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Updated: May 10, 2026
Collection of Post-mating Semen from the Female Reproductive Tract and Measurement of Semen Liquefaction in Mice
Published on: November 18, 2017
Proteomic analysis reveals a proteolytic feedback loop in murine seminal fluid
Chad M McKee1, Danmei Xu, Benedikt M Kessler
1Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford, UK.
Background:
Matrix metalloproteinase 9 (MMP9) has been implicated in extracellular matrix (ECM) remodelling, angiogenesis and inflammation. However, the targets for proteolysis that lead to these physiological consequences are often undefined as is the regulation of MMP9 itself. Therefore, identification of both the potential direct and indirect targets of MMP9 is critical for further understanding the effects of its proteolytic cascades.
Methods:
To study these cascades on a wider scale, transgenic mouse "knock-out" models and ultra-high performance liquid chromatography mass spectroscopy (UPLC-MS(E) ) were used to elucidate the MMP9 targets, inhibitors, and interactors found in mouse seminal vesicle fluid (SVF).
Results:
Proteomics analysis of SVF from wild type, mmp9-/- or pn1-/- mice detected differences in serine protease inhibitors (serpins), reproductive proteins, developmental regulators, and cancer proto-oncogenes, including Renin 1/2. Protease nexin 1 (PN1), an ECM-based inhibitor of urokinase, was elevated in the SVF of mmp9-/- mice. We observed that MMP9-mediated N-terminal cleavage of PN1 reduces this serpin's functional activity. Our data also suggest a feedback loop in which inhibition of PN1 is a critical step in permitting greater activity of MMP9.
Conclusion:
This study extends the degradome of MMP9 and examines components relevant to seminal fluid physiology. PN1 is proposed to be a novel inhibitor of MMP9 activity and a block to collagen cleavage, a frequent antecedent to cancer cell invasion. The interaction of MMP9 with PN1 and other serpins may lead to a better understanding of seminal vesicle function and possible impacts on fertility, as well as provide novel therapeutic targets.
Insights
Matrix metalloproteinase 9 (MMP9) targets Protease Nerin 1 (PN1), an inhibitor that blocks collagen breakdown. This interaction is key to understanding MMP9's role in seminal vesicle function and potential therapeutic strategies.
Area of Science:
- Biochemistry
- Proteomics
- Molecular Biology
Background:
- Matrix metalloproteinase 9 (MMP9) influences extracellular matrix remodeling, angiogenesis, and inflammation.
- Understanding MMP9's specific targets and regulation is crucial for elucidating its physiological roles.
- Identifying MMP9 targets is critical for understanding its proteolytic cascades.
Purpose of the Study:
- To identify MMP9 targets, inhibitors, and interactors in mouse seminal vesicle fluid (SVF).
- To investigate the interaction between MMP9 and Protease Nerin 1 (PN1).
- To explore the implications of MMP9-PN1 interaction on seminal vesicle function and fertility.
Main Methods:
- Utilized transgenic mouse models (wild type, mmp9-/-, pn1-/-).
- Employed ultra-high performance liquid chromatography mass spectroscopy (UPLC-MS(E)) for proteomics analysis.
- Analyzed SVF to detect differences in protein composition.
Main Results:
- Proteomics analysis revealed differences in serine protease inhibitors (serpins), reproductive proteins, developmental regulators, and cancer proto-oncogenes.
- Protease Nerin 1 (PN1) was elevated in mmp9-/- mice, and MMP9 mediated its N-terminal cleavage, reducing its activity.
- A feedback loop was suggested where PN1 inhibition enhances MMP9 activity.
Conclusions:
- This study expands the known targets of MMP9 within seminal vesicle fluid.
- Protease Nerin 1 (PN1) is identified as a novel inhibitor of MMP9 activity and collagen cleavage.
- The interaction between MMP9 and PN1 may offer insights into seminal vesicle function, fertility, and potential therapeutic targets.
