Characterization of the novel mutant A78T-HERG from a long QT syndrome type 2 patient: instability of the mutant protein and stabilization by heat shock factor 1

Takehito Kondo, Ichiro Hisatome, Shouichi Yoshimura, Endang Mahati, Tomomi Notsu, Peili Li, Kazuhiko Iitsuka, Masaru Kato, Kazuyoshi Ogura, Junichiro Miake, Takeshi Aiba, Wataru Shimizu, Yasutaka Kurata, Shinji Sakata, Naoe Nakasone, Haruaki Ninomiya, Akira Nakai, Katsumi Higaki, Yasushi Kawata, Yasuaki Shirayoshi, Akio Yoshida, Kazuhiro Yamamoto. Characterization of the novel mutant A78T-HERG from a long QT syndrome type 2 patient: Instability of the mutant protein and stabilization by heat shock factor 1. Journal of Arrhythmia. 2015

Characterization of the novel mutant A78T-HERG from a long QT syndrome type 2 patient: Instability of the mutant protein and stabilization by heat shock factor 1

Background:The human ether-a-go-go-related gene (HERG) encodes the α-subunit of rapidly activating delayed-rectifier potassium channels. Mutations in this gene cause long QT syndrome type 2 (LQT2). In most cases, mutations reduce the stability of the channel protein, which can be restored by heat shock (HS). Methods: We identified the novel mutant A78T-HERG in a patient with LQT2. The purpose of the current study was to characterize this mutant protein and test whether HS and heat shock factors (HSFs) could stabilize the mutant protein. A78T-HERG and wild-type HERG (WT-HERG) were expressed in HEK293 cells and analyzed by immunoblotting, immunoprecipitation, immunofluorescence, and whole-cell patch clamping. Results: When expressed in HEK293 cells, WT-HERG gave rise to immature and mature forms of the protein at 135 and 155 kDa, respectively. A78T-HERG gave rise only to the immature form, which was heavily ubiquitinated. The proteasome inhibitor MG132 increased the expression of immature A78T-HERG and increased both the immature and mature forms of WT-HERG. WT-HERG, but not A78T-HERG, was expressed on the plasma membrane. In whole-cell patch clamping experiments, depolarizing pulses evoked E4031-sensitive HERG channel currents in cells transfected with WT-HERG, but not in cells transfected with A78T-HERG. The A78V mutant, but not A78G mutant, remained in the immature form similarly to A78T. Maturation of the A78T-HERG protein was facilitated by HS, expression of HSF-1, or exposure to geranyl geranyl acetone. Conclusions: A78T-HERG was characterized by protein instability and reduced expression on the plasma membrane. The stability of the mutant was partially restored by HSF-1, indicating that HSF-1 is a target for the treatment for LQT2 caused by the A78T mutation in HERG

Effect of diabetes and prediabetes on the development of disability and mortality among middle-aged Japanese adults : A 22-year follow up of NIPPON DATA90.

Aims/introduction:To examine the association between diabetes and prediabetes at baseline, and disability, mortality over a 22-year period among middle-aged Japanese adults.Materials and methods:Participants consisted of 1,788 adults aged 45-64 years at baseline from the cohort study National Integrated Project for Prospective Observation of Non-communicable Disease and its Trends in the Aged 1990 (NIPPON DATA90). Disability, defined as having a decline in activities of daily living (ADL), was assessed by a modified Katz questionnaire at four time points. Disability and death without disability for 22-year follow up were used as outcomes to test the association with a diagnosis of diabetes or prediabetes at baseline, using multinomial logistic regression. Adjusted odds ratios (ORs) were obtained from four models that contained appropriate adjustment factors, such as age, sex, smoking status, drinking status, body mass index and cardiovascular risk factors (hypertension, hypercholesterolemia, triglycerides, low serum high-density lipoprotein), at baseline.Results:In the present study, 334 participants (18.7%) reported at least one disability, and 350 (19.6%) were reported dead without observation of disability during follow up. Adjusting sex and other risk factors, participants with diabetes and prediabetes had a higher risk for disability (OR 1.43, 95% confidence interval [CI] 1.07-1.91 and OR 1.66, 95% CI 1.10-2.50, respectively) and for mortality (OR 1.56, 95% CI 1.16-2.08 and OR 1.77, 95% CI 1.18-2.65, respectively) than individuals with normal glucose tolerance.Conclusions:In middle-aged Japanese adults, individuals with diabetes and prediabetes were more likely to be associated with disability and mortality. Our findings suggest that prediabetes and diabetes in middle-aged adults should be paid more attention, and requires more intervention to prevent disability and mortality in later life

Skeletal analysis of the long bone abnormality (lbab/lbab) mouse, a novel chondrodysplastic C-type natriuretic peptide mutant.

Long bone abnormality (lbab/lbab) is a strain of dwarf mice. Recent studies revealed that the phenotype is caused by a spontaneous mutation in the Nppc gene, which encodes mouse C-type natriuretic peptide (CNP). In this study, we analyzed the chondrodysplastic skeletal phenotype of lbab/lbab mice. At birth, lbab/lbab mice are only slightly shorter than their wild-type littermates. Nevertheless, lbab/lbab mice do not undergo a growth spurt, and their final body and bone lengths are only ~60% of those of wild-type mice. Histological analysis revealed that the growth plate in lbab/lbab mice, especially the hypertrophic chondrocyte layer, was significantly thinner than in wild-type mice. Overexpression of CNP in the cartilage of lbab/lbab mice restored their thinned growth plate, followed by the complete rescue of their impaired endochondral bone growth. Furthermore, the bone volume in lbab/lbab mouse was severely decreased and was recovered by CNP overexpression. On the other hand, the thickness of the growth plate of lbab/+ mice was not different from that of wild-type mice; accordingly, impaired endochondral bone growth was not observed in lbab/+ mice. In organ culture experiments, tibial explants from fetal lbab/lbab mice were significantly shorter than those from lbab/+ mice and elongated by addition of 10(-7) M CNP to the same extent as lbab/+ tibiae treated with the same dose of CNP. These results demonstrate that lbab/lbab is a novel mouse model of chondrodysplasia caused by insufficient CNP action on endochondral ossification

Smoking is Associated With Impaired Long-term Quality of Life in Elderly People: A 22-year Cohort Study in NIPPON-DATA 90

Background: Whether smoking is associated with worse quality of life (QoL) or not is relatively controversial. The current study is to investigate the relationship between smoking and subjective QoL in a long cohort study. Methods: The NIPPON DATA 90 project collected 8,383 community residents in 300 randomly selected areas as baseline data in 1990, administered four follow-up QoL surveys, and evaluated mortality statistics. We conducted multinomial logistic regression analysis to compare past smokers and current smokers to never smokers, with impaired QoL and mortality as outcomes. Results: In four follow-ups, QoL data was collected from 2,035, 2,252, 2,522, and 3,280 participants in 1995, 2000, 2005, and 2012, respectively. In the 1995 follow-up, current smoking at baseline was not associated with worse QoL. In 2000 and 2005 follow-ups, smoking was significantly associated with worse QoL (odds ratio [OR] 2.1; 95% confidence interval [CI], 1.33–3.36 and OR 2.29; 95% CI, 1.38–3.80, respectively). In the 2012 follow-up, smoking was not associated with QoL. Sensitivity analysis did not change the result significantly. Conclusion: In this study we found that baseline smoking was associated with worse QoL in long-follow-up

Clinicopathologic characteristics and A20 mutation in primary thyroid lymphoma

博士（医学）乙日本医科大学202

Differences in Lifestyle Improvements With the Intention to Prevent Cardiovascular Diseases by Socioeconomic Status in a Representative Japanese Population: NIPPON DATA2010

Background: The relationships among socioeconomic status and lifestyle improvements have not yet been examined in a representative Japanese population. Methods: We analyzed data from 2,647 participants (1,087 men and 1,560 women) who participated in NIPPON DATA2010. This survey inquired about lifestyle improvements and socioeconomic status. Education was categorized as low (≤9 years), middle (10–12 years), and high (≥13 years). Marital status was categorized as married, divorced, widowed, and never married/other. A multivariable logistic regression model was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of lifestyle improvements with the intention of preventing cardiovascular diseases for educational attainment and marital status, with adjustments for age and awareness of cardiovascular disease risk factors. Results: Overall, 1,507 (56.9%) participants practiced prevention and improvements in hypertension, diabetes, elevated cholesterol, and metabolic syndrome, and the OR of lifestyle improvements was significantly higher with a high education than with a low education in men (OR 2.86; 95% CI, 1.96–4.17) and women (OR 2.36; 95% CI, 1.67–3.33). The number of participants who practiced prevention and improvements in hypertension, diabetes, elevated cholesterol, and metabolic syndrome was significantly lower in divorced than in married men (OR 0.46; 95% CI, 0.22–0.95) and women (OR 0.53; 95% CI, 0.33–0.86). Conclusions: Specific differences caused by educational attainment and marital status may exist in lifestyle improvements