GROWTH AND DEVELOPMENT SYMPOSIUM: STEM AND PROGENITOR CELLS IN ANIMAL GROWTH: The regulation of beef quality by resident progenitor cells1

Abstract

The intramuscular adipose tissue deposition in the skeletal muscle of beef cattle is a highly desired trait essential for high-quality beef. In contrast, the excessive accumulation of crosslinked collagen in intramuscular connective tissue contributes to beef toughness. Recent studies revealed that adipose tissue and connective tissue share an embryonic origin in mice and may be derived from a common immediate bipotent precursor in mice and humans. Having the same linkages in the development of adipose tissue and connective tissue in beef, the lineage commitment and differentiation of progenitor cells giving rise to these tissues may directly affect beef quality. It has been shown that these processes are regulated by some key transcription regulators and are subjective to epigenetic modifications such as DNA methylation, histone modifications, and microRNAs. Continued exploration of relevant regulatory pathways is very important for the identification of mechanisms influencing meat quality and the development of proper management strategies for beef quality improvement.

Keywords: adipogenesis; beef quality; connective tissue; fibro/adipogenic progenitors; fibrogenesis; intramuscular adipose tissue.

Figure 1.

FAPs are present in skeletal muscle of cattle. (A) PDGFRα⁺Pax7⁻ FAPs were identified in skeletal muscle of a Brahman heifer by immunohistochemistry using antibodies against PDGFRα (green), Pax7 (red), and laminin (gray). (B) Cells isolated from skeletal muscle of a Brahman heifer were induced for myogenic differentiation as described previously (Fu et al., 2018b). Immunocytochemistry showed that PDGFRα⁺ FAPs (red) failed to differentiate into myosin heavy-chain (MHC) positive myotubes (green). (C) PDGFRα⁺ FAPs were sorted from cells isolated from skeletal muscle of a Brahman heifer as described previously (Huang et al., 2012) and induced for adipogenic differentiation (Fu et al., 2018b). Immunocytochemistry showed that FAPs gave rise to both adipocytes positive for perilipin (red) and fibroblast-like cells positive for vimentin (Vim, green). Nuclei were stained with Dapi (blue). Scale bar = 100 µm.