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Identification and cloning of the membrane-associated serine protease, hepsin, from mouse preimplantation embryos
1Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA.
Abstract:
Previous studies have suggested the existence of a membrane-associated serine protease expressed by mammalian preimplantation embryos. In this study, we have identified hepsin, a type II transmembrane serine protease, in early mouse blastocysts. Mouse hepsin was highly homologous to the previously identified human and rat cDNAs. Two isoforms, differing in their cytoplasmic domains, were detected. The tissue distribution of mouse hepsin was similar to that seen in humans, with prominent expression in liver and kidney. In mouse embryos, hepsin expression was observed in the two-cell stage, reached a maximal level at the early blastocyst stage, and decreased subsequent to blastocyst hatching. Expression of a soluble form of hepsin revealed its ability to autoactivate in a concentration-dependent manner. Catalytically inactive soluble hepsin was unable to autoactivate. These results suggest that hepsin may be the first serine protease expressed during mammalian development, making its ability to autoactivate critical to its function.
Insights
Mammalian preimplantation embryos express hepsin, a serine protease. This protease autoactivates, suggesting its critical role in early mammalian development.
Area of Science:
- Biochemistry
- Developmental Biology
- Molecular Biology
Background:
- Mammalian preimplantation embryos are known to express membrane-associated serine proteases.
- The specific identity and function of these proteases during early development have remained largely uncharacterized.
Purpose of the Study:
- To identify and characterize a specific serine protease in early mouse embryos.
- To investigate the expression pattern and functional properties of this protease during mammalian preimplantation development.
Main Methods:
- Identification of hepsin in mouse blastocysts using molecular cloning techniques.
- Analysis of hepsin cDNA homology with human and rat sequences.
- Detection of hepsin isoforms via Western blotting.
- Tissue distribution analysis of mouse hepsin.
- Quantitative analysis of hepsin expression in mouse embryos at different developmental stages.
- In vitro studies on the autoactivation of soluble hepsin and its catalytically inactive mutant.
Main Results:
- Hepsin, a type II transmembrane serine protease, was identified in early mouse blastocysts.
- Mouse hepsin exhibited high homology to human and rat counterparts, with two isoforms detected.
- Hepsin expression was prominent in adult mouse liver and kidney, mirroring human tissue distribution.
- In embryos, hepsin expression began at the two-cell stage, peaked in early blastocysts, and declined post-hatching.
- Soluble hepsin demonstrated concentration-dependent autoactivation, which was dependent on catalytic activity.
Conclusions:
- Hepsin is likely the first serine protease expressed during mammalian development.
- The autoactivation capability of hepsin is crucial for its function in early embryonic development.
- Hepsin represents a significant molecular marker for preimplantation embryonic development and potential early developmental processes.