Ataxia telangiectasia mutated kinase (ATM) is a cell cycle checkpoint protein activated in response to DNA damage. We recently reported that ATM plays a protective role in myocardial remodeling following β-adrenergic receptor stimulation. Here we investigated the role of ATM in cardiac remodeling using myocardial infarction (MI) as a model. Methods and Results: Left ventricular (LV) structure, function, apoptosis, fibrosis, and protein levels of apoptosisand fibrosis-related proteins were examined in wild-type (WT) and ATM heterozygous knockout (hKO) mice 7 days post-MI. Infarct sizes were similar in both MI groups. However, infarct thickness was higher in hKO-MI group. Two dimensional M-mode echocardiography revealed decreased percent fractional shortening (%FS) and ejection fraction (EF) in both MI groups when compared to their respective sham groups. However, the decrease in %FS and EF was significantly greater in WT-MI vs hKO-MI. LV end systolic and diastolic diameters were greater in WT-MI vs hKO-MI. Fibrosis, apoptosis, and α-smooth muscle actin staining was significantly higher in hKO-MI vs WT-MI. MMP-2 protein levels and activity were increased to a similar extent in the infarct regions of both groups. MMP-9 protein levels were increased in the non-infarct region of WT-MI vs WT-sham. MMP-9 protein levels and activity were significantly lower in the infarct region of WT vs hKO. TIMP-2 protein levels similarly increased in both MI groups, whereas TIMP-4 protein levels were significantly lower in the infarct region of hKO group. Phosphorylation of p53 protein was higher, while protein levels of manganese superoxide dismutase were significantly lower in the infarct region of hKO vs WT. In vitro, inhibition of ATM using KU-55933 increased oxidative stress and apoptosis in cardiac myocytes.

Nucleotide excision repair (NER) and ataxia telangiectasia mutated (ATM)/ATR (ATM- and RAD3-related) NA damage checkpoints are among the major pathways that affect the chemotherapeutic efficiency of the anticancer rug cisplatin. Xeroderma pigmentosum group A (XPA) protein plays a crucial role in NER including both global enome repair (GG-NER) and transcription-coupled repair (TC-NER) subpathways, and has been a potential target for mproving cisplatin therapeutic effects. We report here that XPA translocates from the cytosol into the nucleus after NA damage induced by UV irradiation and cisplatin, a mimetic of UV damage, in human cells with or without p53 deficiency. However, the damage-induced response of XPA nuclear import was significantly slower in p53-deficient cells than in p53-proficient cells. We also found that while XPA is imported into the nucleus upon cisplatin or UV damage in an ATR-dependent manner in p53-proficient A549 lung cancer cells, the ATR checkpoint pathway has no effect on the XPA nuclear import in p53-deficient H1299 lung cancer cells. Similarly, the XPA nuclear translocation is not regulated by ATM checkpoint or by p38MAPK/MK2 either. Our findings suggest that NER is independent on the major DNA damage checkpoint pathways in H1299 (p53-/-) cells and that DNA damage responses are mechanistically different between p53-proficient and p53-deficient cells. Our results also highlight the possibility of selectively targeting XPA nuclear import as a way to sensitize cisplatin anticancer activity, but targeting ATR/ATM-dependent checkpoints may not be helpful in killing p53-deficient cancer cells.

Ataxia telangiectasia mutated kinase (ATM) is activated in response to DNA damage. We have previously shown that ATM plays a critical role in myocyte apoptosis and cardiac remodeling after myocardial infarction (MI). Here, we tested the hypothesis that ATM deficiency results in autophagic impairment in the heart early during MI. MI was induced in wild-type (WT) and ATM heterozygous knockout (hKO) mice by ligation of the left anterior descending artery. Structural and biochemical parameters of the heart were measured 4 h after left anterior descending artery ligation. M-mode echocardiography revealed that MI worsens heart function, as evidenced by reduced percent ejection fraction and fractional shortening in both groups. However, MI-induced increase in left ventricular end-diastolic and end-systolic diameters and volumes were significantly lower in hKO hearts. ATM deficiency resulted in autophagic impairment during MI, as evidenced by decreased microtubule-associated protein light chain 3-II increased p62, decreased cathepsin D protein levels, and increased aggresome accumulation. ERK1/2 activation was only observed in WT-MI hearts. Activation of Akt and AMP-activated protein kinase (AMPK) was lower, whereas activation of glycogen synthase kinase (GSK)-3β and mammalian target of rapamycin (mTOR) was higher in hKO-MI hearts. Inhibition of ATM using KU-55933 resulted in autophagic impairment in cardiac fibroblasts, as evidenced by decreased light chain 3-II protein levels and formation of acidic vesicular organelles. This impairment was associated with decreased activation of Akt and AMPK but enhanced activation of GSK-3 β and mTOR in KU-55933-treated fibroblasts. Thus, ATM deficiency results in autophagic impairment in the heart during MI and cardiac fibroblasts. This autophagic impairment may occur via the activation of GSK-3 β and mTOR and inactivation of Akt and AMPK. NEW & NOTEWORTHY Ataxia telangiectasia mutated kinase (ATM) plays a critical role in myocyte apoptosis and cardiac remodeling after myocardial infarction (MI). Here, we provide evidence that ATM deficiency results in autophagic impairment during MI. Further investigation of the role of ATM in autophagy post-MI may provide novel therapeutic targets for patients with ataxia telangiectasia suffering from heart disease.

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12817号 / 論医博第2079号 / 新制||医||1004(附属図書館) / 31304 / 京都大学大学院医学研究科脳統御医科学系専攻 / (主査)教授 河野 憲二, 教授 金子 武嗣, 教授 大森 治紀 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19376号 / 工博第4121号 / 新制||工||1635(附属図書館) / 32390 / 新制||工||1635 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 森 泰生, 教授 梅田 眞郷, 教授 濵地 格 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

This study employed spectral analyses for acoustic measures of sustained vowel productions from a group of 20 adolescents and young adults with Friedreich's Ataxia (FA) and compared findings with a group of 20 age-equivalent and gender-matched normal control participants. State-of-the art spectral analyses from the Analysis of Dysphonia in Speech and Voice (ADSV) program, developed for various voice disorders from Kay Elemetrics, were applied to initial 2 second sustained vowel segments of the vowels /a/, /i/, and /o/. Spectral analyses included averages and standard deviations of Cepstral Peak Prominence (CPP), Cepstral Peak Prominence Standard Deviation (CPP SD), Low/High Spectral Ratio (L/H Ratio), Low/High Spectral Ratio Standard Deviation (L/H Ratio SD), Cepstral/Spectral Index of Dysphonia (CSID), and Mean Cepstral Peak Prominence Fundamental Frequency (Mean CPP F0). Statistical analyses revealed significant differences between the spectral analyses of voice characteristics of individuals with FA and those of normal controls for all measures except for CPP SD. The aim of these analyses was to determine spectral differences evident in vowel productions of individuals with FA using new cepstral-derived measures that characterize the phonatory instability and dis-coordination present in this disorder. Such research may not only help develop early non-invasive indicators of ataxia and track disease progression, but also serve to stimulate research into alleviating the symptoms of this devastating disease.

The purpose of this study was to conduct perceptual analyses, using the initial two-second portions, of prolonged vowels /a/, /i/, and /o/. Two groups of adolescents and young adults were analyzed- one group consisting of 20 individuals with Friedreich's ataxia who were compared to 20 individuals with normal voice (control participants). A trained group of 10 graduate students listened to 132 vowel samples (3 vowels X 40 participants, + 12 samples (10%) for reliability purposes) for a total of 132 perceptual judgments. The students listened to the samples which were randomized onto Dell computers (Optiplex 755) and played through headphones that were set at a comfortable level by the listeners prior to analyzing the voice samples. Listeners used a modified version of the Consensus-Auditory Perceptual Evaluation of Voice (CAPE-VM) to rate the vocal qualities of 'roughness', 'breathiness', and 'strain' in the samples on a 100 millimeter visual analog scale with 0 representing a perception of no roughness, breathiness, or strain, and 100 indicating the most extreme amount of variance from normal voice quality. Statistical analyses were conducted to determine if perceptual measures were significantly different between the two groups. Values on these analyses were expected to be larger for individuals with Friedreich's ataxia than those with normal voice. Results revealed that all three measures were significantly different between the two groups, with those in the Friedreich's ataxia group reported as having increased rough, breathy, and strained components in their voice quality as compared to normal voiced peers. Findings support perceptual measures as useful indicators for reporting changes in the phonatory system due to Friedreich's ataxia.

Ataxia-telangiectasia mutated kinase (ATM) is a serine/threonine kinase. Mutations in the ATM gene cause a rare autosomal multisystemic disease known as Ataxia-telangiectasia (AT). Individuals with mutations in both copies of the ATM gene suffer from increased susceptibility to ionizing radiation, predisposition to cancer, insulin resistance, immune deficiency, and premature aging. Patients with one mutated allele make-up ~1.4 to 2% of the general population. These individuals are spared from most of the symptoms of the disease. However, they are predisposed to developing cancer or ischemic heart disease, and die 7-8 years earlier than the non-carriers. DNA double-strand breaks activate ATM, and active ATM is known to phosphorylate an extensive array of proteins involved in cell cycle arrest, DNA repair, and apoptosis. The importance of ATM in the regulation of DNA damage response signaling is fairly well-established. This review summarizes the role of ATM in the heart, specifically in cardiac remodeling following β-adrenergic receptor stimulation and myocardial infarction.

Background: Technological advancements in speech acoustic analysis have led to the development of spectral/cepstral analyses due to questions regarding the validity of traditional time-based measures (i.e., Jitter, Shimmer, and Harmonics-to-Noise-Ratio) in objectifying perturbations in dysphonic voices. Aim: This study investigated the validity of time-based measures in discriminating those with Friedreich’s ataxia (FA) from normal voiced (NV) peers when compared to cepstral-spectral measures. Method: A total of 120 sustained vowel phonations from an existing database of 40 participants (20 FA; 20 NV) of the vowels /ɑ/, /i/, and /o/ were analyzed to determine which set of variables (i.e., time-based vs. cepstral-spectral) better predicted group membership. Four variables of time-based measures (Jitter Local %, Jitter RAP, Shimmer Local %, Shimmer APQ11, and HNR) were analyzed via the freeware program PRAAT and compared to four cepstral-spectral measures (Cepstral Peak Prominence, Cepstral Peak Prominence Standard Deviation, Low/High Ratio Standard Deviation, and the Cepstral/ Spectral Index of Dysphonia) extracted from the Analysis of Dysphonia in Speech and Voice (ADSV) software program. Results: Findings from a discriminant analysis showed sensitivity and specificity results to be better for ADSV measures; 100% of those in the FA group were classified correctly (sensitivity), and 95% of members in the NV group were correctly identified (specificity) as compared to PRAAT (70% sensitivity and 85% specificity). Conclusions: Cepstral-spectral measures are much more accurate in discriminating between those with FA and NV peers as compared to time-based estimates.

No description available.