Effect of Heavy Metals on Tyrosine Kinases Signaling during Sperm Capacitation

Abstract

Sperm capacitation is the key event prior to fertilization. Success rate of currently used assisted reproductive technology like in-vitro fertilization is 50% dependent on sperm maturation or capacitation. In-vivo capacitation occur almost in female reproductive tract in response to various signaling or enzymatic molecules. Interestingly, both early and late events of capacitation are centrally regulated by protein kinase A (PKA). Influx of Ca2+ and HCO3-transmembrane drive leads to change in pH and intracellular cAMP which ultimately activate PKA regulated capacitation. PKA phosphorylates several target proteins that are presumed to initiate different signaling pathways. Some divalent heavy metals like lead, mercury, arsenic and cadmium mimic Ca++ entry and its functions and ultimately affect capacitation by inhibiting or inducing tyrosine phosphorylation. In this chapter we review the mechanism of heavy metals by which they affect the tyrosine phosphorylation during sperm capacitation.