miR-128 promoted adipogenic differentiation and inhibited osteogenic differentiation of human mesenchymal stem cells by suppression of VEGF pathway

Circ_0006873 suppresses the osteogenic differentiation of human-derived mesenchymal stem cells through mediating miR-20a/SMURF2 axis in vitro

The clinical application of human-derived mesenchymal stem cells (hMSCs) in osteoporosis (OP) treatment is promising. We aimed to uncover the role of circular RNA 0006873 (circ_0006873) in OP progression using hMSCs. The levels of circ_0006873, pantothenate kinase 2 (PANK2) messenger RNA (mRNA), microRNA-20a (miR-20a), SMAD specific E3 ubiquitin protein ligase 2 (SMURF2) mRNA and the mRNA levels of osteogenesis-related markers were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of osteogenesis-related markers and SMURF2 was detected by Western blot assay. Alkaline phosphatase (ALP) staining and activity were determined using an ALP staining Kit and an ALP Colorimetric Assay Kit. Circ_0006873 was highly expressed in the serum samples and bone tissue samples of OP patients compared with control cases. Circ_0006873 overexpression down-regulated the expression of osteogenesis-related markers and reduced ALP staining and activity. Circ_0006873 down-regulated miR-20a level through its interaction with miR-20a in hMSCs. Circ_0006873 suppressed osteogenic differentiation through targeting miR-20a. SMURF2 was a molecular target of miR-20a, and miR-20a promoted osteogenic differentiation through targeting SMURF2. Circ_0006873 suppressed the osteogenic differentiation of hMSCs by upregulating SMURF2 level via sponging miR-20a in vitro.

Mechanism of vascular endothelial cell-derived exosomes modified with vascular endothelial growth factor in steroid-induced femoral head necrosis

Steroid-induced avascular necrosis of the femoral head (SANFH) is an intractable orthopedic disease. This study investigated the regulatory effect and molecular mechanism of vascular endothelial cell (VEC)-derived exosomes (Exos) modified with vascular endothelial growth factor (VEGF) in osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in SANFH. VECs were culturedin vitroand transfected with adenovirus Adv-VEGF plasmids. Exos were extracted and identified.In vitro/vivoSANFH models were established and treated with VEGF-modified VEC-Exos (VEGF-VEC-Exos). The internalization of Exos by BMSCs, proliferation and osteogenic and adipogenic differentiation of BMSCs were determined by the uptake test, cell counting kit-8 (CCK-8) assay, alizarin red staining, and oil red O staining. Meanwhile, the mRNA level of VEGF, the appearance of the femoral head, and histological analysis were assessed by reverse transcription quantitative polymerase chain reaction and hematoxylin-eosin staining. Moreover, the protein levels of VEGF, osteogenic markers, adipogenic markers, and mitogen-activated protein kinase (MAPK)/extracellular regulated protein kinases (ERK) pathway-related indicators were examined by Western blotting, along with evaluation of the VEGF levels in femur tissues by immunohistochemistry. Glucocorticoid (GC) induced adipogenic differentiation of BMSCs and inhibited osteogenic differentiation. VEGF-VEC-Exos accelerated the osteogenic differentiation of GC-induced BMSCs and inhibited adipogenic differentiation. VEGF-VEC-Exos activated the MAPK/ERK pathway in GC-induced BMSCs. VEGF-VEC-Exos promoted osteoblast differentiation and suppressed adipogenic differentiation of BMSCs by activating the MAPK/ERK pathway. VEGF-VEC-Exos accelerated bone formation and restrained adipogenesis in SANFH rats. VEGF-VEC-Exos carried VEGF into BMSCs and motivated the MAPK/ERK pathway, thereby promoting osteoblast differentiation of BMSCs in SANFH, inhibiting adipogenic differentiation, and alleviating SANFH.

VEGF promotes tendon regeneration of aged rats by inhibiting adipogenic differentiation of tendon stem/progenitor cells and promoting vascularization

Studies have shown that the stem cell microenvironment is a key factor for stem cell maintenance or differentiation. In this study, we compared the expression of 23 cytokines such as IL-6, IL-10, and TNFα between young and aged rats during patellar tendon repair by cytokine microarray, and found that significant difference between IL-10, G-CSF, and VEGF at 3, 7, or 14 days post-operatively. The effects of these factors on adipogenic differentiation of TPSCs were examined through western blot and oil red O experiments. It was shown that VEGF had an inhibitive effect on the adipogenic differentiation of TPSCs. SPP-1 was figured out as our target by RNA sequencing and confirmed by western blot in vitro. Further in vivo studies showed that adipocyte accumulation was also decreased in the tendons of aged rats after injection of VEGF and the histological score and biomechanical property were also improved via targeting SPP-1. Furthermore, histochemical results showed that vascularization of the injury sites was significantly elevated. In conclusion, VEGF not only plays an important role in decreasing adipocyte accumulation but also improves vascularization of the tendon during aged tendon healing. We believe active regulation of VEGF may improve the treatment of age-related tendon diseases and tendon injuries.

MicroRNA-149 suppresses osteogenic differentiation of mesenchymal stem cells via inhibition of AKT1-dependent Twist1 phosphorylation

Osteogenic differentiation is a vital process for growth, repair, and remodeling of bones. Accumulating evidence have suggested that microRNAs (miRNAs or miRs) play a crucial role in osteogenic differentiation of mesenchymal stem cells (MSCs). Hence, the current study set out to elucidate the role of miR-149 in osteogenic differentiation of MSCs and the underlying mechanism. First, rat models of bone differentiation were established using the Masquelet-induced membrane technique, and MSCs were isolated. The expression of miR-149 and AKT1 in the rats and cells was detected with RT-qPCR and western blot analysis. The relationships among miR-149, AKT1, and Twist1 were further predicted by online bioinformatics prediction and verified using dual luciferase reporter gene assay. Alteration of miR-149, AKT1, or Twist1 was performed to further explore their effect on osteogenic differentiation of MSCs. miR-149 was poorly expressed in the process of osteogenic differentiation of MSCs, while AKT1 was highly expressed. miR-149 negatively regulated the expression of AKT1, which in turn diminished the protein levels of Twist1 and promoted the phosphorylation levels of Twist1. Lastly, miR-149 acted as an inhibitor of osteogenic differentiation of MSCs, which could be reversed by AKT1. To sum up, miR-149 silencing promoted osteogenic differentiation of MSCs by enhancing Twist1 degradation through AKT1 upregulation, representing a new method for bone repair treatment.

Recent Update on the Molecular Mechanisms of Gonadal Steroids Action in Adipose Tissue

The gonadal steroids, including androgens, estrogens and progestogens, are involved in the control of body fat distribution in humans. Nevertheless, not only the size and localization of the fat depots depend on the sex steroids levels, but they can also highly affect the functioning of adipose tissue. Namely, the gonadocorticoids can directly influence insulin signaling, lipid metabolism, fatty acid uptake and adipokine production. They may also alter energy balance and glucose homeostasis in adipocytes in an indirect way, e.g., by changing the expression level of aquaglyceroporins. This work presents the recent advances in understanding the molecular mechanism of how the gonadal steroids influence the functioning of adipose tissue leading to a set of detrimental metabolic consequences. Special attention is given here to highlighting the sexual dimorphism of adipocyte functioning in terms of health and disease. Particularly, we discuss the molecular background of metabolic disturbances occurring in consequence of hormonal imbalance which is characteristic of some common endocrinopathies such as the polycystic ovary syndrome. From this perspective, we highlight the potential drug targets and the active substances which can be used in personalized sex-specific management of metabolic diseases, in accord with the patient's hormonal status.

MicroRNA in cardio-metabolic disorders

Hyperlipidemia is correlated with several health problems that contain the combination of hypertension, obesity, and diabetes mellitus, which are grouped as metabolic syndrome. Though the lipid-lowering agents, such as statins, which aims to reduce serum low-density lipoprotein cholesterol (LDL-C) has been considered as one of the most effective therapeutics in treating hyperlipidemia and coronary artery diseases, the persistent high risk of atherosclerosis after intensive lipid-lowering therapy could not be simply explained by hyperlipidemia. Therefore, it is necessary to identify novel factors to manage treatment and to predict risk of cardio-metabolic events. Endeavor over the past several decades has demonstrated the important functions of microRNAs in modulating macrophage activation, lipid metabolism, and hyperlipidemia. In the present review, we summarized the recent findings which highlighted the contributions of microRNAs in regulating serum lipid metabolism. Furthermore, we also provided the potential mechanisms whereby microRNAs controlled lipid metabolism and the risk of cardio-metabolic disorders, which could help us to identify microRNAs as a promising therapeutic target for hyperlipidemia and its related cardiovascular diseases.

The miR-187 induced bone reconstruction and healing in a mouse model of osteoporosis, and accelerated osteoblastic differentiation of human multipotent stromal cells by targeting BARX2

BACKGROUND

Multiple microRNAs (miRNAs) have been proven to regulate osteogenic differentiation by affecting the Runx2 signaling pathway. The intervention of miRNA can delay the progress of osteoporosis (OP) and induce fracture repair by affecting bone regeneration. However, the function and mechanism of miR-187 in osteoporotic fractures are still unknown.

METHODS

We first established the OP mouse model. Next, the BMD value was certified by iDXA. The miR-187 level in the OP mice and serum of OP patients was identified through qRT-PCR. Bone repair and bone healing were assessed through toluidine blue staining and X-ray, and BARX2 expression was also confirmed. Osteogenesis-related proteins, ALP activity, and the matrix mineralization state were evaluated by western blot, ALP staining, and Alizarin Red staining in hMSCs after transfection with miR-187 mimics, miR-187 inhibitor, or human BarH-like homeobox 2 (BARX2) siRNA. Moreover, the interplay between miR-187 and BARX2 was identified through the dual-luciferase reporter.

RESULTS

The BMD value was notably reduced in the OP mice, and miR-187 was markedly downregulated in the OP mice and serum of OP patients. Meanwhile, we proved that miR-187 induced bone reconstruction and healing, and downregulated BARX2 in the OP mouse model. We also proved that BARX2 was a direct target of miR-187, and could be significantly downregulated by miR-187. Furthermore, miR-187 induced osteogenic differentiation of hMSCs by targeting BARX2.

CONCLUSIONS

The miR-187 might have a significant therapeutic effect in osteoporotic fractures. miR-187 accelerated osteogenic differentiation of hMSCs by directly regulating BARX2.

The emerging role of miR-128 in musculoskeletal diseases

MicroRNA-128 (miR-128) is associated with cell proliferation, differentiation, migration, apoptosis, and survival. Genetic analysis studies have demonstrated that miR-128 participates in bone metabolism, which involves bone marrow-derived mesenchymal stem cells, osteoblasts, osteoclasts, and adipocytes. miR-128 also participates in regeneration of skeletal muscles by targeting myoblast-associated proteins. The deregulation of miR-128 could lead to a series of musculoskeletal diseases. In this review, we discuss recent findings of miR-128 in relation to bone metabolism and muscle regeneration to determine its potential therapeutic effects in musculoskeletal diseases, and to propose directions for future research in this significant field.

Mechanisms of miR‑128‑3p in inhibiting osteoblast differentiation from bone marrow‑derived mesenchymal stromal cells

The authors' previous study demonstrated that miR-128 may exert an inhibitory effect on the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BM-MSCs), but its downstream mechanisms remain to be elucidated. The aim of the present study was to investigate the microRNA (miRNA/miR) and mRNA profiles of differentiated and undifferentiated BM-MSCs and explore new downstream targets for miR-128. The sequencing datasets of GSE107279 (miRNA) and GSE112318 (mRNA) were downloaded from the Gene Expression Omnibus database. The differentially expressed miRNAs (DEMs) and genes (DEGs) were identified using the DESeq2 method. The target genes of DEMs were predicted by the miRwalk 2.0 database. The hub target genes of miR-128 were screened by constructing the protein-protein interaction (PPI) network and module analysis. The expression levels of miR-128 and crucial target genes were validated by reverse transcription-quantitative (RT-q) PCR before or after transfection of miR-128 mimics to BM-MSCs. The miRNA expression profile analysis identified miR-128 as one of the significantly downregulated DEMs (total 338) in differentiated BM-MSCs compared with the undifferentiated control. A total of 103 predicted target genes of miR-128-3p were overlapped with upregulated DEGs. By calculating the topological properties of each protein in the PPI network, 6 upregulated genes (KIT, NTRK2, YWHAB, GAB1, AXIN1 and RUNX1; fold change was the highest for NTRK2) were considered to be hub genes. Of these, 4 were enriched in module 4 (RUNX1, KIT, GAB1 and AXIN1; RUNX1 was particularly crucial as it can interact with the others), while one was enriched in module 7 (YWHAB). The expression levels of miR-128 and these 6 target genes during the osteogenic differentiation were experimentally confirmed by RT-qPCR. In addition, the expression levels of these 6 genes were significantly reversed after transfection of miR-128-3p mimics into rat BM-MSCs compared with the miR-control group. These findings indicated that miR-128-3p may inhibit the osteoblast differentiation of BM-MSCs by downregulation of these 6 genes, particularly RUNX1, YWHAB and NTRK2.

Identification of potential specific biomarkers and key signaling pathways between osteogenic and adipogenic differentiation of hBMSCs for osteoporosis therapy

Background

The differentiation of bone mesenchymal stem cells (BMSCs) into adipogenesis (AD) rather than osteogenesis (OS) is an important pathological feature of osteoporosis. Illuminating the detailed mechanisms of the differentiation of BMSCs into OS and AD would contribute to the interpretation of osteoporosis pathology.

Methods

To identify the regulated mechanism in lineage commitment of the BMSCs into OS and AD in the early stages, the gene expression profiles with temporal series were downloaded to reveal the distinct fates when BMSCs adopt a committed lineage. For both OS and AD lineages, the profiles of days 2–4 were compared with day 0 to screen the differentially expressed genes (DEGs), respectively. Next, the functional enrichment analysis was utilized to find out the biological function, and protein-protein interaction network to predict the central genes. Finally, experiments were performed to verify our finding.

Results

FoxO signaling pathway with central genes like FoxO3, IL6, and CAT is the crucial mechanism of OS, while Rap1 signaling pathway of VEGFA and FGF2 enrichment is more significant for AD. Besides, PI3K-Akt signaling pathway might serve as the latent mechanism about the initiation of differentiation of BMSCs into multiple lineages.

Conclusion

Above hub genes and early-responder signaling pathways control osteogenic and adipogenic fates of BMSCs, which maybe mechanistic models clarifying the changes of bone metabolism in the clinical progress of osteoporosis. The findings provide a crucial reference for the prevention and therapy of osteoporosis.

miR-128 regulated the proliferation and autophagy in porcine adipose-derived stem cells through targeting the JNK signaling pathway

PURPOSE

microRNA-128 (miR-128), a brain-enriched microRNA, has been reported to play a crucial role in the treatment of diseases. The c-Jun N-terminal kinase (JNK) signaling pathway exerts various biological functions such as regulation of cell proliferation, differentiation and apoptosis. In this study, we investigated the role of the miRNA-128-JNK signaling pathway in proliferation, apoptosis and autophagy of porcine adipose-derived stem cells (ASCs).

METHODS

After over-expressing miR-128 in porcine ASCs, cell proliferation was determined by 2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide (XTT) method, cell apoptosis was observed by Flow cytometry (FCM), the expression of miR-128, B-cell lymphoma 2 (Bcl-2), and Bcl-2-associated X protein (Bax) was measured by RNA preparation and reverse transcription polymerase chain reaction (RT-PCR), and protein expression of JNK, phosphorylated JNK (p-JNK) and LC3B was analyzed by Western Blot analysis.

RESULTS

The over-expression of miR-128 potently promoted cell proliferation and autophagy while suppressed the apoptosis of porcine ASCs. In addition, the down-regulated expression level of p-JNK was detected in miR-128-over-expressed porcine ASCs. However, followed by the block of the JNK signaling pathway using SP600125 inhibitor, the effects of miR-128 on the proliferation, apoptosis and autophagy of porcine ASCs were significantly suppressed.

CONCLUSION

It is demonstrated that the miR-128-JNK signaling pathway is a potential therapeutic target for the treatment of obesity.

miR-128 plays a critical role in murine osteoclastogenesis and estrogen deficiency-induced bone loss

Postmenopausal osteoporosis (PMOP) is a severe health issue faced by postmenopausal women. microRNA-128 (miR-128) is associated with aging, inflammatory signaling, and inflammatory diseases, such as PMOP. It has also been reported to modulate in vitro osteogenic/adipogenic differentiation. However, its function in osteoclast formation is unknown.

Methods: First, the expression of miR-128 and nuclear factor of activated T cells 1 (Nfatc1, bone resorption master marker) was investigated in bone tissues derived from PMOP patients, while their correlation to each other was also investigated. The levels of miR-128 and Nfatc1 in bone specimens and bone marrow-derived macrophages (BMMs) from mice subjected to ovariectomy (OVX) were also assayed. Next, we employed mice BMMs modified for overexpression and inhibition of miR-128 levels to determine its effect on osteoclast differentiation. Moreover, we generated osteoclastic miR-128 conditional knockout (miR-128^Oc-/-) mice and isolated miR-128 deletion-BMMs to observe its biological function on bone phenotype and osteoclastogenesis in vivo, respectively. The miR-128^Oc-/- BMMs were used to explore the downstream regulatory mechanisms using pull-down, luciferase reporter, and western-blotting assays. Finally, the impact of miR-128 deficiency on OVX-induced bone loss in mice was evaluated.

Results: The miR-128 level was found to be positively correlated with the increase in Nfatc1 level in mouse/human bone specimens and mouse primary BMMs. In vitro experiments demonstrated miR-128 levels that were dependent on activity of osteoclast differentiation and miR-128 overexpression or inhibition in BMMs significantly increased or decreased osteoclastogenesis, respectively. In vivo, we revealed that osteoclastic miR-128 deletion remarkedly increased bone mass through the inhibition of osteoclastogenesis. Mechanistically, we identified sirtuin 1 (SIRT1) as the direct target of miR-128 at the post-transcriptional level during osteoclast differentiation. Increased levels of SIRT1 reduced nuclear factor κB (NF-κB) activity by decreasing the level of acetylation of Lysine 310, as well as inhibiting tumor necrosis factor-α (Tnf-α) and interleukin 1 (IL-1) expressions. Lastly, osteoclastic deletion of miR-128 significantly suppressed OVX-triggered osteoclastogenesis and exerted a protective effect against bone loss in mice.

Conclusions: Our findings reveal a critical mechanism for osteoclastogenesis that is mediated by the miR-128/SIRT1/NF-κB signaling axis, highlighting a possible avenue for the further exploration of diagnostic and therapeutic target molecules in PMOP.

Emergence of MicroRNAs as Key Players in Cancer Cell Metabolism

BACKGROUND

Metabolic reprogramming is a hallmark of cancer. MicroRNAs (miRNAs) have been found to regulate cancer metabolism by regulating genes involved in metabolic pathways. Understanding this layer of complexity could lead to the development of novel therapeutic approaches.

CONTENT

miRNAs are noncoding RNAs that have been implicated as master regulators of gene expression. Studies have revealed the role of miRNAs in the metabolic reprogramming of tumor cells, with several miRNAs both positively and negatively regulating multiple metabolic genes. The tricarboxylic acid (TCA) cycle, aerobic glycolysis, de novo fatty acid synthesis, and altered autophagy allow tumor cells to survive under adverse conditions. In addition, major signaling molecules, hypoxia-inducible factor, phosphatidylinositol-3 kinase/protein kinase B/mammalian target of rapamycin/phosphatase and tensin homolog, and insulin signaling pathways facilitate metabolic adaptation in tumor cells and are all regulated by miRNAs. Accumulating evidence suggests that miRNA mimics or inhibitors could be used to modulate the activity of miRNAs that drive tumor progression via altering their metabolism. Currently, several clinical trials investigating the role of miRNA-based therapy for cancer have been launched that may lead to novel therapeutic interventions in the future.

SUMMARY

In this review, we summarize cancer-related metabolic pathways, including glycolysis, TCA cycle, pentose phosphate pathway, fatty acid metabolism, amino acid metabolism, and other metabolism-related oncogenic signaling pathways, and their regulation by miRNAs that are known to lead to tumorigenesis. Further, we discuss the current state of miRNA therapeutics in the clinic and their future potential.

Role of microRNAs in osteogenesis of stem cells

Osteogenic differentiation is a controlled developmental process in which external and internal factors including cytokines, growth factors, transcription factors (TFs), signaling pathways and microRNAs (miRNAs) play important roles. Various stimulatory and inhibitory TFs contribute to osteogenic differentiation and are responsible for bone development. In addition, cross-talk between several complex signaling pathways regulates the osteogenic differentiation of some stem cells. Although much is known about regulatory genes and signaling pathways in osteogenesis, the role of miRNAs in osteogenic differentiation still needs to be explored. miRNAs are small, approximately 22 nucleotides, single-stranded nonprotein coding RNAs which are abundant in many mammalian cell types. They paly significant regulated roles in various biological processes and serve as promising biomarkers for disease states. Recently, emerging evidence have shown that miRNAs are the key regulators of osteogenesis of stem cells. They may endogenously regulate osteogenic differentiation of stem cells through direct targeting of positive or negative directors of osteogenesis and depending on the target result in the promotion or inhibition of osteogenic differentiation. This review aims to provide a general overview of miRNAs participating in osteogenic differentiation of stem cells and explain their regulatory effect based on the genes targeted with these miRNAs.

MicroRNA-128 is involved in dexamethasone-induced lipid accumulation via repressing SIRT1 expression in cultured pig preadipocytes

In this study, pig preadipocytes were firstly treated with 10^-6 M DEX for 48 h to explore the role of dexamethasone (DEX, a chemically synthesized long-acting glucocorticoid) on lipid accumulation. Then, miRNA scrambled control (miR-SC), miR-128 overexpression plasmid and miR-128 inhibitor were respectively transfected into pig preadipocytes at 24 h before DEX treatment for 48 h (miR-SC-DEX, miR-128-DEX and miR-128-inhibitor-DEX) to illustrate the regulatory role of miR-128 on DEX-induced lipid accumulation. Compared with control preadipocytes, 10^-6 M Dex significantly increased triglyceride (TG) level, whereas the cell proliferation did not change. Moreover, 10^-6 M Dex obviously decreased sirtuin 1 (SIRT1) and its related lipolysis genes adipose triglyceride lipase (ATGL) and hormone sensitive lipase (HSL) mRNA expression and enzyme activity, while significantly increased expression of adipogenesis genes peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAAT/enhancer binding protein-α (C/EBP-α) and fatty acid synthase (FAS). In addition, 10^-6 M DEX significantly upregulated miR-128 expression, which was confirmed to directly target SIRT1 by bioinformatics analysis and dual-luciferase reporter assay. Gain- and loss-of-function study also showed that when compared with miR-SC-DEX cells, miR-128-DEX cells showed significantly reduced SIRT1 expression and increased TG level, as well as elevated cellular levels of PPAR-γ, C/EBP-α and FAS and suppressed ATGL and HSL expression and enzyme activity. In contrast, miR-128-inhibitor-DEX cells precisely presented the opposite results. Collectively, these results indicate that miR-128 plays a role in the pathogenesis of glucocorticoid-related abnormal lipid accumulation via repressing SIRT1 expression, consequently, miR-128 inhibition may represent a novel potential therapeutic target in preventing DEX-induced abnormal lipid accumulation.

Shortcuts to a functional adipose tissue: The role of small non-coding RNAs

Metabolic diseases such as type 2 diabetes are a major public health issue worldwide. These diseases are often linked to a dysfunctional adipose tissue. Fat is a large, heterogenic, pleiotropic and rather complex tissue. It is found in virtually all cavities of the human body, shows unique plasticity among tissues, and harbors many cell types in addition to its main functional unit - the adipocyte. Adipose tissue function varies depending on the localization of the fat depot, the cell composition of the tissue and the energy status of the organism. While the white adipose tissue (WAT) serves as the main site for triglyceride storage and acts as an important endocrine organ, the brown adipose tissue (BAT) is responsible for thermogenesis. Beige adipocytes can also appear in WAT depots to sustain heat production upon certain conditions, and it is becoming clear that adipose tissue depots can switch phenotypes depending on cell autonomous and non-autonomous stimuli. To maintain such degree of plasticity and respond adequately to changes in the energy balance, three basic processes need to be properly functioning in the adipose tissue: i) adipogenesis and adipocyte turnover, ii) metabolism, and iii) signaling. Here we review the fundamental role of small non-coding RNAs (sncRNAs) in these processes, with focus on microRNAs, and demonstrate their importance in adipose tissue function and whole body metabolic control in mammals.