Interaction between GATA and the C/EBP family of transcription factors is critical in GATA-mediated suppression of adipocyte differentiation

DPP-IV and FAS inhibitory peptides: therapeutic alternative against diabesity

Diabesity is a modern epidemic that indicates a strong association between obesity and diabetes. Key enzymes have been identified in the development and progression of both diseases, DPP-IV in glucose uptake and FAS in fatty acid synthesis. In both cases, the molecular mechanisms of how each one acts separately have been described, and which are the key inhibitory drugs and molecules for each one. However, although it is known that there is an association between both clinically and molecularly, the mechanism has not been elucidated; therefore, this review focuses on proposing a mechanism of convergence of DPP-IV and FAS in diabesity, and the possible mode of action in which bioactive peptides obtained from plant and animal sources can inhibit these two enzymes in a similar way as drugs do.

Growth hormone regulates deiodinase type 2 and 3 expression via GATA

OBJECTIVE

Growth hormone (GH) is involved in bone and skeletal muscle growth directly or indirectly via STAT5 and/or insulin-like growth factor (IGF)-1. Thyroid hormone (TH) is essential for general cellular growth and metabolic regulation. While both GH and TH are essential for growth, their actions may partially complement each other in conditions of hormonal deficiency. For example, TH can enhance GH secretion and sensitivity, while GH is ineffective in Refetoff syndrome due to TH receptor dysfunction. However, the underlying molecular mechanism remains unclear. In this study, we investigated the molecular mechanisms underlying the complementarity between GH and TH, paying special attention to the effects of GH on the expression of both iodothyronine deiodinase (DIO) type 2 (DIO2) and type 3 (DIO3).

DESIGN

The effects of growth hormone (GH) on DIOs were examined using reporter assays, chromatin immunoprecipitation, quantitative PCR, and western blotting using HEK293-derived TSA201 cells and mouse ATDC5 chondrocytes.

RESULTS

GH induced the mRNA and protein expression of DIOs in ATDC5 cells via STAT5/GATA. GATAs activate the promoter activity of both DIOs. The binding sites for GATA on the DIO promoter were located -87 bp and - 75 bp upstream from the TSS for the DIO2 promoter and - 6 bp upstream from the TSS for the DIO3 promoter, respectively. GH-induced expression of DIOs in ATDC5 cells was abolished by K-7174, a GATA-specific inhibitor.

CONCLUSION

The present study demonstrates that GH regulates DIO2 and DIO3 expression via JAK/STAT5/GATAs after binding to GHR. This is the first report on the molecular mechanisms underlying GH-dependent compensation of TH action. (256 words).

Design, synthesis, and biological evaluation of novel quinoline carboxylic acid based styryl/alkyne hybrid molecule as a potent anti-adipogenic and antidyslipidemic agent via activation of Wnt/β-catenin pathway

Obesity has emerged as the root cause for various metabolic disorders worldwide and hence demands for urgent attention. In the same stride, a series of quinoline carboxylic acid-based styryl/alkyne hybrids were designed, synthesized, and evaluated for their anti-adipogenic activity. Based on the structure-activity relationship, functional groups and essential substituents to potentiate the anti-adipogenic activity were identified. The potent compound (E)-6-fluoro-2-(4-(4-methylstyryl)phenyl)quinoline-4-carboxylic acid (5m) suppresses the adipogenesis with IC50 value of 0.330 μM. In vitro studies in 3T3-L1 preadipocytes cell line show that compound 5m prevents adipogenesis by stopping the cell cycle at the early phase of differentiation, which is caused by stimulation of the Wnt3a/β-catenin pathway. Further compound 5m improves the blood lipid profile and reduces adipogenic marker proteins in the epididymal white adipose tissue (eWAT) of dyslipidemic hamster at 100 mg/kg/day oral dose. Treatment with compound 5m reduces the hypertrophied adipose tissue along with the decrease in the levels of adipogenic marker proteins such as PPARγ and CEBPα. The pharmacokinetic result establishes the molecule 5m to be stable with significant oral bioavailability. Henceforth, the present study provides a unique insight into the anti-adipogenic/anti-dyslipidemic properties of a novel styryl-quinoline carboxylic acid scaffold with a scope to enhance the anti-adipogenic potency for therapeutic intervention of obesity.

GATA3: Orchestrating cellular fate through differentiation and proliferation

Cell proliferation and differentiation are two fundamental biological processes that occur in biological systems, tightly regulated by various factors such as transcription factors (TFs). Zinc finger proteins are TFs responsible for maintaining the biological balance via coordinating development and functionality within the living cells. GATA binding protein 3 (GATA3), one of the zinc finger proteins, plays an essential role in driving differentiation and proliferation-related processes, thereby contributing to the regulation of the dynamism and productivity of living cells. By elucidating the complex interactions governed by GATA3, this underscores its significance in maintaining cellular homeostasis. Thus, the current review delves into the molecular pathways influenced by GATA3, highlighting its involvement in multiple developmental processes of various tissues and body sites, particularly in the hematopoietic system (T-cell differentiation), neural tissue differentiation, adipose tissue, as well as epithelial cell maturation.

Targeted Inhibition of GATA-3 by Pyrrothiogatain: Implications for Adipocyte Biology and Inflammatory Response

GATA-3 is a master regulator of preadipocyte differentiation and function. Pharmacological or genetic targeting of GATA-3 will allow us to understand the function of GATA-3 in regulating metabolism, insulin signaling, and inflammation. Pyrrothiogatain, a novel small molecule inhibitor of GATA family proteins, has emerged as a promising tool for modulating GATA-3 activity. This study aims to investigate the specificity of Pyrrothiogatain in regulating GATA-3-mediated preadipocyte differentiation and adipokine secretion under normal and pathological conditions. Wild-type and GATA-3 knockout 3T3-L1 cells were treated with different concentrations of Pyrrothiogatain in the presence and absence of 4-hydroxy-2-nonenal (4HNE), an inducer of oxidative stress and impairment of adipogenesis. As expected, GATA-3 knockout cells exhibited enhanced adipogenic capacity, characterized by increased cell and lipid droplet sizes, and upregulated expression of key adipogenic markers including CEBPβ, PPARγ, and PGC-1α. Pyrrothiogatain treatment reduced cell proliferation in both wild-type and GATA-3 knockout 3T3-L1 cells, but did not alter their adipogenic capacity. Furthermore, Pyrrothiogatain lowered secreted IL-6 levels and attenuated 4-HNE-induced TNF-α elevation in wild-type, but not in GATA-3 knockout cells. Co-treatment of 4-HNE and Pyrrothiogatain led to increased cell size, suggesting complex interactions between oxidative stress and GATA protein inhibition. This effect was similar to GATA-3 knockout cells, indicating Pyrrothiogatain's potential to modulate cellular stress responses independently of GATA-3 inhibition. These results reveal that Pyrrothiogatain's effects on adipocyte biology extend beyond simple GATA-3 inhibition. While GATA-3 knockout primarily affects adipogenesis, Pyrrothiogatain modulates inflammatory responses and potentially cellular stress mechanisms without directly impacting adipocyte differentiation. This study provides new insights into the multifaceted actions of Pyrrothiogatain and highlights its potential as a therapeutic agent for lowering inflammation and oxidative-stress-related aspects of metabolic disorders, distinct from the direct modulation of adipogenesis.

Unveiling GATA3 Signaling Pathways in Health and Disease: Mechanisms, Implications, and Therapeutic Potential

GATA binding protein 3 (GATA3), a member of the GATA family transcription factors, is a key player in various physiological and pathological conditions. It is known for its ability to bind to the DNA sequence "GATA", which enables its key role in critical processes in multiple tissues and organs including the immune system, endocrine system, and nervous system. GATA3 also modulates cell differentiation, proliferation, and apoptosis via controlling gene expression. In physiological instances, GATA3 is crucial for maintaining immunological homeostasis by mediating the development of naïve T cells into T helper 2 (Th2). In addition, GATA3 has been demonstrated to play a variety of cellular roles in the growth and maintenance of mammary gland, neuronal, and renal tissues. Conversely, the presence of impaired GATA3 is associated with a variety of diseases, including neurodegenerative diseases, autoimmune diseases, and cancers. Additionally, the altered expression of GATA3 contributes to the worsening of disease progression in hematological malignancies, such as T-cell lymphomas. Therefore, this review explores the multifaceted roles and signaling pathways of GATA3 in health and disease, with a particular emphasis on its potential as a therapeutic and prognostic target for the effective management of diseases.

Novel insights into regulators and functional modulators of adipogenesis

Adipogenesis is a process that differentiates new adipocytes from precursor cells and is tightly regulated by several factors, including many transcription factors and various post-translational modifications. Recently, new roles of adipogenesis have been suggested in various diseases. However, the molecular mechanisms and functional modulation of these adipogenic genes remain poorly understood. This review summarizes the regulatory factors and modulators of adipogenesis and discusses future research directions to identify novel mechanisms regulating adipogenesis and the effects of adipogenic regulators in pathological conditions. The master adipogenic transcriptional factors PPARγ and C/EBPα were identified along with other crucial regulatory factors such as SREBP, Kroxs, STAT5, Wnt, FOXO1, SWI/SNF, KLFs, and PARPs. These transcriptional factors regulate adipogenesis through specific mechanisms, depending on the adipogenic stage. However, further studies related to the in vivo role of newly discovered adipogenic regulators and their function in various diseases are needed to develop new potent therapeutic strategies for metabolic diseases and cancer.

Comparative analysis of diisononyl phthalate and di(isononyl)cyclohexane-1,2 dicarboxylate plasticizers in regulation of lipid metabolism in 3T3-L1 cells

Diisononyl phthalate (DINP) and di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) are plasticizers introduced to replace previously used phthalate plasticizers in polymeric products. Exposure to DINP and DINCH has been shown to impact lipid metabolism. However, there are limited studies that address the mechanisms of toxicity of these two plasticizers. Here, a comparative toxicity analysis has been performed to evaluate the impacts of DINP and DINCH on 3T3-L1 cells. The preadipocyte 3T3-L1 cells were exposed to 1, 10, and 100 μM of DINP or DINCH for 10 days and assessed for lipid accumulation, gene expression, and protein analysis. Lipid staining showed that higher concentrations of DINP and DINCH can induce adipogenesis. The gene expression analysis demonstrated that both DINP and DINCH could alter the expression of lipid-related genes involved in adipogenesis. DINP and DINCH upregulated Pparγ, Pparα, C/EBPα Fabp4, and Fabp5, while both compounds significantly downregulated Fasn and Gata2. Protein analysis showed that both DINP and DINCH repressed the expression of FASN. Additionally, we analyzed an independent transcriptome dataset encompassing temporal data on lipid differentiation within 3T3-L1 cells. Subsequently, we derived a gene set that accurately portrays significant pathways involved in lipid differentiation, which we subsequently subjected to experimental validation through quantitative polymerase chain reaction. In addition, we extended our analysis to encompass a thorough assessment of the expression profiles of this identical gene set across 40 discrete transcriptome datasets that have linked to diverse pathological conditions to foreseen any potential association with DINP and DINCH exposure. Comparative analysis indicated that DINP could be more effective in regulating lipid metabolism.

The optimized priming effect of FGF-1 and FGF-2 enhances preadipocyte lineage commitment in human adipose-derived mesenchymal stem cells

The cell-assisted lipotransfer technique, integrating adipose-derived mesenchymal stem cells (ADMSCs), has transformed lipofilling, enhancing fat graft viability. However, the multipotent nature of ADMSCs poses challenges. To improve safety and graft vitality and to reduce unwanted lineage differentiation, this study refines the methodology by priming ADMSCs into preadipocytes-unipotent, self-renewing cells. We explored the impact of fibroblast growth factor-1 (FGF-1), fibroblast growth factor-2 (FGF-2), and epidermal growth factor (EGF), either alone or in combination, on primary human ADMSCs during the proliferative phase. FGF-2 emerged as a robust stimulator of cell proliferation, preserving stemness markers, especially when combined with EGF. Conversely, FGF-1, while not significantly affecting cell growth, influenced cell morphology, transitioning cells to a rounded shape with reduced CD34 expression. Furthermore, co-priming with FGF-1 and FGF-2 enhanced adipogenic potential, limiting osteogenic and chondrogenic tendencies, and possibly promoting preadipocyte commitment. These preadipocytes exhibited unique features: rounded morphology, reduced CD34, decreased preadipocyte factor 1 (Pref-1), and elevated C/EBPα and PPARγ, alongside sustained stemness markers (CD73, CD90, CD105). Mechanistically, FGF-1 and FGF-2 activated key adipogenic transcription factors-C/EBPα and PPARγ-while inhibiting GATA3 and Notch3, which are adipogenesis inhibitors. These findings hold the potential to advance innovative strategies for ADMSC-mediated lipofilling procedures.

Clinically Effective Molecules of Natural Origin for Obesity Prevention or Treatment

The prevalence and incidence of obesity and the comorbidities linked to it are increasing worldwide. Current therapies for obesity and associated pathologies have proven to cause a broad number of adverse effects, and often, they are overpriced or not affordable for all patients. Among the alternatives currently available, natural bioactive compounds stand out. These are frequently contained in pharmaceutical presentations, nutraceutical products, supplements, or functional foods. The clinical evidence for these molecules is increasingly solid, among which epigallocatechin-3-gallate, ellagic acid, resveratrol, berberine, anthocyanins, probiotics, carotenoids, curcumin, silymarin, hydroxy citric acid, and α-lipoic acid stand out. The molecular mechanisms and signaling pathways of these molecules have been shown to interact with the endocrine, nervous, and gastroenteric systems. They can regulate the expression of multiple genes and proteins involved in starvation-satiety processes, activate the brown adipose tissue, decrease lipogenesis and inflammation, increase lipolysis, and improve insulin sensitivity. This review provides a comprehensive view of nature-based therapeutic options to address the increasing prevalence of obesity. It offers a valuable perspective for future research and subsequent clinical practice, addressing everything from the molecular, genetic, and physiological bases to the clinical study of bioactive compounds.

The role of zinc finger proteins in the fate determination of mesenchymal stem cells during osteogenic and adipogenic differentiation

Zinc finger proteins (ZFPs) constitute a crucial group of transcription factors widely present in various organisms. They act as transcription factors, nucleases, and RNA-binding proteins, playing significant roles in cell differentiation, growth, and development. With extensive research on ZFPs, their roles in the determination of mesenchymal stem cells (MSCs) fate during osteogenic and adipogenic differentiation processes have become increasingly clear. ZFP521, for instance, is identified as an inhibitor of the Wnt signaling pathway and RUNX2's transcriptional activity, effectively suppressing osteogenic differentiation. Moreover, ZFP217 contributes to the inhibition of adipogenic differentiation by reducing the M6A level of the cell cycle regulator cyclin D1 (CCND1). In addition, other ZFPs can also influence the fate of mesenchymal stem cells (MSCs) during osteogenic and adipogenic differentiation through various signaling pathways, transcription factors, and epigenetic controls, participating in the subsequent differentiation and maturation of precursor cells. Given the prevalent occurrence of osteoporosis, obesity, and related metabolic disorders, a comprehensive understanding of the regulatory mechanisms balancing bone and fat metabolism is essential, with a particular focus on the fate determination of MSCs in osteogenic and adipogenic differentiation. In this review, we provide a detailed summary of how zinc finger proteins influence the osteogenic and adipogenic differentiation of MSCs through different signaling pathways, transcription factors, and epigenetic mechanisms. Additionally, we outline the regulatory mechanisms of ZFPs in controlling osteogenic and adipogenic differentiation based on various stages of MSC differentiation.

Surface-exposed chaperonin 60 derived from Propionibacterium freudenreichii MJ2 inhibits adipogenesis by decreasing the expression of C/EBPα/PPARγ

Recent studies have shown that the health benefits of probiotics are not limited to those offered by living bacteria. It was reported that both live and killed cells of Propionibacterium freudenreichii MJ2 (MJ2) isolated from raw milk showed antiobesity activity in 3T3-L1 cells and high-fat diet-induced obese mice. This study was aimed at identifying the active component(s) responsible for the antiadipogenic activity of MJ2. Cell wall, surface protein, and cytoplasmic fractions of MJ2 were investigated for their inhibitory effects on adipogenesis in 3T3-L1 cells. Adipocytes treated with the surface protein fraction showed significantly lower lipid accumulation. Using the MASCOT algorithm following LC-MS/MS analysis, 131 surface proteins were identified and they were principally classified into three categories (network clusters related to ribosomes, carbon metabolism, and chaperones). Among them, chaperonin 60 (Cpn60) was selected as a potential candidate protein. Cpn60 inhibited lipid accumulation and adipogenesis during the early period of differentiation (days 0-2) and decreased expression of genes related to adipogenesis (Pparg and Cebpa) and lipogenesis (Fas and Scd1). The expression of Gata2/3, which suppresses adipogenesis, significantly increased in Cpn60-treated cells. Moreover, the nuclear translocation of C/EBPβ was inhibited by Cpn60 treatment. In conclusion, Cpn60, a surface protein in MJ2, shows antiadipogenic activity by reducing the expression of C/EBPβ through the upregulation of Gata2/3 expression followed by downregulation of Pparg and Cebpa expression.

Role of the pioneer transcription factor GATA2 in health and disease

The transcription factor GATA2 is involved in human diseases ranging from hematopoietic disorders, to cancer, to infectious diseases. GATA2 is one of six GATA-family transcription factors that act as pioneering transcription factors which facilitate the opening of heterochromatin and the subsequent binding of other transcription factors to induce gene expression from previously inaccessible regions of the genome. Although GATA2 is essential for hematopoiesis and lymphangiogenesis, it is also expressed in other tissues such as the lung, prostate gland, gastrointestinal tract, central nervous system, placenta, fetal liver, and fetal heart. Gene or transcriptional abnormalities of GATA2 causes or predisposes patients to several diseases including the hematological cancers acute myeloid leukemia and acute lymphoblastic leukemia, the primary immunodeficiency MonoMAC syndrome, and to cancers of the lung, prostate, uterus, kidney, breast, gastric tract, and ovaries. Recent data has also linked GATA2 expression and mutations to responses to infectious diseases including SARS-CoV-2 and Pneumocystis carinii pneumonia, and to inflammatory disorders such as atherosclerosis. In this article we review the role of GATA2 in the etiology and progression of these various diseases.

Acidosis-induced regulation of adipocyte G0S2 promotes crosstalk between adipocytes and breast cancer cells as well as tumor progression

Bidirectional interactions between cancer cells and their microenvironment govern tumor progression. Among the stromal cells in this microenvironment, adipocytes have been reported to upregulate cancer cell migration and invasion by producing fatty acids. Conversely, cancer cells alter adipocyte phenotype notably via increased lipolysis. We aimed to identify the mechanisms through which cancer cells trigger adipocyte lipolysis and evaluate the functional consequences on cancer progression. Here, we show that cancer cell-induced acidification of the extracellular medium strongly promotes preadipocyte lipolysis through a mechanism that does not involve lipophagy but requires adipose triglyceride lipase (ATGL) activity. This increased lipolysis is triggered mainly by attenuation of the G0/G1 switch gene 2 (G0S2)-induced inhibition of ATGL. G0S2-mediated regulation in preadipocytes affects their communication with breast cancer cells, modifying the phenotype of the cancer cells and increasing their resistance to chemotherapeutic agents in vitro. Furthermore, we demonstrate that the adipocyte-specific overexpression of G0S2 impairs mammary tumor growth and lung metastasis formation in vivo. Our results highlight the importance of acidosis in cancer cell-adipocyte crosstalk and identify G0S2 as the main regulator of cancer-induced lipolysis, regulating tumor establishment and spreading.

A novel candidate gene CLN8 regulates fat deposition in avian

BACKGROUND

The fat deposition has a crucial role in animal meat flavor, and fat deposition-related traits are vital for breeding in the commercial duck industry. Avian fat-related traits are typical complex phenotypes, which need a large amount of data to analyze the genetic loci.

RESULTS

In this study, we performed a new phenotypic analysis of fat traits and genotyped whole-genome variations for 1,246 ducks, and combed with previous GWAS data to reach 1,880 ducks for following analysis. The carcass composition traits, subcutaneous fat weight (SFW), subcutaneous fat percentage (SFP), abdominal fat weight (AFW), abdominal fat percentage (AFP) and the body weight of day 42 (BW42) for each duck were collected. We identified a set of new loci that affect the traits related to fat deposition in avian. Among these loci, ceroid-lipofuscinosis, neuronal 8 (CLN8) is a novel candidate gene controlling fat deposition. We investigated its novel function and regulation in avian adipogenesis. Five significant SNPs (the most significant SNP, P-value = 21.37E-12) and a single haplotype were detected in the upstream of CLN8 for subcutaneous fat percentage. Subsequently, luciferase assay demonstrated that 5 linked SNPs in the upstream of the CLN8 gene significantly decreased the transcriptional activity of CLN8. Further, ATAC-seq analysis showed that transcription factor binding sites were identified in a region close to the haplotype. A set of luciferase reporter gene vectors that contained different deletion fragments of the CLN8 promoter were constructed, and the core promoter area of CLN8 was finally identified in the -1,884/-1,207 bp region of the 5' flanking sequences, which contains adipogenesis-related transcription factors binding sites. Moreover, the over-expression of CLN8 can remarkably facilitate adipocyte differentiation in ICPs. Consistent with these, the global transcriptome profiling and functional analysis of the over-expressed CLN8 in the cell line further revealed that the lipid biosynthetic process during the adipogenesis was significantly enriched.

CONCLUSIONS

Our results demonstrated that CLN8 is a positive regulator of avian adipocyte differentiation. These findings identify a novel function of CLN8 in adipocyte differentiation, which provides important clues for the further study of the mechanism of avian fat deposition.

Zinc finger protein 251 deficiency impairs glucose metabolism by inducing adipocyte hypertrophy

Zinc finger protein (ZFP) 251 is a member of the C2H2 ZFP family containing a Krüppel-associated box domain that might mainly act as a transcriptional repressor. However, its cellular function remains largely unknown. Here, we discovered that ZFP251 deficiency caused glucose intolerance in mice. This phenotype was associated with impaired insulin signaling due to hypertrophic changes in white adipose tissue (WAT). Gene ontology analysis revealed that ZFP251 deficiency affected the expression of genes associated with adipocyte differentiation and lipid and fatty acid metabolism. Consistent with in vivo results, hypertrophic changes were observed in Zfp251 knockdown (KD) 3T3-L1 adipocytes. In addition, Zfp251 KD 3T3-L1 preadipocytes exhibited cell cycle arrest in G0/G1 phase, leading to impaired differentiation into mature adipocytes, upon which abnormal mitotic clonal expansion and reduced expression of adipogenic markers were exhibited. These results suggest that ZFP251 deficiency causes impaired adipogenesis and adipocyte hypertrophy, leading to dysfunction of WAT.

Exosomal miR-1304-3p promotes breast cancer progression in African Americans by activating cancer-associated adipocytes

Breast cancer displays disparities in mortality between African Americans and Caucasian Americans. However, the exact molecular mechanisms remain elusive. Here, we identify miR-1304-3p as the most upregulated microRNA in African American patients. Importantly, its expression significantly correlates with poor progression-free survival in African American patients. Ectopic expression of miR-1304 promotes tumor progression in vivo. Exosomal miR-1304-3p activates cancer-associated adipocytes that release lipids and enhance cancer cell growth. Moreover, we identify the anti-adipogenic gene GATA2 as the target of miR-1304-3p. Notably, a single nucleotide polymorphism (SNP) located in the miR-1304 stem-loop region shows a significant difference in frequencies of the G allele between African and Caucasian American groups, which promotes the maturation of miR-1304-3p. Therefore, our results reveal a mechanism of the disparity in breast cancer progression and suggest a potential utility of miR-1304-3p and the associated SNP as biomarkers for predicting the outcome of African American patients.

Identification of biomarkers in nonalcoholic fatty liver disease: A machine learning method and experimental study

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease. However, the early diagnosis of NAFLD is challenging. Thus, the purpose of this study was to identify diagnostic biomarkers of NAFLD using machine learning algorithms. Differentially expressed genes between NAFLD and normal samples were identified separately from the GEO database. The key DEGs were selected through a protein‒protein interaction network, and their biological functions were analysed. Next, three machine learning algorithms were selected to construct models of NAFLD separately, and the model with the smallest sample residual was determined to be the best model. Then, logistic regression analysis was used to judge the accuracy of the five genes in predicting the risk of NAFLD. A single-sample gene set enrichment analysis algorithm was used to evaluate the immune cell infiltration of NAFLD, and the correlation between diagnostic biomarkers and immune cell infiltration was analysed. Finally, 10 pairs of peripheral blood samples from NAFLD patients and normal controls were collected for RNA isolation and quantitative real-time polymerase chain reaction for validation. Taken together, CEBPD, H4C11, CEBPB, GATA3, and KLF4 were identified as diagnostic biomarkers of NAFLD by machine learning algorithms and were related to immune cell infiltration in NAFLD. These key genes provide novel insights into the mechanisms and treatment of patients with NAFLD.

In Vitro and In Vivo Validation of GATA-3 Suppression for Induction of Adipogenesis and Improving Insulin Sensitivity

Impaired adipogenesis is associated with the development of insulin resistance and an increased risk of type 2 diabetes (T2D). GATA Binding Protein 3 (GATA3) is implicated in impaired adipogenesis and the onset of insulin resistance. Therefore, we hypothesize that inhibition of GATA3 could promote adipogenesis, restore healthy fat distribution, and enhance insulin signaling. Primary human preadipocytes were treated with GATA3 inhibitor (DNAzyme hgd40). Cell proliferation, adipogenic capacity, gene expression, and insulin signaling were measured following well-established protocols. BALB/c mice were treated with DNAzyme hgd40 over a period of 2 weeks. Liposomes loaded with DNAzyme hgd40, pioglitazone (positive), or vehicle (negative) controls were administered subcutaneously every 2 days at the right thigh. At the end of the study, adipose tissues were collected and weighed from the site of injection, the opposite side, and the omental depot. Antioxidant enzyme (superoxide dismutase and catalase) activities were assessed in animals’ sera, and gene expression was measured using well-established protocols. In vitro GATA3 inhibition induced the adipogenesis of primary human preadipocytes and enhanced insulin signaling through the reduced expression of p70S6K. In vivo GATA3 inhibition promoted adipogenesis at the site of injection and reduced MCP-1 expression. GATA3 inhibition also reduced omental tissue size and PPARγ expression. These findings suggest that modulating GATA3 expression offers a potential therapeutic benefit by correcting impaired adipogenesis, promoting healthy fat distribution, improving insulin sensitivity, and potentially lowering the risk of T2D.

Statistical estimates of multiple transcription factors binding in the model plant genomes based on ChIP-seq data

The development of high-throughput genomic sequencing coupled with chromatin immunoprecipitation technologies allows studying the binding sites of the protein transcription factors (TF) in the genome scale. The growth of data volume on the experimentally determined binding sites raises qualitatively new problems for the analysis of gene expression regulation, prediction of transcription factors target genes, and regulatory gene networks reconstruction. Genome regulation remains an insufficiently studied though plants have complex molecular regulatory mechanisms of gene expression and response to environmental stresses. It is important to develop new software tools for the analysis of the TF binding sites location and their clustering in the plant genomes, visualization, and the following statistical estimates. This study presents application of the analysis of multiple TF binding profiles in three evolutionarily distant model plant organisms. The construction and analysis of non-random ChIP-seq binding clusters of the different TFs in mammalian embryonic stem cells were discussed earlier using similar bioinformatics approaches. Such clusters of TF binding sites may indicate the gene regulatory regions, enhancers and gene transcription regulatory hubs. It can be used for analysis of the gene promoters as well as a background for transcription networks reconstruction. We discuss the statistical estimates of the TF binding sites clusters in the model plant genomes. The distributions of the number of different TFs per binding cluster follow same power law distribution for all the genomes studied. The binding clusters in Arabidopsis thaliana genome were discussed here in detail.

New Insights on the Role of Connexins and Gap Junctions Channels in Adipose Tissue and Obesity

Due to the inability to curb the excessive increase in the prevalence of obesity and overweight, it is necessary to comprehend in more detail the factors involved in the pathophysiology and to appreciate more clearly the biochemical and molecular mechanisms of obesity. Thus, understanding the biological regulation of adipose tissue is of fundamental relevance. Connexin, a protein that forms intercellular membrane channels of gap junctions and unopposed hemichannels, plays a key role in adipogenesis and in the maintenance of adipose tissue homeostasis. The expression and function of Connexin 43 (Cx43) during the different stages of the adipogenesis are differentially regulated. Moreover, it has been shown that cell–cell communication decreases dramatically upon differentiation into adipocytes. Furthermore, inhibition of Cx43 degradation or constitutive overexpression of Cx43 blocks adipocyte differentiation. In the first events of adipogenesis, the connexin is highly phosphorylated, which is likely associated with enhanced Gap Junction (GJ) communication. In an intermediate state of adipocyte differentiation, Cx43 phosphorylation decreases, as it is displaced from the membrane and degraded through the proteasome; thus, Cx43 total protein is reduced. Cx is involved in cardiac disease as well as in obesity-related cardiovascular diseases. Different studies suggest that obesity together with a high-fat diet are related to the production of remodeling factors associated with expression and distribution of Cx43 in the atrium.

Molecular mechanism of anti-adipogenic effect of vitexin in differentiating hMSCs

In this study, we evaluated a detailed molecular mechanism of anti-adipogenic activity of vitexin, apigenin flavone glucoside, present in germinated fenugreek seeds, in differentiating human mesenchymal stem cells (hMSCs). The lipid content of differentiated adipocytes was estimated by ORO staining. Effect on mitotic clonal expansion was checked by cell cycle analysis. Expression of early and terminal adipocyte differentiation markers, anti- and pro-adipogenic transcription factors and signalling intermediates regulating them was evaluated at RNA and protein level. We found vitexin to be non-cytotoxic up to 20 μM at which intracellular lipid accumulation was significantly decreased. Cell cycle analysis suggested that vitexin does not affect mitotic clonal expansion. Expression of early and late differentiation markers, such as CEBPα, CEBPβ, PPARγ, FABP4, perilipin, adiponectin and Glut4 was significantly reduced in the presence of vitexin. Expression of KLF4 and KLF15, positive regulators of PPARγ, was decreased, whereas that of negative regulators, namely KLF2, GATA2, miR20a, miR27a, miR27b, miR128, miR130a, miR130b, miR182 and miR548 increased with vitexin treatment. This effect was mediated by the activation of the AMP-activated protein kinase (AMPK) pathway via the activation of LepR and additionally by inhibiting ROS. Thus, our results showed that vitexin regulates the expression of PPARγ and inhibits adipogenesis of hMSCs at an early stage of differentiation.

Metabolic gene regulation by Drosophila GATA transcription factor Grain

Nutrient-dependent gene regulation critically contributes to homeostatic control of animal physiology in changing nutrient landscape. In Drosophila, dietary sugars activate transcription factors (TFs), such as Mondo-Mlx, Sugarbabe and Cabut, which control metabolic gene expression to mediate physiological adaptation to high sugar diet. TFs that correspondingly control sugar responsive metabolic genes under conditions of low dietary sugar remain, however, poorly understood. Here we identify a role for Drosophila GATA TF Grain in metabolic gene regulation under both low and high sugar conditions. De novo motif prediction uncovered a significant over-representation of GATA-like motifs on the promoters of sugar-activated genes in Drosophila larvae, which are regulated by Grain, the fly ortholog of GATA1/2/3 subfamily. grain expression is activated by sugar in Mondo-Mlx-dependent manner and it contributes to sugar-responsive gene expression in the fat body. On the other hand, grain displays strong constitutive expression in the anterior midgut, where it drives lipogenic gene expression also under low sugar conditions. Consistently with these differential tissue-specific roles, Grain deficient larvae display delayed development on high sugar diet, while showing deregulated central carbon and lipid metabolism primarily on low sugar diet. Collectively, our study provides evidence for the role of a metazoan GATA transcription factor in nutrient-responsive metabolic gene regulation in vivo.

An RNAi Screening of Clinically Relevant Transcription Factors Regulating Human Adipogenesis and Adipocyte Metabolism

CONTEXT

Healthy hyperplasic (many but smaller fat cells) white adipose tissue (WAT) expansion is mediated by recruitment, proliferation and/or differentiation of new fat cells. This process (adipogenesis) is controlled by transcriptional programs that have been mostly identified in rodents.

OBJECTIVE

A systemic investigation of adipogenic human transcription factors (TFs) that are relevant for metabolic conditions has not been revealed previously.

METHODS

TFs regulated in WAT by obesity, adipose morphology, cancer cachexia, and insulin resistance were selected from microarrays. Their role in differentiation of human adipose tissue-derived stem cells (hASC) was investigated by RNA interference (RNAi) screen. Lipid accumulation, cell number, and lipolysis were measured for all screened factors (148 TFs). RNA (RNAseq), protein (Western blot) expression, insulin, and catecholamine responsiveness were examined in hASC following siRNA treatment of selected target TFs.

RESULTS

Analysis of TFs regulated by metabolic conditions in human WAT revealed that many of them belong to adipogenesis-regulating pathways. The RNAi screen identified 39 genes that affected fat cell differentiation in vitro, where 11 genes were novel. Of the latter JARID2 stood out as being necessary for formation of healthy fat cell metabolic phenotype by regulating expression of multiple fat cell phenotype-specific genes.

CONCLUSION

This comprehensive RNAi screening in hASC suggests that a large proportion of WAT TFs that are impacted by metabolic conditions might be important for hyperplastic adipose tissue expansion. The screen also identified JARID2 as a novel TF essential for the development of functional adipocytes.

Identification and functional prediction of long noncoding RNAs related to intramuscular fat content in Laiwu pigs

Objective

Intramuscular fat (IMF) is a critical economic indicator of pork quality. Studies on IMF among different pig breeds have been performed via high-throughput sequencing, but comparisons within the same pig breed remain unreported.

Methods

This study was performed to explore the gene profile and identify candidate long noncoding RNA (lncRNAs) and mRNAs associated with IMF deposition among Laiwu pigs with different IMF contents. Based on the longissimus dorsi muscle IMF content, eight pigs from the same breed and management were selected and divided into two groups: a high IMF (>12%, H) and low IMF group (<5%, L). Whole-transcriptome sequencing was performed to explore the differentially expressed (DE) genes between these two groups.

Results

The IMF content varied greatly among Laiwu pig individuals (2.17% to 13.93%). Seventeen DE lncRNAs (11 upregulated and 6 downregulated) and 180 mRNAs (112 upregulated and 68 downregulated) were found. Gene Ontology analysis indicated that the following biological processes played an important role in IMF deposition: fatty acid and lipid biosynthetic processes; the extracellular signal-regulated kinase cascade; and white fat cell differentiation. In addition, the peroxisome proliferator-activated receptor, phosphatidylinositol-3-kinase-protein kinase B, and mammalian target of rapamycin pathways were enriched in the pathway analysis. Intersection analysis of the target genes of DE lncRNAs and mRNAs revealed seven candidate genes associated with IMF accumulation. Five DE lncRNAs and 20 DE mRNAs based on the pig quantitative trait locus database were identified and shown to be related to fat deposition. The expression of five DE lncRNAs and mRNAs was verified by quantitative real time polymerase chain reaction (qRT-PCR). The results of qRT-PCR and RNA-sequencing were consistent.

Conclusion

These results demonstrated that the different IMF contents among pig individuals may be due to the DE lncRNAs and mRNAs associated with lipid droplets and fat deposition.

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.

lncSAMM50 Enhances Adipogenic Differentiation of Buffalo Adipocytes With No Effect on Its Host Gene

Fat deposition is one of the most important traits that are mediated by a set of complex regulatory factors in meat animals. Several researches have revealed the significant role of long non-coding RNAs (lncRNAs) in fat deposition while the precise regulatory mechanism is still largely elusive. In this study, we investigated the lncRNA profiles of adipose and muscle tissues in buffalo by using the Illumina HiSeq 3000 platform. In total, 43,809 lncRNAs were finally identified based on the computer algorithm. A comparison analysis revealed 241 lncRNAs that are differentially expressed (DE) in adipose and muscle tissues. We focused on lncSAMM50, a DE lncRNA that has a high expression in adipose tissue. Sequence alignment showed that lncSAMM50 is transcribed from the antisense strand of the upstream region of sorting and assembly machinery component 50 homolog (SAMM50), a gene involved in the function of mitochondrion and is subsequently demonstrated to inhibit the adipogenic differentiation of 3T3-L1 adipocyte cells in this study. lncSAMM50 is highly expressed in adipose tissue and upregulated in the mature adipocytes and mainly exists in the nucleus. Gain-of-function experiments demonstrated that lncSAMM50 promotes the adipogenic differentiation by upregulating adipogenic markers but with no effect on its host gene SAMM50 in buffalo adipocytes. These results indicate that lncSAMM50 enhances fat deposition in buffalo and provide a new factor for the regulatory network of adipogenesis.

Transient Delivery of A-C/EBP Protein Perturbs Differentiation of 3T3-L1 Cells and Induces Preadipocyte Marker Genes

Transformation of committed 3T3-L1 preadipocytes to lipid-laden adipocytes involves the timely appearance of numerous transcription factors (TFs); foremost among them, C/EBPβ is expressed during the early phases of differentiation. Here, we describe liposome-mediated protein transfection approach to rapidly downregulate C/EBPβ by A-C/EBP protein inhibitor. Signals from EGFP-tagged A-C/EBP protein were observed in 3T3-L1 cells within 2 h of transfections, whereas for A-C/EBP gene transfections, equivalent signals appeared in 48 h. Following transient transfections, the expression profiles of 24 marker genes belonging to pro- and anti-adipogenic, cell cycle, and preadipocyte pathways were analyzed. Expectedly, the mRNA and protein expression profiles of adipocyte marker genes showed lower expression in both A-C/EBP protein- and gene-transfected samples. Interestingly, for preadipocytes and cell fate determinant genes, striking differences were observed between A-C/EBP protein- and A-C/EBP gene-transfected samples. Preadipocyte differentiation factors Stat5a and Creb were downregulated in A-C/EBP protein samples. Five preadipocyte markers, namely, Pdgfrα, Pdgfrβ, Ly6A, CD34, and Itgb1, showed high expression in A-C/EBP protein samples, whereas only Ly6A and CD34 were expressed in A-C/EBP gene-transfected samples. Pdgfrα and Pdgfrβ, two known cell fate markers, were expressed in A-C/EBP protein-transfected samples, suggesting a possible reversal of differentiation. Our study provides evidences for the immediate and efficient knockdown of C/EBPβ protein to understand time-dependent preadipocytes differentiation.

Epigenetic Regulation of Adipogenesis in Development of Metabolic Syndrome

Obesity is one of the biggest public health concerns identified by an increase in adipose tissue mass as a result of adipocyte hypertrophy and hyperplasia. Pertaining to the importance of adipose tissue in various biological processes, any alteration in its function results in impaired metabolic health. In this review, we discuss how adipose tissue maintains the metabolic health through secretion of various adipokines and inflammatory mediators and how its dysfunction leads to the development of severe metabolic disorders and influences cancer progression. Impairment in the adipocyte function occurs due to individuals' genetics and/or environmental factor(s) that largely affect the epigenetic profile leading to altered gene expression and onset of obesity in adults. Moreover, several crucial aspects of adipose biology, including the regulation of different transcription factors, are controlled by epigenetic events. Therefore, understanding the intricacies of adipogenesis is crucial for recognizing its relevance in underlying disease conditions and identifying the therapeutic interventions for obesity and metabolic syndrome.

Adipogenesis as a Potential Anti-Obesity Target: A Review of Pharmacological Treatment and Natural Products

Obesity is recognized as a severe threat to overall human health and is associated with type 2 diabetes mellitus, dyslipidemia, hypertension, and cardiovascular diseases. Abnormal expansion of white adipose tissue involves increasing the existing adipocytes' cell size or increasing the number through the differentiation of new adipocytes. Adipogenesis is a process of proliferation and differentiation of adipocyte precursor cells in mature adipocytes. As a key process in determining the number of adipocytes, it is a possible therapeutic approach for obesity. Therefore, it is necessary to identify the molecular mechanisms involved in adipogenesis that could serve as suitable therapeutic targets. Reducing bodyweight is regarded as a major health benefit. Limited efficacy and possible side effects and drug interactions of available anti-obesity treatment highlight a constant need for finding novel efficient and safe anti-obesity ingredients. Numerous studies have recently investigated the inhibitory effects of natural products on adipocyte differentiation and lipid accumulation. Possible anti-obesity effects of natural products include the induction of apoptosis, cell-cycle arrest or delayed progression, and interference with transcription factor cascade or intracellular signaling pathways during the early phase of adipogenesis.

GATA-3 as a Potential Therapeutic Target for Insulin Resistance and Type 2 Diabetes Mellitus

Impaired adipogenesis plays an important role in the development of obesity-associated insulin resistance and type 2 diabetes as it leads to ectopic fat deposition. The anti-adipogenic transcription factor GATA-3 was identified as one of the potential molecular targets responsible for the impairment of adipogenesis. The expression of GATA-3 is higher in insulinresistant obese individuals compared to BMI-matched insulin-sensitive counterparts. Adipose tissue inflammation is a crucial mediator of this process. Hyperglycemia mediates the activation of the immune system, partially through upregulation of GATA- 3, causing exacerbation of the inflammatory state associated with obesity. This review discusses the evidence supporting the inhibition of GATA-3 as a useful therapeutic strategy in obesity-associated insulin resistance and type 2 diabetes, through up-regulation adipogenesis and amelioration of the immune response.

New insights of Krüppel-like transcription factors in adipogenesis and the role of their regulatory neighbors

Obesity is a serious public health problem associated with predisposition to develop metabolic diseases. Over the past decade, several studies in vitro and in vivo have shown that the activity of Krüppel-like factors (KLFs) regulates adipogenesis, adipose tissue function and metabolism. Comprehension of both the origin and development of adipocytes and of adipose tissue could provide new insights into therapeutic strategies to contend against obesity and related metabolic diseases. This review focus on the transcriptional role that KLF family members play during adipocyte differentiation, describes their main interactions and the mechanisms involved in this fine-tuned developmental process. We also summarize new findings of the involvement of several effectors that modulate KLFs expression during adipogenesis, including growth factors, circadian clock proteins, interleukins, nuclear receptors, protein kinases and importantly, microRNAs. Thus, KLFs regulation by these factors and emerging molecules might constitute a potential therapeutic target for anti-obesity intervention.

Suppression of GATA-3 increases adipogenesis, reduces inflammation and improves insulin sensitivity in 3T3L-1 preadipocytes

Impaired adipogenesis plays an important role in the development of obesity-associated insulin resistance and type 2 diabetes. Adipose tissue inflammation is a crucial mediator of this process. GATA-3 plays important roles in adipogenesis and inflammation. The aim of this study is to investigate the impact of GATA-3 suppression on improving adipogenesis, lowering inflammation and reversing insulin resistance. GATA-3 levels were measured in subcutaneous (SC) and omental (OM) adipose tissues obtained from insulin sensitive (IS) and insulin resistant (IR) obese individuals during weight reduction surgeries. The effect of GATA-3 suppression on adipogenesis, expression of inflammatory cytokines and insulin resistance biomarkers was performed in 3T3L-1 mouse preadipocytes via transfection with GATA-3-specific DNAzyme. GATA-3 expression was higher in OM compared to SC adipose tissues and in stromal vascular fraction-derived differentiating preadipocytes from IR obese individuals compared to their IS counterparts. Suppression of GATA-3 expression in 3T3L-1 mouse preadipocytes with GATA-3 specific inhibitor reversed 4-hydroxynonenal-induced impaired adipogenesis and triggered changes in the expression of insulin signaling-related genes. GATA-3 inhibition also modulated the expression of IL-6 and IL-10 and lowered the expression of insulin resistance biomarkers (PAI-1 and resistin) and insulin resistance phosphoproteins (p-BAD, p-PTEN and p-GSK3β). Inhibiting GATA-3 improves adipocytes differentiation, modulates the secretion of inflammatory cytokines and improves insulin sensitivity in insulin resistant cells. Suppression of GATA-3 could be a promising tool to improve adipogenesis, restore insulin sensitivity and lower obesity-associated inflammation in insulin resistant individuals.

A Novel GATA2 Protein Reporter Mouse Reveals Hematopoietic Progenitor Cell Types

The transcription factor (TF) GATA2 plays a key role in organ development and cell fate control in the central nervous, urogenital, respiratory, and reproductive systems, and in primitive and definitive hematopoiesis. Here, we generate a knockin protein reporter mouse line expressing a GATA2VENUS fusion from the endogenous Gata2 genomic locus, with correct expression and localization of GATA2VENUS in different organs. GATA2VENUS expression is heterogeneous in different hematopoietic stem and progenitor cell populations (HSPCs), identifies functionally distinct subsets, and suggests a novel monocyte and mast cell lineage bifurcation point. GATA2 levels further correlate with proliferation and lineage outcome of hematopoietic progenitors. The GATA2VENUS mouse line improves the identification of specific live cell types during embryonic and adult development and will be crucial for analyzing GATA2 protein dynamics in TF networks.

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A novel GATA2VENUS fusion mouse line to report GATA2 protein expression

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VENUS fusion does not alter GATA2 expression or disturb development or homeostasis

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GATA2 expression identifies functionally distinct HSPC subpopulations

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GATA2 expression unveils an earlier monocyte-mast cell lineage bifurcation point

GATA Binding Protein 3 Is a Direct Target of Kruppel-Like Transcription Factor 7 and Inhibits Chicken Adipogenesis

Kruppel-like transcription factor 7 (KLF7) is a negative regulator of adipogenesis, however, its precise mechanism is poorly understood. Our previous KLF7 ChIP-seq analysis showed that one of the KLF7 binding peaks was present upstream of GATA binding protein 3 (GATA3) in chicken preadipocytes. In the present study, we identified GATA3 as a target of KLF7. Overexpression analysis showed KLF7 markedly enhanced the endogenous expression of GATA3 in the immortalized chicken preadipcyte cell line (ICP2), and the luciferase reporter assay showed that KLF7 overexpression increased the reporter gene activity of the cloned upstream region (-5285/-4336 relative to the translation initiation codon ATG) of GATA3 in ICP2 and DF1 cells, and mutation of the putative KLF7 binding site abolished the promotive effect of KLF7 overexpression on the reporter gene activity of the cloned GATA3 upstream region. ChIP-qPCR further demonstrated that KLF7 directly bound to the GATA3 upstream region. Gene expression analysis showed that GATA3 mRNA expression in abdominal adipose tissue was significantly higher in lean chicken line than in the fat line at 2, 3, and 6 weeks of age. In addition, GATA3 mRNA expression markedly decreased during the preadipocyte differentiation. Furthermore, a functional study showed that GATA3 overexpression inhibited the differentiation of the ICP2 cells. Taken together, our results demonstrated that KLF7 inhibits chicken adipogenesis, at least in part through direct upregulation of GATA3.

Molecular Mechanisms of Adipogenesis: The Anti-adipogenic Role of AMP-Activated Protein Kinase

Obesity is now a widespread disorder, and its prevalence has become a critical concern worldwide, due to its association with common co-morbidities like cancer, cardiovascular diseases and diabetes. Adipose tissue is an endocrine organ and therefore plays a critical role in the survival of an individual, but its dysfunction or excess is directly linked to obesity. The journey from multipotent mesenchymal stem cells to the formation of mature adipocytes is a well-orchestrated program which requires the expression of several genes, their transcriptional factors, and signaling intermediates from numerous pathways. Understanding all the intricacies of adipogenesis is vital if we are to counter the current epidemic of obesity because the limited understanding of these intricacies is the main barrier to the development of potent therapeutic strategies against obesity. In particular, AMP-Activated Protein Kinase (AMPK) plays a crucial role in regulating adipogenesis – it is arguably the central cellular energy regulation protein of the body. Since AMPK promotes the development of brown adipose tissue over that of white adipose tissue, special attention has been given to its role in adipose tissue development in recent years. In this review, we describe the molecular mechanisms involved in adipogenesis, the role of signaling pathways and the substantial role of activated AMPK in the inhibition of adiposity, concluding with observations which will support the development of novel chemotherapies against obesity epidemics.

Fumarate and oxidative stress synergize to promote stability of C/EBP homologous protein in the adipocyte

C/EBP homologous protein (CHOP) is a transcription factor that is elevated in adipose tissue across many models of diabetes and metabolic stress. Although increased CHOP levels are associated with the terminal response to endoplasmic reticulum stress and apoptosis, there is no evidence for CHOP mediated apoptosis in the adipose tissue during diabetes. CHOP protein levels increase in parallel with protein succination, a fumarate derived cysteine modification, in the adipocyte during metabolic stress. We investigated the factors contributing to sustained CHOP proteins levels in the adipocyte, with an emphasis on the regulation of CHOP protein turnover by metabolite-driven modification of Keap1 cysteines. CHOP protein stability was investigated in conditions of nutrient stress due to high glucose or elevated fumarate (fumarase knockdown model); where cysteine succination is specifically elevated. CHOP protein turnover is significantly reduced in models of elevated glucose and fumarate with a ~30% increase in CHOP stability (p > 0.01), in part due to decreased CHOP phosphorylation. Sustained CHOP levels occur in parallel with elevated heme-oxygenase-1, a production of increased Nrf2 transcriptional activity and Keap1 modification. While Keap1 is directly succinated in the presence of excess fumarate derived from genetic knockdown of fumarase (fumarate levels are elevated >20-fold), it is the oxidative modification of Keap1 that predominates in adipocytes matured in high glucose (fumarate increases 4-5 fold). Elevated fumarate indirectly regulates CHOP stability through the induction of oxidative stress. The antioxidant N-acetylcysteine (NAC) reduces fumarate levels, protein succination and CHOP levels in adipocytes matured in high glucose. Elevated CHOP does not contribute elevated apoptosis in adipocytes, but plays a redox-dependent role in decreasing the adipocyte secretion of interleukin-13, an anti-inflammatory chemokine. NAC treatment restores adipocyte IL-13 secretion, confirming the redox-dependent regulation of a potent anti-inflammatory eotaxin. This study demonstrates that physiological increases in the metabolite fumarate during high glucose exposure contributes to the presence of oxidative stress and sustained CHOP levels in the adipocyte during diabetes. The results reveal a novel metabolic link between mitochondrial metabolic stress and reduced anti-inflammatory adipocyte signaling as a consequence of reduced CHOP protein turnover.

Dynamic regulation of GATA2 in fate determination in hematopoiesis: possible approach to hPSC-derived hematopoietic stem/progenitor cells

GATA2, a principal member of the GATA family, plays important roles in the generation and maintenance of hematopoietic stem/progenitor cells. Among the three mRNA transcripts, the distal first exon of GATA2 (IS exon) is specific for hematopoietic and neuronal cells. GATA2 mutants with abnormal expression are often present in acute myeloid leukemia-related familial diseases and myelodysplastic syndrome, indicating the crucial significance of GATA2 in the proper maintenance of blood system functions. This article offers an overview of the regulation dynamics and function of GATA2 in the generation, proliferation, and function of hematopoietic stem cells in both mouse and human models. We acknowledge the current progress in the cell fate determination mechanism by dynamic GATA2 expression. The gene modification approaches for inspecting the role of GATA2 in definitive hematopoiesis demonstrate the potential for acquiring hPSC-derived hematopoietic stem cells via manipulated GATA2 regulation.

The transcription factor NKX1-2 promotes adipogenesis and may contribute to a balance between adipocyte and osteoblast differentiation

Although adipogenesis is mainly controlled by a small number of master transcription factors, including CCAAT/enhancer-binding protein family members and peroxisome proliferator-activated receptor γ (PPARγ), other transcription factors also are involved in this process. Thyroid cancer cells expressing a paired box 8 (PAX8)-PPARγ fusion oncogene trans-differentiate into adipocyte-like cells in the presence of the PPARγ ligand pioglitazone, but this trans-differentiation is inhibited by the transcription factor NK2 homeobox 1 (NKX2-1). Here, we tested whether NKX family members may play a role also in normal adipogenesis. Using quantitative RT-PCR (RT-qPCR), we examined the expression of all 14 NKX family members during 3T3-L1 adipocyte differentiation. We found that most NKX members, including NKX2-1, are expressed at very low levels throughout differentiation. However, mRNA and protein expression of a related family member, NKX1-2, was induced during adipocyte differentiation. NKX1-2 also was up-regulated in cultured murine ear mesenchymal stem cells (EMSCs) during adipogenesis. Importantly, shRNA-mediated NKX1-2 knockdown in 3T3-L1 preadipocytes or EMSCs almost completely blocked adipocyte differentiation. Furthermore, NKX1-2 overexpression promoted differentiation of the ST2 bone marrow-derived mesenchymal precursor cell line into adipocytes. Additional findings suggested that NKX1-2 promotes adipogenesis by inhibiting expression of the antiadipogenic protein COUP transcription factor II. Bone marrow mesenchymal precursor cells can differentiate into adipocytes or osteoblasts, and we found that NKX1-2 both promotes ST2 cell adipogenesis and inhibits their osteoblastogenic differentiation. These results support a role for NKX1-2 in promoting adipogenesis and possibly in regulating the balance between adipocyte and osteoblast differentiation of bone marrow mesenchymal precursor cells.

Identification of differentially expressed genes and pathways between intramuscular and abdominal fat-derived preadipocyte differentiation of chickens in vitro

BACKGROUND

The distribution and deposition of fat tissue in different parts of the body are the key factors affecting the carcass quality and meat flavour of chickens. Intramuscular fat (IMF) content is an important factor associated with meat quality, while abdominal fat (AbF) is regarded as one of the main factors affecting poultry slaughter efficiency. To investigate the differentially expressed genes (DEGs) and molecular regulatory mechanisms related to adipogenic differentiation between IMF- and AbF-derived preadipocytes, we analysed the mRNA expression profiles in preadipocytes (0d, Pre-) and adipocytes (10d, Ad-) from IMF and AbF of Gushi chickens.

RESULTS

AbF-derived preadipocytes exhibited a higher adipogenic differentiation ability (96.4% + 0.6) than IMF-derived preadipocytes (86.0% + 0.4) (p < 0.01). By Ribo-Zero RNA sequencing, we obtained 4403 (2055 upregulated and 2348 downregulated) and 4693 (2797 upregulated and 1896 downregulated) DEGs between preadipocytes and adipocytes in the IMF and Ad groups, respectively. For IMF-derived preadipocyte differentiation, pathways related to the PPAR signalling pathway, ECM-receptor interaction and focal adhesion pathway were significantly enriched. For AbF-derived preadipocyte differentiation, the steroid biosynthesis pathways, calcium signaling pathway and ECM-receptor interaction pathway were significantly enriched. A large number of DEGs related to lipid metabolism, fatty acid metabolism and preadipocyte differentiation, such as PPARG, ACSBG2, FABP4, FASN, APOA1 and INSIG1, were identified in our study.

CONCLUSION

This study revealed large transcriptomic differences between IMF- and AbF-derived preadipocyte differentiation. A large number of DEGs and transcription factors that were closely related to fatty acid metabolism, lipid metabolism and preadipocyte differentiation were identified in the present study. Additionally, the microenvironment of IMF- and AbF-derived preadipocyte may play a significant role in adipogenic differentiation. This study provides valuable evidence to understand the molecular mechanisms underlying adipogenesis and fat deposition in chickens.

Erythropoietin modulates bone marrow stromal cell differentiation

Erythropoietin is essential for bone marrow erythropoiesis and erythropoietin receptor on non-erythroid cells including bone marrow stromal cells suggests systemic effects of erythropoietin. Tg6 mice with chronic erythropoietin overexpression have a high hematocrit, reduced trabecular and cortical bone and bone marrow adipocytes, and decreased bone morphogenic protein 2 driven ectopic bone and adipocyte formation. Erythropoietin treatment (1 200 IU·kg^–1) for 10 days similarly exhibit increased hematocrit, reduced bone and bone marrow adipocytes without increased osteoclasts, and reduced bone morphogenic protein signaling in the bone marrow. Interestingly, endogenous erythropoietin is required for normal differentiation of bone marrow stromal cells to osteoblasts and bone marrow adipocytes. ΔEpoR_E mice with erythroid restricted erythropoietin receptor exhibit reduced trabecular bone, increased bone marrow adipocytes, and decreased bone morphogenic protein 2 ectopic bone formation. Erythropoietin treated ΔEpoR_E mice achieved hematocrit similar to wild-type mice without reduced bone, suggesting that bone reduction with erythropoietin treatment is associated with non-erythropoietic erythropoietin response. Bone marrow stromal cells from wild-type, Tg6, and ΔEpoR_E-mice were transplanted into immunodeficient mice to assess development into a bone/marrow organ. Like endogenous bone formation, Tg6 bone marrow cells exhibited reduced differentiation to bone and adipocytes indicating that high erythropoietin inhibits osteogenesis and adipogenesis, while ΔEpoR_E bone marrow cells formed ectopic bones with reduced trabecular regions and increased adipocytes, indicating that loss of erythropoietin signaling favors adipogenesis at the expense of osteogenesis. In summary, endogenous erythropoietin signaling regulates bone marrow stromal cell fate and aberrant erythropoietin levels result in their impaired differentiation.

Transcriptional and Epigenomic Regulation of Adipogenesis

Understanding adipogenesis, the process of adipocyte development, may provide new ways to treat obesity and related metabolic diseases. Adipogenesis is controlled by coordinated actions of lineage-determining transcription factors and epigenomic regulators. Peroxisome proliferator-activated receptor gamma (PPARγ) and C/EBPα are master "adipogenic" transcription factors. In recent years, a growing number of studies have reported the identification of novel transcriptional and epigenomic regulators of adipogenesis. However, many of these novel regulators have not been validated in adipocyte development in vivo and their working mechanisms are often far from clear. In this minireview, we discuss recent advances in transcriptional and epigenomic regulation of adipogenesis, with a focus on factors and mechanisms shared by both white adipogenesis and brown adipogenesis. Studies on the transcriptional regulation of adipogenesis highlight the importance of investigating adipocyte differentiation in vivo rather than drawing conclusions based on knockdown experiments in cell culture. Advances in understanding of epigenomic regulation of adipogenesis have revealed critical roles of histone methylation/demethylation, histone acetylation/deacetylation, chromatin remodeling, DNA methylation, and microRNAs in adipocyte differentiation. We also discuss future research directions that may help identify novel factors and mechanisms regulating adipogenesis.

The Gata2 repression during 3T3-L1 preadipocyte differentiation is dependent on a rapid decrease in histone acetylation in response to glucocorticoid receptor activation

The transcription factor GATA2 is an anti-adipogenic factor whose expression is downregulated during adipocyte differentiation. The present study attempted to clarify the molecular mechanism underlying the GATA2 repression and found that the repression is dependent on the activation of the glucocorticoid receptor (GR) during 3T3-L1 preadipocyte differentiation. Although several recognition sequences for GR were found in both the proximal and distal regions of the Gata2 locus, the promoter activity was not affected by the GR activation in the reporter assays, and the CRISPR-Cas9-mediated deletion of the two distal regions of the Gata2 locus was not involved in the GR-mediated Gata2 repression. Notably, the level of histone acetylation was markedly reduced at the Gata2 locus during 3T3-L1 differentiation, and the GR-mediated Gata2 repression was significantly relieved by histone deacetylase inhibition. These results suggest that GR regulates the Gata2 gene by reducing histone acetylation in the early phase of adipogenesis.

Adipogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells in Pig Transgenic Model Expressing Human Mutant Huntingtin

BACKGROUND

Although the highest expression of mutant huntingtin (mtHtt) was observed in the brain, its negative effects were also apparent in other tissues. Specifically, mtHtt impairs metabolic homeostasis and causes transcriptional dysregulation in adipose tissue. Adipogenic differentiation can be induced by the activation of two transcription factors: CCAAT/enhancer-binding protein alpha (CEBPα) and peroxisome proliferator-activated receptor gamma (PPARγ). These same transcription factors were found to be compromised in some tissues of Huntington's disease (HD) mouse models and in lymphocytes of HD patients.

OBJECTIVE

This study investigated the adipogenic potential of mesenchymal stem cells (MSCs) derived from transgenic Huntington's disease (TgHD) minipigs expressing human mtHtt (1-548aa) containing 124 glutamines. Two differentiation conditions were used, employing PPARγ agonist rosiglitazone or indomethacin.

METHODS

Bone marrow MSCs were isolated from TgHD and WT minipig siblings and compared by their cluster of differentiation using flow cytometry. Their adipogenic potential in vitro was analyzed using quantitative immunofluorescence and western blot analysis of transcription factors and adipogenic markers.

RESULTS

Flow cytometry analysis did not reveal any significant difference between WT and TgHD MSCs. Nevertheless, following differentiation into adipocytes, the expression of CEBPα nuclear, PPARγ and adipogenic marker FABP4/AP2 were significantly lower in TgHD cells compared to WT cells. In addition, we proved both rosiglitazone and indomethacin to be efficient for adipogenic differentiation of porcine MSCs, with rosiglitazone showing a better adipogenic profile.

CONCLUSIONS

We demonstrated a negative influence of mtHtt on adipogenic differentiation of porcine MSCs in vitro associated with compromised expression of adipogenic transcription factors.

Elucidating the Preadipocyte and Its Role in Adipocyte Formation: a Comprehensive Review

Adipogenesis is a complex process whereby the multipotent adipose-derived stem cell is converted to a preadipocyte before terminal differentiation into the mature adipocyte. Preadipocytes are present throughout adult life, exhibit adipose fat depot specificity, and differentiate and proliferate from distinct progenitor cells. The mechanisms that promote preadipocyte commitment and maturation involve numerous protein factor regulators, epigenetic factors, and miRNAs. Detailed characterization of this process is currently an area of intense research and understanding the roles of preadipocytes in tissue plasticity may provide insight into novel approaches for tissue engineering, regenerative medicine and treating a host of obesity-related conditions. In the current study, we analyzed the current literature and present a review of the characteristics of transitioning adipocytes and detail how local microenvironments influence their progression towards terminal differentiation and maturation. Specifically, we detail the characterization of preadipocyte via surface markers, examine the signaling cascades and regulation behind adipogenesis and cell maturation, and survey their role in tissue plasticity and health and disease.