title: Microgenomic analysis in skeletal muscle: expression signatures of individual fast and slow myofibers.
abstract: BACKGROUND
  Skeletal muscle is a complex, versatile tissue composed of a variety of functionally diverse fiber types. Although the biochemical, structural and functional properties of myofibers have been the subject of intense investigation for the last decades, understanding molecular processes regulating fiber type diversity is still complicated by the heterogeneity of cell types present in the whole muscle organ.
  
  
  RESULTS
  We have produced a first catalogue of genes expressed in mouse slow-oxidative (type 1) and fast-glycolytic (type 2B) fibers through transcriptome analysis at the single fiber level (microgenomics). Individual fibers were obtained from murine soleus and EDL muscles and initially classified by myosin heavy chain isoform content. Gene expression profiling on high density DNA oligonucleotide microarrays showed that both qualitative and quantitative improvements were achieved, compared to results with standard muscle homogenate. First, myofiber profiles were virtually free from non-muscle transcriptional activity. Second, thousands of muscle-specific genes were identified, leading to a better definition of gene signatures in the two fiber types as well as the detection of metabolic and signaling pathways that are differentially activated in specific fiber types. Several regulatory proteins showed preferential expression in slow myofibers. Discriminant analysis revealed novel genes that could be useful for fiber type functional classification.
  
  
  CONCLUSIONS
  As gene expression analyses at the single fiber level significantly increased the resolution power, this innovative approach would allow a better understanding of the adaptive transcriptomic transitions occurring in myofibers under physiological and pathological conditions.
authors.affiliation: Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Chemello
authors.forename: Camilla
authors.initials: C
authors.lastname: Bean
authors.forename: Pasqua
authors.initials: P
authors.lastname: Cancellara
authors.forename: Paolo
authors.initials: P
authors.lastname: Laveder
authors.forename: Carlo
authors.initials: C
authors.lastname: Reggiani
authors.forename: Gerolamo
authors.initials: G
authors.lastname: Lanfranchi
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D005240:Feasibility Studies; D020869:Gene Expression Profiling / Q000379:methods; D023281:Genomics / Q000379:methods*; D008297:Male; D051379:Mice; D008832:Microchemistry / Q000379:methods*; D008904:Miniaturization / Q000379:methods; D018656:Muscle Fibers, Fast-Twitch / Q000737:chemistry / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000737:chemistry / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism
chemical_list: D020033:Protein Isoforms