MicroRNA-27b Depletion Enhances Endotrophic and Intravascular Lipid Accumulation and Induces Adipocyte Hyperplasia in Zebrafish

Abstract

miR-27b has emerged as a regulatory hub in cholesterol and lipid metabolism, and as a potential therapeutic target for treating atherosclerosis and obesity. However, the impact of miR-27b on lipid levels in vivo remains to be determined. Zebrafish lipids are normally stored as triacylglycerols (TGs) and their main storage sites are visceral, intramuscular, and subcutaneous lipid depots, and not blood vessels and liver. In this study, we applied microRNA-sponge (miR-SP) technology and generated zebrafish expressing transgenic miR-27b-SP (C27bSPs), which disrupted endogenous miR-27b activity and induced intravascular lipid accumulation (hyperlipidemia) and the early onset of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Oil Red O staining predominantly increased in the blood vessels and livers of larvae and juvenile C27bSPs, indicating that miR-27b depletion functionally promoted lipid accumulation. C27bSPs also showed an increased weight gain with larger fat pads, resulting from adipocyte hyperplasia. Molecular analysis revealed that miR-27b depletion increased the expression of genes that are associated with lipogenesis and the endoplasmic reticulum (ER). Moreover, miR-27b-SP increased peroxisome proliferator-activated receptor γ (PPAR-γ), CCAAT enhancer binding protein-α (C/EBP-α, and sterol regulatory element binding transcription factor 1c (SREBP-1c) expression and contributed to lipogenesis and adipogenesis. Conclusion: Our results suggest that miR-27b-SP acts as a lipid enhancer by directly increasing the expression of several lipogenic/adipogenic transcriptional factors, resulting in increased lipogenesis and adipogenesis. In this study, miR-27b expression improved lipid metabolism in C27bSPs, which suggests that miR-27b is an important lipogenic factor in regulating early onset of hyperlipidemia and adipogenesis in zebrafish.

MiRNAs and mRNAs Analysis during Abdominal Preadipocyte Differentiation in Chickens

“…Among the known miRNAs identified, we found that the expression of miRNAs is consistent with the previous results, such as miR-146b, miR-130a, miR-27b-5p, and miR-30a. Studies have shown that overexpression of miR-146b promotes 3T3-L1 cell differentiation [26] and human visceral adipocyte differentiation [27], overexpression miR-130a in porcine preadipocytes can inhibit its differentiation [28], and the depletion of miR-27b promotes lipid accumulation and weight gain in zebrafish [29]. In addition, most abundantly expressed miRNAs, such as miR-30a and miR-106, have been reported that inhibition of miR-30a can promote adipocyte differentiation [30] and miR-106 as negative regulators of adipocyte differentiation [31].…”

Inhibition of miR-27b Regulates Lipid Metabolism in Skeletal Muscle of Obese Rats During Hypoxic Exercise by Increasing PPARγ Expression

“…In order to illustrate the mechanism of the effect of hypoxic exercise on blood lipid, this study observed the changes of miR-27b expression on blood lipids in obese rats with hypoxic exercise. MiR-27b was recently reported to be a key regulator of cholesterol and lipid metabolism ( Hsu et al, 2018 ). In obese people, elevated miR-27 levels in the blood have been associated with higher TG and LDL-C levels and lower HDL-C levels ( Can et al, 2016 ); moreover, it has been suggested that miR-27b can accelerate the development of arteriosclerosis by reducing the expression of PPARγ, thereby inducing perivascular adipose tissue hypertrophy ( Chen et al, 2012 ).…”

“…MiR-27b can bind the 3′UTR of PPARγ mRNA and suppress its expression ( McGregor and Choi, 2011 ). Meanwhile, PPARγ can regulate the expression of a series of lipid metabolism-related genes, including cholesterol 7 alpha-hydroxylase ( CYP7A1 ), fatty acid translocase 36 ( CD36 ), heart-type fatty acid-binding protein ( H-FABP ), fatty acid transport protein ( FATP ), adipose triglyceride lipase ( ATGL ), and lipoprotein lipase ( LPL ) ( Zhu et al, 2015 ; Hsu et al, 2018 ; d’Angelo et al, 2019 ; Xu et al, 2019 ). Interestingly, both hypoxia and exercise have been reported to modulate the expression levels of miR-27b and PPARγ ( Park and Park, 2012 ; Sutliff et al, 2013 ; Tomaz et al, 2016 ).…”

Up-Regulated MicroRNA-27b Promotes Adipocyte Differentiation via Induction of Acyl-CoA Thioesterase 2 Expression

“…It has been reported that miR-27b is down-regulated in in vitro cultured adipocytes and adipose tissue in obesity-related models and that miR-27b impairs adipocyte differentiation in 3T3-L1 cells and human adipose-derived mesenchymal stem cells via its associations with PPARγ and C/EBPα [24][25][26][27]. In zebrafish, depletion of miR-27b has shown increases in PPARγ, C/EBPα, and SREBP-1c, resulting in the enhancement of adipocyte hyperplasia [28]. In addition to these regulators, miR-27b negatively regulates lysyl oxidase and other genes involved in adipocyte differentiation [29].…”