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Enrichment of Extracellular Matrix Proteins from Tissues and Digestion into Peptides for Mass Spectrometry Analysis
Published on: July 23, 2015
Secreted cathepsin L generates endostatin from collagen XVIII
U Felbor1, L Dreier, R A Bryant
1Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
The EMBO Journal
|March 16, 2000
Summary
Cathepsin L secreted by tumor cells generates endostatin, an angiogenesis inhibitor, at acidic pH. This suggests cathepsin L
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Endostatin is a potent inhibitor of angiogenesis and tumor growth.
- Endostatin was originally identified in murine hemangioendothelioma (EOMA) cell-conditioned media.
- N-terminal sequencing revealed endostatin as a fragment of basement membrane collagen XVIII.
Purpose of the Study:
- To elucidate the specific enzymes responsible for endostatin generation.
- To investigate the role of pH in endostatin processing.
- To explore the potential role of cathepsin L in angiogenesis.
Main Methods:
- N-terminal amino acid sequencing of endostatin.
- Analysis of conditioned media from EOMA cells.
- Enzyme activity assays under varying pH conditions.
Main Results:
- Cathepsin L, secreted by EOMA cells, generates endostatin with the predicted N-terminus.
- Metalloproteases produce larger collagen XVIII fragments via a parallel pathway.
- Efficient endostatin generation occurs at moderately acidic pH, mimicking the tumor microenvironment.
- Secretion of cathepsin L by an endothelial tumor cell line suggests its involvement in angiogenesis.
Conclusions:
- Cathepsin L is a key enzyme in endostatin generation.
- Tumor acidity facilitates endostatin production.
- Cathepsin L may play a significant role in tumor angiogenesis.
- Collagen XVIII processing is regulated by proteolysis, potentially controlling angiogenesis.
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