Disparate roles forC. elegansDNA translocase paralogs RAD-54.L and RAD-54.B in meiotic prophase germ cells

Abstract

RAD54 family DNA translocases partner with RAD51 recombinases to ensure stable genome inheritance, exhibiting biochemical activities both in promoting recombinase removal and in stabilizing recombinase association with DNA. Understanding how such disparate activities of RAD54 paralogs align with their biological roles is an ongoing challenge. Here we investigate the in vivo functions of C. elegans RAD54 paralogs RAD-54.L and RAD-54.B during meiotic prophase, revealing distinct contributions to the dynamics of RAD-51 association with DNA and to the progression of meiotic double-strand break repair (DSBR). While RAD-54.L is essential for RAD-51 removal from meiotic DSBR sites to enable recombination progression, RAD-54.B is largely dispensable for meiotic DSBR. However, RAD-54.B is required to prevent hyperaccumulation of RAD-51 on unbroken DNA during a key meiotic sub-stage when protein kinase CHK-2 is active. Moreover, DSB-independent hyperaccumulation of RAD-51 foci in the absence of RAD-54.B is RAD-54.L-dependent, revealing a hidden activity of RAD-54.L in promoting promiscuous RAD-51 association that is antagonized by RAD-54.B. We propose a model wherein a division of labor among RAD-54 paralogs allows germ cells to ramp up their capacity for efficient homologous recombination that is crucial to successful meiosis while counteracting potentially deleterious effects of unproductive RAD-51 association with unbroken DNA.

Rad53 regulates the lifetime of Rdh54 at homologous recombination intermediates

“…Our model would implicate Rdh54 as an indirect regulator of overall HR timing with its translocation rate being the property controlled by the kinase signaling pathway. It has recently been discovered that Rad54-B in the C. elegans germline plays a supporting role during meiotic HR (Yamaya et al, 2022). This study also finds that the largest impact in rad54-B animals is when the kinase CHK2 is active, revealing a connection with kinase signaling networks that has also been observed in S. cerevisiae.…”

The translocation activity of Rad54 reduces crossover outcomes during homologous recombination

“…This was inconsistent with our hypothesis but could be explained if Rdh54 had other impacts on the recombination reaction. For example, the deletion of this gene may further inhibit the SDSA pathway (13, 14) or lead to an excess of uncontrolled Rad51 molecules, creating longer Rad51 filaments on ssDNA (41, 72). We did observe a restoration of BIR outcomes to the WT level ( Supplemental Figure 7BCD ), which is consistent with the initial hypothesis.…”

The Synchronized Progression from Mitosis to Meiosis in Female Primordial Germ Cells between Layers and Broilers

“…Genes corresponding to meiosis signaling pathways included structural maintenance of chromosome 3 ( SMC3 ), cyclin-dependent kinase 2 ( CDK2 ), and cell division cycle 20 homolog ( CDC20 ) ( Table 2 ). In addition to the above-mentioned genes, we focused on other genes such as those stimulated by retinoic acid 8 ( STRA8 ) [ 25 ], retinaldehyde dehydrogenase 2 ( RALDH2 ) [ 26 ], and RAD54-like ( RAD54L ) [ 27 ], which played important roles in meiosis initiation and were upregulated in E14 PGCs in both breeds.…”