Chromosome Dynamics Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
J Cell Biol. 2011 Jan 24;192(2):263-76. doi: 10.1083/jcb.201008005. Epub 2011 Jan 17.
Cohesins are multi-subunit protein complexes that regulate sister chromatid cohesion during mitosis and meiosis. Here we identified a novel kleisin subunit of cohesins, RAD21L, which is conserved among vertebrates. In mice, RAD21L is expressed exclusively in early meiosis: it apparently replaces RAD21 in premeiotic S phase, becomes detectable on the axial elements in leptotene, and stays on the axial/lateral elements until mid pachytene. RAD21L then disappears, and is replaced with RAD21. This behavior of RAD21L is unique and distinct from that of REC8, another meiosis-specific kleisin subunit. Remarkably, the disappearance of RAD21L at mid pachytene correlates with the completion of DNA double-strand break repair and the formation of crossovers as judged by colabeling with molecular markers, γ-H2AX, MSH4, and MLH1. RAD21L associates with SMC3, STAG3, and either SMC1α or SMC1β. Our results suggest that cohesin complexes containing RAD21L may be involved in synapsis initiation and crossover recombination between homologous chromosomes.
黏合蛋白是一种多亚基蛋白复合物，可调节有丝分裂和减数分裂过程中姐妹染色单体的黏合。在这里，我们鉴定了一种新型黏合蛋白的 kleisin 亚基 RAD21L，该亚基在脊椎动物中保守存在。在小鼠中，RAD21L 仅在减数分裂早期表达：它显然在减数分裂前期 S 期取代 RAD21，在细线期可检测到轴丝上，并且在粗线期中期之前一直存在于轴丝/侧丝上。然后 RAD21L 消失，并被 RAD21 取代。这种 RAD21L 的行为是独特的，与另一种减数分裂特异性 kleisin 亚基 REC8 不同。值得注意的是，RAD21L 在粗线期中期的消失与 DNA 双链断裂修复的完成以及通过与分子标记γ-H2AX、MSH4 和 MLH1 共标记判断的交叉形成相关。RAD21L 与 SMC3、STAG3 以及 SMC1α 或 SMC1β 相关联。我们的结果表明，含有 RAD21L 的黏合蛋白复合物可能参与同源染色体的联会起始和交叉重组。
