Abstract
The trypsin-like serine protease marapsin is a member of the large protease gene cluster at human chromosome 16p13.3, which also contains the structurally related proteases testisin, tryptase epsilon, tryptase gamma, and EOS. To gain insight into the biological functions of marapsin, we undertook a detailed gene expression analysis. It showed that marapsin expression was restricted to tissues containing stratified squamous epithelia and was absent or only weakly expressed in all other tissues, including the pancreas. Marapsin was constitutively expressed in nonkeratinizing stratified squamous epithelia of human esophagus, tonsil, cervix, larynx, and cornea. In the keratinizing stratified squamous epidermis of skin, however, its expression was induced only during epidermal hyperproliferation, such as in psoriasis and in murine wound healing. In fact, marapsin was the second most strongly up-regulated protease in psoriatic lesions, where expression was localized to the upper region of the hyperplastic epidermis. Similarly, in the hyperproliferative epithelium of regenerating murine skin wounds, marapsin localized to the suprabasal layers, where keratinocytes undergo squamous differentiation. The transient up-regulation of marapsin, which closely correlated with re-epithelialization, was virtually absent in a genetic mouse model of delayed wound closure. These results suggested a function during the process of re-epithelialization. Furthermore, in reconstituted human epidermis, a model system of epidermal differentiation, members of the IL-20 subfamily of cytokines, such as IL-22, induced marapsin expression. Consistent with a physiologic role in marapsin regulation, IL-22 was also strongly expressed in re-epithelializing skin wounds. Marapsin's restricted expression, localization, and cytokine-inducible expression suggest a role in the terminal differentiation of keratinocytes in hyperproliferating squamous epithelia.
Highlights
Gene cluster at human chromosome 16p13.3 and mouse chromosome 17A3.3, respectively [1, 2]
Marapsin Is Expressed in Stratified Squamous Epithelia— Microarray analysis of normal human tissues revealed that marapsin expression was highly specific (Fig. 1)
This study demonstrates that expression of the trypsinlike serine protease marapsin is highly specific and confined to stratified squamous epithelia
Summary
Reagents—Total RNA from human pancreas was purchased from different suppliers The sections were incubated in 10% goat blocking serum, followed by a specific hamster anti-mouse marapsin monoclonal antibody 3B2 at 0.9 g/ml for 60 min. For real time RT-PCR, 50 ng of total RNA was run using the following primers and probes for human marapsin and housekeeping gene RPL19, directed against exon boundaries: marapsin, forward (5Ј-AAGAATGACATGCTGTGCGC-3Ј), reverse (5Ј-CCCGAGTCGCCCTTGC-3Ј), probe (5Ј-(FAM)CTTCGAGGAGGGCAAGAAGGATGCC-(TAMRA)-3Ј); RPL19, forward (5Ј-CAATGCCAACTCCCGTCAG-3Ј), reverse (5Ј-GTCACAGGCTTGCGGATGA-3Ј), probe (5Ј-(FAM)AGATCCGGAAGCTCATCAAAGATGGGCT-(TAMRA)-3Ј). Gene expression data for marapsin of 4138 normal human tissue samples. Results for samples purified from three separate RHE tissues were normalized to the human RPL19 housekeeping gene and expressed as relative -fold change compared with T0 using the comparative Ct method according to the manufacturer’s instructions. RNA samples from 48 h of treatment were used to perform microarray analysis as described [11]
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