Steep Increase in Myonuclear Domain Size During Infancy

Abstract

We investigated whether myonuclear number increases in proportion to the increase in fiber size during maturational growth of skeletal muscle. Thoraco-abdominal muscle tissue was obtained from twenty 6-day to 15-year-old boys and girls during cardiothoracic surgery. Cross-sections were stained by anti-laminin for the basal lamina and by DAPI to identify nuclei. Basal lamina was traced on digital images to measure the fiber cross-sectional area (FCSA). Nuclei located within the basal lamina were considered myonuclei if pax7-negative and satellite cell nuclei if pax7-positive. Samples of two children were excluded from analysis because of clear signs of hypoxia as shown by positive carbonic anhydrase IX staining. Linear regression showed that FCSA increased with age by 187 lm 2 Áper annum (R 2 ¼ 0.90; P < 0.001). Satellite cell density showed a dramatic decrease in the first months of life, but this was not accompanied by an increase in myonuclei per muscle fiber cross-section. Till four years of age the number of myonuclei per muscle fiber cross-section remained relatively constant but increased thereafter. Myonuclear domain size showed a steep increase during infancy and reached adult values in the young adolescent phase.

Rev-erb-α modulates skeletal muscle oxidative capacity by regulating mitochondrial biogenesis and autophagy

“…After incubation with the appropriate fluorescent-labeled secondary antibodies (Goat anti-rabbit IgG AlexaFluor 555 for CD31, Goat anti-mouse IgG1 AlexaFluor488 for Pax7, Goat anti-rabbit IgG AlexaFluor350 for laminin and Goat Anti-mouse IgM AlexaFlur488 for A4.840, all from InVitrogen/Moleculr Probes) and DAPI-stain (30 nM, Invitrogen) for nuclei, sections were mounted in Mowiol. Images were captured with a Nikon E800 fluorescence microscope 44 .…”

Satellite cells in human skeletal muscle plasticity

“…In animal studies, the Pax7 antigen is the most widely used marker to identify satellite cells (Olguin and Olwin, 2004 ; Kuang et al, 2006 ; Relaix et al, 2006 ; Zammit et al, 2006 ; Day et al, 2007 ; Ishido et al, 2009 ; Lepper et al, 2011 ; McCarthy et al, 2011 ; Murphy et al, 2011 ; Sambasivan et al, 2011 ; Jackson et al, 2012 ) and has been proposed to be the most reliable marker for satellite cells in mouse muscle (Kuang and Rudnicki, 2008 ; Zammit, 2008 ). In the past decade, an increasing number of human studies have utilized the Pax7 antibody for the identification of skeletal muscle satellite cells in vivo (McLoon and Wirtschafter, 2003 ; Reimann et al, 2004 ; Verdijk et al, 2007 ; McKay et al, 2008 ; Mackey et al, 2009 ; McKay et al, 2009 ; Kottlors and Kirschner, 2010 ; McKay et al, 2010 ; Mackey et al, 2011a ; Toth et al, 2011 ; McKay et al, 2012 ; Menon et al, 2012 ; Nielsen et al, 2012 ; Theriault et al, 2012 ; Walker et al, 2012 ; Bankole et al, 2013 ; Cermak et al, 2013 ; Delhaas et al, 2013 ; Joanisse et al, 2013 ; McKay et al, 2013 ; Suetta et al, 2013 ; Bellamy et al, 2014 ; Farup et al, 2014a , b ; Fry et al, 2014a ; Grubb et al, 2014 ; Kern et al, 2014 ; Mackey et al, 2014 ; Snijders et al, 2014b , c ; Theriault et al, 2014 ). Reimann et al ( 2004 ) compared M-Cad and Pax7 in biopsies taken from healthy and pathological human muscle.…”

Skeletal Muscle Degeneration and Regeneration in Mice and Flies

“…During this stage there is extensive fusion of myoblasts into the elongating growing myofibers (hyperplasia), but after this time the increasing myofiber size is due mainly to hypertrophy (with minimal change in myonuclear number) ( Fig. However, an interesting recent paper (Delhaas, Van der Meer, Schaart, Degens, & Drost, 2013) investigated this aspect of myonuclear domain size in growing thoracoabdominal muscles of humans (aged 0.2 months to 15 years) and concluded that satellite cell density steeply declines in early infancy. The reason for this striking transition from hyperplasia to hypertrophy during growth is not known and has not been widely investigated for other species.…”

“…9.3B) (White et al, 2010). As a result, the myonuclear domain area [mm 2 ] increases rapidly in the first months after birth and reaches adult values in the young adolescent phase (Delhaas et al, 2013). However, an interesting recent paper (Delhaas, Van der Meer, Schaart, Degens, & Drost, 2013) investigated this aspect of myonuclear domain size in growing thoracoabdominal muscles of humans (aged 0.2 months to 15 years) and concluded that satellite cell density steeply declines in early infancy.…”