Ataxia-telangiectasia: una revisión desde la etiopatogenia al manejo actual con descripción de casos reportados en Perú / Ataxia telangiectasia: A review from etiopathogenesis to current management with a description of reported cases in Peru

La Ataxia-Telangiectasia (AT) es una rara enfermedad de herencia autosómica recesiva y de afección multisistémica, caracterizada por ataxia progresiva, inmunodeficiencia variable con infecciones recurrentes, riesgo incrementado de neoplasias con o sin telangiectasias óculo-cutáneas. La AT es causada por variantes patogénicas bialélicas en el gen ATM. Su diagnóstico se basa en la sospecha de un cuadro clínico compatible, niveles elevados de alfafetoproteína, atrofia cerebelosa y estudios genéticos. No existe tratamiento curativo de AT y su manejo se basa en medidas de soporte y prevención de complicaciones y asesoramiento genético. En esta revisión, actualizamos la epidemiología, manifestaciones clínicas, diagnóstico y tratamiento de AT incluyendo una búsqueda de casos publicados en el Perú.

Ataxia-Telangiectasia (AT) is a rare autosomal recessive disease with multisystemic involvement, characterized by slowly progressive ataxia, variable immunodeficiency with recurrent infections, increased risk of neoplasms with or without oculocutaneous telangiectasias. AT is caused by biallelic pathogenic variants within the ATM gene. Its diagnosis is based on suspicion of a compatible clinical symptomatology, increased levels of alpha-fetoprotein, cerebellar atrophy, and genetic testing. There is no curative treatment for AT and its management is based on supportive and preventive measures of eventual complications and genetic counseling. This review updates the epidemiology, clinical manifestations, diagnosis, and treatment of AT, including a search for cases published in Peru.

Expression and functional SNP loci screen of ATM from coal worker's pneumoconiosis / 中华劳动卫生职业病杂志

Objective: To detect of gene expression and genotype of the ataxia telangiectasia mutated (ATM) from coal workers' pneumoconiosis (CWP) , It is explored whether CWP is related to ATM gene. Methods: In October 2020, the relevant information of 264 subjects who received physical examination or medical treatment in the Department of occupational diseases of Guiyang public health treatment center from January 2019 to September 2020 was collected. Through the occupational health examination, 67 healthy people with no history of exposure to occupational hazards were selected as the healthy control group; The coal miners with more than 10 years of coal dust exposure history and small shadow in the lung but not up to the diagnostic criteria were the dust exposure control group, a total of 66 people; The patients with the same history of coal dust exposure and confirmed stage I were coal worker's pneumoconiosis stage I group, a total of 131 people. The expression of ATM was detected by QRT PCR. ATM rs189037 and rs1801516 were genotyped by massarray. Results: There was significant difference in the expression of ATM among the groups (P<0.05) ; Compared with the healthy control group, the expression of ATM in the dust exposed control group was significantly increased (P<0.05) . With the occurrence and development of CWP, the GG of rs189037 wild type decreased, the GA of mutant heterozygote and AA of homozygote increased, but the difference was not statistically significant (P>0.05) ; Rs1801516 wild type GG and mutant heterozygote GA had no significant changes (P>0.05) . There were significant differences in age, neutrophils and basophils among rs189037 groups (all P<0.05) . There were no significant differences in blood pressure, eosinophils, lymphocytes, monocytes, smoking and drinking history among rs189037 groups (all P>0.05) . Compared with wild-type GG, the or of mutant heterozygotes and homozygotes increased, but the differences were not statistically significant (P>0.05) . Conclusion: ATM gene may be one of the early activation genes of CWP and rs189037 may be the functional loci which affects gene expression. ATM gene is related to inflammatory response, Neutrophils and basophils have an impact on the development of CWP.

Siblings Seckel's syndrome 1 caused by ATR gene variants in a sibpair / 中华医学遗传学杂志

OBJECTIVE@#Two brothes with Seckel's syndrome 1(SCKL1) were reported and a literature review was carried to provide clinical and genetic information of this rare disease.@*METHODS@#Clinical data of the two children were collected, and the peripheral blood was extracted for whole exome sequencing. Literature of the disease were reviewed.@*RESULTS@#The two patients were 11 years and 9.5 years old when examined for short stature. They presented with intrauterine growth retardation, intellectual disability, microcephaly, birdhead-like face and coffee au lait spots. The bone age was more than 2 years behind the chronical age and the growth hormone levels were normal. Whole exome sequencing revealed novel compound heterozygous variants c.1A>G (p.M1?) and c.4853-18A>G of ART gene in both children.@*CONCLUSION@#Children with prenatal onset short stature, developmental delay, microcephaly and special facial featuresshould be considered for the possibility of Seckel's syndrome, whole exome sequencing could help to confirm the clinical diagnosis.

Differential molecular signature of human saliva using atr-ftir spectroscopy for chronic kidney disease diagnosis

Abstract The symptoms of chronic kidney disease (CKD) are often not specific or absent in the early stages of this illness. Therefore, there is a demand for developing low cost, non-invasive and highly accurate platforms for CKD diagnostics. We hypothesized that the level of specifics salivary components changes when CKD is emplace, which could be clinically used to discriminate CKD patients from healthy subjects. The present study aimed to compare salivary components between CKD patients and matched control subjects by using attenuated total reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The predictive power of salivary components was evaluated by receiver operating characteristic (ROC) curves. Several components were identified, and 4 of them showed different expression (p<0.05) between CKD and control subjects. Thiocyanate (SCN-, 2052 cm-1) and phospholipids/carbohydrates (924 cm-1) vibrational modes using original and second-derivative spectra by ATR-FTIR could potentially be used as salivary biomarkers to differentiate CKD than control subjects. The combination of original and second-derivative spectra by ATR-FTIR of 924 cm-1 vibrational modes could reach 92.8% sensitivity and 85.7% specificity for CKD detection. Despite, the limitation of our investigation, the acquired data indicates that salivary vibrational modes by ATR-FTIR platform should be further explored as an auxiliary diagnostic tool for CKD.

Resumo Os sintomas da doença renal crônica (DRC) são frequentemente inespecíficos ou ausentes nos estágios iniciais desta doença. Desta forma, existe uma demanda para o desenvolvimento de plataformas com baixo custo, não-invasivas e com alta acurácia para o diagnóstico da DRC. Nós hipotetizamos que o nível dos componentes salivares se alteram pela DRC, o que pode ser clinicamente utilizado para discriminar pacientes portadores de DRC de indivíduos controles. O objetivo deste estudo foi comparar componentes salivares entre pacientes portadores de DRC e sujeitos controles utilizando um sistema de reflectância total atenuada com espectroscopia infravermelho com transformada em Fourier (ATR-FTIR). O poder preditivo dos componentes salivares foi avaliado pela curva característica de operação do receptor (ROC). Diversos componentes salivares foram identificados e 4 destes apresentaram diferença na expressão (p<0,05) entre DRC e sujeitos controles. O modos vibracionais do tiocianato (2052 cm-1) e de fosfolipídeos/carbohidratos (924 cm-1) utilizando espectros originais e da segunda-derivada pelo ATR-FTIR podem potencialmente ser utilizados como biomarcadores salivares para discriminar a DRC de sujeitos controles. A combinação dos espectros originais e da segunda-derivada pelo ATR-FTIR do modo vibracional 924 cm-1 pode apresentar sensibilidade de 92.8% e especificidade de 85.7% para a detecção da DRC. Este estudo indicou que modos vibracionais da saliva pela plataforma ATR-FTIR podem ser uma ferramenta auxiliar no diagnóstico da DRC.

Topoisomerase inhibitor upregulates MICA/B expression in breast cancer cells through ATM/ATR and NF-κB pathway / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effects of chemotherapeutic agents widely used in clinical practice on major histocompatibility complex class I-related chain A and B (MICA/B) expression in breast cancer cells, and to explore the molecular mechanisms involved.@*METHODS@#We examined MICA/B mRNA and surface protein expressions in breast cancer cells treated with chemotherapeutic agents by real-time RT-PCR and flow cytometry respectively. The blocking effects of ataxia telangiectasia mutated and Rad3-related kinase (ATM/ATR) inhibitor caffeine and nuclear factor κB (NF-κB) inhibitor pynolidine dithiocarbamate (PDTC) on etoposide-upregulated MICA/B mRNA and surface protein expressions were investigated. Electrophoretic mobility shift assay (EMSA) was taken to investigate whether etoposide enhanced the binding of NF-κB to MICA/B gene promoter.@*RESULTS@#Three topoisomerase inhibitors etoposide, camptothecin and doxorubicine upregulated MICA and MICB mRNA expressions in breast cancer cell MCF-7. Comparing to no-drug-treated cells, MICA mRNA levels increased to (1.68±0.17), (2.54±0.25) and (3.42±0.15) fold, and levels of MICB mRNA increased to (1.82±0.24), (1.56±0.05) and (5.84±0.57) fold respectively in cancer cells treated by etoposide at the concentrations of 5, 20 and 100 μmol/L (P<0.05). MICA and MICB mRNA levels also increased significantly when MCF-7 cells were incubated with camptothecin or doxorubicine at the specific concentrations (P<0.05). MICB mRNA expression also increased slightly in another breast cancer cell SK-BR-3 treated by topoisomerase II inhibitors etoposide and camptothecin (P<0.05). Furthermore, etoposide and camptothecin upregulated MICA/B surface protein expression in MCF-7 cells (P<0.05), and the upregulation was found in both living and apoptotic cells. Our study showed that etoposide induced-MICA/B expression in MCF-7 was inhibited by caffeine at different concentrations. When cancer cells were treated by caffeine with 1, 5 and 10 mmol/L, MICA mRNA levels decreased from (3.75±0.25) to (0.89±0.05), (0.81±0.02) and (0.48±0.04) fold respectively (P<0.001), and MICB mRNA levels decreased from (6.85±0.35) to (1.36±0.13), (0.76±0.06) and (0.56±0.03) fold (P<0.05), while MICA/B protein levels decreased from (3.42±0.05) to (1.32±0.03), (1.21±0.06) and (1.14±0.03) fold (P<0.001), indicating that etoposide-induced MICA/B expression was inhibited by ATM/ATR inhibitor. Similarly, NF-κB inhibitor PDTC also inhibited MICA/B mRNA and protein expressions induced by etoposide significantly when MCF-7 cells were incubated with PDTC at the concentrations of 10, 50 and 100 μmol/L (P<0.05), indicating that NF-κB was also involved in this process. EMSA showed that the binding of NF-κB to MICA/B promoter enhanced in MCF-7 cells after etoposide treatment.@*CONCLUSION@#Topoisomerase inhibitor increased MICA/B mRNA and protein expressions in breast cancer cells, indicating that chemotherapeutic agents might increase the recognizing and killing ability of immunocytes to breast cancer cells. ATM/ATR and NF-κB pathways might be involved in it.

Nueva mutación en el gen ATM en paciente con ataxis telangiectasia: Caso clínico / New mutation in ATM gen in patient whith Ataxia Telangiectasia: Clinical case

Introducción: El síndrome de ataxia telangiectasia (AT) es una enfermedad genética autosómica recesiva de compromiso multisistémico, con un espectro clínico amplio, ocasionada por la mutación del gen ATM, lo que causa la disminución o ausencia de la proteinkinasa ATM, por lo que se alteran procesos del ciclo celular, reparación del ADN y apoptosis. El objetivo de este artículo es el de reportar el caso de una paciente con síndrome de AT causada por una mutación no reportada previamente en la literatura. Caso clínico: Paciente originaria de Colombia, de 14 años de edad, con manifestaciones clínicas y fenotípicas clásicas del síndrome de AT a partir de los 6 años de edad, con alteración pondoestatural, infecciones respiratorias a repetición, telangiectasias oculocutáneas y compromiso neurológico progresivo, caracterizado por regresión en su desarrollo psicomotor, ataxia y apraxia oculomotora. Se realizó secuenciación del gen ATM que demostró mutación en homocigosis no reportada previamente en la literatura. Discusión: En Latinoamérica son escasos los reportes de pacientes con AT y pocos aquellos en donde se describen los hallazgos moleculares. Los estudios moleculares son una herramienta que facilita el diagnóstico y permite orientar mejor el manejo y pronóstico de pacientes con enfermedades neurodegenerativas. El reporte de variantes moleculares no descritas es de gran importancia para establecer la causa etiológica de este tipo de patologías en grupos poblacionales diversos, como lo son los países de Latinoamérica.

Introduction: The ataxia telangiectasia syndrome (AT) is a genetic disease with an autosomal recessive inheritance pattern, with multisystem involvement and a broad clinical spectrum. It is caused by the mutation of the ATM gene, causing reduction or absence of the ATM proteinkinase, altering processes in the cell cycle, DNA repair and apoptosis. The objective of this article is to report the case of a patient with ataxia telangiectasia syndrome, caused by a mutation not previously reported in the literature. Case report: A 14 year-old patient native to Colombia, with classic clinical and phenotypical manifestations of AT syndrome, which started at 6 years of age with pondostatural alteration, recurrent respiratory infections, oculocutaneus telangiectasias and progressive neurological disorder that included: regression in her psychomotor development, ataxia and oculomotor apraxia. ATM gene sequencing is performed evidencing a homozygous mutation not reported in literature. Discussion: In Latin America are sparse the number of reports of patients with ataxia telangiectasia and only few of these describe their molecular findings. Molecular studies allow the diagnosis and a better orientation in the management and prognosis of patients with neurodegenerative diseases. The report of undescribed molecular variants is of great importance to establish the etiology of such diseases in diverse population groups, such as the countries of Latin America.

MiR-181a Promotes Proliferation of Human Acute Myeloid Leukemia Cells by Targeting ATM / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate miR-181a function and regulation mechanism by identifying miR-181a target genes in acute myeloid leukemia (AML).</p><p><b>METHODS</b>The HL-60 cells of human AML was transfected by small molecular analog miR-181a, the cell proliferation was detected by CCK-8 method after electroporation in HL-60 cell lines. Target genes of miR-181a were predicted and analyzed by the bioinformatics software and database. Target genes were confirmed by HL-60 cell line and the patient leukemia cells.</p><p><b>RESULTS</b>Overexpressed miR-181a in HL-60 cell line significantly enhanced cell proliferation compared with that in control (P < 0.05). Dual luciferase reporter gene assay showed that miR-181a significantly suppressed the reporter gene activity containing ATM 3'-UTR by about 56.8% (P < 0.05), but it didn't suppress the reporter gene activity containing 3'-UTR ATM mutation. Western blot showed that miR-181a significantly downregulated the expression of ATM in human leukemia cells. It is also found that miR-181a was significantly increased in AML, which showed a negative correlation with ATM expression.</p><p><b>CONCLUSION</b>miR-181a promotes cell proliferation in AML by regulating the tumor suppressor ATM, thus it plays the role as oncogene in pathogenesis of AML.</p>

Delayed DNA double-strand break in S-phase H1299 cells after thermal damage / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the pattern of DNA double-strand break (DSB) formation in S-phase cells after thermal damage and explore the mechanisms behind heat sensitivity of S-phase cells and delayed DSBs.</p><p><b>METHODS</b>Flow cytometry was used to analyze the cell cycle arrest in H1299 cells exposed to thermal damage, and EdU incorporation assay was employed to evaluate the DNA replication capacity of the cells. The cells synchronized in S phase were obtained by serum starvation and DSBs were observed dynamically using neutral comet assay. Trypan blue dye exclusion technique was used to analyze the cell viability after thermal damage. Western blotting (WB) was used to detect the phosphorylation of ATM and DNA binding RAD18.</p><p><b>RESULTS</b>The percentage of S-phase cells increased significantly after exposure of the cells to 45 degrees celsius; for 1 h (P<0.01). The time-dependent variation pattern of EdU incorporation was similar to that of S-phase cell fraction. The comet tail began to appear only after incubation of the cells at 37 degrees celsius; for some time and the Olive tail moment (OTM) increased with prolonged incubation. Cell death remained low until 7.5 h after heat exposure of the S-phase cells and then increased rapidly. The phosphorylation of ATM first increased but then decreased drastically. In cells with heat exposure, DNA binding RAD18 was attenuated obviously compared that in non-exposed cells.</p><p><b>CONCLUSION</b>Thermal damage causes cell cycle arrest in S phase, and delayed fatal DSBs occur in the arrested cells due to persistent replication and DNA damage repair suppression, which are the possible cause of heat sensitivity of S-phase cells.</p>

Expressions of SMG-1, ATM and P53 in laryngeal squamous cell carcinoma and their clinical significance / 南方医科大学学报

<p><b>OBJECTIVE</b>To detect the expression of SMG-1, ATM and P53 in laryngeal squamous cell carcinoma (LSCC) and their correlation with the clinicopathological features and outcomes of the patients.</p><p><b>METHODS</b>Sixty-three specimens of surgically resected LSCC tissues and 30 specimens of adjacent normal tissue were examined for the expressions of ATM, SMG-1 and P53 using immunohistochemistry. The correlation of ATM, SMG-1 and P53 expressions with the clinicopathological factors and their interactions were analyzed.</p><p><b>RESULTS</b>The positive expression rates of SMG-1, ATM and P53 in LSCC were 36.5% (23/63) , 41.3% (26/63) and 57.1% (36/63) respectively, significantly different from those in the adjacent tissue (73.3%, 83.3% and 20.0%, respectively; P<0.05). The expression of SMG-1 in LSCC was positively correlated with the pathological grade and T stage of the tumors (P<0.05), and ATM and P53 were not related to the clinicopathological factors (P>0.05). The 5-year survival rate of patients negative for SMG-1 expression was significantly higher than that of SMG-1-positive patients (P<0.05). The expression of SMG-1 was negatively correlated with that of P53 (r=-0.476, P<0.01).</p><p><b>CONCLUSION</b>SMG-1, ATM and P53 are closely related to the occurrence of LSCC. SMG-1 expression is an important factor associated with the clinicopathological features and prognosis of LSCC patients, and may play an important role in the development of LSCC by regulating P53 expression.</p>

Advances of Research on Ataxia Telangiectasia Mutated Gene and Risk Factors of Cardiovascular Disease / 生物医学工程学杂志

Cardiovascular disease is a severe threat to human health and life. Among many risk factors of cardiovascular disease, genetic or gene-based ones are drawing more and more attention in recent years. Accumulated evidence has demonstrated that the loss or mutation of ataxia telangiectasia mutated (ATM) gene can result in DNA damage repair dysfunctions, telomere shortening, decreased antioxidant capacity, insulin resistance, increased lipid levels, etc., and thus can promote the occurrence of cardiovascular risk factors, such as aging, atherosclerosis and metabolic syndrome. In this review, we discusses the possible mechanisms between ATM gene and cardiovascular risk factors, which could be helpful to the related research and clinical application.

Estudo dos mecanismos moleculares do reparo de quebra de duplas fitas no DNA mitocondrial / Study of the molecular mechanisms of double-strand break repair in mitochondrial DNA

O DNA está constantemente exposto a danos causados tanto por agentes endógenos quanto exógenos. Estes podem causar diferentes tipos de lesões incluindo modificações de bases e do açúcar, além de quebras de fitas simples ou duplas. As quebras de duplas fitas, quando comparadas às demais, constituem as mais citotóxicas e podem resultar em deleções no DNA e instabilidade genética. Deleções no DNA mitocondrial (mtDNA) causam diversas doenças e estão envolvidas no processo de envelhecimento. No núcleo, as quebras de duplas fitas no DNA podem ser reparadas por recombinação homóloga (HR), ligação de pontas não homólogas (NHEJ) e anelamento de fita simples (SSA). No entanto, em mitocôndrias de células de mamíferos, o reparo de quebras de duplas fitas ainda não foi completamente caracterizado. Experimentos in vitro usando extratos mitocondriais de células de roedores mostraram que estes são capazes de reparar essas quebras, no entanto pouco é sabido sobre quais proteínas são responsáveis por cada etapa de reparo, bem como sua implicação na manutenção da integridade do genoma mitocondrial. Sendo assim, nesse trabalho investigamos a localização e função mitocondrial das proteínas ATM, Rad51, Rad52, Ku70/86 e DNA-PKCs, que são sabidamente envolvidas em reparo de quebras de duplas fitas no núcleo. Para identificar essas proteínas em mitocôndrias de células de mamíferos, mitocôndrias foram isoladas a partir de células da linhagem HEK293T, usando centrifugação diferencial seguida por gradiente de Percoll. Para as proteínas de recombinação homóloga, ATM e Rad51, imunodetectamos isoformas semelhantes em todos os compartimentos celulares. Já para a proteína Rad52 o mesmo anticorpo imunodetectou duas bandas distintas na mitocôndria ao passo que no núcleo foram quatro. Além disso, verificamos que baixos níveis de proteína Rad52, induzidos pela expressão de shRNA (short hairping RNA) específico, resultam em diminuição do número de cópias de mtDNA bem como acúmulo de deleções no genoma mitocondrial. Para as proteínas de NHEJ, DNA-PKCs e a subunidade Ku70, identificamos isoformas semelhantes em todos os compartimentos celulares. Já para a subunidade 86 do heterodímero Ku70/86 o anticorpo detectou, somente em mitocôndrias, uma banda menor de 50 kDa, a qual difere na região N-terminal da subunidade detectada no núcleo (86 KDa). Experimentos de co-imunprecitação de proteínas mostraram que essa isoforma menor compõe o heterodímero mitocondrial juntamente com a subunidade 70 (mtKu70/50) e que esse interage com DNA ligase III mitocondrial. Nossos resultados também mostraram que a estabilidade proteica de mtKu70/50 é regulada por ATM. Tratamento das células com peróxido de hidrogênio, que induz quebras de duplas fitas, aumentou a associação do heterodímero mtKu70/50 com o mtDNA, de forma independente de aumento da concentração proteica intra-mitocondrial. Já a diminuição dos níveis proteicos de Ku, induzida através de shRNA, resultou em diminuição do número de cópias de mtDNA e acumulo de danos nesse genoma. Extratos mitocondriais de células knockdown para Ku apresentaram menor atividade de reparo NHEJ em um ensaio in vitro, sugerindo que o acúmulo de danos nestas células é provavelmente devido a deficiências na via de NHEJ. Em conjunto, nossos dados sugerem que tanto HR quanto NHEJ operam em mitocôndrias. Além disso, a via de NHEJ mitocondrial utiliza o heterodímero mitocondrial Ku70/50 o qual está envolvido na manutenção do mtDNA. Ademais, nossos resultados mostram uma grande conservação molecular e funcional entre as vias de reparo de NHEJ e HR no núcleo e na mitocôndria, o que reforça sua importância para a manutenção da estabilidade genômica mitocondrial e, provavelmente a função mitocondrial

DNA is constantly exposed to damaging agents from both endogenous and exogenous sources. These can cause different types of DNA lesions that include base and sugar modifications and single and double strand breaks. DNA doublestrand breaks (DSBs) are among the most cytotoxic DNA lesions, which can result in deletions and genetic instability. Deletions in the mitochondrial DNA (mtDNA) cause numerous human diseases and drive normal aging. DSBs in the nuclear DNA are repaired by non-homologous DNA end joining (NHEJ), homologous recombination (HR) or Single Strand Annealing (SSA). Yet, repair of DSBs in mammalian mitochondria has not been fully characterized. Mitochondrial extracts from rodent cells are proficient in ligating DNA ends in vitro, but little is known about which proteins are responsible for each enzymatic step and its implication in mitochondrial genome maintenance. Thus, we investigated mitochondrial localization and function of DSBR (double strand break repair) proteins ATM, Rad51, Rad52, the Ku70/86 heterodimer and DNA-PKCs.To identify DSBR proteins in mammalian mitochondria, highly purified mitochondria from HEK293T cells were isolated using differential centrifugation followed by Percoll gradient. For HR proteins, we detected similar isoforms for ATM and Rad51 proteins in all cellular compartments. Two mitochondriaspecific isoforms of Rad52 were detected, while the same antibody detected four isoforms in the nucleus. In addition, lower Rad52 protein levels, induced by specific shRNA expression, result in decreased mtDNA copy number and accumulation of deleted mitochondrial genomes. For NHEJ proteins, similar isoforms of DNA-PKcs and the Ku70 subunit were detected in all cellular compartments. On the other hand, antibodies against the Ku86 subunit detected a smaller band in mitochondrial extracts (50 KDa), lacking the N-terminal region of the canonical isoform detected in the nucleus (86 KDa). The mitochondrial Ku70/50 heterodimer interacts with mitochondrial DNA ligase III, suggesting a role in DSBR. Moreover, stability of the mtKu heterodimer is regulated by ATM. Hydrogen peroxide treatment, which induces DSBs, increases mtKu70/50 association with the mtDNA and cells with reduced Ku levels, also induced by shRNA transfection, have lower mtDNA copy number and accumulate mtDNA damage. Moreover, mitochondrial extracts from Ku knockdown cells show lower NHEJ repair activity in an in vitro assay, suggesting that damage accumulation in these cells is likely due to deficiencies in NHEJ. Together, our data suggest that both HR and NHEJ operate in mitochondria. Also, mtNHEJ requires the Ku heterodimer and is involved in mtDNA maintenance. Moreover, our results indicate that there is a significant molecular and functional conservation between NHEJ and HR repair pathways in the nucleus and in mitochondria, which reinforces their importance for maintenance of mitochondrial genomic stability and, likely mitochondrial function

ATM polymorphisms IVS24-9delT, IVS38-8T>C, and 5557G>A in Mexican women with familial and/or early-onset breast cancer / Polimorfismos IVS24-9delT, IVS38-8T>C y 5557G>A en el gen ATM en mujeres mexicanas con cáncer de mama familiar o de inicio temprano

Objective. To assess whether in Mexican population the frequencies of ATM polymorphisms IVS24-9delT, IVS38-8-T>C, and 5557G>A in breast cancer (BC) cases and healthy controls were different from those found in other countries. Materials and methods. Frequencies of polymorphisms conferring BC risk IVS24-9delT, IVS38-8T>C, and 5557G>A were analyzed by PCR-RFLP in 94 patients with familial and/or early onset BC, and 97 healthy controls randomly selected. Allele frequencies analysis was done using χ² and Hardy-Weinberg test. Results. Frequencies of heterozygous were: for 5557G>A, 13% cases, 0%controls (p=0.0009); for IVS24-9delT, 21% cases, 8% controls (p=0.0122); for IVS38-8T>C, only one case. 5557G>A and IVS24-9delT were more frequent in cases than in controls. The allelic frequencies found in 5557G>A are similar to those described by González-Hormazábal in Chile. Conclusion. The similarity of results in this polymorphism between Chilean and Mexican populations may be due to both being crossbred with an Amerindian-Spanish component, while differences may be due to fact that Chilean population has a greater European component than Mexican's.

Objetivo. Evaluar si en la población mexicana las frecuencias de los polimorfismos IVS-9delT, IVS38-8T>C y 5557G>A en casos de cáncer de mama y en controles sanos son diferentes de las encontradas en otros países. Material y métodos. Los polimorfismos IVS24-9delT, IVS38-8T>C y 5557G>A fueron analizados mediante PCR-RFLPs en 94 pacientes con CM de tipo familiar o de inicio temprano y 97 testigos seleccionadas de forma aleatoria. El análisis de la frecuencia alélica se hizo mediante χ² y equilibrio de Hardy-Weinberg. Resultados. Las frecuencias de heterocigotos fueron 5557G>A, 13% de casos, 0% de testigos (p=0.0009); IVS24-9delT, 21% de casos, 8% de testigos (p=0.0l22); IVS38-8T>C, sólo un caso. 5557G>A y IVS24-9delT fueron más frecuentes en casos que en testigos. Las frecuencias alélicas encontradas en 5557G>A son similares a las descritas por González-Hormazábal en Chile. Conclusión. La similitud de resultados en este polimorfismo entre la población chilena y mexicana puede ser debida a que ambas son mestizas con un componente amerindio-español. Las diferencias encontradas podrían explicarse porque la población chilena tiene mayor componente europeo que la mexicana.

Gadd45a deletion aggravates hematopoietic stem cell dysfunction in ATM-deficient mice

Ataxia telangiectasia mutated (ATM) kinase plays an essential role in the maintenance of genomic stability. ATM-deficient (ATM(-/-)) mice exhibit hematopoietic stem cell (HSC) dysfunction and a high incidence of lymphoma. Gadd45a controls cell cycle arrest, apoptosis and DNA repair, and is involved in the ATM-p53 mediated DNA damage response. However, the role of Gadd45a in regulating the functionality of ATM(-/-) HSCs is unknown. Here we report that Gadd45a deletion did not rescue the defects of T-cells and B-cells development in ATM(-/-) mice. Instead, ATM and Gadd45a double knockout (ATM(-/-) Gadd45a(-/-)) HSCs exhibited an aggravated defect in long-term self-renewal capacity compared to ATM(-/-) HSCs in HSC transplantation experiments. Further experiments revealed that the aggravated defect of ATM(-/-) Gadd45a(-/-) HSCs was due to a reduction of cell proliferation, associated with an accumulation of DNA damage and subsequent activation of DNA damage response including an up-regulation of p53-p21 signaling pathway. Additionally, ATM(-/-) Gadd45a(-/-) mice showed an increased incidence of hematopoietic malignancies, as well as an increased rate of metastasis than ATM(-/-) mice. In conclusion, Gadd45a deletion aggravated the DNA damage accumulation, which subsequently resulted in a further impaired self-renewal capacity and an increased malignant transformation in ATM(-/-) HSCs.

Efeitos colaterais tardios na bexiga após radioterapia por câncer de colo de útero: avaliação da associação com polimorfismos de TP53, ATM e MDM2 / Late urinary bladder side effects after radiotherapy for cervical cancer: evaluation of the association with TP53, ATM and MDM2 polymorphisms

Introdução: Na prática clínica se observa que há diferenças na incidência de efeitos colaterais entre pacientes submetidos ao mesmo esquema terapêutico de radioterapia. Tais diferenças podem ser entendidas como uma radiossensibilidade individual determinada geneticamente. Objetivos: Este estudo teve como objetivo avaliar os efeitos tardios na bexiga em pacientes com câncer do colo uterino tratadas com radioterapia, com ou sem cirurgia, e o valor prognóstico de três polimorfismos genéticos de base única com relação ao desenvolvimento de cistite actínica. Material e métodos: Foi realizada uma análise retrospectiva de 50 pacientes com carcinoma cervical tratadas entre 1999 e 2004, com um mínimo de 6,5 anos de seguimento. A dose de radioterapia na bexiga foi considerada como a soma da dose da radioterapia externa com a dose de braquiterapia no ponto de bexiga definido pelo ICRU 38 (Relato número 38 da Comissão Internacional de Unidades e Medidas em Radiação). Para as correlações entre dose e efeito, foi calculada a dose biológica efetiva (BED) para cada caso. Para a avaliação dos efeitos tardios em bexiga, além dos dados descritos em prontuário, foi feito um questionário específico dirigido aos sintomas urinários, foi realizada cistoscopia em todas as pacientes e a escala LENTSOMA (efeitos tardios no tecido normal/ subjetivo-objetivo tratamento e exames) foi aplicada, utilizando o pior grau do efeito encontrado nos diferentes métodos de avaliação. Variantes genéticas do códon 72 da p53 (Arginina / Prolina), MDM2 SNP309 T/G e ATMex39 5557 G>A foram identificadas usando o método de genotipagem de SNP ABI SNaPshot e os resultados foram correlacionados com a incidência e grau de cistite actínica. Resultados: Complicações clínicas tardias da bexiga foram registradas em 17 (34%) pacientes usando dados coletados dos prontuários e em 41 (82%) pacientes pelo questionário de existência e gravidade dos efeitos tardios da irradiação. Essas complicações foram diretamente...

Introduction: In clinical practice it is observed that there are differences in the incidence of side effects among patients undergoing the same regimen of radiotherapy. Such differences can be understood as a genetically determined individual radiosensitivity. Purposes: This study aimed to evaluate urinary bladder late effects in patients with uterine cervix cancer treated with radiotherapy with or without surgery and the prognostic value of three single nucleotide polymorphisms (SNPs) related to radiation cystitis. Material and methods: retrospective analysis of 50 patients with cervical carcinoma treated between 1999 and 2004 with a minimum of 6.5 years of follow-up was performed. The radiation dose in the bladder was considered as the dose delivered by external beam irradiation plus the brachytherapy dose in the ICRU Report 38 (International Commission of Radiation Units and Measurements report number 38) bladder point. For dose-effect correlations the biological effective dose (BED) was calculated for each case. For evaluation of bladder late effects, besides the data collected from the charts review, a specific query directed to urinary symptoms was applied to the patients and also a cystoscopy was performed in all of them. The LENTSOMA (late effects of normal tissues/subjective-objective management analytic) scale for bladder late effects was applied. Genetic variants of p53 codon72 (arginine/proline) polymorphism, MDM2 SNP309 T/G and ATMex39 5557G>A were identified by using ABI SNaPshot SNP genotyping method. And the results were correlated with the incidence and grade of radiation cystitis. Results: Clinical late bladder complications were recorded in 17 (34%) patients using data collected from the charts and in 41 (82%) patients by the questionnaire for the existence and severity of late irradiation effects. These complications were directly related with the BED...

Ataxia-Telangiectasia with Novel Splicing Mutations in the ATM Gene

No abstract available.

Influence of reactive oxygen species on mouse bone marrow hematopoietic stem cell apoptosis / 中国实验血液学杂志

Objective of this study was to investigate the mechanism of the biological function damage resulting from increased ROS in peripheral blood stem cells during peripheral blood stem cell transplantation. Bone marrow hematopoietic stem cells (BMHSC) were cultured at the oxygen concentration imitated according to the bone marrow oxygen concentration (5% O2) including mean venous oxygen concentration (12% O2), mean arterial oxygen concentration (20% O2). The ROS level in BMHSC was detected by using fluorescent probe, the percentage of BM-HSC in cell cycle was determined by flow cytometry, the apoptosis rate was assayed by Annexin V/PI double staining, the expression levels of ATM gene and P21 protein were measured by PCR and Western respectively. The results showed that as compared with control group (5% O2), the ROS levels were lower, the percentage of cells in G1, S,G2/M phase increased (P < 0.01), the apoptosis rate of cells obviously increased (P < 0.01), the expression level of ATM gene obviously decreased (P < 0.01), while the expression level of P21 protein significantly was enhanced (P < 0.01) in 12% O2, 20% O2 and 5%-12%-20% O2 groups. It is concluded that ROS results in the apoptosis of BMHSC through inhibiting the expression of ATM gene and activating P21 protein.

Identification of ATM Mutations in Korean Siblings with Ataxia-Telangiectasia

Ataxia-telangiectasia (A-T) is a rare autosomal recessive neurodegenerative disorder. It is characterized by early-onset, progressive cerebellar ataxia, oculomotor apraxia, choreoathetosis, conjunctival telangiectasias, immunodeficiency, and an increased risk of malignancy. Although A-T is known to be the most common cause of progressive cerebellar ataxia in childhood, there have been no confirmed cases in Korea. We report the clinical and genetic findings of Korean siblings who presented with limb and truncal ataxia, oculomotor apraxia, choreoathetosis, and telangiectasias of the eyes. Sequence analysis of the ataxia-telangiectasia mutated (ATM) gene revealed a known missense mutation (c.8546G>C; p.Arg2849Pro) and a novel intronic variant of intron 17 (c.2639-19_2639-7del13). Reverse-transcription PCR and sequencing analysis revealed that the c.2639-19_2639-7del13 variant causes a splicing aberration that potentiates skipping exon 18. Because A-T is quite rare in Korea, the diagnosis of A-T in Korean patients can be delayed. We recommend that a diagnosis of A-T should be suspected in Korean patients exhibiting the clinical features of A-T.

Identification of ATM Mutations in Korean Siblings with Ataxia-Telangiectasia

Ataxia-telangiectasia (A-T) is a rare autosomal recessive neurodegenerative disorder. It is characterized by early-onset, progressive cerebellar ataxia, oculomotor apraxia, choreoathetosis, conjunctival telangiectasias, immunodeficiency, and an increased risk of malignancy. Although A-T is known to be the most common cause of progressive cerebellar ataxia in childhood, there have been no confirmed cases in Korea. We report the clinical and genetic findings of Korean siblings who presented with limb and truncal ataxia, oculomotor apraxia, choreoathetosis, and telangiectasias of the eyes. Sequence analysis of the ataxia-telangiectasia mutated (ATM) gene revealed a known missense mutation (c.8546G>C; p.Arg2849Pro) and a novel intronic variant of intron 17 (c.2639-19_2639-7del13). Reverse-transcription PCR and sequencing analysis revealed that the c.2639-19_2639-7del13 variant causes a splicing aberration that potentiates skipping exon 18. Because A-T is quite rare in Korea, the diagnosis of A-T in Korean patients can be delayed. We recommend that a diagnosis of A-T should be suspected in Korean patients exhibiting the clinical features of A-T.

Multi-gene methylation detection increases positive methylation rate in colorectal cancer / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To study whether combined detection of the methylation status of vimentin, sFRP1, and HPP1 gene can increase the positive methylation rate in colorectal cancer.</p><p><b>METHODS</b>Tissue samples were collected from 90 patients with colorectal cancer, 60 patients with adenomatous polyp, and 20 healthy controls. DNA was extracted and the methylation status of vimentin, sFRP1, and HPP1 gene was detected by Methylation-specific PCR (MSP). The relationship between clinicopathologic features of colorectal cancer and gene methylation was analyzed.</p><p><b>RESULTS</b>The methylation rates of vimentin, sFRP1, and HPP1 were 66.7%, 68.9%, and 72.2% in colorectal cancer, 53.3%, 55.0%, and 50.0% in colorectal adenomas, and 0, 0, and 5.0% in healthy controls, respectively. The methylation of each of the three genes in colorectal cancer tissues was higher than colorectal adenomas and healthy controls(P<0.05). The diagnostic sensitivity by combining three methylation markers was 93.3% in colorectal cancer, 76.7% in colorectal adenomas, which was higher than the sensitivity using single gene testing(P<0.05). No significant associations existed between the methylation status of the three genes and clinical characteristics including sex, age, tumor location, lymph node metastases, distant metastasis, and TNM stage(P>0.05).</p><p><b>CONCLUSIONS</b>DNA methylation levels of vimentin, sFRP1 and HPP1 are significantly higher in colorectal cancer tissue. Combined detection significantly improves the positive rate of methylation, and may be used as early diagnosis method for colorectal cancer.</p>

Functional switching of ATM: sensor of DNA damage in proliferating cells and mediator of Akt survival signal in post-mitotic human neuron-like cells / 癌症

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by cerebellar ataxia and oculocutaneous telangiectasias. The gene mutated in this disease, ATM (A-T, mutated), encodes a 370-kDa Ser/Thr protein kinase. ATM not only mediates cellular response to DNA damage but also acts as an activator of Akt in response to insulin. However, despite intensive studies, the mechanism underlying the neuronal degeneration symptoms of human A-T is still poorly understood. We found that the topoisomerase inhibitors etoposide and camptothecin readily induced apoptosis in undifferentiated proliferating SH-SY5Y cells but could not induce apoptosis in neuronally differentiated SH-SY5Y cells. In addition, etoposide induced p53 phosphorylation and H2AX foci formation in proliferating SH-SY5Y cells but failed to do so in differentiated SH-SY5Y cells. Moreover, while inhibition of ATM in undifferentiated SH-SY5Y cells partially protected them from etoposide-induced apoptosis, the same treatment had no effect on cell viability in differentiated SH-SY5Y cells. These results suggest that DNA damage or defective response to DNA damage is not the cause of neuronal cell death in human A-T. In contrast, we discovered that Akt phosphorylation was inhibited when ATM activity was suppressed in differentiated SH-SY5Y cells. Furthermore, inhibition of ATM induced apoptosis following serum starvation in neuronally differentiated SH-SY5Y cells but could not trigger apoptosis under the same conditions in undifferentiated proliferating SH-SY5Y cells. These results demonstrate that ATM mediates the Akt signaling and promotes cell survival in neuron-like human SH-SY5Y cells, suggesting that impaired activation of Akt is the reason for neuronal degeneration in human A-T.