Browsing by Author "Bevilacqua, Jorge A."

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    Abnormal distribution of inositol 1,4,5-trisphosphate receptors in human muscle can be related to altered calcium signals and gene expression in Duchenne dystrophy-derived cells
    (FEDERATION AMER SOC EXP BIOL, 2010) Cardenas, Cesar; Juretic, Nevenka; Bevilacqua, Jorge A.; Garcia, Isaac E.; Figueroa, Reinaldo; Hartley, Ricardo; Taratuto, Ana L.; Gejman, Roger; Riveros, Nora; Molgo, Jordi; Jaimovich, Enrique
    Inositol 1,4,5-trisphosphate (IP3) receptors (IP(3)Rs) drive calcium signals involved in skeletal muscle excitation-transcription coupling and plasticity; IP3R subtype distribution and downstream events evoked by their activation have not been studied in human muscle nor has their possible alteration in Duchenne muscular dystrophy (DMD). We studied the expression and localization of IP3R subtypes in normal and DMD human muscle and in normal (RCMH) and dystrophic (RCDMD) human muscle cell lines. In normal muscle, both type 1 IP(3)Rs (IP(3)R1) and type 2 IP(3)Rs (IP(3)R2) show a higher expression in type II fibers, whereas type 3 IP(3)Rs (IP(3)R3) show uniform distribution. In DMD biopsies, all fibers display a homogeneous IP(3)R2 label, whereas 24 +/- 7% of type II fibers have lost the IP(3)R1 label. RCDMD cells show 5-fold overexpression of IP(3)R2 and down-regulation of IP(3)R3 compared with RCMH cells. A tetanic stimulus induces IP3-dependent slow Ca2+ transients significantly larger and faster in RCDMD cells than in RCMH cells as well as significant ERK1/2 phosphorylation in normal but not in dystrophic cells. Excitation-driven gene expression was different among cell lines; 44 common genes were repressed in RCMH cells and expressed in RCDMD cells or vice versa. IP3-dependent Ca2+ release may play a significant role in DMD pathophysiology.-Cardenas, C., Juretic, N., Bevilacqua, J. A., Garcia, I. E., Figueroa, R., Hartley, R., Taratuto, A. L., Gejman, R., Riveros, N., Molgo, J., Jaimovich, E. Abnormal distribution of inositol 1,4,5-trisphosphate receptors in human muscle can be related to altered calcium signals and gene expression in Duchenne dystrophy-derived cells. FASEB J. 24, 3210-3221 (2010). www.fasebj.org
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    Dysferlinopathy in Chile: Evidence of Two Novel Mutations in the First Reported Cases
    (MARY ANN LIEBERT, INC, 2009) Bevilacqua, Jorge A.; Krahn, Martin; Pedraza, Luis; Gejman, Roger; Gonzalez, Sergio; Levy, Nicolas
    We describe two Chilean patients with dysferlinopathy, a 32-year-old man with Miyoshi's distal myopathy and a 29-year-old woman with a proximodistal phenotype. Absence of dysferlin in frozen muscle biopsy allowed diagnostic confirmation. In these two patients, two mutations not previously identified in other populations were found: a homozygous c.1948delC (p. Leu650TyrfsX6) was found in the male patient; the heterozygous mutation c.1276G>A (p.Gly426Arg) was found in the female patient in association with the previously reported c.2858dupT (p.Phe954ValfsX2). To our knowledge, this is the first time that mutations in DYSF are identified in native Chileans. Our findings suggest the possibility that mutations in the DYSF gene were present in the Native American population before colonization.
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    MUSCLE MAGNETIC RESONANCE IMAGING AND HISTOPATHOLOGY IN ACTA1-RELATED CONGENITAL NEMALINE MYOPATHY
    (2014) Castiglioni, Claudia; Cassandrini, Denis; Fattori, Fabiana; Bellacchio, Emanuele; D'Amico, Adele; Alvarez, Karin; Gejman Enríquez, Roger; Diaz, Jorge; Santorelli, Filippo M.; Romero, Norma B.; Bertini, Enrico; Bevilacqua, Jorge A.
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    The absence of dysferlin induces the expression of functional connexin-based hemichannels in human myotubes
    (2016) Cea Pisani, Luis Andrés.; Sáez, Juan Carlos; Bevilacqua, Jorge A.; Arriagada, Christian.; Cárdenas, Ana M.; Bigot, Anne.; Mouly, Vincent.; Caviedes, Pablo.
    Abstract Background Mutations in the gene encoding for dysferlin cause recessive autosomal muscular dystrophies called dysferlinopathies. These mutations induce several alterations in skeletal muscles, including, inflammation, increased membrane permeability and cell death. Despite the fact that the etiology of dysferlinopathies is known, the mechanism that explains the aforementioned alterations is still elusive. Therefore, we have now evaluated the potential involvement of connexin based hemichannels in the pathophysiology of dysferlinopathies. Results Human deltoid muscle biopsies of 5 Chilean dysferlinopathy patients exhibited the presence of muscular connexins (Cx40.1, Cx43 and Cx45). The presence of these connexins was also observed in human myotubes derived from immortalized myoblasts derived from other patients with mutated forms of dysferlin. In addition to the aforementioned connexins, these myotubes expressed functional connexin based hemichannels, evaluated by ethidium uptake assays, as opposed to myotubes obtained from a normal human muscle cell line, RCMH. This response was reproduced in a knock-down model of dysferlin, by treating RCMH cell line with small hairpin RNA specific for dysferlin (RCMH-sh Dysferlin). Also, the presence of P2X7 receptor and the transient receptor potential channel, TRPV2, another Ca2+ permeable channels, was detected in the myotubes expressing mutated dysferlin, and an elevated resting intracellular Ca2+ level was found in the latter myotubes, which was in turn reduced to control levels in the presence of the molecule D4, a selective Cx HCs inhibitor. Conclusions The data suggests that dysferlin deficiency, caused by mutation or downregulation of dysferlin, promotes the expression of Cx HCs. Then, the de novo expression Cx HC causes a dysregulation of intracellular free Ca2+ levels, which could underlie muscular damage associated to dysferlin mutations. This mechanism could constitute a potential therapeutical target in dysferlinopathies.