MUSCLE DAMAGEMUSCLE DAMAGE
4 CHAPTER -GENERAL CONCLUSIONS AND PERSPECTIVES
As Duchenne Muscular Dystrophy is one of the most severe and frequent muscular disease, intensive work has been done to understand processes implicated in muscle degradation. Even though no treatment is available yet, the cause of the myopathy is fully known. The absence of the plasma membrane protein dystrophin leads to greater membrane fragility toward mechanical stress that triggers muscle degradation. It has been proposed that cytosolic Ca2+ could be involved in the muscle loss, as the ion is indirectly responsible for the activation of numerous “death” proteins such as caspases. This hypothesis based on Ca2+
toxicity in DMD is still debated.
The present work was defined to improve our understanding of Ca2+ homeostasis in myotubes derived from dystrophic mice, and to submit possibilities or clues for effective treatment for the disease. Using the Ca2+-sensitive photoprotein aequorin, which can be targeted in almost all subcellular compartments, we were able to study the effect of the physiological activation of the nAChR on the subsarcolemmal and mitochondrial Ca2+
responses. We investigated the role of an important Ca2+ release channel located on the sarcoplasmic reticulum membrane, IP3R. Earlier experiments showed that the IP3R and its messenger IP3 are increased in dystrophic myotubes derived from both human and mice (Liberona et al., 1998). Surprisingly, no more work concerning the receptor has been done in DMD although the IP3R pathway could represent a potential target for drug treatment. As a potential effector of Ca2+ deregulation, the IP3R study was very challenging.
Moreover, as numerous data concerning Ca2+ overload in the disease have been accumulated in our laboratory, we have overexpressed the anti-apoptotic protein Bcl-2 in our dystrophic myotubes. Indeed, this protein has been shown the modulate Ca2+ homeostasis once it has been overexpressed in the cell. Thus, our working hypothesis was that Bcl-2 could prevent muscle degradation in dystrophic myotubes by its effect on Ca2+ homeostasis.
Here, we have shown that dystrophic myotubes display exaggerated mitochondrial and subsarcolemmal Ca2+ transients when Ca2+ responses are triggered by activation of the nAChR with CCh. We also show that IP3R is involved in Ca2+ release from the store in dystrophic myotubes only. Potent IP3 inhibitors greatly reduced the CCh-induced Ca2+
responses in these cells while Ca2+ responses in control C57 myotubes remained unaffected
by these inhibitors. We demonstrate that Bcl-2 prevents staurosporine-induced apoptosis in dystrophic myotubes only, presumably by a direct inhibition of the IP3R. We provide evidence of the involvement of IP3R in the Ca2+ leak and apoptosis triggered by staurosporine. Indeed, IP3R inhibitors decrease staurosporine-induced apoptosis which shows that IP3R are implicated in increased apoptosis observed in mdx myotubes.
Briefly, our conclusions are that in dystrophic myotubes, the IP3 pathway triggers exaggerated nAChR-induced Ca2+ responses. Refilling capability of the cell could handle this overload for a certain amount of time. After that, the cell may not able to pump back Ca2+
into the stores (SERCA) and the elevated cytosolic Ca2+ may push it towards apoptosis. Bcl-2, by decreasing the Ca2+ release function of the IP3R could prevent Ca2+ overload and the subsequent muscle degradation that occurs in DMD (see figure 4.1 for a recapitulative scheme). It would be interesting to clearly characterize the interaction(s) between both proteins in our cellular model. Although it is known that Bcl-2 directly interacts with IP3R in other cell types (Chen et al., 2004), the exact mechanism of inhibition remains to be determined. Moreover, it would be of interest to study the phosphorylation state of the IP3R in Bcl-2 overexpressing myotubes. Indeed, the activity of the receptor is closely linked to its phosphorylation degree (Krizanova & Ondrias, 2003). Bcl-2 could also act by modifying these properties.
The potential key role of the IP3R might lead to new treatments for DMD. The vast amount of knowledge on the receptor could indeed allow the design of specific drugs.
However, due to the wide expression of this receptor in all cell types, precautions will have to be taken in order to avoid side effects, principally in the central nervous system.
The overexpression of Bcl-2 in our myotubes decreased the staurosporine-induced apoptosis and the amplitude of the carbachol-induced Ca2+ responses in the subsarcolemmal area and in mitochondria. The overexpression of such anti-apoptotic protein could be criticized as toxicity of transient Bcl-2 overexpression has been reported (Uhlmann et al., 1998) and as Bcl-2 overexpression could trigger alteration in the expression of proteins involved in Ca2+ homeostasis (Distelhorst & Shore, 2004). However, no visual and physiological modifications were observed in our transfected myotubes. As Bcl-2 was not detected in non-transfected cells, the only way to study its effect was overexpression. Thus, it would be of interest to find a way to increase the endogenous expression of this anti-apoptotic protein.
Figure 4.1: Summary scheme of CCh-induced Ca2+ responses in skeletal myotubes.
(A) Control C57 myotubes, (B) dystrophic myotubes. Plain arrows represent known pathways. Hatched arrows mean hypothetical pathway.
1- The activation of the nAChR with CCh triggers Na+ entry through the receptor. 2- Na+ entry depolarizes the plasma membrane and activates VOCs (DHPR). 3- Ca2+ influx occurs through these voltage-gated channels. 4- In control C57 myotubes, this influx activates RyRs that release Ca2+ from the SR while in dystrophic myotubes PLC is activated by Ca2+ increases, membrane depolarization or G protein. Activation of PLC leads to IP3 formation which activates IP3R. IP3Rs release Ca2+ from the store. Bcl-2 could inhibit this receptor and the subsequent Ca2+ release. 5- Ca2+ release from the store increases pm[Ca2+] that can be pumped back by SERCA for store refilling. 6- In case of long term Ca2+ elevation, apoptosis is triggered by mitochondria. Bcl-2 inhibits apoptosis.
Finally, the use of anti-apoptotic proteins as a potential treatment for DMD should be considered carefully as the possible cell immortalization brought by the protein could result in tumor formation. This transient overexpression has shown that it is possible to enhance survival of skeletal muscle cell derived from dystrophic mice by decreasing Ca2+
concentration. Further work should take into account this possibility, together with the implication of the IP3R.
The use of myotubes obtained from purified satellite cell lines allows performing numerous experiments under controlled conditions. However, myotubes are non mature cells and are quite far in term of physiology and genetic properties from mature fibers. Indeed, hundreds of proteins are expressed in their fetal form in myotubes, while they have adult form in fibers. Although the use of fibers should represent another model for studying skeletal muscle biology, the difficulties to obtain intact fibers in a sufficient number after muscle extraction limits the use of these cells. Moreover, in our particular case, the use of fibers is limited as these cells are difficult to transfect so that the aequorin technique could not be optimal. Altogether, these remarks indicate that even if the use of fibers is another solution to fit better with “reality”, myotubes are more attractive for basic experiments such as intracellular Ca2+ measurement, immunochemistry or western blots. Nevertheless, IP3R study in dystrophic fibers would be interesting.
In conclusion, even if the etiology of DMD appears relatively simple because it is a monogenic disease, the mechanisms linking of the lack of dystrophin to disease remain unclear. More work need to be done in order to clarify all the consequences of the absence of the protein, and to find an effective treatment. This work brought to the light the possible key role of the IP3R and its possible regulation by Bcl-2 of the mdx dystrophy. Even if genetic research has opened new doors with the era of DNA delivery, and if most of the hope for a cure is concentrated on this approach, basic research is still central for a better understanding of the disease. Pharmacology is still promising for DMD patients, for the improvement of the way of life and for a better treatment.
5 REFERENCES
AARTSMA-RUS, A., JANSON, A., KAMAN, W., BREMMER-BOUT, M., VAN OMMEN, G., DEN
DUNNEN,J. & VAN DEUTEKOM,J. (2004). Antisense-induced multiexon skipping for Duchenne muscular dystrophy makes more sense. Am J Hum Genet 74, 83-92.
ADACHI-AKAHANE,S., CLEEMANN,L. & MORAD,M. (1996). Cross-signaling between L-type Ca2+ channels and ryanodine receptors in rat ventricular myocytes. J. Gen. Physiol.
108, 435-454.
AFM. (2001). Duchenne muscular Dystrophy: Description, Treatment and Research. Annual Review.
AKKARAJU,G., HUARD,J., HOFFMAN,E., GOINS,W., PRUCHNIC,R., WATKINS,S., COHEN,J.
& GLORIOSO, J. (1999). Herpes simplex virus vector-mediated dystrophin gene transfer and expression in MDX mouse skeletal muscle. J Gene Med 1, 280-289.
ALDERTON, J. M. & STEINHARDT, R. A. (2000). Calcium influx through calcium leak channels is responsible for the elevated levels of calcium-dependent proteolysis in dystrophic myotubes. J. Biol. Chem. 275, 9452-9460.
ALIKHANI,M., ALIKHANI,Z., RAPTIS,M. & GRAVES,D. (2004). TNF-alpha in vivo stimulates apoptosis in fibroblasts through caspase-8 activation and modulates the expression of pro-apoptotic genes. J Cell Physiol 201, 341-348.
ALLAMAND,V. & CAMPBELL,K.P. (2000). Animal models for muscular dystrophy: valuable tools for the development of therapies. Hum. Mol. Genet. 9, 2459-2467.
ALVAREZ, J. & MONTERO, M. (2002). Measuring [Ca2+] in the endoplasmic reticulum with aequorin. Cell Calcium 32, 251-260.
ANTONSSON, B. & MARTINOU, J.-C. (2000). The Bcl-2 Protein Family. Experimental Cell Research 256, 50-57.
ANTONSSON, B., MONTESSUIT, S., LAUPER, S., ESKES, R. & MARTINOU, J. (2000). Bax oligomerization is required for channel-forming activity in liposomes and to trigger cytochrome c release from mitochondria. Biochem J 345, 271-278.
ARAKAWA, M., SHIOZUKA, M., NAKAYAMA, Y., HARA, T., HAMADA, M., KONDO, S. I., IKEDA, D., TAKAHASHI, Y., SAWA, R., NONOMURA, Y., SHEYKHOLESLAMI, K., KONDO, K., KAGA, K., KITAMURA, T., SUZUKI-MIYAGOE, Y., TAKEDA, S. I. &
MATSUDA, R. (2003). Negamycin Restores Dystrophin Expression in Skeletal and Cardiac Muscles of mdx Mice. J Biochem (Tokyo) 134, 751-758.
ARAYA, R., LIBERONA, J.L., CARDENAS, J.C., RIVEROS, N., ESTRADA, M., POWELL, J.A., CARRASCO, M. A. & JAIMOVICH, E. (2002). Dihydropyridine Receptors as Voltage Sensors for a Depolarization-evoked, IP3R-mediated, Slow Calcium Signal in Skeletal Muscle Cells. J. Gen. Physiol. 121, 3-16.
ASSEFA, Z., BULTYNCK, G., SZLUFCIK, K., NADIF KASRI, N., VERMASSEN, E., GORIS, J., MISSIAEN, L., CALLEWAERT, G., PARYS, J. B. & DE SMEDT, H. (2004). Caspase-3-induced Truncation of Type 1 Inositol Trisphosphate Receptor Accelerates Apoptotic Cell Death and Induces Inositol Trisphosphate-independent Calcium Release during Apoptosis. J. Biol. Chem. 279, 43227-43236.
BADALAMENTE,M.A. & STRACHER,A. (2000). Delay of muscle degeneration and necrosis in mdx mice by calpain inhibition. Muscle Nerve 23, 106-111.
BARTON-DAVIS, E. R., CORDIER, L., SHOTURMA, D. I., LELAND, S. E. & SWEENEY, H. L.
(1999). Aminoglycoside antibiotics restore dystrophin function to skeletal muscles of mdx mice. J. Clin. Invest. 104, 375-381.
BELZACQ, A.-S., VIEIRA, H. L. A., VERRIER, F., VANDECASTEELE, G., COHEN, I., PREVOST, M.-C., LARQUET,E., PARISELLI,F., PETIT,P.X., KAHN,A., RIZZUTO,R., BRENNER,C.
& KROEMER, G. (2003). Bcl-2 and Bax Modulate Adenine Nucleotide Translocase Activity. Cancer. Res. 63, 541-546.
BENKUSKY, N. A., FARRELL, E. F. & VALDIVIA, H. H. (2004). Ryanodine receptor channelopathies. Biochem. Biophys. Res. Com. 322, 1280-1285.
BENNETT, D.L., PETERSEN, C.C.H. & CHEEK, T.R. (1995). Calcium Signalling - Cracking I(CRAC) in the eye. Curr. Biol. 5, 1225-1228.
BERCHTOLD, M. W., BRINKMEIER, H. & MUNTENER, M. (2000). Calcium ion in skeletal muscle: Its crucial role for muscle function, plasticity, and disease. Physiol. Rev. 80, 1215-1265.
BERMUDEZ DE LEON, M., MONTANEZ, C., GOMEZ, P., MORALES-LAZARO, S. L., TAPIA -RAMIREZ,V., VALADEZ-GRAHAM,V., RECILLAS-TARGA,F., YAFFE,D., NUDEL,U. &
CISNEROS, B. (2004). Dystrophin Dp71 gene expression is down-regulated during myogenesis: Role of Sp1 and Sp3 on the Dp71 promoter activity. J. Biol. Chem., M411571200.
BERNARDI, P. (1999). Mitochondrial transport of cations: channels, exchangers, and permeability transition. Physiol. Rev. 79, 1127-1155.
BERRIDGE, M. (2004). Conformational Coupling: A Physiological Calcium Entry Mechanism. Science's stke 2004, pe33-.
BERRIDGE,M.J., BOOTMAN,M.D. & RODERICK,H.L. (2003). Calcium signalling: dynamics, homeostasis and remodelling. Nat Rev Mol Cell Biol 4, 517-529.
BERTORINI, T., PALMIERI, G., GRIFFIN, J., IGARASHI, M., HINTON, A. & KARAS, J. (1991).
Effect of dantrolene in Duchenne muscular dystrophy. Muscle Nerve 14, 503-507.
BEZPROZVANNY, I. & EHRLICH,B. E. (1993). ATP modulates the function of inositol 1,4,5-trisphosphate-gated channels at two sites. Neuron 10, 1175-1184.
BEZPROZVANNY, I., WATRAS, J. & EHRLICH, B. E. (1991). Bell-shaped calcium-response curves of Ins(1, 4, 5)P3- and calcium- gated channels from endoplasmic reticulum of cerebellum. Nature 351, 751-754.
BIGGAR, W. D., GINGRAS, M., FEHLINGS, D. L., HARRIS, V. A. & STEELE, C. A. (2001).
Deflazacort treatment of Duchenne muscular dystrophy. The Journal of Pediatrics 138, 45-50.
BOEHNING,D., PATTERSON,R., SEDAGHAT,L., GLEBOVA,N., KUROSAKI,T. & SNYDER,S.H.
(2003). Cytochrome c binds to inositol (1, 4, 5) trisphosphate receptors, amplifying calcium-dependent apoptosis. Nat Cell Biol 5, 1051-1061.
BOGDANOVICH,S., KRAG,T.O., BARTON,E.R., MORRIS,L.D., WHITTEMORE,L.A., AHIMA, R. S. & KHURANA, T. S. (2002). Functional improvement of dystrophic muscle by myostatin blockade. Nature 420, 418-421.
BOITTIN, F.-X., MACREZ, N., HALET, G. & MIRONNEAU, J. (1999). Norepinephrine-induced Ca2+ waves depend on InsP3 and ryanodine receptor activation in vascular myocytes.
Am J Physiol Cell Physiol 277, C139-151.
BONIFATI,M., RUZZA,G., BONOMETTO,P., BERARDINELLI,A., GORNI,K., ORCESI,S., LANZI, G. & ANGELINI, C. (2000). A multicenter, double-blind, randomized trial of deflazacort versus prednisone in Duchenne muscular dystrophy. Muscle Nerve 23, 1344-1347.
BONILLA, E., SAMITT, C. E., MIRANDA, A. F., HAYS, A. P., SALVIATI, G., DIMAURO, S., KUNKEL, L. M., HOFFMAN, E. P. & ROWLAND, L. P. (1988). Duchenne muscular dystrophy: deficiency of dystrophin at the muscle cell surface. Cell 54, 447-452.
BOURGUIGNON,L. Y. & JIN,H. (1995). Identification of the ankyrin-binding domain of the mouse T- lymphoma cell inositol 1, 4, 5-trisphosphate (IP3) receptor and its role in the regulation of IP3-mediated internal Ca2+ release. J. Biol. Chem. 270, 7257-7260.
BRECKENRIDGE,D., GERMAIN,M., MATHAI,J., NGUYEN,M. & SHORE,G. (2003). Regulation of apoptosis by endoplasmic reticulum pathways. Oncogene 22, 8608-8618.
BRENMAN, J., CHAO, D., XIA, H., ALDAPE, K. & BREDT, D. (1995). Nitric oxide synthase complexed with dystrophin and absent from skeletal muscle sarcolemma in Duchenne muscular dystrophy. Cell 82, 743-752.
BRINI,M. (2004). Ryanodine receptor defects in muscle genetic diseases. Biochem. Biophys.
Res. Com. 322, 1245-1255.
BRINI,M., BANO,D., MANNI,S., RIZZUTO,R. & CARAFOLI,E. (2000). Effects of PMCA and SERCA pump overexpression on the kinetics of cell Ca2+ signalling. EMBO J. 19, 4926-4935.
BRINI, M., PINTON, P., POZZAN,T. & RIZZUTO,R. (1999). Targeted recombinant aequorins:
tools for monitoring [Ca2+] in the various compartments of a living cell. Microsc. Res.
Tech. 46, 380-389.
BROWN,T.L., PATIL,S., CIANCI,C.D., MORROW,J.S. & HOWE,P.H. (1999). Transforming Growth Factor beta Induces Caspase 3-independent Cleavage of alpha II-Spectrin (alpha -Fodrin) Coincident with Apoptosis. J. Biol. Chem. 274, 23256-23262.
CAIN,K., BRATTON,S.B. & COHEN,G.M. (2002). The Apaf-1 apoptosome: a large caspase-activating complex. Biochimie 84, 203-214.
CARAFOLI, E. (2003). Historical review: Mitochondria and calcium: ups and downs of an unusual relationship. Trends in Biochemical Sciences 28, 175-181.
CHEN, R., VALENCIA, I., ZHONG, F., MCCOLL, K. S., RODERICK, H. L., BOOTMAN, M. D., BERRIDGE, M. J., CONWAY, S. J., HOLMES, A. B., MIGNERY, G. A., VELEZ, P. &
DISTELHORST, C. W. (2004). Bcl-2 functionally interacts with inositol 1, 4, 5-trisphosphate receptors to regulate calcium release from the ER in response to inositol 1, 4, 5-trisphosphate. J. Cell Biol. 166, 193-203.
CHITTENDEN, T., FLEMINGTON, C., HOUGHTON, A., EBB, R., GALLO, G., ELANGOVAN, B., CHINNADURAI,G. & LUTZ,R. (1995). A conserved domain in Bak, distinct from BH1 and BH2, mediates cell death and protein binding functions. EMBO J. 14, 5589-5596.
CLAPHAM,D.E. (2003). TRP channels as cellular sensors. Nature 426.
CLEARY, M., SMITH, S. & SKLAR, J. (1986). Cloning and structural analysis of cDNAs for Bcl-2 and a hybrid Bcl-2/immunoglobulin transcript resulting from the t(14;18) translocation. Cell 47, 19-28.
CONSTANTIN, B. & CRONIER, L. (2000). Involvement of gap junctional communication in myogenesis. Int. Rev. Cytol. 196, 1-65.
CROMPTON, M. (1999). The mitochondrial permeability transition pore and its role in cell death. Biochem. J. 341, 233-249.
CULLIGAN, K., BANVILLE, N., DOWLING,P. & OHLENDIECK,K. (2002). Drastic reduction of calsequestrin-like proteins and impaired calcium binding in dystrophic mdx muscle.
Journal of Applied Physiology 92, 435-445.
DE GIORGI,F., BRINI,M., BASTIANUTTO,C., MARSAULT,R., MONTERO,M., PIZZO,P., ROSSI, R. & RIZZUTO, R. (1996). Targeting aequorin and green fluorescent protein to intracellular organelles. Gene 173, 113-117.
DE LUCA, A., PIERNO, S., LIANTONIO, A., CETRONE, M., CAMERINO, C., FRAYSSE, B., MIRABELLA, M., SERVIDEI, S., RUEGG, U. T. & CONTE CAMERINO, D. (2003).
Enhanced dystrophic progression in mdx mice by exercise and beneficial effects of taurine and insulin-like growth factor-1. J. Pharmacol. Exp. Ther. 304, 453-463.
DEGTEREV,A., BOYCE, M. & YUAN,J. (2001). The channel of death. J. Cell Biol. 155, 695-698.
DELLORUSSO, C., SCOTT, J. M., HARTIGAN-O'CONNOR, D., SALVATORI, G., BARJOT, C., ROBINSON, A. S., CRAWFORD, R. W., BROOKS, S. V. & CHAMBERLAIN, J.S. (2002).
Functional correction of adult mdx mouse muscle using gutted adenoviral vectors expressing full-length dystrophin. Proc. Natl. Acad. Sci. USA 99, 12979-12984.
DEMAUREX,N. & DISTELHORST,C. (2003). Apoptosis--the Calcium connection. Science 300, 65-67.
DESAGHER, S., OSEN-SAND, A., NICHOLS, A., ESKES, R., MONTESSUIT, S., LAUPER, S., MAUNDRELL, K., ANTONSSON, B. & MARTINOU, J. C. (1999). Bid-induced conformational change of Bax is responsible for mitochondrial cytochrome c release during apoptosis. Journal of Cell Biology 144, 891-901.
DISTELHORST, C. & RODERICK, H. L. (2003). Ins(1,4,5)P3-mediated calcium signals and apoptosis: is there a role for Bcl-2? Biochemical Society Transactions 31, 958-959.
DISTELHORST,C. & SHORE,G.C. (2004). Bcl-2 and calcium: controversy beneath the surface.
Oncogene 23, 2875-2880.
DREMINA, E.S., SHAROV,V. S., KUMAR, K., ZAIDI,A., MICHAELIS, E.K. & SCHONEICH,C.
(2004). Antiapoptotic protein Bcl-2 interacts with and destabilizes the sarco/endoplasmic reticulum Ca-ATPase (SERCA). Biochem J.
DUNN,J.F. & RADDA,G.K. (1991). Total ion content of skeletal and cardiac muscle in the mdx mouse dystrophy: Ca2+ is elevated at all ages. J. Neurol. Sci. 103, 226-231.
EMERY,A.E.H. (2002). The muscular dystrophies. Lancet 359, 687-695.
ESKES, R., DESAGHER, S., ANTONSSON, B. & MARTINOU, J.-C. (2000). Bid Induces the Oligomerization and Insertion of Bax into the Outer Mitochondrial Membrane. Mol.
Cell. Biol. 20, 929-935.
FABB, S., WELLS, D., SERPENTE, P. & DICKSON, G. (2002). Adeno-associated virus vector gene transfer and sarcolemmal expression of a 144 kDa micro-dystrophin effectively restores the dystrophin-associated protein complex and inhibits myofibre degeneration in nude/mdx mice. Hum. Mol. Genet. 11, 733-741.
FEENER, C., KOENIG, M. & KUNKEL, L. (1989). Alternative splicing of human dystrophin mRNA generates isoforms at the carboxy terminus. Nature 338, 509-511.
FENICHEL,G.M., FLORENCE,J.M., PESTRONK,A., MENDELL,J.R., MOXLEY,R.T., GRIGGS, R. C., BROOKE, M. H., MILLER, J. P., ROBISON, J. & KING, W. (1994). Long-term benefit from prednisone therapy in Duchenne muscular dystrophy. Neurology 41, 1874-1877.
FERRIS, C. D., CAMERON, A. M., BREDT, D. S., HUGANIR, R. L. & SNYDER, S. H. (1992).
Autophosphorylation of inositol 1, 4, 5-trisphosphate receptors. J. Biol. Chem. 267, 7036-7041.
FERRIS, C. D., HUGANIR, R. L., BREDT, D. S., CAMERON, A. M. & SNYDER, S. H. (1991).
Inositol trisphosphate receptor: phosphorylation by protein kinase C and calcium calmodulin-dependent protein kinases in reconstituted lipid vesicles. Proc. Natl.
Acad. Sci. U.S.A. 88, 2232-2235.
FISHER,R., TINSLEY, J.M., PHELPS,S.R., SQUIRE,S.E., TOWNSEND,E.R., MARTIN,J.E. &
DAVIES, K. E. (2001). Non-toxic ubiquitous over-expression of utrophin in the mdx mouse. Neuromusc. Dis. (Abstract) 11, 713-721.
FOYOUZI-YOUSSEFI, R., ARNAUDEAU,S., BORNER,C., KELLEY, W.L., TSCHOPP,J., LEW, D.
P., DEMAUREX, N. & KRAUSE, K. H. (2000). Bcl-2 decreases the free Ca2+
concentration within the endoplasmic reticulum. Proc. Natl. Acad. Sci. USA 97, 5723-5728.
FRANCO-OBREGON, A. & LANSMAN, J. B. (2002). Changes in mechanosensitive channel gating following mechanical stimulation in skeletal muscle myotubes from the mdx mouse. J Physiol 539, 391-407.
FRANZINI-ARMSTRONG,C., KENNEY,L. & VARRIANO-MARSTON,E. (1987). The structure of calsequestrin in triads of vertebrate skeletal muscle: a deep-etch study. J. Cell Biol.
105, 49-56.
FRANZINI-ARMSTRONG,C. & PROTASI,F. (1997). Ryanodine receptors of striated muscles: a complex channel capable of multiple interactions. Physiol. Rev. 77, 699-729.
GAILLY,P., HERMANS,E., OCTAVE,J.N. & GILLIS,J.M. (1993). Specific increase of genetic expression of parvalbumin in fast skeletal muscles of mdx mice. FEBS Lett. 326, 272-274.
GAMEN,S., ANEL,A., PINEIRO,A. & NAVAL,J. (1998). Caspases are the main executioners of Fas-mediated apoptosis, irrespective of the ceramide signalling pathway. Cell Death Differ 5, 241-249.
GARCIA-SAEZ, A., MINGARRO, I., PEREZ-PAYA, E. & SALGADO, J. (2004). Membrane-insertion fragments of Bcl-xL, Bax, and Bid. Biochemistry 43, 10930-10943.
GILLIS, J.M. (1996). Membrane abnormalities and Ca homeostasis in muscles of the mdx mouse, an animal model of the Duchenne muscular dystrophy: a review. Acta Physiol.
Scand. 156, 397-406.
GOLLINS,H., MCMAHON,J., WELLS,K. & WELLS, D. (2003). High-efficiency plasmid gene transfer into dystrophic muscle. Gene Ther 10, 506-512.
GOROSPE,J.R., THARP,M.D., HINCKLEY,J., KORNEGAY,J.N. & HOFFMAN,E.P. (1994). A role for mast cells in the progression of Duchenne muscular dystrophy? Correlations in dystrophin-deficient humans, dogs, and mice. J. Neurol. Sci. 122, 44-56.
GRAMOLINI,A.O., ANGUS,L.M., SCHAEFFER,L., BURTON,E.A., TINSLEY,J.M., DAVIES,K.
E., CHANGEUX,J.P. & JASMIN,B.J. (1999). Induction of utrophin gene expression by
heregulin in skeletal muscle cells: role of the N-box motif and GA binding protein.
Proc. Natl. Acad. Sci. U.S.A. 96, 3223-3227.
GREEN,D.R. & REED,J.C. (1998). Mitochondria and apoptosis. Science 281, 1309-1312.
GROSS, A., JOCKEL, J., WEI, M. C. & KORSMEYER, S. J. (1998). Enforced dimerization of BAX results in its translocation, mitochondrial dysfunction and apoptosis. Embo J.
17, 3878-3885.
GROUNDS, M. & TORRISI, J. (2004). Anti-TNF{alpha} (Remicade®) therapy protects dystrophic skeletal muscle from necrosis. FASEB J. 18, 676-682.
GUNTER, T. E., BUNTINAS, L., SPARAGNA, G., ELISEEV, R. & GUNTER, K. (2000).
Mitochondrial calcium transport: mechanisms and functions. Cell Calcium 28, 285-296.
GUSSONI,E., BENNETT,R.R., MUSKIEWICZ,K.R., MEYERROSE,T., NOLTA,J.A., GILGOFF,I., STEIN, J., CHAN,Y.-M., LIDOV,H.G., BONNEMANN,C. G., VON MOERS, A., MORRIS, G. E., DEN DUNNEN, J. T., CHAMBERLAIN, J. S., KUNKEL, L. M. & WEINBERG, K.
(2002). Long-term persistence of donor nuclei in a Duchenne muscular dystrophy patient receiving bone marrow transplantation. J. Clin. Invest. 110, 807-814.
HAJNOCZKY, G., DAVIES, E. & MADESH, M. (2003). Calcium signaling and apoptosis.
Biochem. Biophys. Res. Com. 304, 445-454.
HAJNOCZKY, G., GAO, E., NOMURA, T., HOEK, J. B. & THOMAS, A. P. (1993). Multiple mechanisms by which protein kinase A potentiates inositol 1, 4, 5-trisphosphate-induced Ca2+ mobilization in permeabilized hepatocytes. Biochem. J. 293, 413-422.
HALESTRAP, A. P., MCSTAY, G. P., CLARKE, S. J. (2002). The permeability transition pore complex: another view. Biochimie 84, 153-166.
HENGARTNER,M.O. (2000). The biochemistry of apoptosis. Nature 407, 770-776.
HIDALGO,C., JORQUERA, J., TAPIA,V. & DONOSO, P. (1993). Triads and transverse tubules isolated from skeletal muscle contain high levels of inositol 1, 4, 5-trisphosphate. J.
Biol. Chem. 268, 15111-15117.
HODGETTS, S., SPENCER, M. & GROUNDS, M. (2003). A role for natural killer cells in the rapid death of cultured donor myoblasts after transplantation. Transplantation 75,
HODGETTS, S., SPENCER, M. & GROUNDS, M. (2003). A role for natural killer cells in the rapid death of cultured donor myoblasts after transplantation. Transplantation 75,