie cellulaire végétale (LPCV) ; Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Recherche Agronomique (INRA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG) ; Direction de Recherche Fondamentale (CEA) (DRF (CEA)) ; Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)) ; Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA) | Physio-pathologie des réseaux neuronaux du cycle veille-sommeil ; Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS) | This work was supported in part by grants from La Ligue Nationale contre le Cancer to D.J.
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Afficher plus [+] Moins [-]anglais. STOP proteins are microtubule-associated, calmodulin-regulated proteins responsible for the high degree of stabilization displayed by neuronal microtubules. STOP suppression in mice induces synaptic defects affecting both short and long term synaptic plasticity in hippocampal neurons. Interestingly, STOP has been identified as a component of synaptic structures in neurons, despite the absence of microtubules in nerve terminals, indicating the existence of mechanisms able to induce a translocation of STOP from microtubules to synaptic compartments. Here we have tested STOP phosphorylation as a candidate mechanism for STOP relocalization. We show that, both in vitro and in vivo, STOP is phosphorylated by the multifunctional enzyme calcium/calmodulin-dependent protein kinase II (CaMKII), which is a key enzyme for synaptic plasticity. This phosphorylation occurs on at least two independent sites. Phosphorylated forms of STOP do not bind microtubules in vitro and do not co-localize with microtubules in cultured differentiating neurons. Instead, phosphorylated STOP co-localizes with actin assemblies along neurites or at branching points. Correlatively, we find that STOP binds to actin in vitro. Finally, in differentiated neurons, phosphorylated STOP co-localizes with clusters of synaptic proteins, whereas unphosphorylated STOP does not. Thus, STOP phosphorylation by CaMKII may promote STOP translocation from microtubules to synaptic compartments where it may interact with actin, which could be important for STOP function in synaptic plasticity.
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