Muscle regeneration in dystrophin-deficient mdx mice studied by gene expression profiling.
BACKGROUND
Duchenne muscular dystrophy (DMD), caused by mutations in the dystrophin gene, is lethal. In contrast, dystrophin-deficient mdx mice recover due to effective regeneration of affected muscle tissue. To characterize the molecular processes associated with regeneration, we compared gene expression levels in hindlimb muscle tissue of mdx and control mice at 9 timepoints, ranging from 1-20 weeks of age.


RESULTS
Out of 7776 genes, 1735 were differentially expressed between mdx and control muscle at at least one timepoint (p < 0.05 after Bonferroni correction). We found that genes coding for components of the dystrophin-associated glycoprotein complex are generally downregulated in the mdx mouse. Based on functional characteristics such as membrane localization, signal transduction, and transcriptional activation, 166 differentially expressed genes with possible functions in regeneration were analyzed in more detail. The majority of these genes peak at the age of 8 weeks, where the regeneration activity is maximal. The following pathways are activated, as shown by upregulation of multiple members per signalling pathway: the Notch-Delta pathway that plays a role in the activation of satellite cells, and the Bmp15 and Neuregulin 3 signalling pathways that may regulate proliferation and differentiation of satellite cells. In DMD patients, only few of the identified regeneration-associated genes were found activated, indicating less efficient regeneration processes in humans.


CONCLUSIONS
Based on the observed expression profiles, we describe a model for muscle regeneration in mdx mice, which may provide new leads for development of DMD therapies based on the improvement of muscle regeneration efficacy.
Turk
R
R
Center for Human and Clinical Genetics, Leiden University Medical Center, Wassenaarseweg 72, 2333 AL Leiden, Nederland. rolf-turk@uiowa.edu
Sterrenburg
E
E
de Meijer
E J
EJ
van Ommen
G-J B
GJ
den Dunnen
J T
JT
't Hoen
P A C
PA
D000293:Adolescent; D000818:Animals; D055430:Bone Morphogenetic Protein 15; D002648:Child; D016000:Cluster Analysis; D015536:Down-Regulation; D029721:Drosophila Proteins / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D055429:Growth Differentiation Factor 9; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D008954:Models, Biological; D009132:Muscles / Q000473:pathology / Q000502:physiology*; D020388:Muscular Dystrophy, Duchenne / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D020880:Neuregulins; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D009841:Oligonucleotides / Q000737:chemistry; D012313:RNA / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D012038:Regeneration; D020133:Reverse Transcriptase Polymerase Chain Reaction; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D015854:Up-Regulation
C525901:BMP15 protein, human; C525902:Bmp15 protein, mouse; D055430:Bone Morphogenetic Protein 15; D029721:Drosophila Proteins; C525897:GDF9 protein, human; C525898:Gdf9 protein, mouse; D055429:Growth Differentiation Factor 9; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; C497759:N protein, Drosophila; D020880:Neuregulins; C108113:Nrg3 protein, mouse; D009841:Oligonucleotides; D051880:Receptors, Notch; D012313:RNA