Specific Citrullination Causes Assembly of a Globular S100A3 Homotetramer

Abstract

S100A3 is a unique member of the Ca 2؉ -binding S100 protein family with the highest cysteine content and affinity for Zn 2؉ . This protein is highly expressed in the differentiating cuticular cells within the hair follicle and organized into mature hair cuticles. Previous studies suggest a close association of S100A3 with epithelial differentiation, leading to hair shaft formation, but its molecular function is still unknown. By two-dimensional PAGE-Western blot analyses using a modified citrulline antibody, we discovered that more than half of the arginine residues of native S100A3 are progressively converted to citrullines by Ca 2؉ -dependent peptidylarginine deiminases. Confocal immunofluorescent microscopy showed that the cytoplasmic S100A3 within the cuticular layer is mostly co-localized with the type III isoform of peptidylarginine deiminase (PAD3) but not with PAD1. Recombinant PAD1 and PAD2 are capable of converting all 4 arginines in recombinant S100A3, whereas PAD3 specifically converts only Arg-51 into citrulline. Gel filtration analyses showed that either enzymatic conversion of Arg-51 in S100A3 to citrulline or its mutational substitution with alanine (R51A) promotes a homotetramer assembly. Fluorescent titration of R51A suggested that its potential Ca 2؉ binding property increased during tetramerization. A prototype structural model of the globular Ca 2؉ -bound S100A3 tetramer with citrulline residues is presented. High concentrations of S100A3 homotetramer might provide the millimolar level of Ca 2؉ required for hair cuticular barrier formation.

Blockade of S100A3 activity inhibits murine hair growth

“…S100A3 is overexpressed in head and neck cancer, colorectal cancer, bladder cancer, gastric cancer, and astrocytic tumors, but has an inverse correlation to breast cancer progression (Lloyd et al, 1996;Camby et al, 2000;Yao et al, 2007;Liu et al, 2008Liu et al, , 2013Tyszkiewicz et al, 2014). It is also highly expressed in hair root cells, and is thought to have a role in epithelial cell differentiation and Ca 2+ -dependent hair cuticular barrier formation (Kizawa et al, 2008). The present study demonstrated that subcutaneous injection with anti-S100A3 antibody led to hair growth retardation and a reduced number of hair follicles (Figures 3-5).…”

Peptidylarginine Deiminases and Protein Deimination in Skin Physiopathology

“…The deimination of trichohyalin catalyzed by PAD3 is crucial for the properties of trichohyalin, as well as for S100A3, another major protein of the hair follicles (Tarcsa et al, 1996(Tarcsa et al, , 1997Steinert et al, 2003;Kizawa et al, 2008). Thereby, PAD3 is likely to play a major role in the establishment of the mechanical resistance of cells in the hair follicles and particularly in the hair shaft.…”

“…PAD2 is thought to play a role in the onset and progression of neurodegenerative human disorders, including Alzheimer disease and multiple sclerosis, and it has also been implicated in glaucoma pathogenesis (Bhattacharya et al, 2006;Moscarello et al, 2007;Cafaro et al, 2010). Human PAD3 modulates hair follicle structural proteins, such as trichohyalin and S100A3 in the inner root sheath (Rogers et al, 1997;Kanno et al, 2000;Kizawa et al, 2008). Together with the PAD1 enzyme, PAD3 may also play a role in terminal differentiation of the epidermis (Senshu et al, 1996;Méchin et al, 2007).…”

“…PAD3 is also colocalized with S100A3, a calcium-binding protein of the S100 protein family supposed to be involved in hair cell differentiation. In vitro deimination by PAD3 of S100A3 at the Arg-51 promotes the assembly of a homotetramer, and increases its affinity for calcium ions (Kizawa et al, 2008).…”

Arachidonate 12-Lipoxygenase Inhibitors Promote S100A3 Citrullination in Cultured SW480 Cells and Isolated Hair Follicles

“…4) Peptidylarginine deiminase (PADI) converts several arginine residues of S100A3 protein to citrullines within immature cuticular cells. 5) Genetic mutations including hair-dominant PADI isotype (PADI3) have recently been shown to cause uncombable hair syndrome.…”