زهرا رودباری

Background: Red meat is as an important dietary source that provides part of the nutritional requirements such as proteins, minerals, B-complex vitamins and essential fatty acids. Intramuscular fat is located throughout skeletal muscles. It is responsible for the marbling seen in certain cuts of beef. Marbling is a trait of major economic relevance that positively inAuences sensory quality aspects, including Aavor, juiciness and tenderness of meat. Objectives: the objective of this study was to identify cellular signaling pathways regulating muscle marbling in beef cattle using microarray gene expression data. Methods: publicly available preprocessed transcriptomics data (E-GEOD-46411) from a study by Sadkowski et al was used. They measured gene expression in skeletal muscle of well-marbled beef and lean-marbled beef using Agilent microarrays. Pathway analysis was performed with the pathway visualization and analysis tool, PathVisio. Results: The regulation of marbling is possibly the result of interaction of signaling pathways in muscle, fat and intramuscular connective tissue, identifying these processes with pathway analysis can help to decipher the key marbling processes. Pathway analysis revealed 17 pathways that showed differences in expression (z-score > 1.96) between well-marbled and lean marbled beef. MAPK (WP998) and P38 MAPK (WP1037) signaling, two pathways well known two affect lipid metabolism, were enriched in the well marbling breed. In addition, the signaling pathways “hypertrophy modelâ€-, “microRNAs in cardio myocyte hypertrophyâ€- and “physiological and pathological hypertrophy of the heartâ€- that play a role in tissue development were affected. Interestingly, the analyses also demonstrated that pathways related to immune response (IL signaling, TCR signaling and Toll-like receptor signaling pathways) and insulin signaling, mitochondrial gene expression and Vitamin D metabolism were enriched and might act together with the pathways related