High impact information on Smc1b

• To elucidate the role of the meiosis-specific cohesin SMC1beta (encoded by Smc1l2) in oogenesis, we carried out meiotic studies of female SMC1beta-deficient mice [1].
• Our results provide the first direct evidence that SMC1beta acts as a chiasma binder in mammals, stabilizing sites of exchange until anaphase [1].
• Cohesin SMC1 beta is required for meiotic chromosome dynamics, sister chromatid cohesion and DNA recombination [2].
• Thus, SMC1 beta has a key role in meiotic cohesion, the assembly of AEs, synapsis, recombination, and chromosome movements [2].
• Using cDNA microarray experiments comparing wild-type and E2f6-/- mouse embryonic fibroblasts, we now found that E2F6 is required to silence the meiosis-specific genes SMC1beta and STAG3 in somatic cells [3].

Biological context of Smc1b

• Meiosis-specific components of the cohesin complex, including the recently described SMC1 isoform SMC1 beta, were suggested to be required for meiotic sister chromatid cohesion and DNA recombination [2].
• Transcriptional repression of SMC1beta and STAG3 by E2F6 involves multiple mechanisms, including methylation of histone H3 on lysine 9 and lysine 27 [3].
• SMC1beta was localized along the chromosomal arms as well as on the centromeres in meiotic prophase I, and its existence on the chromosomes persisted up to metaphase II, a situation different from that reported in the mouse, in which SMC1beta is lost from the chromosome arms in late pachytene despite its universal presence in vertebrates [4].

Anatomical context of Smc1b

• SMC1beta was expressed in spermatogonia and spermatocytes [4].

Other interactions of Smc1b

• Actually, several meiosis-specific cohesin subunits, including Rec8, STAG3 and SMC1beta, are known to exist in mammals; however, there are no reports of meiosis-specific cohesin subunits in other vertebrates [4].

References