Matriptase and prostasin are expressed in human skin in an inverse trend over the course of differentiation and are targeted to different regions of the plasma membrane

Abstract

Matriptase and prostasin, acting as a tightly coupled proteolytic cascade, were reported to be required for epidermal barrier formation in mouse skin. Here we show that, in human skin, matriptase and prostasin are expressed with an inverse pattern over the course of differentiation. Matriptase was detected primarily in epidermal basal keratinocytes and the basaloid cells in the outer root sheath of hair follicles and the sebaceous gland, where prostasin was not detected. In contrast, prostasin was detected primarily in differentiated cells in the epidermal granular layer, the inner root sheath of hair follicles, and the sebaceous gland, where matriptase expression is negligible. While co-expressed in the middle stage of differentiation, prostasin was detected as polarized patches, and matriptase at intercellular junctions. Targeting to different subcellular localizations is also observed in HaCaT human keratinocytes, in which matriptase was detected primarily at intercellular junctions, and prostasin primarily on membrane protrusion. Furthermore, upon induction of zymogen activation, free active prostasin remains cell-associated and free active matriptase is rapidly shed into the extracellular milieu. Our data suggest that matriptase and prostasin likely function as independent entities in human skin rather than as a tightly coupled proteolytic cascade as observed in mouse skin.

Membrane-Anchored Serine Proteases and Protease-Activated Receptor-2–Mediated Signaling: Co-Conspirators in Cancer Progression

“…In normal tissues, matriptase and prostasin are ubiquitously coexpressed in epithelial cells, whereas during the progression of multi-stage epithelial carcinogenesis, they are found to be expressed in separate tumor cell compartments, possibly indicating altered regulation or activation requirements during tumor progression (108). Results from several studies highlight the importance of tissue distribution and subcellular localization for the function and regulation of these two membrane anchored proteases in other disease contexts (108)(109)(110)(111). It is possible that interactions between their extracellular domains as well as tightly regulated membrane distribution and subcellular localization all contribute to regulating the activation of the matriptase-PAR-2 axis as well.…”

Tissue distribution and subcellular localizations determine in vivo functional relationship among prostasin, matriptase, HAI-1, and HAI-2 in human skin

“…Matriptase expression is negligible in the granular layer of the human skin. A similar matriptase expression profile has been observed during the course of differentiation in the hair follicle and sebaceous gland, both of which are histologically connected with and resemble the epidermis regarding life-long renewal through proliferation and progressive programmed differentiation [ 18 , 21 ]. The downregulation of matriptase expression associated with increased differentiation is in stark contrast to the differentiation-associated upregulation of prostasin expression that is seen in human epidermis, where prostasin is primarily detected in the keratinocytes of the granular layer with some expression in the upper spinous layers [ 6 ].…”

“…The skin tissue sections were obtained from patients, with written informed consent by the Tri-Service General Hospital (TSGH), National Defense Medical Center under IRB protocol 099-05-019, approved by the TSGH Institutional Review Board (IRB). Immunohistochemical staining was conducted as described in previous studies [ 18 , 19 , 29 ]. Sections of frozen human skin were fixed with formalin and stained using the matriptase mAb M24, the activated matriptase mAb M69, the prostasin mAb YL11, the activated prostasin mAb YL89, the HAI-1 mAb M19, the HAI-2 mAb DC16 or mouse IgG as negative control and followed by the secondary antibody (EnVision+ Dual Link System Peroxidase) (Dako, Glostrup, Denmark).…”

“…In spite of this well-defined functional relationship, the inverse matriptase and prostasin expression pattern that can be observed through the course of epidermal differentiation [ 18 ] suggests that the functional link between the two serine proteases may not be as strong in human skin as has been observed in mouse and cultured human cells. In quiescent human skin, matriptase is primarily expressed by the basal and spinous keratinocytes [ 7 , 18 , 19 ] suggesting a possible role in keratinocyte proliferation and early differentiation [ 20 ]. Matriptase expression is negligible in the granular layer of the human skin.…”

Natural Endogenous Human Matriptase and Prostasin Undergo Zymogen Activation via Independent Mechanisms in an Uncoupled Manner

“…In human epidermis matriptase is expressed by the basal and spinous keratinocytes, whereas the granular keratinocytes express matriptase at negligible levels [38,39]. In contrast, prostasin is expressed primarily by the granular keratinocytes and not detected in the basal keratinocytes [40]. Nevertheless, matriptase and prostasin are co-expressed in several human epithelial cells in which induction of robust matriptase autoactivation does result in prostasin zymogen activation.…”