Abstract
As multipotential stem cells, satellite cells (SCs) have the potential to express adipogenic genes resulting in lipid synthesis with thermal stress. The present study determined the effect of temperature on intracellular lipid synthesis and adipogenic gene expression in SCs isolated from the pectoralis major (p. major) muscle of 7-day-old fast-growing modern commercial (NC) turkeys compared to SCs from unselected slower-growing turkeys [Randombred Control Line 2 (RBC2)]. Since proliferating and differentiating SCs have different responses to thermal stress, three incubation strategies were used: (1) SCs proliferated at the control temperature of 38°C and differentiated at 43° or 33°C; (2) SCs proliferated at 43° or 33°C and differentiated at 38°C; or (3) SCs both proliferated and differentiated at 43°, 38°, or 33°C. During proliferation, lipid accumulation increased at 43°C and decreased at 33°C with the NC line showing greater variation than the RBC2 line. During proliferation at 43°C, peroxisome proliferator-activated receptor-γ (PPARγ) and neuropeptide-Y (NPY) expression was reduced to a greater extent in the NC line than the RBC2 line. At 33°C, expression of PPARγ, NPY, and CCAAT/enhancer-binding protein-β (C/EBPβ) was upregulated, but only in the RBC2 line. During differentiation, both lines showed greater changes in lipid accumulation and in C/EBPβ and NPY expression if the thermal challenge was initiated during proliferation. These data suggest that adipogenic gene expression is more responsive to thermal challenge in proliferating SCs than in differentiating SCs, and that growth-selection has increased temperature sensitivity of SCs, which may significantly affect breast muscle structure and composition.
Highlights
Satellite cells (SCs) are a heterogenous stem cell population (Schultz, 1974; Kuang et al, 2007; Biressi and Rando, 2010; Smith et al, 2013; Tierney and Sacco, 2016), functioning in hypertrophic growth of post-hatch muscle (Moss and Leblond, 1971; Cardiasis and Cooper, 1975)
Myogenic satellite cells (SCs) are partially differentiated stem cells with multiple cellular fates (Asakura et al, 2001; Shefer et al, 2004) that respond to extrinsic stimuli including oxygen concentration (Csete et al, 2001; Redshaw and Loughna, 2012), nutritional status (Powell et al, 2014), and environmental temperature (Harding et al, 2015; Clark et al, 2017) resulting in changes in SC adipogenic characteristics
The present study determined the extent to which selection for higher growth rate and increased breast muscle yield at a processing age has altered the adipogenic potential of cultured 7-day-old p. major muscle satellite cell (pmSC), as well as to identify differential adipogenic gene expression in pmSCs following a hot or cold thermal stress
Summary
Satellite cells (SCs) are a heterogenous stem cell population (Schultz, 1974; Kuang et al, 2007; Biressi and Rando, 2010; Smith et al, 2013; Tierney and Sacco, 2016), functioning in hypertrophic growth of post-hatch muscle (Moss and Leblond, 1971; Cardiasis and Cooper, 1975). Piestun et al (2017) and Patael et al (2019) showed when chickens were challenged with chronic heat stress immediately after hatch for 2 weeks, proliferation of SCs was suppressed while fat deposition was increased in the pectoralis major Major muscle satellite cell (pmSC) proliferation without affecting fat content of the breast muscle (Patael et al, 2019). In vitro studies with cultured pmSCs from both chickens (Harding et al, 2015) and turkeys (Clark et al, 2017) have demonstrated an increased amount of intracellular lipid with heat stress. The increased lipid content was hypothesized to arise from the conversion of pmSCs to an adipogenic-like lineage under the thermal stress
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