Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.64898/2026.09.28.755036

Mitochondrial Calcium Uptake Promotes Mitochondrial Activation and Hyperactivated Motility During Human Sperm Capacitation

Irigoyen, P.·Ferreira, J. J.·Cassina, A.·Bhagwat, S. M.·Peramsetty, N.·Sapiro, R.·Santi, C. M.
View original source ↗Export metadata ↓

Abstract

Capacitation is a post-ejaculatory maturation process by which sperm become hyperactive and undergo the acrosome reaction, both of which are required to fertilize an oocyte. Two key features of capacitation are increased intracellular calcium via the calcium channel CatSper and changes in mitochondrial function. In mouse spermatozoa, CatSper-dependent calcium entry promotes mitochondrial calcium uptake and mitochondrial activation, contributing to hyperactivated motility and fertilization ability. Whether this mechanism is conserved in human spermatozoa was unknown. Here, we assessed mitochondrial function and mitochondrial calcium in paired non-capacitated and capacitated human spermatozoa from normozoospermic donors. Capacitation increased mitochondrial respiratory control ratio, coupling efficiency, mitochondrial membrane potential, and mitochondrial calcium. The increase in mitochondrial calcium required extracellular calcium and was prevented by pharmacological inhibition of CatSper or the mitochondrial calcium uniporter (MCU). Inhibition of CatSper or mitochondrial calcium uniporter also attenuated the capacitation-associated increase in mitochondrial membrane potential and reduced hyperactivated motility without affecting progressive or total motility. Pharmacological disruption of mitochondrial function reduced capacitation-associated hyperactivated motility without affecting the acrosome reaction. Together, these findings support a conserved pathway in human and mouse spermatozoa in which CatSper-mediated calcium entry promotes MCU-dependent mitochondrial calcium uptake and mitochondrial activation, contributing to the acquisition of hyperactivated motility during capacitation. These findings identify mitochondrial calcium handling as a potential target for modulating human spermatozoa function.

Explore related subjects

physiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Irigoyen, P., Ferreira, J. J., Cassina, A., Bhagwat, S. M., Peramsetty, N., Sapiro, R., Santi, C. M.. 2026-10-02. Mitochondrial Calcium Uptake Promotes Mitochondrial Activation and Hyperactivated Motility During Human Sperm Capacitation. https://doi.org/10.64898/2026.09.28.755036

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

A conserved cold stress syndrome defines insect chill tolerance

The ability to withstand cold is arguably one of the most important traits defining the biogeographical distribution of insects. For most species, those classified as chill susceptible, cold tolerance is limited by the ability to maintain vital physiological functions at low temperature. However, there is currently no unified understanding of how physiological failure develops during cold stress or how this process explains variation in cold sensitivity within and among species. Although disruption of ion homeostasis has been implicated in chilling injury, it remains unclear whether it represents a common physiological limit across cold stress intensities and degrees of chill tolerance. Here, we tested whether ion balance disruption represents a unifying physiological syndrome of chill susceptibility by simultaneously quantifying cold mortality and hemolymph [K] in Drosophila. We examined this relationship across i) a broad range of cold stress intensities, ii) 25 species spanning extensive variation in cold sensitivity, biogeography and phylogeny, and iii) acclimation groups of D. melanogaster developed between 12 and 27{degrees}C. Across all comparisons, mortality was associated with the same cold-stress response, characterized by progressive hyperkalemia and mortality following a ~150% increase in hemolymph [K] above baseline ([K]crit). In contrast, adaptive and plastic variation in cold sensitivity was explained by differences in the critical temperature at which ion homeostasis failed (Tc). Extending this framework to published data from other insect orders revealed a remarkably similar [K]crit, suggesting that ionoregulatory collapse represents a conserved physiological constraint defining insect cold survival.

physiology↗
bioRxiv2026

Development of a mouse model to investigate the effect of exertional heat stress on skeletal muscle

Increased body temperature during exercise is considered a risk factor for skeletal muscle injury. There are various murine models of heat exposure-induced organ injury. The present study has attempted to develop a mouse model of skeletal muscle injury associated with exercise-induced whole body hyperthermia. C57BL/6J male mice were randomly assigned into control (CON) and exercise (EX) groups (n = 6 per group). EX group exercised on a programmed, motorized wheel, while CON group remained in a mouse cage in an environmental chamber at 35 degree C for ~3 hours. EX group showed a significantly higher average body core temperature (38.5 degree C +/- 0.3) compared to CON group (37.3 degree C +/- 0.3). Plasma myoglobin levels were significantly higher in EX group than in CON. Additionally, exercise significantly impaired skeletal muscle and mitochondria, as evidenced by elevated TBARS and caspase-3 levels and reduced ATP and Complex IV levels in gastrocnemius muscles in EX group. We developed a mouse model of exercise-induced mild whole body hyperthermia that recapitulates many key features of heat stress-induced skeletal muscle injury. This novel model will provide a useful tool for future investigation into the mechanisms of and intervention strategies for muscle exertional heat injury.

physiology↗
bioRxiv2026

Burn Wound Excision Drives Acute Hypermetabolism in Mice with Scald Burns

Hypermetabolism (elevated resting energy expenditure) is a hallmark of the pathophysiological response to burns. The contribution of wound excision to acute burn-induced hypermetabolism remains unclear. Importantly, while burn wound excision is a standard component of clinical burn care, it is not typically included in rodent models of burn injury. Here, we tested the hypothesis that burn wound excision drives the acute hypermetabolic response to burn trauma. C57BL/6J mice (n=12-18 per group; ~6-weeks old; 50% male) were acclimated to thermoneutral housing (30C) for 6-weeks. All mice underwent baseline body composition scans and metabolic phenotyping to determine total (TEE) and resting energy expenditure (REE). Mice were then randomized to either sham (control), scald burn (burn), wound excision (excision), or scald burn followed by immediate wound excision (burn+excision) groups. Burns and wound excisions involved ~15% of the body surface area. Mice then recovered for 14 days while individually housed in metabolic phenotyping cages. At day 14 post-injury, mice underwent a second body composition scan prior to euthanasia. There were no fatalities in the control or burn groups, whereas 23% (n=7) and 34% (n=11) of mice in the excision and burn+excision groups died or were euthanized during the 14-day recovery period. Male and female mice exhibited broadly similar responses to injury in terms of REE and TEE. Compared to control, REE was greater in burn (47%), excision (102%), and burn+excision groups (136%) during the first week post-injury (P<0.001 for all). Compared to control mice, wound excision (alone or following burns) resulted in a greater acute loss in body mass than burn injury alone. However, this cachectic response was more sustained in male mice compared to females. Similarly, wound excision (alone or following burns) resulted in greater bone mineral content and density loss compared to sham and burn alone in both sexes. Wound excision is a key contributor to the hypermetabolic and cachectic response to burn trauma in mice. We posit that rodent studies aiming to recapitulate burn-induced hypermetabolism and cachexia should include burn wound excision to better model the clinical sequelae to burns.

physiology↗