Membrane-anchored serine protease matriptase regulates epithelial barrier formation and permeability in the intestine.
The intestinal epithelium serves as a major protective barrier between the mammalian host and the external environment. Here we show that the transmembrane serine protease matriptase plays a pivotol role in the formation and integrity of the intestinal epithelial barrier. St14 hypomorphic mice, which have a 100-fold reduction in intestinal matriptase mRNA levels, display a 35% reduction in intestinal transepithelial electrical resistance (TEER). Matriptase is expressed during intestinal epithelial differentiation and colocalizes with E-cadherin to apical junctional complexes (AJC) in differentiated polarized Caco-2 monolayers. Inhibition of matriptase activity using a specific peptide inhibitor or by knockdown of matriptase by siRNA disrupts the development of TEER in barrier-forming Caco-2 monolayers and increases paracellular permeability to macromolecular FITC-dextran. Loss of matriptase was associated with enhanced expression and incorporation of the permeability-associated, "leaky" tight junction protein claudin-2 at intercellular junctions. Knockdown of claudin-2 enhanced the development of TEER in matriptase-silenced Caco-2 monolayers, suggesting that the reduced barrier integrity was caused, at least in part, by an inability to regulate claudin-2 expression and incorporation into junctions. We find that matriptase enhances the rate of claudin-2 protein turnover, and that this is mediated indirectly through an atypical PKCzeta-dependent signaling pathway. These results support a key role for matriptase in regulating intestinal epithelial barrier competence, and suggest an intriguing link between pericellular serine protease activity and tight junction assembly in polarized epithelia.
Department of Physiology, Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Marguerite S
MS
Buzza
Sarah
S
Netzel-Arnett
Terez
T
Shea-Donohue
Aiping
A
Zhao
Chen-Yong
CY
Lin
Karin
K
List
Roman
R
Szabo
Alessio
A
Fasano
Thomas H
TH
Bugge
Toni M
TM
Antalis
D018938:Caco-2 Cells; D002462:Cell Membrane / Q000201:enzymology; D049109:Cell Proliferation; D057167:Claudins; D020868:Gene Silencing; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D010539:Permeability; D011493:Protein Kinase C / Q000378:metabolism; D034741:RNA, Small Interfering; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D000099221:Protein Kinase C zeta
D057167:Claudins; D008565:Membrane Proteins; D011493:Protein Kinase C; D034741:RNA, Small Interfering; D012697:Serine Endopeptidases; D000099221:Protein Kinase C zeta; C491875:CLDN2 protein, human; C485595:matriptase