Peptidylarginine Deiminase Isoforms 1–3 Are Expressed in the Epidermis and Involved in the Deimination of K1 and Filaggrin

Abstract

Post-translational conversion of arginine to citrulline residues is catalyzed by peptidylarginine deiminases (PAD). Although the existence of five isoforms of PAD has been reported in rodents and humans, their tissue distribution, substrate specificity, and physiological function have yet to be explored. In the epidermis, deimination of filaggrin and keratins is involved in maintaining hydration of the stratum corneum (SC), and hence the cutaneous barrier function. Here, RT-PCR, western blotting, and confocal microscopy analyses with anti-peptide antibodies highly specific for each of the PAD1-4 demonstrated that only PAD1-3 are expressed in mouse and human epidermis. PAD1 was detected in all layers, including the SC, and PAD2 in all the living layers, whereas PAD3 expression was shown to be restricted to the granular layer and lower SC. Moreover, PAD1 and 3 were observed to co-localize with (pro)filaggrin, and PAD2 to be located at the keratinocyte periphery in the stratum granulosum. We also detected PAD1 in extracts of superficial SC, where K1 is deiminated. Moreover, we showed that PAD1 and 3 are able to modify filaggrin in vitro. These data strongly suggest that each enzyme exerts a specific role in the course of epidermis differentiation.

Specific Citrullination Causes Assembly of a Globular S100A3 Homotetramer

“…The granules with PAD1 immunoreactivity were clearly discriminated from the nuclear and cytoplasmic distribution of S100A3. PAD1 in the differentiating cortical cells appeared to be associated with hair keratin fiber, as has been described for the epidermis (18,38). PAD2 was observed as granular patches from the early differentiation stages of all hair epithelial matrix daughter cells; however, as each cellular differentiation advanced, PAD2 appeared in the cytoplasm and partially colocalized with S100A3 in the cuticular and cortical cells.…”

“…PAD Isozymes Modified S100A3 in Hair Follicle-In the mammalian cutaneous epithelium, protein-citrullination is reported to be catalyzed by PAD1, PAD2, and PAD3 (38) among the five known isozymes (39). In hair follicles, PAD3 is located in the cuticular cells expressing S100A3 (24 -26) as well as in the inner root sheaths and the medulla, where it co-localizes with trichohyalin (35,40).…”

Peptidylarginine deiminase and protein citrullination in prion diseases

“…PAD1 is expressed in the epidermis, uterus and hair follicles. 10,11 It is detected in the entire epidermis with an increasing gradient from the basal layer to the granular layer. Keratins K1 and K10 are known substrates of PAD1 during keratinocyte terminal differentiation.…”

Peptidylarginine Deiminases and Protein Deimination in Skin Physiopathology

“…Recently, vertebrate PADs were categorized into five isotypes, named PAD type I (PAD1), type II (PAD2), type III (PAD3), type IV (PAD4), and type VI (PAD6), based on their amino acid sequences, substrate specificities and tissue location (Chavanas et al, 2004;Nachat et al, 2005aNachat et al, , 2005b. PAD4 has been previously designated as PAD5 (Vossenaar et al, 2003).…”