Fetal muscle development, mesenchymal multipotent cell differentiation, and associated signaling pathways1,2

Abstract

Meat animals are raised for their carcasses, and carcasses are composed from muscle, fat and bone. Enhancing muscle growth and reducing fat accumulation improve the efficiency of animal production. Fetal stage is crucial for skeletal muscle development. Due to extensive efforts to increase lean growth, marbling (intramuscular fat) is reducing in beef, pork and chicken breast, which impairs the eating quality of meat. Because fat is the major contributor to meat flavor, the presence of intramuscular fat is indispensible for the high eating quality of meat. However, up to now, our understanding of adipogenesis (formation of fat cells) in skeletal muscle is limited. Adipocyte differentiation in skeletal muscle initiates from mesenchymal multipotent cells, which are abundant in skeletal muscle at early developmental stages. In this review, the known cellular mechanisms regulating adipogenesis from multipotent cells are summarized, which include hedgehog, Wingless and Int (Wnt)/α-catenin, and bone morphogenesis protein (BMP) mediated signaling pathways, as well as AMP-activated protein kinase. Promoting adipogenesis inside skeletal muscle will dramatically increase intramuscular fat, improving the quality of meat.

Intermuscular and intramuscular adipose tissues: Bad vs. good adipose tissues

“…41,42 Wnt signaling plays a crucial role in activating myogenic differentiation, while inhibiting adipogenic differentiation. 43,44 Recently, it has been shown that brown adipocytes through involvement of PRDM16 (PR-domain-containing 16) transcription factor are derived from Myf5 positive cells which are also precursors for myogenic cells. 45,46 Bone morphogenetic protein 7 (BMP7) promotes brown adipogenesis through promoting PRDM16 expression in mice.…”

Moderately increased maternal dietary energy intake delays foetal skeletal muscle differentiation and maturity in pigs

“…Muscle fibre number is known to be an important determinant of muscle mass [17]. In mammals, muscle fibres are formed prenatally, and subsequent skeletal muscle development depends largely on muscle fibre hypertrophy [18,19]. Therefore, foetal stage is crucial for skeletal muscle development and could potentially permanently influence postnatal skeletal muscle growth processes of the offspring, thereby producing long-lasting physiological effects.…”

Late gestation supplementation of beef cows differing in body condition score: Effects on cow and calf performance1,2

“…Prior research has shown that nutrient restriction during early to mid-gestation negatively affects fetal growth (Wu et al, 2004), including myogenesis and adipogensis (Du et al, , 2011, decreases tenderness and adipose tissue deposition , decreases the responsiveness of the hypothalamic-pituitary-adrenal axis in female progeny (Long et al, 2010a), organ development and function (Long et al, 2009), and gene expression (Long et al, 2010b). Nevertheless, even though differences in organ cellular composition and function were noted, Long et al (2009Long et al ( , 2010b showed that when beef cows are provided nutrients at a level that meets nutritional requirements during late gestation, it can ameliorate many of the negative consequences (growth and carcass characteristics) of intrauterine growth restriction resulting from early-to midgestational nutrient restriction.…”