Gender and Obesity Specific MicroRNA Expression in Adipose Tissue from Lean and Obese Pigs

Abstract

Obesity is a complex condition that increases the risk of life threatening diseases such as cardiovascular disease and diabetes. Studying the gene regulation of obesity is important for understanding the molecular mechanisms behind the obesity derived diseases and may lead to better intervention and treatment plans. MicroRNAs (miRNAs) are short non-coding RNAs regulating target mRNA by binding to their 3’UTR. They are involved in numerous biological processes and diseases, including obesity. In this study we use a mixed breed pig model designed for obesity studies to investigate differentially expressed miRNAs in subcutaneous adipose tissue by RNA sequencing (RNAseq). Both male and female pigs are included to explore gender differences. The RNAseq study shows that the most highly expressed miRNAs are in accordance with comparable studies in pigs and humans. A total of six miRNAs are differentially expressed in subcutaneous adipose tissue between the lean and obese group of pigs, and in addition gender specific significant differential expression is observed for a number of miRNAs. The differentially expressed miRNAs have been verified using qPCR. The results of these studies in general confirm the trends found by RNAseq. Mir-9 and mir-124a are significantly differentially expressed with large fold changes in subcutaneous adipose tissue between lean and obese pigs. Mir-9 is more highly expressed in the obese pigs with a fold change of 10 and a p-value < 0.001. Mir-124a is more highly expressed in the obese pigs with a fold change of 114 and a p-value < 0.001. In addition, mir-124a is significantly higher expressed in abdominal adipose tissue in male pigs with a fold change of 119 and a p-value < 0.05. Both miRNAs are also significantly higher expressed in the liver of obese male pigs where mir-124a has a fold change of 12 and mir-9 has a fold change of 1.6, both with p-values < 0.05.

miRNA and mRNA expression analysis reveals potential sex-biased miRNA expression

“…Similar studies for miRNA expression have also been reported in male and female samples474849, and relationships of miRNA expression and sex differences have attracted the attention of researchers. Herein, for the specific disease, the two groups with gender-difference, LUAD-male and LUAD-female groups, showed inconsistent miRNA and mRNA expression patterns and fewer common RNAs (Figs 1, 2, 3 and S1).…”

Joint Profiling of miRNAs and mRNAs Reveals miRNA Mediated Gene Regulation in the Göttingen Minipig Obesity Model

“…This research emphasizes the value of a porcine model for human obesity. Moreover, in our previous research we have shown that miRNAs are differentially expressed in lean versus obese pigs from the same pig population, confirming their relevance in obesity studies [10]. One challenge with working with the pig as a model for miRNA studies is the issue of miRNA target finding.…”

“…In total, 40 protein-coding genes and 18 miRNAs were significantly differentially expressed with fold changes larger than 1.5 suggesting important differences in obesity-relevant gene expression between lean and obese Göttingen minipigs. We expected to encounter a large number of differentially expressed protein-coding genes and miRNAs in this study, since the genes included were individually selected, based on results from previous obesity studies in pigs and other organisms as well as unpublished information obtained from conferences [9,10,18–20]. Previous studies using the same animals have shown significant differential expression of several other inflammation (mainly genes involved in innate immunity) and obesity relevant genes in multiple tissues as well as a slight enlargement of the adipocytes within the obese minipigs [20,22].…”

“…MiR-30a and miR-148 are both involved in adipocyte differentiation, downregulated in obese adipose tissue in mice and are involved in myogenic differentiation [37–39]. In contrast, MiR-9-5p is upregulated in serum of human diabetic patients and, in another study, upregulated in porcine adipose tissue from a mixed breed population [10,40]. LEP also has a target site for miR-125a, which is downregulated in obese adipose tissue, an observation in agreement with human studies [41].…”

“…The genes included in this study were individually selected based on results from previous obesity studies in pigs and other organisms as well as unpublished information obtained from conferences [9,10,18–20]. Primer sequences for protein coding gene expression were designed using the Primer3 software (http://bioinfo.ut.ee/primer3/).…”