Scorpion toxins that block T-type Ca2+ channels in spermatogenic cells inhibit the sperm acrosome reaction.
The acrosome reaction (AR) is a Ca(2+)-dependent event required for sperm to fertilize the egg. The activation of T-type voltage-gated Ca(2+) channels plays a key role in the induction of this process. This report describes the actions of two toxins from the scorpion Parabuthus granulatus named kurtoxin-like I and II (KLI and KLII, respectively) on sperm Ca(2+) channels. Both toxins decrease T-type Ca(2+) channel activity in mouse spermatogenic cells and inhibit the AR in mature sperm. Saturating concentrations of the toxins inhibited at most approximately 70% of the whole-cell Ca(2+) current, suggesting the presence of a toxin-resistant component. In addition, both toxins inhibited approximately 60% of the AR, which is consistent with the participation of T-type Ca(2+) channels in the sperm AR.
López-González
Ignacio
I
Department of Development Genetics and Molecular Physiology, Institute of Biotechnology, National Autonomous University of Mexico, Avenida Universidad 2001, Col. Chamilpa, CP 62100, Cuernavaca, Mor., Mexico.
Olamendi-Portugal
Timoteo
T
De la Vega-Beltrán
José L
JL
Van der Walt
Jurg
J
Dyason
Karin
K
Possani
Lourival D
LD
Felix
Ricardo
R
Darszon
Alberto
A
D020101:Acrosome Reaction / Q000187:drug effects*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020747:Calcium Channels, T-Type / Q000502:physiology*; D002478:Cells, Cultured; D004553:Electric Conductivity; D007700:Kinetics; D008297:Male; D051379:Mice; D009498:Neurotoxins / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D012604:Scorpion Venoms / Q000494:pharmacology*; D013093:Spermatogonia / Q000187:drug effects / Q000502:physiology; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology
D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type; D009498:Neurotoxins; D012604:Scorpion Venoms; C118444:kurtoxin