Accumulation Of Carbonyls Research Articles

Commentary on "Protein Carbonyl Accumulation in Aging Dauer Formation-Defective (daf) Mutants of Caenorhabditis elegans"

Commentary on "Protein Carbonyl Accumulation in Aging Dauer Formation-Defective (daf) Mutants of Caenorhabditis elegans"

Accumulation of carbonyls accelerates the formation of pentosidine, an advanced glycation end product: carbonyl stress in uremia.

Advanced glycation end product (AGE) formation is related to hyperglycemia in diabetes but not in uremia, because plasma AGE levels do not differ between diabetic and nondiabetic hemodialysis patients. The mechanism of this phenomenon remains elusive. Previously, it was suggested that elevation of AGE levels in uremia might result from the accumulation of unknown AGE precursors. The present study evaluates the in vitro generation of pentosidine, a well identified AGE structure. Plasma samples from healthy subjects and nondiabetic hemodialysis patients were incubated under air for several weeks. Pentosidine levels were determined at intervals by HPLC assay. Pentosidine rose to a much larger extent in uremic than in control plasma. Pentosidine yield, i.e., the change in pentosidine level between 0 and 4 wk divided by 28 d, averaged 0.172 nmol/ml per d in uremic versus 0.072 nmol/ml per d in control plasma (P < 0.01). The difference in pentosidine yield between uremic and control plasma was maintained in samples ultrafiltrated through a filter with a 5000-Da cutoff value and fortified with human serum albumin (0.099 versus 0.064 nmol/ml per d; P < 0.05). Pentosidine yield was higher in pre- than in postdialysis plasma samples (0.223 versus 0.153 nmol/ml per d; P < 0.05). These results suggest that a large fraction of the pentosidine precursors accumulated in uremic plasma have a lower than 5000 Da molecular weight. Addition of aminoguanidine and OPB-9195, which inhibit the Maillard reaction, lowered pentosidine yield in both uremic and control plasma. When ultrafiltrated plasma was exposed to 2,4-dinitrophenylhydrazine, the yield of hydrazones, formed by interaction with carbonyl groups, was markedly higher in uremic than in control plasma. These observations strongly suggest that the pentosidine precursors accumulated in uremic plasma are carbonyl compounds. These precursors are unrelated to glucose or ascorbic acid, whose concentration is either normal or lowered in uremic plasma. They are also unrelated to 3-deoxyglucosone, a glucose-derived dicarbonyl compound whose level is raised in uremic plasma: Its addition to normal plasma fails to increase pentosidine yield. This study reports an elevated level of reactive carbonyl compounds ("carbonyl stress") in uremic plasma. Most have a lower than 5000 Da molecular weight and are thus partly removed by hemodialysis. Their effect on pentosidine generation can be inhibited by aminoguanidine or OPB-9195. Carbonyl stress might contribute to AGE modification of proteins and thus to clinically relevant complications of uremia.

Effects of Oxygen on Protein Carbonyl and Aging in Caenorhabditis elegans Mutants With Long (age-1) and Short (mev-1) Life Spans

Protein carbonyl accumulation is an indicator of oxidative damage during aging. The relationship between oxidative stress and protein carbonylation during aging was studied by using a long (age-1) and a short (mev-1) life span mutant of Caenorhabditis elegans. Protein carbonyl concentrations were similar in young adults of both mutants and wild type; however, the subsequent age-dependent accumulation was different with the genotype. The mev-1 mutant (with 50% superoxide dismutase activity) accumulated protein carbonyl at a faster rate than did wild type, whereas the age-1 mutant exhibited no obvious increase except a significant accumulation at the end of extended life span. Exposure to 70% oxygen between the ages of 4 and 11 days caused afar greater accumulation of carbonyl in mev-1 than in wild type, but not in age-1. In addition, rates of aging were enhanced by oxygen in a concentration-dependent fashion. The age-1 mutant was more resistant to, but mev-1 was more sensitive to, such oxygen enhancements of aging than was wild type. These results provide further evidence that oxidative damage is one of the major causal factors for aging in C. elegans, and that the age-1 and mev-1 genes govern resistance to oxidative stress.

Study of protein carbonyls in subcellular fractions isolated from liver and spleen of old and γ-irradiated rats

Age- and γ-irradiation-dependent accumulation of oxidatively modified proteins (measured as carbonyl level) was studied in cytoplasm, mitochondria and nuclei isolated from spleen and liver of 4- and 26-month-old rats. The protein carbonyl levels significantly increased with age in all fractions studied. The carbonyl content was found to be two times higher in the nuclei than in the mitochondria and cytoplasm, which may be related to an extensive modification of lysine and arginine residues in histone molecules. γ-Irradiation of rats with 10 Gy caused a rise of protein carbonyls only in their cytoplasm and mitochondria, which was prevented in the animals fed with antioxidants and vitamins for a month before the irradiation. We observed an activation of histone-specific proteases in the nuclei of γ-irradiated rats. The lack of carbonyl accumulation in the nuclear proteins isolated from tissues of γ-irradiated animals may be explained by the degradation of oxidized histones by these proteases.

Age-dependent accumulation of dolichol in rat liver: is tissue dolichol a biomarker of aging?

Dolichols are long hydrophobic molecules broadly distributed in all tissues and cellular membranes of eukariotic cells. Dolichol affects membrane structure and fluidity, membrane-associated protein activities, and membrane sensitivity to oxidative stress. Reports have shown that dolichols exhibit a remarkable (6- to 30-fold) age-related increase in the tissues of adult and mature rats and of old flies, mice, and humans. In our longitudinal study, the age-related accumulation of dolichol was monitored in the liver tissue of male Sprague Dawley rats fed ad libitum up to age of 27 months. In addition 24-month-old rats subjected to different regimens of anti-aging diet restriction (40% calorie restriction or every-other-day feeding ad libitum) were tested. A parallel study of the accumulation of carbonyl in liver protein (a proposed biomarker of aging) was made. In addition, the age-related decline of liver autophagy/proteolysis was studied in isolated liver cells, in view of the essential role of this function in liver membrane maintenance. Results show that an age-dependent accumulation of dolichol can be observed in the liver of the rats fed ad libitum but not in the liver of 24-month-old food-restricted rats, that accumulation of dolichol precedes the accumulation of altered liver proteins, and that dolichol accumulation is accompanied by a decline in liver autophagy. It is concluded that dolichol accumulation satisfies the proposed primary and secondary applicable criteria and the desirable features required to be qualified as a biomarker of aging.

Macromolecular carbonyls in human stratum corneum: a biomarker for environmental oxidant exposure?

The presence of stratum corneum carbonyls may serve as an intrinsic dosimeter for environmental oxidative damage to skin. To investigate the accumulation of carbonyls in human stratum corneum, skin was tape-stripped, then tapes were sequentially incubated with 2,4-dinitrophenyl hydrazine (DNPH), rat anti-DNP, mouse anti-rat IgG conjugated with alkaline phosphatase, p-nitrophenyl phosphate and absorbance (405 nm) measured and carbonyls estimated. Stratum corneum exposed in vitro to oxidants: hypochlorous acid (1, 10, 100 mM), ozone (0, 1, 5, 10 ppm for 2 h) or UV light (280–400 nm; 0, 4, 88, or 24 J/cm 2) contained increased carbonyls. Furthermore, stratum corneum carbonyls were elevated in tanned compared with untanned sites: dorsal hand (0.43±0.06 nmol/cm 2) vs. lower arm (0.32±0.04, mean±S.E.M., n=11; P<0.003) and lower back (0.26±0.02) vs. buttock (0.21±0.02; n=6, P<0.01) indicating in vivo oxidative damage.

Vitamin C prevents oxidative damage.

Ascorbate-deficiency leads to extensive oxidative damage of proteins and protein loss in the guinea pig tissue microsomes as evidenced by sodium dodecyl sulfate polyacrylamide gel electrophoresis, accumulation of carbonyl, bityrosine as well as by tryptophan loss. Oxidative damage is reversed by ascorbate therapy. Oxidative damage in ascorbate deficiency also leads to lipid peroxidation in guinea pig tissue microsomes as evidenced by accumulation of conjugated dienes, malondialdehyde and fluorescent pigment. Lipid peroxides, disappear after ascorbate therapy but not by vitamin E. The observations substantiate the previous in vitro findings that ascorbate specifically prevents oxidative degradation of microsomal membranes. The results indicate that vitamin C may exert a powerful protection against degenerative diseases associated with oxidative damage and play a critical role in wellness and health maintenance.

The non-sensitized photo-oxidative degradation of polycarproamide

The viscometric method was used to measure the rate of photo-oxidative degradation of polycaproamide (PCA) specimens prepared under varying polymerization conditions. Thin PCA films (1–3 μ) were exposd to the action of light at 253·7 nm in air at room temperature. It is shown that in the early stages of photooxidation (up to 3% of oxidized substance) the photo-oxidative degradation of the PCA specimens is non-sensitized, and is determined by the absorption of the amide chromophore group, and does not depend on the accumulation of photo-oxidation products. The quantum yeilds of fractured bonds in the PCA and the accumulation of carbonyl and carboxyl groups were found to be 0·015, 0·009 and 0·0045 respectively.