Peptidylarginine deiminase type I, type II, type III and type IV are expressed in rat epidermis

Peptidylarginine deiminases (PADs) are post-translational modification enzymes to convert protein arginine to citrulline residues in a calcium ion-dependent manner. Here, we investigated the tissue specific expression of PAD type T, II, III and IV by using a reverse transcription-polymerase chain reaction (RT-PCR) method. The type I mRNA was detected only in the epidermis and stomach, and type III mRNA was detected only in the epidermis and ovary. On the other hand, the type II and type IV mRNAs were found in a variety of tissues such as the epidermis, lung, spleen, stomach, kidney, ovary and uterus. The epidermis is the only tissue in which all four PAD mRNAs were detected. The present study suggests strongly that PADs play functionally important roles during the terminal differentiation of epidermal keratinocytes.