Mutant KCNJ3 and KCNJ5 Potassium Channels as Novel Molecular Targets in Bradyarrhythmias and Atrial Fibrillation.

BACKGROUND: Bradyarrhythmia is a common clinical manifestation. Although the majority of cases are acquired, genetic analysis of families with bradyarrhythmia has identified a growing number of causative gene mutations. Because the only ultimate treatment for symptomatic bradyarrhythmia has been invasive surgical implantation of a pacemaker, the discovery of novel therapeutic molecular targets is necessary to improve prognosis and quality of life. METHODS: We investigated a family containing 7 individuals with autosomal dominant bradyarrhythmias of sinus node dysfunction, atrial fibrillation with slow ventricular response, and atrioventricular block. To identify the causative mutation, we conducted the family-based whole exome sequencing and genome-wide linkage analysis. We characterized the mutation-related mechanisms based on the pathophysiology in vitro. After generating a transgenic animal model to confirm the human phenotypes of bradyarrhythmia, we also evaluated the efficacy of a newly identified molecular-targeted compound to upregulate heart rate in bradyarrhythmias by using the animal model. RESULTS: We identified one heterozygous mutation, KCNJ3 c.247A>C, p.N83H, as a novel cause of hereditary bradyarrhythmias in this family. KCNJ3 encodes the inwardly rectifying potassium channel Kir3.1, which combines with Kir3.4 (encoded by KCNJ5) to form the acetylcholine-activated potassium channel ( IKACh channel) with specific expression in the atrium. An additional study using a genome cohort of 2185 patients with sporadic atrial fibrillation revealed another 5 rare mutations in KCNJ3 and KCNJ5, suggesting the relevance of both genes to these arrhythmias. Cellular electrophysiological studies revealed that the KCNJ3 p.N83H mutation caused a gain of IKACh channel function by increasing the basal current, even in the absence of m2 muscarinic receptor stimulation. We generated transgenic zebrafish expressing mutant human KCNJ3 in the atrium specifically. It is interesting to note that the selective IKACh channel blocker NIP-151 repressed the increased current and improved bradyarrhythmia phenotypes in the mutant zebrafish. CONCLUSIONS: The IKACh channel is associated with the pathophysiology of bradyarrhythmia and atrial fibrillation, and the mutant IKACh channel ( KCNJ3 p.N83H) can be effectively inhibited by NIP-151, a selective IKACh channel blocker. Thus, the IKACh channel might be considered to be a suitable pharmacological target for patients who have bradyarrhythmia with a gain-of-function mutation in the IKACh channel.

Branched-chain amino acids prevent hepatic fibrosis and development of hepatocellular carcinoma in a non-alcoholic steatohepatitis mouse model.

Oral supplementation with branched-chain amino acids (BCAA; leucine, isoleucine, and valine) in patients with liver cirrhosis potentially suppresses the incidence of hepatocellular carcinoma (HCC) and improves event-free survival. However, the detailed mechanisms of BCAA action have not been fully elucidated. BCAA were administered to atherogenic and high-fat (Ath+HF) diet-induced nonalcoholic steatohepatitis (NASH) model mice. Liver histology, tumor incidence, and gene expression profiles were evaluated. Ath+HF diet mice developed hepatic tumors at a high frequency at 68 weeks. BCAA supplementation significantly improved hepatic steatosis, inflammation, fibrosis, and tumors in Ath+HF mice at 68 weeks. GeneChip analysis demonstrated the significant resolution of pro-fibrotic gene expression by BCAA supplementation. The anti-fibrotic effect of BCAA was confirmed further using platelet-derived growth factor C transgenic mice, which develop hepatic fibrosis and tumors. In vitro, BCAA restored the transforming growth factor (TGF)-ß1-stimulated expression of pro-fibrotic genes in hepatic stellate cells (HSC). In hepatocytes, BCAA restored TGF-ß1-induced apoptosis, lipogenesis, and Wnt/ß-Catenin signaling, and inhibited the transformation of WB-F344 rat liver epithelial stem-like cells. BCAA repressed the promoter activity of TGFß1R1 by inhibiting the expression of the transcription factor NFY and histone acetyltransferase p300. Interestingly, the inhibitory effect of BCAA on TGF-ß1 signaling was mTORC1 activity-dependent, suggesting the presence of negative feedback regulation from mTORC1 to TGF-ß1 signaling. Thus, BCAA induce an anti-fibrotic effect in HSC, prevent apoptosis in hepatocytes, and decrease the incidence of HCC; therefore, BCAA supplementation would be beneficial for patients with advanced liver fibrosis with a high risk of HCC.

Dietary Flavonoid Hyperoside Induces Apoptosis of Activated Human LX-2 Hepatic Stellate Cell by Suppressing Canonical NF-κB Signaling.

Hyperoside, an active compound found in plants of the genera Hypericum and Crataegus, is reported to exhibit antioxidant, anticancer, and anti-inflammatory activities. Induction of hepatic stellate cell (HSC) apoptosis is recognized as a promising strategy for attenuation of hepatic fibrosis. In this study, we investigated whether hyperoside treatment can exert antifibrotic effects in human LX-2 hepatic stellate cells. We found that hyperoside induced apoptosis in LX-2 cells and decreased levels of α-smooth muscle actin (α-SMA), type I collagen, and intracellular reactive oxygen species (ROS). Remarkably, hyperoside also inhibited the DNA-binding activity of the transcription factor NF-κB and altered expression levels of NF-κB-regulated genes related to apoptosis, including proapoptotic genes Bcl-Xs, DR4, Fas, and FasL and anti-apoptotic genes A20, c-IAP1, Bcl-X L , and RIP1. Our results suggest that hyperoside may have potential as a therapeutic agent for the treatment of liver fibrosis.

Unrelated donor hematopoietic stem cell transplantation for the treatment of non-malignant genetic diseases: An alemtuzumab based regimen is associated with cure of clinical disease; earlier clearance of alemtuzumab may be associated with graft rejection.

Hematopoietic stem cell transplantation (HSCT) with matched unrelated donors (MUD), offers potentially curative therapy for patients with non-malignant genetic diseases. In this pilot study conducted from 2006 to 2014, we report the outcomes of 15 patients with non-malignant genetic diseases who received a myeloablative regimen with a reduced cyclophosphamide dose, adjunctive serotherapy and MUD HSCT [intravenous alemtuzumab (52 mg/m(2) ), busulfan (16 mg/kg), fludarabine (140mg/m(2) ), and cyclophosphamide (105 mg/kg)]. Graft-versus-host-disease (GVHD) prophylaxis consisted of tacrolimus/cyclosporine and methylprednisolone. Median (range) time to neutrophil engraftment (>500 cells/µL) and platelet engraftment (>20,000/mm(3) ) were 15 (12-28) and 25 (17-30) days, respectively. At a median follow-up of 2 (0.2-5.4) years, the overall survival (OS) was 93.3% (95% CI: 0.61-0.99) and disease-free survival (DFS) was 73.3% (95% CI: 0.44-0.89). Among this small sample, earlier alemtuzumab clearance was significantly associated with graft rejection (P = 0.047), earlier PHA response (P = 0.009) and a trend toward earlier recovery of recent thymic emigrants (RTE) (P = 0.06). This regimen was associated with durable donor engraftment and relatively low rates of regimen related toxicity (RRT); future alemtuzumab pharmacokinetic studies may improve outcomes, by allowing targeted alemtuzumab clearance to reduce graft rejection and promote more rapid immune reconstitution.

Thyroid volume, iodine intake, autoimmune thyroid disorders, inborn factors, and endocrine disruptors: twenty-year studies of multiple effects puzzle in Slovakia.

OBJECTIVE: The aim of this study was to evaluate multiple interrelations between several endogenous and exogenous effects and the thyroid volume and function in large groups of children, adolescents, and adults with a sufficient whole life intake of the iodine. SUBJECTS AND METHODS: The data were obtained either by cross sectioned or longitudinal studies in a total of 4998 children and adolescents (aged 7 to 17 years) and 2501 adults (1071 males and 1430 females aged 20-75 years). Thyroid volume (ThV) was measured by ultrasound, antibodies, and hormones by electrochemiluminiscent immunoassay, and endocrine disruptors (EDs, polychlorinated biphenyls-PCB, dichlorodiethyl-ichloroethylene-DDE, and hexachlorobenzene-HCB) by high resolution gas chromatography/mass spectrometry. RESULTS: 1. In large groups of boys and girls of age 7, 10, 13 or 17 years, the ThV was significantly higher in the 10th decile than in pooled nine lower deciles. Moreover, in 17-year old subjects significantly higher prevalence of hypoechogenicity by ultrasound, positive thyroperoxidase antibodies (TPOab), and increased thyrotropin (TSH) levels were found in the 10th decile. 2. In a small group of children, some individuals revealed consistently higher ThV during the whole 7-year follow-up period irrespective of supplementation with iodine. 3. In 325 sibling pairs of age 10-19 years, born within three years, three groups with different ThV/m2 of body surface were distinguished: Group A (183 pairs having both ThVs small), Group B (103 pairs having both ThVs large); Group C (33 pairs having one ThV small and the other one large). Similar aggregation of ThVs in three groups was observed in 13 pairs of discordant twins and 19 sibling triads in which all the siblings were born within four years. 4. In 42 concordant twins, several pairs had ThV nearly twice as high (in terms of both plain ThV or ThV/m2 of the body surface) as several other pairs of the same age which is assumed to be a result of a genetic background. 5. In large cohorts of males and females, a highly significant positive correlation was found between the ThV and high level of TPOab on one side and EDs on the other side. However, in nearly the same numbers of subjects with low TPOab, negative correlation was seen between ThV and disruptors. These observations may apparently support the synergic effect of the autoimmunity and EDs on the thyroid function. CONCLUSIONS: Several cases of an excessive thyroid growth in the iodine replenished children, adolescents, and adults may apparently result from the autoimmune thyroiditis, probably induced by immunogenic action of iodine in presumably disposed individuals. However, in some cases even simultaneous participation of EDs can not be excluded. Some observations have also suggested that excessive thyroid growth in the iodine replenished adolescent and adult population which was equally exposed to disruptors may also result from other reasons as the unfavorable hereditary background.

Toward a therapeutic strategy for polyalanine expansions disorders: in vivo and in vitro models for drugs analysis.

Molecular pathogenesis of congenital disorders associated with polyalanine expansions has been investigated for several years. Despite different pathological hallmarks characterize each polyalanine disease, they share common features, mainly represented by aggregates containing the mutant proteins, usually mislocated inside the cellular compartments, along with ubiquitin and proteasome components. Recently, particular interest has been raised by investigations on molecules able to restore both correct localization and function of the expanded proteins. Here we report a list of drugs whose effects have been assayed both in in vitro and in vivo models of polyalanine disorders, such as the oculopharyingeal muscular dystrophy, congenital central hypoventilation syndrome, synpolydactyly and in cell and animal models carrying specific artificial mutations. In particular, we have reviewed, for each polyalanine mutant protein, the molecules tested, cellular models under investigation, drugs effects on aggregation and underlying mechanisms.

Sanjad-Sakati syndrome in a neonate.

Congenital hypoparathyroidism, growth retardation and dysmorphism is a rare autosomal recessive syndrome among Arab population commonly known as Sanjad-Sakati syndrome(SSS).Several metabolic and septic complications are known to manifest in the neonatal age. We describe the first report of morbid pathological fractures affecting a neonate with SSS.

Natural history and treatment of peripheral inherited neuropathies.

Charcot-Marie-Tooth disease (CMT) is genetically highly heterogeneous. Disease course and severity vary according to CMT type, causative gene, and mutation type, but considerable phenotypic variability may occur also for the same CMT type. Research is focused on possible modifier factors particularly in CMT1A associated with Peripheral Myelin Protein 22 (PMP22) overexpression. Natural history studies are important to define disease course in different CMT types and to allow better assessment of intervention efficacy. Only a few such studies have been carried out, mainly on CMT1A, and described impairment and disability progression. Motor potential amplitudes seem to correlate with disease severity and progression, suggesting that axonal loss is the basis of disability in CMT. There is need to develop suitable and reproducible outcome measures: the CMT Neuropathy Score is the only validated outcome score specific for CMT, but others have been tested during the last few years. Currently there is no effective drug therapy for CMT and supportive treatment is limited to physical therapy, orthotics, surgical treatment of skeletal deformities and soft tissue abnormalities, and symptomatic drug treatment. Research is focused on developing new treatment strategies and approaches. The progesterone antagonist onapristone proved to be effective in a rat model of CMT1A; unfortunately, currently available progesterone antagonists are too toxic to be safely administered to patients. Neurotrophin-3 (NT3), a neurotrophic factor known to promote axonal growth, was tested with favourable results in two animal models and in a pilot study involving eight CMT1A patients. Ascorbic acid (AA) administration to CMT1A mice improved clinical and neuropathological findings, possibly by down-regulating PMP22 through a cAMP mediated mechanism. Clinical trials of AA in the human disease are currently being performed. Curcumin stimulates translocation of misfolded protein from the endoplasmic reticulum and proved useful for selected myelin protein zero and PMP22 mutants in vitro and in the animal models Trembler and TremblerJ.

Animal models of human disease: zebrafish swim into view.

Despite the pre-eminence of the mouse in modelling human disease, several aspects of murine biology limit its routine use in large-scale genetic and therapeutic screening. Many researchers who are interested in an embryologically and genetically tractable disease model have now turned to zebrafish. Zebrafish biology allows ready access to all developmental stages, and the optical clarity of embryos and larvae allow real-time imaging of developing pathologies. Sophisticated mutagenesis and screening strategies on a large scale, and with an economy that is not possible in other vertebrate systems, have generated zebrafish models of a wide variety of human diseases. This Review surveys the achievements and potential of zebrafish for modelling human diseases and for drug discovery and development.

Anemia, genetic diseases, and malaria in prehistoric mainland Southeast Asia.

The analysis of a sample of skeletons from the 4,000-year-old site of Khok Phanom Di on the coast of central Thailand has identified a number of individuals with skeletal evidence suggestive of severe anemia. The differential diagnosis of the lesions is discussed and the presence of one of the thalassemia syndromes is proposed. The implications of this for southeast Asian prehistory are discussed. The presence of these conditions has been suggested in previous analyses of prehistoric southeast Asian populations, but this is the first population in which the evidence, including postcranial responses, is presented in detail.

Antigenotoxic activity of carotenoids in carcinogen-exposed populations.

Although epidemiological studies suggest the presence of anticarcinogenic agents in the diet, it is difficult to obtain actual proof for the activity of such agents in humans. One approach is to develop and validate potential quantifiable indicators of antigenotoxic/anticarcinogenic agents which can be used in humans belonging to populations at elevated risk for cancer. This paper provides evidence that the exfoliated cell micronucleus test (MEC test) can be used (i) to provide a quantifiable marker for the amount of chromosomal breakage occurring in target tissues of carcinogen-exposed populations; (ii) to indicate the capacity of beta-carotene, alone or in combination with vitamin A, to prevent such damage; and (iii) to predict the response of other biological indicators of cancer risk, such as oral leukoplakias, in individuals receiving oral supplementation with beta-carotene/vitamin A (although the dose and time to response may differ for these endpoints). Future extensions of this approach include establishing the levels of beta-carotene required for antigenotoxic activity in a carcinogen's target tissue by concurrently measuring MEC frequencies and beta-carotene levels in exfoliated cells. In summary, early indications are that the MEC assay is an effective indicator for antigenotoxic agents in carcinogen-exposed individuals and that beta-carotene and vitamin A can suppress such genotoxic activity in at least some populations.