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Cytotoxicity induced in myotubes by a Lys49 phospholipase A2 homologue from the venom of the snake Bothrops asper: evidence of rapid plasma membrane damage and a dual role for extracellular calcium.
- Source :
-
Toxicology in vitro : an international journal published in association with BIBRA [Toxicol In Vitro] 2007 Dec; Vol. 21 (8), pp. 1382-9. Date of Electronic Publication: 2007 Apr 29. - Publication Year :
- 2007
-
Abstract
- Acute muscle tissue damage, myonecrosis, is a typical consequence of envenomations by snakes of the family Viperidae. Catalytically-inactive Lys49 phospholipase A(2) homologues are abundant myotoxic components in viperid venoms, causing plasma membrane damage by a mechanism independent of phospholipid hydrolysis. However, the precise mode of action of these myotoxins remains unsolved. In this work, a cell culture model of C2C12 myotubes was used to assess the action of Bothrops asper myotoxin II (Mt-II), a Lys49 phospholipase A(2) homologue. Mt-II induced a dose- and time-dependent cytotoxic effect associated with plasma membrane disruption, evidenced by the release of the cytosolic enzyme lactate dehydrogenase and the penetration of propidium iodide. A rapid increment in cytosolic Ca(2+) occurred after addition of Mt-II. Such elevation was associated with hypercontraction of myotubes and blebbing of plasma membrane. An increment in the Ca(2+) signal was observed in myotube nuclei. Elimination of extracellular Ca(2+) resulted in increased cytotoxicity upon incubation with Mt-II, suggesting a membrane-protective role for extracellular Ca(2+). Chelation of cytosolic Ca(2+) with BAPTA-AM did not modify the cytotoxic effect, probably due to the large increment induced by Mt-II in cytosolic Ca(2+) which overrides the chelating capacity of BAPTA-AM. It is concluded that Mt-II induces rapid and drastic plasma membrane lesion and a prominent Ca(2+) influx in myotubes. Extracellular Ca(2+) plays a dual role in this model: it protects the membrane from the cytolytic action of the toxin; at the same time, the Ca(2+) influx that occurs after membrane disruption is likely to play a key role in the intracellular degenerative events associated with Mt-II-induced myotube damage.
- Subjects :
- Animals
Cell Line
Cytosol metabolism
Mice
Muscle, Skeletal cytology
Bothrops physiology
Calcium metabolism
Crotalid Venoms toxicity
Group II Phospholipases A2 chemistry
Group II Phospholipases A2 toxicity
Muscle Fibers, Skeletal drug effects
Reptilian Proteins chemistry
Reptilian Proteins toxicity
Subjects
Details
- Language :
- English
- ISSN :
- 0887-2333
- Volume :
- 21
- Issue :
- 8
- Database :
- MEDLINE
- Journal :
- Toxicology in vitro : an international journal published in association with BIBRA
- Publication Type :
- Academic Journal
- Accession number :
- 17560765
- Full Text :
- https://doi.org/10.1016/j.tiv.2007.04.010