title: Deimination of Human Hornerin Enhances its Processing by Calpain-1 and its Cross-Linking by Transglutaminases.
abstract: Hornerin (HRNR) shares numerous features with filaggrin, a key contributor to the epidermal barrier functions. The two proteins display a related structural organization, are expressed by the granular keratinocytes as a large precursor processed by proteolysis, and are cross-linked to the cornified cell envelopes. Two main steps in the metabolism of filaggrin are its deimination and calpain-1 cleavage. Here, using ion-exchange chromatography and two-dimensional gel electrophoresis of human epidermis extracts, we determined that HRNR is deiminated in vivo. Accordingly, cornified envelopes, purified from plantar and abdominal human skin, were shown to contain deiminated proteins. A recombinant form of HRNR (HRNRHis) deiminated in vitro was shown to be a better substrate for transglutaminases 1 and 3 than the unmodified form. Our data also indicated that calpain-1 may be involved in the proteolytic processing of HRNR, because calpain-1 was co-located with HRNR in the cytoplasm of granular keratinocytes. Using Western blotting and mass spectrometry analysis, HRNRHiswas shown to be cleaved by calpain-1 in vitro, its deimination enhancing its proteolysis. In HRNR full sequence, four calpain-1 cleavage sites were identified. Altogether, these data allowed a new role to be deciphered for deimination during cornification and provided further characterization of HRNR metabolism.
authors.affiliation: Unité Différenciation Epithéliale et Autoimmunité Rhumatoïde, Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse Midi-Pyrénées, Université Toulouse III, Toulouse, France.
authors.forename: Chiung-Yueh
authors.initials: CY
authors.lastname: Hsu
authors.affiliation: Unité Différenciation Epithéliale et Autoimmunité Rhumatoïde, Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse Midi-Pyrénées, Université Toulouse III, Toulouse, France.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Gasc
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse Midi-Pyrénées, CNRS, Université Toulouse III, Toulouse, France.
authors.forename: Anne-Aurélie
authors.initials: AA
authors.lastname: Raymond
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse Midi-Pyrénées, CNRS, Université Toulouse III, Toulouse, France.
authors.forename: Odile
authors.initials: O
authors.lastname: Burlet-Schiltz
authors.affiliation: School of Agriculture, University of Ibaraki, Ibaraki, Japan.
authors.forename: Hidenari
authors.initials: H
authors.lastname: Takahara
authors.affiliation: Unité Différenciation Epithéliale et Autoimmunité Rhumatoïde, Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse Midi-Pyrénées, Université Toulouse III, Toulouse, France.
authors.forename: Guy
authors.initials: G
authors.lastname: Serre
authors.affiliation: Unité Différenciation Epithéliale et Autoimmunité Rhumatoïde, Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse Midi-Pyrénées, Université Toulouse III, Toulouse, France.
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Méchin
authors.affiliation: Unité Différenciation Epithéliale et Autoimmunité Rhumatoïde, Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse Midi-Pyrénées, Université Toulouse III, Toulouse, France. Electronic address: michel.simon@inserm.fr.
authors.forename: Michel
authors.initials: M
authors.lastname: Simon
mesh_terms: D002135:Calcium-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D002154:Calpain / Q000032:analysis / Q000502:physiology*; D053456:Caspase 14 / Q000502:physiology; D004817:Epidermis / Q000737:chemistry; D000091344:Filaggrin Proteins; D006801:Humans; D007381:Intermediate Filament Proteins / Q000032:analysis / Q000378:metabolism*; D011503:Transglutaminases / Q000502:physiology*
chemical_list: D002135:Calcium-Binding Proteins; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; C503908:HRNR protein, human; D007381:Intermediate Filament Proteins; D011503:Transglutaminases; D002154:Calpain; D053456:Caspase 14; C484806:CAPN1 protein, human