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

Long-chain fatty acids (FAs) are the predominant energy substrate utilized by the adult heart. The heart can utilize unesterified FA bound to albumin or FA obtained from lipolysis of lipoprotein-bound triglyceride (TG). We used heart-specific lipoprotein lipase knock-out mice (hLpL0) to test whether these two sources of FA are interchangeable and necessary for optimal heart function. Hearts unable to obtain FA from lipoprotein TG were able to compensate by increasing glucose uptake, glycolysis, and glucose oxidation. HLpL0 hearts had decreased expression of pyruvate dehydrogenase kinase 4 and increased cardiomyocyte expression of glucose transporter 4. Conversely, FA oxidation rates were reduced in isolated perfused hLpL0 hearts. Following abdominal aortic constriction expression levels of genes regulating FA and glucose metabolism were acutely up-regulated in control and hLpL0 mice, yet all hLpL0 mice died within 48 h of abdominal aortic constriction. Older hLpL0 mice developed cardiac dysfunction characterized by decreased fractional shortening and interstitial and perivascular fibrosis. HLpL0 hearts had increased expression of several genes associated with transforming growth factor-␤ signaling. Thus, long term reduction of lipoprotein FA uptake is associated with impaired cardiac function despite a compensatory increase in glucose utilization.Normal cardiac muscle function requires adequate delivery of oxygen and energy substrates for the production of ATP. In the adult heart, fatty acid (FA) 4 oxidation accounts for 60 -70% of oxygen consumption, with the balance provided by glucose and lactate (1-3). However, during conditions such as ischemia (4, 5) and hypertrophy (4 -6) the heart becomes more dependent on glucose. This initial adaptive response is beneficial in that it maintains ATP levels (7, 8) in the face of diminished mitochondrial oxidative phosphorylation. High rates of FA oxidation inhibit glucose oxidation and impair the recovery of mechanical function during reperfusion of ischemic hearts (9), whereas partial inhibition of FA oxidation during acute ischemia increases glucose oxidation and improves contractile power and efficiency (10 -12). Several pharmacological agents have been developed, including dichloroacetate and ranolazine, which increase glucose oxidation in isolated hearts subjected to ischemia (4, 12). Furthermore, trimetazine, an inhibitor of long-chain 3-ketoacyl-coenzyme A thiolase (the final enzyme in the ␤-oxidation pathway), is cardioprotective in several models of ischemia (13). However, the long term effects of reduced FA oxidation on cardiac energetics and function are unknown.All tissues have several routes through which they may acquire FAs. The heart avidly utilizes FA associated with albumin, and this can be demonstrated both in vivo and in perfused hearts. However, esterified FAs contained in lipoproteins are the major source of cardiac FA (14). These two sources of FA can compete for uptake in perfused hearts (15); this is not surprising, because conversion of TG to ...

The genetic cause for approximately 80% of familial breast cancer patients is unknown. Here, by sequencing the entire exomes of nine early-onset familial breast cancer patients without BRCA1/2 mutations (diagnosed with breast cancer at or before the age of 35) we found that two index cases carried a potentially deleterious mutation in the RECQL gene (RecQ helicase-like; chr12p12). Recent studies suggested that RECQL is involved in DNA double-strand break repair and it plays an important role in the maintenance of genomic stability. Therefore, we further screened the RECQL gene in an additional 439 unrelated familial breast cancer patients. In total, we found three nonsense mutations leading to a truncated protein of RECQL (p.L128X, p.W172X, and p.Q266X), one mutation affecting mRNA splicing (c.395-2A>G), and five missense mutations disrupting the helicase activity of RECQL (p.A195S, p.R215Q, p.R455C, p.M458K, and p.T562I), as evaluated through an in vitro helicase assay. Taken together, 9 out of 448 BRCA-negative familial breast cancer patients carried a pathogenic mutation of the RECQL gene compared with one of the 1,588 controls (P = 9.14×10-6). Our findings suggest that RECQL is a potential breast cancer susceptibility gene and that mutations in this gene contribute to familial breast cancer development.

We determined the prevalence and characteristics of BRCA1/2 germline mutations in a large cohort of Chinese women with breast cancer. A total of 5931 unselected Chinese women with breast cancer were enrolled in this study and underwent testing for BRCA1/2 mutations. Of these, 543 patients were familial breast cancer, 1033 were early-onset disease (≤40 years) without family history of breast cancer, and 4355 were sporadic breast cancer. In total, 232 patients (3.9 %) carried a BRCA1 or BRCA2 mutation (110 in BRCA1and 122 in BRCA2) in this cohort of 5931 patients. BRCA1/2 mutation rate was 16.9 % (92/543) in familial breast cancers, 5.2 % (54/1033) in early-onset breast cancers (≤40 years), and 2.0 % in sporadic breast cancers (>40 years), respectively. The BRCA1/2 mutation rate was 27.0 % in 111 familial breast cancers diagnosed at and before the age of 40. 41.4 % of mutations in this cohort were specific for Chinese population. Recurrent mutations accounted for 44.8 % of the entire mutations in 2382 cases that BRCA1 and BRCA2 genes were fully sequenced in this study. Both BRCA1 and BRCA2 mutation carriers were significantly more likely to be early-onset and bilateral breast cancers, high-grade cancer, and to have a family history of breast cancer compared with non-carriers. BRCA1 mutation carriers were more likely to be triple-negative cancer than BRCA2 mutation carriers and non-carriers. Our data provide guidelines for Chinese women with breast cancer who should undergo BRCA1/2 genetic testing; additionally, recurrent mutations account for nearly half of the mutations and some of them are specific for Chinese women.

Background The Wnt/β-catenin signaling pathway plays a central role during cardiac development and has been implicated in cardiac remodeling and aging. However, the role of Wnt modulators in this process is unknown. In the present study, we examined the role of the Wnt signaling inhibitor sFRP-1 in aged wildtype and sFRP-1 deficient mice. Methods and Results sFRP-1 gene deletion mice were grossly normal with no difference in mortality but developed abnormal cardiac structure and dysfunction with progressive age. Ventricular dilation and hypertrophy in addition to deterioration of cardiac function and massive cardiac fibrosis, all features present in dilated cardiomyopathy was observed in the aged sFRP-1 KO mice when aged. Loss of sFRP-1 led to increased expression of Wnt ligands (Wnt1, 3, 7b, 16) and Wnt target genes (Wisp1, Lef1) in aged hearts, which correlated with increased protein levels of β-Catenin. Cardiac fibroblasts lacking endogenous sFRP-1 showed increased αSMA expression, higher cell proliferation rates and increased collagen production consistent with the cardiac phenotype exhibited in aged sFRP-1 KO mice. The clinical relevance of these findings was supported by the demonstration of decreased sFRP-1 gene expression and increased Wisp-1 levels in the left ventricles of patients with ischemic dilated cardiomyopathy (ICM) and dilated cardiomyopathy (DCM). Conclusions This study identifies a novel role for sFRP-1 in age-related cardiac deterioration and fibrosis. Further exploration of this pathway will identify downstream molecules important in these processes and also suggest the potential use of Wnt signaling agents as therapeutic targets for age-related cardiovascular disorders in humans.