Mild caloric restriction up-regulates the expression of prohibitin: a proteome study.

Caloric restriction (CR) is well known to expand lifespan in a variety of species and to retard many age-related diseases. The effects of relatively mild CR on the proteome profile in relation to lifespan have not yet been reported, despite the more extensive studies of the stricter CR conditions. Thus, the present study was conducted to elucidate the protein profiles in rat livers after mild CR for a relatively short time. Young growing rats were fed CR diets (10% and 30% CR) for 1month. We performed the differential proteomic analysis of the rat livers using two-dimensional electrophoresis combined with MALDI-TOF mass spectrometry. The most remarkable protein among the differentially expressed proteins was found to be prohibitin, the abundance of which was increased by 30% CR. Prohibitin is a ubiquitously expressed protein shown to suppress cell proliferation and to be related to longevity. The increase in prohibitin was observed both in 10% and 30% CR by Western blot analysis. Furthermore, induction of AMP-activated kinase (AMPK) protein, related to the actions of prohibitin in promoting longevity, was observed. The increased prohibitin level in response to subtle CR suggests that this increase may be one of the early events leading to the expansion of lifespan in response to CR.

Effect of mild restriction of food intake on gene expression profile in the liver of young rats: reference data for in vivo nutrigenomics study.

Recent transcriptomics studies on the effect of long-term or severe energy restriction (ER) have revealed that many genes are dynamically modulated by this condition in rodents. The present study was conducted to define the global gene expression profile in response to mild ER treatment. Growing rats were fed with reduced amount of diet (5-30 % ER) for 1 week or 1 month. Using DNA microarray analysis of the liver, seventy-two genes that were consistently changed through the different ER levels were identified. Many were related to lipid metabolism including genes encoding key enzymes such as carnitine palmitoyltransferase 1 and fatty acid synthase. Interestingly, a number of genes were altered even by 5 % ER for 1 week where no differences in weight gain were observed. The information obtained in the present study can be used as a valuable reference data source in the transcriptomics studies of food and nutrition in which subtle differences in food intake sometimes hinder appropriate interpretation of the data.

Altered gene expression profiles and higher frequency of spontaneous DNA strand breaks in APEX2-null thymus.

A second class II AP endonuclease, APEX2, possesses strong 3'-5' exonuclease and 3'-phosphodiesterase activities but only very weak AP-endonuclease activity. APEX2 associates with proliferating cell nuclear antigen (PCNA), and the progression of S phase of the cell cycle is accompanied by its expression. APEX2-null mice exhibit severe dyslymphopoiesis in thymus as well as moderate dyshematopoiesis and growth retardation. Comparative gene expression profiling of wild-type and APEX2-null mice using an oligonucleotide microarray revealed that APEX2-null thymus has significantly altered gene expression profiles, reflecting its altered populations of thymocytes. Beyond these altered populations, APEX2-null thymus exhibits significant alterations in expression of genes involved in DNA replication, recombination and repair, including Apex1, Exo1 and Fen1 as well as master genes for the DNA damage response, such as E2f1, Chek1, and proapoptotic genes. We therefore examined the extent of DNA strand breakage, and found that both of single-strand breaks detected as comets and double-strand breaks detected as gammaH2AX foci were significantly higher in frequency in most APEX2-null thymocytes compared to wild-type thymocytes. This higher frequency of DNA breaks was accompanied by increased expression of PCNA and increased phosphorylation of p53 at Ser23 and to a lesser extent, at Ser18. The present study clearly demonstrates that APEX2-null lymphocytes have a higher frequency of DNA breaks, indicating that APEX2 may play an important role(s) during their generation and/or repair.

Absorption of dietary cholesterol oxidation products and their downstream metabolic effects are reduced by dietary apple polyphenols.

Exogenous and endogenous cholesterol oxidation products (COPs) perturb various metabolic processes, and thereby they may induce various homeostasis-related disorders. Here, we observed that procyanidin-rich dietary apple polyphenol (APP) from unripe apples alleviates the perturbation of lipid metabolism by decreasing the exogenous COP levels in rats. Dietary COPs may be the greatest source of COPs found in the human body. Rats (4 weeks of age) were fed AIN-purified diets containing 0.3% COPs supplemented with 0.5 or 2.5% APP for 3 weeks. Dietary APP alleviated the growth inhibition action of the exogenous COPs. The modulations of the liver lipid profile by COPs remained unchanged. However, serum total cholesterol, high-density lipoprotein cholesterol, and triglyceride levels increased following the intake of dietary APP. Further, dietary APP inhibited the increase in lipid peroxide levels in the liver and serum by COPs. The activity of hepatic Delta6 desaturase was lowered by dietary APP in a dose-dependent manner, although exogenous COPs generally increased the activity of this enzyme. In keeping with this observation, Delta6 desaturation indices in the phospholipids and cholesteryl esters of the liver and serum lipids were lower in the APP-fed groups than those in the control group. Dietary APP also promoted the excretion of exogenous COPs, cholesterol, and acidic steroids in feces. Therefore, the inhibition of intestinal absorption of COPs may partly contribute to the alleviation of the perturbation of lipid metabolism and lipid peroxidation levels. Thus, APP may be an important removal agent of exogenous toxic material such as COPs contained in processed or fast foods.

Dose-dependent hypocholesterolemic actions of dietary apple polyphenol in rats fed cholesterol.

The dose-dependent hypocholesterolemic and antiatherogenic effects of dietary apple polyphenol (AP) from unripe apple, which contains approximately 85% catechin oligomers (procyanidins), were examined in male Sprague-Dawley rats (4 wk of age) given a purified diet containing 0.5% cholesterol. Dietary AP at 0.5 and 1.0% levels significantly decreased the liver cholesterol level compared with that in the control (AP-free diet-fed) group. Dietary AP also significantly lowered the serum cholesterol level compared with that in the control group. However, the HDL cholesterol level was significantly higher in the 1.0% AP-fed group than in the control group. Accordingly, the ratio of HDL-cholesterol/total cholesterol was significantly higher in the 0.5% AP-fed group and 1.0% AP-fed group than in the control group. Moreover, the atherogenic indices in the 0.5 and 1.0% AP-fed groups were significantly lower than those in the control group. The activity of hepatic cholesterol 7alpha-hydroxylase tended to be increased by dietary AP in a dose-dependent manner. In accord with this observation, dietary AP increased the excretion of acidic steroids in feces. Dietary AP also significantly promoted the fecal excretion of neutral steroids in a dose-dependent manner. These observations suggest that dietary AP at a 0.5 or 1.0% level exerts hypocholesterolemic and antiatherogenic effects through the promotion of cholesterol catabolism and inhibition of intestinal absorption of cholesterol.

Oxidative stress causes heart failure with impaired mitochondrial respiration.

Elderly people insidiously manifest the symptoms of heart failure, such as dyspnea and/or physical disabilities in an age-dependent manner. Although previous studies suggested that oxidative stress plays a pathological role in the development of heart failure, no direct evidence has been documented so far. In order to investigate the pathological significance of oxidative stress in the heart, we generated heart/muscle-specific manganese superoxide dismutase-deficient mice. The mutant mice developed progressive congestive heart failure with specific molecular defects in mitochondrial respiration. In this paper, we showed for the first time that the oxidative stress caused specific morphological changes of mitochondria, excess formation of superoxide (O(2)(*)(-)), reduction of ATP, and transcriptional alterations of genes associated with heart failure in respect to cardiac contractility. Accordingly, administration of a superoxide dismutase mimetic significantly ameliorated the symptoms. These results implied that O(2)(*)(-) generated in mitochondria played a pivotal role in the development and progression of heart failure. We here present a bona fide model for human cardiac failure with oxidative stress valuable for therapeutic interventions.

Inhibition of osteoporosis induced by protein deficient (PD) food intake by active vitamin D(3) and vitamin K(2) in rats.

Independent use of K(2) and D(3) and simultaneous application of K(2) and D(3) inhibited the development of osteoporosis caused by PD food intake. The ALP activity of urine as a marker of bone formation osteoporosis did not rise in rats fed PD foods containing D(3), K(2) or both together. Body and womb weights fell in rats fed PD foods with D(3) K(2) and both D(3), K(2). Osteoporosis caused by PD food intake found to be very similar to type II osteoporosis in respects of inhibition by D(3) and K(2) and rising urinary ALP activity.

Inhibition of osteoporosis in rats fed with sugar cane wax.

Rats fed on a restricted, semi-purified diet containing a 50%-reduced level of carbohydrate and oil, but normal levels of protein, minerals and vitamins, exhibited osteoporosis. However, rats fed on this restricted diet, but containing sugar cane wax, did not exhibit this bone disease. Sugar cane wax, containing a long-chain carbohydrate with an OH radical, prevented the development of osteoporosis via a non-estrogenic mechanism.

Running inhibits osteoporosis induced by protein-deficient (PD) food intake.

Running at 0.7 km/h for 10 min every day inhibited development of osteoporosis caused by protein deficient (PD) food intake. Urine alkaline phosphatase (ALP), a marker of bone formation osteoporosis, was not elevated in rats fed PD, when the osteoporosis was inhibited by running. Estrogen supplementation increased bone-breaking energy (BBE), but did not increase bone mineral density (BMD), and did not decrease urinary ALP levels.

Inhibition of osteoporosis due to restricted food intake by the fish oils DHA and EPA and perilla oil in the rat.

Seven-week old female rats fed restricted foods including the fish oils Docosahesaenoic Acid (DHA) and Eicosapentaenoic Acid (EPA) and perilla oil with food intake decreased by 50%, had increases of fracture force and bone mineral density (BMD) and decreases in levels of Deoxypiridinoline (Dpd) and Calcium (Ca) in the urine, compared with those of rats with osteoporosis due to restricted soy bean oil food intake. Therefore, the fish oils DHA and EPA and perilla oil depressed excretion of urinary Ca and inhibited osteoporosis due to restricted food intake.