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Specific modulation of cyclic ADP-ribose-induced Ca2+ release by polyamines
E N Chini1, K W Beers, C C Chini
1Department of Physiology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
The American Journal of Physiology
|October 1, 1995
Summary
Polyamines like spermine inhibit calcium release in sea urchin eggs mediated by cyclic ADP-ribose (cADPR). This suggests polyamines act as endogenous regulators of the cADPR-mediated calcium release system.
Area of Science:
- Cellular Biology
- Biochemistry
- Reproductive Biology
Background:
- Cyclic ADP-ribose (cADPR) is a key signaling molecule for calcium (Ca2+) release from intracellular stores.
- The precise regulatory mechanisms of cADPR-mediated Ca2+ release, particularly in fertilization, remain incompletely understood.
Purpose of the Study:
- To investigate the role of polyamines in regulating cADPR-induced Ca2+ release in sea urchin eggs.
- To determine the specificity of polyamine inhibition on different Ca2+ release pathways.
Main Methods:
- Sea urchin egg homogenates were used for bioassays.
- Calcium (Ca2+) release was measured using the indicator fluo 3.
- The effects of spermine, spermidine, and putrescine on Ca2+ release induced by cADPR, IP3, and NAADP were assessed.
Main Results:
- Physiological concentrations of spermine and related polyamines inhibited cADPR-induced Ca2+ release.
- Polyamines did not affect Ca2+ release induced by IP3 or NAADP, indicating pathway specificity.
- Spermine also inhibited Ca2+ release induced by caffeine and ryanodine.
- Pretreatment with caffeine or Sr2+/Ca2+ blocked spermine's inhibitory effect on cADPR-induced Ca2+ release.
Conclusions:
- Polyamines, particularly spermine, act as specific inhibitors of the ryanodine channel.
- Polyamines may function as endogenous regulators of the cADPR-mediated Ca2+ release system in fertilized sea urchin eggs.