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FXII promotes proteolytic processing of the LRP1 ectodomain
Lukasz Wujak1, Christina Hesse2, Katherina Sewald2
1Department of Biochemistry, Universities of Giessen and Marburg Lung Center, Giessen, Germany.
Factor XII (FXII) processes the low-density lipoprotein receptor-related protein 1 (LRP1) ectodomain, impacting cell surface protein levels. This FXII-dependent LRP1 processing may drive pathological tissue remodeling.
Area of Science:
- Biochemistry
- Cell Biology
- Proteolysis
Background:
- Factor XII (FXII) is a serine protease involved in coagulation, kallikrein-kinin, and complement systems.
- FXII binding to cell surfaces is known, but its role in processing membrane-anchored proteins was undescribed.
Purpose of the Study:
- To investigate the effect of FXII on the proteolytic processing of the low-density lipoprotein receptor-related protein 1 (LRP1) ectodomain.
- To elucidate the mechanism and consequences of FXII-mediated LRP1 processing.
Main Methods:
- Tested FXII's effect on LRP1 ectodomain processing in human lung fibroblasts, alveolar macrophages, and lung slices.
- Confirmed LRP1 fragment identity using MALDI-TOF-MS.
- Measured FXII and gelatinase activity via S-2302 hydrolysis and zymography.
Main Results:
- FXII directly processed the LRP1 ectodomain, leading to fragment accumulation in conditioned media.
- This processing was FXII proteolytic activity-dependent and independent of metalloproteases.
- FXII binding to cells activated FXII and was linked to gelatinase (MMP-2, MMP-9) accumulation.
Conclusions:
- FXII regulates LRP1 levels and function by modulating its ectodomain processing.
- FXII-dependent LRP1 processing could exacerbate extracellular proteolysis and promote pathological tissue remodeling.
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