Zinc: A small molecule with a big impact on sperm function

Abstract

Zinc is an essential mineral, but our understanding of its uses in the body is limited. Capitalizing on approaches available in the model system Caenorhabditis elegans, Zhao and colleagues show that zinc transduces a signal that induces sperm to become motile. This is an enigmatic process because sperm in all sexually-reproducing animals are transcriptionally inactive. Zinc levels inside sperm are regulated by an evolutionarily conserved zinc transporter called Zrt- and Irt-like Protein Transporter 7.1 (ZIPT-7.1). This zinc transporter localizes to intracellular organelles, suggesting that it primarily controls zinc levels by releasing zinc into the cytoplasm from internal stores rather than importing it from the external environment. The zinc released within cells acts as a messenger in a signaling pathway to promote mobility acquisition. These studies reveal an important role for zinc as an intracellular second messenger that generates physiological changes vital for sperm motility and fertility.

Metabolite Support of Long-Term Storage of Sperm in the Spermatheca of Honeybee (Apis mellifera) Queens

“…In the present work, a downward trend in acetylation was observed in sperm stored in the spermatheca ( Supplementary Table S8 ). After transfer into the spermatheca, stored sperm is generally assumed to be inactive until activated during fertilization by Zrt- and Irt-like protein transporter 7.1 (ZIPT-7.1) ( Zhao et al, 2018 ) (not detected in the present study) and mineral zinc ( Chu, 2018 ).…”

“…In the present work, a downward trend in acetylation was observed in sperm stored in the spermatheca ( Supplementary Table S8). After transfer into the spermatheca, stored sperm is generally assumed to be inactive until activated during fertilization by Zrt-and Irt-like protein transporter 7.1 (ZIPT-7.1) (Zhao et al, 2018) (not detected in the present study) and mineral zinc (Chu, 2018). Sakaguchi et al (2009) studied bovine sperm-oocyte interactions and discovered that supplementary N-acetyl-Dglucosamine (GlcNAc) (at 5 or 25 mM) significantly suppresses the number of sperm that attach to the zona pellucida (Sakaguchi et al, 2009).…”

The Role of Zinc in Male Fertility

“…Thus, Zn 2+ acts as a second messenger that modulates sperm functions, including motility and capacitation. This suggests that intracellular Zn 2+ levels should be well-controlled by zinc transporters localized at intracellular membranes and in the cell plasma membrane, which import Zn 2+ from the external environment [ 62 ].…”

“…However, in sea urchin, a treatment with ethylenediamine tetra acetic acid (EDTA), a bivalent metal ion chelator, inhibits sperm motility, an effect that was reversed by the addition of Zn 2+ [ 65 ]. In C. elegans , the zinc released within cells acts as a messenger in a signaling pathway to promote mobility acquisition [ 62 ]. Thus, extracellular Zn 2+ affects sperm motility, but whether its effect is inhibitory or stimulatory seems to be species- and concentration-dependent, whereby relatively low Zn 2+ concentrations stimulate motility, whereas high Zn 2+ inhibits sperm motility.…”

Sperm Cohort-Specific Zinc Signature Acquisition and Capacitation-Induced Zinc Flux Regulate Sperm-Oviduct and Sperm-Zona Pellucida Interactions

“…It is widely understood that zinc ions (Zn 2+ ) play an important role in male fertility, in species ranging from with C. elegans [1] through higher order mammals [2][3][4] (for review, see [5][6][7]), but its role in creating subpopulations of fertilization competent spermatozoa was not known until the discovery of the zinc signature in boar, bull, and human spermatozoa [8]. Although pre-requisite for fertility [9,10], sperm capacitation is a terminal maturation event leading to rapid cell death unless fertilization occurs [11].…”