1
|
Phosphodiesterase 5a Signalling in Skeletal Muscle Pathophysiology. Int J Mol Sci 2022; 24:ijms24010703. [PMID: 36614143 PMCID: PMC9820699 DOI: 10.3390/ijms24010703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/20/2022] [Accepted: 12/27/2022] [Indexed: 01/03/2023] Open
Abstract
Phosphodiesterase 5A (PDE5A) is involved in cGMP hydrolysis, regulating many physiological processes. Increased activity of PDE5A has been found in several pathological conditions, and the pharmacological inhibition of PDE5 has been demonstrated to have several therapeutic applications. We have identified the presence of three different Pde5a isoforms in cardiomyocytes, and we have found that the expression of specific Pde5a isoforms may have a causal role in the onset of pathological responses in these cells. In our previous study, we demonstrated that PDE5A inhibition could ameliorate muscular dystrophy by acting at different levels, as assessed by the altered genomic response of muscular cells following treatment with the PDE5A inhibitor tadalafil. Thus, considering the importance of PDE5A in various pathophysiological conditions, we further investigated the regulation of this enzyme. Here, we analysed the expression of Pde5a isoforms in the pathophysiology of skeletal muscle. We found that skeletal muscle tissues and myogenic cells express Pde5a1 and Pde5a2 isoforms, and we observed an increased expression of Pde5a1 in damaged skeletal muscles, while Pde5a2 levels remained unchanged. We also cloned and characterized the promoters that control the transcription of Pde5a isoforms, investigating which of the transcription factors predicted by bioinformatics analysis could be involved in their modulation. In conclusion, we found an overexpression of Pde5a1 in compromised muscle and identified an involvement of MyoD and Runx1 in Pde5a1 transcriptional activity.
Collapse
|
2
|
Lambert MR, Spinazzola JM, Widrick JJ, Pakula A, Conner JR, Chin JE, Owens JM, Kunkel LM. PDE10A Inhibition Reduces the Manifestation of Pathology in DMD Zebrafish and Represses the Genetic Modifier PITPNA. Mol Ther 2020; 29:1086-1101. [PMID: 33221436 PMCID: PMC7934586 DOI: 10.1016/j.ymthe.2020.11.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/04/2020] [Accepted: 11/15/2020] [Indexed: 12/25/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe genetic disorder caused by mutations in the DMD gene. Absence of dystrophin protein leads to progressive degradation of skeletal and cardiac function and leads to premature death. Over the years, zebrafish have been increasingly used for studying DMD and are a powerful tool for drug discovery and therapeutic development. In our study, a birefringence screening assay led to identification of phosphodiesterase 10A (PDE10A) inhibitors that reduced the manifestation of dystrophic muscle phenotype in dystrophin-deficient sapje-like zebrafish larvae. PDE10A has been validated as a therapeutic target by pde10a morpholino-mediated reduction in muscle pathology and improvement in locomotion, muscle, and vascular function as well as long-term survival in sapje-like larvae. PDE10A inhibition in zebrafish and DMD patient-derived myoblasts were also associated with reduction of PITPNA expression that has been previously identified as a protective genetic modifier in two exceptional dystrophin-deficient golden retriever muscular dystrophy (GRMD) dogs that escaped the dystrophic phenotype. The combination of a phenotypic assay and relevant functional assessments in the sapje-like zebrafish enhances the potential for the prospective discovery of DMD therapeutics. Indeed, our results suggest a new application for a PDE10A inhibitor as a potential DMD therapeutic to be investigated in a mouse model of DMD.
Collapse
Affiliation(s)
- Matthias R Lambert
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Janelle M Spinazzola
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Jeffrey J Widrick
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Anna Pakula
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - James R Conner
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Janice E Chin
- Rare Disease Research Unit, Pfizer, Cambridge, MA 02139, USA
| | - Jane M Owens
- Rare Disease Research Unit, Pfizer, Cambridge, MA 02139, USA
| | - Louis M Kunkel
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; The Stem Cell Program, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA; The Manton Center for Orphan Disease Research at Boston Children's Hospital, Boston, MA 02115, USA.
| |
Collapse
|
3
|
Podkalicka P, Mucha O, Dulak J, Loboda A. Targeting angiogenesis in Duchenne muscular dystrophy. Cell Mol Life Sci 2019; 76:1507-1528. [PMID: 30770952 PMCID: PMC6439152 DOI: 10.1007/s00018-019-03006-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 12/28/2018] [Accepted: 01/07/2019] [Indexed: 02/07/2023]
Abstract
Duchenne muscular dystrophy (DMD) represents one of the most devastating types of muscular dystrophies which affect boys already at early childhood. Despite the fact that the primary cause of the disease, namely the lack of functional dystrophin is known already for more than 30 years, DMD still remains an incurable disease. Thus, an enormous effort has been made during recent years to reveal novel mechanisms that could provide therapeutic targets for DMD, especially because glucocorticoids treatment acts mostly symptomatic and exerts many side effects, whereas the effectiveness of genetic approaches aiming at the restoration of functional dystrophin is under the constant debate. Taking into account that dystrophin expression is not restricted to muscle cells, but is present also in, e.g., endothelial cells, alterations in angiogenesis process have been proposed to have a significant impact on DMD progression. Indeed, already before the discovery of dystrophin, several abnormalities in blood vessels structure and function have been revealed, suggesting that targeting angiogenesis could be beneficial in DMD. In this review, we will summarize current knowledge about the angiogenesis status both in animal models of DMD as well as in DMD patients, focusing on different organs as well as age- and sex-dependent effects. Moreover, we will critically discuss some approaches such as modulation of vascular endothelial growth factor or nitric oxide related pathways, to enhance angiogenesis and attenuate the dystrophic phenotype. Additionally, we will suggest the potential role of other mediators, such as heme oxygenase-1 or statins in those processes.
Collapse
Affiliation(s)
- Paulina Podkalicka
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Olga Mucha
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Jozef Dulak
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Agnieszka Loboda
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
| |
Collapse
|
4
|
Balke JE, Zhang L, Percival JM. Neuronal nitric oxide synthase (nNOS) splice variant function: Insights into nitric oxide signaling from skeletal muscle. Nitric Oxide 2018; 82:35-47. [PMID: 30503614 DOI: 10.1016/j.niox.2018.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 11/19/2018] [Accepted: 11/20/2018] [Indexed: 02/07/2023]
Abstract
Defects in neuronal nitric oxide synthase (nNOS) splice variant localization and signaling in skeletal muscle are a firmly established pathogenic characteristic of many neuromuscular diseases, including Duchenne and Becker muscular dystrophy (DMD and BMD, respectively). Therefore, substantial efforts have been made to understand and therapeutically target skeletal muscle nNOS isoform signaling. The purpose of this review is to summarize recent salient advances in understanding of the regulation, targeting, and function of nNOSμ and nNOSβ splice variants in normal and dystrophic skeletal muscle, primarily using findings from mouse models. The first focus of this review is how the differential targeting of nNOS splice variants creates spatially and functionally distinct nitric oxide (NO) signaling compartments at the sarcolemma, Golgi complex, and cytoplasm. Particular attention is given to the functions of sarcolemmal nNOSμ and limitations of current nNOS knockout models. The second major focus is to review current understanding of cGMP-mediated nNOS signaling in skeletal muscle and its emergence as a therapeutic target in DMD and BMD. Accordingly, we address the preclinical and clinical successes and setbacks with the testing of phosphodiesterase 5 inhibitors to redress nNOS signaling defects in DMD and BMD. In summary, this review of nNOS function in normal and dystrophic muscle aims to advance understanding how the messenger NO is harnessed for cellular signaling from a skeletal muscle perspective.
Collapse
Affiliation(s)
- Jordan E Balke
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine Miami, Florida, 33101, USA
| | - Ling Zhang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine Miami, Florida, 33101, USA
| | - Justin M Percival
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine Miami, Florida, 33101, USA.
| |
Collapse
|
5
|
Dombernowsky NW, Ölmestig JNE, Witting N, Kruuse C. Role of neuronal nitric oxide synthase (nNOS) in Duchenne and Becker muscular dystrophies - Still a possible treatment modality? Neuromuscul Disord 2018; 28:914-926. [PMID: 30352768 DOI: 10.1016/j.nmd.2018.09.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/07/2018] [Accepted: 09/05/2018] [Indexed: 02/08/2023]
Abstract
Neuronal nitric oxide synthase (nNOS) is involved in nitric oxide (NO) production and suggested to play a crucial role in blood flow regulation of skeletal muscle. During activation of the muscle, NO helps attenuate the sympathetic vasoconstriction to accommodate increased metabolic demands, a phenomenon known as functional sympatholysis. In inherited myopathies such as the dystrophinopathies Duchenne and Becker muscle dystrophies (DMD and BMD), nNOS is lost from the sarcolemma. The loss of nNOS may cause functional ischemia contributing to skeletal and cardiac muscle cell injury. Effects of NO is augmented by inhibiting degradation of the second messenger cyclic guanosine monophosphate (cGMP) using sildenafil and tadalafil, both of which inhibit the enzyme phosphodiesterase 5 (PDE5). In animal models of DMD, PDE5-inhibitors prevent functional ischemia, reduce post-exercise skeletal muscle pathology and fatigue, show amelioration of cardiac muscle cell damage and increase cardiac performance. However, effect on clinical outcomes in DMD and BMD patients have been disappointing with minor effects on upper limb performance and none on ambulation. This review aims to summarize the current knowledge of nNOS function related to functional sympatholysis in skeletal muscle and studies on PDE5-inhibitor treatment in nNOS-deficient animal models and patients.
Collapse
Affiliation(s)
- Nanna W Dombernowsky
- Department of Neurology, Rigshospitalet Glostrup, University of Copenhagen, Denmark
| | - Joakim N E Ölmestig
- Department of Neurology, Neurovascular Research Unit, Herlev Gentofte Hospital, University of Copenhagen, Denmark
| | - Nanna Witting
- Department of Neurology, Rigshospitalet Glostrup, University of Copenhagen, Denmark
| | - Christina Kruuse
- Department of Neurology, Neurovascular Research Unit, Herlev Gentofte Hospital, University of Copenhagen, Denmark; PDE Research Group, Lundbeck Foundation Center for Neurovascular Research (LUCENS), Denmark.
| |
Collapse
|
6
|
Tetsi L, Charles AL, Paradis S, Lejay A, Talha S, Geny B, Lugnier C. Effects of cyclic nucleotide phosphodiesterases (PDEs) on mitochondrial skeletal muscle functions. Cell Mol Life Sci 2017; 74:1883-1893. [PMID: 28039524 PMCID: PMC11107545 DOI: 10.1007/s00018-016-2446-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 12/12/2016] [Accepted: 12/19/2016] [Indexed: 12/31/2022]
Abstract
Mitochondria play a critical role in skeletal muscle metabolism and function, notably at the level of tissue respiration, which conduct muscle strength as well as muscle survival. Pathological conditions induce mitochondria dysfunctions notably characterized by free oxygen radical production disturbing intracellular signaling. In that way, the second messengers, cyclic AMP and cyclic GMP, control intracellular signaling at the physiological and transcription levels by governing phosphorylation cascades. Both nucleotides are specifically and selectively hydrolyzed in their respective 5'-nucleotide by cyclic nucleotide phosphodiesterases (PDEs), which constitute a multi-genic family differently tissue distributed and subcellularly compartmentalized. These PDEs are presently recognized as therapeutic targets for cardiovascular, pulmonary, and neurologic diseases. However, very few data concerning cyclic nucleotides and PDEs in skeletal muscle, specifically in mitochondria, are reported in the literature. The knowledge of PDE implication in mitochondrial signaling would be helpful for resolving critical mitochondrial dysfunctions in skeletal muscle.
Collapse
Affiliation(s)
- Liliane Tetsi
- EA 3072 "Mitochondrie, Stress Oxydant et Protection Musculaire", Fédération de Médecine Translationnelle, Faculté de Médecine, Institut de Physiologie, Université de Strasbourg, 4, Rue Kirschleger, 67085, Strasbourg Cedex, France
| | - Anne-Laure Charles
- EA 3072 "Mitochondrie, Stress Oxydant et Protection Musculaire", Fédération de Médecine Translationnelle, Faculté de Médecine, Institut de Physiologie, Université de Strasbourg, 4, Rue Kirschleger, 67085, Strasbourg Cedex, France
| | - Stéphanie Paradis
- EA 3072 "Mitochondrie, Stress Oxydant et Protection Musculaire", Fédération de Médecine Translationnelle, Faculté de Médecine, Institut de Physiologie, Université de Strasbourg, 4, Rue Kirschleger, 67085, Strasbourg Cedex, France
| | - Anne Lejay
- EA 3072 "Mitochondrie, Stress Oxydant et Protection Musculaire", Fédération de Médecine Translationnelle, Faculté de Médecine, Institut de Physiologie, Université de Strasbourg, 4, Rue Kirschleger, 67085, Strasbourg Cedex, France
| | - Samy Talha
- EA 3072 "Mitochondrie, Stress Oxydant et Protection Musculaire", Fédération de Médecine Translationnelle, Faculté de Médecine, Institut de Physiologie, Université de Strasbourg, 4, Rue Kirschleger, 67085, Strasbourg Cedex, France
| | - Bernard Geny
- EA 3072 "Mitochondrie, Stress Oxydant et Protection Musculaire", Fédération de Médecine Translationnelle, Faculté de Médecine, Institut de Physiologie, Université de Strasbourg, 4, Rue Kirschleger, 67085, Strasbourg Cedex, France
| | - Claire Lugnier
- EA 3072 "Mitochondrie, Stress Oxydant et Protection Musculaire", Fédération de Médecine Translationnelle, Faculté de Médecine, Institut de Physiologie, Université de Strasbourg, 4, Rue Kirschleger, 67085, Strasbourg Cedex, France.
| |
Collapse
|
7
|
Ackermann MA, Ward CW, Gurnett C, Kontrogianni-Konstantopoulos A. Myosin Binding Protein-C Slow Phosphorylation is Altered in Duchenne Dystrophy and Arthrogryposis Myopathy in Fast-Twitch Skeletal Muscles. Sci Rep 2015; 5:13235. [PMID: 26287277 PMCID: PMC4642557 DOI: 10.1038/srep13235] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/05/2015] [Indexed: 11/09/2022] Open
Abstract
Myosin Binding Protein-C slow (sMyBP-C), encoded by MYBPC1, comprises a family of regulatory proteins of skeletal muscles that are phosphorylated by PKA and PKC. MYBPC1 missense mutations are linked to the development of Distal Arthrogryposis-1 (DA-1). Although structure-function details for this myopathy are evolving, function is undoubtedly driven by sequence variations and post-translational modifications in sMyBP-C. Herein, we examined the phosphorylation profile of sMyBP-C in mouse and human fast-twitch skeletal muscles. We used Flexor Digitorum Brevis (FDB) isolated from young (~2-months old) and old (~14-months old) wild type and mdx mice, and human Abductor Hallucis (AH) and gastrocnemious muscles carrying the DA-1 mutations. Our results indicate both constitutive and differential phosphorylation of sMyBP-C in aged and diseased muscles. We report a 7-35% reduction in the phosphorylation levels of select sites in old wild type and young or old mdx FDB mouse muscles, compared to young wild type tissue. Similarly, we observe a 30-70% decrease in the phosphorylation levels of all PKA and PKC phospho-sites in the DA-1 AH, but not gastrocnemius, muscle. Overall, our studies show that the phosphorylation pattern of sMyBP-C is differentially regulated in response to age and disease, suggesting that phosphorylation plays important roles in these processes.
Collapse
Affiliation(s)
- Maegen A Ackermann
- University of Maryland, School of Medicine, Department of Biochemistry and Molecular Biology, Baltimore, MD, USA
| | | | - Christina Gurnett
- Washington University, School of Medicine, Department of Neurology, St. Louis, MO, USA
| | | |
Collapse
|
8
|
Berdeaux R, Stewart R. cAMP signaling in skeletal muscle adaptation: hypertrophy, metabolism, and regeneration. Am J Physiol Endocrinol Metab 2012; 303:E1-17. [PMID: 22354781 PMCID: PMC3404564 DOI: 10.1152/ajpendo.00555.2011] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 02/09/2012] [Indexed: 12/11/2022]
Abstract
Among organ systems, skeletal muscle is perhaps the most structurally specialized. The remarkable subcellular architecture of this tissue allows it to empower movement with instructions from motor neurons. Despite this high degree of specialization, skeletal muscle also has intrinsic signaling mechanisms that allow adaptation to long-term changes in demand and regeneration after acute damage. The second messenger adenosine 3',5'-monophosphate (cAMP) not only elicits acute changes within myofibers during exercise but also contributes to myofiber size and metabolic phenotype in the long term. Strikingly, sustained activation of cAMP signaling leads to pronounced hypertrophic responses in skeletal myofibers through largely elusive molecular mechanisms. These pathways can promote hypertrophy and combat atrophy in animal models of disorders including muscular dystrophy, age-related atrophy, denervation injury, disuse atrophy, cancer cachexia, and sepsis. cAMP also participates in muscle development and regeneration mediated by muscle precursor cells; thus, downstream signaling pathways may potentially be harnessed to promote muscle regeneration in patients with acute damage or muscular dystrophy. In this review, we summarize studies implicating cAMP signaling in skeletal muscle adaptation. We also highlight ligands that induce cAMP signaling and downstream effectors that are promising pharmacological targets.
Collapse
Affiliation(s)
- Rebecca Berdeaux
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA.
| | | |
Collapse
|
9
|
Sarcolemma-localized nNOS is required to maintain activity after mild exercise. Nature 2008; 456:511-5. [PMID: 18953332 PMCID: PMC2588643 DOI: 10.1038/nature07414] [Citation(s) in RCA: 233] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 08/29/2008] [Indexed: 02/08/2023]
Abstract
Many neuromuscular conditions are characterized by an exaggerated exercise-induced fatigue response that is disproportionate to activity level. This fatigue does not necessarily correlate with elevated central or peripheral fatigue in patients1, and some patients experience severe fatigue without any demonstrable somatic disease2. Except in myopathies that are due to specific metabolic defects, the mechanism underlying this type of fatigue remains unknown2. With no treatment available, this form of inactivity is a major determinant of disability3. Here we show, using mouse models, that this exaggerated fatigue response is distinct from a loss in specific force production by muscle, and that sarcolemma-localized nNOS signaling in skeletal muscle is required to maintain activity after mild exercise. Of significance, we show that nNOS-null mice do not have muscle pathology and have no loss of muscle specific-force after exercise, but do display this exaggerated fatigue response to mild exercise. In mouse models of nNOS mislocalization from the sarcolemma, prolonged inactivity was only relieved by pharmacologically enhancing the cGMP signal that results from muscle nNOS activation during the nitric oxide signaling response to mild exercise. Our findings suggest that the mechanism underlying the exaggerated fatigue response to mild exercise is a lack of contraction-induced signaling from sarcolemma-localized nNOS, which reduces cGMP-mediated vasomodulation in the vessels that supply active muscle after mild exercise. Notably, sarcolemmal nNOS was reduced in patient biopsies from a large number of distinct myopathies, suggesting a common mechanism of fatigue. Our results suggest that patients with an exaggerated fatigue response to mild exercise would show clinical improvement in response to treatment strategies aimed at improving exercise-induced signaling.
Collapse
|
10
|
Lynch GS, Ryall JG. Role of beta-adrenoceptor signaling in skeletal muscle: implications for muscle wasting and disease. Physiol Rev 2008; 88:729-67. [PMID: 18391178 DOI: 10.1152/physrev.00028.2007] [Citation(s) in RCA: 295] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The importance of beta-adrenergic signaling in the heart has been well documented, but it is only more recently that we have begun to understand the importance of this signaling pathway in skeletal muscle. There is considerable evidence regarding the stimulation of the beta-adrenergic system with beta-adrenoceptor agonists (beta-agonists). Although traditionally used for treating bronchospasm, it became apparent that some beta-agonists could increase skeletal muscle mass and decrease body fat. These so-called "repartitioning effects" proved desirable for the livestock industry trying to improve feed efficiency and meat quality. Studying beta-agonist effects on skeletal muscle has identified potential therapeutic applications for muscle wasting conditions such as sarcopenia, cancer cachexia, denervation, and neuromuscular diseases, aiming to attenuate (or potentially reverse) the muscle wasting and associated muscle weakness, and to enhance muscle growth and repair after injury. Some undesirable cardiovascular side effects of beta-agonists have so far limited their therapeutic potential. This review describes the physiological significance of beta-adrenergic signaling in skeletal muscle and examines the effects of beta-agonists on skeletal muscle structure and function. In addition, we examine the proposed beneficial effects of beta-agonist administration on skeletal muscle along with some of the less desirable cardiovascular effects. Understanding beta-adrenergic signaling in skeletal muscle is important for identifying new therapeutic targets and identifying novel approaches to attenuate the muscle wasting concomitant with many diseases.
Collapse
Affiliation(s)
- Gordon S Lynch
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia.
| | | |
Collapse
|