Investigation into the Role of Phosphatidylserine in Modifying the Susceptibility of Human Lymphocytes to Secretory Phospholipase A2 using Cells Deficient in the Expression of Scramblase
| Autor: | Ryan Baker, Sarah Franklin, John D. Bell, Amy Hamaker, Lynn Anderson, Jennifer Nelson, Mikayla Orton, Celestine H.-Y. Yeung, Eric G. Moss, Evan Stevens, Izadora Izidoro, Joseph Chen, Lyndee L. Francom, Allan M. Judd, Kelly L. Damm |
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| Jazyk: | angličtina |
| Předmět: |
Phospholipid scramblase
Cell Biophysics Biological Transport Active Phosphatidylserines Secretory phospholipase A2 Biochemistry Gene Expression Regulation Enzymologic Article Cell membrane Mice 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Phospholipase A2 Cell Line Tumor hemic and lymphatic diseases medicine Merocyanine 540 Animals Humans Lymphocytes Trimethylammonium diphenylhexatriene Phospholipid Transfer Proteins Phospholipases A2 Secretory Biophysical membrane change 030304 developmental biology 0303 health sciences biology Phosphatidylserine exposure Hydrolysis Cell Membrane 030302 biochemistry & molecular biology Cell Biology Phosphatidylserine Cell biology Raji cell medicine.anatomical_structure chemistry Cell culture Ionomycin biology.protein 030217 neurology & neurosurgery |
| Zdroj: | Biophysical Journal. (3):78a |
| ISSN: | 0006-3495 |
| DOI: | 10.1016/j.bpj.2011.11.452 |
| Popis: | Normal human lymphocytes resisted the hydrolytic action of secretory phospholipase A2 but became susceptible to the enzyme following treatment with a calcium ionophore, ionomycin. To test the hypothesis that this susceptibility requires exposure of the anionic lipid phosphatidylserine on the external face of the cell membrane, experiments were repeated with a human Burkitt's lymphoma cell line (Raji cells). In contrast to normal lymphocytes or S49 mouse lymphoma cells, most of the Raji cells (83%) did not translocate phosphatidylserine to the cell surface upon treatment with ionomycin. Those few that did display exposed phosphatidylserine were hydrolyzed immediately upon addition of phospholipase A2. Interestingly, the remaining cells were also completely susceptible to the enzyme but were hydrolyzed at a slower rate and after a latency of about 100s. In contradistinction to the defect in phosphatidylserine translocation, Raji cells did display other physical membrane changes upon ionomycin treatment that may be relevant to hydrolysis by phospholipase A2. These changes were detected by merocyanine 540 and trimethylammonium diphenylhexatriene fluorescence and were common among normal lymphocytes, S49 cells, and Raji cells. The levels of these latter effects corresponded well with the relative rates of hydrolysis among the three cell lines. These results suggested that while phosphatidylserine enhances the rate of cell membrane hydrolysis by secretory phospholipase A2, it is not an absolute requirement. Other physical properties such as membrane order contribute to the level of membrane susceptibility to the enzyme independent of phosphatidylserine. |
| Databáze: | OpenAIRE |
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