Increased intramuscular fat induced by reduced dietary protein in finishing pigs: effects on the longissimus lumborum muscle proteome.
Due to genetic selection towards reduced subcutaneous fat, the amount of intramuscular fat (IMF) in commercial pigs has been reduced (<2.5%), compromising pork quality. The use of reduced protein diets (RPD) is a good strategy to increase IMF in pigs. We have previously shown that increased IMF promoted by RPD is mediated by lysine restriction. However, the molecular mechanisms involved remain unclear. Here we performed a proteomics study to quantify differentially regulated proteins in the longissimus lumborum muscle of pigs (n = 4) fed a normal protein diet (NPD) (16.0% CP) or a reduced protein diet (RPD) (13.0% CP). Both isobaric tags for relative and absolute quantification (iTRAQ) and label-free methods were used. Glycolysis, Krebs cycle, mitochondrion, contractile proteins, respiratory chain, and calcium signalling were significantly enriched in muscle samples. Thirty five proteins shown to be differentially expressed and were classified using gene ontology (GO) terms and functional annotation clustering, highlighting main relevant biological networks and proteins associated with muscle physiology and meat quality. Members of GO categories "muscle contraction" and "structural constituents of cytoskeleton", were the most significantly up-regulated proteins in muscle from pigs fed RPD. Conversely, in animals fed NPD most up-regulated proteins were enzymes involved in the regulation of energy metabolism. Our data revealed that RPD affects the amounts of proteins related to fibre type and structure, and energy metabolism. It is suggested that the increased IMF promoted by dietary protein reduction in growing-finishing pigs is mediated by shifting the metabolic properties of fibres from glycolytic to oxidative.
CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, Alto da Ajuda, 1300-477 Lisbon, Portugal. Adealmeida@rossvet.edu.kn.
V M R
VM
Pires
CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, Alto da Ajuda, 1300-477 Lisbon, Portugal. Adealmeida@rossvet.edu.kn.
M S
MS
Madeira
Centre of Excellence in Mass Spectrometry, University of York, York, YO10 5DD, UK.
A A
AA
Dowle
Centre of Excellence in Mass Spectrometry, University of York, York, YO10 5DD, UK.
J
J
Thomas
CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, Alto da Ajuda, 1300-477 Lisbon, Portugal. Adealmeida@rossvet.edu.kn.
A M
AM
Almeida
CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, Alto da Ajuda, 1300-477 Lisbon, Portugal. Adealmeida@rossvet.edu.kn.
J A M
JA
Prates
D000821:Animal Feed; D000818:Animals; D015415:Biomarkers; D004044:Dietary Proteins; D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism; D005504:Food Analysis; D063427:Food Quality; D008460:Meat / Q000032:analysis / Q000592:standards; D018482:Muscle, Skeletal / Q000737:chemistry* / Q000378:metabolism; D025941:Protein Interaction Mapping; D060066:Protein Interaction Maps; D020543:Proteome; D040901:Proteomics / Q000379:methods; D019655:Quantitative Trait, Heritable; D013552:Swine
D015415:Biomarkers; D004044:Dietary Proteins; D005227:Fatty Acids; D020543:Proteome