Oncostatin M decreases adiponectin expression and induces dedifferentiation of adipocytes by JAK3- and MEK-dependent pathways

The Impact of Resident Adipose Tissue Macrophages on Adipocyte Homeostasis and Dedifferentiation

Obesity is concurrent with immunological dysregulation, resulting in chronic low-grade inflammation and cellular dysfunction. In pancreatic islets, this loss of function has been correlated with mature β-cells dedifferentiating into a precursor-like state through constant exposure to inflammatory stressors. As mature adipocytes likewise have the capability to dedifferentiate in vitro and in vivo, we wanted to analyze this cellular change in relation to adipose tissue (AT) inflammation and adipose tissue macrophage (ATM) activity. Using our organotypic AT explant culture method combined with a double-reporter mouse model for labeling ATMs and mature adipocytes, we were able to visualize and quantify dedifferentiated fat (DFAT) cells in AT explants. Preliminary testing showed increased dedifferentiation after tamoxifen (TAM) stimulation, making TAM-dependent lineage-tracing models unsuitable for quantification of naturally occurring DFAT cells. The regulatory role of ATMs in adipocyte dedifferentiation was shown through macrophage depletion using Plexxicon 5622 or clodronate liposomes, which significantly increased DFAT cell levels. Subsequent bulk RNA sequencing of macrophage-depleted explants revealed enrichment of the tumor necrosis factor α (TNFα) signaling pathway as well as downregulation of associated genes. Direct stimulation with TNFα decreased adipocyte dedifferentiation, while application of a TNFα-neutralizing antibody did not significantly alter DFAT cell levels. Our findings suggest a regulatory role of resident ATMs in maintaining the mature adipocyte phenotype and preventing excessive adipocyte dedifferentiation. The specific regulatory pathways as well as the impact that DFAT cells might have on ATMs, and vice versa, are subject to further investigation.

Insights into the molecular changes of adipocyte dedifferentiation and its future research opportunities

Recent studies have challenged the traditional belief that mature fat cells are irreversibly differentiated and revealed they can dedifferentiate into fibroblast-like cells known as dedifferentiated fat (DFAT) cells. Resembling pluripotent stem cells, DFAT cells hold great potential as a cell source for stem cell therapy. However, there is limited understanding of the specific changes that occur following adipocyte dedifferentiation and the detailed regulation of this process. This review explores the epigenetic, genetic, and phenotypic alterations associated with DFAT cell dedifferentiation, identifies potential targets for clinical regulation and discusses the current applications and challenges in the field of DFAT cell research.

Oncostatin M promotes lipolysis in white adipocytes

Oncostatin M (OSM) is a member of the glycoprotein 130 cytokine family that is involved in chronic inflammation and increased in adipose tissue under obesity and insulin resistance. OSM was shown to inhibit adipogenesis, suppress browning, and contribute to insulin resistance in cultured white adipocytes. In contrast, OSM may have a metabolically favourable role on adipocytes in mouse models of obesity and insulin resistance. However, a putative role of OSM in modulating lipolysis has not been investigated in detail to date. To address this, cultured white adipocytes of mouse or human origin were exposed to 10 or 100 ng/ml of OSM for various time periods. In murine 3T3-L1 cells, OSM stimulation directly activated hormone-sensitive lipase (HSL) and other players of the lipolytic machinery, and dose-dependently increased free fatty acid and glycerol release. In parallel, OSM attenuated insulin-mediated suppression of lipolysis and induced phosphorylation of serine-residues on the insulin receptor substrate-1 (IRS1) protein. Key experiments were verified in a second murine and a human adipocyte cell line. Inhibiton of extracellular signal-regulated kinase (ERK)-1/2 activation, abolished OSM-mediated HSL phosphorylation and lipolysis. In conclusion, OSM signalling directly promotes lipolysis in white adipocytes in an ERK1/2-dependent manner.

Biflavonoids from Ginkgo biloba leaves as a novel anti-atherosclerotic candidate: Inhibition potency and mechanistic analysis

BACKGROUND

Ginkgo biloba L. is one of the oldest trees on earth, and its leaves have been used since ages as herbal medicine to treat cerebrovascular disorders. It is worth noting that in addition to the widely concerned flavonoids and terpenoids, it also contains various thus far neglected biflavonoids. In fact, biflavonoids are flavonoids consisting of apigenin or its derivatives as monomeric scaffold, and are linked via C-C or C-O-C bond.

PURPOSE

Based on the structural similarity of flavonoids, we hypothesized that biflavonoids may play a potential role in the treatment of cerebrovascular diseases. Here, we describe the effectiveness and underlying mechanisms for prevention and treatment of atherosclerosis (AS) by biflavonoids.

STUDY DESIGN AND METHODS

Four main biflavonoids in Ginkgo biloba leaves were screened by oleic acid-induced lipid production in HepG2 cells. The non-covalent effects of biflavonoids on the potential targets of atherosclerosis were screened by reverse targeting and molecular dynamics simulation. The interactions between biflavonoids and potential targets were evaluated by an exogenous cell model, which verified the consistency of the simulation results.

CONCLUSION

Among all four biflavonoids, ginkgetin significantly inhibited oleic acid-induced lipid production in HepG2 cells and reduced total cholesterol and triglyceride levels. The interaction of ginkgetin with CDK2 through π-alkyl and hydrogen bonds increased the binding of molecules and proteins. Ginkgetin arrested the cells in the G1-S phase, which significantly inhibited abnormal cell growth which closely related to the occurrence and development of atherosclerosis. Biflavonoids could be a promising natural medicine for the treatment of atherosclerosis.

Potential key factors involved in regulating adipocyte dedifferentiation

Adipocytes are the key constituents of adipose tissue, and their de-differentiation process has been widely observed in physiological and pathological conditions. For obese people, the promotion of adipocyte de-differentiation or maintenance of an undifferentiated state of adipocytes may help to improve their metabolic condition. Thus, understanding the regulatory mechanisms of adipocyte de-differentiation is necessary for treating metabolic diseases. Attractively, in addition to intracellular signals regulating adipocyte de-differentiation, external factors such as temperature and pressure also affect adipocyte de-differentiation. In this review, we summarize the recent progress in the field and discuss the regulatory roles and mechanisms of involved endogenous and exogenous factors during the process of de-differentiation.

Oncostatin M suppresses browning of white adipocytes via gp130-STAT3 signaling

Objective

Obesity is associated with low-grade adipose tissue inflammation and locally elevated levels of several glycoprotein 130 (gp130) cytokines. The conversion of white into brown-like adipocytes (browning) may increase energy expenditure and revert the positive energy balance that underlies obesity. Although different gp130 cytokines and their downstream targets were shown to regulate expression of the key browning marker uncoupling protein 1 (Ucp1), it remains largely unknown how this contributes to the development and maintenance of obesity. Herein, we aim to study the role of gp130 cytokine signaling in white adipose tissue (WAT) browning in the obese state.

Methods

Protein and gene expression levels of UCP1 and other thermogenic markers were assessed in a subcutaneous adipocyte cell line, adipose tissue depots from control or adipocyte-specific gp130 knockout (gp130^Δadipo) mice fed either chow or a high-fat diet (HFD), or subcutaneous WAT biopsies from a human cohort of lean and obese subjects. WAT browning was modeled in vitro by exposing mature adipocytes to isoproterenol after stimulation with gp130 cytokines. ERK and JAK-STAT signaling were blocked using the inhibitors U0126 and Tofacitinib, respectively.

Results

Inguinal WAT of HFD-fed gp130^Δadipo mice exhibited significantly elevated levels of UCP1 and other browning markers such as Cidea and Pgc-1α. In vitro, treatment with the gp130 cytokine oncostatin M (OSM) lowered isoproterenol-induced UCP1 protein and gene expression levels in a dose-dependent manner. Mechanistically, OSM mediated the inhibition of Ucp1 via the JAK-STAT but not the ERK pathway. As with mouse data, OSM gene expression in human WAT positively correlated with BMI (r = 0.284, p = 0.021, n = 66) and negatively with UCP1 expression (r = −0.413, p < 0.001, n = 66).

Conclusions

Our data support the notion that OSM negatively regulates thermogenesis in WAT and thus may be an attractive target for treating obesity.

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OSM is regulated under obesity and negatively correlates with UCP1 in WAT.

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OSM suppresses isoproterenol-induced UCP1 in subcutaneous adipocytes.

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OSM signals through the gp130-STAT3 pathway to lower UCP1 expression.

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Obese mice lacking gp130 in adipocytes exhibit increased WAT browning.

Oncostatin M promotes hepatic progenitor cell activation and hepatocarcinogenesis via macrophage-derived tumor necrosis factor-α

Hepatocellular carcinoma (HCC) usually occurs at the late stage of chronic liver injury. Oncostatin M (OSM) is a tumor-associated cytokine highly expressed in cirrhosis and HCC patients; however, its role in hepatocarcinogenesis has not been clearly elucidated. In this study, we investigated the effect of OSM on HCC occurrence in a rat model of N-diethylnitrosamine-induced HCC. OSM overexpression significantly increased the number of tumor nodules and shortened the overall survival of the rats. Notably, OSM promoted HPC activation in vivo but did not directly regulate the proliferation of the HPC cell line in vitro. Further, OSM induced tumor necrosis factor-α (TNF-α) secretion and CD68⁺ macrophage accumulation, which were positively correlated with HPC activation. Additionally, TNF-α or macrophage depletion inhibited the promoting effect of OSM on hepatocarcinogenesis and HPC activation. Furthermore, OSM expression in the peritumoral tissues of HCC was positively correlated with poor overall survival of patients. In conclusion, OSM plays an important role in hepatocarcinogenesis by regulating the liver inflammation environment. Hence, OSM could be used as a potential target for HCC prevention and therapy or as an indicator of HCC prognosis.

Water-Stable Silver-Based Metal-Organic Frameworks of Quaternized Carboxylates and Their Antimicrobial Activity

Three-dimensional (3D) and two-dimensional (2D) Ag-based zwitterionic metal-organic frameworks (MOFs) [Ag₂(Cedcp)]_n (1, 3D, H₃CedcpBr denotes N-(carboxyethyl)-(3,5-dicarboxyl)-pyridinium bromide) and {[Ag₄(Cmdcp)₂(H₂O)₄]·4H₂O}_n (2, 2D, H₃CmdcpBr denotes N-(carboxymethyl)-(3,5-dicarboxyl)-pyridinium bromide) have been prepared and investigated for antimicrobial activity via minimal inhibition concentration (MIC) test and killing kinetic assay. Both MOFs 1 and 2 show good water stability and solubility ascribed to their characteristic aromatic rings and positively charged pyridinium of the ligands, as well as the presence of Ag⁺ on their surface, leading to strong antimicrobial activity and a wide antimicrobial spectrum toward Gram-negative and positive bacteria. The results indicated that MOF 2 possesses a faster antibacterial activity (60 min) than MOF 1 (120 min). Scanning electron microscopy analysis further suggests that the Ag-based MOFs are capable of rupturing the bacterial membrane, leading to cell death. Moreover, both MOFs exhibit little hemolytic activity against mouse erythrocytes and show good biocompatibility in vitro, rendering MOFs 1 and 2 potential therapeutic agents for diseases caused by bacteria.

A Role for Oncostatin M in the Impairment of Glucose Homeostasis in Obesity

CONTEXT

Oncostatin M (OSM) plays a key role in inflammation, but its regulation and function during obesity is not fully understood.

OBJECTIVE

The aim of this study was to evaluate the relationship of OSM with the inflammatory state that leads to impaired glucose homeostasis in obesity. We also assessed whether OSM immunoneutralization could revert metabolic disturbances caused by a high-fat diet (HFD) in mice.

DESIGN

28 patients with severe obesity were included and stratified into two groups: (1) glucose levels <100 mg/dL and (2) glucose levels >100 mg/dL. White adipose tissue was obtained to examine OSM gene expression. Human adipocytes were used to evaluate the effect of OSM in the inflammatory response, and HFD-fed C57BL/6J mice were injected with anti-OSM antibody to evaluate its effects.

RESULTS

OSM expression was elevated in subcutaneous and visceral fat from patients with obesity and hyperglycemia, and correlated with Glut4 mRNA levels, serum insulin, homeostatic model assessment of insulin resistance, and inflammatory markers. OSM inhibited adipogenesis and induced inflammation in human adipocytes. Finally, OSM receptor knockout mice had increased Glut4 mRNA levels in adipose tissue, and OSM immunoneutralization resulted in a reduction of glucose levels and Ccl2 expression in adipose tissue from HFD-fed mice.

CONCLUSIONS

OSM contributes to the inflammatory state during obesity and may be involved in the development of insulin resistance.

Molecular switch model for cardiomyocyte proliferation

This review deals with the human adult cardiomyocyte proliferation as a potential source for heart repair after injury. The mechanism to regain the proliferative capacity of adult cardiomyocytes is a challenge. However, recent studies are promising in showing that the ‘locked’ cell cycle of adult cardiomyocytes could be released through modulation of cell cycle checkpoints. In support of this are the signaling pathways of Notch, Hippo, Wnt, Akt and Jak/Stat that facilitate or inhibit the transition at cell cycle checkpoints. Cyclins and cyclin dependant kinases (CDKs) facilitate this transition which in turn is regulated by inhibitory action of pocket protein e.g. p21, p27 and p57. Transcription factors e.g. E2F, GATA4, TBx20 up regulate Cyclin A, A2, D, E, and CDK4 as promoters of cell cycle and Meis-1 and HIF-1 alpha down regulate cyclin D and E to inhibit the cell cycle. Paracrine factors like Neuregulin-1, IGF-1 and Oncostatin M and Extracellular Matrix proteins like Agrin have been involved in cardiomyocyte proliferation and dedifferentiation processes.

A molecular switch model is proposed that transforms the post mitotic cell into an actively dividing cell. This model shows how the cell cycle is regulated through on- and off switch mechanisms through interaction of transcription factors and signaling pathways with proteins of the cell cycle checkpoints. Signals triggered by injury may activate the right combination of the various pathways that can ‘switch on’ the proliferation signals leading to myocardial regeneration.

Structural Equation Modeling and Whole-Genome Scans Uncover Chromosome Regions and Enriched Pathways for Carcass and Meat Quality in Beef

Structural equation models involving latent variables are useful tools for formulating hypothesized models defined by theoretical variables and causal links between these variables. The objectives of this study were: (1) to identify latent variables underlying carcass and meat quality traits and (2) to perform whole-genome scans for these latent variables in order to identify genomic regions and individual genes with both direct and indirect effects. A total of 726 steers from an Angus-Brahman multibreed population with records for 22 phenotypes were used. A total of 480 animals were genotyped with the GGP Bovine F-250. The single-step genomic best linear unbiased prediction method was used to estimate the amount of genetic variance explained for each latent variable by chromosome regions of 20 adjacent SNP-windows across the genome. Three types of genetic effects were considered: (1) direct effects on a single latent phenotype; (2) direct effects on two latent phenotypes simultaneously; and (3) indirect effects. The final structural model included carcass quality as an independent latent variable and meat quality as a dependent latent variable. Carcass quality was defined by quality grade, fat over the ribeye and marbling, while the meat quality was described by juiciness, tenderness and connective tissue, all of them measured through a taste panel. From 571 associated genomic regions (643 genes), each one explaining at least 0.05% of the additive variance, 159 regions (179 genes) were associated with carcass quality, 106 regions (114 genes) were associated with both carcass and meat quality, 242 regions (266 genes) were associated with meat quality, and 64 regions (84 genes) were associated with carcass quality, having an indirect effect on meat quality. Three biological mechanisms emerged from these findings: postmortem proteolysis of structural proteins and cellular compartmentalization, cellular proliferation and differentiation of adipocytes, and fat deposition.

Induction of muscle stem cell quiescence by the secreted niche factor Oncostatin M

The balance between stem cell quiescence and proliferation in skeletal muscle is tightly controlled, but perturbed in a variety of disease states. Despite progress in identifying activators of stem cell proliferation, the niche factor(s) responsible for quiescence induction remain unclear. Here we report an in vivo imaging-based screen which identifies Oncostatin M (OSM), a member of the interleukin-6 family of cytokines, as a potent inducer of muscle stem cell (MuSC, satellite cell) quiescence. OSM is produced by muscle fibers, induces reversible MuSC cell cycle exit, and maintains stem cell regenerative capacity as judged by serial transplantation. Conditional OSM receptor deletion in satellite cells leads to stem cell depletion and impaired regeneration following injury. These results identify Oncostatin M as a secreted niche factor responsible for quiescence induction, and for the first time establish a direct connection between induction of quiescence, stemness, and transplantation potential in solid organ stem cells.

The factors that mediate quiescence of muscle stem cells are unknown. The authors show that Oncostatin M is produced by skeletal muscle, suppresses stem cell proliferation, and that its deletion in muscle results in stem cell depletion and impaired muscle regeneration following injury in mice.

CpG Oligodeoxynucleotides Downregulate Placental Adiponectin and Increase Embryo Loss in Non-Obese Diabetic Mice

PROBLEM

CpG oligodeoxynucleotides (ODNs) can induce immunological changes in non-obese diabetic (NOD) mice and increase embryo loss, but little is known about the mechanism. This study aimed to determine the role of adiponectin in CpG ODN-induced pregnancy failure.

METHOD OF STUDY

Oligodeoxynucleotide 1826 was intraperitoneally injected to NOD mice, and ODN 2216, ODN 2006, and ODN 2395 were used to stimulate human trophoblast cell lines to investigate adiponectin expression patterns and its possible effects on trophoblast function.

RESULTS

CpG ODNs downregulated adiponectin via the cJun N-terminal kinase signaling pathway and led to increased embryo loss (from 6.9 to 33.3%). ODN 2006 impaired human trophoblast cell migration, which was successfully rescued by adiponectin treatment.

CONCLUSION

CpG ODNs decreased placental adiponectin expression in NOD mice and impaired human trophoblast function and was associated with increased embryo loss. Adiponectin may therefore play an important protective role in the prevention of bacteria-induced pregnancy failure.

Oncostatin M-induced cardiomyocyte dedifferentiation regulates the progression of diabetic cardiomyopathy through B-Raf/Mek/Erk signaling pathway

It has been reported that oncostatin M (OSM) could initiate cardiomyocyte dedifferentiation both in vivo and in vitro. OSM-induced cardiomyocyte dedifferentiation might be a new target for the treatment of diabetic cardiomyopathy (DCM). This study was designed to determine the role of OSM in cardiomyocyte dedifferentiation and the progression of DCM. A mouse DCM model was established to evaluate the effects of OSM in vivo. Echocardiography was applied to determine cardiac function. Sirius red staining was used to detect fibrosis area. Transmission electron microscopy was used to evaluate mitochondria impairment. Real-time polymerase chain reaction and western blot analysis were performed to detect relative mRNA expressions and cardiomyocyte dedifferentiation-related protein expressions, respectively. OSM treatment induced similar impaired cardiac function and cardiac ultrastructure impairment to those detected in DCM mice. The expressions of dedifferentiation markers of cardiomyocyte (Runx1, and α-SM-actin) were up-regulated in the OSM-treated mice compared with those in the control group. To further demonstrate the important role of OSM, OSM receptor knockout (Oβ(ko)) mice were used. In Oβ(ko) mice, cardiomyocytes dedifferentiation markers of c-kit, Runx1, and atrial natriuretic peptide were down-regulated, with attenuated DCM injury and abrogated OSM/B-Raf/Mek/Erk signaling pathway. In conclusion, OSM-induced cardiomyocyte dedifferentiation plays a crucial role in the progression of DCM. The mechanism of OSM-induced cardiomyocyte dedifferentiation is associated with B-Raf/Mek/Erk signaling pathway through the OSM receptor Oβ.

Oncostatin m modulation of lipid storage

Oncostatin M (OSM) is a cytokine belonging to the gp130 family, whose members serve pleiotropic functions. However, several actions of OSM are unique from those of other gp130 cytokines, and these actions may have critical roles in inflammatory mechanisms influencing several metabolic and biological functions of insulin-sensitive tissues. In this review, the actions of OSM in adipose tissue and liver are discussed, with an emphasis on lipid metabolism.

Adipocyte-specific deficiency of Janus kinase (JAK) 2 in mice impairs lipolysis and increases body weight, and leads to insulin resistance with ageing

AIMS/HYPOTHESIS

The growing obesity epidemic necessitates a better understanding of adipocyte biology and its role in metabolism. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway mediates signalling by numerous cytokines and hormones that regulate adipocyte function, illustrating the physiological importance of adipose JAK-STAT. The aim of this study was to investigate potential roles of adipocyte JAK2, an essential player in the JAK-STAT pathway, in adipocyte biology and metabolism.

METHODS

We generated adipocyte-specific Jak2 knockout (A-Jak2 KO) mice using the Cre-loxP system with Cre expression driven by the Ap2 (also known as Fabp4) promoter.

RESULTS

Starting at 2-3 months of age, male and female A-Jak2 KO mice gradually gained more body weight than control littermates primarily due to increased adiposity. This was associated with reduced energy expenditure in A-Jak2 KO mice. In perigonadal adipose tissue, the expression of numerous genes involved in lipid metabolism was differentially regulated. In addition, adipose tissue from A-Jak2 KO mice displayed impaired lipolysis in response to isoprenaline, growth hormone and leptin stimulation, suggesting that adipose JAK2 directly modulates the lipolytic program. Impaired lipid homeostasis was also associated with disrupted adipokine secretion. Accordingly, while glucose metabolism was normal at 2 months of age, by 5-6 months of age, A-Jak2 KO mice had whole-body insulin resistance.

CONCLUSIONS/INTERPRETATION

Our results suggest that adipocyte JAK2 plays a critical role in the regulation of adipocyte biology and whole-body metabolism. Targeting of the JAK-STAT pathway could be a novel therapeutic option for the treatment of obesity and type 2 diabetes.

Oncostatin m is produced in adipose tissue and is regulated in conditions of obesity and type 2 diabetes

CONTEXT

Adipose tissue is a highly active endocrine organ that secretes many factors that affect other tissues and whole-body metabolism. Adipocytes are responsive to several glycoprotein 130 (gp130) cytokines, some of which have been targeted as potential antiobesity therapeutics.

OBJECTIVE

Oncostatin M (OSM) is a gp130 family member known to inhibit adipocyte differentiation in vitro, but its effects on other adipocyte properties are not characterized. The expression of OSM in white adipose tissue (WAT) has not been evaluated in the context of obesity. Thus, our objective was to examine the expression of adipose tissue OSM in obese animals and humans.

DESIGN

OSM expression was examined in adipose tissues from mice with diet-induced and genetic obesity and in obese humans as well as in fractionated adipose tissue from mice. Murine adipocytes were used to examine OSM receptor expression and the effects of OSM on adipocytes, including the secretion of factors such as plasminogen activator inhibitor 1 and IL-6, which are implicated in metabolic diseases.

RESULTS

OSM expression is increased in rodent and human obesity/type 2 diabetes mellitus. In humans, OSM levels correlate with body weight and insulin and are inversely correlated with glucose disposal rate as measured by hyperinsulinemic-euglycemic clamp. OSM is not produced from the adipocytes in WAT but derives from cells in the stromovascular fraction, including F4/80(+) macrophages. The specific receptor of OSM, OSM receptor-β, is expressed in adipocytes and adipose tissue and increased in both rodent models of obesity examined. OSM acts on adipocytes to induce the expression and secretion of plasminogen activator inhibitor 1 and IL-6.

CONCLUSIONS

These data indicate that WAT macrophages are a source of OSM and that OSM levels are significantly induced in murine and human obesity/type 2 diabetes mellitus. These studies suggest that OSM produced from immune cells in WAT acts in a paracrine manner on adipocytes to promote a proinflammatory phenotype in adipose tissue.

Genetic effects on DNA methylation and its potential relevance for obesity in Mexican Americans

Several studies have identified effects of genetic variation on DNA methylation patterns and associated heritability, with research primarily focused on Caucasian individuals. In this paper, we examine the evidence for genetic effects on DNA methylation in a Mexican American cohort, a population burdened by a high prevalence of obesity. Using an Illumina-based platform and following stringent quality control procedures, we assessed a total of 395 CpG sites in peripheral blood samples obtained from 183 Mexican American individuals for evidence of heritability, proximal genetic regulation and association with age, sex and obesity measures (i.e. waist circumference and body mass index). We identified 16 CpG sites (∼4%) that were significantly heritable after Bonferroni correction for multiple testing and 27 CpG sites (∼6.9%) that showed evidence of genetic effects. Six CpG sites (∼2%) were associated with age, primarily exhibiting positive relationships, including CpG sites in two genes that have been implicated in previous genome-wide methylation studies of age (FZD9 and MYOD1). In addition, we identified significant associations between three CpG sites (∼1%) and sex, including DNA methylation in CASP6, a gene that may respond to estradiol treatment, and in HSD17B12, which encodes a sex steroid hormone. Although we did not identify any significant associations between DNA methylation and the obesity measures, several nominally significant results were observed in genes related to adipogenesis, obesity, energy homeostasis and glucose homeostasis (ARHGAP9, CDKN2A, FRZB, HOXA5, JAK3, MEST, NPY, PEG3 and SMARCB1). In conclusion, we were able to replicate several findings from previous studies in our Mexican American cohort, supporting an important role for genetic effects on DNA methylation. In addition, we found a significant influence of age and sex on DNA methylation, and report on trend-level, novel associations between DNA methylation and measures of obesity.

Advances in understanding the relationship between oncostatin M and liver regeneration and liver diseases

Oncostatin M (OSM) is a pleiotropic cytokine belonging to the interleukin (IL)-6 family of cytokines. It is closely related structurally and functionally to leukemia inhibitory factor (LIF). There are two types of functional OSM receptors (OSMR): I and II. The binding of OSM to its receptors activates the JAK-STAT and MAPK signal pathways. OSM not only inhibits the proliferation of tumor cells but also participates in several physiological and pathological processes in a variety of cell types and plays key roles in the pathogenesis of multiple diseases, including regulation of inflammatory responses, stimulation of hematopoiesis, regulation of cholesterol metabolism, and induction of neurotrophic peptides. Recent studies suggest that OSM participates in liver regeneration and is closely related to the occurrence and progression of viral hepatitis, non-alcoholic fatty liver disease, liver fibrosis, and liver cancer. This article reviews recent advances in understanding the relationship between OSM and liver generation and liver diseases.

Oncostatin M is a major mediator of cardiomyocyte dedifferentiation and remodeling

Cardiomyocyte remodeling, which includes partial dedifferentiation of cardiomyocytes, is a process that occurs during both acute and chronic disease processes. Here, we demonstrate that oncostatin M (OSM) is a major mediator of cardiomyocyte dedifferentiation and remodeling during acute myocardial infarction (MI) and in chronic dilated cardiomyopathy (DCM). Patients suffering from DCM show a strong and lasting increase of OSM expression and signaling. OSM treatment induces dedifferentiation of cardiomyocytes and upregulation of stem cell markers and improves cardiac function after MI. Conversely, inhibition of OSM signaling suppresses cardiomyocyte remodeling after MI and in a mouse model of DCM, resulting in deterioration of heart function after MI but improvement of cardiac performance in DCM. We postulate that dedifferentiation of cardiomyocytes initially protects stressed hearts but fails to support cardiac structure and function upon continued activation. Manipulation of OSM signaling provides a means to control the differentiation state of cardiomyocytes and cellular plasticity.

The gp130 receptor cytokine family: regulators of adipocyte development and function

Gp130 cytokines are involved in the regulation of numerous biological processes, including hematopoiesis, immune response, inflammation, cardiovascular action, and neuronal survival. These cytokines share glycoprotein 130 as a common signal transducer in their receptor complex and typically activate STAT3. Most gp130 cytokines have paracrine or endocrine actions, and their levels can be measured in circulation in rodents and humans. In recent years, various laboratories have conducted studies to demonstrate that gp130 cytokines can modulate adipocyte development and function. Therefore, these studies suggest that some gp130 cytokines may be viable anti-obesity therapeutics. In this review, we will summarize the reported effects of gp130 cytokines on adipocyte differentiation and adipocyte function. In addition, the modulation of gp130 cytokines in conditions of obesity, insulin resistance, and Type 2 diabetes will be presented.

Zinc finger protein 467 is a novel regulator of osteoblast and adipocyte commitment

Osteoblasts and adipocytes are derived from common mesenchymal progenitor cells. The bone loss of osteoporosis is associated with altered progenitor differentiation from an osteoblastic to an adipocytic lineage. cDNA microarrays and quantitative real-time PCR (Q-PCR) were carried out in a differentiating mouse stromal osteoblastic cell line, Kusa 4b10, to identify gene targets of factors that stimulate osteoblast differentiation including parathyroid hormone (PTH) and gp130-binding cytokines, oncostatin M (OSM) and cardiotrophin-1 (CT-1). Zinc finger protein 467 (Zfp467) was rapidly down-regulated by PTH, OSM, and CT-1. Retroviral overexpression and RNA interference for Zfp467 in mouse stromal cells showed that this factor stimulated adipocyte formation and inhibited osteoblast commitment compared with controls. Regulation of adipocyte markers, including peroxisome proliferator-activated receptor (PPAR) γ, C/EBPα, adiponectin, and resistin, and late osteoblast/osteocyte markers (osteocalcin and sclerostin) by Zfp467 was confirmed by Q-PCR. Intra-tibial injection of calvarial cells transduced with retroviral Zfp467 doubled the number of marrow adipocytes in C57Bl/6 mice compared with vector control-transduced cells, providing in vivo confirmation of a pro-adipogenic role of Zfp467. Furthermore, Zfp467 transactivated a PPAR-response element reporter construct and recruited a histone deacetylase complex. Thus Zfp467 is a novel co-factor that promotes adipocyte differentiation and suppresses osteoblast differentiation. This has relevance to therapeutic interventions in osteoporosis, including PTH-based therapies currently available, and may be of relevance for the use of adipose-derived stem cells for tissue engineering.

Neuropoietin attenuates adipogenesis and induces insulin resistance in adipocytes

Recent findings have implicated gp130 receptor ligands, particularly ciliary neurotrophic factor (CNTF), as potential anti-obesity therapeutics. Neuropoietin (NP) is a recently discovered cytokine in the gp130 family that shares functional and structural features with CNTF and signals via the CNTF receptor tripartite complex comprised of CNTFRalpha, LIF receptor, and gp130. NP plays a role in the development of the nervous system, but the effects of NP on adipocytes have not been previously examined. Because CNTF exerts anti-obesogenic effects in adipocytes and NP shares the same receptor complex, we investigated the effects of NP on adipocyte development and insulin action. Using cultured 3T3-L1 adipocytes, we observed that NP has the ability to block adipogenesis in a dose- and time-dependent manner. We also observed that cultured adipocytes, as well as murine adipose tissue, are highly responsive to acute NP treatment. Rodents injected with NP had a substantial increase in STAT3 tyrosine phosphorylation and ERK 1 and 2 activation. We also observed the induction of SOCS-3 mRNA in 3T3-L1 adipocytes following NP treatment. Unlike CNTF, our studies have revealed that NP also substantially attenuates insulin-stimulated glucose uptake in 3T3-L1 adipocytes. In addition, NP blocks insulin action in adipose tissue in vivo. These observations are supported by data demonstrating that NP impairs insulin signaling via decreased activation of both IRS-1 and Akt. In summary, we have observed that both adipocytes in vitro and in vivo are highly responsive to NP, and this cytokine has the ability to affect insulin signaling in fat cells. These novel observations suggest that NP, unlike CNTF, may not be a viable obesity therapeutic.