Posttranslational regulation of multiple clock-related transcription factors triggers cold-inducible gene expression in Arabidopsis.

Cold stress is an adverse environmental condition that affects plant growth, development, and crop productivity. Under cold stress conditions, the expression of numerous genes that function in the stress response and tolerance is induced in various plant species, and the dehydration-responsive element (DRE) binding protein 1/C-repeat binding factor (DREB1/CBF) transcription factors function as master switches for cold-inducible gene expression. Cold stress strongly induces these DREB1 genes. Therefore, it is important to elucidate the mechanisms of DREB1 expression in response to cold stress to clarify the perception and response of cold stress in plants. Previous studies indicated that the central oscillator components of the circadian clock, CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), are involved in cold-inducible DREB1 expression, but the underlying mechanisms are not clear. We revealed that the clock-related MYB proteins REVEILLE4/LHY-CCA1-Like1 (RVE4/LCL1) and RVE8/LCL5 are quickly and reversibly transferred from the cytoplasm to the nucleus under cold stress conditions and function as direct transcriptional activators of DREB1 expression. We found that CCA1 and LHY suppressed the expression of DREB1s under unstressed conditions and were rapidly degraded specifically in response to cold stress, which suggests that they act as transcriptional repressors and indirectly regulate the cold-inducible expression of DREB1s We concluded that posttranslational regulation of multiple clock-related transcription factors triggers cold-inducible gene expression. Our findings clarify the complex relationship between the plant circadian clock and the regulatory mechanisms of cold-inducible gene expression.

Carotid Intima-media Thickness and Small Dense Low-density Lipoprotein Cholesterol Increase after One Year of Treatment with Direct-acting Antivirals in Patients with Hepatitis C Virus Infection.

Objective Direct-acting antivirals (DAAs) for treating hepatitis C virus (HCV) infection exert a significantly high sustained viral response (SVR), and patients experience a rebound increase in low-density lipoprotein cholesterol (LDL) and total cholesterol levels. Carotid intima-media thickness (IMT) is a highly reproducible and non-invasive parameter for assessing the atherosclerotic process, and the small dense (sd) LDL level is useful for clinically evaluating the atherogenic risk. Methods A total of 48 patients with chronic HCV infection were treated with DAAs. All patients exhibited an SVR 24 weeks later. We compared the metabolic profiles of the patients, including the sdLDL and IMT values, at the start of DAA treatment with those after one year of treatment. We verified whether the HCV clearance after the administration of DAAs is associated with the development of atherosclerosis. Results The sdLDL, %sdLDL (sdLDL/LDL), and LDL values were exacerbated after a year of treatment; however, the triglyceride level, glycated hemoglobin level, insulin resistance, and body weight remained unaltered. The max-IMT was increased after a year compared to that at the start of treatment. Differences in the max-IMT (dmax-IMT) were greater in men than in women; however, no correlation was observed between the dmax-IMT and genotype, fibrosis, hypertension, hyperlipidemia, diabetes, obesity, and dialysis status. The %sdLDL at the start and a year later was positively correlated with the dmax-IMT. No correlation was observed among various factors including the LDL, triglyceride, body mass index, insulin resistance and dmax-IMT. In uni- and multivariate analyses, a significant correlation was observed between %sdLDL≥16% at the start of treatment and the sex and dmax-IMT. Conclusion Because the sdLDL and IMT values were exacerbated after a year of DAA treatment, atherosclerosis must be evaluated in patients achieving an SVR.

Intracerebroventricular injection of ghrelin decreases wheel running activity in rats.

There is an increasing interest in elucidating the molecular mechanisms by which voluntary exercise is regulated. In this study, we examined how the central nervous system regulates exercise. We used SPORTS rats, which were established in our laboratory as a highly voluntary murine exercise model. SPORTS rats showed lower levels of serum ghrelin compared with those of the parental line of Wistar rats. Intracerebroventricular and intraperitoneal injection of ghrelin decreased wheel-running activity in SPORTS rats. In addition, daily injection of the ghrelin inhibitor JMV3002 into the lateral ventricles of Wistar rats increased wheel-running activity. Co-administration of obestatin inhibited ghrelin-induced increases in food intake but did not inhibit ghrelin-induced suppression of voluntary exercise in rats. Growth hormone secretagogue receptor (GHSR) in the hypothalamus and hippocampus of SPORTS rats was not difference that in control rats. We created an arcuate nucleus destruction model by administering monosodium glutamate (MSG) to neonatal SPORTS rats. Injection of ghrelin into MSG-treated rats decreased voluntary exercise but did not increase food intake, suggesting that wheel-running activity is not controlled by the arcuate nucleus neurons that regulate feeding. These results provide new insights into the mechanism by which ghrelin regulates voluntary activity independent of arcuate nucleus neurons.

Enhancement of endothelial function inhibits left atrial thrombi development in an animal model of spontaneous left atrial thrombosis.

BACKGROUND: Left atrial (LA) thrombosis is an important cause of systemic embolization. The SPORTS rat model of LA thrombi (Spontaneously-Running Tokushima-Shikoku), which have a unique characteristic of high voluntary wheel running, was previously established. The aim of the present study was to investigate how SPORTS rats develop LA thrombi. METHODS AND RESULTS: Nitric oxide (NO) produced from cardiovascular endothelial cells plays an important protective role in the local regulation of blood flow, vascular tone, and platelet aggregation. No evidence of atrial fibrillation or hypercoagulability in SPORTS rats regardless of age was found; however, SPORTS rats demonstrated endothelial dysfunction and a decrease of NO production from a young age. In addition, endothelial NO synthase activity was significantly decreased in the LA and thoracic aorta endothelia of SPORTS rats. While voluntary wheel running was able to intermittently increase NO levels, running did not statistically decrease the incidence of LA thrombi at autopsy. However, L-arginine treatment significantly increased NO production and provided protection from the development of LA thrombi in SPORTS rats. CONCLUSIONS: They present study results indicate that NO has an important role in the development of LA thrombus, and endothelia pathways could provide new targets of therapy to prevent LA thrombosis.

Establishment of a model of spontaneously-running-Tokushima-shikoku rats with left atrial thrombosis.

Studies that investigate the underlying mechanisms of disease and treatment options typically require the use of a suitable animal model. Few suitable animal models exist for left atrial thrombosis. Here, we demonstrated that the Spontaneously-Running-Tokushima-Shikoku (SPORTS) rat - a Wistar strain known for its running ability-is predisposed to the development of thrombi in the left atrium. We investigated the incidence of left atrial thrombosis in male (n = 16) and female (n = 17) SPORTS rats and observed organized atrial thrombosis in 57% and 38% of males and female rats, respectively. In the male rats, systolic blood pressures and heart rates were significantly higher in SPORTS rats than in control Wistar rats. We could not find any evidence of arrhythmias, such as atrial fibrillation, during electrocardiographic examination of SPORTS rats. We believe that the SPORTS rat could serve as a new research model for left atrial thrombosis; further, it may be suitable for research investigating the development of new antithrombotic approaches for the control of atrial thrombosis or familial thrombophilia in humans.

Beta-adrenergic-AMPK pathway phosphorylates acetyl-CoA carboxylase in a high-epinephrine rat model, SPORTS.

We established a new animal model called SPORTS (Spontaneously-Running Tokushima-Shikoku) rats, which show high-epinephrine (Epi) levels. Recent reports show that Epi activates adenosine monophosphate (AMP)-activated protein kinase (AMPK) in adipocytes. Acetyl-CoA carboxylase (ACC) is the rate-limiting enzyme in fatty acid synthesis, and the enzymatic activity is suppressed when its Ser-79 is phosphorylated by AMPK. The aim of this study was to investigate the in vivo effect of Epi on ACC and abdominal visceral fat accumulation. We divided both 6-week male control and SPORTS rats into two groups, which were fed either normal diet or high fat and sucrose (HFS) diet for 16 weeks. At the end of diet treatment, retroperitoneal fat was collected for western blotting and histological analysis. Food intake was not different among the groups, but SPORTS rats showed significantly lower weight gain than control rats in both diet groups. After 10 weeks of diet treatment, glucose tolerance tests (GTTs) revealed that SPORTS rats had increased insulin sensitivity. Furthermore, SPORTS rats had lower quantities of both abdominal fat and plasma triglyceride (TG). In abdominal fat, elevated ACC Ser-79 phosphorylation was observed in SPORTS rats and suppressed by an antagonist of beta-adrenergic receptor (AR), propranolol, or an inhibitor of AMPK, Compound C. From these results, high level of Epi induced ACC phosphorylation mediated through beta-AR and AMPK signaling pathways in abdominal visceral fat of SPORTS rats, which may contribute to reduce abdominal visceral fat accumulation and increase insulin sensitivity. Our results suggest that beta-AR-regulated ACC activity would be a target for treating lifestyle-related diseases, such as obesity.