Transcriptome sequencing analysis of porcine MDM response to FSL-1 stimulation

Transcriptomic Profiling of Skeletal Muscle Reveals Candidate Genes Influencing Muscle Growth and Associated Lipid Composition in Portuguese Local Pig Breeds

Simple Summary

Screening and interpretation of differentially expressed genes and associated biological pathways was conducted among experimental groups with divergent phenotypes providing valuable information about the metabolic events occurring and identification of candidate genes with major regulation roles. This comparative transcriptomic analysis includes the first RNA-seq analysis of the Longissimus lumborum muscle tissue from two Portuguese autochthonous pig breeds with different genetic backgrounds, Alentejano and Bísaro. Moreover, a complementary candidate gene approach was employed to analyse, by real time qPCR, the expression profile of relevant genes involved in lipid metabolism, and therefore with potential impacts on meat composition. This study contributes to explaining the biological basis of phenotypical differences occurring between breeds, particularly the ones related to meat quality traits that affect consumer interest.

Abstract

Gene expression is one of the main factors to influence meat quality by modulating fatty acid metabolism, composition, and deposition rates in muscle tissue. This study aimed to explore the transcriptomics of the Longissimus lumborum muscle in two local pig breeds with distinct genetic background using next-generation sequencing technology and Real-Time qPCR. RNA-seq yielded 49 differentially expressed genes between breeds, 34 overexpressed in the Alentejano (AL) and 15 in the Bísaro (BI) breed. Specific slow type myosin heavy chain components were associated with AL (MYH7) and BI (MYH3) pigs, while an overexpression of MAP3K14 in AL may be associated with their lower loin proportion, induced insulin resistance, and increased inflammatory response via NFkB activation. Overexpression of RUFY1 in AL pigs may explain the higher intramuscular (IMF) content via higher GLUT4 recruitment and consequently higher glucose uptake that can be stored as fat. Several candidate genes for lipid metabolism, excluded in the RNA-seq analysis due to low counts, such as ACLY, ADIPOQ, ELOVL6, LEP and ME1 were identified by qPCR as main gene factors defining the processes that influence meat composition and quality. These results agree with the fatter profile of the AL pig breed and adiponectin resistance can be postulated as responsible for the overexpression of MAP3K14′s coding product NIK, failing to restore insulin sensitivity.

Effect of Pregnane X Receptor on CYP3A29 Expression in Porcine Alveolar Macrophages during Mycoplasma hyopneumoniae Infection

Simple Summary

In the currently intense production process, infection of swine with Mycoplasma pneumonia is common in pig farms around the world, and reduction in the feeding efficiency and the growth rate of sick pigs causes considerable economic losses to the pig-rearing industry. Our study aimed to determine the molecular mechanism by which Mycoplasma hyopneumoniae induces inflammation in pigs. Our study showed that Mycoplasma hyopneumoniae can regulate the expression of CYP3A29 by upregulating PXR during the inflammatory response induced in porcine alveolar macrophages. These findings may provide useful information for breeding pigs that are resistant to disease.

Abstract

Mycoplasma hyopneumoniae (M. hyopneumoniae, Mhp) is the causative agent of mycoplasma pneumonia of swine (MPS). M. hyopneumoniae infection causes inflammation in pigs and leads to considerable economic losses in the pig industry. Pregnane X receptor (PXR) is a pluripotent gene regulatory protein that plays an important role in regulating cytochrome P-450 (CYP) in pigs in the context of inflammatory responses, drug metabolism, homeostasis, etc. We previously reported that cytochrome P450 3A29 (CYP3A29) expression was significantly upregulated in pigs infected with M. hyopneumoniae compared with healthy control pigs. This experiment mainly focused on identifying the role of PXR in the regulation of CYP3A29 and inflammatory factors after M. hyopneumoniae infection by establishing pig alveolar macrophage (PAM) cells in which PXR was overexpressed or silenced. Our results showed that the overexpression of PXR could significantly improve the protein and the mRNA expression levels of CYP3A29 with and without M. hyopneumoniae infection in PAM cells. After the expression of PXR was inhibited, protein and mRNA expression levels of CYP3A29 were significantly reduced with and without M. hyopneumoniae infection in PAM cells. Moreover, PXR can regulate the mRNA expression levels of IL-6 and IL-8 during M. hyopneumoniae infection of PAM cells. In conclusion, these results suggest that PXR positively regulates CYP3A29 expression during the inflammatory response caused by M. hyopneumoniae infection.

Comparative Transcriptomic Analysis of Subcutaneous Adipose Tissue from Local Pig Breeds

When compared to modern lean-type breeds, Portuguese local Alentejano (AL) and Bísaro (BI) pig breeds present a high potential for subcutaneous and intramuscular fat (IMF) deposition which contributes for better meat quality. The aim of this work was to explore the genome function to better understand the underlying physiological mechanisms associated with body fat accretion. Dorsal subcutaneous fat samples were collected at slaughter from adult animals (n = 4 for each breed) with ~150 kg body weight. Total RNA was obtained and sequenced for transcriptome analysis using DESeq2. A total of 458 differentially expressed (DE) genes (q-value < 0.05) were identified, with 263 overexpressed in AL and 195 in BI. Key genes involved in de novo fatty acid biosynthesis, elongation and desaturation were upregulated in AL such as ACLY, FASN, ME1, ELOVL6 and SCD. A functional enrichment analysis of the DE genes was performed using Ingenuity Pathway Analysis. Cholesterol synthesis is suggested to be higher in AL via SREBF2, SCAP and PPARG, while lipolytic activity may be more active in BI through GH and AMPK signalling. Increased signalling of CD40 together with the predicted activation of INSIG1 and INSIG2 in BI suggests that this breed is more sensitive to insulin whereas the AL is less sensitive like the Iberian breed.