Decrease of myofiber branching via muscle-specific expression of the olfactory receptor mOR23 in dystrophic muscle leads to protection against mechanical stress
© Pichavant et al. 2016
Received: 19 October 2015
Accepted: 5 January 2016
Published: 21 January 2016
Abnormal branched myofibers within skeletal muscles are commonly found in diverse animal models of muscular dystrophy as well as in patients. Branched myofibers from dystrophic mice are more susceptible to break than unbranched myofibers suggesting that muscles containing a high percentage of these myofibers are more prone to injury. Previous studies showed ubiquitous over-expression of mouse olfactory receptor 23 (mOR23), a G protein-coupled receptor, in wild type mice decreased myofiber branching. Whether mOR23 over-expression specifically in skeletal muscle cells is sufficient to mitigate myofiber branching in dystrophic muscle is unknown.
We created a novel transgenic mouse over-expressing mOR23 specifically in muscle cells and then bred with dystrophic (mdx) mice. Myofiber branching was analyzed in these two transgenic mice and membrane integrity was assessed by Evans blue dye fluorescence.
mOR23 over-expression in muscle led to a decrease of myofiber branching after muscle regeneration in non-dystrophic mouse muscles and reduced the severity of myofiber branching in mdx mouse muscles. Muscles from mdx mouse over-expressing mOR23 significantly exhibited less damage to eccentric contractions than control mdx muscles.
The decrease of myofiber branching in mdx mouse muscles over-expressing mOR23 reduced the amount of membrane damage induced by mechanical stress. These results suggest that modifying myofiber branching in dystrophic patients, while not preventing degeneration, could be beneficial for mitigating some of the effects of the disease process.
KeywordsmOR23 Myofiber branching Mechanical stress Muscular dystrophy Muscle regeneration
Duchenne muscular dystrophy (DMD) is an X-linked disease due to the absence of dystrophin in muscle  that affects about one in every 3500 boys . The lack of dystrophin in DMD patients leads to progressive muscle degeneration and weakness resulting in death from heart or respiratory failure during the third decade of life. There is currently no curative treatment for this disease. One characteristic of dystrophic muscle is the presence of myofibers with an abnormal branching cytoarchitecture [3, 4]. These aberrant myofibers called branched myofibers or split myofibers contain one or more offshoots of daughter myotubes contiguous with the parent myofiber.
Myofiber branching negatively impacts dystrophic muscles as demonstrated using extensor digitorum longus (EDL) muscles from dystrophin-deficient mdx mice. Unbranched and branched myofibers isolated from mdx EDL muscles were subjected to Ca2+-force activation. Branched myofibers broke before reaching maximal calcium activation, whereas unbranched myofibers were able to sustain maximal force without any break . When EDL muscles from mdx mice were eccentrically contracted (EC), then incubated in Evans blue dye (EBD), approximately 70 % of the isolated branched myofibers showed EBD uptake at branch points indicating membrane damage, while no dye was observed in unbranched myofibers . Following Ca2+ osmotic stress, branched myofibers from mdx muscles also exhibited a higher number of osmotic-induced Ca2+ sparks than unbranched myofibers . Together, these data indicate that myofiber branching impairs multiple aspects of muscle physiology in dystrophic muscles. This leads to the question of how to reduce myofiber branching in dystrophic muscles in order to improve muscle physiology.
We recently identified mouse olfactory receptor 23 (mOR23, olfr16) as a molecule regulating myofiber branching in mouse muscles . Olfactory receptors (OR) are G protein-coupled receptors mainly found in neurons of the olfactory epithelium where they have been extensively studied, but they are also expressed in non-olfactory tissues such as the brain, tongue, testis, spleen, prostate, kidney, and smooth and skeletal muscle [8, 9]. OR serve as specialized chemosensors and are activated by exogenous ligands known as odorants in olfactory neurons or by endogenous ligands in non-olfactory tissues. Endogenous OR ligands have only been identified in non-olfactory tissues for olfr78 in the carotid body, kidney, peripheral vasculature, and prostate [9–11]. Mouse muscles electroporated with a plasmid expressing mOR23 under the control of a ubiquitous promoter contained fewer branched myofibers and fewer branches per myofiber . In the skeletal muscle, several types of cells are important for muscle regeneration such as neutrophils , macrophages , and fibroblasts  in addition to muscle stem cells . Since mOR23 was ubiquitously over-expressed, whether mOR23 was required specifically in muscle cells to regulate myofiber branching could not be addressed in these experiments. To directly address the role of mOR23 in muscle cells during myofiber branching, we created a novel transgenic mouse over-expressing mOR23 under the control of a specific muscle promoter . In-depth quantitative analyses of myofiber branching in these transgenic mice demonstrated that myofiber branching was reduced after chemically induced muscle injury. Subsequently, these mice were bred with mdx mice to determine whether muscle-specific over-expression of mOR23 was also beneficial in the context of repeated cycles of muscle degeneration/regeneration. We observed decreased myofiber branching in mdx mice over-expressing mOR23 resulting in less membrane damage of the dystrophic muscles after mechanical stress. Together, these results indicate that expression of mOR23 specifically in skeletal muscle is sufficient to decrease the incidence of myofiber branching after muscle injury.
Wild type (C57BL/6) and mdx (C57BL/10) mice were purchased from The Jackson Laboratory (Bar Harbor, ME, USA). To create mOR23 transgenic mice, the mOR23 gene was excised from pME-18S  using XbaI and BamHI restriction enzymes and ligated into pBSX-HSAvpA  previously cut with NotI and XbaI restriction enzymes. The resulting plasmid was named pHSA.mOR23 and cut using PvuI and KpnI restriction enzymes. The subsequent fragment was used by the Emory Transgenic Core to produce two independent lines of mOR23 transgenic mice, TG1 and TG2. TG1 was bred with mdx mice to create transgenic mdx mice over-expressing mOR23 (Tg-mdx). Female and male mice were used in all experiments at 8–12 weeks of age unless described otherwise. Experiments involving animals were performed in accordance with approved guidelines and ethical approval from Emory University’s and Georgia Institute of Technology’s Institutional Animal Care and Use Committees.
Quantitative real-time PCR
Total RNA from gastrocnemius muscles was isolated using TRIzol reagent (Invitrogen, Carlsbad, CA, USA) according to the manufacturer’s protocol. For each sample, 500 ng of RNA was digested with DNAseI (Invitrogen) to remove any DNA contaminants and cDNA synthesis was performed by M-MLV reverse-transcriptase (Invitrogen). Using a real-time (RT) PCR system (StepOnePlus, Applied Biosystem, Foster City, CA, USA), the relative levels of mOR23 were determined by the ΔΔCt method  and normalized to the housekeeping gene HPRT1. Primers were purchased from SA Biosciences (Valencia, CA, USA) (mOR23: PPM60724B, HPRT1: PPM03559E). All reactions were performed in duplicate.
Mice were anesthetized with an intraperitoneal injection of a solution containing 80 mg/kg ketamine HCl/5 mg/kg xylazine and subcutaneously injected with an analgesic (0.1 mg/kg buprenorphine) before and after muscle injury. Injury was induced in gastrocnemius muscles of anesthetized mice by injection of 40 μl of 1.2 % BaCl2 . Muscles were collected 2–3 weeks after the injury and either snap frozen in liquid nitrogen or enzymatically digested for isolation of single myofibers.
The day before the eccentric contraction protocol, mice were intraperitoneally injected with EBD (Sigma-Aldrich) (100 μL of 1 % EBD in PBS per 10-g body weight). The following day, mice were anesthetized by intraperitoneal injection of a ketamine/xylazine cocktail (90 mg/kg ketamine, 15 mg/ml xylazine), with supplemental doses as necessary. The left plantaris and soleus muscles were ablated and a 4-0 suture tied around the Achilles tendon at the calcaneus. The insertion of the tendon was clipped from the calcaneus, leaving a small bone chip to anchor the suture. The knee was immobilized by a spring clamp fixed to the femoral condyles, and the gastrocnemius complex was attached to a force-reporting servo motor (Aurora Scientific, Aurora, ON, Canada). The sciatic nerve was exposed and mounted on bipolar stainless steel hook electrodes. A series of twitch contractions was used to determine the stimulation voltage and muscle length (L 0) required for maximal active force production. Muscles were stimulated using constant current, determined for each animal as twice the current required (700–1500 uA) to yield maximum twitch force. L 0 was determined from twitches by adjusting the muscle length to maximize active tension. The lengthening activation protocol consisted of 300 stimulations, each 500 ms of 0.1-ms pulses delivered at 70 Hz and 2× maximal voltage. The muscle was held isometric for 200 ms at L 0 − 10 % optimal fiber length (L f), stretched to L 0 + 10 % L f over 200 ms, and held for 200 ms. The muscle was returned to L 0 − 10 % L f after relaxation with 500-ms rest between activations. At the end of the protocol, muscles were collected and snap frozen in liquid nitrogen.
Single myofiber isolation
Single myofibers were isolated from gastrocnemius muscles as previously described . Briefly, muscles were gently dissected, added to a tube containing 4000 U collagenase type I (Worthington Biochemical, Lakewood Township, NJ, USA). The tube was rocked at 26 rpm in an Enviro-Genie (Scientific Industries, Bohemia, NY, USA) set at 37 °C. Wild type muscles were digested for 90 min and for up to 120 min for mdx and Tg-mdx muscles. After incubation in collagenase, single myofibers were washed and transferred into a Matrigel (BD Pharmigen, San Diego, CA, USA)-coated 24-well plate using a fire-polished Pasteur pipette. Isolated myofibers were allowed to settle for 30 min in the well before the plates were centrifuged at 1100g for 20 min and then fixed with 3.7 % formaldehyde for 10 min. A total of 471 and 475 myofibers were isolated for mdx and Tg-mdx mice, respectively, and between 496 and 828 for wild type ( WT), TG1, and TG2 BaCl2-injured mice.
Single myofiber analysis
Single myofibers were stained with 1 μg/ml 4′,6-diamidino-2-phenylindole (DAPI, Sigma-Aldrich, St Louis, MO, USA) for 1 min to visualize nuclei. Myofibers were visualized using an Axiovert 200M microscope (Carl Zeiss Microscopy, Thornwood, NY, USA), and images were acquired using a 10× or 20× Plan-Neofluar objective (Carl Zeiss Microscopy) and camera (QImaging, Surrey, BC, Canada) with OpenLab 5.50 software (PerkinElmer, Waltham, MA, USA). All images were uniformly processed for size, brightness, and contrast using Photoshop CS6 (Adobe Systems, San Jose, CA, USA). Myofibers with at least four centrally located nuclei in a row were considered regenerated. Branches were grouped into three morphologic categories: bifurcated, split, and process although the significance of these different types of branches is not well understood [6, 20, 21].
Serial 12-μm cryostat sections were obtained throughout frozen muscles. For histological analyses, sections were stained with hematoxylin (Thermo Fisher Scientific, Waltham, MA, USA) and eosin (Sigma-Aldrich) stained sections using ImageJ (NIH, Bethesda, MD, USA). For all tissue section studies, three to four representative sections imaged at ×200 magnification were analyzed from gastrocnemius muscles. For EBD quantification, images were acquired from the same anatomic region in three to four different sections and the EBD fluorescence of each image was measured as pixel intensity using Image J. All images were acquired using an Axioplan microscope with a 0.5 NA 20× Plan-Neofluar objective (Carl Zeiss Microscopy) and charge-coupled device camera (Carl Zeiss Microscopy) with Scion Image 1.63 (Scion Corporation, Frederick, MD, USA). All images were uniformly processed for size, brightness, and contrast using Photoshop CS6 (Adobe).
To determine statistical significance for two groups, comparisons were made using an unpaired or paired Student’s t test. Chi-square tests were performed for the analysis of the number of branches per myofiber. The significance of results from multiple groups was evaluated by a one-way analysis of variance (ANOVA) with Bonferroni’s post-test. The Friedman test with Dunn’s post-test was used to analyze EBD fluorescence in muscle sections. Statistical analyses were performed using GraphPad Prism v.6 (GraphPad Software, La Jolla, CA, USA). A p value <0.05 was considered significant.
mOR23 transgenic mice
Analysis of myofiber branching in isolated myofibers
Muscle-specific expression of mOR23 decreases myofiber branching in chemically injured mouse muscles
mOR23 over-expression reduces myofiber branching in dystrophic mouse muscles
mOR23 over-expression protects dystrophic muscle against mechanical damage
The results reported here expand previous studies of mOR23 in muscle tissue  and give insights into the formation of branched myofibers, which are detrimental for normal muscle physiology. One significant finding of this study is that following acute muscle injury, myofiber branching was decreased in transgenic mice over-expressing mOR23 specifically in muscle cells. Depending on the level of mOR23 over-expression, the number of branches per branched myofiber was also reduced. These results suggest that putative endogenous ligand(s) of mOR23 [7, 29] produced in response to muscle damage were not limiting under these conditions. Another important finding is that when mOR23 was over-expressed in myofibers in a dystrophic environment with ongoing cycles of myofiber degeneration/regeneration, myofiber branching was also decreased. These are the first studies to show that myofiber branching can be decreased in dystrophic muscles. Depending on the amount of damage that occurred in dystrophic mice with age, the parameters of the myofiber branching varied. At 8 weeks of age, dystrophic muscles were characterized by a reduction in the percentage of branched myofibers as well as a decrease of the number of branches per branched myofiber. However, at 15 weeks of age only the number of branches per branched myofiber was decreased. These differences could be due to changes in the production of putative endogenous mOR23 ligand(s) or to derangements in cell signaling pathways with age in dystrophic mice [30, 31]. Taken together our data indicate that mOR23 over-expression in muscle cells is sufficient to reduce myofiber branching in mice suggesting that biologic processes acting within muscle cells are important for determining whether branches form or not upon muscle injury.
Previous studies of dystrophic muscles indicated that myofiber branching is detrimental for normal muscle physiology [5, 6, 21, 27, 28]. Branched myofibers tends to break at the branch point thereby decreasing the ability of myofibers to properly contract [5, 21]. Another key finding in our studies was that a decrease of myofiber branching in dystrophic muscle via the over-expression of mOR23 in muscle cells improved membrane integrity in response to mechanical stress induced by a stretch of eccentric contractions. These results suggest that modifying myofiber branching in dystrophic patients, while not preventing degeneration, could be beneficial for mitigating some of the effects of the disease process. Such a therapy could be used in combination with other disease-modifying strategies currently under development [32, 33].
Olfactory receptor activation leads to an increase in cyclic adenosine monophosphate (cAMP) synthesis through the activation of adenylate cyclase type III via a G protein-coupled cascade in the neurons , sperm , and kidney  as well as skeletal muscle . In olfactory neurons, this increase in cAMP can regulate expression of adhesion molecules such as Kirrel3 or EphrinA5 , neuropilin-1 which plays versatile roles in angiogenesis, cell survival and migration , and multiple ion channels . Myofiber branching has been postulated to arise from aberrant muscle cell fusion [6, 20, 21, 38]. Previous studies of mOR23 function in vitro revealed that cell migration, cell-cell adhesion, and formation of multinucleated myotubes were significantly inhibited with loss of mOR23 by small interfering RNA (siRNA) or increased by its over-expression  suggesting that mOR23 may regulate cell fusion through downstream migration and adhesion molecules. However, no downstream effectors of mOR23 in vitro or in vivo have been identified to date.
mOR23 signaling within muscle cells may serve as an effective pharmacologic target for improving muscle architecture and physiology in dystrophic patients. The use of small molecules to activate downstream processes normally induced by mOR23 signaling in muscle cells could overcome any potential limitations in the amount of putative endogenous ligand(s) produced at different stages of the dystrophic disease process. Additional studies are needed to identify other molecules and pathways that synergize with mOR23-dependent pathways to further decrease myofiber branching in dystrophic muscles.
cyclic adenosine monophosphate
Duchenne muscular dystrophy
Evans blue dye
extensor digitorum longus
human skeletal actin
mouse olfactory receptor
pBSX-HSAvpA is a gift from Dr. Jeff Chamberlain via Dr. Edna Hardeman. This work was supported by grants to GKP from the Muscular Dystrophy Association (#186852) and NIH (AR061267).
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Hoffman EP, Brown Jr RH, Kunkel LM. Dystrophin: the protein product of the Duchenne muscular dystrophy locus. Cell. 1987;51(6):919–28.PubMedView ArticleGoogle Scholar
- Bushby K, Finkel R, Birnkrant DJ, Case LE, Clemens PR, Cripe L, et al. Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and pharmacological and psychosocial management. Lancet Neurol. 2010;9(1):77–93. doi:10.1016/S1474-4422(09)70271-6.PubMedView ArticleGoogle Scholar
- Swash M, Schwartz MS. Implications of longitudinal muscle fibre splitting in neurogenic and myopathic disorders. J Neurol Neurosurg Psychiatry. 1977;40(12):1152–9.PubMedPubMed CentralView ArticleGoogle Scholar
- Ontell M. Muscle fiber necrosis in murine dystrophy. Muscle Nerve. 1981;4(3):204–13. doi:10.1002/mus.880040306.PubMedView ArticleGoogle Scholar
- Head SI. Branched fibres in old dystrophic mdx muscle are associated with mechanical weakening of the sarcolemma, abnormal Ca2+ transients and a breakdown of Ca2+ homeostasis during fatigue. Exp Physiol. 2010;95(5):641–56. doi:10.1113/expphysiol.2009.052019.PubMedView ArticleGoogle Scholar
- Lovering RM, Michaelson L, Ward CW. Malformed mdx myofibers have normal cytoskeletal architecture yet altered EC coupling and stress-induced Ca2+ signaling. Am J Physiol Cell Physiol. 2009;297(3):C571–80. doi:10.1152/ajpcell.00087.2009.PubMedPubMed CentralView ArticleGoogle Scholar
- Griffin CA, Kafadar KA, Pavlath GK. MOR23 promotes muscle regeneration and regulates cell adhesion and migration. Dev Cell. 2009;17(5):649–61. doi:10.1016/j.devcel.2009.09.004.PubMedPubMed CentralView ArticleGoogle Scholar
- Kang N, Koo J. Olfactory receptors in non-chemosensory tissues. BMB Rep. 2012;45(11):612–22.PubMedPubMed CentralView ArticleGoogle Scholar
- Pluznick JL, Protzko RJ, Gevorgyan H, Peterlin Z, Sipos A, Han J, et al. Olfactory receptor responding to gut microbiota-derived signals plays a role in renin secretion and blood pressure regulation. Proc Natl Acad Sci U S A. 2013;110(11):4410–5. doi:10.1073/pnas.1215927110.PubMedPubMed CentralView ArticleGoogle Scholar
- Neuhaus EM, Zhang W, Gelis L, Deng Y, Noldus J, Hatt H. Activation of an olfactory receptor inhibits proliferation of prostate cancer cells. J Biol Chem. 2009;284(24):16218–25. doi:10.1074/jbc.M109.012096.PubMedPubMed CentralView ArticleGoogle Scholar
- Chang AJ, Ortega FE, Riegler J, Madison DV, Krasnow MA. Oxygen regulation of breathing through an olfactory receptor activated by lactate. Nature. 2015;527(7577):240–4. doi:10.1038/nature15721.PubMedView ArticleGoogle Scholar
- Teixeira CF, Zamuner SR, Zuliani JP, Fernandes CM, Cruz-Hofling MA, Fernandes I, et al. Neutrophils do not contribute to local tissue damage, but play a key role in skeletal muscle regeneration, in mice injected with Bothrops asper snake venom. Muscle Nerve. 2003;28(4):449–59. doi:10.1002/mus.10453.PubMedView ArticleGoogle Scholar
- Chazaud B, Sonnet C, Lafuste P, Bassez G, Rimaniol AC, Poron F, et al. Satellite cells attract monocytes and use macrophages as a support to escape apoptosis and enhance muscle growth. J Cell Biol. 2003;163(5):1133–43. doi:10.1083/jcb.200212046.PubMedPubMed CentralView ArticleGoogle Scholar
- Murphy MM, Lawson JA, Mathew SJ, Hutcheson DA, Kardon G. Satellite cells, connective tissue fibroblasts and their interactions are crucial for muscle regeneration. Development. 2011;138(17):3625–37. doi:10.1242/dev.064162.PubMedPubMed CentralView ArticleGoogle Scholar
- Moss FP, Leblond CP. Satellite cells as the source of nuclei in muscles of growing rats. Anat Rec. 1971;170(4):421–35. doi:10.1002/ar.1091700405.PubMedView ArticleGoogle Scholar
- Crawford GE, Faulkner JA, Crosbie RH, Campbell KP, Froehner SC, Chamberlain JS. Assembly of the dystrophin-associated protein complex does not require the dystrophin COOH-terminal domain. J Cell Biol. 2000;150(6):1399–410.PubMedPubMed CentralView ArticleGoogle Scholar
- Katada S, Nakagawa T, Kataoka H, Touhara K. Odorant response assays for a heterologously expressed olfactory receptor. Biochem Biophys Res Commun. 2003;305(4):964–9.PubMedView ArticleGoogle Scholar
- Muscat GE, Kedes L. Multiple 5′-flanking regions of the human alpha-skeletal actin gene synergistically modulate muscle-specific expression. Mol Cell Biol. 1987;7(11):4089–99.PubMedPubMed CentralView ArticleGoogle Scholar
- Livak KJ, Schmittgen TD. Analysis of relative gene expression data using real-time quantitative PCR and the 2(−delta delta C(T)) method. Methods. 2001;25(4):402–8. doi:10.1006/meth.2001.1262.PubMedView ArticleGoogle Scholar
- Pichavant C, Pavlath GK. Incidence and severity of myofiber branching with regeneration and aging. Skelet Muscle. 2014;4:9. doi:10.1186/2044-5040-4-9.PubMedPubMed CentralView ArticleGoogle Scholar
- Chan S, Head SI. The role of branched fibres in the pathogenesis of Duchenne muscular dystrophy. Exp Physiol. 2011;96(6):564–71. doi:10.1113/expphysiol.2010.056713.PubMedView ArticleGoogle Scholar
- Schmalbruch H. The morphology of regeneration of skeletal muscles in the rat. Tissue Cell. 1976;8(4):673–92.PubMedView ArticleGoogle Scholar
- Sadeh M, Czyewski K, Stern LZ. Chronic myopathy induced by repeated bupivacaine injections. J Neurol Sci. 1985;67(2):229–38.PubMedView ArticleGoogle Scholar
- Head SI, Houweling PJ, Chan S, Chen G, Hardeman EC. Properties of regenerated mouse extensor digitorum longus muscle following notexin injury. Exp Physiol. 2014;99(4):664–74. doi:10.1113/expphysiol.2013.077289.PubMedView ArticleGoogle Scholar
- McGeachie JK, Grounds MD, Partridge TA, Morgan JE. Age-related changes in replication of myogenic cells in mdx mice: quantitative autoradiographic studies. J Neurol Sci. 1993;119(2):169–79.PubMedView ArticleGoogle Scholar
- Roig M, Roma J, Fargas A, Munell F. Longitudinal pathologic study of the gastrocnemius muscle group in mdx mice. Acta Neuropathol. 2004;107(1):27–34. doi:10.1007/s00401-003-0773-3.PubMedView ArticleGoogle Scholar
- Chan S, Head SI, Morley JW. Branched fibers in dystrophic mdx muscle are associated with a loss of force following lengthening contractions. Am J Physiol Cell Physiol. 2007;293(3):C985–92. doi:10.1152/ajpcell.00128.2007.PubMedView ArticleGoogle Scholar
- Hernandez-Ochoa EO, Pratt SJ, Garcia-Pelagio KP, Schneider MF, Lovering RM. Disruption of action potential and calcium signaling properties in malformed myofibers from dystrophin-deficient mice. Physiological reports. 2015;3(4). doi:10.14814/phy2.12366.
- Fukuda N, Yomogida K, Okabe M, Touhara K. Functional characterization of a mouse testicular olfactory receptor and its role in chemosensing and in regulation of sperm motility. J Cell Sci. 2004;117(Pt 24):5835–45. doi:10.1242/jcs.01507.PubMedView ArticleGoogle Scholar
- Reynolds JG, McCalmon SA, Donaghey JA, Naya FJ. Deregulated protein kinase A signaling and myospryn expression in muscular dystrophy. J Biol Chem. 2008;283(13):8070–4. doi:10.1074/jbc.C700221200.PubMedPubMed CentralView ArticleGoogle Scholar
- Jiang C, Wen Y, Kuroda K, Hannon K, Rudnicki MA, Kuang S. Notch signaling deficiency underlies age-dependent depletion of satellite cells in muscular dystrophy. Dis Model Mech. 2014;7(8):997–1004. doi:10.1242/dmm.015917.PubMedPubMed CentralView ArticleGoogle Scholar
- Benedetti S, Cossu G, Tedesco FS. Gene and cell therapies for muscular dystrophies. In: Templeton NS, editor. Gene and cell therapy: therapeutic mechanisms and strategies. 4th ed. New York: Marcel Dekker; 2015. p. 993–1015.Google Scholar
- Guiraud S, Chen H, Burns DT, Davies KE. Advances in genetic therapeutic strategies for Duchenne muscular dystrophy. Experimental physiology. 2015. doi:10.1113/EP085308
- Spehr M, Gisselmann G, Poplawski A, Riffell JA, Wetzel CH, Zimmer RK, et al. Identification of a testicular odorant receptor mediating human sperm chemotaxis. Science. 2003;299(5615):2054–8. doi:10.1126/science.1080376.PubMedView ArticleGoogle Scholar
- Pluznick JL, Zou DJ, Zhang X, Yan Q, Rodriguez-Gil DJ, Eisner C, et al. Functional expression of the olfactory signaling system in the kidney. Proc Natl Acad Sci U S A. 2009;106(6):2059–64. doi:10.1073/pnas.0812859106.PubMedPubMed CentralView ArticleGoogle Scholar
- Serizawa S, Miyamichi K, Takeuchi H, Yamagishi Y, Suzuki M, Sakano H. A neuronal identity code for the odorant receptor-specific and activity-dependent axon sorting. Cell. 2006;127(5):1057–69. doi:10.1016/j.cell.2006.10.031.PubMedView ArticleGoogle Scholar
- Imai T, Suzuki M, Sakano H. Odorant receptor-derived cAMP signals direct axonal targeting. Science. 2006;314(5799):657–61. doi:10.1126/science.1131794.PubMedView ArticleGoogle Scholar
- Robertson TA, Papadimitriou JM, Grounds MD. Fusion of myogenic cells to the newly sealed region of damaged myofibres in skeletal muscle regeneration. Neuropathol Appl Neurobiol. 1993;19(4):350–8.PubMedView ArticleGoogle Scholar