Transcriptional control of adipogenesis

Nkx1.2 deletion decreases fat production in zebrafish

OBJECTIVE

This study aimed to investigate the role of Nkx1-2, a transcription factor with the NK homeobox domain, in the regulation of fat production.

METHODS

Gene expression was analyzed using quantitative real-time polymerase chain reaction or transcriptome sequencing. CRISPR/Cas9 technology was employed to generate nkx1.2 knockout zebrafish and nkx1.2-deleted 3T3-L1 cells. Lipid droplet production in zebrafish larvae was visually quantified using Nile red staining, whereas lipid droplets in 3T3-L1 cells were stained with Oil red O. The binding of Nkx1-2 to the promoter was verified through an electrophoretic mobility shift assay experiment.

RESULTS

Nkx1-2 plays crucial roles in the regulation of fat production in zebrafish. Knockout of nkx1.2 in zebrafish leads to weight loss, accompanied by significantly reduced lipid droplet production and decreased visceral and liver fat content. Furthermore, genes related to lipid biosynthesis are significantly downregulated. In 3T3-L1 preadipocytes, Nkx1-2 induces differentiation into mature adipocytes by binding to the cebpa promoter, thereby activating its transcription. Additionally, the expression of nkx1.2 is regulated by the p38 MAPK, JNK, or Smad2/3 signaling pathways in 3T3-L1 cells.

CONCLUSIONS

Our findings suggest that Nkx1-2 functions as a positive regulator of fat production, playing a critical role in adipocyte differentiation and lipid biosynthesis.

Rapid direct conversion of bovine non-adipogenic fibroblasts into adipocyte-like cells by a small-molecule cocktail

Introduction: The molecular regulation mechanism of fat deposition in bovine and its improvement on beef quality are important research directions in the livestock industry. The research of molecular mechanisms that govern the regulation and differentiation of adipocytes may conduct to understand the mechanism of obesity, lipid disorders, and fat deposition. In the recent decade, small-molecule compounds have been widely used in reprogramming and transdifferentiation fields, which can promote the induction efficiency, replace exogenous genes, or even induce cell fate conversion alone. Furthermore, small-molecule compound induction is expected to be a novel approach to generate new cell types from somatic cells in vitro and in vivo. Methods: In this study, we established rapid chemically induced platform for transdifferentiation of bovine ear fibroblasts into adipocyte-like cells using a small-molecule cocktail (Repsox, VPA, TTNPB). The chemically induced adipocytes (CiADCs) were characterized by lipid staining, qRT-PCR and WB. Bovine natural adipocytes were used as positive control, and the expression of adipocyte-related marker genes in CiADCs were analyzed. Moreover, RNA-Seq explore the mechanism of RVB in the regulation of Bovine adipocyte transdifferentiation. Results: In this study, the chemically induced adipocytes (CiADCs) could be identified as early as day 6. The CiADCs appeared to be circular and rich of lipid droplets. The adipocyte-specific genes of LPL, PPARγ, IGF1, GPD1, C/EBPδ, ADIPOQ, PCK2, FAS, C/EBPβ, PPARGC1A, C/EBPα, and CFD were detected to be significantly upregulated in both CiADCs and natural adipocytes. Western blot analysis also confirmed the increase C/EBPα and PPARγ protein level in induced adipocytes (CiADCs-6d) treated with RVB. In addition, we also found that the signaling pathways (PPAR signaling pathway, PI3K-Akt signaling pathway, p53 signaling pathway, MAPK signaling pathway, and ECM-receptor interaction) regulated by the DEGs played a vital role in adipogenesis. Discussion: In the present study, a combination of small-molecule compounds RVB was used to transdifferentiate bovine ear fibroblasts into the chemically-induced adipocyte cells (CiADCs) that have a large number of lipid droplets. Importantly, the small-molecule cocktail significantly shortened the reprogramming turnaround time. The morphology of CiADCs is close to the "ring type" of natural differentiated adipocytes on sixth day. And, the CiADCs showed similar adipocyte-specific gene expression patterns to natural adipocytes. Furthermore, RVB increased protein expression of PPARγ and C/EBPα in the chemically-induced adipocytes (CiADCs-6d). Our findings reveal that the signaling pathways of C/EBPα and PPARγ play pivotal roles in this transdifferentiation process. In addition, we also found that the signaling pathways (PPAR signaling pathway, PI3K-Akt signaling pathway, p53 signaling pathway, MAPK signaling pathway, and ECM-receptor interaction) regulated by the DEGs played a vital role in adipogenesis. In general, this study provides valuable evidence to deepen our understanding of the molecular mechanism of small molecule cocktails in regulating adipogenesis.

Lnc-TRTMFS promotes milk fat synthesis via the miR-132x/RAI14/mTOR pathway in BMECs

As an important index to evaluate the quality of milk, milk fat content directly determines the nutrition and flavor of milk. Recently, growing evidence has suggested that long noncoding RNAs (lncRNAs) play important roles in bovine lactation, but little is known about the roles of lncRNAs in milk fat synthesis, particularly the underlying molecular processes. Therefore, the purpose of this study was to explore the regulatory mechanism of lncRNAs in milk fat synthesis. Based on our previous lncRNA-seq data and bioinformatics analysis, we found that Lnc-TRTMFS (transcripts related to milk fat synthesis) was upregulated in the lactation period compared to the dry period. In this study, we found that knockdown of Lnc-TRTMFS significantly inhibited milk fat synthesis, resulting in a smaller amount of lipid droplets and lower cellular triacylglycerol levels, and significantly decreased the expression of genes related to adipogenesis. In contrast, overexpression of Lnc-TRTMFS significantly promoted milk fat synthesis in bovine mammary epithelial cells (BMECs). In addition, Bibiserv2 analysis showed that Lnc-TRTMFS could act as a molecular sponge for miR-132x, and retinoic acid induced protein 14 (RAI14) was a potential target of miR-132x, which was further confirmed by dual-luciferase reporter assays, quantitative reverse transcription PCR, and western blots. We also found that miR-132x significantly inhibited milk fat synthesis. Finally, rescue experiments showed that Lnc-TRTMFS could weaken the inhibitory effect of miR-132x on milk fat synthesis and rescue the expression of RAI14. Taken together, these results revealed that Lnc-TRTMFS regulated milk fat synthesis in BMECs via the miR-132x/RAI14/mTOR pathway.

Fuzhuan brick tea extract prevents diet-induced obesity via stimulation of fat browning in mice

Fuzhuan brick tea is a post-fermented tea that is intentionally fermented by the fungus Eurotium cristatum. Previous studies have reported the anti-obesity effect of Fuzhuan brick tea extracts (FBT), but the underlying mechanism remains unclear. The present study investigated whether FBT exerts anti-obesity effects through energy expenditure and browning of white adipose tissue. Mice were administered 100 mg or 200 mg FBT/kg body weight along with a high-fat diet (HFD) for 12 weeks; the FBT group had a significantly reduced body weight and adipose tissue mass compared to mice fed an HFD alone. FBT also improved serum biochemical parameters and hepatic steatosis concomitant with obesity. Furthermore, FBT enhanced energy expenditure and promoted browning of subcutaneous adipose tissue by upregulating the expression of brown adipocyte-specific genes, including uncoupling protein 1. Based on these results, we suggest that FBT induces energy expenditure by promoting the browning of subcutaneous adipose tissue, which prevents weight gain.

Heme oxygenase-1 induction by gallic acid-g-chitosan is an important event in modulating adipocyte differentiation

Obesity, one of the common worldwide chronic health diseases co-relates with adipogenesis. Adipogenesis is a complex biological action of the emergence of mature adipocytes from the differentiation of pre-adipocytes and the disfunction of this process leads to the development of metabolic issues in obesity. Recently, much attention has been paid to utilizing natural compounds to discover their biological activities. This study focused on investigating the probable anti-adipogenic effects of gallic acid-g-chitosan (GAC) and plain chitosan (PC) through regulating the heme oxygenase-1 (HO-1)/Nrf2 pathway on mesenchymal stem cells. Gallic acid is grafted onto the PC backbone to improve its specific physical and biological properties. GAC showed promising anti-adipogenic effects by enhancing HO-1 expression and lipolysis and as well as suppressing lipid accumulation, reactive oxygen species, and pro-inflammatory cytokines production, transcription factor expression compared to the PC treatment. On the contrary, zinc protoporphyrin ІX (ZnPP), a HO-1 inhibitor reversed these effects of GAC on adipogenesis. Taken all together, this study revealed that grafting GA onto the chitosan improved potential anti-adipogenic activity by induction of the HO-1/Nrf2 pathway on mesenchymal stem cells (MSCs). PRACTICAL APPLICATIONS: GAC is a well-known copolymer with versatile bioactivities such as antimicrobial, antioxidant, and anti-diabetic activity. However, the anti-adipogenic effect of GAC has not been explored in MSCs. This study demonstrated that GAC inhibited adipocyte differentiation in MSCs through HO-1 activation. These findings suggest that GAC can be applied practically from different perspectives. GAC can be applied in the pharmacological industry to the development of anti-obesity drugs, medicinal perspectives for the treatment of obesity and obesity-related diseases, and in the food industry as a functional food to promote health and decrease the risk of diseases.

Biological Prescience: The Role of Anticipation in Organismal Processes

Anticipation is the act of using information about the past and present to make predictions about future scenarios. As a concept, it is predominantly associated with the psychology of the human mind; however, there is accumulating evidence that diverse taxa without complex neural systems, and even biochemical networks themselves, can respond to perceived future conditions. Although anticipatory processes, such as circadian rhythms, stress priming, and cephalic responses, have been extensively studied over the last three centuries, newer research on anticipatory genetic networks in microbial species shows that anticipatory processes are widespread, evolutionarily old, and not simply reserved for neurological complex organisms. Overall, data suggest that anticipatory responses represent a unique type of biological processes that can be distinguished based on their organizational properties and mechanisms. Unfortunately, an empirically based biologically explicit framework for describing anticipatory processes does not currently exist. This review attempts to fill this void by discussing the existing examples of anticipatory processes in non-cognitive organisms, providing potential criteria for defining anticipatory processes, as well as their putative mechanisms, and drawing attention to the often-overlooked role of anticipation in the evolution of physiological systems. Ultimately, a case is made for incorporating an anticipatory framework into the existing physiological paradigm to advance our understanding of complex biological processes.

Torreya nucifera seed oil improves 3T3-L1 adipocyte differentiation

BACKGROUND

Adipose tissue is a critical regulator of lipid storage and endocrine function. Impairment of the recruitment of new adipocytes in the adipose tissue is associated with ectopic fat accumulation, diabetes and insulin resistance. Torreya nucifera, an evergreen conifer that grows in warm temperate climates, has been found to exert beneficial effects against inflammation, infection and diabetes. However, the molecular mechanisms responsible for these effects at the cellular level remain unknown. This study aimed to investigate effects of Torreya nucifera seed oil (TNSO) on 3T3-L1 adipocyte differentiation and its underlying regulatory mechanism.

METHODS

To investigate the effects of TNSO on adipocyte differentiation, 3T3-L1 cells were induced to differentiate for 5 days in the presence of 0.75 μL/mL TNSO. Oil Red O staining and an assay for intracellular triglyceride were performed to determine the extent of lipid accumulation in 3T3-L1 cells. To elucidate the underlying mechanism of TNSO, adipogenic gene expression was analyzed using quantitative real-time PCR. Moreover, we monitored TNSO-derived activation of PPARγ and STAT3 with 3T3-L1 reporter cell lines engineered to secrete Gaussia luciferase upon the interaction of a transcription factor to its DNA binding element.

RESULTS

Oil Red O staining revealed that TNSO improved the differentiation of 3T3-L1 preadipocytes into mature adipocytes. The mRNA levels of adipogenic genes, including adiponectin, fatty acid synthase (FAS) and adipocyte fatty acid-binding protein (FABP4), were upregulated and intracellular triglyceride levels increased upon TNSO treatment. We also established that adipocyte differentiation was improved by TNSO-derived activation of PPARγ and STAT3.

CONCLUSIONS

Our results suggest that TNSO improves adipocyte differentiation by regulating the activation of adipogenic transcription factors, indicating that it may serve as a potential treatment strategy for adipocyte dysfunction.

Roles of MicroRNAs in Osteogenesis or Adipogenesis Differentiation of Bone Marrow Stromal Progenitor Cells

Bone marrow stromal cells (BMSCs) are multipotent cells which can differentiate into chondrocytes, osteoblasts, and fat cells. Under pathological stress, reduced bone formation in favour of fat formation in the bone marrow has been observed through a switch in the differentiation of BMSCs. The bone/fat switch causes bone growth defects and disordered bone metabolism in bone marrow, for which the mechanisms remain unclear, and treatments are lacking. Studies suggest that small non-coding RNAs (microRNAs) could participate in regulating BMSC differentiation by disrupting the post-transcription of target genes, leading to bone/fat formation changes. This review presents an emerging concept of microRNA regulation in the bone/fat formation switch in bone marrow, the evidence for which is assembled mainly from in vivo and in vitro human or animal models. Characterization of changes to microRNAs reveals novel networks that mediate signalling and factors in regulating bone/fat switch and homeostasis. Recent advances in our understanding of microRNAs in their control in BMSC differentiation have provided valuable insights into underlying mechanisms and may have significant potential in development of new therapeutics.

The Role of Lipid Sensing Nuclear Receptors (PPARs and LXR) and Metabolic Lipases in Obesity, Diabetes and NAFLD

Obesity and type 2 diabetes mellitus (T2DM) are metabolic disorders characterized by metabolic inflexibility with multiple pathological organ manifestations, including non-alcoholic fatty liver disease (NAFLD). Nuclear receptors are ligand-dependent transcription factors with a multifaceted role in controlling many metabolic activities, such as regulation of genes involved in lipid and glucose metabolism and modulation of inflammatory genes. The activity of nuclear receptors is key in maintaining metabolic flexibility. Their activity depends on the availability of endogenous ligands, like fatty acids or oxysterols, and their derivatives produced by the catabolic action of metabolic lipases, most of which are under the control of nuclear receptors. For example, adipose triglyceride lipase (ATGL) is activated by peroxisome proliferator-activated receptor γ (PPARγ) and conversely releases fatty acids as ligands for PPARα, therefore, demonstrating the interdependency of nuclear receptors and lipases. The diverse biological functions and importance of nuclear receptors in metabolic syndrome and NAFLD has led to substantial effort to target them therapeutically. This review summarizes recent findings on the roles of lipases and selected nuclear receptors, PPARs, and liver X receptor (LXR) in obesity, diabetes, and NAFLD.

Asc-1 regulates white versus beige adipocyte fate in a subcutaneous stromal cell population

Adipose tissue expansion, as seen in obesity, is often metabolically detrimental causing insulin resistance and the metabolic syndrome. However, white adipose tissue expansion at early ages is essential to establish a functional metabolism. To understand the differences between adolescent and adult adipose tissue expansion, we studied the cellular composition of the stromal vascular fraction of subcutaneous adipose tissue of two and eight weeks old mice using single cell RNA sequencing. We identified a subset of adolescent preadipocytes expressing the mature white adipocyte marker Asc-1 that showed a low ability to differentiate into beige adipocytes compared to Asc-1 negative cells in vitro. Loss of Asc-1 in subcutaneous preadipocytes resulted in spontaneous differentiation of beige adipocytes in vitro and in vivo. Mechanistically, this was mediated by a function of the amino acid transporter ASC-1 specifically in proliferating preadipocytes involving the intracellular accumulation of the ASC-1 cargo D-serine.

Adipose tissue is composed of a variety of cell types, including adipocyte precursor populations, that contribute to adipose tissue function upon differentiation. Here, using scRNA-sequencing of adolescent and adult mouse subcutaneous adipose tissue, the authors identify an Asc-1 positive preadipocyte population that is enriched in adolescent subcutaneous fat and demonstrate that loss of Asc-1 triggers spontaneous beige adipocyte differentiation.

Direct Conversion of Human Fibroblasts into Adipocytes Using a Novel Small Molecular Compound: Implications for Regenerative Therapy for Adipose Tissue Defects

There is a need in plastic surgery to prepare autologous adipocytes that can be transplanted in patients to reconstruct soft tissue defects caused by tumor resection, including breast cancer, and by trauma and other diseases. Direct conversion of somatic cells into adipocytes may allow sufficient functional adipocytes to be obtained for use in regeneration therapy. Chemical libraries of 10,800 molecules were screened for the ability to induce lipid accumulation in human dermal fibroblasts (HDFs) in culture. Chemical compound-mediated directly converted adipocytes (CCCAs) were characterized by lipid staining, immunostaining, and qRT-PCR, and were also tested for adipokine secretion and glucose uptake. CCCAs were also implanted into mice to examine their distribution in vivo. STK287794 was identified as a small molecule that induced the accumulation of lipid droplets in HDFs. CCCAs expressed adipocyte-related genes, secreted adiponectin and leptin, and abundantly incorporated glucose. After implantation in mice, CCCAs resided in granulation tissue and remained adipose-like. HDFs were successfully converted into adipocytes by adding a single chemical compound, STK287794. C/EBPα and PPARγ were upregulated in STK287794-treated cells, which strongly suggests involvement of these adipocyte-related transcription factors in the chemical direct conversion. Our method may be useful for the preparation of autogenous adipocytes for transplantation therapy for soft tissue defects and fat tissue atrophy.

Current treatment paradigms and emerging therapies for NAFLD/NASH

Non-alcoholic fatty liver disease (NAFLD) is one the fastest emerging manifestations of the metabolic syndrome worldwide. Non-alcoholic steatohepatitis (NASH), the progressive form of NAFLD, may culminate into cirrhosis and hepatocellular cancer (HCC) and is presently a leading cause of liver transplant. Although a steady progress is seen in understanding of the disease epidemiology, pathogenesis and identifying therapeutic targets, the slowest advancement is seen in the therapeutic field. Currently, there is no FDA approved therapy for this disease and appropriate therapeutic targets are urgently warranted. In this review we discuss the role of lifestyle intervention, pharmacological agents, surgical approaches, and gut microbiome, with regard to therapy for NASH. In particular, we focus the role of insulin sensitizers, thyroid hormone mimetics, antioxidants, cholesterol lowering drugs, incretins and cytokines as therapeutic targets for NASH. We highlight these targets aiming to optimize the future for NASH therapy.

Leptin: Master Regulator of Biological Functions that Affects Breathing

Obesity is a global epidemic in developed countries accounting for many of the metabolic and cardiorespiratory morbidities that occur in adults. These morbidities include type 2 diabetes, sleep-disordered breathing (SDB), obstructive sleep apnea, chronic intermittent hypoxia, and hypertension. Leptin, produced by adipocytes, is a master regulator of metabolism and of many other biological functions including central and peripheral circuits that control breathing. By binding to receptors on cells and neurons in the brainstem, hypothalamus, and carotid body, leptin links energy and metabolism to breathing. In this comprehensive article, we review the central and peripheral locations of leptin's actions that affect cardiorespiratory responses during health and disease, with a particular focus on obesity, SDB, and its effects during early development. Obesity-induced hyperleptinemia is associated with centrally mediated hypoventilation with decrease CO₂ sensitivity. On the other hand, hyperleptinemia augments peripheral chemoreflexes to hypoxia and induces sympathoexcitation. Thus, "leptin resistance" in obesity is relative. We delineate the circuits responsible for these divergent effects, including signaling pathways. We review the unique effects of leptin during development on organogenesis, feeding behavior, and cardiorespiratory responses, and how undernutrition and overnutrition during critical periods of development can lead to cardiorespiratory comorbidities in adulthood. We conclude with suggestions for future directions to improve our understanding of leptin dysregulation and associated clinical diseases and possible therapeutic targets. Lastly, we briefly discuss the yin and the yang, specifically the contribution of relative adiponectin deficiency in adults with hyperleptinemia to the development of metabolic and cardiovascular disease. © 2020 American Physiological Society. Compr Physiol 10:1047-1083, 2020.

Metabolic regulation of hepatic PNPLA3 expression and severity of liver fibrosis in patients with NASH

BACKGROUND AND AIMS

The genetic PNPLA3 polymorphism I148M has been extensively associated with higher risk for development and progression of NAFLD towards NASH.

METHODS

PNPLA3 and α-SMA expression were quantified in liver biopsies collected from NASH patients (n = 26) with different fibrosis stages and PNPLA3 genotypes. To study the potential mechanisms driving PNPLA3 expression during NASH progression towards fibrosis, hepatocytes and hepatic stellate cells (HSCs) were cultivated in low and high glucose medium. Moreover, hepatocytes were treated with increasing concentrations of palmitic acid alone or in combination with glucose. Conditioned media were collected from challenged hepatocytes to stimulate HSCs.

RESULTS

Tissue expression of PNPLA3 was significantly enhanced in biopsies of patients carrying the I148M polymorphism compared to wild type (WT). In NASH biopsies, PNPLA3 significantly correlated with fibrosis stage and α-SMA levels independently of PNPLA3 genotype. In line, PNPLA3 expression was higher in α-SMA positive cells. Low glucose increased PNPLA3 in HSCs, whereas high glucose induced PNPLA3 and de-novo lipogenesis-related genes expression in hepatocytes. Palmitic acid induced fat accumulation and cell stress markers in hepatocytes, which could be counteracted by oleic acid. Conditioned media collected from lipotoxic challenged hepatocytes markedly induced PNPLA3 mRNA and protein levels, fibrogenic and autophagic markers and promoted migration in HSCs. Notably, conditioned media collected from hepatocytes cultivated with both glucose and palmitic acid exacerbated HSCs migration, PNPLA3 and fibrogenic gene expression, promoting release of cytokines from HSCs.

CONCLUSIONS

Collectively, our observations uncover the diverse metabolic regulation of PNPLA3 among different hepatic cell populations and support its relation to fibrosis progression.

The role of ADP-ribose metabolism in metabolic regulation, adipose tissue differentiation, and metabolism

In this review, Szanto et al. summarize the metabolic regulatory roles of PARP enzymes and their associated pathologies.

Poly(ADP-ribose) polymerases (PARPs or ARTDs), originally described as DNA repair factors, have metabolic regulatory roles. PARP1, PARP2, PARP7, PARP10, and PARP14 regulate central and peripheral carbohydrate and lipid metabolism and often channel pathological disruptive metabolic signals. PARP1 and PARP2 are crucial for adipocyte differentiation, including the commitment toward white, brown, or beige adipose tissue lineages, as well as the regulation of lipid accumulation. Through regulating adipocyte function and organismal energy balance, PARPs play a role in obesity and the consequences of obesity. These findings can be translated into humans, as evidenced by studies on identical twins and SNPs affecting PARP activity.

Role of Adiponectin in Cervical Cancer

BACKGROUND

Cervical Cancer (CC) is the most common leading cancer in women globally. This is considered to be the type of cancer that is restricted to women. Any women in the reproductive age range can develop CC. However, women between the ages of 25 and 39 are at a higher risk.

OBJECTIVE

In comparison with developed countries, the screening and awareness of CC in developing countries are significantly low. Infection with Human papillomavirus (HPV) is the main cause of CC, especially HPV-16 and HPV-18. Other than HPV, there are other factors that can contribute to CC, such as Human simplex virus (HSV) infection and immunocompromised patients with HIV.

CONCLUSION

Cervical cancer can be detected by molecular techniques such as (1) PCR, (2) visual acetic acid method, (3) DNA Hybrid II test, (4) liquid-based cytology, (5) Pap-Smear techniques, and (6) colposcopy techniques. Early detection of CC is very much needed; cryotherapy or LEEP (Loop electro surgical excision procedure) can be conducted during the pre-invasive stage of CC. Some metabolic changes in the human body such as fluctuating levels of insulin and triglycerides and increased activity of adiponectin may lead to CC. These contributing factors, such as adipokines, can be used as biomarkers for CC detection.

Screening and Identification of Differentially Expressed and Adipose Growth-Related Protein-Coding Genes During the Deposition of Perirenal Adipose Tissue in Rabbits

BACKGROUND

Rabbit is a good model for genetic and medical studies in other livestock species. The rabbit shows low adipose tissue deposition, and the phenomena indicates that there is some specificity of adipose deposition during the rabbit growth. However, little is known about genes that regulate the growth of adipose tissue in rabbits.

MATERIALS AND METHODS

Deep RNA-seq and comprehensive bioinformatics analyses were used to characterize the genes of rabbit visceral adipose tissue (VAT) at 35, 85 and 120 days after birth. Differentially expressed genes (DEGs) were identified at the three growth stages by DESeq. To explore the function of the candidate genes, Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed. Six DEGs were randomly selected, and their expression profiles were validated by q-PCR.

RESULTS

A total of 20,303 known transcripts and 99,199 new transcripts from 8 RNA sequencing libraries were identified, and 34 differentially expressed genes (DEGs) were screened. GO enrichment and KEGG pathway analyses revealed that the DEGs were mainly involved in lipid metabolism regulation including acylglycerol metabolic process and mobilization, and decomposition of lipids to generate ATP in adipocytes and fatty acid metabolism, included LOC100342322 and LOC100342572. In addition, 133 protein-coding genes that play a role in adipose growth and development were screened, including acyl-CoA synthetase long-chain family member 5 (ACSL5) and fatty acid-binding protein 2 (FABP2). The validation results of six DEGs by q-PCR showed similar trends with the results of RNA-seq.

CONCLUSION

In summary, this study provides the first report of the coding genes profiles of rabbit adipose tissue during different growth stages. These data allow for the identification of candidate genes for subsequent studies on rabbit genetics and regulation of adipose cells, and provide an animal model for studying obesity in humans.

Dihydropyranocoumarins Exerted Anti-Obesity Activity In Vivo and its Activity Was Enhanced by Nanoparticulation with Polylactic-Co-Glycolic Acid

Dihydropyranocoumarins (DPCs) were isolated from Peucedanum japonicum Thunb as anti-obesity compounds in 3T3-L1 adipocytes assay; however, it is uncertain whether DPC exerts anti-obesity activity in vivo. Therefore, this study evaluated the oral intake of pure DPCs in mice fed a high-fat diet, and also attempted to enhance its activity by nanoparticulation. Increases in body weight gain and fat accumulation in white adipose tissues were significantly suppressed by the dietary intake of DPCs (1.943 mg/mouse/day). DPCs intake also significantly decreased the mean size of adipocytes and upregulated mRNA levels of thermogenesis-related genes. Nanoparticulation of DPCs with polylactic-co-glycolic acid (PLGA) dramatically increased its activity almost 100-fold over that of a non-nanoparticulated form. Thus, our findings clearly demonstrated the anti-obesity activity of DPCs in vivo and suggested that PLGA nanoparticle encapsulation was useful to enhance the anti-obesity activity of DPCs with the aim to develop natural and safe anti-obesity agents.

Cardamonin suppresses lipogenesis by activating protein kinase A-mediated browning of 3T3-L1 cells

BACKGROUND

Obesity develops when dietary energy intake exceeds energy expenditure, and can be associated with metabolic syndrome. Recent studies have shown that dietary phytochemicals can promote energy expenditure by inducing the browning of white adipose tissue (WAT).

PURPOSE

This study investigated whether cardamonin induces the browning of 3T3-L1 adipocytes through the activation of protein kinase A (PKA).

METHODS

Anti-obesity potential of cardamonin was evaluated in 3T3-L1 adipocytes. Adipocyte-specific genes were observed using western blot, qPCR analysis and immunocytochemistry.

RESULTS

Cardamonin treatment inhibited lipid droplet accumulation and reduced the expression of the adipogenic proteins C/EBPα and FABP4, and the lipogenic proteins LPAATθ, lipin 1, DGAT1, SREBP1, and FAS. Cardamonin also induced the expression of the browning marker genes PRDM16, PGC1α, and UCP1 at the mRNA and protein levels, and induced mRNA expression of CD137, a key marker of beige adipocytes. It also increased the expression of the β-oxidation genes CPT1 and PPARα at the mRNA and protein levels. In addition, cardamonin increased PKA phosphorylation and the mRNA and protein expression of the downstream lipolytic enzymes adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL).

CONCLUSION

Our findings demonstrate novel effects of cardamonin to stimulate adipocyte browning, suppress lipogenesis, and promote lipolysis, implying it may have potential as an anti-obesity agent.

Current Progress on Peroxisome Proliferator-activated Receptor Gamma Agonist as an Emerging Therapeutic Approach for the Treatment of Alzheimer's Disease: An Update

Alzheimer's disease (AD) is an age-related progressive neurodegenerative disorder, characterized by the deposition of amyloid-β within the brain parenchyma resulting in a significant decline in cognitive functions. The pathophysiological conditions of the disease are recognized by the perturbation of synaptic function, energy and lipid metabolism. In Addition deposition of amyloid plaques also triggers inflammation upon the induction of microglia. Peroxisome proliferatoractivated receptors (PPARs) are ligand-activated transcription factors known to play important role in the regulation of glucose absorption, homeostasis of lipid metabolism and are further known to involved in repressing the expression of genes related to inflammation. Therefore, agonists of this receptor represent an attractive therapeutic target for AD. Recently, both clinical and preclinical studies showed that use of Peroxisome proliferator-activated receptor gamma (PPARγ) agonist improves both learning and memory along with other AD related pathology. Thus, PPARγ signifies a significant new therapeutic target in treating AD. In this review, we have shed some light on the recent progress of how, PPARγ agonist selectively modulated different cellular targets in AD and its amazing potential in the treatment of AD.

3,5-Dicaffeoyl-Epi-Quinic Acid Isolated from Edible Halophyte Atriplex gmelinii Inhibits Adipogenesis via AMPK/MAPK Pathway in 3T3-L1 Adipocytes

Atriplex gmelinii is an edible halophyte that has been suggested to possess various health benefits. In the present study, 3,5-dicaffeoyl-epi-quinic acid (DEQA) isolated from A. gmelinii was tested for its ability to prevent adipogenesis in 3T3-L1 cells. Also, the molecular mechanisms by which DEQA affects differentiation of 3T3-L1 cells were investigated. The introduction of DEQA to differentiating 3T3-L1 preadipocytes resulted in suppressed adipogenesis and lowered expression of adipogenesis-related factors, PPARγ, C/EBPα, and SREBP-1c. Treatment of 3T3-L1 adipocytes with DEQA notably decreased the levels of phosphorylated p38, ERK, and JNK. In addition, presence of DEQA upregulated the levels of both inactive and phosphorylated adenosine monophosphate-activated protein kinase (AMPK) and its substrate, acetyl-CoA carboxylase (ACC). Taken together, current results indicated that DEQA exhibited a significant antiadipogenesis activity by activation of AMPK and downregulation of MAPK signal pathways in 3T3-L1 preadipocytes.

Acrylamide induces adipocyte differentiation and obesity in mice

Obesity is a critical risk factor for various diseases including type II diabetes, cerebral infarction, cardiovascular diseases, and various cancers. Acrylamide (ACR) is present in wide range of foods, including fried potato products, root vegetables, bakery products, chips, cakes, cereals, and coffee. In this study, ACR treatment dramatically increased the accumulation of lipid droplets. We also examined expression levels of peroxisome proliferator-activated receptors γ (PPARγ), CCAAT enhancer binding protein α (c/EBPα), and CCAAT enhancer binding protein β (c/EBPβ) as adipogenic transcription factors for adipocyte differentiation. They were dose-dependently increased by treatment of ACR. Moreover, effects of ACR on mitogen-activated protein kinases (MAPKs) and 5' AMP-activated protein kinase (AMPK)-Acetyl-CoA carboxylase (ACC) activation were investigated. Results also showed that ACR induced phosphorylation of MAPKs and AMPK-ACC. ACR also induced expression of adipocyte fatty acid-binding protein (aP2), lipoprotein lipase (LPL), sterol regulatory element-binding protein (SREBP)-1c, and fatty acid synthase (FAS). Exposure of ACR to high fat diet (HFD)-fed mice significantly increased body weight, organ weight, and fat mass of mice. Collectively, these result showed that ACR can act as an enhancer of adipocyte. Therefore, we suggest that up-regulation of the adipogenesis by ACR may be related to the regulation of the MAPKs and AMPK-ACC pathway.

Anti-obesity Effect of Halophyte Crop, Limonium tetragonum in High-Fat Diet-Induced Obese Mice and 3T3-L1 Adipocytes

Halophyte Limonium tetragonum has recently been of interest in Korea for its nutritional value and salty taste which made it an ideal vegetable. In this study, the potential of L. tetragonum preventing excess weight gain, obesity and the related health problem has been evaluated in vitro and in vivo. The treatment with 100 mg/kg of L. tetragonum EtOAc soluble fraction (EALT) apparently prevented the body weight gain, adipose tissue weight gain, and the increase of triglyceride and total cholesterol level in mice fed a high-fat diet for 8 weeks. In addition, both glucose tolerance and insulin resistance in dietary obese mice were improved by EALT administration. A marked decrease in adipocyte differentiation was observed in the EALT (50 µg/mL)-treated 3T3-L1 cells, which was mediated by the suppression of adipogenesis-related transcription factors including peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer binding protein (C/EBP)α, and Sterol regulatory element binding protein-1 (SREBP-1) and adipocyte-specific proteins such as fatty acid synthase (FAS), lipoprotein lipase (LPL), and adipocyte fatty acid-binding protein (aP2). The major components contained in EALT were identified as (-)-epigallocatechin-3-(3″-O-methyl) gallate, (-)-epigallocatechin-3-gallate, and myricetin-3-O-β-D-galactopyranoside based on its phytochemical analysis. Results suggested that EALT might be available as functional crop and bioactive diet supplement for the prevention and/or treatment of obesity.

Citrus aurantium L. dry extracts promote C/ebpβ expression and improve adipocyte differentiation in 3T3-L1 cells

Metabolic and/or endocrine dysfunction of the white adipose tissue (WAT) contribute to the development of metabolic disorders, such as Type 2 Diabetes (T2D). Therefore, the identification of products able to improve adipose tissue function represents a valuable strategy for the prevention and/or treatment of T2D. In the current study, we investigated the potential effects of dry extracts obtained from Citrus aurantium L. fruit juice (CAde) on the regulation of 3T3-L1 cells adipocyte differentiation and function in vitro. We found that CAde enhances terminal adipocyte differentiation of 3T3-L1 cells raising the expression of CCAAT/enhancer binding protein beta (C/Ebpβ), peroxisome proliferator activated receptor gamma (Pparγ), glucose transporter type 4 (Glut4) and fatty acid binding protein 4 (Fabp4). CAde improves insulin-induced glucose uptake of 3T3-L1 adipocytes, as well. A focused analysis of the phases occurring in the pre-adipocytes differentiation to mature adipocytes furthermore revealed that CAde promotes the early differentiation stage by up-regulating C/ebpβ expression at 2, 4 and 8 h post the adipogenic induction and anticipating the 3T3-L1 cell cycle entry and progression during mitotic clonal expansion (MCE). These findings provide evidence that the exposure to CAde enhances in vitro fat cell differentiation of pre-adipocytes and functional capacity of mature adipocytes, and pave the way to the development of products derived from Citrus aurantium L. fruit juice, which may improve WAT functional capacity and may be effective for the prevention and/or treatment of T2D.

Differential effects of dietary flavonoids on adipogenesis

Propose

Obesity is a fast growing epidemic worldwide. During obesity, the increase in adipose tissue mass arise from two different mechanisms, namely, hyperplasia and hypertrophy. Hyperplasia which is the increase in adipocyte number is characteristic of severe obese patients. Recently, there has been much interest in targeting adipogenesis as therapeutic strategy against obesity. Flavonoids have been shown to regulate several pathways and affect a number of molecular targets during specific stages of adipocyte development.

Methods

Presently, we provide a review of key studies evaluating the effects of dietary flavonoids in different stages of adipocyte development with a particular emphasis on the investigations that explore the underlying mechanisms of action of these compounds in human or animal cell lines as well as animal models.

Results

Flavonoids have been shown to regulate several pathways and affect a number of molecular targets during specific stages of adipocyte development. Although most of the studies reveal anti-adipogenic effect of flavonoids, some flavonoids demonstrated proadipogenic effect in mesenchymal stem cells or preadipocytes.

Conclusion

The anti-adipogenic effect of flavonoids is mainly via their effect on regulation of several pathways such as induction of apoptosis, suppression of key adipogenic transcription factors, activation of AMPK and Wnt pathways, inhibition of clonal expansion, and cell-cycle arrest.

Screening of potential anti-adipogenic effects of phenolic compounds showing different chemical structure in 3T3-L1 preadipocytes

This study was designed to analyze the anti-adipogenic effect of fifteen phenolic compounds from various chemical groups in 3T3-L1 pre-adipocytes. Cells were treated with 25 μM, 10 μM or 1 μM of apigenin, luteolin, catechin, epicatechin, epigallocatechin, genistein, daizein, naringenin, hesperidin, quercetin, kaempferol, resveratrol, vanillic acid, piceatannol and pterostilbene for 8 days. At 25 μM lipid accumulation was reduced by all the compounds, with the exception of catechin, epicatechin and epigallocatechin. At a dose of 10 μM apigenin, luteolin, naringenin, hesperidin, quercetin and kaempferol induced significant reductions, and at 1 μM only naringenin, hesperidin and quercetin were effective. The expression of c/ebpα was not. C/ebpβ was significantly reduced by genistein and kaempferol, pparγ by genistein and pterostilbene, srebp1c by luteolin, genistein, hesperidin, kaempferol, pterostilbene and vanillic acid, and lpl by kaempferol. In conclusion, the most effective phenolic compounds are naringenin, hesperidin and quercetin. Differences were found in terms of effects on the expression of genes involved in adipogenesis among the analyzed compounds.

Anti-adipogenic effects of KD025 (SLx-2119), a ROCK2-specific inhibitor, in 3T3-L1 cells

Adipose tissue is a specialized organ that synthesizes and stores fat. During adipogenesis, Rho and Rho-associated kinase (ROCK) 2 are inactivated, which enhances the expression of pro-adipogenic genes and induces the loss of actin stress fibers. Furthermore, pan ROCK inhibitors enhance adipogenesis in 3T3-L1 cells. Here, we show that KD025 (formerly known as SLx-2119), a ROCK2-specific inhibitor, suppresses adipogenesis in 3T3-L1 cells partially through a ROCK2-independent mechanism. KD025 downregulated the expression of key adipogenic transcription factors PPARγ and C/EBPα during adipogenesis in addition to lipogenic factors FABP4 and Glut4. Interestingly, adipogenesis was blocked by KD025 during days 1~3 of differentiation; after differentiation terminated, lipid accumulation was unaffected. Clonal expansion occurred normally in KD025-treated cells. These results suggest that KD025 could function during the intermediate stage after clonal expansion. Data from depletion of ROCKs showed that KD025 suppressed cell differentiation partially independent of ROCK’s activity. Furthermore, no further loss of actin stress fibers emerged in KD025-treated cells during and after differentiation compared to control cells. These results indicate that in contrast to the pro-adipogenic effect of pan-inhibitors, KD025 suppresses adipogenesis in 3T3-L1 cells by regulating key pro-adipogenic factors. This outcome further implies that KD025 could be a potential anti-adipogenic/obesity agent.

Dietary docosahexaenoic acid decreased lipid accumulation via inducing adipocytes apoptosis of grass carp, Ctenopharygodon idella

The purpose of this study was to explore the mechanism of by which docosahexaenoic acid (DHA) inhibit the accumulation of adipose tissue lipid in grass carp (Ctenopharyngodon idella). We therefore designed two semi-purified diets, namely DHA-free (control) and DHA-supplemented, and fed them to grass carp (22.19 ± 1.76 g) for 3 and 6 weeks. DHA supplementation led to a significantly lower intraperitoneal fat index (IPFI) than that in the control group by reducing the number of adipocytes but significantly higher adipocyte size (P < 0.05). In the intraperitoneal adipose tissue, the DHA-fed group showed significantly higher peroxisome proliferator-activated receptor (PPAR)γ, CCAAT enhancer-binding protein (C/EBP)α, and sterol regulatory element-binding protein (SREBP)1c mRNA expression levels at both 3 and 6 weeks (P < 0.05). However, the ratio of the expression levels of B cell leukemia 2 (Bcl-2) and Bcl-2-associated X protein (Bax) was significantly lower in the DHA-fed group than in the control group (P < 0.05), and the protein expression levels of the apoptosis-related proteins caspase 3, caspase 8, and caspase 9 were also significantly higher (P < 0.05). Overall, although DHA promotes lipid synthesis, it is more likely that DHA could suppress the lipid accumulation in adipocytes of grass carp by inducing adipocyte apoptosis.

Prenatal Exposure to Endocrine Disruptors and Reprogramming of Adipogenesis: An Early-Life Risk Factor for Childhood Obesity

Obesity is a global health problem. It is characterized by excess adipose tissue that results from either increase in the number of adipocytes or increase in adipocytes size. Adipocyte differentiation is a highly regulated process that involves the activation of several transcription factors culminating in the removal of adipocytes from the cell cycle and induction of highly specific proteins. Several other factors, including hormones, genes, and epigenetics, are among the most important triggers of the differentiation process. Although the main contributing factors to obesity are high caloric intake, a sedentary lifestyle, and genetic predisposition, strong evidence supports a role for life exposure to environmental pollutants. Endocrine-disrupting chemicals are exogenous, both natural and man-made, chemicals that disrupt the body signaling processes, thus interfering with the endocrine system. Several studies have shown that prenatal exposure to endocrine disruptors modulates the mechanisms, by which multipotent mesenchymal stem cells differentiate into adipocytes. This review discusses adipocytes differentiation and highlights the possible mechanisms of prenatal exposure to endocrine disruptors in reprogramming of adipogenesis and induction of obesity later in life. Therefore, this review provides knowledge that reduction of early life exposure to these chemicals could open the door for new strategies in the prevention of obesity, especially during childhood.

Bee Venom Suppresses the Differentiation of Preadipocytes and High Fat Diet-Induced Obesity by Inhibiting Adipogenesis

Bee venom (BV) has been widely used in the treatment of certain immune-related diseases. It has been used for pain relief and in the treatment of chronic inflammatory diseases. Despite its extensive use, there is little documented evidence to demonstrate its medicinal utility against obesity. In this study, we demonstrated the inhibitory effects of BV on adipocyte differentiation in 3T3-L1 cells and on a high fat diet (HFD)-induced obesity mouse model through the inhibition of adipogenesis. BV inhibited lipid accumulation, visualized by Oil Red O staining, without cytotoxicity in the 3T3-L1 cells. Male C57BL/6 mice were fed either a HFD or a control diet for 8 weeks, and BV (0.1 mg/kg or 1 mg/kg) or saline was injected during the last 4 weeks. BV-treated mice showed a reduced body weight gain. BV was shown to inhibit adipogenesis by downregulating the expression of the transcription factors CCAAT/enhancer-binding proteins (C/EBPs) and the peroxisome proliferator-activated receptor gamma (PPARγ), using RT-qPCR and Western blotting. BV induced the phosphorylation of AMP-activated kinase (AMPK) and acetyl-CoA carboxylase (ACC) in the cell line and in obese mice. These findings demonstrate that BV mediates anti-obesity/differentiation effects by suppressing obesity-related transcription factors.

AQP3 is regulated by PPARγ and JNK in hepatic stellate cells carrying PNPLA3 I148M

Aquaglyceroporins (AQPs) allow the movement of glycerol that is required for triglyceride formation in hepatic stellate cells (HSC), as key cellular source of fibrogenesis in the liver. The genetic polymorphism I148M of the patatin-like phospholipase domain-containing 3 (PNPLA3) is associated with hepatic steatosis and its progression to steatohepatitis (NASH), fibrosis and cancer. We aimed to explore the role of AQP3 for HSC activation and unveil its potential interactions with PNPLA3. HSC were isolated from human liver, experiments were performed in primary HSC and human HSC line LX2. AQP3 was the only aquaglyceroporin present in HSC and its expression decreased during activation. The PPARγ agonist, rosiglitazone, recovered AQP3 expression also in PNPLA3 I148M carrying HSC. When PNPLA3 was silenced, AQP3 expression increased. In liver sections from patients with NASH, the decreased amount of AQP3 was proportional to the severity of fibrosis and presence of the PNPLA3 I148M variant. In PNPLA3 I148M cells, the blockade of JNK pathway upregulated AQP3 in synergism with PPARγ. In conclusion, we demonstrated profound reduction of AQP3 in HSC carrying the PNPLA3 I148M variant in parallel to decreased PPARγ activation, which could be rescued by rosiglitazone and blockade of JNK.

Potential miRNA involvement in the anti-adipogenic effect of resveratrol and its metabolites

OBJECTIVE

Scientific research is constantly striving to find molecules which are effective against excessive body fat and its associated complications. Taking into account the beneficial effects that resveratrol exerts on other pathologies through miRNA, the aim of the present work was to analyze the possible involvement of miRNAs in the regulation of adipogenic transcription factors peroxisome proliferator-activated receptor γ (pparγ), CCAAT enhancer-binding proteins α and β (cebpβ and cebpα) induced by resveratrol and its metabolites.

METHODS

3T3-L1 maturing pre-adipocytes were treated during differentiation with 25 μM of trans-resveratrol (RSV), trans-resveratrol-3-O-sulfate (3S), trans-resveratrol-3'-O-glucuronide (3G) and trans-resveratrol-4'-O-glucuronide (4G). After computational prediction and bibliographic search of miRNAs targeting pparγ, cebpβ and cebpα, the expression of microRNA-130b-3p (miR-130b-3p), microRNA-155-5p (miR-155-5p), microRNA-27b-3p (miR-27b-3p), microRNA-31-5p (miR-31-5p), microRNA-326-3p (miR-326-3p), microRNA-27a-3p (miR-27a-3p), microRNA-144-3p (miR-144-3p), microRNA-205-5p (miR-205-5p) and microRNA-224-3p (miR-224-3p) was analyzed. Moreover, other adipogenic mediators such as sterol regulatory element binding transcription factor 1 (srebf1), krüppel-like factor 5 (klf5), liver x receptor α (lxrα) and cAMP responding element binding protein 1 (creb1), were measured by Real Time RT-PCR. As a confirmatory assay, cells treated with RSV were transfected with anti-miR-155 in order to measure cebpβ gene and protein expressions.

RESULTS

Of the miRNAs analyzed only miR-155 was modified after resveratrol and glucuronide metabolite treatment. In transfected cells with anti-miR-155, RSV did not reduce cebpβ gene and protein expression. 3S decreased gene expression of creb1, klf5, srebf1 and lxrα.

CONCLUSIONS

While RSV and glucuronide metabolites exert their inhibitory effect on adipogenesis through miR-155 up-regulation, the anti-adipogenic effect of 3S is not mediated via miRNAs.

Fat Cell and Fatty Acid Turnover in Obesity

The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. Inhibition of adipose triglyceride lipase leads to an accumulation of triglyceride, whereas inhibition of hormone-sensitive lipase leads to the accumulation of diacylglycerol. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride turnover. Excess triacylglycerols (TAGs), sterols and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets. Following the release of lipid droplets from endoplasmic reticulum, cytoplasmic lipid droplets increase their volume either by local TAG synthesis or by homotypic fusion. The number and the size of lipid droplet distribution is correlated with obesity. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. NOD-like receptors family pyrin domain containing 3 (NLRP3) inflammasome-dependent caspase-1 activation in hypertrophic adipocytes induces obese adipocyte death by pyroptosis. Actually adipocyte death may be a prerequisite for the transition from hypertrophic to hyperplastic obesity. Major transcriptional factors, CCAAT/enhancer-binding proteins beta and delta, play a central role in the subsequent induction of critical regulators, peroxisome-proliferator-activated receptor gamma, CCAAT/enhancer-binding protein alpha and sterol regulatory element-binding protein 1, in the transcriptional control of adipogenesis in obesity.Collectively, in this chapter the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of lipid droplet interactions with the other cellular organelles are reviewed. Furthermore, in addition to lipid droplet growth, the functional link between the adipocyte-specific lipid droplet-associated protein and fatty acid turn-over is also debated.

Lamins and metabolism

Lamins are nuclear intermediate filaments (IFs) with important roles in most nuclear activities, including nuclear organization and cell-cycle progression. Mutations in human lamins cause over 17 different diseases, termed laminopathies. Most of these diseases are autosomal dominant and can be roughly divided into four major groups: muscle diseases, peripheral neuronal diseases, accelerated aging disorders and metabolic diseases including Dunnigan type familial partial lipodystrophy (FLPD), acquired partial lipodystrophy (APL) and autosomal dominant leucodystrophy. Mutations in lamins are also associated with the metabolic syndrome (MS). Cells derived from patients suffering from metabolic laminopathies, as well as cells derived from the corresponding animal models, show a disruption of the mechanistic target of rapamycin (mTOR) pathway, abnormal autophagy, altered proliferative rate and down-regulation of genes that regulate adipogenesis. In addition, treating Hutchinson-Gilford progeria syndrome (HGPS) cells with the mTOR inhibitor rapamycin improves their fate. In this review, we will discuss the ways by which lamin genes are involved in the regulation of cell metabolism.

WISP1/CCN4 inhibits adipocyte differentiation through repression of PPARγ activity

WISP1 (Wnt1-inducible signaling pathway protein-1, also known as CCN4) is a member of the CCN family able to mediate cell growth, transformation and survival in a tissue-specific manner. Here, we report that WISP1 expression was highly increased in preadipocytes and decreased during adipocyte differentiation. Moreover, we observed an increase in WISP1 gene expression in adipose tissue from both diet-induced and leptin-deficient ob/ob obese mice, suggesting that WISP1 could be involved in the pathophysiological onset of obesity. Interestingly, overexpression of WISP1 in 3T3-F442A cells prevented adipocyte differentiation via downregulation of peroxisome proliferator-activated receptor (PPARγ) transcriptional activity thereby attenuating the expression of adipogenic markers. Conversely, silencing of WISP1 enhanced adipocyte differentiation. We further show that the inactivation of PPARγ transcriptional activity was mediated, at least in part, by a direct physical association between WISP1 and PPARγ, followed by proteasome-dependent degradation of PPARγ. These results suggest for the first time that WISP1 interacts with PPARγ and that this interaction results in the inhibition of PPARγ activity. Taken together our results suggest that WISP1 functions as a negative regulator of adipogenesis.

The therapeutic landscape of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by lobular inflammation and hepatocellular ballooning, and may be associated with liver fibrosis leading to cirrhosis and its complications. A pharmacological approach is necessary to treat NASH because of failure to change dietary habits and lifestyle in most patients. Insulin resistance with an increased release of free fatty acids, oxidative stress and activation of inflammatory cytokines seem to be key features for disease progression. Thiazolidinediones, such as pioglitazone and antioxidant agents, such as vitamin E, were the first pharmacological options to be evaluated for NASH. In recent years, several new molecules that target different pathways related to NASH pathogenesis, such as liver metabolic homeostasis, inflammation, oxidative stress and fibrosis, have been developed. Obeticholic acid (INT-747) and elafibranor (GFT-505) have provided promising results in phase IIb, randomized, placebo-controlled clinical trials and they are being evaluated in ongoing phase III studies. Most of the potential treatments for NASH are under investigation in phase II studies, with some at phase I. This diversity in possible treatments calls for a better understanding of NASH in order to enrich trial populations with patients more susceptible to progress and to respond. This manuscript aims to review the pharmacological NASH treatment landscape.

3,3'-Diindolylmethane Suppresses Adipogenesis Using AMPKα-Dependent Mechanism in 3T3-L1 Adipocytes and Caenorhabditis elegans

3,3'-diindolylmethane is a major in vivo metabolite of indole-3-carbinol, a bioactive compound found in cruciferous vegetables. Although 3,3'-diindolylmethane has been implicated to possess antitumorigenic and anti-inflammatory properties, the effect of 3,3'-diindolylmethane on adipogenesis has not been explored previously. Thus, the present study was conducted to determine if 3,3'-diindolylmethane affects adipogenesis using 3T3-L1 adipocytes and Caenorhabditis elegans. Treatment of 3,3'-diindolylmethane significantly reduced fat accumulation without affecting viability in 3T3-L1 adipocytes. 3,3'-diindolylmethane suppressed expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT-enhancer-binding protein α (C/EBPα), fatty acid binding protein 4 (FABP4), and perilipin. In addition, 3,3'-diindolylmethane activated AMP-activated protein kinase α (AMPKα), which subsequently inactivated acetyl CoA carboxylase (ACC), resulting in reduced fat accumulation. These observations were further confirmed in C. elegans as treatment with 3,3'-diindolylmethane significantly reduced body fat accumulation, which was partly associated with aak-1, but not aak-2, orthologs of AMPKα catalytic subunits α1 and α2, respectively. The current results demonstrate that 3,3'-diindolylmethane, a biologically active metabolite of indole-3-carbinol, may prevent adipogenesis through the AMPKα-dependent pathway.

miR-26a Mediates Adipogenesis of Amniotic Fluid Mesenchymal Stem/Stromal Cells via PTEN, Cyclin E1, and CDK6

Recent findings indicate that microRNAs (miRNAs) are critical for the regulatory network of adipogenesis in human mesenchymal stem/stromal cells (MSCs). Fetal MSCs derived from amniotic fluid (AF-MSCs) represent a population of multipotent stem cells characterized by a wide range of differentiation properties that can be applied in cell-based therapies. In this study, miRNA microarray analysis was performed to assess miRNA expression in terminal differentiated AF-MSCs into adipocyte-like cells (AL cells). MiR-26a was identified in high expression levels in AL cells indicating a critical role in the process of adipogenesis. Overexpression of miR-26a in AF-MSCs led to significant induction of their adipogenic differentiation properties that were altered after miR-26a inhibition. We have demonstrated that miR-26a regulates adipogenesis through direct inhibition of PTEN, which in turn promotes activation of Akt pathway. Also, miR-26a modulates cell cycle during adipogenesis by interacting with Cyclin E1 and CDK6. These results point to the regulatory role of miR-26a and its target genes PTEN, Cyclin E1, and CDK6 in adipogenic differentiation of AF-MSCs, providing a basis for understanding the mechanisms of fat cell development and obesity.

Adipose Tissue Hypoxia in Obesity and Its Impact on Preadipocytes and Macrophages: Hypoxia Hypothesis

Obese subjects exhibit lower adipose tissue oxygen consumption in accordance with the lower adipose tissue blood flow. Thus, compared with lean subjects, obese subjects have 44% lower capillary density and 58% lower vascular endothelial growth factor (VEGF). The VEGF expression together with hypoxia-inducible transcription factor-1 (HIF-1) activity also requires phosphatidylinositol 3-kinase (PI3K)- and target of rapamycin (TOR)-mediated signaling. HIF-1alpha is an important signaling molecule for hypoxia to induce the inflammatory responses. Hypoxia affects a number of biological functions, such as angiogenesis, cell proliferation, apoptosis, inflammation and insulin resistance. Additionally, reactive oxygen radical (ROS) generation at mitochondria is responsible for propagation of the hypoxic signal. Actually mitochondrial ROS (mtROS) production, but not oxygen consumption is required for hypoxic HIF-1alpha protein stabilization. Adipocyte mitochondrial oxidative capacity is reduced in obese compared with non-obese adults. In this respect, mitochondrial dysfunction of adipocyte is associated with the overall adiposity. Furthermore, hypoxia also inhibits macrophage migration from the hypoxic adipose tissue. Alterations in oxygen availability of adipose tissue directly affect the macrophage polarization and are responsible from dysregulated adipocytokines production in obesity. Hypoxia also inhibits adipocyte differentiation from preadipocytes. In addition to stressed adipocytes, hypoxia contributes to immune cell immigration and activation which further aggravates adipose tissue fibrosis. Fibrosis is initiated in response to adipocyte hypertrophy in obesity.

CXCL3 positively regulates adipogenic differentiation

Chemokines are a family of cytokines inducing cell migration and inflammation. Recent reports have implicated the roles of chemokines in cell differentiation. However, little is known about the functional roles of chemokines in adipocytes. Here, we explored gene expression levels of chemokines and chemokine receptors during adipogenic differentiation. We have found that two chemokines, chemokine (C-X-C motif) ligand 3 (CXCL3) and CXCL13, as well as CXC chemokine receptor 2 (CXCR2), a CXCL3 receptor, are highly expressed in mature adipocytes. When 3T3-L1 cells and ST2 cells were induced to differentiate, both the number of lipid droplets and the expression levels of adipogenic markers were significantly promoted by the addition of CXCL3, but not CXCL13. Conversely, gene knockdown of either CXCL3 or CXCR2 by specific siRNA effectively inhibited the course of adipogenic differentiation. CXCL3 treatment of 3T3-L1 cells significantly induced the phosphorylation of ERK and c-jun N-terminal kinase (JNK). Furthermore, CXCL3-induced CCAAT-enhancer binding protein (C/EBP)β and δ expression was suppressed by both ERK and JNK-specific inhibitors. Furthermore, chromatin immunoprecipitation assay revealed functional binding of PPARγ2 within the cxcl3 promoter region. Taken together, these results have indicated that CXCL3 is a novel adipokine that facilitates adipogenesis in an autocrine and/or a paracrine manner through induction of c/ebpb and c/ebpd.