title: LEKTI fragments specifically inhibit KLK5, KLK7, and KLK14 and control desquamation through a pH-dependent interaction.
abstract: LEKTI is a 15-domain serine proteinase inhibitor whose defective expression underlies the severe autosomal recessive ichthyosiform skin disease, Netherton syndrome. Here, we show that LEKTI is produced as a precursor rapidly cleaved by furin, generating a variety of single or multidomain LEKTI fragments secreted in cultured keratinocytes and in the epidermis. The identity of these biological fragments (D1, D5, D6, D8-D11, and D9-D15) was inferred from biochemical analysis, using a panel of LEKTI antibodies. The functional inhibitory capacity of each fragment was tested on a panel of serine proteases. All LEKTI fragments, except D1, showed specific and differential inhibition of human kallikreins 5, 7, and 14. The strongest inhibition was observed with D8-D11, toward KLK5. Kinetics analysis revealed that this interaction is rapid and irreversible, reflecting an extremely tight binding complex. We demonstrated that pH variations govern this interaction, leading to the release of active KLK5 from the complex at acidic pH. These results identify KLK5, a key actor of the desquamation process, as the major target of LEKTI. They disclose a new mechanism of skin homeostasis by which the epidermal pH gradient allows precisely regulated KLK5 activity and corneodesmosomal cleavage in the most superficial layers of the stratum corneum.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U563, Toulouse, F-31300 France.
authors.forename: Celine
authors.initials: C
authors.lastname: Deraison
authors.forename: Chrystelle
authors.initials: C
authors.lastname: Bonnart
authors.forename: Frederic
authors.initials: F
authors.lastname: Lopez
authors.forename: Celine
authors.initials: C
authors.lastname: Besson
authors.forename: Ross
authors.initials: R
authors.lastname: Robinson
authors.forename: Arumugam
authors.initials: A
authors.lastname: Jayakumar
authors.forename: Fredrik
authors.initials: F
authors.lastname: Wagberg
authors.forename: Maria
authors.initials: M
authors.lastname: Brattsand
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Hachem
authors.forename: Goran
authors.initials: G
authors.lastname: Leonardsson
authors.forename: Alain
authors.initials: A
authors.lastname: Hovnanian
mesh_terms: D000818:Animals; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D000078404:Epidermal Cells; D004817:Epidermis / Q000201:enzymology; D045683:Furin / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007610:Kallikreins / Q000037:antagonists & inhibitors*; D015603:Keratinocytes / Q000378:metabolism; D007641:Keratolytic Agents / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D010446:Peptide Fragments / Q000378:metabolism*; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D053491:Proteinase Inhibitory Proteins, Secretory / Q000737:chemistry / Q000378:metabolism*; D000074163:Serine Peptidase Inhibitor Kazal-Type 5; D015843:Serpins / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D020349:Surface Plasmon Resonance
chemical_list: D007641:Keratolytic Agents; D010446:Peptide Fragments; D011498:Protein Precursors; D053491:Proteinase Inhibitory Proteins, Secretory; C120650:SPINK5 protein, human; D000074163:Serine Peptidase Inhibitor Kazal-Type 5; D015843:Serpins; C495972:Spink5 protein, mouse; D007610:Kallikreins; D045683:Furin