Biomedical subjects

Hideko Nakamoto

Publications and source records attributed to Hideko Nakamoto.

10 recordsLinked to original sources

PubMed2006

Defining the mitochondrial proteomes from five rat organs in a physiologically significant context using 2D blue-native/SDS-PAGE.

In accordance with their manifold tasks, various dysfunctions of mitochondria are critically involved in a large number of diseases and the aging process. This has inspired considerable efforts to identify all the mitochondrial proteins by denaturing approaches, notably, the standard gel-based method employing isoelectric focusing. Because a significant part of the mitochondrial proteome is membrane-associated and/or functions as homo- or heterooligomeric protein complexes, there is an urgent need to detect and identify mitochondrial proteins, both membranous and soluble ones, under conditions preserving protein-protein interactions. Here, we investigated mitochondria of five different rat organs (kidney, liver, heart, skeletal muscle, and brain) solubilized with digitonin, enabling the quantitative extraction of the five oxidative phosphorylation (OXPHOS) complexes. The analysis by blue-native (BN)-PAGE recovered the OXPHOS complexes to a large extent as supercomplexes and separated many other protein complexes and individual proteins which were resolved by subsequent 2D SDS-PAGE revealing the tissue-diverse mitochondrial proteomes. Using MS peptide mass fingerprinting, we identified in all five organs 92 nonredundant soluble and membrane-embedded non-OXPHOS proteins, among them, many as constituents of known mitochondrial protein complexes as well as novel ones such as the putative "stomatin-like protein 2 complex" with an apparent mass of ca. 1800 kDa. Interestingly, the identification list included 36 proteins known or presumed to be localized to nonmitochondrial compartments, for example, glycolytic enzymes, clathrin heavy chain, valosin-containing protein/p97, VoV1-ATPase, and Na,K-ATPase. We expect that more than 200 distinct non-OXPHOS proteins of digitonin-solubilized rat mitochondria separated by 2D BN/SDS-PAGE, representing a partial "protein interactome" map, can be identified.

Animals↗

PubMed2005

Carbonyl modification in rat liver histones: decrease with age and increase by dietary restriction.

We studied carbonylation, a form of oxidative modification of proteins, of histones in rat livers. Histones H1, H2B/H2A, and H3 were significantly carbonylated but the modification was almost undetectable in H4. Contrary to the generally accepted view of increased protein carbonylation with age, the modification of histones was significantly lower in old (30-month-old) than in young (5-month-old) animals. Dietary restriction of older animals for 2 months resulted in increase in carbonylation comparable to that at the young level. These findings may have physiological implications in chromatin structure/function in aging and beneficial effects of DR by influencing transcription, replication, and/or repair activities.

Aging↗

PubMed2005

Lung cancer in smoking patients inversely alters the activity of hOGG1 and hNTH1.

N-Glycosylases excise the damaged adducts from DNA. 7,8-Dihydro-8-oxoguanine in human cells is repaired by OGG1 and hNTH1. The activities of hOGG1 and hNTH1 were measured, using modified and 32P labelled oligonucleotides, in bronchial biopsy samples of smoking patients with non-small cell lung carcinoma. The activity of hOOG1 was significantly higher in biopsies from tumour tissues compared with intra-individual control samples. On the contrary, the activity of endonuclease III homologue, hNTH1, was lower in tumours compared to controls. These opposing alterations in DNA repair enzymes may affect cancer growth due to the increased formation of AP sites.

Aged↗

PubMed2005

The effects of moderate, strenuous, and overtraining on oxidative stress markers and DNA repair in rat liver.

Physical exercise above a certain load has been suggested as being a cause of oxidative stress. We have tested whether training with moderate (MT), strenuous (ST), or over (OT) load can cause alterations in the activities of antioxidant enzymes, lipid peroxidation, protein oxidation, DNA damage, or activity of 8-oxoG-DNA glycosylase (OGG1) in rat liver. The levels of corticosterone decreased in all exercising groups but the differences were not significant. Adrenocorticotrophin hormone (ACTH) levels decreased, not significantly, in MT and OT compared to C. Activity levels of antioxidant enzymes did not change significantly in the liver. The levels of reactive carbonyl derivative (RCD) content decreased in the liver of exercising animals, and the differences reached significance between control and moderately trained groups. The changes in the levels of lipid peroxidation (LIPOX) were not significant, but were lower in the exercised groups. The 8-hydroxydeoxyguanosine (8-OHdG) levels increased in the OT group, and the activity of OGG1 measured from crude cell extracts tended to increase in MT and ST. The findings of this study imply that overtraining induces oxidative damage to nuclear DNA, but not to liver lipids and proteins.

Adrenocorticotropic Hormone↗

PubMed2004

Regular exercise: an effective means to reduce oxidative stress in old rats.

A healthy diet and regular exercise are among the major factors that influence quality of life (QOL) in old age. Exercise is believed to be beneficial to improve QOL, retarding age-related decline of physiological functions and preventing age-related diseases. Regular physical exercise can possibly improve age-related functional decline and delay onset of age-related diseases by attenuating potentially harmful oxidative damage and suppressing inflammatory processes even in older age.

Aging↗

PubMed2003

Marathon running alters the DNA base excision repair in human skeletal muscle.

Reactive oxygen and nitrogen species generated either as products of aerobic metabolism or as a consequence of environmental mutagens, oxidatively modify DNA. Formamidopyrimidine-DNA glycosylase (Fpg) and endonuclease III (endo III) or their functional mammalian homologues repair 7,8-dihydro-8-oxoguanine (8-oxoG) and damaged pyrimidines, respectively, to curb the deleterious effects of oxidative DNA alterations. A single bout of physical exercise can induce oxidative DNA damage. However, its effect on the activity of repair enzymes is not known. Here we report that the activity of a functional homolog of Fpg, human 8-oxoG DNA glycosylase (hOGG1), is increased significantly, as measured by the excision of 32P labeled damaged oligonucleotide, in human skeletal muscle after a marathon race. The AP site repair enzyme did not change significantly. Despite the large individual differences among the six subjects measured, data suggest that a single-bout of aerobic exercise increases the activity of hOGG1 which is responsible for the excision of 8-oxoG. The up-regulation of DNA repair enzymes might be an important part of the regular exercise induced adaptation process.

Biopsy↗

PubMed2002

Exercise training decreases DNA damage and increases DNA repair and resistance against oxidative stress of proteins in aged rat skeletal muscle.

Regular physical exercise retards a number of age-associated disorders, in spite of the paradox that free radical generation is significantly enhanced with exercise. Eight weeks of treadmill running resulted in nearly a 40% increase in maximal oxygen uptake in both middle-aged (20-month-old) and aged (30-month-old) rats. The age-associated increase in 8-hydroxy-2'-deoxyguanosine (8-OHdG) content was significantly attenuated in gastrocnemius muscle by exercise. The 8-OHdG repair, as measured by the excision of 32P-labeled damaged oligonucleotide, increased in muscle of exercising animals. The reactive carbonyl derivatives (RCD) of proteins did not increase with aging. However, when the muscle homogenate was exposed to a mixture of 1 mM iron sulfate and 50 mM ascorbic acid, the muscle of old control animals accumulated more RCD than that of the trained or adult groups. The chymotrypsin-like activity of proteasome complex increased in muscle of old trained rats. We suggest that regular exercise-induced adaptation attenuates the age-associated increase in 8-OHdG levels, and increases the activity of DNA repair and resistance against oxidative stress in proteins.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2002

Effect of aging and late onset dietary restriction on antioxidant enzymes and proteasome activities, and protein carbonylation of rat skeletal muscle and tendon.

Many studies have shown that lifelong dietary restriction (DR) can retard aging processes. Very few reports, however, are found that examined the effect of late onset DR on biochemical parameters in aging animals [Goto, S., Takahashi, R., Araki, S., Nakamoto, H., 2002b. Dietary restriction initiated in late adulthood can reverse age-related alterations of protein and protein metabolism. Ann. NY Acad. Sci. 959, 50-56]. We studied the effect of every-other-day feeding, initiated at the age of 26.5 months and continued for 3.5 months, on antioxidant enzymes, protein carbonyls, and proteasomes of the gastrocnemius muscle and tendon in rats. Age-related increase in the activity and content of Cu, Zn-SOD and the content of Mn-SOD was attenuated by the DR in both tissues. The same was true for glutathione peroxidase and catalase activities. Significant increase with age in protein reactive carbonyl derivatives (RCD) in the tendon was noted that was partially reversed by the DR. No significant change of RCD, however, was observed in the skeletal muscle. The age-related and DR-induced changes of the RCD in the tendon appeared to be associated with proteasome activity that decreases with age and increases by the DR. It is suggested that the late onset DR can have beneficial effects on the locomotive functions by reducing age-associated potentially detrimental oxidative protein damage in the tendon.

Achilles Tendon↗

PubMed2002

Attenuation of the development of murine solid leukemia tumor by physical exercise.

The active involvement of physical exercise in the evolution of a variety of cancers is well documented. However, its role in solid leukemia tumor development is essentially unknown. Solid leukemia tumor cells were transplanted into 21 hybrid BDF1 control mice, exercise-trained mice that did not exercise during leukemia and exercise-trained mice that exercised during leukemia. The tumor size of the continuously exercising group was ~50% of that of control and exercise-terminated animals 18 days after the transplantation. The activity of antioxidant enzymes and the levels of lipid peroxidation and 8-hydroxy-2'-deoxyguanosine were not different in the tumors of the three groups. The level of carbonylated proteins was smaller in tumors of continuously exercising animals. The mutant form of cell regulatory protein p53 and vascular endothelial growth factor were present in similar amounts in the tumor cells of each group. On the other hand, the protooncogene Ras and I-kappaB proteins were present in higher concentrations in tumors of continuously exercising rats. The present data suggest that exercise during leukemia attenuates the development of tumors in mice. The selective alteration of regulatory proteins might play a role in the beneficial effects of exercise during leukemia.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2002

Dietary restriction initiated in late adulthood can reverse age-related alterations of protein and protein metabolism.

Many reports have been published on the effects of lifelong dietary restriction (DR) on a variety of parameters such as life span, carcinogenesis, immunosenescence, memory function, and oxidative stress. There is, however, limited available information on the effect of late onset DR that might have potential application to intervene in human aging. We have investigated the effect of DR initiated late in life on protein and protein degradation. Two months of DR in 23.5-month-old mice significantly reduced heat-labile altered proteins in the liver, kidney, and brain. DR reversed the age-associated increase in the half-life of proteins, suggesting that the dwelling time of the proteins is reduced in DR animals. In accordance with this observation, the activity of proteasome, which is suggested to be responsible for degradation of altered proteins, was found increased in the liver of rats 30 months of age subjected to 3.5 months of DR. Thus, DR can increase turnover of proteins, thereby possibly attenuating potentially harmful consequences by altered proteins. Likewise, DR in old rats reduced carbonylated proteins in liver mitochondria, although the effect was not observed in cytosolic proteins. Fasting induced apoA-IV synthesis in the liver of young mice for efficient mobilization of stored tissue fats, while it occurred only marginally in the old. DR for 2 months from 23 months of age partially restored inducibility of this protein, suggesting the beneficial effect of DR. Taking all these findings together, it is conceivable that DR conducted in old age can be beneficial not only to retard age-related functional decline but also to restore functional activity in young rodents. Interestingly, recent evidence that involves DNA array gene expression analysis supports the findings on the age-related decrease in protein turnover and its reversion by late-onset DR.

Aging↗