Eiji Kojima

The function of GADD34 is a recovery from a shutoff of protein synthesis induced by ER stress: elucidation by GADD34-deficient mice.

GADD34 is a protein that is induced by stresses such as DNA damage. The function of mammalian GADD34 has been proposed by in vitro transfection, but its function in vivo has not yet been elucidated. Here we generated and analyzed GADD34 knockout mice. Despite their embryonic stage‐ and tissue‐specific expressions, GADD34 knockout mice showed no abnormalities at fetal development and in early adult life. However, in GADD34−/− mouse embryonic fibroblasts (MEFs), recovery from a shutoff of protein synthesis was delayed when MEFs were exposed to endoplasmic reticulum (ER) stress. The phosphorylation of eukaryotic translation initiation factor 2 α (eIF2α) at Ser51 induced by thapsigargin or DTT was prolonged in GADD34−/− MEF, although following treatment with tunicamycin, the eIF2α phosphorylation level did not change in either GADD34+/+ or GADD34−/− cells. ER stress stimuli induced expressions of Bip (binding Ig protein) and CHOP (C/EBP homologous protein) in MEF of wild‐type mice. These expressions were strongly reduced in GADD34−/− MEF, which suggests that GADD34 up‐regulates Bip and CHOP. These results indicate that GADD34 works as a sensor of ER stress stimuli and recovers cells from shutoff of protein synthesis.

Heterozygosity with respect to Zfp148 causes complete loss of fetal germ cells during mouse embryogenesis

Zfp148 belongs to a large family of C2H2-type zinc-finger transcription factors. Zfp148 is expressed in fetal germ cells in 13.5-d-old (E13.5) mouse embryos. Germ-line transmission of mutations were not observed in chimeric Zfp148+/− mice, and some of these mice completely lacked spermatogonia. The number of primordial germ cells in Zfp148+/− tetraploid embryos was normal until E11.5, but declined from E11.5 to E13.5 and continued to decline until few germ cells were present at E18.5. This phenotype was not rescued by wild-type Sertoli or stromal cells, and is therefore a cell-autonomous phenotype. These results indicate that two functional alleles of Zfp148 are required for the normal development of fetal germ cells. Recent studies have shown that Zfp148 activates p53, which has an important role in cell-cycle regulation. Primordial germ cells stop proliferating at approximately E13.5, which correlates with induction of phosphorylation of p53 and its translocation to the nucleus. Phosphorylation of p53 is impaired in Zfp148+/− embryonic stem cells and in fetal germ cells from chimeric Zfp148+/− embryos. Thus, Zfp148 may be required for regulating p53 in the development of germ cells.

GADD34 induces p53 phosphorylation and p21/WAF1 transcription

Recently, others and we have shown that one of the functions of GADD34 is a recovery from a shutoff of protein synthesis induced by endoplasmic reticulum stress. GADD34 has been shown to induce growth arrest and apoptosis. Main protein of apoptosis is p53, especially phosphorylation of p53. And one of the main proteins of growth arrest is p21/WAF1. Here we analyzed the effects of GADD34 on p53 phosphorylation and p21/WAF1 transcription. Transfected Myc‐tagged p53 was dose‐dependently phosphorylated at Ser15 by increasing the amount of GADD34. Transfection of GADD34 also induced the endogenous phosphorylation of p53 and enhanced p21 protein expression. Transfection of GADD34 induced p21/WAF1 promoter activity. This activity was dependent on p53, because GADD34 transfection to p53‐deficient cells produced only a slight increase of p21/WAF1 promoter activity. The p21/WAF1 promoter activity was greatly enhanced by the transfection of p53. Both GADD34 and p53 transfection induced much higher p21/WAF1 promoter activity. The promoter activity of p21/WAF1 was very low in GADD34 deficient MEF. The transfection of GADD34 increased the p21/WAF1 promoter activity in GADD34 deficient MEF.

Protein phosphatase 1, but not protein phosphatase 2A, dephosphorylates DNA-damaging stress-induced phospho-serine 15 of p53

Okadaic acid (OA) is a protein phosphatase (PP) inhibitor and induces hyperphosphorylation of p53. We investigated whether the inhibition of PP1 by OA promotes the phosphorylation of the serine 15 of p53. In vitro dephosphorylation assay showed that PP1 dephosphorylated ultraviolet C (UVC)‐induced phospho‐ser15 of p53, and that OA treatment inhibited it. One of the PP1 regulators, growth arrest and DNA damage 34 (GADD34), disturbed PP1 binding with p53, interfered with the dephosphorylation of p53 and increased the amount of phospho‐p53 after UVC‐treatment. This report provides the first evidence that PP1, but not PP2A, dephosphorylates phospho‐serine 15 of p53.

Analysis of the relationship between health status and mortality in hypercapnic patients with noninvasive ventilation

Health status and mortality are important outcomes in patients with advanced pulmonary diseases receiving noninvasive ventilation (NIV). However, their relationship has not been thoroughly investigated.

Validation of the Japanese Severe Respiratory Insufficiency Questionnaire in hypercapnic patients with noninvasive ventilation

BACKGROUND The Severe Respiratory Insufficiency (SRI) Questionnaire was originally developed in German to assess health-related quality of life (HRQL) and was validated as a multidimensional instrument with high psychometric properties in chronic hypercapnic respiratory failure (CHRF) patients receiving noninvasive ventilation (NIV). We aimed to investigate the intercultural adaptation of the Japanese SRI Questionnaire and whether it is a reliable and valid HRQL questionnaire to administer to those patients. METHODS The SRI Questionnaire was adapted to Japanese using a translation and back-translation procedure, followed by equivalency assessment. It was validated in 56 stable outpatients receiving NIV for CHRF, primarily due to chronic obstructive pulmonary disease (COPD) and/or pulmonary tuberculosis sequelae. RESULTS Examination of the frequency distribution of the Japanese SRI Questionnaire showed that the subscales and summary were approximately normally distributed and well balanced. There were no significant differences in SRI scores between patients with COPD and pulmonary tuberculosis sequelae. Cronbach׳s α values representing internal consistency of seven SRI subscales ranged from 0.56 to 0.80; attendant symptoms and sleep had the lowest values. Cronbach׳s α value was 0.92 for the SRI summary. The SRI summary score was significantly related to all eight subscales of the Medical Outcomes Study 36-item short form, with correlation coefficients of 0.41-0.66. CONCLUSIONS The Japanese SRI Questionnaire was produced using a standardized procedure and an equivalency study. It has high psychometric properties with internal consistency and concurrent validity. The Japanese SRI Questionnaire can be used to assess HRQL in patients on NIV for CHRF.

Comparison of Different Disease-Specific Health-Related Quality of Life Measurements in Patients with Long-Term Noninvasive Ventilation

Background Two disease-specific questionnaires have been developed to assess health-related quality of life (HRQL) in patients with chronic respiratory failure: the Severe Respiratory Insufficiency (SRI) Questionnaire and the Maugeri Respiratory Failure (MRF) Questionnaire. We aimed to compare the characteristics of the SRI, MRF-26, and St. Georges Respiratory Questionnaire (SGRQ) for use in patients with home noninvasive ventilation (NIV). Methods Fifty-six outpatients receiving long-term NIV were recruited and underwent assessments of pulmonary function, arterial blood gas, HRQL, dyspnea, and psychological status. Results Correlations of the SRI and MRF-26 with the SGRQ were modest. While pulmonary function was weakly related to only some domains of the SRI and MRF-26, the modified Medical Research Council (mMRC) dyspnea scale and Hospital Anxiety and Depression Scale (HADS) were significantly related to all domains of the SRI and MRF-26. Multiple regression analyses showed that HADS depression and mMRC accounted for 34% and 27% of the variance in the SRI, 24% and 37% in the MRF-26, and 17% and 46% in the SGRQ, respectively. Conclusions The SRI and MRF-26 were reliable questionnaires for patients receiving long-term NIV. Dyspnea and psychological status were their main common determinants. The SRI covers more psychological health impairments than the MRF. This trial is registered with ClinicalTrials.gov Identifier: NCT00905476.

Effect of incorporation of nitrogen atoms in Al2O3 gate dielectric of wide-bandgap-semiconductor MOSFET on gate leakage current and negative fixed charge

We performed first-principle calculations to investigate the effect of incorporation of N atoms into Al2O3 gate dielectrics. Our calculations show that the defect levels generated by VO in Al2O3 are the origin of the stress-induced gate leakage current and that VOVAl complexes in Al2O3 cause negative fixed charge. We revealed that the incorporation of N atoms into Al2O3 eliminates the VO defect levels, reducing the stress-induced gate leakage current. Moreover, this suppresses the formation of negatively charged VOVAl complexes. Therefore, AlON can reduce both stress-induced gate leakage current and negative fixed charge in wide-bandgap-semiconductor MOSFETs.