Arrhythmias, a common cause of sudden cardiac death, can occur in structurally normal hearts, although the mechanism is not known. In cardiac muscle, the ryanodine receptor (RyR2) on the sarcoplasmic reticulum releases the calcium required for muscle contraction. The FK506 binding protein (FKBP12.6) stabilizes RyR2, preventing aberrant activation of the channel during the resting phase of the cardiac cycle. We show that during exercise, RyR2 phosphorylation by cAMP-dependent protein kinase A (PKA) partially dissociates FKBP12.6 from the channel, increasing intracellular Ca(2+) release and cardiac contractility. FKBP12.6(-/-) mice consistently exhibited exercise-induced cardiac ventricular arrhythmias that cause sudden cardiac death. Mutations in RyR2 linked to exercise-induced arrhythmias (in patients with catecholaminergic polymorphic ventricular tachycardia [CPVT]) reduced the affinity of FKBP12.6 for RyR2 and increased single-channel activity under conditions that simulate exercise. These data suggest that "leaky" RyR2 channels can trigger fatal cardiac arrhythmias, providing a possible explanation for CPVT.

Increasing evidence suggests that perturbations in the intestinal microbiota composition of infants are implicated in the pathogenesis of food allergy (FA), while the actual structure and composition of the intestinal microbiota in human beings with FA remain unclear. Microbial diversity and composition were analyzed with parallel barcoded 454 pyrosequencing targeting the 16S rRNA gene hypervariable V1-V3 regions in the feces of 34 infants with FA (17 IgE mediated and 17 non-IgE mediated) and 45 healthy controls. Here, we showed that several key FA-associated bacterial phylotypes, but not the overall microbiota diversity, significantly changed in infancy fecal microbiota with FA and were associated with the development of FA. The proportion of abundant Bacteroidetes, Proteobacteria, and Actinobacteria phyla were significantly reduced, while the Firmicutes phylum was highly enriched in the FA group (P < 0.05). Abundant Clostridiaceae 1 organisms were prevalent in infants with FA at the family level (P ‫؍‬ 0.016). FA-enriched phylotypes negatively correlated with interleukin-10, for example, the genera Enterococcus and Staphylococcus. Despite profound interindividual variability, levels of 20 predominant genera were significantly different between the FA and healthy control groups (P < 0.05). Infants with IgE-mediated FA had increased levels of Clostridium sensu stricto and Anaerobacter and decreased levels of Bacteroides and Clostridium XVIII (P < 0.05). A positive correlation was observed between Clostridium sensu stricto and serum-specific IgE (R ‫؍‬ 0.655, P < 0.001). The specific microbiota signature could distinguish infants with IgE-mediated FA from non-IgE-mediated ones. Detailed microbiota analysis of a well-characterized cohort of infants with FA showed that dysbiosis of fecal microbiota with several FA-associated key phylotypes may play a pathogenic role in FA.

The prevalence of mutations in cancer susceptibility genes such as and and other cancer susceptibility genes and their clinical relevance are largely unknown among a large series of unselected breast cancer patients in the Chinese population. A total of 8,085 consecutive unselected Chinese breast cancer patients were enrolled. Germline mutations in 46 cancer susceptibility genes were detected using a 62-gene panel. Pathogenic mutations were identified in 9.2% of patients among the 8,085 unselected breast cancer patients. Of these, 5.3% of patients carried a or mutation (1.8% in and 3.5% in), 2.9% carried other breast cancer susceptibility genes (BOCG) and 1.0% carried another cancer susceptibility genes. Triple-negative breast cancers had the highest prevalence of mutations (11.2%) and other BOCG mutations (3.8%) among the four molecular subgroups, whereas ER/PRHER2 breast cancers had the lowest mutations in (1.8%) and BOCG (1.6%). In addition, mutation carriers had a significant worse disease-free survival [unadjusted hazard ratio (HR) 1.60; 95% confidence interval (CI) 1.10-2.34; = 0.014] and disease-specific survival (unadjusted HR 1.96; 95% CI, 1.03-3.65; = 0.040) than did non-carriers, whereas no significant difference in survival was found between mutation carriers and non-carriers. 9.2% of breast cancer patients carry a pathogenic mutation in cancer susceptibility genes in this large unselected series. Triple-negative breast cancers have the highest prevalence of mutations in and other breast cancer susceptibility genes among the four molecular subgroups, whereas ER/PRHER2 breast cancers had the lowest mutations in these genes. .

Abnormalities in intracellular calcium release and reuptake are responsible for decreased contractility in heart failure (HF). We have previously shown that cardiac ryanodine receptors (RyRs) are protein kinase A-hyperphosphorylated and depleted of the regulatory subunit calstabin-2 in HF. Moreover, similar alterations in skeletal muscle RyR have been linked to increased fatigability in HF. To determine whether restoration of calstabin binding to RyR may ameliorate cardiac and skeletal muscle dysfunction in HF, we treated WT and calstabin-2 ؊/؊ mice subjected to myocardial infarction (MI) with JTV519. JTV519, a 1,4-benzothiazepine, is a member of a class of drugs known as calcium channel stabilizers, previously shown to increase calstabin binding to RyR. Echocardiography at 21 days after MI demonstrated a significant increase in ejection fraction in WT mice treated with JTV519 (45.8 ؎ 5.1%) compared with placebo (31.1 ؎ 3.1%; P < 0.05). Coimmunoprecipitation experiments revealed increased amounts of calstabin-2 bound to the RyR2 channel in JTV519-treated WT mice. However, JTV519 did not show any of these beneficial effects in calstabin-2 ؊/؊ mice with MI. Additionally, JTV519 improved skeletal muscle fatigue in WT and calstabin-2 ؊/؊ mice with HF by increasing the binding of calstabin-1 to RyR1. The observation that treatment with JTV519 improved cardiac function in WT but not calstabin-2 ؊/؊ mice indicates that calstabin-2 binding to RyR2 is required for the beneficial effects in failing hearts. We conclude that JTV519 may provide a specific way to treat the cardiac and skeletal muscle myopathy in HF by increasing calstabin binding to RyR.calcium ͉ FKBP12.6 ͉ myocardial infarction ͉ contractility