Abstract
MicroRNAs (miRNAs) are non-coding small RNA ∼22 nucleotides in length that can regulate the expression of a wide range of coding genes at the post-transcriptional level. Visceral adipose tissues (VATs) and subcutaneous adipose tissues (SATs), the two main fat compartments in mammals, are anatomically, physiologically, metabolically, and clinically distinct. Various studies of adipose tissues have focused mainly on DNA methylation, and mRNA and protein expression, nonetheless little research sheds directly light on the miRNA transcriptome differences between these two distinct adipose tissue types. Here, we present a comprehensive investigation of miRNA transcriptomes across six variant porcine adipose tissues by small RNA-sequencing. We identified 219 known porcine miRNAs, 97 novel miRNA*s, and 124 miRNAs that are conserved to other mammals. A set of universally abundant miRNAs (i.e., miR-148a-3p, miR-143-3p, miR-27b-3p, miR-let-7a-1-5p, and miR-let-7f-5p) across the distinct adipose tissues was found. This set of miRNAs may play important housekeeping roles that are involved in adipogenesis. Clustering analysis indicated significant variations in miRNA expression between the VATs and SATs, and highlighted the role of the greater omentum in responding to potential metabolic risk because of the observed enrichment in this tissue of the immune- and inflammation-related miRNAs, such as the members of miR-17-92 cluster and miR-181 family. Differential expression of the miRNAs between the VATs and SATs, and miRNA target prediction analysis revealed that the VATs-specific enriched miRNAs were associated mainly with immune and inflammation responses. In summary, the differences of miRNA expression between the VATs and SATs revealed some of their intrinsic differences and indicated that the VATs might be closely associated with increased risk of metabolic disorders.
Highlights
MicroRNAs are a family of small single-stranded non-coding RNAs, which are known to function in a sequencespecific manner to silence specific protein-coding genes at the posttranscriptional level by targeting the 39 untranslated region of mRNAs [1]
We found that distinct Adipose tissues (ATs) from different anatomical locations expressed a core number (284/409, 69.44%) of miRNAs that may fundamental for the regulation of genes involved in adipose metabolism (Table 1), but significant differences in miRNA expression were demonstrated
It is thought that the increase in Visceral adipose tissues (VATs) rather than subcutaneous adipose tissues (SATs) best correlates with measures of insulin resistance [65] and cardiovascular diseases [66], and contributed to the chronic lowgrade inflammation accompanied by these metabolic disorders in ATs [67,68,69]
Summary
MicroRNAs (miRNAs) are a family of small single-stranded non-coding RNAs, which are known to function in a sequencespecific manner to silence specific protein-coding genes at the posttranscriptional level by targeting the 39 untranslated region of mRNAs [1]. MiR-519d [10], miR-335 and miR-377 [11] are strongly associated with lipid metabolism disorders. ATs are deeply involved in the development of metabolic disorders, such as cardiovascular disease and type 2 diabetes mellitus, which are connected to obesity [12,13,14]. Visceral adipose tissues (VATs), which are located within the abdominal and thoracic cavities, have been recognized to be more strongly associated with metabolic risk factors than the subcutaneous adipose tissues (SATs) [15,16,17]. It was suggested that the different impacts that VATs and SATs have on metabolic risk may be because of diverse gene expression profiles that lead to differences in lipolysis and in the production and release of adipokines and cytokines [17]. The results will be of interest for the development of diagnostics and therapeutics for metabolic diseases
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