Disrupted development and altered hormone signaling in male Padi2/Padi4 double knockout mice

Peptidylarginine deiminase enzymes (PADs) convert arginine residues to citrulline in a process called citrullination or deimination. Recently, two PADs, PAD2 and PAD4, have been linked to hormone signaling in vitro and the goal of this study was to test for links between PAD2/PAD4 and hormone signaling in vivo. Preliminary analysis of Padi2 and Padi4 single knockout (SKO) mice did not find any overt reproductive defects and we predicted that this was likely due to genetic compensation. To test this hypothesis, we created a Padi2/Padi4 double knockout (DKO) mouse model and tested these mice for a range of reproductive defects. Results from controlled breeding trials found that DKO breeding pairs appeared to take longer to have their first litter than WT controls and that DKO male weanlings weighed significantly less than their WT counterparts. Additionally, DKO males took significantly longer than WT males to reach puberty and also had lower serum testosterone levels. Furthermore, DKO males had smaller testes than WT males and also had increased rates of germ cell apoptosis. The DKO mouse model provides a new tool for investigating PAD function and outcomes from our studies provide the first in vivo evidence linking PADs with hormone signaling. Overall design: The RNAseq study consisted of 3 different genotypes (WT, Padi2 single knockout and Padi2/4 double knockout) each with 2 biological replicates.