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Glycine is one of the major neurotransmitters in the brainstem and the spinal cord. Glycine binds to and activates glycine receptors (GlyRs), increasing Cl− conductance at postsynaptic sites. This glycinergic synaptic transmission contributes to the generation of respiratory rhythm and motor patterns. Strychnine inhibits GlyR by binding to glycine-binding site, while picrotoxin blocks GlyR by binding to the channel pore. We have previously reported that bath application of strychnine to zebrafish embryos causes bilateral muscle contractions in response to tactile stimulation. To explore the drug-mediated inhibition of GlyRs, we screened a chemical library of ~ 1,000 approved drugs and pharmacologically active molecules by observing touch-evoked response of zebrafish embryos in the presence of drugs. We found that exposure of zebrafish embryos to nifedipine (an inhibitor of voltage-gated calcium channel) or niflumic acid (an inhibitor of cyclooxygenase 2) caused bilateral muscle contractions just like strychnine-treated embryos showed. We then assayed strychnine, picrotoxin, nifedipine, and niflumic acid for concentration-dependent inhibition of glycine-mediated currents of GlyRs in oocytes and calculated IC50s. The results indicate that all of them concentration-dependently inhibit GlyR in the order of strychnine > picrotoxin > nifedipine > niflumic acid.

We developed non-toxic, harmless adhesives composed of all-natural and renewable resources, of which one was composed of tannin and gelatin, which unfortunately was lacking water resistance, and the other of tannin and ε-poly-l-lysine. In this study, we analyzed the chemical structures of these adhesives by two-dimensional nuclear magnetic resonance (2D-NMR) to explain the difference in water-resistance of the two glues. The results showed that only one proton was left in the benzene ring of tannin after mixing. This suggests that the amino group of the protein was directly attached to the benzene ring by a Michael addition-type reaction, and not to the hydroxyl group. In addition, the heteronuclear multiple bond correlation spectrum of the tannin-poly-l-lysine compound indicated that the hydroxyl groups of the tannin oxidized, suggesting the improvement of its water resistance.

Yoshinone A was derived from marine algae and shown to inhibit adipogenic differentiation. The natural compound is composed of a γ-pyrone ring and a side chain and that contains two asymmetric carbons. Although their absolute configuration has been determined, there is no information available on the stereoisomers and their bioactivities. To address this question, we synthesized all four stereoisomers and measured their activities. We also prepared three more derivatives of yoshinone A and found that the stereo-configuration inside the side chain, the γ-pyrone ring, and bulkiness of the side chain all played important roles in its activity. Our findings should help to elucidate the mechanism of action of yoshinone A.

Recent synthetic adhesives can release toxic fumes, such as formaldehyde, which is a serious problem. Thus, there is an urgent need for a non-toxic adhesive for assembling furniture and for other uses indoors and in close proximity to people. Therefore, the aim of this study was to develop a non-toxic glue based on all-natural ingredients. First, we considered mixtures of plant-derived tannins and animal-derived gelatin or ovalbumin. Some compositions demonstrated a high capacity for long-term storage and strong gluing properties. However, none of them were water-resistant. Therefore, we replaced the gelatin with poly- l -lysine to improve the glues' water-resistance. In further tests, these mixtures passed the Euronorm EN314 class 1 standard. Thus, we have developed a two-component adhesive (tannin and e-poly- l -lysine) which is both harmless and environmentally friendly.

Many natural products with extraordinary chemical structures and brilliant biological activities have been obtained from marine organisms. We have investigated such fascinating bioactive molecules, exemplified by the potent marine toxin palytoxin and the antitumor molecule halichondrin B, which has been developed as the anticancer drug Halaven®, to explore novel frontiers in organic chemistry and bioscience. Working within the traditional discipline, we have sought to acquire a deeper understanding of biological phenomena. We introduce here our major work along with up-todate topics. We isolated yoshinone A from marine cyanobacteria and completed a gram-scale synthesis. Yoshinone A is a novel polyketide that inhibited the differentiation of 3T3-L1 cells into adipocytes without significant cytotoxicity. The detailed mechanisms of action will be elucidated via further experiments in vitro and in vivo. In this study, we explore the true producers of okadaic acid and halichondrin B by immunostaining of Halichondria okadai with an antibody that was prepared using these natural products as an antigen. We will analyze isolated symbionts and reveal biosynthetic pathways.

Marine cyanobacteria are known as important creators of novel natural products. From this valuable source, various bioactive compounds have been found and characterized in terms of their pharmacological and toxicological activities.1 In the previous work, we have reported on the isolation and structure determination of potent cytotoxic compounds, lyngbyacyclamide A and B;2 an inhibitor of osteoclastogenesis, biselyngbyaside;3 and a protein kinase inhibitor, bisebromoamide.4 In the recent work, we have reported the new marine γ-pyrones yoshinone A, B1 and B2 from Leptolyngbya sp., and determined their planar structures using NMR spectral analysis.5 Yoshinone A, as the major compound among them, showed inhibitory activity against the adipogenic differentiation of 3T3-L1 cells with an half maximal inhibitory concentration (IC50) value of 420 nm without cytotoxicity (IC50>50 μm). On the other hand, the yoshinone B1 and B2 showed only limited activity against 3T3-L1 cells, with higher concentrations compared with yoshinone A. Further studies of the structure–activity relationship lead us to conclude that the position of a pyrone ring and an olefin in the side chain will be important for the inhibition of adipogenic differentiation. These γ-pyrones have olefins in their side chain at positions 7 and 6 in the cases of yoshinones A and B1/B2, respectively. To express the effects on adipocyte, the olefin should not be conjugated with γ-pyrone moiety, such as yoshinone A (Figure 1). In the previous studies, kalkipyrone6 isolated from cyanobacteria, aureothin,7 and actinopyrones A and B8 isolated from streptomyces fell into the same 7-en γ-pyrones. Then, we confirmed that kalkipyrone and aureothin showed this activity, with IC50 values of 67.5 and 54.2 nm, respectively. On the basis of these data, we are focusing on the 7-en γ-pyrone (unconjugated type) compounds. These pyrones are expected to be candidates for novel lead compounds for the treatment of obesity and related diseases.9 Studies on useful tools that regulate adipocytes will contribute to the prevention and treatment of these diseases. At the present stage of our research, we have evaluated the anti-obesity activities of the 7-en γ-pyrones using in vitro and in vivo experiments. In this study, we report on the interesting properties of these pyrones.

An unprecedented bis-indole 1, a novel indole alkaloid 2, and some known indole-related compounds 3–5 have been isolated from the sponge Plakortis sp. collected from Zampa in Okinawa. Their structures were elucidated by spectroscopic analysis. These metabolites showed cytotoxic activity against P388 leukemia and B16 melanoma cells.

Three novel compounds, yoshinones A, B1, and B2, were isolated from the marine cyanobacterium Leptolyngbya sp., and their structures were elucidated by NMR spectral analysis. Yoshinone A, but not yoshinone B1 or B2, inhibited the differentiation of 3T3-L1 cells into adipocytes. In addition, yoshinone A did not exhibit cytotoxicity, suggesting that yoshinone A may be useful in studies on the treatment of obesity.

SummaryA small-molecule fluorescent probe specific for human pluripotent stem cells would serve as a useful tool for basic cell biology research and stem cell therapy. Screening of fluorescent chemical libraries with human induced pluripotent stem cells (iPSCs) and subsequent evaluation of hit molecules identified a fluorescent compound (Kyoto probe 1 [KP-1]) that selectively labels human pluripotent stem cells. Our analyses indicated that the selectivity results primarily from a distinct expression pattern of ABC transporters in human pluripotent stem cells and from the transporter selectivity of KP-1. Expression of ABCB1 (MDR1) and ABCG2 (BCRP), both of which cause the efflux of KP-1, is repressed in human pluripotent stem cells. Although KP-1, like other pluripotent markers, is not absolutely specific for pluripotent stem cells, the identified chemical probe may be used in conjunction with other reagents.

Adhesamine is an organic small molecule that promotes adhesion and growth of cultured human cells by binding selectively to heparan sulfate on the cell surface. The present study combined chemical, physicochemical, and cell biological experiments, using adhesamine and its analogues, to examine the mechanism by which this dumbbell-shaped, non-peptidic molecule induces physiologically relevant cell adhesion. The results suggest that multiple adhesamine molecules cooperatively bind to heparan sulfate and induce its assembly, promoting clustering of heparan sulfate-bound syndecan-4 on the cell surface. A pilot study showed that adhesamine improved the viability and attachment of transplanted cells in mice. Further studies of adhesamine and other small molecules could lead to the design of assembly-inducing molecules for use in cell biology and cell therapy.

The novel 9,11-secosteroid, haebaruol, was isolated from the soft coral Clavularia sp. collected from the Ishigaki Island, Okinawa, Japan. The planar structure of haebaruol was elucidated by NMR sp...

In response to amino acid starvation, autophagy mediates the lysosome-dependent turnover of cytosolic components via autophagosome formation. Despite advances in understanding the molecular basis of autophagy process, the regulatory mechanism remains unclear. Here, we show that repression of protein synthesis stabilizes the messenger RNAs of specific autophagy-related (ATG) genes, increasing their respective half-lives. Further analysis indicated that the stabilization process is attributable to the coding region of the mRNAs. The results suggest a novel mechanism of autophagy regulation by post-transcriptional mRNA stabilization, in which repression of protein synthesis plays a direct role to sustain the autophagy process.

Signal transducer and activator of transcription 6 (STAT6), which plays a critical role in immune responses, is activated by interleukin-4 (IL-4). Activity of STAT family members is regulated primarily by tyrosine phosphorylations and possibly also by serine phosphorylations. Here, we report a previously undescribed serine phosphorylation of STAT6, which is activated by cell stress or by the pro-inflammatory cytokine, interleukin-1β (IL-1β). Our analyses suggest that Ser-707 is phosphorylated by c-Jun N-terminal kinase (JNK). Phosphorylation decreases the DNA binding ability of IL-4-stimulated STAT6, thereby inhibiting the transcription of STAT6-responsive genes. Inactivation of STAT6 by JNK-dependent Ser-707 phosphorylation may be one mechanism of controlling the balance between IL-1β and IL-4 signals.

Ternatin, a cyclic heptapeptide derived from mushroom, strongly inhibits fat accumulation in 3T3-L1 adipocytes. However, its mechanism of action remains unclear. In this Letter, we designed, synthesized, and evaluated its derivatives for use as molecular probes to isolate its target protein. Finally, we successfully established a pair of ternatin molecular probes.

Received: July 9, 2010 , Accepted: July 30, 2010 , Published: August 6, 2010 // The membrane-anchored matrix metalloproteinase-regulator RECK is often downregulated in various types of cancers; the levels of residual RECK in resected tumors often correlate with better prognosis. Forced expression of RECK in cancer cells suppresses tumor angiogenesis, invasion, and metastasis in xenograft models. RECK is therefore a promising marker for benignancy and a potential effector in cancer therapy. We established a cell line containing two transgene systems: (1) the secreted alkaline phosphatase (SEAP) gene fused to Reck promoter and (2) the HRAS12V oncogene driven by the Tet-off promoter system. This cell line exhibits transformed phenotype in regular medium and flat morphology with increased SEAP activity in the presence of doxycycline, allowing the assessment of RECK-inducing activity of chemicals in the contexts of both transformed and untransformed cells. Our pilot experiments with 880 known bioactive compounds detected 34 compounds that activate RECK promoter; among these, 10 were authentic anticancer drugs. Four selected compounds up-regulated endogenous RECK protein in several human cancer cell lines. The top-ranking compound, disulfiram, strongly suppressed spontaneous lung-metastasis of human fibrosarcoma cells in nude mice. Our data demonstrate the value of this screen in discovering effective cancer therapeutics.

Identification of protein targets of bioactive small molecules has been a technical hurdle of chemical genetics. Here we report a polyproline-rod approach to isolating protein targets of small molecules from cell lysates. The results indicate that insertion of a long, rigid polyproline helix between a small-molecule bait and a biotin tag boosts the capacity of affinity purification and thereby permits isolation of low-abundance or low-affinity proteins. In the course of the proof-of-concept experiments, we isolated glyoxalase 1 (GLO1) as a new target of indomethacin, a widely used antiinflammatory drug. Molecular biological experiments suggest that inhibition of GLO1 enzyme activity is related to the clinically recognized beneficial side effects of the indomethacin family of nonsteroidal antiinflammatory drugs.

Yoshinone A (I) and the diastereomeric yoshinones B1 and B2 (II) are evaluated towards their adipogenic differentiation of 3T3-L1 cells with (I) showing potential as a novel lead compound for treatment of obesity.

Development of synthetic molecules that provide external control over the transcription of a given gene represents a challenge in medicinal and bioorganic chemistry. Here we report design and analysis of wrenchnolol, a wrench-shaped synthetic molecule that impairs the transcription of the Her2 oncogene by disrupting association of transcription factor ESX with its coactivator Sur-2. The "jaw" part of the compound mimics the alpha-helical interface of the activation domain of ESX, and the "handle" region accepts chemical modifications for a range of analysis. A water-soluble handle permitted NMR study in aqueous solution; a biotinylated handle verified the selectivity of the interaction, and a fluorescent handle confirmed the cell permeability of the compound. The case study of wrenchnolol foreshadows the promise and the challenge of targeting protein-protein interactions in the nucleus and may lead to the development of unique synthetic modulators of gene transcription.

An important step in the postgenomic drug discovery is the construction of high quality chemical libraries that generate bioactive molecules at high rates. Here we report a cell-based approach to composing a focused library of biologically active compounds. A collection of bioactive non-cytotoxic chemicals was identified from a divergent library through the effects on the insulin-induced adipogenesis of 3T3-L1 cells, one of the most drastic and sensitive morphological alterations in cultured mammalian cells. The resulting focused library amply contained unique compounds with a broad range of pharmacological effects, including glucose-uptake enhancement, cytokine inhibition, osteogenesis stimulation, and selective suppression of cancer cells. Adipogenesis profiling of organic compounds generates a focused chemical library for multiple biological effects that are seemingly unrelated to adipogenesis, just as genetic screens with the morphology of fly eyes identify oncogenes and neurodegenerative genes.

A new diterpenoid, jolkinolide F (1), was isolated from roots of Euphorbia jolkinii. The planar structure of 1 was elucidated by spectroscopic analysis, and its stereochemistry was determined by NO...

Small heat shock proteins (sHsps) have been suggested to act as molecular chaperones for many kinds of substrates and have protective roles in cells exposed to external stresses. Unlike other major Hsps such as Hsp70 and Hsp90, expression of many vertebrate sHsps is restricted to the muscle tissues and/or eye lens. Among the sHsps, the heat-inducible human Hsp27 (hHsp27) homologue is believed to be expressed ubiquitously in various cell types. Here, we distinguished the chicken homologue of hHsp27 (cHsp24) from the chicken major heat-inducible protein of molecular size 25 kDa (cHsp25). cHsp25 is not expressed in the absence of stress, but is highly expressed after hyperthermia in all tissues of developing embryos. In contrast, expression of cHsp24 is restricted to some specific tissues even in the presence of stress. Thus, cHsp25 is the first member of the sHsps in vertebrates the expression of which is ubiquitous in tissues exposed to external stresses similar to Hsp70.

The novel 9,11-secosteroid, haebaruol, was isolated from the soft coral Clavularia sp. collected from the Ishigaki Island, Okinawa, Japan. The planar structure of haebaruol was elucidated by NMR sp...

Avian cells express three heat shock transcription factor (HSF) genes corresponding to a novel factor, HSF3, and homologs of mouse and human HSF1 and HSF2. Analysis of the biochemical and cell biological properties of these HSFs reveals that HSF3 has properties in common with both HSF1 and HSF2 and yet has features which are distinct from both. HSF3 is constitutively expressed in the erythroblast cell line HD6, the lymphoblast cell line MSB, and embryo fibroblasts, and yet its DNA-binding activity is induced only upon exposure of HD6 cells to heat shock. Acquisition of HSF3 DNA-binding activity in HD6 cells is accompanied by oligomerization from a non-DNA-binding dimer to a DNA-binding trimer, whereas the effect of heat shock on HSF1 is oligomerization of an inert monomer to a DNA-binding trimer. Induction of HSF3 DNA-binding activity is delayed compared with that of HSF1. As occurs for HSF1, heat shock leads to the translocation of HSF3 to the nucleus. HSF exhibits the properties of a transcriptional activator, as judged from the stimulatory activity of transiently overexpressed HSF3 measured by using a heat shock element-containing reporter construct and as independently assayed by the activity of a chimeric GAL4-HSF3 protein on a GAL4 reporter construct. These results reveal that HSF3 is negatively regulated in avian cells and acquires DNA-binding activity in certain cells upon heat shock.

In response to amino acid starvation, autophagy mediates the lysosome-dependent turnover of cytosolic components via autophagosome formation. Despite advances in understanding the molecular basis of autophagy process, the regulatory mechanism remains unclear. Here, we show that repression of protein synthesis stabilizes the messenger RNAs of specific autophagy-related (ATG) genes, increasing their respective half-lives. Further analysis indicated that the stabilization process is attributable to the coding region of the mRNAs. The results suggest a novel mechanism of autophagy regulation by post-transcriptional mRNA stabilization, in which repression of protein synthesis plays a direct role to sustain the autophagy process.

A method was developed that uses small molecules as fluorescent probes to detect specific mRNAs. In this approach, the fluorescence of fluorophore–quencher conjugates is restored by the binding of an mRNA aptamer tag to the quencher segment of the molecules. The method allows real-time detection of mRNA transcripts in vitro.

SummarySterol regulatory element binding proteins (SREBPs) are transcription factors that activate transcription of the genes involved in cholesterol and fatty acid biosynthesis. In the present study, we show that a small synthetic molecule we previously discovered to block adipogenesis is an inhibitor of the SREBP activation. The diarylthiazole derivative, now called fatostatin, impairs the activation process of SREBPs, thereby decreasing the transcription of lipogenic genes in cells. Our analysis suggests that fatostatin inhibits the ER-Golgi translocation of SREBPs through binding to their escort protein, the SREBP cleavage-activating protein (SCAP), at a distinct site from the sterol-binding domain. Fatostatin blocked increases in body weight, blood glucose, and hepatic fat accumulation in obese ob/ob mice, even under uncontrolled food intake. Fatostatin may serve as a tool for gaining further insights into the regulation of SREBP.

Regulation of gene expression by transcription factors touches many aspects of eukaryotic biology, and its systematic, external control by organic molecules represents a challenge in chemistry. Here we report the design of a completely organic, nonpeptidic compound that mimics a transcription factor. The design takes advantage of the specific DNA-binding affinity of a hairpin polyamide molecule and the ability of wrenchnolol to bind to the Sur-2 subunit of human mediator complex. The hybrid compound of these two molecules activates transcription of a reporter gene in vitro in a promoter-dependent manner through simultaneous contacts with DNA and Sur-2. Our results indicate that it is possible to generate a transcription factor out of nonpeptidic components.

Development of synthetic molecules that provide external control over the transcription of a given gene represents a challenge in medicinal and bioorganic chemistry. Here we report design and analysis of wrenchnolol, a wrench-shaped synthetic molecule that impairs the transcription of the Her2 oncogene by disrupting association of transcription factor ESX with its coactivator Sur-2. The "jaw" part of the compound mimics the alpha-helical interface of the activation domain of ESX, and the "handle" region accepts chemical modifications for a range of analysis. A water-soluble handle permitted NMR study in aqueous solution; a biotinylated handle verified the selectivity of the interaction, and a fluorescent handle confirmed the cell permeability of the compound. The case study of wrenchnolol foreshadows the promise and the challenge of targeting protein-protein interactions in the nucleus and may lead to the development of unique synthetic modulators of gene transcription.

Previous experiments have shown that STAT-induced STAT inhibitor-1 (SSI-1; also named suppressors of cytokine signaling-1 (SOCS-1) or Janus kinase binding protein) is predominantly expressed in lymphoid organs and functions in vitro as a negative regulator of cytokine signaling. To determine the function of SOCS-1 in vivo, we generated SSI-1 transgenic mice using the lck proximal promoter that drives transgene expression in T cell lineage. In thymocytes expressing SSI-1 transgene, tyrosine phosphorylation of STATs in response to cytokines such as IFN-γ, IL-6, and IL-7 was inhibited, suggesting that SSI-1 suppresses cytokine signaling in primary lymphocytes. In addition, lck-SSI-1 transgenic mice showed a reduction in the number of thymocytes as a result of the developmental blocking during triple-negative stage. They also exhibited a relative increase in the percentage of CD4+ T cells, a reduction in the number of γδ T cells, as well as the spontaneous activation and increased apoptosis of peripheral T cells. Thus, enforced expression of SSI-1 disturbs the development of thymocytes and the homeostasis of peripheral T cells. All these features of lck-SSI-1 transgenic mice strikingly resemble the phenotype of mice lacking common γ-chain or Janus kinase-3, suggesting that transgene-derived SSI-1 inhibits the functions of common γ-chain-using cytokines. Taken together, these results suggest that SSI-1 can also inhibit a wide variety of cytokines in vivo.

Heat-shock proteins and molecular chaperones are involved in various cellular metabolic processes including protein synthesis and degradation. These expressions are elevated at the level of transcription by the accumulation of abnormal proteins when these metabolic processes are disturbed. Recent works suggest the induction of heat-shock proteins by the inhibiton of proteasome. To elucidate the mechanism of this induction, we examined the activation of heat-shock transcription factors by proteasome inhibitors in avian cells. Activation of the two heat-shock-inducible factors, HSF1 and HSF3, was produced by the treatment of cells with proteasome inhibitors. This activation was not produced by treatment with various other protease inhibitors. The HSF activation by proteasome inhibitors was completely blocked in the presence of the protein synthesis inhibitor cycloheximide. Unexpectedly, the development-related factor HSF2 was also activated by proteasome inhibitors, with an increase in its protein level. These results suggest that the ubiqutin-proteasome pathway may regulate all of the three HSFs by controlling the level of some regulatory factor for HSF or HSF itself, as well as controlling abnormal proteins.

External control of gene expression by small synthetic molecules represents a challenge in chemistry. Here we discuss the synthetic aspects of small molecule transcription factor mimics including a molecule we call STF1 (1). STF1 stimulates the transcription of a reporter gene controlled by specific DNA elements and behaves just as a naturally occurring transcription factor. However, STF1 had limited cell permeability, even though the hairpin-polyamide-FITC conjugate and the wrenchnolol (2) are cell permeable as separate compounds. Systematic synthetic exploration of STF1 analogs (STFs), by optimizing the physical properties of the molecule, is expected to increase its cell permeability for biological studies.

Heatshocktranscriptionfactors(HSFs)mediatetheinducibletranscriptionalresponseofgenesthatencode heat shock proteins and molecular chaperones. In vertebrates, three relatedHSFgenes (HSF1to -3) and the respective gene products (HSFs) have been characterized. We report the cloning and characterization of human HSF4 (hHSF4), a novel member of the hHSF family that shares properties with other members of the HSF family yet appears to be functionally distinct. hHSF4 lacks the carboxyl-terminal hydrophobic repeat which is shared among all vertebrate HSFs and has been suggested to be involved in the negative regulation of DNA binding activity. hHSF4 is preferentially expressed in the human heart, brain, skeletal muscle, and pancreas. Transient transfection of hHSF4 in HeLa cells, which do not express hHSF4, results in a constitutively active DNA binding trimer which, unlike other members of the HSF family, lacks the properties of a transcriptional activator. Constitutive overexpression of hHSF4 in HeLa cells results in reduced expression of the endogenous hsp70, hsp90, and hsp27 genes. hHSF4 represents a novel hHSF that exhibits tissue-specific expression and functions to repress the expression of genes encoding heat shock proteins and molecular chaperones. The inducible transcription of heat shock genes is mediated by members of a family of heat shock transcription factors (HSFs) which share common properties. The vertebrate HSFs are negatively regulated for DNA binding and transactivation and become activated in response to heat shock and other forms of environmental and chemical stress to form transcriptionally active trimers. An unexpectedfinding during the cloning of theHSFgenes from plants and vertebrates was the identification of a HSF multigene family. At least threeHSFgenes have been isolated from the human, mouse, chicken, and tomato genomes, whereas only a single functional HSF gene has been charac

A large collection of bioactive compounds with diverse biological effects can be used as probes to elucidate new biological mechanisms that influence a particular cellular process. Here we analyze the effects of 880 well-known small-molecule bioactives or drugs on the insulin-induced adipogenesis of 3T3-L1 fibroblasts, a cell-culture model of fat cell differentiation. Our screen identified 86 compounds as modulators of the adipogenic differentiation of 3T3-L1 cells. Examination of their chemical and pharmacological information revealed that antihistamine drugs with distinct chemical scaffolds inhibit differentiation. Histamine H1 receptor is expressed in 3T3-L1 cells, and its knockdown by small interfering RNA impaired the insulin-induced adipogenic differentiation. Histamine receptors and histamine-like biogenic amines may play a role in inducing adipogenesis in response to insulin.

Suppressor of cytokine signaling-1 (SOCS-1), also known as STAT-induced STAT inhibitor-1 (SSI-1), is a negative feedback molecule for cytokine signaling, and its in vivo deletion induces fulminant hepatitis. However, elimination of the STAT1 or STAT6 gene or deletion of NKT cells substantially prevented severe hepatitis in SOCS-1-deficient mice, while administration of IFN-gamma and IL-4 accelerated its development. SOCS-1 deficiency not only sustained IFN-gamma/IL-4 signaling but also eliminated the cross-inhibitory action of IFN-gamma on IL-4 signaling. These results suggest that SOCS-1 deficiency-induced persistent activation of STAT1 and STAT6, which would be inhibited by SOCS-1 under normal conditions, may induce abnormal activation of NKT cells, thus leading to lethal pathological changes in SOCS-1-deficient mice.