Dynamics of cohesin proteins REC8, STAG3, SMC1β and SMC3 are consistent with a role in sister chromatid cohesion during meiosis in human oocytes
Authors: Garcia-Cruz, R.; Brieo, M.A.; Roig, I.; Grossmann, M.; Velilla, E.; Pujol, A.; Cabero, L.; Pessarrodona, A.; Barbero, J.L.; Garcia Calds, M.
Source: Human Reproduction, Volume 25, Number 9, 20 September 2010 , pp. 2316-2327(12)
Publisher: Oxford University Press
Abstract:BACKGROUNDSister chromatid cohesion is essential for ordered chromosome segregation at mitosis and meiosis. This is carried out by cohesin complexes, comprising four proteins, which seem to form a ring-like complex. Data from animal models suggest that loss of sister chromatid cohesion may be involved in age-related non-disjunction in human oocytes. Here, we describe the distribution of cohesins throughout meiosis in human oocytes.METHODSWe used immunofluorescence in human oocytes at different meiotic stages to detect cohesin subunits REC8, STAG3, SMC1 and SMC3, [also synaptonemal complex (SC) protein 3 and shugoshin 1]. Samples from euploid fetuses and adult women were collected, and 51 metaphase I (MI) and 113 metaphase II (MII) oocytes analyzed. SMC1 transcript levels were quantified in 85 maturing germinal vesicle (GV) oocytes from 34 women aged 1943 years by real-time PCR.RESULTSAt prophase I, cohesin subunits REC8, STAG3, SMC1 and SMC3 overlapped with the lateral element of the SC. Short cohesin fibers are observed in the oocyte nucleus during dictyate arrest. All four subunits are observed at centromeres and along chromosomal arms, except at chiasmata, at MI and are present at centromeric domains from anaphase I to MII. SMC1 transcripts were detected (with high inter-sample variability) in GV oocytes but no correlation between SMC1 mRNA levels and age was found.CONCLUSIONSThe dynamics of cohesins REC8, STAG3, SMC1 and SMC3 suggest their participation in sister chromatid cohesion throughout the whole meiotic process in human oocytes. Our data do not support the view that decreased levels of SMC1 gene expression in older women are involved in age-related non-disjunction.
Document Type: Research article
Publication date: 2010-09-20
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