Casein kinase 1 (α, δ and ε) localize at the spindle poles, but may not be essential for mammalian oocyte meiotic progression

Abstract

CK1 (casein kinase 1) is a family of serine/threonine protein kinase that is ubiquitously expressed in eukaryotic organism. CK1 members are involved in the regulation of many cellular processes. Particularly, CK1 was reported to phosphorylate Rec8 subunits of cohesin complex and regulate chromosome segregation in meiosis in budding yeast and fission yeast. (1-3) Here we investigated the expression, subcellular localization and potential functions of CK1α, CK1δ and CK1ε during mouse oocyte meiotic maturation. We found that CK1α, CK1δ and CK1ε all concentrated at the spindle poles and co-localized with γ-tubulin in oocytes at both metaphase I (MI) and metaphase II (MII) stages. However, depletion of CK1 by RNAi or overexpression of wild type or kinase-dead CK1 showed no effects on either spindle organization or chromosome segregation during oocyte meiotic maturation. Thus, CK1 is not the kinase that phosphorylates Rec8 cohesin in mammalian oocytes, and CK1 may not be essential for spindle organization and meiotic progression although they localize at spindle poles.

The Role of Casein Kinase 1 in Meiosis

“…The CK1α protein expression profile was consistent with the profile of mRNA levels except for GV [33]. The protein expression level of CK1δ and CK1ε were same as CK1α, relatively low at GV stages and then gradually increased at MI and MII stages [34].…”

“…Furthermore, overexpression of exogenous CK1α, CK1δ and CK1ε, both individually and simultaneously, caused little effect on eitherthe meiosis process, spindle organization or chromosome alignment. Their report demonstrate that although CK1α, CK1δ and CK1ε were all localized to MTOCs or spindle poles, they were not the kinase responsible for Rec8 phosphorylation during mouse oocyte meiosis, indicating that CK1 was probably not essential for mouse oocyte meiotic maturation [34]. The contradictory results need further investigation.…”

Enriched endoplasmic reticulum-mitochondria interactions result in mitochondrial dysfunction and apoptosis in oocytes from obese mice

“…[Ca 2+ ] m levels were assessed using Rhod-2AM (Invitrogen/Molecular Probes, Carlsbad, CA, U.S.) according to a previous study [ 20 ]. Briefly, zona pellucid was enzymatically removed.…”

“…siRNAs were microinjected into oocytes as described previously [ 20 ]. To knockdown Itpr1 or Pacs-2 , 10 μmol/L of each siRNA smart pool (a mixture of four siRNAs) or NC siRNA (GE Healthcare Life Sciences, South Logan, UT, U.S.) was used and the microinjection was completed within 30 min.…”

CK1 inhibitor affects in vitro maturation and developmental competence of bovine oocytes

“…For the effect of CK1 on oocyte meiosis, it had been claimed that inhibiting the expression of CK1 would lead to the failure of meiosis (Wang et al, ). However, there was a report indicated that the lack of CK1 increased the duration of meiosis and did not stop meiosis (Qi et al, ).…”