Deoxyribonucleic Acid Repair Enzymes Research Articles

Ultraviolet B-Rays Induced Gene Alterations and DNA Repair Enzymes in Skin Tissue.

Ultraviolet (UV) radiation leads to deoxyribonucleic acid (DNA) damage and changes in gene expression. Topical DNA repair enzymes in liposomes are capable of undoing this damage. To evaluate gene expression changes induced by ultraviolent B-rays (UVB) light and assess the effect of topical DNA repair enzymes extracted from Micrococcus luteus (M. luteus) and photolyase in modifying these changes. Non-invasive, adhesive patch collection kits were used to sample skin on the right and left post-auricular areas before and 24 hours after UVB exposure (n=48). Subjects applied topical DNA repair enzymes to the right post-auricular area daily for 2 weeks. Subjects returned 2 weeks later for repeat non-invasive skin sample collection. Eight of 18 tested genes demonstrated significant changes 24 hours following UVB exposure. DNA repair enzymes from M. luteus or photolyase had no significant effect on genetic expression compared with the control at 2 weeks post UV exposure. UVB exposure causes acute changes in gene expression, which may play roles in photo-aging damage and skin cancer growth and regulation. While non-invasive gene expression testing can detect UV damage, additional genomic studies investigating recovery from UV damage at different time periods are needed to establish the potential of DNA repair enzymes to minimize or reverse this damage. J Drugs Dermatol. 2023;22(5): doi:10.36849/JDD.7070.

Fumarase affects the deoxyribonucleic acid damage response by protecting the mitochondrial desulfurase Nfs1p from modification and inactivation

SummaryThe Krebs cycle enzyme fumarase, which has been identified as a tumor suppressor, is involved in the deoxyribonucleic acid (DNA) damage response (DDR) in human, yeast, and bacterial cells. We have found that the overexpression of the cysteine desulfurase Nfs1p restores DNA repair in fumarase-deficient yeast cells. Nfs1p accumulates inactivating post-translational modifications in yeast cells lacking fumarase under conditions of DNA damage. Our model is that in addition to metabolic signaling of the DDR in the nucleus, fumarase affects the DDR by protecting the desulfurase Nfs1p in mitochondria from modification and inactivation. Fumarase performs this protection by directly binding to Nfs1p in mitochondria and enabling, the maintenance, via metabolism, of a non-oxidizing environment in mitochondria. Nfs1p is required for the formation of Fe–S clusters, which are essential cofactors for DNA repair enzymes. Thus, we propose that the overexpression of Nfs1p overcomes the lack of fumarase by enhancing the activity of DNA repair enzymes.

Distance-Based Biosensor for Ultrasensitive Detection of Uracil-DNA Glycosylase Using Membrane Filtration of DNA Hydrogel.

In the deoxyribonucleic acid (DNA) repair pathways, DNA repair enzymes have great significance for genomic integrity. As one important initiator of the base-excision repair pathway, the aberrant activity of uracil-DNA glycosylase (UDG) is closely associated with many diseases. Herein, we developed a simple distance-based device for visual detection of UDG activity using a load-free DNA hydrogel. The DNA hydrogel consists of polyacrylamide-DNA chains being bridged by a single-stranded DNA crosslinker containing a responsive uracil base site. UDG can recognize and remove the uracil, resulting in the cleavage effect of the DNA crosslinker strand with the assistance of endonuclease IV (Endo IV). Plugging one end of the capillary tube, the DNA hydrogel acting as a filter membrane separator would control molecules to flow into the tube. The integrity of the DNA hydrogel networks is affected by the excision of UDG. Therefore, taking full advantage of membrane filtration of the DNA hydrogel, the activity of UDG can be quantitatively detected via reading the distance of the red indicator solution in the capillary tube. Without any instruments and complicated procedures, this method realizes high sensitivity and specificity for the detection of UDG as low as 0.02 mU/mL and can even measure UDG in complex cell samples. Additionally, this method is simple, universal, and can be used to screen inhibitors, which shows great potential for point-of-care testing, clinical diagnosis, and drug discovery.

A Src/Abl kinase inhibitor, bosutinib, downregulates and inhibits PARP enzyme and sensitizes cells to the DNA damaging agents

Abstract Background Poly(ADP-ribosyl)ation (PARylation) catalyzed mainly by PARP1 is a highly regulated posttranslational modification associated with several pathways in cellular physiology and genotoxic deoxyribonucleic acid (DNA) damage response. PAR polymers and PARP enzyme function in DNA integrity maintenance and several PARP inhibitors have entered clinical phase studies for cancer therapies. Material and methods The effect of bosutinib, a dual Src/Abl kinase inhibitor, on PARylation was fluorometrically measured. The cytotoxic and chemosensitizing effects were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The levels of DNA repair proteins and PARP enzyme were examined by immunoblotting. Results In this study, bosutinib is characterized as a novel PARP inhibitor. Bosutinib inhibited oxidative stress-induced cellular PARylation and nuclear foci formation by downregulating PARP1 levels. Bosutinib was found to be more cytotoxic on Capan1 cells with BRCA2 mutation. Furthermore by acting as a chemosensitizer, bosutinib enhanced the cytotoxicity of doxorubicin (DOXO) and etoposide (ETP) by decreasing phosphorylation of DNA repair enzymes checkpoint kinase 1 (Chk1) and ataxia-telangiectasia mutated (ATM). Conclusion By inhibition of both PARP and DNA damage checkpoint kinases, bosutinib increased the phospho-H2AX levels, an early indicator of DNA double strand breaks.

Advancement in skin aging: the future cosmeceuticals

Aging is a multifactorial process defined as the accumulation of damage. The aging of the skin is characterized by specific clinical end points, the cause of which is not always thoroughly understood. The skin is exposed to environmental aggressions and the reactive oxygen species produced during cellular metabolism. Damage to the cellular and extracellular components of the skin can be avoided or removed by the appropriate topical application of active ingredients. Sunscreens are essential to avoid damage from the most important damaging environmental agent: solar radiation. Liposomes containing deoxyribonucleic acid repair enzymes and accelerate the endogenous removal of pyrimidine dimers after exposure to ultraviolet radiation. Specific antioxidants reduce the rate of formation of secondary ultraviolet-induced damages, particularly those induced by singlet oxygen. Anti-inflammatory agents, immunostimulants, and enhancers of molecular and cellular detoxification could enter the panoply of new cosmeceuticals to avoid age spots, dark circles, wrinkles, and other clinical aspects of skin aging.

Deoxyribonucleic acid damage/repairproteins are elevated in the failing human myocardium due to idiopathic dilated cardiomyopathy

ObjectivesThe study investigated the expression and relationship of deoxyribonucleic acid (DNA) repair enzymes with hemodynamic and nitric oxide (NO)-mediated stress in the failing myocardium. BackgroundThe role of apoptosis in human heart failure is controversial. Experimental studies suggested that NO-mediated stress modulates apoptosis of the cardiac myocytes. Of note, DNA repair enzymes such as redox factor/apurinic/apyridimine endonuclease Ref-1 protein, proliferative cell nuclear antigen (PCNA), the poly (ADP-ribose) polymerase (PARP), and DNA-protein kinase (DNA-PK) determine the cell fate after the DNA damage. MethodsLeft ventricular (LV) endomyocardial biopsies from 23 patients with dilated cardiomyopathy were analyzed by immunohistochemistry. ResultsTerminal deoxynucleotidyltransferase-mediated biotin-dUTP nick-end labeling (TUNEL) or cleaved caspase-3 and cleaved PARP could not be detected. The number of Ref-1-positive myocytes tended to be higher in patients with LV ejection fraction (EF) ≤35% versus LV EF >35% (21.23 ± 4.8% vs. 13.8 ± 5.8%, p = 0.1). The PCNA (7.1 ± 2.8% vs. 0.9 ± 0.6%, p = 0.05) and DNA-PK expressions (39.5 ± 5.4% vs. 8.6 ± 5.5%, p < 0.01) were higher in patients with LVEF ≤35% vs. LVEF >35%. The PCNA, Ref-1, and DNA-PK expression correlated with the LV end-systolic wall stress (r = 0.61, p < 0.01; r = 0.52, p < 0.01; and r = 0.73, p < 0.001, respectively). In addition, the PCNA and DNA-PK expression correlated with inducible NO synthase (r = 0.41, p = 0.05, and r = 0.53, p < 0.01, respectively). ConclusionsIn this study, apoptosis could not be detected in the failing myocardium owing to idiopathic dilated cardiomyopathy. In contrast, failing myocardium was characterized by active DNA repair that was associated with elevated LV wall stress and activation of the inducible NO synthase.

Coding properties of poly(deoxycytidylic acid) templates containing uracil or apyrimidinic sites: in vitro modulation of mutagenesis by deoxyribonucleic acid repair enzymes.

Heat treatment of poly(deoxycytidylic acid)-[poly(dC)] induces the formation of dUMP residues, which code for dAMP when replicated by Escherichia coli DNA polymerases I and III. The specificity of dUMP coding properties is indicated by the quantitative relation between the dAMP incorporated and the frequency of dUMP residues in the heat-treated poly(dC). The dAMP incorporation is prevented by preincubation of uracil containing poly(dC) with uracil-DNA glycosylase. The excision of uracil by uracil-DNA glycosylase leads to the formation of apyrimidinic sites (AP sites), which are barely replicated in vitro under physiological conditions. However, the alteration of E. coli DNA polymerase I fidelity of replication by Mn2+ greatly stimulates the replication of AP sites. There is a preferential incorporation of dAMP, as compared to dTMP, opposite the AP sites. The dAMP incorporation is prevented by preincubation of poly(dC) containing AP sites with Micrococcus luteus AP endonuclease B. The results show a close association between DNA repair by base excision and the prevention of mutagenic processes in vitro. Furthermore, since the alteration of DNA polymerase fidelity allows some replication of the noncoding DNA lesion (AP site), this could imply a role in SOS-induced mutagenesis in vivo.

Regulation of ribonucleoside diphosphate reductase synthesis in Escherichia coli: increased enzyme synthesis as a result of inhibition of deoxyribonucleic acid synthesis.

Inhibition of deoxyribonucleic acid (DNA) synthesis in Escherichia coli by chemical inhibitors or by shifting cultures of temperature-sensitive elongation (dnaE and dnaB) or initiation (dnaA) mutants to nonpermissive conditions led to greatly increased synthesis of the enzyme ribonucleoside diphosphate reductase, which catalyzes the first reaction unique to the pathway leading to DNA replication. In contrast to the Gudas and Pardee proposed model for control of the synthesis of DNA repair enzymes, in which both DNA inhibition and DNA degradation are involved, DNA synthesis inhibition in recA, recB, recC, or lex strains results in increased synthesis of ribonucleotide reductase, which suggests that DNA degradation is not required. We propose that inhibition of DNA synthesis causes a cell to accumulate an unknown compound that stimulates the initiation of a new round of DNA replication, and that this same signal is used to induce ribonucleotide reductase synthesis.

Influence of thymine starvation on the integrity of deoxyribonucleic acid in Escherichia coli.

The influence of thymine starvation on the single-strand molecular weight of deoxyribonucleic acid (DNA) from Escherichia coli was determined by sedimentation through gradients of alkaline sucrose. Growth of cells for as long as 150 min in thymineless medium did not significantly reduce the molecular weight below the control value of 2.4 +/- 0.3 x 10(8) daltons. Incubation of cells in thymineless medium after exposure to 500 ergs/mm(2) of ultraviolet light or 20 krad of (137)Cs gamma rays did not appear to block the rejoining of single-strand breaks associated with irradiation. Thus, DNA repair enzymes, presumably including DNA ligase, are not significantly inhibited by thymine starvation.