PUF-8 facilitates homologous chromosome pairing by promoting proteasome activity during meiotic entry in C. elegans

Abstract

Pairing of homologous chromosomes is essential for genetic recombination during gametogenesis. In many organisms, chromosome ends are attached to cytoplasmic dynein, and dynein-driven chromosomal movements facilitate the pairing process. Factors that promote or control the cytoskeletal tethering of chromosomes are largely unknown. Here, we show that the conserved RNA-binding protein PUF-8 facilitates the tethering and pairing processes in the germline by promoting proteasome activity. We have isolated a hypomorphic allele of, which encodes a proteasome core subunit, and find that the homologous chromosomes fail to pair in the double mutant due to failure of chromosome tethering. Our results reveal that the meiotic defects are caused by the loss of proteasome activity. The axis component HTP-3 accumulates prematurely in the double mutant, and reduction of its activity partially suppresses some of the meiotic defects, suggesting that HTP-3 might be an important target of the proteasome in promoting early meiotic events. In summary, our results reveal a role for the proteasome in chromosome tethering and identify PUF-8 as a regulator of proteasome activity during early meiosis.

The Caenorhabditis elegans proteasome subunit RPN‐12 is required for hermaphrodite germline sex determination and oocyte quality

“…This confirms that the GFP::RPN‐12 is localizing to the proteasome which is both nuclear and cytoplasmically localized. The insets in Figure 3C‐C″′ represent one pachytene region nucleus from the distal region that shows both RPN‐12 and the 20S CP antibody localized adjacent to the chromatin similar to what has been observed with other published fluorescently tagged proteasome subunits 32 …”

“…Proper proteolytic function of the proteasome is important for gametogenesis in C . elegans 32 . To assess the extent by which overall proteolytic activity is affected in the rpn‐12 ( av93 ) mutant, we obtained a recently published strain that provides a readout for proteasome dysfunction 32 .…”

Evolution-guided mutagenesis of the cytoplasmic incompatibility proteins: Identifying CifA’s complex functional repertoire and new essential regions in CifB

“…Catalase-rel domains are predicted to catalyze the degradation of reactive oxygen species (ROS) [ 29 , 30 ]. DUF has a distant homology to globin-like domains and Puf-family RNA-binding domains, which influence the stability of eukaryotic RNAs [ 31 , 32 ]. Finally, STE domains mediate transcriptional induction in yeast [ 33 ].…”

TheC. elegansproteasome subunit RPN-12 is required for hermaphrodite germline sex determination and oocyte quality

“…32 To assess the extent by which overall proteolytic activity is affected in the rpn-12(av93) mutant, we obtained a recently published strain that provides a readout for 9 proteasome dysfunction. 32 This transgenic strain has a non-hydrolysable ubiquitin molecule that is mutated and fused to a GFP tagged Histone H2B and driven by the germline pie-1 promoter (UbG76V::GFP::H2B). The mutation in the ubiquitin causes the GFP and H2B to undergo continuous proteasomal degradation in the germ line.…”