The flavonoid glycoside vaccarin inhibits adipogenesis and stimulates lipolysis via Hedgehog signaling in 3T3-L1 adipocytes

Vaccarin,a flavonoid glycoside isolated from Vaccaria segetalis,is non-toxic to 3T3-L1 cells up to concentrations of 200μM.Accordingly,we investigated the effects of this natural product on adipogenesis and lipolysis in 3T3-L1 adipocytes.Our results revealed that vaccarin significantly inhibited lipid accumulation by suppressing the adipogenesis-related transcription factors peroxisome proliferator-activated receptorγ(PPARγ)and the CCAAT/enhancer-binding proteinα(C/EBPα).Specifically,lipid accumulation decreased by up to 27.7±2.7%when 3T3-L1 adipocytes were treated with a 10μM concentration of vaccarin.Mechanistic studies showed that the compound inhibited adipogenesis through activation of the Hedgehog(Hh)signaling pathway and so restoring Smo and Gli1 expression at an early stage of differentiation.In mature 3T3-L1 cells,vaccarin significantly increased the secretion of glycerol into the surrounding medium and thus indicating that it accelerated the degradation of triglycerides.In addition,vaccarin,was shown to enhance lipolysis through stimulation of the transcription levels of lipoprotein lipase,monoglycerides lipase,adipose triacylglyceride lipase,hormone-sensitive lipase and adipose differentiated-related protein.All told,vaccarin suppressed lipid accumulation and enhanced lipolysis during adipocyte differentiation by restoring Hh signaling.As such,it is a phytochemical capable of halting adipocyte hyperplasia and,thereby,ameliorating the effects of obesity.

RNA-seq analysis reveals the critical role of the novel lnc RNA BIANCR in intramuscular adipogenesis through the ERK1/2 signaling pathway

Background Long non-coding RNAs(lncRNAs)regulate numerous biological processes,including adipogenesis.Research on adipogenesis will assist in the treatment of human metabolic diseases and improve meat quality in livestock,such as the content of intramuscular fat(IMF).However,the significance of lncRNAs in intramuscular adipogenesis remains unclear.This research aimed to reveal the lncRNAs transcriptomic profiles in the process of bovine intramuscular adipogenesis and to identify the lncRNAs involved in the adipogenesis of bovine intramuscular adipocytes.Results In this research,a landscape of lncRNAs was identified with RNA-seq in bovine intramuscular adipocytes at four adipogenesis stages(0 d,3 d,6 d,and 9 d after differentiation).A total of 7035 lncRNAs were detected,including 3396 novel lncRNAs.Based on the results of differential analysis,co-expression analysis,and functional prediction,we focused on the bovine intramuscular adipogenesis-associated long non-coding RNA(BIANCR),a novel lncRNA that may have an important regulatory function.The knockdown of BIANCR inhibited proliferation and promoted apoptosis of intramuscular preadipocytes.Moreover,BIANCR knockdown inhibited intramuscular adipogenesis by regulating the ERK1/2 signaling pathway.Conclusion This study obtained the landscape of lncRNAs during adipogenesis in bovine intramuscular adipocytes.BIANCR plays a crucial role in adipogenesis through the ERK1/2 signaling pathway.The results are noteworthy for improving beef meat quality,molecular breeding,and metabolic disease research.

m^(6)A demethylase FTO regulate CTNNB1 to promote adipogenesis of chicken preadipocyte

Background:N6-methyladenosine(m^(6)A)is an abundant post-transcriptional RNA modification that affects various biological processes.The fat mass and obesity-associated(FTO)protein,a demethylase encoded by the FTO gene,has been found to regulate adipocyte development in an m^(6)A-dependent manner in multiple species.However,the effects of the m^(6)A methylation and FTO demethylation functions on chicken adipogenesis remain unclear.This study aims to explore the association between m^(6)A modification and chicken adipogenesis and the underlying mechanism by which FTO affects chicken preadipocyte development.Results:The association between m^(6)A modification and chicken lipogenesis was assessed by treating chicken pread-ipocytes with different doses of methyl donor betaine and methylation inhibitor cycloleucine.The results showed that betaine significantly increased methylation levels and inhibited lipogenesis,and the inverse effect was found in preadipocytes after cycloleucine treatment.Overexpression of FTO significantly inhibited m^(6)A levels and promoted proliferation and differentiation of chicken preadipocytes.Silencing FTO showed opposite results.Mechanistically,FTO overexpression increased the expression of catenin beta 1(CTNNB1)by improving RNA stability in an m^(6)A-dependent manner,and we proved that FTO could directly target CTNNB1.Furthermore,CTNNB1 may be a positive regulator of adipogenesis in chicken preadipocytes.Conclusions:m^(6)A methylation of RNA was negatively associated with adipogenesis of chicken preadipocytes.FTO could regulate CTNNB1 expression in a demethylation manner to promote lipogenesis.

Integrative analysis of miRNA and mRNA profiles reveals that gga-miR-106-5p inhibits adipogenesis by targeting the KLF15 gene in chickens

Background:Excessive abdominal fat deposition in commercial broilers presents an obstacle to profitable meat quality,feed utilization,and reproduction.Abdominal fat deposition depends on the proliferation of preadipocytes and their maturation into adipocytes,which involves a cascade of regulatory molecules.Accumulating evidence has shown that microRNAs(miRNAs)serve as post-transcriptional regulators of adipogenic differentiation in mammals.However,the miRNA-mediated molecular mechanisms underlying abdominal fat deposition in chickens are still poorly understood.This study aimed to investigate the biological functions and regulatory mechanism of miRNAs in chicken abdominal adipogenesis.Results:We established a chicken model of abdominal adipocyte differentiation and analyzed miRNA and mRNA expression in abdominal adipocytes at different stages of differentiation(0,12,48,72,and 120 h).A total of 217 differentially expressed miRNAs(DE-miRNAs)and 3520 differentially expressed genes were identified.Target prediction of DE-miRNAs and functional enrichment analysis revealed that the differentially expressed targets were significantly enriched in lipid metabolism-related signaling pathways,including the PPAR signaling and MAPK signaling pathways.A candidate miRNA,gga-miR-106-5p,exhibited decreased expression during the proliferation and differentiation of abdominal preadipocytes and was downregulated in the abdominal adipose tissues of fat chickens compared to that of lean chickens.gga-miR-106-5p was found to inhibit the proliferation and adipogenic differentiation of chicken abdominal preadipocytes.A dual-luciferase reporter assay suggested that the KLF15 gene,which encodes a transcriptional factor,is a direct target of gga-miR-106-5p.gga-miR-106-5p suppressed the posttranscriptional activity of KLF15,which is an activator of abdominal preadipocyte proliferation and differentiation,as determined with gain-and loss-of-function experiments.Conclusions:gga-miR-106-5p functions as an inhibitor of abdominal adipogenesis by targeting the KLF15 gene in chickens.These findings not only improve our understanding of the specific functions of miRNAs in avian adipogenesis but also provide potential targets for the genetic improvement of excessive abdominal fat deposition in poultry.

Tissue Inhibitor of Metalloprotease-1(TIMP-1)Regulates Adipogenesis of Adipose-derived Stem Cells(ASCs)via the Wnt Signaling Pathway in an MMP-independent Manner

Tissue inhibitor of m etalloprotease-1(TIM P-1)is a tissue inhibitor o f matrix metalloproteinases(MMPs).It however exerts multiple effects on biological processes,such as cell growth,proliferation,differentiation and apoptosis,in an MMP-independent manner.This study aimed to examine the role of TIMP-1 in adipogenesis of adipose-derived stem cells(ASCs)and the underlying mechanism.We knocked down the TIMP-1 gene in ASCs through lentiviral vectors encoding TIMP-1 small interfering RNA(siRNA),and then found that the knockdown of TIMP-1 in ASCs promoted the adipogenic differentiation of stem cells and inhibited the Wnt/β-catenin signaling pathway in ASCs.We also noted that mutant TIMP-1 without the inhibitory activity on MMPs promoted the activation of Wnt/β-catenin pathway as well as the recombinant wild type TIMP-1 did,which indicated that the effect of TIMP-1 on Wnt/β-catenin pathway was MMPindependent.Our study suggested that TIMP-1 negatively regulated the adipogenesis of ASCs via the Wnt/β-catenin signaling pathway in an MMP-independent manner.

Three Important Transcription Factors Related to Lipogenesis and Adipogenesis in Mammal

Lipid metabolism and adipocyte differentiation are reglulated by networking of transcription factors. It is generally known that three factors, peroxisome proliferator-activated receptor y （PPARγ）, CCAAT/element-binding protein a （C/EBPa） and sterol regulatory element binding protein-1 （SREBP1）, play fundamental roles in metabolic pathways. And they are also important in adipocyte differentiation. Expressions of these factors are regulated by some compounds such as fatty acids or some steroid hormones （insulin） which is stimulated by the nutritional level. Furthermore, these factors are related to some metabolic diseases including type II diabetes and obesity, Lots of researches have focused on relationships between the factors and the genetic diseases. Different functions of factors on inducing the adipocyte differentiation are other hot spots according to previous studies. This paper summarized these studies and gave a limpid description of structures and functions of these genes.

Adipogenesis Inhibitory Activity of Hypersampsone P from Hypericum subsessile

Adamantane polycyclic polyprenylated acylphloroglucinols(PPAPs)with caged architecture,a special class of hybrid natural products,is specifically rich in the plant family Guttiferae,especially Hypericum or Garcinia genus.Hypersampsone P is one of Adamantane PPAPs compounds extracted from Hypericum subsessile.Here we have chosen,screened ten PPAPs and identified one of them showed an activity in inhibiting of adipocytes differentiation.Particularly,the compound,hypersamp-sone P,blunted the adipocyte differentiation dose-dependently.Moreover,hypersampsone P down-regulated the expressions of several key regulators for adipogenesis,including PPARγand FABP4.The treatment of cells at the early stage of adipo-genesis by hypersampsone P induced the greatest blunting of adipocyte differentiation and the effect might be involved in the LKB1-AMPK signaling pathway.

Long non-coding RNAMIR22HG inhibits the adipogenesis of human bone marrow mesenchymal stem cells with the involvement of Wnt/β-catenin pathway

Osteoporosis is a frequently occurring bone remodeling disorder worldwide with one characteristic being decreasing bone mineral density and a predisposition to bone fracture,which diminishes patients’quality of life.Several studies showed that imbalance between the osteogenesis and adipogenesis of bone marrow mesenchymal stem cells(BMSCs)took part in the development of osteoporosis.In previous study,we found MIR22HG regulated the osteogenesis of human BMSCs positively.In this study,we found that MIR22HG was decreased during the adipogenesis of human BMSCs and exerted negative effects on adipogenesis with the involvement of Wnt/β-catenin signaling pathway both in vitro and in vivo.Nitazoxanide could inhibit Wnt signaling and relieve MIR22HG’s suppression on adipogenesis.These findings indicated that MIR22HG had great potential in clinical application for osteoporosis treatment and prevention.

Pyrocincholic acid 3β-O-β-D-quinovopyranosyl-28-O-β-Dglucopyranoside suppresses adipogenesis and regulates lipid metabolism in 3T3-L1 adipocytes

Obesity is crucially involved in many metabolic diseases,such as type 2 diabetes,cardiovascular disease and cancer.Regulating the number or size of adipocytes has been suggested to be a potential treatment for obesity.In this study,we investigated the effect of pyrocincholic acid 3β-O-β-D-quinovopyranosyl-28-O-β-D-glucopyranoside(PAQG),a 27-nor-oleanolic acid saponin extracted from Metadina trichotoma,on adipogenesis and lipid metabolism in 3T3-L1 adipocytes.The 3T3-L1 pre-adipocytes were incubated with vehicle or PAQG for 6 days in differentiation process.PAQG significantly reduced the adipogenesis,adiponectin secretion and the expression level of key transcription factors related to adipogenesis,such as PPARc,C/EBPb,C/EBPa,and FABP4.Moreover,PAQG increased the levels of FFA and glycerol in medium and reduced TG level in mature adipocytes.Interestingly,PAQG not only promoted the activation of AMPK and genes involved in fatty oxidation including PDK4 and CPT1a,but also inhibited those genes involved in fatty acid biosynthesis,such as SREBP1c,FAS,ACCa and SCD1.In conclusion,PAQG inhibits the differentiation and regulates lipid metabolism of 3T3-L1 cells via AMPK pathway,suggesting that PAQG may be a novel and promising natural product for the treatment of obesity and hyperlipidemia.

Colocynth (<i>Citrullus colocynthis</i>) Flesh Extract Suppresses Adipogenesis by Down-Regulating Adipogenic Transcription Factors and Their Target Genes in 3T3-L1 Preadipocytes

Citrullus colocynthis, a member of the Cucurbitaceae family, is widely distributed in North Africa. The fruits are recognized for their wide range of medicinal uses and promising pharmaceutical potential. The present study aimed to investigate the anti-obesity effect of the ethanol extract of colocynth flesh (FCEE) in 3T3-L1 cells following treatment at different doses. The viability of 3T3-L1 preadipocytes was analyzed via MTT assay and triglycerides were stained with Oil red O to assess lipid accumulation. Additionally, adipogenesis-related gene expression was quantified via qRT-PCR. FCEE (0 - 150 μg/mL) dose-dependently suppressed intracellular triglyceride accumulation during the adipogenesis by 23% and 66% at 100 and 150 μg/mL, respectively, but did not affect cell viability. Analysis of the time-dependence of the effect of FCEE demonstrated that the greatest anti-adipogenic activity was observed during the early stages of differentiation. FCEE also decreased GPDH activity in a dose-dependent manner, with 98% decrease observed at 150 μg/mL. In addition, at same range of FCEE concentrations, the main transcription factors, including CCAAT/enhancer binding protein α (C/EBPα), peroxisome proliferator activated receptor γ (PPARγ), and sterol regulatory element-binding protein 1c (SREBP-1c), were downregulated by 90%, 89%, and 89%, respectively at 150 μg/mL. As these are the master regulators of adipogenesis. The inhibition of their downstream target genes was also observed. Colocynth may be useful in the treatment of obesity owing to its powerful effects on fat, which result in changes to adipocyte differentiation and fat mobilization.

Effect of Androstenedione on Adipogenesis in Murine C3H10T1/2 Mesenchymal Cells

Clinical trials of weak androgen androstenedione (AD) administered at a high concentration, showed an increase in muscle mass in men like strong androgens testosterone (T) and dihydrotestosterone (DHT), but did not show any inhibitory effect on fat mass unlike strong androgens. This observation prompted us to check the in-vitro effect of AD on adipogenesis using mouse mesenchymal multipotent cells (C3H10T1/2), which can differentiate into both myoblasts and adipocytes. Results indicated that AD inhibited adipogenesis at 10 nM, 100 nM and 1 μM concentrations, but not at 10 μM concentration. AD did not inhibit adipogenesis at 10 μM concentration and also did not inhibitmyogenesis at 10 μM concentration. Addition of bicalutamide, an androgen receptor (AR) antagonist decreased myogenesis and increased adipogenesis, indicating that the effect of AD was mediated through AR. Another weak androgen dehydroepiandrosterone (DHEA) also showed the same pattern of adipogenesis in 10T1/2 cells. AD also showed a similar pattern of adipogenesis in 3T3-L1 preadipocyte cells. Thus, the in-vitro results of AD on adipogenesis correlated with the in-vivo results of AD on fat-mass from clinical trials and suggested a possible difference in biological action between weak androgens (AD, DHEA) and strong androgens (T, DHT) on adipogenesis. Since the biological action of AD was mediated through AR, this physiological difference onadipogenesis could be due to the nature (partial agonist/antagonist) of AD binding to AR.

Bisphosphonates and adipogenesis: Evidence for alendronate inhibition of adipocyte differentiation in 3T3-L1 preadipocytes through a vitamin D receptor mediated effect

Background: Adipocyte and osteoblast derive from the same mesenchimal progenitor. Age-related decrease in bone mass is accompanied by an increase in marrow adipose tissue. Vitamin D3 (VD3) inhibits adipogenesis in 3T3-L1 preadipocytes. Recently it has been demonstrated that alendronate (ALN) inhibits adipogenesis while promoting osteoblast differentiation of mesenchimal stem cells. Aim of the Study: To evaluate the role of ALN on adipocyte differentiation in vitro and the potential synergic role of VD3 co-treatment. Procedures: Murine 3T3-L1 and 3T3-F442A preadipocytes were routinely differentiated in presence of ALN and VD3 10-9 - 10-7 M for 7 days and then stained with Oil Red O. The effect of these treatments on mRNA expression of the main molecular markers of adipocyte differentiation (PPARγ and C/EBPα) and VD Receptor (VDR) were analyzed through RT-PCR. Results: Both ALN and VD3 showed a marked anti-adipogenic effect on 3T3-L1 cells. Co-incubation of ALN 10-8 M and VD3 10-9 M displayed no synergic effect on inhibition of adipogenesis. PPARγ mRNA expression was significantly reduced by ALN and VD3. mRNA expression of C/EBPα was reduced only by VD3 treatment. An increase in VDR mRNA expression of 3T3-L1 cells was observed with both ALN and VD3. On the contrary, 3T3-F442A cells, which are in a more advanced adipogenic differentiation stage compared to 3T3-L1, did not express detectable levels of VDR. Interestingly, adipose differentiation of 3T3-F442A was not affected by ALN nor VD3. These results suggest that VDR may represent the molecular target of the anti-adipogenic effect of ALN. Conclusion: VDR plays a critical role in mediating the anti-adipogenic effect of ALN. Further studies to clarify this mechanism are warranted.

Role of sphingosine kinases and sphingosine 1-phosphate in mediating adipogenesis

Recent Background: Development of obesity involves promotion of preadipocyte differrentiation. This study investigated the role that sphingosine kinases (SPHK) and ceramide-derived sphingosine 1-phosphate (S1P) play in adipocyte terminal differentiation. Materials and Methods: The mouse 3T3-L1 cell line was used as a model for adipogenesis. Cells were harvested at specific time points after initation of differentiation, and SPHK activity was measured. 3T3-L1 cells were treated with S1P and expression of early adipogenesis transcription markers was measured by real time PCR. The expression of S1P-receptors (S1PRs) during differentiation was measured. Results: SPHK activity is induced when 3T3-L1 cells are treated with insulin, dexamethasone, and isobutylmethylxanthine to induce differentiation. SPHK1 is active in preadipocytes and early in the differentiation process. Both SPHK1 and SPHK2 isozymes contribute to activity in differentiated adipocytes. Inhibition of SPHK1 attenuates adipocyte differentiation;however, extracellular S1P does not rescue the effect of SPHK1 inhibition on adipogenesis. Although treatment of preadipocytes with S1P induced message expression of the early adipogenesis transcription factor CC AAT/ binding proteinalpha, continued treatment did not fully support the development of differentiated adipocytes. Sphingosine 1-phosphate receptors (S1PRs) are expressed in preadipocytes and message expression declines markedly during adipocyte differentiation. Conclusion: These results demonstrate that the contribution of SPHK and S1P to adipogenesis is mediated primarily through biphasic activation of SPHK1 and 2 with extracellular S1P and S1PRs playing little role during preadipocyte differentiation.

Cyanidine-3-O-Galactoside Enriched <i>Aronia melanocarpa</i>Extract Inhibits Adipogenesis and Lipogenesis via Down-Regulation of Adipogenic Transcription Factors and Their Target Genes in 3T3-L1 Cells

Aronia melamocarpa (AM) is a rich source of anthocyanins, which are known to help prevent obesity. The cyanidine-3-O-galactoside enriched AM extract (AM-Ex) containing more cyanidine-3-O-galactoside than conventional AM extract was recently developed. The objective of this study was to examine the effect of AM-Ex on adipogenesis and its action mechanisms in vitro using 3T3-L1 adipocytes. To examine the anti-obesity effect of AM-Ex, 3T3-L1 cells were induced adipocyte differentiation and incubated with various concentration of AM-Ex. Lipid accumulation, cellular triglyceride content, mRNA expression of transcription factors and adipogenic genes were analyzed. Treatment with 100 - 400 μg/mL of AM-Ex resulted in a dose-dependent decrease in adipocyte differentiation and triglyceride accumulation. mRNA expression of adipogenic transcription factors, such as peroxisome proliferator-activated receptor gamma, CCAAT/enhancer binding protein α, sterol regulatory element-binding protein 1 were decreased. The level of gene expression of adipogenesis and lipogenesis-related genes, such as adipocyte protein 2, lipoprotein lipase, acetyl-CoA carboxylase, ATP-citrate lyase and fatty acid synthase were decreased. These results suggest that AM-Ex alleviated risk factors related to obesity by modulating multiple pathways associated with adipogenesis.

Unraveling the relationship between histone methylation and nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD)poses a significant health challenge in modern societies due to shifts in lifestyle and dietary habits.Its complexity stems from genetic predisposition,environmental influences,and metabolic factors.Epigenetic processes govern various cellular functions such as transcription,chromatin structure,and cell division.In NAFLD,these epigenetic tendencies,especially the process of histone methylation,are intricately intertwined with fat accumulation in the liver.Histone methylation is regulated by different enzymes like methyltransferases and demethylases and influences the expression of genes related to adipogenesis.While early-stage NAFLD is reversible,its progression to severe stages becomes almost irreversible.Therefore,early detection and intervention in NAFLD are crucial,and understanding the precise role of histone methylation in the early stages of NAFLD could be vital in halting or potentially reversing the progression of this disease.

Effect of methyl tert-butyl ether on adipogenesis and glucose metabolism in vitro and in vivo

Methyl tert-butyl ether (MTBE),as a widely used gasoline additive,is suspected of being environmentally toxic.MTBE accumulates mainly in adipose tissue,but its effect on obesity or obesity-related metabolic disorders has not been well understood yet.Therefore,we examined the effect of MTBE on the adipose function and the related metabolic processes with both 3T3-L1 cell line and C57BL/6J mice model.We found that exposure to MTBE at the environmental relevant concentration (100 μmol/L) could significantly induce differentiation of preadipocyte and disturb insulin-stimulated glucose uptake of mature adipocyte.The in vivo observation in male mice showed a positive correlation of visceral white adipose tissue (vWAT) expansion and cell size increase with MTBE treatment in 14 weeks.Glucose tolerance and insulin sensitivity tests demonstrated that MTBE at 1000 μg/(kg·day) disturbed the systemic glucose metabolism in a gender-specific manner,which might be partly attributed to the alterations of gut microbiota community at genus level with respect to Akkermansia,Clostridium XIVb,and Megamonas.In summary,our study characterized the effect of MTBE on adipose tissue function and glucose homeostasis in vitro and in vivo,and revealed that systemic disorders of the glucose metabolism might be modulated by the related gut microbiota.

Epigenetic regulation of adipocyte differentiation and adipogenesis

It is generally agreed that adipocytes originate from mesenchymal stem cells in what can be divided into two processes:determination and differentiation.In the past decade,many factors associated with epigenetic signals have been proved to be pivotal for the appropriate timing of adipogenesis progression.A large number of coregulators at critical gene promoters set up specific patterns of DNA methylation,histone acetylation and methylation,and nucleosome rearrangement,that act as an epigenetic code to modulate the correct progress of adipocyte differentiation and adipogenesis during adipogenesis.In this review,we focus on the functions and roles of epigenetic processes in preadipocyte differentiation and adipogenesis.

Cytokines and inflammation in adipogenesis:an updated review

The biological relevance of cytokines is known for more than 20 years.Evidence suggests that adipogenesis is one of the biological events involved in the regulation of cytokines,and pro-inflammatory cytokines (e.g.,TNFα and IL-1β)inhibit adipogenesis through various pathways.This inhibitory effect can constrain the hyperplastic expandability of adipose tissues.Meanwhile,chronic low-grade inflammation is commonly observed in obese populations.In some individuals,the impaired ability of adipose tissues to recruit new adipocytes to adipose depots during overnutrition results in adipocyte hypertrophy,ectopic lipid accumulation,and insulin resistance.Intervention studies showed that pro-inflammatory cytokine antagonists improve metabolism in patients with metabolic syndrome.This review focuses on the cytokines currently known to regulate adipogenesis under physiological and pathophysiological circumstances.Recent studies on how inhibited adipogenesis leads to metabolic disorders were summarized.Although the interplay of cytokines and lipid metabolism is yet incompletely understood,cytokines represent a class of potential therapeutic targets in the treatment of metabolic disorders.

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.

Chemerin deficiency regulates adipogenesis is depot different through TIMP1

Adipocytes and immune cells are vital for the development of adipose tissue.Adi-pokines secreted by adipocytes regulate adipogenesis and body metabolism.Chemerin is one of the adipokines.However,the function and mechanism of chemerin in adipose tissue are not fully illuminated.Compared with wild type(WT)mice,Rarres2^(-/-)mice gained weight and significantly increased fat distribution in subcutaneous adipose tissue(SAT),rather than visceral adipose tissue(VAT)on high fat diet(HFD).PPARg and C/EBPa,the master regulators of adipogenesis,were up-regulated in SAT and down-regulated in VAT in Rarres2^(-/-)mice comparing with WT mice.Inspite of chemerin deficiency or not,the ratio of adipocyte-progenitors to total cells and the differentiation capacity of adipocyte-progenitors were similar in SAT and VAT,but macrophage infiltration in VAT was more severe than in SAT in Rarres2^(-/-)mice.Furthermore,CD45þimmune cells supernatant from Rarres2^(-/-)SAT pro-moted the differentiation of adipocyte-progenitors and 3T3-L1 cells.Adipokine array assay of CD45þimmune cells supernatant revealed that metalloproteinase inhibitor 1(TIMP1),an in-hibitor of adipogenesis,was reduced in Rarres2^(-/-)SAT,but increased in Rarres2^(-/-)VAT.As we specifically knocked down chemerin in SAT,TIMP1 was down-regulated and adipogenesis was promoted with reducing infiltration of macrophages.The present study demonstrates that the effects of chemerin on adipose tissue is depot different,and specific knock down chemerin in SAT promote adipogenesis and improve glucose tolerance test(GTT)and insulin tolerance test(ITT).This suggests a potential therapeutic target for chemerin in the treatment of obesity related metabolic disorder.