Protein phosphatase inhibitor calyculin A induces hyperphosphorylation of cytokeratins and inhibits amylase exocytosis in the rat parotid acini

FEBS Letters

Kanazawa, Masaaki¹  Okumura, Kazuhiko¹  Ichida, Tokuro²  Takuma, Taishin² 

[1] Oral Surgery, School of Dentistry, Higashi Nippon Gakuen University, Tobetu, Hokkaido 061-02, Japan;Department of Oral Biochemistry, Higashi Nippon Gakuen University, Tobetu, Hokkaido 061-02, Japan

关键词: Protein phosphatase inhibitor;    Amylase secretion;    Calyculin A;    cAMP-mediated exocytosis;    Cytokeratin phosphorylation;   

DOI  :  10.1016/0014-5793(93)81467-E

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Calyculin A, a protein phosphatase inhibitor with a chemical structure completely different from that of okadaic acid, reproduced the inhibitory effect of okadaic acid on cyclic AMP-mediated amylase release from rat parotid acinar cells. Calyculin A markedly enhanced phosphorylation of cytokeratins in the cytoskeletal fraction of the cells, whereas cAMP had apparently no effect on the phosphorylation. Microscopic observations showed that parotid acini incubated with 100 nM calyculin A for 15 min had large vacuoles in the cytoplasm and conspicuous blebs on the basal plasma membrane. K252a, a nonselective protein kinase inhibitor, clearly reduced calyclin A-induced phosphorylation of cytokeratins, and it markedly blocked the inhibition of amylase release and morphological changes evoked by calyculin A. These results suggest that hyperphosphorylation of cytokeratins profoundly affects the morphology and secretory activity of parotid acinar cells.

【 授权许可】

Unknown