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A+-Helix of Protein C Inhibitor (PCI) Is a Cell-penetrating Peptide That Mediates Cell Membrane Permeation of PCI*
- Source :
- The Journal of Biological Chemistry
- Publication Year :
- 2014
- Publisher :
- American Society for Biochemistry and Molecular Biology, 2014.
-
Abstract
- Background: Extracellular protein C inhibitor (PCI) can cross the cellular plasma membrane. Results: Testisin (fluid-phase and cell membrane-anchored) cleaves PCI close to its N terminus. N-terminally truncated PCI can no longer be internalized by cells. Conclusion: Testisin removes helix A+, a cell-penetrating peptide, which mediates cell membrane permeation of PCI. Significance: Testisin or other proteases could regulate PCI internalization by removing its N terminus.<br />Protein C inhibitor (PCI) is a serpin with broad protease reactivity. It binds glycosaminoglycans and certain phospholipids that can modulate its inhibitory activity. PCI can penetrate through cellular membranes via binding to phosphatidylethanolamine. The exact mechanism of PCI internalization and the intracellular role of the serpin are not well understood. Here we showed that testisin, a glycosylphosphatidylinositol-anchored serine protease, cleaved human PCI and mouse PCI (mPCI) at their reactive sites as well as at sites close to their N terminus. This cleavage was observed not only with testisin in solution but also with cell membrane-anchored testisin on U937 cells. The cleavage close to the N terminus released peptides rich in basic amino acids. Synthetic peptides corresponding to the released peptides of human PCI (His1–Arg11) and mPCI (Arg1–Ala18) functioned as cell-penetrating peptides. Because intact mPCI but not testisin-cleaved mPCI was internalized by Jurkat T cells, a truncated mPCI mimicking testisin-cleaved mPCI was created. The truncated mPCI lacking 18 amino acids at the N terminus was not taken up by Jurkat T cells. Therefore our model suggests that testisin or other proteases could regulate the internalization of PCI by removing its N terminus. This may represent one of the mechanisms regulating the intracellular functions of PCI.
- Subjects :
- Serpin
Cell Membrane Permeability
Nuclear Translocation
Serine Endopeptidases
Cell Biology
Cell-Penetrating Peptides
U937 Cells
GPI-Linked Proteins
Cell-penetrating Peptide (CPP)
Testisin
Mice
surgical procedures, operative
Cell Line, Tumor
Animals
Humans
cardiovascular diseases
Cell Permeabilization
Peptides
therapeutics
Protein C Inhibitor
Subjects
Details
- Language :
- English
- ISSN :
- 1083351X and 00219258
- Volume :
- 290
- Issue :
- 5
- Database :
- OpenAIRE
- Journal :
- The Journal of Biological Chemistry
- Accession number :
- edsair.pmid..........3953fa491d8ba2b2521155dbf02daa0c