Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of 8-oxo-2'-deoxyguanosine (8-oxo-dG) (8-hydroxydeoxyguanosine)--a DNA base damage product induced by oxygen radicals and irradiation on survival and mutagenesis in Escherichia coli strains C-600 and P-687 was investigated. Survival and mutagenesis curves, in dependence of 8-oxo-dG concentrations in the medium, ranging from 0.2 through 10 mM, were obtained. Bacterial survival at all 8-oxo-dG concentrations tested was shown to be no lesser than in the control. The mutagenic effect of 8-oxo-dG was tested by frequency of reversions in the absence of leucine and threonine. A non-linear dependence of mutagenesis on the concentration was observed. Linear increase in the amount of revertants took place at concentrations of 8-oxo-dG lower than 1 mM, and being kept constant at higher concentrations. Induction of SOS repair under the action of 8-oxo-dG in E. coli PQ37 strain was estimated according to alteration of activity of beta-galactosidase in the SOS chromotest. Weak induction of the SOS response was observed within the wide range of 8-oxo-dG concentration values, which points to a lack of genotoxicity and independence of mutagenesis on SOS repair.
 ...
PMID:[Mutagenic effect on Escherichia coli bacteria of 8-hydroxy-2'-deoxyguanosine--a DNA base damage product induced by oxygen radicals and ionizing radiation]. 142 57

Cause-effect relationships between oxidative stress, DNA damage and aging were investigated in WI-38 human diploid fibroblasts at 21, 41 or 58 population doublings (PDs), corresponding to young, middle age or old fibroblasts, respectively. Oxidative DNA damage was evaluated by immunohistochemical detection of 8-hydroxy-2'deoxyguanosine (8-OHdG) adducts or by single cell microgel electrophoresis (COMET assay). Aging was evaluated by growth rate, senescence-associated-beta-galactosidase (SA-beta galactosidase) activity, cell cycle distribution, and expression of p21. Our results demonstrate that (i) oxidative DNA damage is proportional to the age of cells (ii) DNA damage in old/58 PDs cells reflects both an increased susceptibility to oxidative stress, induced by acute exposure to sub-lethal concentrations of hydrogen peroxide (H(2)O(2)), and a reduced efficiency of repair mechanisms. We also show that mild chronic oxidative stress, induced by prolonged exposure to 5 microM H(2)O(2), accelerates aging in fibroblasts. In fact, this treatment increased 8-OHdG levels, SA-beta-galactosidase activity, and G0/G1 cell cycle arrest in middle age/41 PDs, making them similar to H(2)O(2)-untreated old/58 PDs cells. Although other mechanisms may concur in mediating the effects of H(2)O(2), these results lend support to the concept that oxidative stress may be a key determinant of aging. Measurements of oxidative DNA damage might therefore be exploited as reliable marker of cellular aging.
 ...
PMID:Oxidative DNA damage as a marker of aging in WI-38 human fibroblasts. 1190 82

Glucose-6-phosphate dehydrogenase (G6PD) is involved in the generation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) and the maintenance of cellular redox balance. We previously showed that G6PD-deficient fibroblasts undergo growth retardation and premature cellular senescence. In the present study, we demonstrate abatement of both the intracellular G6PD activity and the ratio NADPH/NADP(+) during the serial passage of G6PD-deficient cells. This was accompanied by a significant increase in the level of 8-hydroxy-2-deoxyguanosine (8-OHdG). This suggests that the lowered resistance to oxidative stress and accumulative oxidative damage may account for the premature senescence of these cells. Consistent with this, the G6PD-deficient cells had an increased propensity for hydrogen peroxide (H(2)O(2))-induced senescence; these cells exhibited such senescent phenotypes as large, flattened morphology and increased senescence-associated beta-galactosidase (SA-beta-Gal) staining. Decreases in both the intracellular G6PD activity and the NADPH/NADP(+) ratio were concomitant with an increase in 8-OHdG level in H(2)O(2)-induced senescent cells. Exogenous expression of G6PD protected the deficient cells from stress-induced senescence. No significant telomere shortening occurred upon repetitive treatment with H(2)O(2). Simultaneous induction of p16(INK4a) and p53 was detected in G6PD-deficient but not in normal fibroblasts during H(2)O(2)-induced senescence. Our findings support the notion that G6PD status, and thus proper redox balance, is a determinant of cellular senescence.
 ...
PMID:Glucose-6-phosphate dehydrogenase-deficient cells show an increased propensity for oxidant-induced senescence. 1498 Jul 2

Previous studies have shown that glucose-6-phosphate dehydrogenase (G6PD)-deficient cells are under increased oxidative stress and undergo premature cellular senescence. The present study demonstrates that G6PD-deficient cells cultured under 3% oxygen concentration had an extended replicative lifespan, as compared with those cultured under atmospheric oxygen level. This was accompanied by a reduction in the number of senescence-associated beta-galactosidase (SA-beta-Gal) positive and morphologically senile cells at comparable population doubling levels (PDL). Concomitant with the extension of lifespan was decreased production of reactive oxygen species. Additionally, lifespan extension was paralleled by the greatly abated formation of such oxidative damage markers as 8-hydroxy-deoxyguanosine (8-OHdG) as well as the oxidized and cross-linked proteins. Moreover, the mitochondrial mass increased, but the mitochondrial membrane potential DeltaPsim decreased in cells upon serial propagation. These changes were inhibited by lowering the oxygen tension. Our findings provide additional support to the notion that oxidative damage contributes to replicative senescence of G6PD-deficient cells and reduction of oxidative damage by lowering oxygen tension can delay the onset of cellular senescence.
 ...
PMID:Low oxygen tension alleviates oxidative damage and delays cellular senescence in G6PD-deficient cells. 1745 40

For the past 20 years, super-oxidised solutions (SOSs) have been shown to be potent antimicrobials and disinfectants via oxidative damage. However, the potential toxicity of SOSs on eukaryotic cells has not been documented in vitro. This is relevant because oxygen and chlorine reactive species may possibly induce ageing and irreversible cellular dysfunctions that eventually produce cell death. The present study investigates the cytotoxicity and oxidative stress induced by a novel, pH-neutral SOS (i.e. Microcyn, MCN) on young, primary diploid - human dermal fibroblast (HDF) cultures. For this purpose, hydrogen peroxide (HP) was used as a positive control of oxidative damage. When these solutions were used at concentrations indicated for wound care (i.e. undiluted MCN or 880 mM HP), HP was significantly more toxic than MCN. After 5 and 30 minutes of exposure, cell viability was 38% and 5%, respectively, in 880 mM HP-treated cells versus 75% and 70% in MCN-treated populations, respectively. HP induced both apoptosis and necrosis, whereas MCN induced only necrosis. Genotoxic and ageing studies were then conducted at sublethal HP concentrations as previously reported in the literature. Cellular DNA and RNA were partially degraded only in HDFs exposed to 500 microM HP for 30 minutes but not in those exposed to undiluted MCN. At this same concentration, HP induced the formation of 8-hydroxy-2'deoxyguanosine adducts in HDFs but this effect was neither observed in control- nor observed in MCN-treated cells. HDFs were further exposed to 5 microM HP or 10% MCN for 1 month. The expression of senescence-associated-beta-galactosidase was only significantly elevated in cells chronically exposed to 5 microM HP. Altogether, these results show that MCN is significantly less cytotoxic than antiseptic HP concentrations (i.e. 880 mM) and that, in vitro, it does not induce genotoxicity or accelerated ageing.
 ...
PMID:Effects of pH-neutral, super-oxidised solution on human dermal fibroblasts in vitro. 1792 80

We have reported a possible involvement of apurinic/apyrimidinic endonuclease 1 (APE1), one of the DNA repair pathways, in various nephropathy models and found that there is a close connection between APE1 and p53-dependent apoptosis. Therefore, we investigated the changes of APE in aging rat kidney since aging is the consequence of increased susceptibility to apoptosis and impaired repair. Characteristics of chronological aging were compared among 6-, 24- and 28-month-old male Sprague-Dawley rats. Serum blood urea nitrogen and creatinine were measured for renal function. Western blot assay was compared for p53, bax, cleaved caspase 3, rH2AX, and APE1. Immunohistochemical staining of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and APE1 was performed. Cellular senescence was checked by beta-galactosidase staining. Compared with young rats, aged rats showed significant increase in creatinine level with cellular senescence in the proximal convoluted tubules confirmed by beta-galactosidase staining. All the checked variables were significantly increased with aging: 1) increased p53, bax, and caspase 3 may activate the apoptotic pathway, 2) increased rH2AX and 8-OHdG immunolocalization in the proximal convoluted tubules might mean augmented DNA damage, and 3) increased APE1 might be caused by the immunoreactivity in the distal convoluted tubules while decreased in the proximal convoluted tubules. These results suggested that APE1 might have little protective effects on p53-dependent apoptosis irrespective of DNA repair activities in aged renal proximal tubules. Therefore, researchers should use older animals than 24-month-old rats in future studies for investigating the relationship between the apoptosis and DNA repair in the aging kidneys.
 ...
PMID:Apurinic/apyrimidinic endonuclease 1 on aging-associated deteriorations in rat kidneys. 2536 96