BACKGROUND: Mutations 657del5 and R215W in exon 6 of tumor suppressor gene NBS I are found in 1% Slavic populations. Increased occurrence of cancer was repeatedly reported in adult relatives of patients with Nijmegen breakage syndrome. Among children with oncological problematic, nonsignificantly increased frequency of NBS1 heterozygotes was found, which seems not to play any important role in cancerogenesis in childhood. However, the proportion of NBS heterozygotes among adult patients with malignancies could be significant and their therapy and follow up should respect their hyperradiosensitivity. METHODS AND RESULTS: Mutations in exon were studied in 706 adult patients with malignancies. We found 5 NBS heterozygotes, which not more than the population prevalence (1:129-165). Increased frequency of NBS heterozygotes was found among patients with colon and rectal cancer (2/101), breast cancer (1/60), skin malignancies (1/98). CONCLUSIONS: Surprisingly only one NBS heterozygote was found among 228 patients with nonHodgkin lymphoma, the malignancy which is a common complication in NBS homozygotes. Other types of malignancies were uncommon and only one R215W heterozygote was found. Comparison frequency of NBS heterozygotes with incidence NBS among person older than 70 years shows significant difference. Prevention of malignancies by avoidance from ionisation could be realized also in relatives of patients after identification of their genotype.

• MeSH
• dospělí MeSH
• heterozygot MeSH
• jaderné proteiny genetika   MeSH
• lidé MeSH
• mutace * MeSH
• nádory genetika   MeSH
• proteiny buněčného cyklu genetika   MeSH
• tumor supresorové geny * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• Názvy látek
• jaderné proteiny MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH

BACKGROUND: Telomeres, as elaborate nucleo-protein complexes, ensure chromosomal stability. When impaired, the ends of linear chromosomes can be recognised by cellular repair mechanisms as double-strand DNA breaks and can be healed by non-homologous-end-joining activities to produce dicentric chromosomes. During cell divisions, particularly during anaphase, dicentrics can break, thus producing naked chromosome tips susceptible to additional unwanted chromosome fusion. Many telomere-building protein complexes are associated with telomeres to ensure their proper capping function. It has been found however, that a number of repair complexes also contribute to telomere stability. RESULTS: We used Arabidopsis thaliana to study the possible functions of the DNA repair subunit, NBS1, in telomere homeostasis using knockout nbs1 mutants. The results showed that although NBS1-deficient plants were viable, lacked any sign of developmental aberration and produced fertile seeds through many generations upon self-fertilisation, plants also missing the functional telomerase (double mutants), rapidly, within three generations, displayed severe developmental defects. Cytogenetic inspection of cycling somatic cells revealed a very early onset of massive genome instability. Molecular methods used for examining the length of telomeres in double homozygous mutants detected much faster telomere shortening than in plants deficient in telomerase gene alone. CONCLUSIONS: Our findings suggest that NBS1 acts in concert with telomerase and plays a profound role in plant telomere renewal.

• MeSH
• anafáze MeSH
• Arabidopsis cytologie   enzymologie   genetika   růst a vývoj   MeSH
• chromozomální nestabilita MeSH
• chromozomy rostlin genetika   metabolismus   MeSH
• cytogenetické vyšetření MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• homeostáza telomer MeSH
• homologní protein MRE11 MeSH
• hybridizace in situ fluorescenční MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• klíčení MeSH
• květy cytologie   genetika   metabolismus   MeSH
• mapování interakce mezi proteiny MeSH
• meióza MeSH
• oprava DNA MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• rostlinné buňky enzymologie   metabolismus   MeSH
• samooplození MeSH
• semena rostlinná genetika   růst a vývoj   metabolismus   MeSH
• telomerasa genetika   metabolismus   MeSH
• telomery genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA vazebné proteiny MeSH
• homologní protein MRE11 MeSH
• jaderné proteiny MeSH
• Mre11 protein, Arabidopsis MeSH Prohlížeč
• proteiny buněčného cyklu MeSH
• proteiny huseníčku MeSH
• rad50 protein, Arabidopsis MeSH Prohlížeč
• telomerasa MeSH
• TERT protein, Arabidopsis MeSH Prohlížeč

Mutations in NBS1 gene are related to higher occurrence of malignancies. In this work we studied response of T-lymphocyte leukemia cells MOLT-4 to ionizing radiation. We detected IRIF (ionizing radiation forming foci) containing histone gammaH2A.X, protein 53BP1, and Nbs1, which were formed around double-strand breaks of DNA. We found dose-dependent increase in foci number (colocalization of gammaH2A.X and 53BP1) and gammaH2A.X amount (integral optical density) 1h after irradiation. After the dose of 1.5 Gy the number of foci decreases with time, but 72 h after irradiation 9% of live cells still contained big foci around unrepaired DNA damage. Western blot method revealed massive phosphorylation of H2A.X during apoptosis induction, 6-24 h after irradiation by the doses 1.5 and 3 Gy. Cells with apoptotic morphology showed strong phosphorylation of H2A.X, but it was not accompanied by 53BP1. 1h after irradiation by the lethal doses 5 and 10 Gy we detected by Western blot a decrease in repair proteins Mre11, Rad50, and Nbs1. While phosphorylation of H2A.X 1h after irradiation was detected by both confocal microscopy and Western blot, phosphorylation of Nbs1 on serine 343 was not detectable in MOLT-4 cells. Despite functional ATM and p53 the phosphorylation of Nbs1 on serine 343 was impaired in these cells, and might be responsible for high radiosensitivity of MOLT-4 cells.

• MeSH
• fosforylace MeSH
• jaderné proteiny metabolismus   MeSH
• leukemie T-buněčná metabolismus   radioterapie   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• oprava DNA MeSH
• poškození DNA MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• tolerance záření MeSH
• vztah dávky záření a odpovědi MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• jaderné proteiny MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH

B-Myb, a highly conserved member of the Myb transcription factor family, is expressed ubiquitously in proliferating cells and controls the cell cycle dependent transcription of G2/M-phase genes. Deregulation of B-Myb has been implicated in oncogenesis and loss of genomic stability. We have identified B-Myb as a novel interaction partner of the Mre11-Rad50-Nbs1 (MRN) complex, a key player in the repair of DNA double strand breaks. We show that B-Myb directly interacts with the Nbs1 subunit of the MRN complex and is recruited transiently to DNA-damage sites. In response to DNA-damage B-Myb is phosphorylated by protein kinase GSK3β and released from the MRN complex. A B-Myb mutant that cannot be phosphorylated by GSK3β disturbs the regulation of pro-mitotic B-Myb target genes and leads to inappropriate mitotic entry in response to DNA-damage. Overall, our work suggests a novel function of B-Myb in the cellular DNA-damage signalling.

• MeSH
• ATM protein metabolismus   MeSH
• biologické modely MeSH
• buněčné linie MeSH
• DNA vazebné proteiny chemie   metabolismus   MeSH
• dvouřetězcové zlomy DNA MeSH
• enzymy opravy DNA chemie   metabolismus   MeSH
• fosforylace MeSH
• GSK3B metabolismus   MeSH
• homologní protein MRE11 chemie   metabolismus   MeSH
• hydrolasy působící na anhydridy kyselin MeSH
• interakční proteinové domény a motivy MeSH
• jaderné proteiny chemie   metabolismus   MeSH
• lidé MeSH
• mitóza genetika   MeSH
• multiproteinové komplexy metabolismus   MeSH
• mutace MeSH
• oprava DNA MeSH
• poškození DNA * MeSH
• proteiny buněčného cyklu chemie   genetika   metabolismus   MeSH
• regulace genové exprese MeSH
• sekvence aminokyselin MeSH
• signální transdukce * MeSH
• trans-aktivátory chemie   genetika   metabolismus   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ATM protein MeSH
• DNA vazebné proteiny MeSH
• enzymy opravy DNA MeSH
• GSK3B MeSH
• homologní protein MRE11 MeSH
• hydrolasy působící na anhydridy kyselin MeSH
• jaderné proteiny MeSH
• multiproteinové komplexy MeSH
• MYBL2 protein, human MeSH Prohlížeč
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH
• RAD50 protein, human MeSH Prohlížeč
• trans-aktivátory MeSH

Nijmegen breakage syndrome is an autosomal recessive chromosomal instability syndrome characterized by microcephaly, immunodeficiency, radiosensitivity, and predisposition to lymphoid malignancy. A truncating deletion [657del(5)] in exon 6 of the nibrin NBS1 gene is the most frequent cause of the syndrome. Slavic populations carry this mutation in a high frequency. Here, we present polymerase chain reaction with sequence specific primers as a method for the detection of Slavic NBS1 mutation and confirm the high carrier frequency in the Czech population (combined frequency from both studies: 1/106, 95% CI = 1/331 to 1/46).

• MeSH
• chromozomální delece * MeSH
• DNA primery genetika   MeSH
• dospělí MeSH
• frekvence genu genetika   MeSH
• heterozygot MeSH
• jaderné proteiny genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mutační analýza DNA MeSH
• polymerázová řetězová reakce metody   MeSH
• poškození DNA genetika   MeSH
• proteiny buněčného cyklu genetika   MeSH
• sekvence nukleotidů MeSH
• senzitivita a specificita MeSH
• syndrom MeSH
• tolerance záření genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Československo MeSH
• Německo MeSH
• Názvy látek
• DNA primery MeSH
• jaderné proteiny MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH

Patients with Nijmegen Breakage Syndrome (NBS) have a high risk to develop malignant diseases, most frequently B-cell lymphomas. It has been demonstrated that this chromosomal breakage syndrome results from mutations in the NBS1 gene that cause either a loss of full-length protein expression or expression of a variant protein. A large proportion of the known NBS patients are of Slavic origin who carry a major founder mutation 657del5 in exon 6 of the NBS1 gene. The prevalence of this mutation in Slav populations is reported to be high, possibly contributing to higher cancer risk in these populations. Therefore, if mutations in NBS1 are associated with higher risk of developing lymphoid cancers it would be most likely to be observed in these populations. A multiplex assay for four of the most frequent NBS1 mutations was designed and a series of 119 lymphoma patients from Slavic origin as well as 177 healthy controls were tested. One of the patients was a heterozygote carrier of the ACAAA deletion mutation in exon 6 (1/119). No mutation was observed in the control group, despite the reported high frequency (1/177). The power of this study was 30% to detect a relative risk of 2.0.

• MeSH
• běloši MeSH
• chromozomální nestabilita genetika   MeSH
• genetické testování MeSH
• Hodgkinova nemoc genetika   MeSH
• jaderné proteiny genetika   MeSH
• lidé MeSH
• mutace MeSH
• nehodgkinský lymfom genetika   MeSH
• polymerázová řetězová reakce MeSH
• proteiny buněčného cyklu genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• jaderné proteiny MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH

BACKGROUND INFORMATION: The DNA damage response is a fundamental, well-regulated process that occurs in the genome to recognise DNA lesions. Here, we studied kinetics of proteins involved in DNA repair pathways and their recruitment to DNA lesions during the cell cycle. In non-irradiated and irradiated cells, we analysed the distribution pattern and spatiotemporal dynamics of γH2AX, 53BP1, BMI1, MDC1, NBS1, PCNA, coilin and BRCA1 proteins. RESULTS: We observed that spontaneous and irradiation-induced foci (IRIF) demonstrated a high abundance of phosphorylated H2AX, which was consistent with 53BP1 and BMI1 protein accumulation. However, NBS1 and MDC1 proteins were recruited to nuclear bodies (NBs) to a lesser extent. Irradiation by γ-rays significantly increased the number of 53BP1- and γH2AX-positive IRIF, but cell cycle-dependent differences were only observed for γH2AX-positive foci in both non-irradiated and γ-irradiated cells. In non-irradiated cells, the G2 phase was characterised by an increased number of spontaneous γH2AX-foci; this increase was more pronounced after γ-irradiation. Cells in G2 phase had the highest number of γH2AX-positive foci. Similarly, γ-irradiation increased the number of NBS1-positive NBs only in G2 phase. Moreover, NBS1 accumulated in nucleoli after γ-irradiation showed the slowest recovery after photobleaching. Analysis of protein accumulation kinetics at locally induced DNA lesions showed that in HeLa cells, BMI1, PCNA and coilin were rapidly recruited to the lesions, 10-15 s after UVA-irradiation, whereas among the other proteins studied, BRCA1 demonstrated the slowest recruitment: BRCA1 appeared at the lesion 20 min after local micro-irradiation by UVA laser. CONCLUSION: We show that the kinetics of the accumulation of selected DNA repair-related proteins is protein specific at locally induced DNA lesions, and that the formation of γH2AX- and NBS1-positive foci, but not 53BP1-positive NBs, is cell cycle dependent in HeLa cells. Moreover, γH2AX is the most striking protein present not only at DNA lesions, but also spreading out in their vicinity. SIGNIFICANCE: Our conclusions highlight the significant role of the spatiotemporal dynamics of DNA repair-related proteins and their specific assembly/disassembly at DNA lesions, which can be cell type- and cell cycle dependent.

• Klíčová slova
• Cell cycle, DNA repair, Interphase, Living cell studies, Micro-irradiation, γ-Irradiation,
• MeSH
• 53BP1 MeSH
• buněčný cyklus genetika   účinky záření   MeSH
• DNA genetika   metabolismus   MeSH
• fosforylace účinky záření   MeSH
• HeLa buňky MeSH
• histony genetika   metabolismus   MeSH
• intracelulární signální peptidy a proteiny genetika   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• lidé MeSH
• oprava DNA genetika   účinky záření   MeSH
• poškození DNA genetika   účinky záření   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• ultrafialové záření MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 53BP1 MeSH
• DNA MeSH
• H2AX protein, human MeSH Prohlížeč
• histony MeSH
• intracelulární signální peptidy a proteiny MeSH
• jaderné proteiny MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH
• TP53BP1 protein, human MeSH Prohlížeč

DNA damage response (DDR) in ribosomal genes and mechanisms of DNA repair in embryonic stem cells (ESCs) are less explored nuclear events. DDR in ESCs should be unique due to their high proliferation rate, expression of pluripotency factors, and specific chromatin signature. Given short population doubling time and fast progress through G1 phase, ESCs require a sustained production of rRNA, which leads to the formation of large and prominent nucleoli. Although transcription of rRNA in the nucleolus is relatively well understood, little is known about DDR in this nuclear compartment. Here, we directed formation of double-strand breaks in rRNA genes with I- PpoI endonuclease, and we studied nucleolar morphology, DDR, and chromatin modifications. We observed a pronounced formation of I- PpoI-induced nucleolar caps, positive on BRCA1, NBS1, MDC1, γH2AX, and UBF1 proteins. We showed interaction of nucleolar protein TCOF1 with HDAC1 and TCOF1 with CARM1 after DNA injury. Moreover, H3R17me2a modification mediated by CARM1 was found in I- PpoI-induced nucleolar caps. Finally, we report that heterochromatin protein 1 is not involved in DNA repair of nucleolar caps.

• Klíčová slova
• CARM1, DNA repair, HDAC1, NBS1, PpoI, chromatin, nucleolus,
• MeSH
• acetylace MeSH
• arginin metabolismus   MeSH
• buněčné jadérko genetika   ultrastruktura   MeSH
• buněčné linie MeSH
• dvouřetězcové zlomy DNA * MeSH
• embryonální kmenové buňky metabolismus   ultrastruktura   MeSH
• fosfoproteiny metabolismus   MeSH
• geny rRNA MeSH
• histondeacetylasa 1 metabolismus   MeSH
• histony metabolismus   MeSH
• intracelulární signální peptidy a proteiny MeSH
• jaderné proteiny metabolismus   MeSH
• metylace MeSH
• myši MeSH
• oprava DNA MeSH
• proteinarginin-N-methyltransferasy metabolismus   MeSH
• RNA ribozomální genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• arginin MeSH
• coactivator-associated arginine methyltransferase 1 MeSH Prohlížeč
• fosfoproteiny MeSH
• Hdac1 protein, mouse MeSH Prohlížeč
• histondeacetylasa 1 MeSH
• histony MeSH
• intracelulární signální peptidy a proteiny MeSH
• jaderné proteiny MeSH
• proteinarginin-N-methyltransferasy MeSH
• RNA ribozomální MeSH
• Tcof1 protein, mouse MeSH Prohlížeč

Nijmegen breakage syndrome (NBS) is a chromosomal instability disorder, clinically characterised by microcephaly, immunodeficiency, radiosensitivity and a very high predisposition to lymphoid malignancy. Recently, it was demonstrated that mutations in the NBS1 gene are responsible for NBS. Most of the NBS patients known so far are of Slav origin and carry a major founder mutation 657del5 in exon 6 of the NBS1 gene. In this study we estimated the prevalence of the 657del5 mutation in the Czech Republic, Poland and the Ukraine. We found an unexpectedly high carrier frequency of the 657del5 mutation (1/177) in the three Slav populations, a factor that may contribute to cancer frequency in those countries. In addition, we show that NBS patients are often diagnosed late and therefore receive inappropriate therapy.

• MeSH
• chromozomální aberace * MeSH
• frekvence genu MeSH
• genetické testování MeSH
• heterozygot MeSH
• lidé MeSH
• mikrocefalie MeSH
• mnohočetné abnormality epidemiologie   genetika   patologie   MeSH
• mutace * MeSH
• novorozenec MeSH
• prevalence MeSH
• sekvenční delece MeSH
• syndrom MeSH
• těžká kombinovaná imunodeficience MeSH
• Check Tag
• lidé MeSH
• novorozenec MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Polsko MeSH
• Ukrajina MeSH

BACKGROUND: Nijmegen breakage syndrome (NBS) is an autosomal recessive chromosomal instability disorder with hypersensitivity to ionising radiation. The clinical phenotype is characterised by congenital microcephaly, mild dysmorphic facial appearance, growth retardation, immunodeficiency, and greatly increased risk for lymphoreticular malignancy. Most NBS patients are of Slavic origin and homozygous for the founder mutation 657del5. The frequency of 657del5 heterozygotes in the Czech population is 1:150. Recently, another NBS1 mutation, 643C>T(R215W), with uncertain pathogenicity was found to have higher frequency among tumour patients of Slavic origin than in controls. This alteration results in the substitution of the basic amino acid arginine with the non-polar tryptophan and thus could potentially interfere with the function of the NBS1 protein, nibrin. METHODS AND RESULTS: Children with congenital microcephaly are routinely tested for the 657del5 mutation in the Czech and Slovak Republics. Here, we describe for the first time a severe form of NBS without chromosomal instability in monozygotic twin brothers with profound congenital microcephaly and developmental delay who are compound heterozygotes for the 657del5 and 643C>T(R215W) NBS1 mutations. Both children showed reduced expression of full length nibrin when compared with a control and a heterozygote for the 657del5 mutation. Radiation response processes such as phosphorylation of ATM and phosphorylation/stabilisation of p53, which are promoted by NBS1, are strongly reduced in cells from these patients. CONCLUSIONS: Interestingly, the patients are more severely affected than classical NBS patients. Consequently, we postulate that homozygosity for the 643C>T(R215W) mutation will also lead to a, possibly very, severe disease phenotype.

• MeSH
• chromozomální nestabilita MeSH
• fosforylace MeSH
• geny recesivní MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• lidé MeSH
• mapování chromozomů * MeSH
• mikrocefalie genetika   MeSH
• mutace * MeSH
• nemoci u dvojčat MeSH
• polymerázová řetězová reakce MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• substituce aminokyselin MeSH
• syndrom Nijmegen breakage genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• jaderné proteiny MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH