High sugar-induced repression of antioxidant and anti-apoptotic genes in lens: Reversal by pyruvate

Pyruvate alleviates high glucose-induced endoplasmic reticulum stress and apoptosis in HK-2 cells

Endoplasmic reticulum (ER) stress plays a critical role in the development of diabetic nephropathy (DN). We previously demonstrated that pyruvate (Pyr)-enriched oral rehydration solution improved glucometabolic disorders and ameliorated DN outcome in db/db mice. Here, we investigated the effects of Pyr on high glucose-induced ER stress and apoptosis in HK-2 cells. Our results suggest that high glucose can induce reactive oxygen species production, apoptosis and ER stress in HK-2 cells, and that Pyr treatment can ameliorate these effects and restore the expression of key proteins involved in ER stress. Thus, Pyr may have potential for the development of novel strategies for the prevention and treatment of clinical DN.

RSL3 induced autophagic death in glioma cells via causing glycolysis dysfunction

RSL3 is a type of small molecular compound which can inactivate glutathione peroxidase 4 (GPX4) and induce ferroptosis, but its role in glioma cell death remains unclear. In this study, we found RSL3 inhibited the viabilities of glioma cells and induced glioma cell death in a dose-dependent manner. In vitro studies revealed that RSL3-induced cell death was accompanied with the changes of autophagy-associated protein levels and was alleviated by pretreatment of 3-Methyladenine, bafilomycin A1 and knockdown of ATG5 with siRNA. The ATP and pyruvate content as well as the protein levels of HKII, PFKP, PKM2 were decreased in cells treated by RSL3, indicating that RSL3 induced glycolysis dysfunction in glioma cells. Moreover, supplement of exterior sodium pyruvate, which was a final product of glycolysis, not only inhibited the changes of autophagy-associated protein levels caused by RSL3, but also prevented RSL3-induced cell death. In vivo data suggested that the inhibitory effect of RSL3 on the growth of glioma cells was associated with glycolysis dysfunction and autophagy activation. Taken together, RSL3 induced autophagic cell death in glioma cells via causing glycolysis dysfunction.

Pyruvate in reduced osmolarity oral rehydration salt corrected lactic acidosis in sever scald rats

BACKGROUND

A novel pyruvate-based oral rehydration salt (Pyr-ORS) was demonstrated of superiority over bicarbonate- or citrate-based one to preserve organ function and correct lactic acidosis in rehydration of lethal shock in animals. This study further compared these effects between low-osmolar Pyr-ORS and equimolar citrate-based counterpart.

METHODS

Eighty rats, using a fatal burn shock model, were randomized into four groups (two subgroups per group: n = 10): the sham group (group SR), Pyr-ORS group (group PR), WHO-ORS III group (group CR), and no rehydration group. ORS was delivered by manual gavage during 24 h following burns. Oral administration consisted of half of counted volume in the initial 8 h plus the rest in the later 16 h. Systemic hemodynamics, visceral organ surface blood flow, organ function, and metabolic acidosis were determined at 8 h and 24 h after burn. Another set of rats with identical surgical procedures without tests was observed for survival.

RESULTS

Survival was markedly improved in the groups PR and CR; the former showed a higher survival rate than the latter at 24 h (40% versus 20%, P < 0.05). Systemic hemodynamics, visceral blood flow, and function of heart, liver, and kidney were greatly restored in group PR, compared with group CR (all P < 0.05). Hypoxic lactic acidosis was efficiently reversed in group PR, instead of group CR, (pH 7.36 versus 7.11, base excess 2.1 versus -9.1 mmol/L, lactate 4.28 versus 8.18 mmol/L; all P < 0.05) at 24 h after injury.

CONCLUSIONS

Pyruvate was advantageous over citrate in low-osmolar ORS for protection of organs and survival; pyruvate, but not citrate, in the ORS corrected hypoxic lactic acidosis in rats subjected to lethal burn shock in 24 h.

Phospho-transfer networks and ATP homeostasis in response to an ineffective electron transport chain in Pseudomonas fluorescens

Although oxidative stress is known to impede the tricarboxylic acid (TCA) cycle and oxidative phosphorylation, the nutritionally-versatile microbe, Pseudomonas fluorescens has been shown to proliferate in the presence of hydrogen peroxide (H2O2) and nitrosative stress. In this study we demonstrate the phospho-transfer system that enables this organism to generate ATP was similar irrespective of the carbon source utilized. Despite the diminished activities of enzymes involved in the TCA cycle and in the electron transport chain (ETC), the ATP levels did not appear to be significantly affected in the stressed cells. Phospho-transfer networks mediated by acetate kinase (ACK), adenylate kinase (AK), and nucleoside diphosphate kinase (NDPK) are involved in maintaining ATP homeostasis in the oxidatively-challenged cells. This phospho-relay machinery orchestrated by substrate-level phosphorylation is aided by the up-regulation in the activities of such enzymes like phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPDK), and phosphoenolpyruvate synthase (PEPS). The enhanced production of phosphoenolpyruvate (PEP) and pyruvate further fuel the synthesis of ATP. Taken together, this metabolic reconfiguration enables the organism to fulfill its ATP need in an O2-independent manner by utilizing an intricate phospho-wire module aimed at maximizing the energy potential of PEP with the participation of AMP.

Effect of coffee (caffeine) against human cataract blindness

Previous biochemical and morphological studies with animal experiments have demonstrated that caffeine given topically or orally to certain experimental animal models has significant inhibitory effect on cataract formation. The present studies were undertaken to examine if there is a correlation between coffee drinking and incidence of cataract blindness in human beings. That has been found to be the case. Incidence of cataract blindness was found to be significantly lower in groups consuming higher amounts of coffee in comparison to the groups with lower coffee intake. Mechanistically, the caffeine effect could be multifactorial, involving its antioxidant as well as its bioenergetic effects on the lens.