Matsuzaki Masanori

Aberrant increases in protein phosphatase 1(PP1) activity have been shown to be associated with inefficient sarcoplasmic reticulum Ca^{2+} cycling, leading to cardiac dysfunction in the failing heart. In the present study, we investigated whether BNP promoter-inducible suppression of PP1β would ameliorate progression of pressure overload-induced heart failure in mice, a clinically relevant animal model. An Adeno-associated virus 9 (AAV9) vector encoding PP1βshRNA and a negative control (NC) shRNA driven by a brain natriuretic peptide (BNP) promoter with an emerald green fluorescent protein expression (EmGFP) cassette were used to test the hypothesis. AAV9 vectors (AAV9-BNP-EmGFP-PP1βshRNA and AAV9-BNP-EmGFP-NCshRNA) were introduced into the in vivo heart via the tail vein injection (4x10^{11} GC/mice) in 8-week-old C57BL6J mice, followed by transverse aortic constriction (TAC) 2 weeks after the AAV9 vector injection. Post TAC cardiac function was sequentially assessed every 2 week by echocardiography, followed by hemodynamic assessment at 1 month. AAV9-BNP-EmGFP-PP1βshRNA treatment suppressed myocardial PP1β expression by 15% compared with the NCshRNA group (p<0.001). The fractional shortening (%FS) of the left ventricle in the PP1βshRNA-treated group was significantly larger than the NCshRNA-treated group (21%±1.0% vs. 15%±0.01, p<0.01). The ratios of heart weight (HW) / body weight (BW) and lung weight (LW) / BW in the PP1βshRNA group were significantly smaller than those of the NCshRNA group (HW/BW: 9.20±0.49 vs. 10.6±0.45 mg/g

Background: Angiotensin II (AngII) increases reactive oxygen species (ROS) and induces glomerular sclerosis. Toll-like receptor 4 (TLR4)-mediated inflammation enhances the renal impairment in renal inflammatory diseases. The relationship between TLR4 and AngII-induced glomerular sclerosis is unknown.Methods: Mice lacking TLR4 function (Tlr4^{lps-d}) and wild-type (WT) mice were randomized into groups treated with AngII, norepinephrine (NE) or a sub-depressor dose of the AngII receptor blocker irbesartan along with AngII for 2 weeks. We then assessed the expressions of NADPH oxidase and monocyte chemoattractant protein-1 (MCP-1) and the inflammatory cell recruitment in the glomeruli. We also evaluated the mesangial matrix proliferation and ROS.Results: AngII and NE equally increased the systolic blood pressure compared to the control mice (p<0.05). In the WT mice treated with AngII, we observed glomerular sclerosis, an increase in NADPH oxidase, MCP-1 and the infiltration of macrophages as well as ROS content in the glomeruli compared to the control mice (p<0.05), whereas the Tlr4^{lps-d} mice showed little effects of AngII on these indices. In addition, the sub-depressor-dose irbesartan treatment reversed these changes. NE had little effects on these indices. Conclusions: TLR4 plays an important role in AngII-induced oxidative stress, inflammation and glomerular sclerosis through the AT1 receptor.

We investigated the relationship between myocardial oxidative stress and cardiac sympathetic hyperactivity in patients with takotsubo cardiomyopathy (TC) compared with acute anteroseptal myocardial infarction (AMI). Methods: In 10 TC patients and 10 AMI patients, electrocardiogram, echocardiography, cardiac catheterization were conducted, and plasma catecholamines and urinary (U) 8-hydroxy-2’-deoxyguanosine (8-OHdG) as a marker of oxidative DNA damage were taken for one week from onset. Results: On admission, the coronary sinus (CS) had significantly higher norepinephrine (NE) and 8-OHdG levels than the aortic root (Ao) and peripheral blood vessels. Circulating catecholamines in TC patients tended to be higher than those in AMI patients

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited disease characterized by stress- or exercise- induced ventricular tachycardia, frequently leading to sudden cardiac death. A considerable body of evidence accumulated over recent years suggests that mutation-linked cardiac ryanodine receptor (RyR2) defects cause Ca^2+ leak from sarcoplasmic reticulum, which triggers delayed afterdepolarization and leads to CPVT. However, the underlying mechanism, by which a single mutation in such a large molecule causes drastic effects on the channel function, remains elusive. Here we report that introduction of a human CPVT mutation S2246L into the mouse RyR2 induces aberrant activation of channel gating by forming abnormally tight domain-domain interaction between the S2246L mutable domain and the K201-binding domain. This produces more global conformational change in the RyR2: namely, an aberrant domain unzipping between the N-terminal (a.a. 1–600) domain and the central (a.a. 2000–2500) domain owing to the allosteric conformational coupling mechanism. Pharmacological correction of the defective inter-domain interactions can stop the aberrant Ca^2+ release and lethal arrhythmia. These results provide a new pathogenic mechanism of CPVT and a novel therapeutic strategy against CPVT