Compensation for X-linked Pdha1 silencing by Pdha2 is essential for meiotic double-strand break repair in spermatogenesis.

It is known that various testis-specific mitochondrial proteins are associated with energy metabolism and male meiosis. PDHA2 is a testis-specific mitochondrial protein, and its encoding gene is speculated to be an autosomal retrogene of the progenitor X-linked Pdha1. Here, we show that Pdha2 knockout (KO) mice exhibit azoospermia due to failure at the late pachytene-diplotene transition. We found that PDHA2 interacts with PDHB and PDHA1. PDHA2 absence leads to decreased PDHB amounts and ATP levels in male germ cells. ATP reduction impairs the function of the ATPase recombination proteins RAD51 and DMC1, causing crossover formation deficiency, further resulting in double-strand break repair failure at the pachytene stage. Pdha1 expression by transgenes in Pdha2 KO germ cells rescues fertility and PDHB expression in Pdha2 KO males, confirming the functional equivalence of PDHA1 and PDHA2. Because X-linked Pdha1 expression is silenced during meiotic sex chromosome inactivation, our findings also support the hypothesis that Pdha2 was transposed from Pdha1. In summary, PDHA2 compensates for silenced PDHA1 in male germ cells, and plays a crucial role in maintaining efficient double-strand break repair for proper meiotic progression.