SERCA2a overexpression improves muscle function in a canine Duchenne muscular dystrophy model.

Excessive cytosolic calcium accumulation contributes to muscle degeneration in Duchenne muscular dystrophy (DMD). Sarco/endoplasmic reticulum calcium ATPase (SERCA) is a sarcoplasmic reticulum (SR) calcium pump that actively transports calcium from the cytosol into the SR. We previously showed that adeno-associated virus (AAV)-mediated SERCA2a therapy reduced cytosolic calcium overload and improved muscle and heart function in the murine DMD model. Here, we tested whether AAV SERCA2a therapy could ameliorate muscle disease in the canine DMD model. 7.83 × 1013 vector genome particles of the AAV vector were injected into the extensor carpi ulnaris (ECU) muscles of four juvenile affected dogs. Contralateral ECU muscles received excipient. Three months later, we observed widespread transgene expression and significantly increased SERCA2a levels in the AAV-injected muscles. Treatment improved SR calcium uptake, significantly reduced calpain activity, significantly improved contractile kinetics, and significantly enhanced resistance to eccentric contraction-induced force loss. Nonetheless, muscle histology was not improved. To evaluate the safety of AAV SERCA2a therapy, we delivered the vector to the ECU muscle of adult normal dogs. We achieved strong transgene expression without altering muscle histology and function. Our results suggest that AAV SERCA2a therapy has the potential to improve muscle performance in a dystrophic large mammal.

Improved mitochondrial function in the hearts of sarcolipin-deficient dystrophin and utrophin double-knockout mice.

Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease associated with cardiomyopathy. DMD cardiomyopathy is characterized by abnormal intracellular Ca2+ homeostasis and mitochondrial dysfunction. We used dystrophin and utrophin double-knockout (mdx:utrn-/-) mice in a sarcolipin (SLN) heterozygous-knockout (sln+/-) background to examine the effect of SLN reduction on mitochondrial function in the dystrophic myocardium. Germline reduction of SLN expression in mdx:utrn-/- mice improved cardiac sarco/endoplasmic reticulum (SR) Ca2+ cycling, reduced cardiac fibrosis, and improved cardiac function. At the cellular level, reducing SLN expression prevented mitochondrial Ca2+ overload, reduced mitochondrial membrane potential loss, and improved mitochondrial function. Transmission electron microscopy of myocardial tissues and proteomic analysis of mitochondria-associated membranes showed that reducing SLN expression improved mitochondrial structure and SR-mitochondria interactions in dystrophic cardiomyocytes. These findings indicate that SLN upregulation plays a substantial role in the pathogenesis of cardiomyopathy and that reducing SLN expression has clinical implications in the treatment of DMD cardiomyopathy.

Neurotransmitter signaling specifies sweat gland stem cell fate through SLN-mediated intracellular calcium regulation.

Sympathetic nerves co-develop with their target organs and release neurotransmitters to stimulate their functions after maturation. Here, we provide the molecular mechanism that during sweat gland morphogenesis, neurotransmitters released from sympathetic nerves act first to promote sweat duct elongation via norepinephrine and followed by acetylcholine to specify sweat gland stem cell fate, which matches the sequence of neurotransmitter switch. Without neuronal signals during development, the basal cells switch to exhibit suprabasal (luminal) cell features. Sarcolipin (SLN), a key regulator of sarcoendoplasmic reticulum (SR) Ca 2+ -ATPase (SERCA), expression is significantly down-regulated in the sweat gland myoepithelial cells upon denervation. Loss of SLN in sweat gland myoepithelial cells leads to decreased intracellular Ca 2+ over time in response to ACh stimulation, as well as upregulation of luminal cell features. In cell culture experiments, we showed that contrary to the paradigm that elevation of Ca 2+ promote epidermal differentiation, specification of the glandular myoepithelial (basal) cells requires high Ca 2+ while lowering Ca 2+ level promotes luminal (suprabasal) cell fate. Our work highlights that neuronal signals not only act transiently for mature sweat glands to function, but also exert long-term impact on glandular stem cell specification through regulating intracellular Ca 2+ dynamics.

Distinct Roles of DRP1 in Conventional and Alternative Mitophagy in Obesity Cardiomyopathy.

BACKGROUND: Obesity induces cardiomyopathy characterized by hypertrophy and diastolic dysfunction. Whereas mitophagy mediated through an Atg7 (autophagy related 7)-dependent mechanism serves as an essential mechanism to maintain mitochondrial quality during the initial development of obesity cardiomyopathy, Rab9 (Ras-related protein Rab-9A)-dependent alternative mitophagy takes over the role during the chronic phase. Although it has been postulated that DRP1 (dynamin-related protein 1)-mediated mitochondrial fission and consequent separation of the damaged portions of mitochondria are essential for mitophagy, the involvement of DRP1 in mitophagy remains controversial. We investigated whether endogenous DRP1 is essential in mediating the 2 forms of mitophagy during high-fat diet (HFD)-induced obesity cardiomyopathy and, if so, what the underlying mechanisms are. METHODS: Mice were fed either a normal diet or an HFD (60 kcal %fat). Mitophagy was evaluated using cardiac-specific Mito-Keima mice. The role of DRP1 was evaluated using tamoxifen-inducible cardiac-specific Drp1knockout (Drp1 MCM) mice. RESULTS: Mitophagy was increased after 3 weeks of HFD consumption. The induction of mitophagy by HFD consumption was completely abolished in Drp1 MCM mouse hearts, in which both diastolic and systolic dysfunction were exacerbated. The increase in LC3 (microtubule-associated protein 1 light chain 3)-dependent general autophagy and colocalization between LC3 and mitochondrial proteins was abolished in Drp1 MCM mice. Activation of alternative mitophagy was also completely abolished in Drp1 MCM mice during the chronic phase of HFD consumption. DRP1 was phosphorylated at Ser616, localized at the mitochondria-associated membranes, and associated with Rab9 and Fis1 (fission protein 1) only during the chronic, but not acute, phase of HFD consumption. CONCLUSIONS: DRP1 is an essential factor in mitochondrial quality control during obesity cardiomyopathy that controls multiple forms of mitophagy. Although DRP1 regulates conventional mitophagy through a mitochondria-associated membrane-independent mechanism during the acute phase, it acts as a component of the mitophagy machinery at the mitochondria-associated membranes in alternative mitophagy during the chronic phase of HFD consumption.

Defective excitation-contraction coupling and mitochondrial respiration precede mitochondrial Ca2+ accumulation in spinobulbar muscular atrophy skeletal muscle.

Polyglutamine expansion in the androgen receptor (AR) causes spinobulbar muscular atrophy (SBMA). Skeletal muscle is a primary site of toxicity; however, the current understanding of the early pathological processes that occur and how they unfold during disease progression remains limited. Using transgenic and knock-in mice and patient-derived muscle biopsies, we show that SBMA mice in the presymptomatic stage develop a respiratory defect matching defective expression of genes involved in excitation-contraction coupling (ECC), altered contraction dynamics, and increased fatigue. These processes are followed by stimulus-dependent accumulation of calcium into mitochondria and structural disorganization of the muscle triads. Deregulation of expression of ECC genes is concomitant with sexual maturity and androgen raise in the serum. Consistent with the androgen-dependent nature of these alterations, surgical castration and AR silencing alleviate the early and late pathological processes. These observations show that ECC deregulation and defective mitochondrial respiration are early but reversible events followed by altered muscle force, calcium dyshomeostasis, and dismantling of triad structure.

Dwarf Open Reading Frame (DWORF) Gene Therapy Ameliorated Duchenne Muscular Dystrophy Cardiomyopathy in Aged mdx Mice.

Background Cardiomyopathy is a leading health threat in Duchenne muscular dystrophy (DMD). Cytosolic calcium upregulation is implicated in DMD cardiomyopathy. Calcium is primarily removed from the cytosol by the sarcoendoplasmic reticulum calcium ATPase (SERCA). SERCA activity is reduced in DMD. Improving SERCA function may treat DMD cardiomyopathy. Dwarf open reading frame (DWORF) is a recently discovered positive regulator for SERCA, hence, a potential therapeutic target. Methods and Results To study DWORF's involvement in DMD cardiomyopathy, we quantified DWORF expression in the heart of wild-type mice and the mdx model of DMD. To test DWORF gene therapy, we engineered and characterized an adeno-associated virus serotype 9-DWORF vector. To determine if this vector can mitigate DMD cardiomyopathy, we delivered it to 6-week-old mdx mice (6×1012 vector genome particles/mouse) via the tail vein. Exercise capacity, heart histology, and cardiac function were examined at 18 months of age. We found DWORF expression was significantly reduced at the transcript and protein levels in mdx mice. Adeno-associated virus serotype 9-DWORF vector significantly enhanced SERCA activity. Systemic adeno-associated virus serotype 9-DWORF therapy reduced myocardial fibrosis and improved treadmill running, electrocardiography, and heart hemodynamics. Conclusions Our data suggest that DWORF deficiency contributes to SERCA dysfunction in mdx mice and that DWORF gene therapy holds promise to treat DMD cardiomyopathy.

Reducing sarcolipin expression improves muscle metabolism in mdx mice.

Duchenne muscular dystrophy (DMD) is an inherited muscle wasting disease. Metabolic impairments and oxidative stress are major secondary mechanisms that severely worsen muscle function in DMD. Here, we sought to determine whether germline reduction or ablation of sarcolipin (SLN), an inhibitor of sarco/endoplasmic reticulum (SR) Ca2+ ATPase (SERCA), improves muscle metabolism and ameliorates muscle pathology in the mdx mouse model of DMD. Glucose and insulin tolerance tests show that glucose clearance rate and insulin sensitivity were improved in the SLN haploinsufficient mdx (mdx:sln+/-) and SLN-deficient mdx (mdx:sln-/-) mice. The histopathological analysis shows that fibrosis and necrosis were significantly reduced in muscles of mdx:sln+/- and mdx:sln-/- mice. SR Ca2+ uptake, mitochondrial complex protein levels, complex activities, mitochondrial Ca2+ uptake and release, and mitochondrial metabolism were significantly improved, and lipid peroxidation and protein carbonylation were reduced in the muscles of mdx:sln+/- and mdx:sln-/- mice. These data demonstrate that reduction or ablation of SLN expression can improve muscle metabolism, reduce oxidative stress, decrease muscle pathology, and protects the mdx mice from glucose intolerance.

AAV-mediated YAP expression in cardiac fibroblasts promotes inflammation and increases fibrosis.

Fibrosis is a hallmark of heart disease independent of etiology and is thought to contribute to impaired cardiac dysfunction and development of heart failure. However, the underlying mechanisms that regulate the differentiation of fibroblasts to myofibroblasts and fibrotic responses remain incompletely defined. As a result, effective treatments to mitigate excessive fibrosis are lacking. We recently demonstrated that the Hippo pathway effector Yes-associated protein (YAP) is an important mediator of myofibroblast differentiation and fibrosis in the infarcted heart. Yet, whether YAP activation in cardiac fibroblasts is sufficient to drive fibrosis, and how fibroblast YAP affects myocardial inflammation, a significant component of adverse cardiac remodeling, are largely unknown. In this study, we leveraged adeno-associated virus (AAV) to target cardiac fibroblasts and demonstrate that chronic YAP expression upregulated indices of fibrosis and inflammation in the absence of additional stress. YAP occupied the Ccl2 gene and promoted Ccl2 expression, which was associated with increased macrophage infiltration, pro-inflammatory cytokine expression, collagen deposition, and cardiac dysfunction in mice with cardiac fibroblast-targeted YAP overexpression. These results are consistent with other recent reports and extend our understanding of YAP function in modulating fibrotic and inflammatory responses in the heart.

Abnormal Calcium Handling in Duchenne Muscular Dystrophy: Mechanisms and Potential Therapies.

Duchenne muscular dystrophy (DMD) is an X-linked muscle-wasting disease caused by the loss of dystrophin. DMD is associated with muscle degeneration, necrosis, inflammation, fatty replacement, and fibrosis, resulting in muscle weakness, respiratory and cardiac failure, and premature death. There is no curative treatment. Investigations on disease-causing mechanisms offer an opportunity to identify new therapeutic targets to treat DMD. An abnormal elevation of the intracellular calcium ( Ca i 2 + ) concentration in the dystrophin-deficient muscle is a major secondary event, which contributes to disease progression in DMD. Emerging studies have suggested that targeting Ca2+-handling proteins and/or mechanisms could be a promising therapeutic strategy for DMD. Here, we provide an updated overview of the mechanistic roles the sarcolemma, sarcoplasmic/endoplasmic reticulum, and mitochondria play in the abnormal and sustained elevation of Ca i 2 + levels and their involvement in DMD pathogenesis. We also discuss current approaches aimed at restoring Ca2+ homeostasis as potential therapies for DMD.

Sarcolipin haploinsufficiency prevents dystrophic cardiomyopathy in mdx mice.

Sarcolipin (SLN) is an inhibitor of sarco/endoplasmic reticulum (SR) Ca2+-ATPase (SERCA) and expressed at high levels in the ventricles of animal models for and patients with Duchenne muscular dystrophy (DMD). The goal of this study was to determine whether the germline ablation of SLN expression improves cardiac SERCA function and intracellular Ca2+ (Ca2+i) handling and prevents cardiomyopathy in the mdx mouse model of DMD. Wild-type, mdx, SLN-haploinsufficient mdx (mdx:sln+/-), and SLN-deficient mdx (mdx:sln-/-) mice were used for this study. SERCA function and Ca2+i handling were determined by Ca2+ uptake assays and by measuring single-cell Ca2+ transients, respectively. Age-dependent disease progression was determined by histopathological examinations and by echocardiography in 6-, 12-, and 20-mo-old mice. Gene expression changes in the ventricles of mdx:sln+/- mice were determined by RNA-Seq analysis. SERCA function and Ca2+i cycling were improved in the ventricles of mdx:sln+/- mice. Fibrosis and necrosis were significantly decreased, and cardiac function was enhanced in the mdx:sln+/- mice until the study endpoint. The mdx:sln-/- mice also exhibited similar beneficial effects. RNA-Seq analysis identified distinct gene expression changes including the activation of the apelin pathway in the ventricles of mdx:sln+/- mice. Our findings suggest that reducing SLN expression is sufficient to improve cardiac SERCA function and Ca2+i cycling and prevent cardiomyopathy in mdx mice.NEW & NOTEWORTHY First, reducing sarcopolin (SLN) expression improves sarco/endoplasmic reticulum Ca2+ uptake and intracellular Ca2+ handling and prevents cardiomyopathy in mdx mice. Second, reducing SLN expression prevents diastolic dysfunction and improves cardiac contractility in mdx mice Third, reducing SLN expression activates apelin-mediated cardioprotective signaling pathways in mdx heart.

In silico analysis of new flavonoids from Pongamia pinnata with a therapeutic potential for age-related macular degeneration.

Age-related macular degeneration (AMD) leads to progressive degeneration of the macula which ultimately results in the complete loss of central vision. The present study aims to identify the new therapeutic agents for curing AMD. In the present study we have isolated, and compared the activity of natural flavonoids (Karanjin, Karanjachromene, Pongachromene, Pongapin) from plant species Pongamia pinnata (L.) Pierre (Family: Fabaceae) with known flavonol, Quercetin, and a drug Pazopanib through in silico approaches. Chemical structures of isolated flavonoids passed the ADME and PASS analysis, showed drug-like properties without violation of Lipinski parameters. Molecular docking studies were also performed for all isolated flavonoids with the receptors responsible for AMD viz. P2X7, PPAR, RAGE, and TLR3. Docking scores of the flavonoids with the receptors were found to be comparable to that of Quercetin, and Pazopanib (drugs already known for AMD treatment). Among all the flavonoids, Karanjachromene [P2X7 (- 31.39)] and Pongachromene [PPAR (- 65.13), RAGE (- 43.42)] showed a very good binding affinity with receptors predicting them to be the new potent chemical entities for the treatment of AMD.

Single SERCA2a Therapy Ameliorated Dilated Cardiomyopathy for 18 Months in a Mouse Model of Duchenne Muscular Dystrophy.

Loss of dystrophin leads to Duchenne muscular dystrophy (DMD). A pathogenic feature of DMD is the significant elevation of cytosolic calcium. Supraphysiological calcium triggers protein degradation, membrane damage, and eventually muscle death and dysfunction. Sarcoplasmic/endoplasmic reticulum (SR) calcium ATPase (SERCA) is a calcium pump that transports cytosolic calcium to the SR during excitation-contraction coupling. We hypothesize that a single systemic delivery of SERCA2a with adeno-associated virus (AAV) may improve calcium recycling and provide long-lasting benefits in DMD. To test this, we injected an AAV9 human SERCA2a vector (6 × 1012 viral genome particles/mouse) intravenously to 3-month-old mdx mice, the most commonly used DMD model. Immunostaining and western blot showed robust human SERCA2a expression in the heart and skeletal muscle for 18 months. Concomitantly, SR calcium uptake was significantly improved in these tissues. SERCA2a therapy significantly enhanced grip force and treadmill performance, completely prevented myocardial fibrosis, and normalized electrocardiograms (ECGs). Cardiac catheterization showed normalization of multiple systolic and diastolic hemodynamic parameters in treated mice. Importantly, chamber dilation was completely prevented, and ejection fraction was restored to the wild-type level. Our results suggest that a single systemic AAV9 SERCA2a therapy has the potential to provide long-lasting benefits for DMD.

Does potassium iodide application following silver diamine fluoride reduce staining of tooth? A systematic review.

OBJECTIVES: To assess if using potassium iodide (KI) immediately after application of silver diamine fluoride (SDF) significantly reduces the staining of tooth structure. DATA SOURCE AND SELECTION: Four online databases (OVID, Scopus, PubMed and Google Scholar) were searched (June 2019). Additional studies were sought through grey literature search and hand searching the reference list of included articles. All studies that analysed the effect of KI on SDF staining of tooth structure with access to full text in English language were included. DATA SYNTHESIS: Of the six articles included in the review, five reported stain reduction in the teeth treated with application of KI to carious tooth structure following the application of SDF while one article reported no significant beneficial effect on reducing staining, when compared to SDF alone. Of the materials selected to restore SDF + KI treated teeth, resin-modified glass ionomer was found to produce the lightest results, followed by glass ionomer cement and composite resin. An in vivo case report also revealed some staining after six months, even with SDF + KI treatment. CONCLUSIONS: Although some studies reported a positive effect, insufficient evidence exists supporting a tangible clinical benefit of SDF + KI treatment on the tooth staining, mainly due to methodical variations within the current literature.

Sarcolipin overexpression impairs myogenic differentiation in Duchenne muscular dystrophy.

Reduction in the expression of sarcolipin (SLN), an inhibitor of sarco(endo)plasmic reticulum (SR) Ca2+-ATPase (SERCA), ameliorates severe muscular dystrophy in mice. However, the mechanism by which SLN inhibition improves muscle structure remains unclear. Here, we describe the previously unknown function of SLN in muscle differentiation in Duchenne muscular dystrophy (DMD). Overexpression of SLN in C2C12 resulted in decreased SERCA pump activity, reduced SR Ca2+ load, and increased intracellular Ca2+ (Cai2+) concentration. In addition, SLN overexpression resulted in altered expression of myogenic markers and poor myogenic differentiation. In dystrophin-deficient dog myoblasts and myotubes, SLN expression was significantly high and associated with defective Cai2+ cycling. The dystrophic dog myotubes were less branched and associated with decreased autophagy and increased expression of mitochondrial fusion and fission proteins. Reduction in SLN expression restored these changes and enhanced dystrophic dog myoblast fusion during differentiation. In summary, our data suggest that SLN upregulation is an intrinsic secondary change in dystrophin-deficient myoblasts and could account for the Cai2+ mishandling, which subsequently contributes to poor myogenic differentiation. Accordingly, reducing SLN expression can improve the Cai2+ cycling and differentiation of dystrophic myoblasts. These findings provide cellular-level supports for targeting SLN expression as a therapeutic strategy for DMD.

Role of nitric oxide-scavenging activity of Karanjin and Pongapin in the treatment of Psoriasis.

In the present study, Karanjin and Pongapin, two important furanoflavone, constituents of Pongamia pinnata were studied in the management of Psoriasis. Presently, we have experimentally studied the free radical quenching property of Karanjin and Pongapin. A modified method was used to estimate the scavenging effect of the Karanjin (the highest activity of 95.60%) and Pongapin (68.05%) compared to the ascorbic acid as standard (11.60%) against nitric oxide. Furthermore, Molecular docking studies were performed using CLC drug discovery workbench software version 3.0 of the studied flavones (Karanjin and Pongapin) with the receptors responsible for psoriasis (viz. IL-17A, IL-17F, IL-23, RORγt, and TLR-7). Docking scores of Karanjin and Pongapin with different studied receptors were found to be comparable to that of Methotrexate, a known drug for treating Psoriasis. Docking results suggest that Karanjin and Pongapin might also help in controlling the disease. Overall, our results indicate that flavones (Karanjin and Pongapin) could be a natural and better alternative in curing psoriasis without any side effects.

Reducing sarcolipin expression mitigates Duchenne muscular dystrophy and associated cardiomyopathy in mice.

Sarcolipin (SLN) is an inhibitor of the sarco/endoplasmic reticulum (SR) Ca2+ ATPase (SERCA) and is abnormally elevated in the muscle of Duchenne muscular dystrophy (DMD) patients and animal models. Here we show that reducing SLN levels ameliorates dystrophic pathology in the severe dystrophin/utrophin double mutant (mdx:utr -/-) mouse model of DMD. Germline inactivation of one allele of the SLN gene normalizes SLN expression, restores SERCA function, mitigates skeletal muscle and cardiac pathology, improves muscle regeneration, and extends the lifespan. To translate our findings into a therapeutic strategy, we knock down SLN expression in 1-month old mdx:utr -/- mice via adeno-associated virus (AAV) 9-mediated RNA interference. The AAV treatment markedly reduces SLN expression, attenuates muscle pathology and improves diaphragm, skeletal muscle and cardiac function. Taken together, our findings suggest that SLN reduction is a promising therapeutic approach for DMD.

Employment Status of Patients Receiving Maintenance Dialysis - Peritoneal and Hemodialysis: A Cross-sectional Study.

The long-term dialysis therapy for end-stage renal disease takes a heavy toll of quality of life of the patient. Several factors such as fatigue and decreased physical capability, impaired social and mental functioning, contribute to this forlorn state. To meld maintenance dialysis treatment with a regular employment can be a serious test. A cross-sectional study of employment of patients on hemodialysis and peritoneal dialysis in a state government tertiary institute in South India was performed between June 2015 and December 2015. Patients who completed 3 months of regular dialysis were only included in the study. The number of patients on hemodialysis was 157 and on peritoneal dialysis was 69. The employment status before the initiation of dialysis was 60% (93 out of 155) and 63.7% (44 out of 69) in hemodialysis and peritoneal dialysis, respectively. After initiation, the loss of employment was observed in 44% (41 out of 93) in hemodialysis and 51.2% (26 out of 44) in peritoneal dialysis (P = 0.2604). Even though there was fall of absolute number of job holders in both the blue and white collar jobs, the proportion of jobholders in the white collar job holders improved. On univariate analysis, the factors which influenced the loss of employment were males, age between 50 and 60 years, number of comorbidities >2, illiteracy and blue collar versus white collar job before the initiation of dialysis. The majority of patients had the scores above 80 on Karnofsky performance scale and the majority belonged upper and middle classes than lower classes on modified Kuppuswamy's socioeconomic status scale; however, the loss of employment was also disproportionately high. There appeared a substantial difference in the attitude of the patients toward the employment. There was no difference between hemodialysis and peritoneal dialysis in the loss of employment of our patients.

H-Ras Isoform Mediates Protection Against Pressure Overload-Induced Cardiac Dysfunction in Part Through Activation of AKT.

BACKGROUND: In general, Ras proteins are thought to promote cardiac hypertrophy, an important risk factor for cardiovascular disease and heart failure. However, the contribution of different Ras isoforms has not been investigated. The objective of this study was to define the role of H- and K-Ras in modulating stress-induced myocardial hypertrophy and failure. METHODS AND RESULTS: We used H- and K-Ras gene knockout mice and subjected them to pressure overload to induce cardiac hypertrophy and dysfunction. We observed a worsened cardiac phenotype in Hras-/- mice, while outcomes were improved in Kras+/- mice. We also used a neonatal rat cardiomyocyte culture system to elucidate the mechanisms underlying these observations. Our findings demonstrate that H-Ras, but not K-Ras, promotes cardiomyocyte hypertrophy both in vivo and in vitro. This response was mediated in part through the phosphoinositide 3-kinase-AKT signaling pathway. Adeno-associated virus-mediated increase in AKT activation improved the cardiac function in pressure overloaded Hras null hearts in vivo. These findings further support engagement of the phosphoinositide 3-kinase-AKT signaling axis by H-Ras. CONCLUSIONS: Taken together, these findings indicate that H- and K-Ras have divergent effects on cardiac hypertrophy and heart failure in response to pressure overload stress.

Sequence analysis of Indian iris yellow spot virus ambisense genome segments: evidence of interspecies RNA recombination.

The nucleotide sequence of M- and S-RNA segments of an Indian iris yellow spot virus (IYSV) were determined. Sequence comparisons showed that both of these sequences shared less than 95 % identity with those other known IYSV isolates. Phylogenetic analysis revealed that the S- and M-RNA sequences of known IYSV isolates clustered with those of the tospoviruses, tomato yellow ring virus, polygonum ringspot virus and hippeastrum chlorotic ringspot virus. Further, multiple recombination detection methods detected inter- and intra-species recombination events that clustered primarily within the intergenic regions of S- and M-RNA, suggesting that these are possibly recombination hotspots in IYSV and closely related tospoviruses.

Cardiac specific expression of threonine 5 to alanine mutant sarcolipin results in structural remodeling and diastolic dysfunction.

The functional importance of threonine 5 (T5) in modulating the activity of sarcolipin (SLN), a key regulator of sarco/endoplasmic reticulum (SR) Ca2+ ATPase (SERCA) pump was studied using a transgenic mouse model with cardiac specific expression of threonine 5 to alanine mutant SLN (SLNT5A). In these transgenic mice, the SLNT5A protein replaces the endogenous SLN in atria, while maintaining the total SLN content. The cardiac specific expression of SLNT5A results in severe cardiac structural remodeling accompanied by bi-atrial enlargement. Biochemical analyses reveal a selective downregulation of SR Ca2+ handling proteins and a reduced SR Ca2+ uptake both in atria and in the ventricles. Optical mapping analysis shows slower action potential propagation in the transgenic mice atria. Doppler echocardiography and hemodynamic measurements demonstrate a reduced atrial contractility and an impaired diastolic function. Together, these findings suggest that threonine 5 plays an important role in modulating SLN function in the heart. Furthermore, our studies suggest that alteration in SLN function can cause abnormal Ca2+ handling and subsequent cardiac remodeling and dysfunction.