Phosphorylation of keratin 18 serine 52 regulates mother–daughter centriole engagement and microtubule nucleation by cell cycle-dependent accumulation at the centriole

• Published in: Histochemistry and cell biology Vol. 153; no. 5; pp. 307 - 321
• Main Authors: Yu, Huiping, Yang, Xinjie, Wu, Hui, Li, Chunmei, Shi, Jingwen, Xu, Bin, Mao, Jianwen
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2020; Springer Nature B.V
• Subjects: Animals; Biochemistry; Biomedical and Life Sciences; Biomedicine; Cell Biology; Cell Cycle; Cells, Cultured; Centrioles; Centrioles - metabolism; Centrosomes; Developmental Biology; HeLa Cells; Humans; Keratin; Keratin-18 - metabolism; Localization; Mice; Microtubules - metabolism; Mutants; NIH 3T3 Cells; Nucleation; Original Paper; Phosphorylation; Polymerization; Serine; Serine - metabolism; Transfection; Microtubule nucleation; Keratin 18; Centrosome; Cell cycle
• ISSN: 0948-6143; 1432-119X
• DOI: 10.1007/s00418-020-01849-x

Serine-52 (Ser52) is the major physiologic site of keratin 18 (K18) phosphorylation. Here, we report that serine-52 phosphorylated K18 (phospho-Ser52 K18) accumulated on centrosomes in a cell cycle-dependent manner. Moreover, we found that phospho-Ser52 K18 was located at the proximal end of the mother centriole. Transfection with the K18 Ser52 → Ala (K18 S52A) mutant prevented centriole localization of phospho-Ser52 K18 and resulted in separation of the mother–daughter centrioles. Inhibition of microtubule polymerization led to the disappearance of aggregated phospho-Ser52 K18 on the centrosome; removal of inhibitors resulted in reaccumulation of phospho-Ser52 K18 in microtubule-organizing centers. Transfection with a K18 S52A mutant inhibited microtubule nucleation. These results reveal a cell cycle-dependent change in centrosome localization of phospho-Ser52 k18 and strongly suggest that the phosphorylation status of Ser52 K18 of mother centrioles plays a critical role in maintaining a tight engagement between mother and daughter centrioles and also contributes to microtubule nucleation.