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Mol Biol Cell May 15, 2017; 28 (10): 1389-1399.

PKC-mediated phosphorylation of nuclear lamins at a single serine residue regulates interphase nuclear size in Xenopus and mammalian cells.

Edens LJ , Dilsaver MR , Levy DL .

How nuclear size is regulated is a fundamental cell-biological question with relevance to cancers, which often exhibit enlarged nuclei. We previously reported that conventional protein kinase C (cPKC) contributes to nuclear size reductions that occur during early Xenopus development. Here we report that PKC-mediated phosphorylation of lamin B3 (LB3) contributes to this mechanism of nuclear size regulation. By mapping PKC phosphorylation sites on LB3 and testing the effects of phosphomutants in Xenopus laevis embryos, we identify the novel site S267 as being an important determinant of nuclear size. Furthermore, FRAP studies demonstrate that phosphorylation at this site increases lamina dynamics, providing a mechanistic explanation for how PKC activity influences nuclear size. We subsequently map this X. laevis LB3 phosphorylation site to a conserved site in mammalian lamin A (LA), S268. Manipulating PKC activity in cultured mammalian cells alters nuclear size, as does expression of LA-S268 phosphomutants. Taken together, these data demonstrate that PKC-mediated lamin phosphorylation is a conserved mechanism of nuclear size regulation.

PubMed ID: 28356420
PMC ID: PMC5426852
Article link: Mol Biol Cell
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: h2bc21 lmnb3 mtor ptk2

Article Images: [+] show captions
References [+] :
Abdalla, Correlation of nuclear morphometry of breast cancer in histological sections with clinicopathological features and prognosis. 2009, Pubmed