cDNA cloning, gene organization and expression analysis of human peptidylarginine deiminase type I

Abstract

Peptidylarginine deiminases (PADs) catalyse a post-translational modification of proteins through the conversion of arginine residues into citrullines. The existence of four isoforms of PAD (types I, II, III and IV) encoded by four different genes, which are distinct in their substrate specificities and tissue-specific expression, was reported in rodents. In the present study, starting from epidermis polyadenylated RNA, we cloned by reverse transcriptase-PCR a full-length cDNA encoding human PAD type I. The cDNA was 2711 bp in length and encoded a 663-amino-acid sequence. The predicted protein shares 75% identity with the rat PAD type I sequence, but displays only 50-57% identity with the three other known human isoforms. We have described the organization of the human PAD type I gene on chromosome 1p36. A recombinant PAD type I was produced in Escherichia coli and shown to be enzymically active. Human PAD type I mRNAs were detected by reverse transcriptase-PCR not only in the epidermis, but also in various organs, including prostate, testis, placenta, spleen and thymus. In human epidermis extracts analysed by Western blotting, PAD type I was detected as a 70 kDa polypeptide, in agreement with its predicted molecular mass. As shown by immunohistochemistry, the enzyme was expressed in all the living layers of human epidermis, with the labelling being increased in the granular layer. This is the first description of the human PAD type I gene and the first demonstration of its expression in epidermis.

Potential protein targets of the peptidylarginine deiminase 2 and peptidylarginine deiminase 4 enzymes in rheumatoid synovial tissue and its possible meaning

“…These enzymes are expressed in most mammalian tissues, with the most common PAD2 enzyme widely distributed throughout human and murine tissues (1). This isoform is responsible for the majority of PAD activity, and the importance of PAD2 has been demonstrated by the observation that all PAD activity is abrogated in the PAD2 knockout mouse (2).…”

Fibrin Deimination in Synovial Tissue Is Not Specific for Rheumatoid Arthritis but Commonly Occurs during Synovitides

“…Protein deimination, mediated by a family of five PAD isoforms (25)(26)(27)(28)(29), is a posttranslational modification described more than 50 years ago (for review, see Ref. 30).…”

Peptidylarginine Deiminases and Protein Deimination in Skin Physiopathology

“…Using RT-PCR experiments we have shown that only three PAD genes are expressed in human skin and epidermis at the mRNA level, namely the PADI1, 2 and 3 genes (Kanno et al, 2000;Ishigami et al, 2002;Guerrin et al, 2003). Messenger RNAs encoding PAD 4 and 6 are not detected in the normal tissue.…”

“…As described in section 2, each PADI gene has its own specific pattern of expression depending on the considered tissue, cell type or differentiation stage of the cells. Among the human PADs, only PAD1, PAD2 and PAD3 are expressed in the skin (Kanno et al, 2000;Ishigami et al, 2002;Guerrin et al, 2003). Here, we will sum up the actual findings on PAD expression in the human epidermis and skin appendages.…”