Regulation of the matriptase-prostasin cell surface proteolytic cascade by hepatocyte growth factor activator inhibitor-1 during epidermal differentiation.
Matriptase, a membrane-tethered serine protease, plays essential roles in epidermal differentiation and barrier function, largely mediated via its activation of prostasin, a glycosylphosphatidylinositol-anchored serine protease. Matriptase activity is tightly regulated by its inhibitor hepatocyte growth factor activator inhibitor-1 (HAI-1) such that free active matriptase is only briefly available to act on its substrates. In the current study we provide evidence for how matriptase activates prostasin under this tight control by HAI-1. When primary human keratinocytes are induced to differentiate in a skin organotypic culture model, both matriptase and prostasin are constitutively activated and then inhibited by HAI-1. These processes also occur in HaCaT human keratinocytes when matriptase activation is induced by exposure of the cells to a pH 6.0 buffer. Using this acid-inducible activation system we demonstrate that prostatin activation is suppressed by matriptase knockdown and by blocking matriptase activation with sodium chloride, suggesting that prostatin activation is dependent on matriptase in this system. Kinetics studies further reveal that the timing of autoactivation of matriptase, prostasin activation, and inhibition of both enzymes by HAI-1 binding are closely correlated. These data suggest that, during epidermal differentiation, the matriptase-prostasin proteolytic cascade is tightly regulated by two mechanisms: 1) prostasin activation temporally coupled to matriptase autoactivation and 2) HAI-1 rapidly inhibiting not only active matriptase but also active prostasin, resulting in an extremely brief window of opportunity for both active matriptase and active prostasin to act on their substrates.
Chen
Ya-Wen
YW
Greenebaum Cancer Center, University of Maryland, Baltimore, Maryland 21201, USA.
Wang
Jehng-Kang
JK
Chou
Feng-Pai
FP
Chen
Chiu-Yuan
CY
Rorke
Ellen A
EA
Chen
Li-Mei
LM
Chai
Karl X
KX
Eckert
Richard L
RL
Johnson
Michael D
MD
Lin
Chen-Yong
CY
D016475:3T3 Cells; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D004817:Epidermis / Q000201:enzymology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015603:Keratinocytes / Q000201:enzymology*; D051379:Mice; D053491:Proteinase Inhibitory Proteins, Secretory / Q000378:metabolism* / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism*; D000099271:Prostasin
D053491:Proteinase Inhibitory Proteins, Secretory; D012697:Serine Endopeptidases; D000099271:Prostasin; C109149:SPINT1 protein, human; C485596:ST14 protein, human