Premium
Glycogen synthase kinase‐3 regulation of chromatin segregation and cytokinesis in mouse preimplantation embryos
Author(s) -
Acevedo Nicole,
Wang Xia,
Dunn Rodney L.,
Smith Gary D.
Publication year - 2007
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.20495
Subject(s) - biology , cytokinesis , mitosis , blastocyst , microbiology and biotechnology , gsk 3 , chromatin , phosphorylation , embryo , embryogenesis , genetics , cell division , cell , gene
Glycogen synthase kinase‐3 (GSK‐3) is a highly conserved serine/threonine protein kinase implicated in diverse cellular processes. Activity of GSK‐3 is essential for meiotic chromatin segregation in oocytes, yet expression and/or function of GSK‐3 have not been reported in mammalian preimplantation embryos. Objectives of this study were to characterize GSK‐3 protein expression/phosphorylation in mouse preimplantation embryos, to assess the effect of GSK‐3 activity inhibition on early mitotic events, and to differentiate nuclear and cytoplasmic anomalies in GSK‐3 inhibited embryos. Both GSK‐3 isoforms were expressed during embryo development, with a differential expression of α versus β. Phosphorylation of GSK‐3α/β at residues Y279/Y216 indicated constitutive activation throughout preimplantation development. Phosphorylation at N‐terminal residues S21/S9 indicated inhibition of GSK‐3α/β activity that was differentially regulated during early development; both α and β isoforms were phosphorylated during early divisions, whereas at the blastocyst stage, only β was phosphorylated. Cytoplasmic microinjection of zygotes with anti‐GSK‐3α/β antibody significantly compromised embryonic development past the two‐cell stage compared to controls. Reversibility of developmental block was tested via pharmacological inhibitors of GSK‐3, lithium chloride (LiCl) and alsterpaullone. Similar to immunoneutralization, significantly fewer zygotes cultured with either LiCl or alsterpaullone developed past the two‐cell stage compared to controls and this mitotic block was not reversible. Inhibition of GSK‐3 activity significantly compromised timing of pronuclear membrane breakdown and mitosis initiation, nuclear development, and cytokinesis. Inhibition of GSK‐3 also resulted in abnormal chromatin segregation, evidenced by incomplete karyokinesis and micronuclei formation. These results suggest that GSK‐3 activity is critical for early preimplantation embryonic development. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.