Quantifying the temporospatial expression of postnatal porcine skeletal myosin heavy chain genes.
Postnatal skeletal muscle fiber type is commonly defined by one of four major myosin heavy chain (MyHC) gene isoforms (slow/I, 2a, 2x, and 2b) that are expressed. We report on the novel use of combined TaqMan quantitative real-time RT-PCR and image analysis of serial porcine muscle sections, subjected to in situ hybridization (ISH) and immunocytochemistry (IHC), to quantify the mRNA expression of each MyHC isoform within its corresponding fiber type, termed relative fiber type-restricted expression. This versatile approach will allow quantitative temporospatial comparisons of each MyHC isoform among muscles from the same or different individuals. Using this approach on porcine skeletal muscles, we found that the relative fiber type-restricted expression of each postnatal MyHC gene showed wide spatial and temporal variation within a given muscle and between muscles. Marked differences were also observed among pig breeds. Notably, of the four postnatal MyHC isoforms, the 2a MyHC gene showed the highest relative fiber type-restricted expression in each muscle examined, regardless of age, breed, or muscle type. This suggests that although 2a fibers are a minor fiber type, they may be disproportionately more important as a determinant of overall muscle function than was previously believed.
da Costa
Nuno
N
Veterinary Molecular Medicine Laboratory, Department of Veterinary Pathology, University of Glasgow, Glasgow, Scotland.
Blackley
Ross
R
Alzuherri
Hadi
H
Chang
Kin-Chow
KC
D000199:Actins / Q000235:genetics; D000375:Aging; D000818:Animals; D015870:Gene Expression; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000378:metabolism; D018482:Muscle, Skeletal / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics; D015347:RNA Probes; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013045:Species Specificity; D013552:Swine / Q000254:growth & development* / Q000378:metabolism
D000199:Actins; D020033:Protein Isoforms; D015347:RNA Probes; D012333:RNA, Messenger; D018995:Myosin Heavy Chains