Spatial patterns of Ca2+ signals define intracellular distribution of a signaling by Ca2+/Calmodulin-dependent protein kinase II.
Ca2+ plays a central role in cell signaling, and Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a major mediator of Ca2+ actions. The spatial distribution of intracellular Ca2+ signaling is not homogenous, rather it is dynamically organized, and it has been speculated that spatial patterns of Ca2+ signals may function as a form of cellular information transmitted to downstream molecules. To address this issue, we studied the intracellular distributions of the signalings by CaMKII and Ca2+ in the same astrocytes. The former was visualized by monitoring site-specific phosphorylation of a cytoskeletal protein vimentin, using site- and phosphorylation-specific antibodies, while the latter was examined by fura-2-based Ca2+ microscopy. Local Ca2+ signals induced vimentin phosphorylation by CaMKII localized in the same area. On the other hand, Ca2+ waves in astrocytes induced global phosphorylation of vimentin by CaMKII. A small population of vimentin filaments highly phosphorylated by CaMKII underwent structural alteration into short filaments at electron microscopic level. These results indicate that CaMKII transmits spatial patterns of Ca2+ signals to vimentin as cellular information. The possibility is discussed that spatial patterns of vimentin phosphorylation may be important for intracellular organization of vimentin filament networks.
Inagaki
N
N
Laboratory of Biochemistry, Aichi Cancer Center Research Institute, Chikusa-ku, Nagoya 464, Japan. ninagaki@aichi-cc.pref.aichi.jp
Goto
H
H
Ogawara
M
M
Nishi
Y
Y
Ando
S
S
Inagaki
M
M
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry; D015759:Ionomycin / Q000494:pharmacology; D016253:Microscopy, Immunoelectron; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D012694:Serine; D015398:Signal Transduction; D014746:Vimentin / Q000737:chemistry / Q000378:metabolism*
D000906:Antibodies; D010446:Peptide Fragments; D014746:Vimentin; D012694:Serine; D015759:Ionomycin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium