The many faces of the bouquet centrosome MTOC in meiosis and germ cell development

Tools to analyze the organization and formation of the germline cyst in zebrafish oogenesis

“…Importantly, aneuploidy in human eggs is a major cause for miscarriages and infertility, but the mechanistic defects are unknown because we lack a complete understanding of these early stages ( Nagaoka et al, 2012 ; MacLennan et al, 2015 ; Webster and Schuh, 2017 ). A direct connection between cyst morphogenesis and chromosomal pairing regulation was revealed by the identification of the zygotene cilium in zebrafish and mice ( Mytlis et al, 2022 , 2023 ). Thus, characterizing cyst architecture and formation, and deciphering its regulatory mechanisms is essential for understanding meiotic prophase mechanisms.…”

“…1 B, top; see legend for details). A direct connection between the meiosis program and the morphological organization of the cyst was unraveled with our recent identification of the zygotene cilium, an oocyte primary cilium that forms specifically in the germline cyst of zebrafish and mice ( Mytlis et al, 2022 , 2023 ) ( Fig. 1 C).…”

Heterochromatin in plant meiosis

“…In many organisms, the telomeres cluster together to form a bouquet that facilitates homologous interactions in early prophase I of meiosis. Telomere bouquets are required for homologous pairing, synapsis, and recombination [ 165 , 166 ]. Surprisingly, telomere bouquets also play a role in centromere assembly and spindle attachment that promotes proper chromosome segregation in S. pombe [ 167 ], but similar phenotype is not observed in other organisms.…”

“…In many fungi and animals, telomeres cluster on the nuclear envelope (NE) and form a bouquet microtubule organizing center (MTOC) in meiotic prophase I, which is regulated by several telomere-binding proteins, including the Sad1/UNC-84 (SUN) homology and Klarsicht/ANC-1/Syne (KASH) homology (SUN/KASH) complexes [ 166 ]. In S. pombe , a SUN domain protein Sad1 and a putative KASH domain protein Kms1 form a transmembrane complex linking telomeres to microtubules and cytoplasmic dynein for telomere clustering [ 168 ].…”

“…In summary, the LINC complexes, consisting of SUN on inner nuclear membrane and KASH on outer nuclear membrane, play a crucial role in connecting the nucleoplasm and cytoplasm across the NE, thus facilitating the transmission of force from the cytoskeleton to the nuclei. The force is finally transduced onto telomeres via telomere-binding proteins and promotes the movement of telomeres along the NE to transiently cluster in a ‘bouquet’ that brings homologs into close proximity for homologous pairing, synapsis and recombination [ 166 , 172 , 175–178 ].…”