Detection of condensin I and II in maturing pig oocytes

Abstract

The multiprotein complexes known as condensins (I and II) are major players in chromosome dynamics in mitotic and meiotic cells. Here, we report for the first time the detection of different condensin subunits from both complexes in mammalian oocytes. Using immunoblotting analysis we examined expression levels of condensin subunits during meiotic maturation of porcine oocytes. The expression of the core subunit structural maintenance of chromosomes 2 (SMC2), identical in both condensin complexes, did not change significantly during maturation. Similarly, there was no significant change in the expression of the chromosome associated protein (CAP)-H and CAP-H2 subunits, components of condensin I and II, respectively. Conversely, the expression profiles of CAP-G, CAP-D2 (condensin I) and CAP-D3 (condensin II) were more interesting. At least two isoforms of the CAP-D2 subunit were detected, along with three isoforms of the CAP-D3 and CAP-G subunits. We suggest that this diverse migration of subunit isoforms is due to post-translational modification. Earlier, it was reported that non-SMC proteins are phosphorylated by cyclin-dependent kinase 1. In the present study, we analysed the phosphorylation status of the three subunits in oocyte extracts using alkaline phosphatase treatment and we found that at least the fastest migrating form of CAP-D3 was likely to be phosphorylated in maturing porcine oocytes. In addition, the localisation of CAP-H and CAP-H2 subunits was examined using immunofluorescence staining with specific antibodies, as well as following microinjection of their enhanced green fluorescent protein-tagged mRNA into germinal vesicle-stage oocytes. CAP-H was found in the cytoplasm, whereas CAP-H2 was localised within the nucleus.

Condensins I and II are essential for construction of bivalent chromosomes in mouse oocytes

“…Although emerging studies in invertebrate model organisms have begun to uncover essential functions of condensins in meiotic chromosome structure and function, only fragmentary and limited information is available from studies in vertebrates such as Xenopus laevis (Watrin et al , 2003), pig (Liskova et al , 2010), and mouse (Viera et al , 2007). The present report is the first comprehensive study to investigate the expression, chromosomal localization, and potential functions of the two condensin complexes in mouse oocytes.…”

Aurora Kinase A Is Not Involved in CPEB1 Phosphorylation and cyclin B1 mRNA Polyadenylation during Meiotic Maturation of Porcine Oocytes

“…Porcine oocytes were microinjected as was described previously [28]. Briefly, isolated oocytes were denuded and kept in supplemented M199 medium without hormones for 1 h at 38.5 °C.…”

Condensins: universal organizers of chromosomes with diverse functions

“…An early study using mouse spermatocytes reported that a condensin I subunit (CAP-H) is concentrated on a fuzzy axial structure within chromatids in both meiosis I and meiosis II (Viera et al 2007). Whereas the existence of condensins I and II was initially reported in pig oocytes (Lisková et al 2010), a more recent study in mouse oocytes has described a comprehensive picture of the dynamics and function of condensins I and II (Lee et al 2011). At prophase of meiosis I (prophase I), condensin I is present in the cytoplasm, whereas condensin II is localized within the nucleus.…”