Mitochondria and mammalian reproduction

Abstract

Mitochondria are cellular organelles with crucial roles in ATP synthesis, metabolic integration, reactive oxygen species (ROS) synthesis and management, the regulation of apoptosis (namely via the intrinsic pathway), among many others. Additionally, mitochondria in different organs or cell types may have distinct properties that can decisively influence functional analysis. In terms of the importance of mitochondria in mammalian reproduction, and although there are species-specific differences, these aspects involve both energetic considerations for gametogenesis and fertilization, control of apoptosis to ensure the proper production of viable gametes, and ROS signaling, as well as other emerging aspects. Crucially, mitochondria are the starting point for steroid hormone biosynthesis, given that the conversion of cholesterol to pregnenolone (a common precursor for all steroid hormones) takes place via the activity of the cytochrome P450 side-chain cleavage enzyme (P450scc) on the inner mitochondrial membrane. Furthermore, mitochondrial activity in reproduction has to be considered in accordance with the very distinct strategies for gamete production in the male and female. These include distinct gonad morpho-physiologies, different types of steroids that are more prevalent (testosterone, estrogens, progesterone), and, importantly, the very particular timings of gametogenesis. While spermatogenesis is complete and continuous since puberty, producing a seemingly inexhaustible pool of gametes in a fixed environment; oogenesis involves the episodic production of very few gametes in an environment that changes cyclically. These aspects have always to be taken into account when considering the roles of any common element in mammalian reproduction.

Loss of flavin adenine dinucleotide (FAD) impairs sperm function and male reproductive advantage inC. elegans

“…Altered mitochondrial structure and activity have been correlated with sperm dysfunction across different species (Amaral, Lourenco, Marques, & Ramalho-Santos; Liau, Gonzalez-Serricchio, Deshommes, Chin, & LaMunyon; Nakada et al; Ramalho-Santos & Amaral). In addition, proper sperm function requires low levels of ROS (de Lamirande & Gagnon; Kodama, Kuribayashi, & Gagnon; Leclerc, de Lamirande, & Gagnon), although a specific role for endogenous mitochondrial derived ROS is undefined.…”

Sperm mitochondrial regulation in motility and fertility in horses

“…Equine sperm each contain 40-50 mitochondria in the midpiece composed of single mitochondria that line up end to end during spermiogenesis (Ho & Wey, 2007;Ramalho-Santos & Amaral, 2013;Varner & Johnson, 2011). Functions of mitochondria in sperm include ATP production for motility, reactive oxygen species (ROS) production, apoptosis and calcium homoeostasis (Peña et al, 2009;Ramalho-Santos & Amaral, 2013).…”

“…Equine sperm each contain 40-50 mitochondria in the midpiece composed of single mitochondria that line up end to end during spermiogenesis (Ho & Wey, 2007;Ramalho-Santos & Amaral, 2013;Varner & Johnson, 2011). Functions of mitochondria in sperm include ATP production for motility, reactive oxygen species (ROS) production, apoptosis and calcium homoeostasis (Peña et al, 2009;Ramalho-Santos & Amaral, 2013). Equine sperm possess machinery for the cellular processes of glycolysis, the citric acid cycle and oxidative phosphorylation (OxPhos) to meet the large energy requirements for motility and the subsequent hyperactivated motility that is required for sperm to fertilize an egg (Moraes & Meyers, 2018).…”

A Role for the Respiratory Chain in Regulating Meiosis Initiation in Saccharomyces cerevisiae

“…participate in various cellular functions during gametogenesis, such as hormone synthesis (Ramalho-Santos and Amaral 2013), apoptosis (Mishra et al 2006;Tiwari et al 2015), reactive oxygen species production (Lu et al 2008), and the integration of metabolic to signaling pathways (Amaral et al 2013;Mishra and Chan 2014;Tiwari et al 2015).…”