caa a22 4500 475744861 CHVBK 20180406123510.0 cr unu---uuuuu 170329e20001001xx s 000 0 eng 10.1023/A:1005683825960 doi (NATIONALLICENCE)springer-10.1023/A:1005683825960 The expression of the myogenic regulatory factors in denervated and normal muscles of different phenotypes [Elektronische Daten] [E. Walters, N. Stickland, P. Loughna] The nerve is known to play a pivotal role in the diversification of muscle fibre types postnatally. Reducing neuronal activity in a slow muscle such as the soleus by denervation, switches on genes associated with a fast muscle phenotype. On the other hand, denervating a fast muscle such as the extensor digitorum longus (EDL) induces the conversion of fast fibres to a ‘slower' contractile phenotype. The myogenic regulatory factors (MRFs) are proposed as the regulators of muscle phenotype as MyoD and myogenin have been shown to differentially accumulate in fast and slow muscle upon the induction of fibre type transformation. The denervation model has been used in the present study to induce changes in MRF expression in the muscles of the lower hindlimb which have distinct phenotypic characteristics. The level of MRF expression in pairs of denervated and innervated soleus, EDL, tibialis anterior (TA), plantaris and gastrocnemius muscles has been determined by Northern analysis and compared. The present study has shown that each muscle responds differently to denervation with respect to the increases in MRF expression. Fast muscles responded very quickly to denervation by increasing the level of MRF transcripts while slow muscles did not show significant increases in expression after 48 h denervation. The innervated EDL (fast) and soleus (slow) muscle differed with respect to the level of MRF-4 expressed, MRF-4 being expressed at higher levels in the slow muscle compared to the fast, suggesting that MRF-4 is important in the maintenance of a slow muscle phenotype. Moreover, MRF-4 and myogenin show the greatest fold increases in expression in the fast muscles examined. MyoD and Myf 5 show less dramatic increase in expression in response to denervation but exhibit the greatest fold increases in the fast muscles compared to slow. Kluwer Academic Publishers, 2000 Walters E. Department of Veterinary Basic Sciences, The Royal Veterinary College, University of London, Royal College St., NW1 0TU, London, UK aut Stickland N. Department of Veterinary Basic Sciences, The Royal Veterinary College, University of London, Royal College St., NW1 0TU, London, UK aut Loughna P. Department of Veterinary Basic Sciences, The Royal Veterinary College, University of London, Royal College St., NW1 0TU, London, UK aut Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/7(2000-10-01), 647-653 0142-4319 21:7<647 2000 21 10974 https://doi.org/10.1023/A:1005683825960 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1005683825960 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Walters E. Department of Veterinary Basic Sciences, The Royal Veterinary College, University of London, Royal College St., NW1 0TU, London, UK aut NATIONALLICENCE 700 1- Stickland N. Department of Veterinary Basic Sciences, The Royal Veterinary College, University of London, Royal College St., NW1 0TU, London, UK aut NATIONALLICENCE 700 1- Loughna P. Department of Veterinary Basic Sciences, The Royal Veterinary College, University of London, Royal College St., NW1 0TU, London, UK aut NATIONALLICENCE 773 0- Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/7(2000-10-01), 647-653 0142-4319 21:7<647 2000 21 10974 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer