akirin is required for diakinesis bivalent structure and synaptonemal complex disassembly at meiotic prophase I.
During meiosis, evolutionarily conserved mechanisms regulate chromosome remodeling, leading to the formation of a tight bivalent structure. This bivalent, a linked pair of homologous chromosomes, is essential for proper chromosome segregation in meiosis. The formation of a tight bivalent involves chromosome condensation and restructuring around the crossover. The synaptonemal complex (SC), which mediates homologous chromosome association before crossover formation, disassembles concurrently with increased condensation during bivalent remodeling. Both chromosome condensation and SC disassembly are likely critical steps in acquiring functional bivalent structure. The mechanisms controlling SC disassembly, however, remain unclear. Here we identify akir-1 as a gene involved in key events of meiotic prophase I in Caenorhabditis elegans. AKIR-1 is a protein conserved among metazoans that lacks any previously known function in meiosis. We show that akir-1 mutants exhibit severe meiotic defects in late prophase I, including improper disassembly of the SC and aberrant chromosome condensation, independently of the condensin complexes. These late-prophase defects then lead to aberrant reconfiguring of the bivalent. The meiotic divisions are delayed in akir-1 mutants and are accompanied by lagging chromosomes. Our analysis therefore provides evidence for an important role of proper SC disassembly in configuring a functional bivalent structure.
Department of Biology, University of Iowa, Iowa City, IA 52242 , USA.
Amy M
AM
Clemons
Heather M
HM
Brockway
Yizhi
Y
Yin
Bhavatharini
B
Kasinathan
Yaron S
YS
Butterfield
Steven J M
SJ
Jones
Monica P
MP
Colaiácovo
Sarit
S
Smolikove
D000483:Alleles; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D023902:Chromosome Pairing; D002875:Chromosomes / Q000235:genetics / Q000378:metabolism; D003434:Crossing Over, Genetic; D005260:Female; D017404:In Situ Hybridization, Fluorescence; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D049469:Meiotic Prophase I; D008856:Microscopy, Fluorescence; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D034622:RNA Interference; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D013573:Synaptonemal Complex / Q000378:metabolism*; D059008:Time-Lapse Imaging
C583490:Akir-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D008164:Luminescent Proteins; D009687:Nuclear Proteins; C569962:SYP-1 protein, C elegans; C545959:SYP-3 protein, C elegans; D051135:Rad51 Recombinase; C495148:rad-51 protein, C elegans