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

Abstract

The successful delivery of genetic material to gametes requires tightly regulated interactions between the parental chromosomes. Central to this regulation is a conserved chromosomal interface called the synaptonemal complex (SC), which brings the parental chromosomes in close proximity along their length. While many of its components are known, the interfaces that mediate the assembly of the SC remain a mystery. Here, we survey findings from different model systems while focusing on insight gained in the nematode C. elegans. We synthesize our current understanding of the structure, dynamics, and biophysical properties of the SC and propose mechanisms for SC assembly.

Chemically induced proximity reveals mechanotransduction of a meiotic checkpoint at the nuclear envelope

“…Representative immunofluorescence images showing phenotypes in meiotic nuclei from animals homozygous for plk-2(K65M)::3xFLAG::TIR1CIP . The absence of polarized nuclear morphology and defects in chromosome pairing and synapsis recapitulate phenotypes previously described in worms homozygous for untagged plk-2(K65M) (4; 5) or a similar plk-2(P197L) mutant defective in kinase activity (6). Scale bars, 10 µm.…”

Ultraviolet attenuates centromere-mediated meiotic genome stability and alters gametophytic ploidy consistency in flowering plants

“…Defects in DSB repair result in failed crossovers (COs) between homologs and production of univalents, and/or chromosome fragmentation (Sanchez-Moran et al, 2007; Su et al, 2017). During meiotic recombination, homologous chromosomes undergo pairing and synapsis, which involves assembly of the synaptonemal complex (SC) between the juxtaposed homologs (Gordon and Rog, 2023). The lateral and central elements of SC are composed of the HORMA domain protein HOP1/ASY1 and the transverse filament protein ZYP1, respectively (Armstrong et al, 2002; Higgins et al, 2005).…”

Uncharted territories: Solving the mysteries of male meiosis in flies

“…Here, we distinguish between homolog alignment, which we define as the 2 homologous copies coming into close physical proximity in the nucleus and aligning from end-to-end, and pairing, which occurs after alignment and involves intimate inter-chromosomal associations that may or may not be dependent on the formation of the synaptonemal complex (SC). In conventional meiosis, the SC forms in a structurally conserved tripartite manner, with lateral elements along each homolog connected to central elements by transverse filaments (reviewed in [1,2]). These pairing interactions are stabilized by crossovers (COs) that form during genetic recombination, creating physical links between the homologs that remain even after dissociation of the SC known as chiasma (singular) or chiasmata (plural).…”