TRPM8, a versatile channel in human sperm.
BACKGROUND
The transient receptor potential channel (TRP) family includes more than 30 proteins; they participate in various Ca(2+) dependent processes. TRPs are functionally diverse involving thermal, chemical and mechanical transducers which modulate the concentration of intracellular Ca(2+) ([Ca(2+)]i). Ca(2+) triggers and/or regulates principal sperm functions during fertilization such as motility, capacitation and the acrosome reaction. Nevertheless, the presence of the TRPM subfamily in sperm has not been explored.


RESULTS
Here we document with RT-PCR, western blot and immunocitochemistry analysis the presence of TRPM8 in human sperm. We also examined the participation of this channel in sperm function using specific agonists (menthol and temperature) and antagonists (BCTC and capsazepine). Computer-aided sperm analysis revealed that menthol did not significantly alter human sperm motility. In contrast, menthol induced the acrosome reaction in human sperm. This induction was inhibited about 70% by capsazepine (20 microM) and 80% by BCTC (1.6 microM). Activation of TRPM8 either by temperature or menthol induced [Ca(2+)]i increases in human sperm measured by fluorescence in populations or individual sperm cells, effect that was also inhibited by capsazepine (20 microM) and BCTC (1.6 microM). However, the progesterone and ZP3-induced acrosome reaction was not inhibited by capsazepine or BCTC, suggesting that TRPM8 activation triggers this process by a different signaling pathway.


CONCLUSIONS
This is the first report dealing with the presence of a thermo sensitive channel (TRPM8) in human sperm. This channel could be involved in cell signaling events such as thermotaxis or chemotaxis.
De Blas
Gerardo A
GA
Departmento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México.
Darszon
Alberto
A
Ocampo
Ana Y
AY
Serrano
Carmen J
CJ
Castellano
Laura E
LE
Hernández-González
Enrique O
EO
Chirinos
Mayel
M
Larrea
Fernando
F
Beltrán
Carmen
C
Treviño
Claudia L
CL
D020101:Acrosome Reaction; D002118:Calcium / Q000378:metabolism; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D002633:Chemotaxis; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008297:Male; D008954:Models, Biological; D011374:Progesterone / Q000378:metabolism; D011719:Pyrazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013081:Sperm Motility; D013094:Spermatozoa / Q000378:metabolism*; D050053:TRPM Cation Channels / Q000378:metabolism / Q000502:physiology*
C475772:N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl)tetrahydropyrazine-1(2H)-carboxamide; D011719:Pyrazines; D011725:Pyridines; D050053:TRPM Cation Channels; C425966:TRPM8 protein, human; D011374:Progesterone; C071423:capsazepine; D002211:Capsaicin; D002118:Calcium