Biology subjects

Ebenebe, O. V.

Publications and source records attributed to Ebenebe, O. V..

4 recordsLinked to original sources

bioRxiv2026

Formate reduces ischemic injury in the male heart by increasing protein S-nitrosation

Ischemic heart disease is a leading cause of death for both men and women in the United States. We and others have demonstrated that nitric oxide (NO) signaling and associated protein S-nitrosation (SNO) play a key role in reducing ischemic injury in the heart. We also find that while females typically exhibit endogenous protection from ischemic injury, this protection is abrogated with the loss of the formate-generating enzyme alcohol dehydrogenase 5 (ADH5), but formate supplementation provided a rescue. Here, we investigate the cardioprotective efficacy of formate in male hearts. Hearts were Langendorff-perfused and subjected to ischemia/reperfusion (I/R) injury with and without formate. Formate-mediated protection was also examined using an in vitro model of coverslip-induced ischemic injury to identify molecular underpinnings. We found that formate yields protection from I/R injury in ex vivo and in vitro models by increasing post-ischemic protein SNO levels, while NO synthase inhibition blocked this formate-mediated increase in protein SNO in vitro, and attenuated protection from I/R injury ex vivo. Moreover, post-ischemic levels of tetrahydrobiopterin (BH4), a cofactor necessary for NOS function, were preserved in formate-treated hearts. Furthermore, inhibition of dihydrofolate reductase (DHFR), a one-carbon enzyme critical for BH4 recycling, blunted formate-mediated protection ex vivo. Collectively, our findings suggest that formate is a potent cardioprotective agent that confers protection by preserving post-ischemic BH4 levels, and enhancing protein SNO levels through a NOS-dependent mechanism. These findings have significant implications for the clinical prevention and treatment of ischemic heart disease in males.

physiology↗

bioRxiv2025

GSNOR deletion differentially alters age-related cardiac function in a sex-dependent manner.

S-nitrosoglutathione reductase (GSNOR), a regulator of protein S-nitrosylation (SNO), has been proposed as a longevity protein. GSNOR signaling has been implicated in both the alleviation and exacerbation of aging. In the context of ischemia reperfusion injury, we previously showed a sex-dependent response to GSNOR inhibition; cardiac damage was alleviated in males and exacerbated in females. Considering sex differences in the incidence of cardiovascular disease with age, we investigated the effect of GSNOR deletion (-/-) on age-related changes in cardiac function. We performed longitudinal 2D-echocardiography measurements in M-Mode on male and female, wildtype (WT) and GSNOR-/- mice at young (3-4 months), middle (13-15 months) and old age (18-20 months). Left ventricular wall thickness and ejection fraction decreased with age in WT mice but was maintained in GSNOR-/-. Western blot and GSNOR-activity assay showed GSNOR activity and expression decreased with age in WT females alone. Isolated cardiomyocyte force-coupling analysis showed increasing age was inversely correlated with sarcomere shortening and Ca2+ release kinetics in WT males, but not GSNOR-/-. WT females showed slower Ca2+ re-uptake after contraction and time to peak sarcomere shortening, but all other parameters were maintained. GSNOR-/- females exhibited slower Ca2+ re-uptake and decreased sarcomere shortening. Proteomic analysis of SNO from females showed upregulation of Pyruvate Dehydrogenase, E1 Beta and Dihydrolipoamide dehydrogenase in young WT females relative to middle-age mice. Together our data suggest that GSNOR deletion is cardioprotective by maintaining cardiac function in males; while in females the absence of GSNOR removes an age-essential SNO-imbalance, which may exacerbate pathologies.

physiology↗

bioRxiv2023

Prenatal Arsenite Exposure Alters Maternal Cardiac Remodeling During Late Pregnancy

Exposure to inorganic arsenic through drinking water is widespread and has been linked to many chronic diseases, including cardiovascular disease. Arsenic exposure has been shown to alter hypertrophic signaling in the adult heart, as well as in-utero offspring development. However, the effect of arsenic on maternal cardiac remodeling during pregnancy has not been studied. As such, there is a need to understand how environmental exposure contributes to adverse pregnancy-related cardiovascular events. This study seeks to understand the impact of trivalent inorganic arsenic exposure during gestation on maternal cardiac remodeling in late pregnancy, as well as offspring outcomes. C57BL/6J mice were exposed to 0 (control), 100 or 1000 {micro}g/L sodium arsenite (NaAsO2) beginning at embryonic day (E) 2.5 and continuing through E17.5. Maternal heart function and size were assessed via transthoracic echocardiography, gravimetric measurement, and histology. Transcript levels of hypertrophic markers were probed via qRT-PCR and confirmed by western blot. Offspring outcomes were assessed through echocardiography and gravimetric measurement. We found that exposure to 1000 {micro}g/L iAs abrogated normal physiologic growth of the maternal heart during late pregnancy and reduced transcript levels of estrogen receptor alpha (ER), progesterone receptor membrane component 1 (Pgrmc1) and progesterone receptor membrane component 2 (Pgrmc2). Both 100 and 1000 {micro}g/L iAs also reduced transcription of protein kinase B (Akt) and atrial natriuretic peptide (ANP). Akt protein expression was also significantly reduced after 1000 {micro}g/L iAs exposure in the maternal heart with no change in activating phosphorylation. This significant abrogation of maternal cardiac hypertrophy suggests that arsenic exposure during pregnancy can potentially contribute to cardiovascular disease. Taken together, our findings further underscore the importance of reducing arsenic exposure during pregnancy and indicate that more research is needed to assess the impact of arsenic and other environmental exposures on the maternal heart and adverse pregnancy events.

pharmacology and toxicology↗

bioRxiv2023

Nitric Oxide modulates spontaneous Ca2+ release and ventricular arrhythmias during β adrenergic signalling through S-nitrosylation of Calcium/Calmodulin dependent kinase II

RationaleNitric oxide (NO) has been identified as a signalling molecule generated during {beta}-adrenergic receptor (AR) stimulation in the heart. Furthermore, a role for NO in triggering spontaneous Ca2+ release via S-nitrosylation of Ca2+/calmodulin kinase II delta (CaMKII{delta}) is emerging. NO donors are routinely used clinically for their cardioprotective effects in the heart, but it is unknown how NO donors modulate the pro-arrhythmic CaMKII to alter cardiac arrhythmia incidence. ObjectiveWe test the role of S-nitrosylation of CaMKII{delta} at the Cys-273 inhibitory site and Cys-290 activating site in cardiac Ca2+ handling and arrhythmogenesis before and during {beta}-AR stimulation. Methods and ResultsWe measured Ca2+-handling in isolated cardiomyocytes from C57BL/6J wild-type (WT) mice and mice lacking CaMKII{delta} expression (CaMKII{delta}-KO) or with deletion of the S-nitrosylation site on CaMKII{delta} at Cys-273 or Cys-290 (CaMKII{delta}-C273S and -C290A knock-in mice). Cardiomyocytes were exposed to NO donors, S-nitrosoglutathione (GSNO; 150 M), sodium nitroprusside (SNP; 200 M) and/or {beta}-adrenergic agonist isoproterenol (ISO; 100 nM). WT and CaMKII{delta}-KO cardiomyocytes treated with GSNO showed no change in Ca2+ transient or spark properties under baseline conditions (0.5 Hz stimulation frequency). Both WT and CaMKII{delta}-KO cardiomyocytes responded to ISO with a full inotropic and lusitropic Ca2+ transient response as well as increased Ca2+ spark frequency. However, the increase in Ca2+ spark frequency was significantly attenuated in CaMKII{delta}-KO cardiomyocytes. The protection from ISO-induced Ca2+ sparks and waves was mimicked by GSNO pre-treatment in WT cardiomyocytes, but lost in CaMKII{delta}-C273S cardiomyocytes that displayed a robust increase in Ca2+ waves. This observation is consistent with CaMKII{delta}-C273 S-nitrosylation being critical in limiting ISO-induced arrhythmogenic sarcoplasmic reticulum Ca2+ leak. When GSNO was applied after ISO this protection was not observed in WT or CaMKII{delta}-C273S but was apparent in CaMKII{delta}-C290A. In Langendorff-perfused isolated hearts, GSNO pre-treatment limited ISO-induced arrhythmias in WT but not CaMKII{delta}-C273S hearts, while GSNO exposure after ISO sustained or exacerbated arrhythmic events. ConclusionsWe conclude that prior S-nitrosylation of CaMKII{delta} at Cys-273 can limit subsequent {beta}-AR induced arrhythmias, but that S-nitrosylation at Cys-290 might worsen or sustain {beta}-AR-induced arrhythmias. This has important implications for the administration of NO donors in the clinical setting.

physiology↗