Hyperpolarization induces cytosolic alkalization of mouse sperm flagellum probably through sperm Na+/H+ exchanger.

In Brief: Hyperpolarization of the membrane potential is a crucial step for mammalian sperm maturation. This work demonstrates that this membrane potential change likely activates a sperm-specific sodium/proton exchanger to induce alkalization in mouse sperm flagellum.

Abstract: The sperm-specific sodium/proton exchanger (sNHE) is an indispensable protein for male fertility in mammals.

Time-Lapse Flow Cytometry: A Robust Tool to Assess Physiological Parameters Related to the Fertilizing Capability of Human Sperm.

Plasma membrane (PM) hyperpolarization, increased intracellular pH (pH), and changes in intracellular calcium concentration ([Ca]) are physiological events that occur during human sperm capacitation. These parameters are potential predictors of successful outcomes for men undergoing artificial reproduction techniques (ARTs), but methods currently available for their determination pose various technical challenges and limitations. Here, we developed a novel strategy employing time-lapse flow cytometry (TLFC) to determine capacitation-related membrane potential () and pH changes, and progesterone-induced [Ca] increases.

TRPV4 activity regulates nuclear Ca and transcriptional functions of β-catenin in a renal epithelial cell model.

TRPV4 is a nonselective cationic channel responsive to several physical and chemical stimuli. Defects in TRPV4 channel function result in human diseases, such as skeletal dysplasias, arthropathies, and peripheral neuropathies. Nonetheless, little is known about the role of TRPV4 in other cellular functions, such as nuclear Ca homeostasis or Ca -regulated transcription.

Reactive oxygen species are involved in the signaling of equine sperm chemotaxis.

Sperm chemotaxis may facilitate the finding of the oocyte. Only capacitated spermatozoa can orient their movement by chemotaxis, which as well as capacitation, is regulated in part by the cAMP-PKA pathway. Reactive oxygen species (ROS) are produced during sperm capacitation which is closely related to chemotaxis.

Capacitation-associated alkalization in human sperm is differentially controlled at the subcellular level.

Capacitation in mammalian sperm involves the accurate balance of intracellular pH (pH), but the mechanisms controlling this process are not fully understood, particularly regarding the spatiotemporal regulation of the proteins involved in pH modulation. Here, we employed an image-based flow cytometry technique combined with pharmacological approaches to study pH dynamics at the subcellular level during capacitation. We found that, upon capacitation induction, sperm cells undergo intracellular alkalization in the head and principal piece regions.

Sperm physiology varies according to ultradian and infradian rhythms.

The spermatozoon must be physiologically prepared to fertilize the egg, process called capacitation. Human sperm samples are heterogeneous in their ability to capacitate themselves, which leads to variability between samples from the same or different donors, and even along the seasons. Here we studied sperm variation in the capacitation state according to the ability of capacitated spermatozoa to acrosome react upon stimulation (% ARi) and to be recruited by chemotaxis (% Chex).

Semi-automatized segmentation method using image-based flow cytometry to study sperm physiology: the case of capacitation-induced tyrosine phosphorylation.

Study Question: Is image-based flow cytometry a useful tool to study intracellular events in human sperm such as protein tyrosine phosphorylation or signaling processes?

Summary Answer: Image-based flow cytometry is a powerful tool to study intracellular events in a relevant number of sperm cells, which enables a robust statistical analysis providing spatial resolution in terms of the specific subcellular localization of the labeling.

What Is Known Already: Sperm capacitation is required for fertilization. During this process, spermatozoa undergo numerous physiological changes, via activation of different signaling pathways, which are not completely understood.