National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
DNA damage response in mammalian oocytes
Vachová, Veronika ; Šolc, Petr (advisor) ; Nevoral, Jan (referee)
During early embryonic development oocytes are arrested in prophase I of the first meiotic division, in which they can persist for years. After reaching sexual maturity and the luteinizing hormon surge resumption of meiosis and meiotic maturation occur. Oocytes are arrested again at metaphase of the second meiotic division. At this stage they are ovulated and waiting for a fertilisation. Oocytes are during their development exposed to factors that cause DNA damage, of which DNA double-strand breaks (DSBs) are the most serious threat. The maintaining of genome integrity is crucial for quality of oocytes, fertility and proper embryonic development. The mechanism of the oocyte response to DSBs presence is not fully understood and it seems to differ from somatic cells. We assume that DSBs are repaired during meiotic maturation probably by a mechanism of homologous recombination (HR). In this thesis we focuse on essencial recombinase RAD51, which participates in the repair by HR. We found that RAD51 inhibition leads to an increase of segregation errors in anaphase I. Using high resolution live cell imaging we observed chromosomal fragments and anaphase bridges. Immunofluorescence detection of DSBs-marker γH2AX showed increased amount of DSBs in prophase I and MII stage after RAD51 inhibition. Our data...
A DNA double-strand break repair and it's disorders with a relationship to the cancerogenesis
Komžák, Josef ; Ševčík, Jan (advisor) ; Vopálenský, Václav (referee)
The DNA-double strand break (DSB) repair has an essential importance for the genomic integrity maintenance. The main DSB repair pathways are homologous recombination (HR), non-homologous end joining (NHEJ) and single-strand annealing (SSA). The most important protein factors contributing to the maintenance of genomic integrity by direct participation in DSB repair are MRN, ATM, Rad51, BRCA1/2 and PALB2 in the case of HR; Ku70/80 DNA-PKcs, XRCC4 and DNA ligase IV in the case of NHEJ and Msh2-Msh3 and Rad1- Rad10 in the case of SSA. If mutated, these proteins can cause the inability to repair DNA lesions leading to a malignant transformation. The predominant phenotype manifestation of BRCA1/2 inactivation is the hereditary breast and/or ovarian cancer (HBOC). Mutations in ATM have been described as a cause of ataxia telangiectasia and inactivation of NBN gene (Nbs1 protein) causes the Nijmegen breakage syndrome. Other syndromes connected with defects in a DSB repair pathways are Fanconi anemia and Werner syndrome. Detail knowledge of DSB repair process is a mandatory for diagnostics and effective therapy of a number of malignances. An example of practical and clinically relevant utilization of current knowledge about the DSB repair process is the concept of a synthetic lethality as a specific therapy. This...

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