miR-23a/b regulates the balance between osteoblast and adipocyte differentiation in bone marrow mesenchymal stem cells

Age-related osteoporosis is associated with the reduced capacity of bone marrow mesenchymal stem cells （BMSCs） to differentiate into osteoblasts instead of adipocytes. However, the molecular mechanisms that decide the fate of BMSCs remain unclear. In our study, microRNA-23a, and microRNA-23b （miR-23a/b） were found to be markedly downregulated in BMSCs of aged mice and humans. The overexpression of miR-23a/b in BMSCs promoted osteogenic differentiation, whereas the inhibition of miR-23a/b increased adipogenic differentiation. Transmembrane protein 64 （Tmem64）, which has expression levels inversely related to those of miR-23a/b in aged and young mice, was identified as a major target of miR-23a/b during BMSC differentiation. In conclusion, our study suggests that miR-23a/b has a critical role in the regulation of mesenchymal lineage differentiation through the suppression of Tmem64.

A Triterpenoid Inhibited Hormone-Induced Adipocyte Differentiation and Alleviated Dexamethasone-Induced Insulin Resistance in 3T3-L1 adipocytes

6a-Hydroxylup-20(29)-en-3-on-28-oic acid(1),a natural triterpenoid,was found to possess the ability in a dose-dependent manner inhibiting hormone-induced adipocyte differentiation in 3T3-L1 preadipocytes,and restoring glucose consuming ability in dexamethasone(DXM)-induced insulin resistant 3T3-L1 adipocytes.Compound 1 was also found to ameliorate DXM-induced adipocyte dysfunction in lipolysis and adipokine secretion.Mechanistic studies revealed that 1 inhibited adipocyte differentiation in 3T3-L1 preadipocytes via down-regulating hormone-stimulated gene transcription of peroxisome proliferator-activated receptor c and CCAAT-enhancer-binding protein alpha which are key factors in lipogenesis,and restored DXM-impaired glucose consuming ability in differentiated 3T3-L1 adipocytes via repairing insulin signaling pathway and activating down-stream signaling transduction by phosphorylation of signaling molecules PI3K/p85,Akt2 and AS160,thus leading to increased translocation of glucose transporter type 4 and transportation of glucose.

MYOD1 inhibits avian adipocyte differentiation via miRNA-206/KLF4 axis

Background:A considerable number of muscle development-related genes were differentially expressed in the early stage of avian adipocyte differentiation.However,the functions of them in adipocyte differentiation remain largely known.In this study,the myoblast determination protein 1(MYOD1)was selected as a representative of muscle development.We investigated its expression,function,and regulation in avian adipocyte differentiation.Results:The expression of MYOD1 decreased significantly in the early stage of avian adipocyte differentiation.CRIS PR/Cas9-mediated deletion of MYOD1 induced adipocyte differentiation,whereas over-expression of MYOD1 inhibited adipogenesis.The mRNA-seq data showed that MYOD1 could perturb the lipid biosynthetic process during differentiation.Our results showed that MYOD1 directly up-regulates the miR-206 expression by binding the upstream 1200 bp region of miR-206.Then,over-expression of miR-206 can inhibit the adipogenesis.Furthermore,MYOD1 affected the expression of endogenous miR-206 and its target gene Kruppel-like factor 4(KLF4),which is an important activator of adipogenesis.Accordingly,the inhibition of miR-206 or over-expression of KLF4 could counteract the inhibitory effect of MYOD1 on adipocyte differentiation.Conclusions:Our results establish that MYOD1 inhibits adipocyte differentiation by up-regulating miR-206 to suppress the KLF4 expression.These findings identify a novel function of MYOD1 in adipocyte differentiation,suggesting a potential role in body-fat distribution regulation.

Eriocalyxin B Inhibits Adipogenesis in 3T3-L1 Adipocytes by Cell Cycle Arrest

Eriocalyxin B,an ent-Kaurene diterpenoid extracted from a traditional Chinese herb Isodon eriocalyx,has been shown to possess multifunctional activities such as anti-cancer and anti-inflammatory.However,the function and mechanism of the compound in adipocyte differentiation is still unknown.Here we reported that eriocalyxin B blunted adipogenesis remarkably by inhibiting the accumulation of lipid droplets,triglycerides and the expressions of adipogenesis-related factors,including C/EBPβ,C/EBPα,PPARγ,and FABP4.Moreover,we showed that the inhibition might be the consequence of cell cycle being arrested at the G2/M phase during the mitotic clonal expansion of adipocyte differentiation,most likely by suppress-ing mRNAs and proteins of CDK1,CDK2,Cyclin A and Cyclin B1.Overall,we conclude that eriocalyxin B is capable of inhibiting adipocyte differentiation at the early stage through downregulating the proteins involved in cell cycle progression.

Carya cathayensis Leaf Extract Exerts Estrogenic Effects on Hepatic Lipogenesis and Adipocytes Differentiation in Ovariectomized Rats Fed Normal or High-fat Diets

Background:Our previous in vitro study has shown that total flavonoids from the leaves of Carya cathayensis exert estrogenic activities by promoting the expressions of ER𝛼and ER𝛽.C.cathayensis leaf extract(CCE)was rich in flavonoids.Oral administration of CCE reduced the serum lipids and hepatic lipids,alleviated liver steatosis in ovariectomized rats.Objective:To investigate whether CCE has estrogenic effects on reproductive tissue and influences lipid metabolism in ovariectomized rats,and whether CCE has a direct effect on regulation of lipid synthesis and/or oxidation and adipocyte differentiation of ovariectomized(OVX)rats.Methods:Female Sprague-Dawley rats were ovariectomized and treated with CCE or estradiol in combination with a normal diet(ND),a high-fat diet(HFD)for 8 weeks.Histological analysis of uterus were performed and the lipid metabolism-related enzyme activity were examined.Expression of liver lipogenesis-related genes,adipocyte differentiation-and fat accumulation-related genes and protein were measured.Rusults:Ovariectomy accelerated the uterine atrophy,development of dyslipidemia and hepatic steatosis,which were effectively mitigated by CCE supplementation.CCE significantly elevated ovariectomy-induced reduction in the cross-section area of the uterus and uterine glands.Compared with the OVX group,CCE increased the activities of lipoprtein lipase(LPL)and hepatic lipase(HL),decreased the hepatic mRNA expressions of Fas,Srebf1,Sla2a2,and increased Ppar𝛼expressions at the mRNA levels under both ND and HFD conditions.CCE also decreased the Pck1 and G6pc mRNA expressions under HFD conditions,and show no significant effects on Hmgcr.The expressions of SREBF1,CEBPA and VEGF at the protein level were effectively regulated by CCE supplementation.Conclusion:CCE effectively alleviated ovariectomy-induced dyslipidemia and visceral fat accumulation by mod-ulating hepatic lipogenesis and adipocyte differentiation.Furthermore,CCE exhibited estrogenic activity for the prevention of postmenopausal fatty liver.

Fucoidans from Thelenota ananas with 182.4 kDa Exhibited Optimal Anti-Adipogenic Activities by Modulating the Wnt/β-Catenin Pathway

In this study,fucoidans were extracted from the sea cucumber Thelenota ananas(Ta-FUCs)by enzymatic degradation.Four products with molecular weights of 1380.3,524.0,182.4,and 110.3 kDa were obtained,and the Ta-FUC showing optimal anti-adipogenic activities was determined.Results of MTT and Oil red O staining analyses showed that the Ta-FUCs inhibited the proliferation and differentiation of 3T3-L1 adipocytes.Futhermore,Ta-FUCs significantly downregulated the key transcriptional factors,such as SREBP-1c,PPARγ,and C/EBPαof adipocytes.The Ta-FUCs also activated Wnt/β-catenin pathway-related genes,such asβ-catenin,LRP5,and FrZ.The Ta-FUCs suppressed lipid accumulation in 3T3-L1 adipocytes possibly by decreasing the expression of genes ACC,FAS,ME,GPAT,DGAT,and PILN,which are important in the synthesis of fatty acids and triglycerides;and by increasing the expression of genes PPARα,CPT-1α,and ACOX,which are crucial in fatty acidβ-oxidation.The anti-adipogenic activities initially increased and then declined with decreasing molecular weight.Among the Ta-FUCs,the 182.4 kDa Ta-FUC exhibited optimal bioactivities.This study reports for the first time that Ta-FUCs can prevent obesity by regulating the differentiation and lipid accumulation of adipocytes.

Circadian clock control of MRTF/SRF pathway suppresses beige adipocyte thermogenic recruitment

The morphological transformation of adipogenic progenitors into mature adipocytes requires dissolution of actin cytoskeleton with loss of myocardin-related transcription factor(MRTF)/serum response factor(SRF)activity.Circadian clock confers temporal control in adipogenic differentiation,while the actin cytoskeleton–MRTF/SRF signaling transduces extracellular physical niche cues.Here,we define a novel circadian transcriptional control involved in actin cytoskeleton–MRTF/SRF signaling cascade that modulates beige fat thermogenic function.Key components of actin dynamic–MRTF/SRF pathway display circadian regulation in beige fat depot.The core clock regulator,brain and muscle arnt-like 1(Bmal1),exerts direct transcriptional control of genes within the actin dynamic–MRTF/SRF cascade that impacts actin cytoskeleton organization and SRF activity.Employing beige fat-selective gene-targeting models together with pharmacological rescues,we further demonstrate that Bmal1 inhibits beige adipogenesis and thermogenic capacity in vivo via the MRTF/SRF pathway.Selective ablation of Bmal1 induces beigeing with improved glucose homeostasis,whereas its targeted overexpression attenuates thermogenic induction resulting in obesity.Collectively,our findings identify the clock–MRTF/SRF regulatory axis as an inhibitory mechanism of beige fat thermogenic recruitment with significant contribution to systemic metabolic homeostasis.

Hedgehog signaling pathway regulated the target genes for adipogenesis in silkworm Bombyx moil

Hedgehog （Hh） signals regulate invertebrate and vertebrate development, yet the role of the pathway in adipose development remains poorly understood. In this report, we found that Hh pathway components are expressed in the fat body of silkworm larvae. Functional analysis of these components in a BmN cell line model revealed that activa- tion of the Hh gene stimulated transcription of Hh pathway components, but inhibited the expression of the adipose marker gene AP2. Conversely, specific RNA interference- mediated knockdown of Hh resulted in increased AP2 expression. This further showed the regulation of Hh signal on the adipose marker gene. In silkworm larval models, enhanced adipocyte differentiation and an increase in adipocyte cell size were observed in silkworms that had been treated with a specific Hh signaling pathway antagonist, cyclopamine. The fat-body-specific Hh blockade tests were consistent with Hh signaling inhibiting silkworm adipogenesis. Our results indicate that the role of Hh signaling in inhibiting fat formation is conserved in vertebrates and invertebrates.