Cystathionine β-synthase gene inactivation dysregulates major urinary protein biogenesis and impairs sexual signaling in mice

Reproductive success in mice depends on major urinary proteins (Mup) that facilitate sexual interactions between females and males. Deletion of cystathionine {beta}-synthase (Cbs) gene, a metabolic gene important for homeostasis of one-carbon metabolism, impairs reproduction by causing female infertility in mice. Here we examined Mup biogenesis and sexual signaling in Cbs-/- vs. Cbs+/- mice. We found that total urinary Mup protein was significantly reduced in male and female Cbs-/- vs. Cbs+/- mice. SDS-PAGE/Western blot, ESIMS, and RT-qPCR analyses of the liver, plasma, and urinary proteins identified a male-specific Mup20 in Cbs-/-, but not Cbs+/- females. As other Mups were significantly reduced, the 18,893 Da Mup20 became the most abundand in urine of Cbs-/- females and males. Effects of Cbs genotype on 18,645 Da, 18,693 Da, and 18,709 Da Mup species abundance were Mup and sex-specific. Cbs-dependent changes in hepatic Mups and Mup20 expression were similar at the protein and mRNA level. Changes in Mups, but not in Mup20, can be explained by downregulation of hepatic Zhx2 and Ghr receptors in Cbs-/- mice. Behavioral testing showed that Cbs+/- females were attracted to Cbs+/- but not to Cbs-/- male urine. Cbs+/- males did not countermark urine of Cbs-/- males but countermarked urine of other Cbs+/- males and were attracted to urines of Cbs-/- as well as Cbs+/- females. Cbs-/- males did not countermark urine of Cbs+/- males but were still attracted to urines of Cbs+/- females. Taken together, these findings show that Cbs, a metabolic gene, plays an important role in the regulation of Mup biogenesis and sexual signaling in mice.