MRP4-mediated cAMP efflux is essential for mouse spermatozoa capacitation

ALONSO, C. A. I.; LOTTERO-LECONTE, R.; LUQUE, G. M.; VERNAZ, Z. J.; DI SIERVI, N.; GERVASI, M. G.; BUFFONE, M. G.; DAVIO, C.; PEREZ-MARTINEZ, S.

JOURNAL OF CELL SCIENCE

COMPANY OF BIOLOGISTS LTD

Año: 2019 vol. 132

0021-9533

Mammalian spermatozoa must undergo biochemical and structuralchanges to acquire the capacity for fertilization, in a process known ascapacitation. Activation of PKA enzymes is essential for capacitation,and thus cAMP levels are tightly regulated during this process.Previously, we demonstrated that during capacitation, bovinespermatozoa extrude cAMP through multidrug resistance-associatedprotein 4 (MRP4, also known as ABCC4), which regulates intracellularlevels of the nucleotide and provides cAMP to the extracellular space.Here, we report the presence of functional MRP4 in murinespermatozoa, since its pharmacological inhibition with MK571decreased levels of extracellular cAMP. This also produced a suddenincrease inPKAactivity, with decreased tyrosine phosphorylation at theend of capacitation. Blockade ofMRP4 inhibited induction of acrosomereaction, hyperactivation and in vitro fertilization. Moreover, MRP4inhibition generated an increase in Ca2+ levels mediated by PKA, anddepletion of Ca2+ salts from the medium prevented the loss of motilityand phosphotyrosine inhibition produced by MK571. These resultswere supported using spermatozoa from CatSper Ca2+ channelknockout mice. Taken together, these results suggest that cAMPefflux via MRP4 plays an essential role in mouse sperm capacitation.