INTRODUCTION: Contradictory reports of the myosin heavy chain (MHC) composition of adult human suprahyoid muscles leave unresolved the extent to which these muscles express developmental and unconventional MHC. METHODS: By immunohistochemistry, separation sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-Coomassie, separation SDS-PAGE-Western blot, and mRNA PCR, we tested for conventional MHCI, MHCIIA, MHCIIX, developmental MHC embryonic and MHC neonatal, and unconventional MHC alpha-cardiac, MHC extraocular, and MHC slow tonic in adult human anterior digastric (AD), geniohyoid (GH), and mylohyoid (MH) muscles. RESULTS: By separation SDS-PAGE-Coomassie and Western blot, only conventional MHC are present. By immunohistochemistry all muscle fibers are positive for MHCI, MHCIIA, or MHCIIX, and fewer than 4 fibers/mm(2) are positive for developmental or unconventional MHC. By PCR, mRNA of MHCI and MHCIIA dominate, with sporadically detectable MHC alpha-cardiac and without detectable mRNA of other developmental and unconventional MHC. CONCLUSIONS: We conclude that human suprahyoid muscles AD, GH, and MH are composed almost exclusively of conventional MHC isoforms.
INTRODUCTION: Contradictory reports of the myosin heavy chain (MHC) composition of adult human suprahyoid muscles leave unresolved the extent to which these muscles express developmental and unconventional MHC. METHODS: By immunohistochemistry, separation sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-Coomassie, separation SDS-PAGE-Western blot, and mRNA PCR, we tested for conventional MHCI, MHCIIA, MHCIIX, developmental MHC embryonic and MHC neonatal, and unconventional MHC alpha-cardiac, MHC extraocular, and MHC slow tonic in adult human anterior digastric (AD), geniohyoid (GH), and mylohyoid (MH) muscles. RESULTS: By separation SDS-PAGE-Coomassie and Western blot, only conventional MHC are present. By immunohistochemistry all muscle fibers are positive for MHCI, MHCIIA, or MHCIIX, and fewer than 4 fibers/mm(2) are positive for developmental or unconventional MHC. By PCR, mRNA of MHCI and MHCIIA dominate, with sporadically detectable MHC alpha-cardiac and without detectable mRNA of other developmental and unconventional MHC. CONCLUSIONS: We conclude that human suprahyoid muscles AD, GH, and MH are composed almost exclusively of conventional MHC isoforms.
Authors: William G Pearson; David F Hindson; Susan E Langmore; Ann C Zumwalt Journal: Int J Radiat Oncol Biol Phys Date: 2012-09-18 Impact factor: 7.038