Caloric restriction primes mitochondria for ischemic stress by deacetylating specific mitochondrial proteins of the electron transport chain.

RATIONALE: Caloric restriction (CR) confers cardioprotection against ischemia/reperfusion injury. However, the exact mechanism(s) underlying CR-induced cardioprotection remain(s) unknown. Recent evidence indicates that Sirtuins, NAD(+)-dependent deacetylases, regulate various favorable aspects of the CR response. Thus, we hypothesized that deacetylation of specific mitochondrial proteins during CR preserves mitochondrial function and attenuates production of reactive oxygen species during ischemia/reperfusion. OBJECTIVE: The objectives of the present study were (1) to investigate the effect of CR on mitochondrial function and mitochondrial proteome and (2) to investigate what molecular mechanisms mediate CR-induced cardioprotection. METHODS AND RESULTS: Male 26-week-old Fischer344 rats were randomly divided into ad libitum-fed and CR (40% reduction) groups for 6 months. No change was observed in basal mitochondrial function, but CR preserved postischemic mitochondrial respiration and attenuated postischemic mitochondrial H(2)O(2) production. CR decreased the level of acetylated mitochondrial proteins that were associated with enhanced Sirtuin activity in the mitochondrial fraction. We confirmed a significant decrease in the acetylated forms of NDUFS1 and cytochrome bc1 complex Rieske subunit in the CR heart. Low-dose resveratrol treatment mimicked the effect of CR on deacetylating them and attenuated reactive oxygen species production during anoxia/reoxygenation in cultured cardiomyocytes without changing the expression levels of manganese superoxide dismutase. Treatment with nicotinamide completely abrogated the effect of low-dose resveratrol. CONCLUSIONS: These results strongly suggest that CR primes mitochondria for stress resistance by deacetylating specific mitochondrial proteins of the electron transport chain. Targeted deacetylation of NDUFS1 and/or Rieske subunit might have potential as a novel therapeutic approach for cardioprotection against ischemia/reperfusion.

Molecular hydrogen alleviates nephrotoxicity induced by an anti-cancer drug cisplatin without compromising anti-tumor activity in mice.

PURPOSE: Cisplatin is a widely used anti-cancer drug in the treatment of a wide range of tumors; however, its application is limited by nephrotoxicity, which is affected by oxidative stress. We have reported that molecular hydrogen (H(2)) acts as an efficient antioxidant (Ohsawa et al. in Nat Med 13:688-694, 2007). Here we show that hydrogen efficiently mitigates the side effects of cisplatin by reducing oxidative stress. METHODS: Mice were administered cisplatin followed by inhaling hydrogen gas (1% H(2) in air). Furthermore, instead of inhaling hydrogen gas, we examined whether drinking water containing hydrogen (hydrogen water; 0.8 mM H(2) in water) is applicable by examining oxidative stress, mortality, and body-weight loss. Nephrotoxicity was assessed by morphological changes, serum creatinine and blood urea nitrogen (BUN) levels. RESULTS: Inhalation of hydrogen gas improved mortality and body-weight loss caused by cisplatin, and alleviated nephrotoxicity. Hydrogen was detected in blood when hydrogen water was placed in the stomach of a rat. Consuming hydrogen water ad libitum also reduced oxidative stress, mortality, and body-weight loss induced by cisplatin in mice. Hydrogen water improved metamorphosis accompanying decreased apoptosis in the kidney, and nephrotoxicity as assessed by serum creatinine and BUN levels. Despite its protective effects against cisplatin-induced toxicity, hydrogen did not impair anti-tumor activity of cisplatin against cancer cell lines in vitro and tumor-bearing mice in vivo. CONCLUSION: Hydrogen has potential for improving the quality of life of patients during chemotherapy by efficiently mitigating the side effects of cisplatin.

Consumption of molecular hydrogen prevents the stress-induced impairments in hippocampus-dependent learning tasks during chronic physical restraint in mice.

We have reported that hydrogen (H(2)) acts as an efficient antioxidant by gaseous rapid diffusion. When water saturated with hydrogen (hydrogen water) was placed into the stomach of a rat, hydrogen was detected at several microM level in blood. Because hydrogen gas is unsuitable for continuous consumption, we investigated using mice whether drinking hydrogen water ad libitum, instead of inhaling hydrogen gas, prevents cognitive impairment by reducing oxidative stress. Chronic physical restraint stress to mice enhanced levels of oxidative stress markers, malondialdehyde and 4-hydroxy-2-nonenal, in the brain, and impaired learning and memory, as judged by three different methods: passive avoidance learning, object recognition task, and the Morris water maze. Consumption of hydrogen water ad libitum throughout the whole period suppressed the increase in the oxidative stress markers and prevented cognitive impairment, as judged by all three methods, whereas hydrogen water did not improve cognitive ability when no stress was provided. Neural proliferation in the dentate gyrus of the hippocampus was suppressed by restraint stress, as observed by 5-bromo-2'-deoxyuridine incorporation and Ki-67 immunostaining, proliferation markers. The consumption of hydrogen water ameliorated the reduced proliferation although the mechanistic link between the hydrogen-dependent changes in neurogenesis and cognitive impairments remains unclear. Thus, continuous consumption of hydrogen water reduces oxidative stress in the brain, and prevents the stress-induced decline in learning and memory caused by chronic physical restraint. Hydrogen water may be applicable for preventive use in cognitive or other neuronal disorders.

Prevention of chemotherapy-induced alopecia by the anti-death FNK protein.

Many anticancer drugs attack rapidly dividing cells, including not only malignant cells but also hair follicle cells, and induce alopecia. Chemotherapy-induced alopecia (CIA) is an emotionally distressing side effect of cancer chemotherapy. There is currently no useful preventive therapy for CIA. We have previously constructed anti-death rFNK protein from rat Bcl-x(L) by site-directed mutagenesis to strengthen cytoprotective activity. When fused to the protein transduction domain (PTD) of HIV/Tat, the fusion protein PTD (TAT)-rFNK successfully entered cells from the outside in vitro and in vivo to exhibit anti-death activity against apoptosis and necrosis. Here, we show that topical application of FNK protected against CIA in a newborn rat model. The protective activity against hair-loss was observed in 30-1000 nM TAT-rFNK administrative groups in a dose-dependent manner. Furthermore, a human version of FNK (hFNK) fused to other PTD peptides exhibited a protective ability. These results suggest that PTD-FNK possesses protective activity against CIA and is not restricted to a sequence of PTD peptides or species of FNK. Thus, PTD-FNK represents potential to develop a useful method for preventing CIA in cancer patients.

Compensatory change of interacting amino acids in the coevolution of transcriptional coactivator MBF1 and TATA-box-binding protein.

To elucidate the transcriptional regulation in eukaryotic genome network, it is important to understand coevolution of transcription factors, transcriptional coactivators, and TATA-box-binding protein (TBP). In this study, coevolution of transcriptional coactivator multiprotein-bridging factor 1 and its interacting target TBP was first evaluated experimentally by examining if compensatory amino acid changes took place at interacting sites of both proteins. The experiments were conducted by identifying interaction sites and comparing the amino acids at these sites among different organisms. Here, we provide evidence for compensatory changes of transcription coactivator and its interacting target, presenting the 1st report that transcription coactivator may have undergone coevolution with TBP.

MIDAS/GPP34, a nuclear gene product, regulates total mitochondrial mass in response to mitochondrial dysfunction.

To investigate the regulatory system in mitochondrial biogenesis involving crosstalk between the mitochondria and nucleus, we found a factor named MIDAS (mitochondrial DNA absence sensitive factor) whose expression was enhanced by the absence of mitochondrial DNA (mtDNA). In patients with mitochondrial diseases, MIDAS expression was increased only in dysfunctional muscle fibers. A majority of MIDAS localized to mitochondria with a small fraction in the Golgi apparatus in HeLa cells. To investigate the function of MIDAS, we stably transfected HeLa cells with an expression vector carrying MIDAS cDNA or siRNA. Cells expressing the MIDAS protein and the siRNA constitutively showed an increase and decrease in the total mass of mitochondria, respectively, accompanying the regulation of a mitochondria-specific phospholipid, cardiolipin. In contrast, amounts of the mitochondrial DNA, RNA and proteins did not depend upon MIDAS. Thus, MIDAS is involved in the regulation of mitochondrial lipids, leading to increases of total mitochondrial mass in response to mitochondrial dysfunction.