MicroRNA Expression Profiles in the Subcutaneous Adipose Tissues of Morbidly Obese Chinese Women

Abstract

<b><i>Introduction:</i></b> Obesity is a main global health issue and an outstanding cause of morbidity and mortality. Exploring miRNA profiling may help further studies on obesity. <b><i>Methods:</i></b> Three morbidly obese and 5 normal-weight Chinese women were enrolled in the microarray testing group. Abdominal subcutaneous adipose tissue (SAT) samples were excised. Total RNAs including miRNAs were extracted. Affymetrix GeneChip miRNA 4.0 Array was used to compare the expression profiles of miRNAs between the 2 groups. Two algorithms, miRanda and TargetScan, were used to predict target messenger RNAs (mRNAs). Bioinformatics analysis was then done based on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The sample sizes were further expanded to 8 morbidly obese and 9 normal-weight subjects, and quantitative real-time PCR (qRT-PCR) was utilized to verify the expression of differential miRNAs and target genes. <b><i>Results:</i></b> As per the microarray assay, 58 miRNAs were differentially expressed in the SAT from the morbidly obese and normal-weight groups (Fold >4, <i>p</i> < 0.01, FDR <0.05); 54 of these were downregulated and 4 were upregulated in morbidly obese subjects. A total of 1,333 target genes were jointly predicted by miRanda and TargetScan. Further bioinformatics analysis showed that the differential miRNAs were involved in 269 significant biological functions and 89 significant signaling pathways. The validation experiment by qRT-PCR showed that the expression levels of miRNA-143-5p, miRNA-143-3p, miRNA-145-5p, and let-7a-5p were downregulated in morbidly obese subjects, consistent with the microarray detection. High-mobility group A2 (<i>HMGA2</i>), a target gene of the downregulated miRNA let-7a-5p, was first found to be upregulated 3.19-fold in the SAT of morbidly obese Chinese women when compared to normal-weight controls. <b><i>Conclusions:</i></b> MiRNA downregulation is a hallmark of intact SAT in a morbidly obese state. Transcription (DNA-dependent), small-molecule metabolic processes, the MAPK signaling pathway, and cancer-related pathways may play important roles in the occurrence and development of obesity. For the first time, we proved that <i>HMGA2</i>, a target gene of let-7a-5p, is upregulated in the SAT of morbidly obese Chinese women.

microRNAs in Human Adipose Tissue Physiology and Dysfunction

“…HFD causes the hypermethylation of MiR-30 genes via the activation of AMPK and delta-like ligand 4 (DLL4)-Notch signaling, leading to their downregulation and the exacerbation of inflammation and insulin resistance in an animal model of obesity [136]. Human obesity is associated with decreased miR-30a expression in SAT but with elevated serum levels [30,137]. miR-17 (by blocking STAT3 and apoptosis signal-regulating kinase 1-ASK1 expression) can also suppress pro-inflammatory responses [138,139].…”

“…HSL-hormone sensitive lipase; IDH1-isocitrate dehydrogenase 1; IGF2R-insulin-like growth factor 2 receptor; IL-interleukin; LPS-lipopolysaccharide; Mapk14-mitogen-activated protein kinase 14; MEF-mouse embryonic fibroblasts; MEFD2-myocyte enhancer factor 2D; MSC-mesenchymal stem cells; NAFLD-non-alcoholic fatty liver disease; NASH-non-alcoholic steatohepatitis; OSX-osterix; PCOS-polycystic ovary syndrome; PHLPP2-PH domain and leucine-rich repeat protein phosphatase 2; PPARα-peroxisome-proliferator-activated receptor α; PPARγ-peroxisome-proliferator-activated receptor γ; RAI14-retinoic acid-induced protein 14; RUNX2-runt-related transcription factor 2; SAT-subcutaneous adipose tissue; Sertad2-SERTA domain containing 2; SFRP4-secreted frizzled-related protein 4; SIRT1-sirtuin 1; STAT1-signal transducer and activator of transcription 1; STAT3-signal transducer and activator of transcription 3; TCF7L2-T cell-specific transcription factor 7-like 2; TGFβ-transforming growth factor β; TNFα-tumor necrosis factor-alpha; T2DM-type 2 diabetes mellitus; VAT-visceral adipose tissue; Wnt3a-a Wnt ligand. ↑in obesity [8] miR-30b/c Rip140 ↑ adipocyte browning ↑ thermogenesis murine white and brown preadipocytes C57BL/6 mice [97] ↓in obesity [30] miR-129-5p IGF2 EGR1 FABP4 UCP1 PPARγ ↓ adipogenesis ↓adipocyte browning murine primary adipocytes db/db mice [101] ↑in obesity [101] ↓ downregulation; ↑ upregulation; apoE-apolipoprotein E; Bace1-β-secretase 1; BMI-body mass index; Cdo-surface protein Cdo; C/EBPα-CCAAT/enhancer-binding protein α; C/EBPβ-CCAAT/enhancer-binding protein β; Cox7-cytochrome c oxidase subunit 7; Cox8-cytochrome c oxidase subunit 7; db/db mice-mice homozygous for the diabetes spontaneous mutation; Dgcr8-DiGeorge syndrome critical region 8; DIO-diet-induced obesity; EGR1-early growth factor response 1; FABP4-fatty acid binding protein 4; FGF21-fibroblast growth factor 21; HIF1AN-hypoxia inducible factor 1 subunit alpha inhibitor; IGFBP5-insulin-like growth factor binding protein 5; IGF2-insulin growth factor 2; MADS-multipotent adipose-derived stem cells; ob/ob mice-mice homozygous for the obese spontaneous mutation; PDE1B-phosphodiesterase 1B; PGC1α-peroxisome PPARγ coactivator 1 α; PPARα-peroxisome-proliferator-activated receptor α; PPARγ-peroxisome-proliferator-activated receptor γ; PRMD16-PR domain containing 16; Rip140-receptor-interacting protein 140; RUNXT1T-runt-related transcription factor 1 partner transcriptional co-repressor 1; SAT-subcutaneous adipose tissue; SIRT1-sirtuin 1; Tob1-transducer of erbB2 1; VAT-visceral adipose tissue; UCP1-uncoupling protein 1.…”

“…The remodeling of WAT in response to the excess of nutrients is accompanied by changes in the WAT miRNOME, with several miRNAs being up- and downregulated [ 29 ]. Moreover, several adipocyte-selective miRNAs implicated in adipocyte proliferation and differentiation in normal-weight individuals are differentially expressed in adipose tissues of obese subjects [ 8 , 9 , 30 ].…”

“…This takes place in the case of miR-204 and miR-637, which target members of the Wnt/β-catenin signaling pathway: runt-related transcription factor 2 (RUNX2) and osterix (OSX), respectively [ 45 , 46 ]. The increased expression of miR-204 characterizes VAT in human obesity and impairs mitochondrial biogenesis and the development of brown adipose tissue (BAT) in rodents [ 9 , 30 ]. Obesity-related changes in miR-637 expression in human adipose tissue have not been reported to date; however, its serum levels increase during dietary weight loss intervention [ 47 ].…”

“…Consistently, decreased levels of this miRNA accompany human preadipocyte differentiation [ 8 , 38 , 52 ]. However, while the decreased expression of miR-27b was found in the SAT of obese patients with T2DM and VAT, and individuals with non-alcoholic steatohepatitis (NASH), the SAT of metabolically healthy obese individuals was characterized by increased levels of miR-27b, and weight loss did not influence its expression [ 9 , 30 , 37 , 53 ]. In turn, obese patients with polycystic ovary syndrome (PCOS) tended to exhibit decreased serum miR-27b levels [ 54 ].…”