mRAD18Sc: a Multifunctional Protein in Replicative Damage Bypass and Gametogenesis

__Abstract__ Integrity of the genome is of vital importance for life. DNA is constantly under attack from endogenous and exogenous DNA damaging agents. During each round of DNA replication, the replication machinery requires the presence of an intact DNA template. If a DNA lesion is encountered, progression of the replication process is at risk to be blocked. However, replicative damage bypass prevents termination of DNA replication. The proteins that act in replicative damage bypass are capable to operate as a temporary “stand-in” of the replication machinery. This process has been investigated in detail in the yeast S. cerevisiae, and it has become clear that the ubiquitin-conjugating enzyme RAD6 is a key factor in this process. To perform its function, RAD6 interacts with RAD18, an ubiquitin ligase. The aim of the research outlined in this thesis is to provide insight into the role of mammalian homologs of RAD6 and RAD18 in the process of replicative damage bypass (RDB) in somatic cells and during gametogenesis. The mammalian homologs are HR6A and HR6B for RAD6 and mRAD18Sc for RAD18. In this research, live cell imaging and fl uorescence-based technologies are applied to study the subcellular localization and dynamics of fl uorescently tagged HR6B and mRAD18Sc

DNA repair mechanisms and gametogenesis

In mammals, there is a complex and intriguing relationship between DNA repair and gametogenesis. DNA repair mechanisms are involved not only in the repair of different types of DNA damage in developing germline cells, but also take part in the meiotic recombination process. Furthermore, the DNA repair mechanisms should tolerate mutations occurring during gametogenesis, to a limited extent. In the present review, several gametogenic aspects of DNA mismatch repair, homologous recombination repair and postreplication repair are discussed. In addition, the role of DNA damage-induced cell cycle checkpoint control is considered briefly. It appears that many genes encoding proteins that take part in DNA repair mechanisms show enhanced or specialized expression during mammalian gametogenesis, and several gene knockout mouse models show male or female infertility. On the basis of such knowledge and models, future experiments may provide more information about the precise relationship between DNA repair, chromatin dynamics, and genomic stability versus instability during gametogenesis

Global survey of physician testing practices for nontuberculous mycobacteria

Background Certain patients are at greater risk of developing nontuberculous mycobacterial pulmonary disease (NTM-PD), including those with lung conditions such as bronchiectasis. Testing for nontuberculous mycobacteria (NTM) in patients at risk is necessary to identify NTM-PD and start appropriate management. The aim of this survey was to evaluate current testing practices for NTM and identify testing triggers. Methods Physicians (n=455) who see at least one patient with NTM-PD in a typical 12-month period and test for NTM as part of practice from Europe, USA, Canada, Australia, New Zealand and Japan participated in a 10-min anonymised survey on NTM testing practices. Results Bronchiectasis, COPD and use of immunosuppressants were the factors most likely to prompt testing among physicians in this survey (90%, 64% and 64%, respectively), with radiological findings the most common reason leading to considering NTM testing in patients with bronchiectasis and COPD (62% and 74%, respectively). Macrolide monotherapy in patients with bronchiectasis and inhaled corticosteroid use in patients with COPD were not important triggers for testing (15% and 9% of physicians, respectively). Persistent cough and weight loss triggered testing in >75% of physicians. Testing triggers were markedly different for physicians in Japan, with cystic fibrosis prompting testing in fewer physicians compared with other regions. Conclusions Testing for NTM is influenced by underlying disease, clinical symptoms or radiological changes, but clinical practice varies considerably. Adherence to guideline recommendations for NTM testing is limited in certain patient subgroups and varies across regions. Clear recommendations on NTM testing are needed