Signalling Events and Associated Pathways Related to the Mammalian Sperm Capacitation

Abstract

Capacitation is a biological phenomenon occurring prior to fertilization and is a multiple event process. Many physiological and biochemical changes takes place during the process; these changes are related to lipid composition of membrane, intracellular modulation of ion concentration, protein phosphorylation, sperm movement and membrane permeability. These events occur when the sperm is exposed to the new environment of ion concentration in the female reproductive tract. Ions such as bicarbonate and calcium facilitate capacitation by activating adenylyl cyclase, thus initiating protein kinase A (PKA) signalling cascade. Extracellular-regulated kinase pathway is activated by ligand binding to the membrane receptors and intracellular activation by reactive oxygen species (ROS). Activation of these pathways leads to the phosphorylation of different proteins, which is associated with events such as capacitation, hyperactivation and acrosome reaction that are essential for successful fertilization. Extensive studies were carried out on protein phosphorylation in relation to capacitation, but its role still remains ambiguous.

Changes in the Cellular Distribution of Tyrosine Phosphorylation and Its Relationship with the Acrosomal Exocytosis and Plasma Membrane Integrity during In Vitro Capacitation of Frozen/Thawed Bull Spermatozoa

“…Capacitation is a combination of physiological changes in the spermatozoa triggered within the female genital tract that is necessary for the acquisition of fertilizing competence [1]. This process comprises the activation of a complex intracellular signaling network [2,3] that leads to the phosphorylation of the tyrosine, serine, and threonine residues of multiple proteins at different cellular locations [1,4,5]. This signaling network is regulated by cAMP, protein kinase-A, as well as tyrosine kinase/phosphatase and serine/threonine kinase pathways [5,6].…”

Obesity, a serious etiologic factor for male subfertility in modern society

“…palmitoleic acid, oleic acid, linoleic acid, arachidonic acid, docosahexaenoic acid etc.). The fatty acid composition of spermatozoa is important for the sperm function, including sperm motility, viability and fertility (Aksoy et al 2006, Martinez-Soto et al 2013, Gangwar & Atreja 2015, Andersen et al 2016. The polyunsaturated fatty acids in spermatozoa, especially docosahexaenoic acid (DHA), are positively associated with sperm concentration, morphology and motility (Aksoy et al 2006, Tavilani et al 2007, Keber et al 2013.…”

Calpain inhibition prevents flotillin re-ordering and Src family activation during capacitation

“…During this time, several biochemical and physiological changes, collectively called capacitation, occur in the spermatozoa (Gangwar and Atreja 2015;Stival et al 2016). In mammalian sperm, capacitation is defined as a complex process that includes membrane modifications, enzyme activity modulation, cytoskeleton reorganization, membrane hyperpolarization and protein phosphorylation (Aitken and Nixon 2013;Gangwar and Atreja 2015).…”