Differential requirement for satellite cells during overload-induced muscle hypertrophy in growing versus mature mice.

ABSTRACT:

Background

Pax7+ satellite cells are required for skeletal muscle fiber growth during post-natal development in mice. Satellite cell-mediated myonuclear accretion also appears to persist into early adulthood. Given the important role of satellite cells during muscle development, we hypothesized that the necessity of satellite cells for adaptation to an imposed hypertrophic stimulus depends on maturational age.

Methods

Pax7^CreER-R26R^DTA mice were treated for 5 days with vehicle (satellite cell-replete, SC+) or tamoxifen (satellite cell-depleted, SC-) at 2 months (young) and 4 months (mature) of age. Following a 2-week washout, mice were subjected to sham surgery or 10 day synergist ablation overload of the plantaris (n?=?6-9 per group). The surgical approach minimized regeneration, de novo fiber formation, and fiber splitting while promoting muscle fiber growth. Satellite cell density (Pax7+ cells/fiber), embryonic myosin heavy chain expression (eMyHC), and muscle fiber cross sectional area (CSA) were evaluated via immunohistochemistry. Myonuclei (myonuclei/100 mm) were counted on isolated single muscle fibers.

Results

Tamoxifen treatment depleted satellite cells by ?90% and prevented myonuclear accretion with overload in young and mature mice (p?ConclusionsReliance on satellite cells for overload-induced hypertrophy is dependent on maturational age, and global responses to overload differ in young versus mature mice.

SUBMITTER: Murach KA 

PROVIDER: S-EPMC5504676 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature