Vimentin-Ser82 as a memory phosphorylation site in astrocytes

• Published in: Genes to cells : devoted to molecular & cellular mechanisms 2006-05, Vol.11 (5), p.531-540
• Main Authors: Oguri, Takashi, Inoko, Akihito, Shima, Hiroshi, Izawa, Ichiro, Arimura, Nariko, Yamaguchi, Tomoya, Inagaki, Naoyuki, Kaibuchi, Kozo, Kikuchi, Kunimi, Inagaki, Masaki
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Animals; Astrocytes - cytology; Astrocytes - enzymology; Binding Sites; Calcium - metabolism; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; Cells, Cultured; Dinoprost - metabolism; Dinoprost - pharmacology; Immunohistochemistry; Ionomycin - metabolism; Ionomycin - pharmacology; Models, Biological; Phosphoprotein Phosphatases - metabolism; Phosphorylation; Protein Phosphatase 1; Protein Subunits - metabolism; Rats; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Serine - metabolism; Time Factors; Vimentin - metabolism
• ISSN: 1356-9597; 1365-2443
• DOI: 10.1111/j.1365-2443.2006.00961.x

In astrocytes, the PGF₂α or ionomycin treatment induces the phosphorylation at Ser38 and Ser82 of vimentin, a type III intermediate filament, by Ca²⁺/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, PP1cα 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.