Roles of Intracellular Cyclic AMP Signal Transduction in the Capacitation and Subsequent Hyperactivation of Mouse and Boar Spermatozoa

Abstract

It is not until accomplishment of a variety of molecular changes during the transit through the female reproductive tract that mammalian spermatozoa are capable of exhibiting highly activated motility with asymmetric whiplash beating of the flagella (hyperactivation) and undergoing acrosomal exocytosis in the head (acrosome reaction). These molecular changes of the spermatozoa are collectively termed capacitation and promoted by bicarbonate, calcium and cholesterol acceptors. Such capacitation-promoting factors can stimulate intracellular cyclic AMP (cAMP) signal transduction in the spermatozoa. Meanwhile, hyperactivation and the acrosome reaction are essential to sperm fertilization with oocytes and are apparently triggered by a sufficient increase of intracellular Ca2+ in the sperm flagellum and head, respectively. Thus, it is necessary to investigate the relationship between cAMP signal transduction and calcium signaling cascades in the spermatozoa for the purpose of understanding the molecular basis of capacitation. In this review, I cover updated insights regarding intracellular cAMP signal transduction, the acrosome reaction and flagellar motility in mammalian spermatozoa and then account for possible roles of intracellular cAMP signal transduction in the capacitation and subsequent hyperactivation of mouse and boar spermatozoa.

Protein biomarkers for male artificial insemination subfertility in bovine spermatozoa

“…Specifically, the sperm plasma membrane becomes unstable from the release of decapacitation factors during the early stage of capacitation 78, 79. The intracellular signal transduction systems gradually become active and promote the increase of pH i , protein phosphorylation, and membrane hyperpolarization during both the early and the late stages in order to induce the entry of the external Ca 2+ and release of the internal Ca 2+ from the store 80, 81. In the case of considering Chang's meaning of capacitation, moreover, it is preferable to include the Ca 2+ ‐triggered events of hyperactivation and acrosome reaction in the capacitation process 82…”

“…It has been believed for a long time that the progress of the capacitation process is coincident with the increase of tyrosine‐phosphorylated proteins in mammals, including cattle,84, 85, 86 although the detailed functions of the tyrosine‐phosphorylated proteins are poorly understood in the fertilization‐related events of bull spermatozoa 87. This event is regulated pivotally by the intracellular cyclic adenosine monophosphate (cAMP) signaling cascades that are composed of the bicarbonate/Ca 2+ ‐activated adenylyl cyclase (a soluble‐type of adenylyl cyclase, ADCY10), protein kinase A (PKA), protein phosphatases, and protein tyrosine kinases 81, 88, 89, 90. Moreover, various ion channels and pumps play regulatory roles in the multiple changes during capacitation 91, 92, 93.…”

Sperm Capacitation and Acrosome Reaction in Mammalian Sperm

“…This review will focus on the signaling events involved in the regulation of the changes in the sperm membrane potential that occur during capacitation and their connection with the acrosome reaction. For more information regarding capacitation, see other reviews on this topic (Aitken and Nixon 2013;Buffone et al 2014;Harayama 2013;Bailey 2010). Discussion of the acrosome reaction and the molecular mechanisms involved in this event can be found in different chapters of this book.…”

Effect of calmodulin on the stimulation of capacitation and acrosome reaction of frozen thawed bull spermatozoa

“…Mammalian spermatozoa undergo a variety of physiological and biochemical modifications during their transit through female reproductive tract (Harayama, 2013). These changes are collectively termed "capacitation" and regulated by sperm interaction with fe reproductive tract (Kuo et al, 2016).…”

“…201 Artificial insemination is the most widely applied tool in modern animal breeding and thereby facilitating extensive utilization of cryopreserved spermatozoa. Mammalian spermatozoa undergo a variety of physiological and biochemical ir transit through female reproductive tract (Harayama, 2013). These changes are collectively termed "capacitation" sperm interaction with female ., 2016).…”