LEKTI fragments specifically inhibit KLK5, KLK7, and KLK14 and control desquamation through a pH-dependent interaction.
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.
Deraison
Celine
C
Institut National de la Santé et de la Recherche Médicale, U563, Toulouse, F-31300 France.
Bonnart
Chrystelle
C
Lopez
Frederic
F
Besson
Celine
C
Robinson
Ross
R
Jayakumar
Arumugam
A
Wagberg
Fredrik
F
Brattsand
Maria
M
Hachem
Jean Pierre
JP
Leonardsson
Goran
G
Hovnanian
Alain
A
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
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