Introduction: The aim of this is study was to analyse the expression of miR-193b, miR-378, miR-Let7-d, and miR-222 in human visceral adipose tissue (VAT), as well as their association with obesity, insulin resistance (IR), and their role in the regulation of genes controlling adipose tissue homeostasis, including adipocytokines, the phosphatase and tension homologue (PTEN), and tumour protein 53 (p53).
Material and methods: VAT was obtained from normal-weight (NW), overweight, and obese (OW/OB) subjects with and without IR. Stem-loop RT-qPCR was used to evaluate miRNA expression levels. miRTarBase 4.0, miRWalk, and DIANA-TarBase v8 were used for prediction of validated target gene of the miRNA analysed. A qPCR was used to evaluate PTEN, p53, leptin (LEP), and adiponectin (ADIPOQ) mRNA.
Results: miR-222 was lower in IR subjects, and miR-222 and miR-378 negatively correlated with HOMA-IR. PTEN and p53 are miR-222 direct targets according to databases. mRNA expression of PTEN and p53 was lower in OW/OB subjects with and without IR, compared to NW group and its levels positively associated with miR-222. Additionally, p53 and PTEN are positively associated with serum leptin levels. On the other hand, miR-193b and miR-378 negatively correlated with serum leptin but not with mRNA levels. Moreover, miR-Let-7d negatively correlated with serum adiponectin but not with adiponectin mRNA levels.
Conclusions: Lower miR-222 levels are associated with IR, and PTEN and p53 expression; the implication of these genes in adipose tissue homeostasis needs more research.
Keywords: adipocytokines; insulin resistance; microRNA (miRNA); obesity; visceral adipose tissue.