Vimentin-Ser82 as a memory phosphorylation site in astrocytes.
In astrocytes, the PGF(2alpha) or ionomycin treatment induces the phosphorylation at Ser38 and Ser82 of vimentin, a type III intermediate filament, by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). We found here that vimentin phospho-Ser82 was dephosphorylated much slower than phospho-Ser38. Vimentin phospho-Ser38 was dephosphorylated quickly by purified PP1 catalytic subunit (PP1c) in vitro, whereas phospho-Ser82 was insensitive to PP1c. Because PP1c directly bound to vimentin through a VxF motif (Val83-Asp84-Phe85), the PP1c active site appeared to be unable to approach phospho-Ser82, leading to the prolongation of the phosphorylation at Ser-82. In astrocytes, PP1calpha was in vivo associated with vimentin filaments. The repetitive treatment by ionomycin at a short interval resulted in the sustained elevation of Ser82 phosphorylation, leading to the marked disassembly of vimentin filaments. Taken together, these results suggest that vimentin is a novel member of binding partner of PP1c in astrocytes, and vimentin-Ser82 may act as a memory phosphorylation site.
Oguri
Takashi
T
Division of Biochemistry, Aichi Cancer Center Research Institute, Nagoya 464-8681, Japan.
Inoko
Akihito
A
Shima
Hiroshi
H
Izawa
Ichiro
I
Arimura
Nariko
N
Yamaguchi
Tomoya
T
Inagaki
Naoyuki
N
Kaibuchi
Kozo
K
Kikuchi
Kunimi
K
Inagaki
Masaki
M
D020816:Amino Acid Motifs; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000201:enzymology*; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002478:Cells, Cultured; D015237:Dinoprost / Q000378:metabolism / Q000494:pharmacology; D007150:Immunohistochemistry; D015759:Ionomycin / Q000378:metabolism / Q000494:pharmacology; D008954:Models, Biological; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D054645:Protein Phosphatase 1; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D013997:Time Factors; D014746:Vimentin / Q000378:metabolism*
D021122:Protein Subunits; D011994:Recombinant Proteins; D014746:Vimentin; D012694:Serine; D015759:Ionomycin; D015237:Dinoprost; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D002118:Calcium