Loss, Gain, and Retention: Mechanisms Driving Late Prophase I Chromosome Remodeling for Accurate Meiotic Chromosome Segregation

Abstract

To generate gametes, sexually reproducing organisms need to achieve a reduction in ploidy, via meiosis. Several mechanisms are set in place to ensure proper reductional chromosome segregation at the first meiotic division (MI), including chromosome remodeling during late prophase I. Chromosome remodeling after crossover formation involves changes in chromosome condensation and restructuring, resulting in a compact bivalent, with sister kinetochores oriented to opposite poles, whose structure is crucial for localized loss of cohesion and accurate chromosome segregation. Here, we review the general processes involved in late prophase I chromosome remodeling, their regulation, and the strategies devised by different organisms to produce bivalents with configurations that promote accurate segregation.

Building the synaptonemal complex: Molecular interactions between the axis and the central region

“…Later, the CR is depleted from the rest of the chromosome. Concomitant with CR partitioning to the short arm, HTP-1/2 are partitioned to the long arm, while HIM-3 and HTP-3 remain on both arms [ 110 , 111 ]. The seeming repulsion of the CR away from HTP-1/2 and towards an arm that only contains HIM-3 and HTP-3 could indicate that the CR has a higher affinity for HIM-3 and HTP-3 and a weaker affinity for HTP-1/2.…”

Kinase PLK1 regulates the disassembly of the lateral elements and the assembly of the inner centromere during the diakinesis/metaphase I transition in male mouse meiosis

“…In previous reports a concise description of the distribution of SYCP3 and HORMAD1 in diakinesis and metaphase I spermatocytes was presented ( Parra et al, 2004 ; Parra et al, 2006 ; Wojtasz et al, 2009 ). In this sense, SYCP3 disassembles from the LEs during late prophase I stages and then accumulate at the centromeres in metaphase I spermatocytes ( Cahoon and Hawley, 2016 ; Gao and Colaiácovo, 2018 ; Láscarez-Lagunas et al, 2022 ). However, a precise description of this dynamic hasn’t been reported.…”

“…Studies on mouse spermatocytes indicated a gradual disassembly of the LE protein SYCP3 during late prophase I stages, and its accumulation at metaphase I inner centromeres ( Dobson et al, 1994 ; Prieto et al, 2001 ; Eijpe et al, 2003 ; Parra et al, 2004 ; Gómez et al, 2007 ). However, the precise sequence of events leading to these processes, and their regulation, are poorly understood in vertebrates ( Cahoon and Hawley, 2016 ; Gao and Colaiácovo, 2018 ; Láscarez-Lagunas et al, 2022 ).…”