Acquired somatic mutations in the microsatellite DNA, in children with bronchial asthma

Genomic instability and the link to infertility: A focus on microsatellites and genomic instability syndromes

Infertility is associated to multiple types of different genomic instabilities and is a genetic feature of genomic instability syndromes. While the mismatch repair machinery contributes to the maintenance of genome integrity, surprisingly its potential role in infertility is overlooked. Defects in mismatch repair mechanisms contribute to microsatellite instability and genomic instability syndromes, due to the inability to repair newly replicated DNA. This article reviews the literature to date to elucidate the contribution of microsatellite instability to genomic instability syndromes and infertility. The key findings presented reveal microsatellite instability is poorly researched in genomic instability syndromes and infertility.

Molecular characterization of redox mechanisms in allergic asthma

OBJECTIVE

To investigate the molecular redox mechanisms in allergic asthma and to examine current studies of the disease to provide a basis for further investigation of oxidative stress in allergic asthma and the signaling cascades involved in its pathogenesis.

DATA SOURCES

Through the use of PubMed, a broad biomedical literature review was conducted in the following areas related to the physiology and pathobiology of asthma: redox therapy, reactive oxygen species (ROS), oxidative stress, allergic asthma, and antioxidants.

STUDY SELECTIONS

Studies pertaining to oxidative stress and redox signaling in the molecular pathways of inflammation and hypersensitivity in the pathogenesis of allergic asthma were reviewed.

RESULTS

Allergic asthma is associated with an increase in endogenous ROS formation, leading to oxidative stress-induced damage to the respiratory system and mitigated antioxidant defenses. Exposure to environmental antigens has been shown to stimulate overproduction of ROS, resulting in abnormal physiologic function of DNA, proteins, and lipids that clinically can augment bronchial hyperresponsiveness and inflammation. Through the use of animal and human studies, oxidative stress has been determined to be important in the pathogenesis of allergic asthma. Thus, recent research suggests that the assessment of oxidative stress byproducts represents a novel method by which disease severity can be monitored. In addition, the use of redox-based therapy to attenuate levels of ROS presents a potential strategy to alleviate oxidative stress-induced airway inflammation in patients with asthma.

CONCLUSION

Redox mechanisms of oxidative stress in allergic asthma appear to play a key role in the pathogenesis of the disease and represent a promising therapeutic target.

Patterns of evolutionary conservation of microsatellites (SSRs) suggest a faster rate of genome evolution in Hymenoptera than in Diptera

Microsatellites, or simple sequence repeats (SSRs), are common and widespread DNA elements in genomes of many organisms. However, their dynamics in genome evolution is unclear, whereby they are thought to evolve neutrally. More available genome sequences along with dated phylogenies allowed for studying the evolution of these repetitive DNA elements along evolutionary time scales. This could be used to compare rates of genome evolution. We show that SSRs in insects can be retained for several hundred million years. Different types of microsatellites seem to be retained longer than others. By comparing Dipteran with Hymenopteran species, we found very similar patterns of SSR loss during their evolution, but both taxa differ profoundly in the rate. Relative to divergence time, Diptera lost SSRs twice as fast as Hymenoptera. The loss of SSRs on the Drosophila melanogaster X-chromosome was higher than on the other chromosomes. However, accounting for generation time, the Diptera show an 8.5-fold slower rate of SSR loss than the Hymenoptera, which, in contrast to previous studies, suggests a faster genome evolution in the latter. This shows that generation time differences can have a profound effect. A faster genome evolution in these insects could be facilitated by several factors very different to Diptera, which is discussed in light of our results on the haplodiploid D. melanogaster X-chromosome. Furthermore, large numbers of SSRs can be found to be in synteny and thus could be exploited as a tool to investigate genome structure and evolution.

Oxidative DNA damage and somatic mutations: a link to the molecular pathogenesis of chronic inflammatory airway diseases

BACKGROUND

Acquired somatic mutations induced by oxidative stress may contribute to the molecular pathogenesis of chronic inflammatory airway diseases. The objective of this study was to assess the intensity of oxidative DNA damage and the presence of microsatellite DNA instability (MSI), a marker of acquired somatic mutations, in patients with COPD, patients with noncystic fibrosis bronchiectasis, and control subjects.

METHODS

Induced sputum and peripheral blood from 97 subjects were analyzed; 36 patients with COPD, 36 patients with bronchiectasis, 15 smokers without COPD, and 10 healthy control subjects. DNA was extracted and analyzed for MSI. 8-hydroxy-2'-deoxyguanosine (8-OHdG), a specific marker of oxidant-induced DNA damage, was measured in serum and sputum supernatants.

RESULTS

None of the patients with bronchiectasis or control subjects (non-COPD smokers, healthy subjects) exhibited any genetic alteration. In contrast, MSI was found in 38% of COPD specimens. Sputum 8-OHdG was statistically significantly increased in COPD when compared with subjects with bronchiectasis (P = .0002), smokers without COPD (P = .0056), and healthy subjects (P = .0003). Sputum 8-OHdG in MSI-positive patients with COPD differed significantly from that of MSI-negative patients with COPD (P = .04) and smokers without COPD (P = .008), but was not statistically different (P = .07) among MSI-negative patients with COPD and smokers without COPD. Serum 8-OHdG was significantly increased in MSI-positive compared with MSI-negative patients with COPD (P = .001), but was not statistically significant in smokers without COPD (P = .09). Serum 8-OHdG was increased in smokers without COPD compared with MSI-negative patients with COPD (P = .009).

CONCLUSIONS

There is a clear disparity in COPD regarding oxidant-induced DNA damage and somatic mutations. This may reflect a difference in the oxidative stress per se or a deficient antioxidant and/or repair capacity in the lungs of patients with COPD.