Participación del proceso de exclusión de AMPc a través del transportador MRP4 en regulación de la función espermática en mamíferos

PEREZ MARTINEZ S

Simposio; II Jornadas LabBA; 2018

In order to fertilize an oocyte, mammalian spermatozoamust undergo a number of physiological modifications inthe female reproductive tract, collectively known as capacitation.Activation of PKA is essential for capacitation,and therefore cAMP levels are tightly regulated during thisprocess. Although cAMP levels are mainly determinedby its synthesis and degradation, we previously demonstratedthat cAMP extrusion through multidrug resistanceprotein 4 (MRP4) is also involved in this modulation inbovine sperm capacitation. Moreover, supplementationof incubation media with non-permeable-cAMP triggerscapacitation, suggesting that cAMP efflux is necessaryto regulate intracellular nucleotide levels and to providethe extracellular space with molecules that promote purinergicsignalling.Our aim was to deepen the role of cAMP/MRP4 effluxsystem in mammalian sperm capacitation. For this, wepropose 1) to elucidate molecular pathways involvedin extracellular cAMP-induced in bovine sperm capacitation;2) to evaluate the possible role of cAMP/MRP4efflux in mouse sperm capacitation.Bovine spermatozoa were incubated in non-capacitatingmedia with non-permeable-cAMP (ecAMP; 10nM)and enzymes inhibitors of purinergic signaling pathways,and changes associated with capacitation wereassessed. Our results indicated that ecAMP exerts arobust response in bovine sperm capacitation activatingPLC, PKC and ERK-1/2. Additionally, ecAMP elicited afast rise in sperm Ca2+ levels that activated sAC and increasedpPKA and pY levels, indicating that cAMP exertsa broad range of responses in this species.On the other hand, mouse spermatozoa were incubatedin capacitating conditions with MK571 (MRP4 inhibitor)and changes associated with capacitation wereassessed. MRP4 inhibition increased intracellular cAMPand pPKA levels. However, MK571 inhibited sperm motility,hyperactivation, induced-acrosomal reaction and invitro fertilization.Our results suggest that cAMP/MRP4 efflux-system hasa critical role in the regulation of cAMP-activated signallingpathways in both species and emerges as an importantplayer in sperm physiology.