Gene expression patterns during intramuscular fat development in cattle1

Abstract

Deposition of intramuscular fat, or "marbling," in beef cattle contributes significantly to meat quality variables, including juiciness, flavor, and tenderness. The accumulation of intramuscular fat is largely influenced by the genetic background of cattle, as well as their age and nutrition. To identify genes that can be used as early biomarkers for the prediction of marbling capacity, we studied the muscle transcriptome of 2 cattle crossbreeds with contrasting intramuscular fat content. The transcriptomes of marbling LM tissue of heifers from Wagyu x Hereford (WxH; n = 6) and Piedmontese x Hereford (PxH; n = 7) crosses were profiled by using a combination of complementary DNA microarray and quantitative reverse transcription-PCR. Five biopsies of LM were taken from each animal at approximately 3, 7, 12, 20, and 25 mo from birth. Tissue was also collected from the LM of each animal at slaughter (approximately 30 mo). Microarray experiments, conducted on the first 3 biopsies of 2 animals from each crossbreed, identified 97 differentially expressed genes. The gene expression results indicated that the LM transcriptome of animals with high marbling potential (WxH) could be reliably distinguished from less marbled animals (PxH) when the animals were as young as 7 mo of age. At this early age, one cannot reliably determine meaningful differences in intramuscular fat deposition. We observed greater expression of a set of adipogenesis- and lipogenesis-related genes in the LM of young WxH animals compared with their PxH contemporaries. In contrast, genes highly expressed in PxH animals were associated with mitochondrial oxidative activity. Further quantitative reverse transcription-PCR experiments revealed that the messenger RNA of 6 of the lipogenesis-related genes also peaked at the age of 20 to 25 mo in WxH animals. The messenger RNA expression of ADIPOQ, SCD, and THRSP was highly correlated with intramuscular fat content of an individual in WxH animals. Our study provides clear evidence of early molecular changes associated with marbling and also identifies specific time frames when intramuscular fat development in cattle muscle can be detected by using gene expression. This information could be used by animal scientists to design optimal nutrition for high marbling potential. In addition, the genes found to be highly expressed during development of marbling could be used to develop genetic markers or biomarkers to assist with beef production strategies.

Longitudinal muscle gene expression patterns associated with differential intramuscular fat in cattle

“…THRSP was ranked in first position illustrating that it met this criterion the best. From this perspective, one could conclude that THRSP is the most robust of the end-point characterisers of current marbling status in contrasting these two breeds, in line with a previous publication based on a cDNA array (Wang et al, 2009). However, further exploration of these profiles, including THRSP, showed they did not increase monotonically at each postnatal time point and also that the profiles converged during feedlotting, just before slaughter, when the difference in the marbling phenotype is at its most apparent (Figure 2a).…”

“…Similarly, there are no known causal mutations, the contributing cell populations have not been well defined Bonnet et al, 2010), and gene expression analyses have tended to document increases in the expression of end-point fatty acid metabolism proteins such as members of the fatty acid-binding protein family (Wang et al, 2009;De Jager et al, 2013). However, genetics is a strong driver of marbling, such that in elite Wagyu animals IMF can exceed 50% in skeletal muscle (Gotoh et al, 2009), whereas in other breeds such as Brahman the figure averages <5%.…”

“…High throughput gene expression analysis has previously been used to contrast these two breeds in the context of differential fat development (Wang et al, 2009). However, the previous publication (Wang et al, 2009) was based on a far less comprehensive cDNA array.…”

“…However, the previous publication (Wang et al, 2009) was based on a far less comprehensive cDNA array. Highlighted genes included THRSP and FABP4.…”

Intramuscular fat content in meat-producing animals: development, genetic and nutritional control, and identification of putative markers

“…Transcriptomic studies were also performed during muscle growth in a time when animals had none visible differences in IMF level. One study comparing different genotypes of cattle from 3 to 25 months of age indicated that adipogenesis-and lipogenesisrelated genes (such as FABP4 again, AdipQ, and c/EBPbeta) were more expressed at 7 months of age in muscles of genotypes with a potential higher propensity to deposit IMF (Wang et al, 2009a). This is a great importance because the adequate timing to reveal early markers of IMF content remains elusive in much species.…”