A new role for the mitotic RAD21/SCC1 cohesin in meiotic chromosome cohesion and segregation in the mouse.

The evolutionarily conserved cohesin complex is required for the establishment and maintenance of sister chromatid cohesion, in turn essential for proper chromosome segregation. RAD21/SCC1 is a regulatory subunit of the mitotic cohesin complex, as it links together all other subunits of the complex. The destruction of RAD21/SCC1 along chromosomal arms and later at centromeres results in the dissociation of the cohesin complex, facilitating chromosome segregation. Here, we report for the first time that mammalian RAD21/SCC1 associates with the axial/lateral elements of the synaptonemal complex along chromosome arms and on centromeres of mouse spermatocytes. Importantly, RAD21/SCC1 is lost from chromosome arms in late prophase I but persists on centromeres. The loss of centromeric RAD21/SCC1 coincides with the separation of sister chromatids at anaphase II. These findings support a role for mammalian RAD21/SCC1 in maintaining sister chromatid cohesion in meiosis.