Altered Integrin Alpha 6 Expression As A Rescue For Muscle Fiber Detachment In Zebrafish (Danio Rerio)

Cells adhere to their extracellular matrix by way of integrins, transmembrane molecules that attach the cytoskeleton to the extracellular basement membrane (one kind of extracellular matrix). In some muscular dystrophies, specific integrins are disrupted and muscle fibers detach from the myotendenous junction and degenerate. This integrin disruption causes a constant cycle of regeneration and degeneration, which greatly harms the tissue over time. Congenital muscular dystrophy affects the integrin alpha 7 gene and prevents the muscle cell from producing the affiliated protein. In an attempt to rescue integrin alpha 7 dystrophies, this project over-expressed another integrin, integrin alpha 6, in zebrafish (Danio rerio). Preliminary data suggest it is possible to prevent fiber detachments in muscle, a characteristic of dystrophy, by over-expressing integrin alpha 6 in zebrafish lacking integrin alpha 7. Furthermore, a limited number of embryos, with both integrin alpha 7 and dystroglycan 1 deficiencies, show improved muscle structure when over-expressing the integrin alpha 6 protein. The integrin alpha 6 protein may hold promise for gene therapy applications because it already exists within the muscle fibers, reducing the risk of immunorejection. This protein may serve a useful therapeutic purpose if it can be both expressed uniformly and effectively in human skeletal muscle

miR-199b, a novel tumor suppressor miRNA in acute myeloid leukemia with prognostic implications

Additional file 1: Figure S1. miR-199b-5p targets HIF-1 alpha. Transcript levels of three predicted targets of miR-199b were tested via RT-qPCR in miR-199b silenced CD34 cells and HIF-1a levels were significantly increased by anti-miR-199b

Mitochondrial Reactive Oxygen Species in Lipotoxic Hearts Induces Post-Translational Modifications of AKAP121, DRP1 and OPA1 That Promote Mitochondrial Fission

Rationale: Cardiac lipotoxicity, characterized by increased uptake, oxidation and accumulation of lipid intermediates, contributes to cardiac dysfunction in obesity and diabetes. However, mechanisms linking lipid overload and mitochondrial dysfunction are incompletely understood. Objective: To elucidate the mechanisms for mitochondrial adaptations to lipid overload in postnatal hearts in vivo. Methods and Results: Using a transgenic mouse model of cardiac lipotoxicity overexpressing long-chain acyl-CoA synthetase 1 in cardiomyocytes, we show that modestly increased myocardial fatty acid uptake leads to mitochondrial structural remodeling with significant reduction in minimum diameter. This is associated with increased palmitoyl-carnitine oxidation and increased reactive oxygen species (ROS) generation in isolated mitochondria. Mitochondrial morphological changes and elevated ROS generation are also observed in palmitate- treated neonatal rat ventricular cardiomyocytes (NRVCs). Palmitate exposure to NRVCs initially activates mitochondrial respiration, coupled with increased mitochondrial membrane potential and adenosine triphosphate (ATP) synthesis. However, long-term exposure to palmitate (\u3e8h) enhances ROS generation, which is accompanied by loss of the mitochondrial reticulum and a pattern suggesting increased mitochondrial fission. Mechanistically, lipid-induced changes in mitochondrial redox status increased mitochondrial fission by increased ubiquitination of A-kinase anchor protein (AKAP121) leading to reduced phosphorylation of DRP1 at Ser637 and altered proteolytic processing of OPA1. Scavenging mitochondrial ROS restored mitochondrial morphology in vivo and in vitro. Conclusions: Our results reveal a molecular mechanism by which lipid overload-induced mitochondrial ROS generation causes mitochondrial dysfunction by inducing post-translational modifications of mitochondrial proteins that regulate mitochondrial dynamics. These findings provide a novel mechanism for mitochondrial dysfunction in lipotoxic cardiomyopathy. 38 pp; includes supplemental materials

Novel roles for podocalyxin in regulating stress myelopoiesis, Rap1a, and neutrophil migration.

Podocalyxin (Podxl) is a CD34 orthologue and cell surface sialomucin reported to have roles in renal podocyte diaphragm slit development; vascular cell integrity; and the progression of blood, breast, and prostate cancers. Roles for Podxl during nonmalignant hematopoiesis, however, are largely undefined. We have developed a Vav-Cre Podxl knockout (KO) mouse model, and report on novel roles for Podxl in governing stress myelopoiesis. At steady state, Podxl expression among hematopoietic progenitor cells was low level but was induced by granulocyte colony-stimulating factor (G-CSF) in myeloid progenitors and by thrombopoietin in human stem cells. In keeping with low-level Podxl expression at steady state, Vav-Cre deletion of Podxl did not markedly alter peripheral blood cell levels. A G-CSF challenge in Podxl-KO mice, in contrast, hyperelevated peripheral blood neutrophil and monocyte levels. Podxl-KO also substantially heightened neutrophil levels after 5-fluorouracil myeloablation. These loss-of-function phenotypes were selective, and Podxl-KO did not alter lymphocyte, basophil, or eosinophil levels. Within bone marrow (and after G-CSF challenge), Podxl deletion moderately decreased colony forming units-granulocytes, eyrthrocytes, monocyte/macrophages, megakaryocytes and CD16/3

Mitochondrial Reactive Oxygen Species in Lipotoxic Hearts Induces Post-Translational Modifications of AKAP121, DRP1 and OPA1 That Promote Mitochondrial Fission

Rationale: Cardiac lipotoxicity, characterized by increased uptake, oxidation and accumulation of lipid intermediates, contributes to cardiac dysfunction in obesity and diabetes. However, mechanisms linking lipid overload and mitochondrial dysfunction are incompletely understood. Objective: To elucidate the mechanisms for mitochondrial adaptations to lipid overload in postnatal hearts in vivo. Methods and Results: Using a transgenic mouse model of cardiac lipotoxicity overexpressing long-chain acyl-CoA synthetase 1 in cardiomyocytes, we show that modestly increased myocardial fatty acid uptake leads to mitochondrial structural remodeling with significant reduction in minimum diameter. This is associated with increased palmitoyl-carnitine oxidation and increased reactive oxygen species (ROS) generation in isolated mitochondria. Mitochondrial morphological changes and elevated ROS generation are also observed in palmitate- treated neonatal rat ventricular cardiomyocytes (NRVCs). Palmitate exposure to NRVCs initially activates mitochondrial respiration, coupled with increased mitochondrial membrane potential and adenosine triphosphate (ATP) synthesis. However, long-term exposure to palmitate (\u3e8h) enhances ROS generation, which is accompanied by loss of the mitochondrial reticulum and a pattern suggesting increased mitochondrial fission. Mechanistically, lipid-induced changes in mitochondrial redox status increased mitochondrial fission by increased ubiquitination of A-kinase anchor protein (AKAP121) leading to reduced phosphorylation of DRP1 at Ser637 and altered proteolytic processing of OPA1. Scavenging mitochondrial ROS restored mitochondrial morphology in vivo and in vitro. Conclusions: Our results reveal a molecular mechanism by which lipid overload-induced mitochondrial ROS generation causes mitochondrial dysfunction by inducing post-translational modifications of mitochondrial proteins that regulate mitochondrial dynamics. These findings provide a novel mechanism for mitochondrial dysfunction in lipotoxic cardiomyopathy. 38 pp; includes supplemental materials