TAZ deficiency exacerbates psoriatic pathogenesis by increasing the histamine-releasing factor.

BACKGROUND: Transcriptional coactivator with PDZ-biding motif (TAZ) is widely expressed in most tissues and interacts with several transcription factors to regulate cell proliferation, differentiation, and death, thereby influencing organ development and size control. However, very little is known about the function of TAZ in the immune system and its association with inflammatory skin diseases, so we investigated the role of TAZ in the pathogenesis of psoriasis. RESULTS: Interestingly, TAZ was expressed in mast cells associated, particularly in lysosomes, and co-localized with histamine-releasing factor (HRF). TAZ deficiency promoted mast cell maturation and increased HRF expression and secretion by mast cells. The upregulation of HRF in TAZ deficiency was not due to increased transcription but to protein stabilization, and TAZ restoration into TAZ-deficient cells reduced HRF protein. Interestingly, imiquimod (IMQ)-induced psoriasis, in which HRF serves as a major pro-inflammatory factor, was more severe in TAZ KO mice than in WT control. HRF expression and secretion were increased by IMQ treatment and were more pronounced in TAZ KO mice treated with IMQ. CONCLUSIONS: Thus, as HRF expression was stabilized in TAZ KO mice, psoriatic pathogenesis progressed more rapidly, indicating that TAZ plays an important role in preventing psoriasis by regulating HRF protein stability.

TAZ deficiency impairs the autophagy-lysosomal pathway through NRF2 dysregulation and lysosomal dysfunction.

Transcriptional coactivator with a PDZ-binding motif (TAZ) plays a key role in normal tissue homeostasis and tumorigenesis through interaction with several transcription factors. In particular, TAZ deficiency causes abnormal alveolarization and emphysema, and persistent TAZ overexpression contributes to lung cancer and pulmonary fibrosis, suggesting the possibility of a complex mechanism of TAZ function. Recent studies suggest that nuclear factor erythroid 2-related factor 2 (NRF2), an antioxidant defense system, induces TAZ expression during tumorigenesis and that TAZ also activates the NRF2-mediated antioxidant pathway. We thus thought to elucidate the cross-regulation of TAZ and NRF2 and the underlying molecular mechanisms and functions. TAZ directly interacted with NRF2 through the N-terminal domain and suppressed the transcriptional activity of NRF2 by preventing NRF2 from binding to DNA. In addition, the return of NRF2 to basal levels after signaling was inhibited in TAZ deficiency, resulting in sustained nuclear NRF2 levels and aberrantly increased expression of NRF2 targets. TAZ deficiency failed to modulate optimal NRF2 signaling and concomitantly impaired lysosomal acidification and lysosomal enzyme function, accumulating the abnormal autophagy vesicles and reactive oxygen species and causing protein oxidation and cellular damage in the lungs. TAZ restoration to TAZ deficiency normalized dysregulated NRF2 signaling and aberrant lysosomal function and triggered the normal autophagy-lysosomal pathway. Therefore, TAZ is indispensable for the optimal regulation of NRF2-mediated autophagy-lysosomal pathways and for preventing pulmonary damage caused by oxidative stress and oxidized proteins.

TAZ promotes PDX1-mediated insulinogenesis.

Transcriptional co-activator with PDZ-binding motif (TAZ) is a key mediator of the Hippo signaling pathway and regulates structural and functional homeostasis in various tissues. TAZ activation is associated with the development of pancreatic cancer in humans, but it is unclear whether TAZ directly affects the structure and function of the pancreas. So we sought to identify the TAZ function in the normal pancreas. TAZ defect caused structural changes in the pancreas, particularly islet cell shrinkage and decreased insulin production and ß-cell markers expression, leading to hyperglycemia. Interestingly, TAZ physically interacted with the pancreatic and duodenal homeobox 1 (PDX1), a key insulin transcription factor, through the N-terminal domain of TAZ and the homeodomain of PDX1. TAZ deficiency decreased the DNA-binding and transcriptional activity of PDX1, whereas TAZ overexpression promoted PDX1 activity and increased insulin production even in a low glucose environment. Indeed, high glucose increased insulin production by turning off the Hippo pathway and inducing TAZ activation in pancreatic ß-cells. Ectopic TAZ overexpression along with PDX1 activation was sufficient to produce insulin in non-ß-cells. TAZ deficiency impaired the mesenchymal stem cell differentiation into insulin-producing cells (IPCs), whereas TAZ recovery restored normal IPCs differentiation. Compared to WT control, body weight increased in TAZ-deficient mice with age and even more with a high-fat diet (HFD). TAZ deficiency significantly exacerbated HFD-induced glucose intolerance and insulin resistance. Therefore, TAZ deficiency impaired pancreatic insulin production, causing hyperglycemia and exacerbating HFD-induced insulin resistance, indicating that TAZ may have a beneficial effect in treating insulin deficiency in diabetes.

Amodiaquine promotes testosterone production and de novo synthesis of cholesterol and triglycerides in Leydig cells.

Testosterone is a hormone essential for male reproductive function. It is produced primarily by Leydig cells in the testicle through activation of steroidogenic acute regulatory protein and a series of steroidogenic enzymes, including a cytochrome P450 side-chain cleavage enzyme (cytochome P450 family 11 subfamily A member 1), 17α-hydroxylase (cytochrome P450 family 17 subfamily A member 1), and 3ß-hydroxysteroid dehydrogenase. These steroidogenic enzymes are mainly regulated at the transcriptional level, and their expression is increased by the nuclear receptor 4A1. However, the effect on Leydig cell function of a small molecule-activating ligand, amodiaquine (AQ), is unknown. We found that AQ effectively and significantly increased testosterone production in TM3 and primary Leydig cells through enhanced expression of steroidogenic acute regulatory protein, cytochome P450 family 11 subfamily A member 1, cytochrome P450 family 17 subfamily A member 1, and 3ß-hydroxysteroid dehydrogenase. Concurrently, AQ dose-dependently increased the expression of 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in the cholesterol synthesis pathway, through induction of the transcriptional and DNA-binding activities of nuclear receptor 4A1, contributing to increased cholesterol synthesis in Leydig cells. Furthermore, AQ increased the expression of fatty acid synthase and diacylglycerol acyltransferase and potentiated de novo synthesis of fatty acids and triglycerides (TGs). Lipidomics profiling further confirmed a significant elevation of intracellular lipid and TG levels by AQ in Leydig cells. These results demonstrated that AQ effectively promotes testosterone production and de novo synthesis of cholesterol and TG in Leydig cells, indicating that AQ may be beneficial for treating patients with Leydig cell dysfunction and subsequent testosterone deficiency.

Dimerized Translationally Controlled Tumor Protein-Binding Peptide 2 Attenuates Systemic Anaphylactic Reactions Through Direct Suppression of Mast Cell Degranulation.

Dimerized translationally controlled tumor protein (dTCTP) amplifies allergic responses through activation of several types of immune cells and release of inflammatory mediators. In particular, dTCTP plays an important role in histamine release by triggering mast cells and has been proposed as a target in the treatment of allergic diseases. dTCTP-binding peptide 2 (dTBP2) is known to attenuate severe allergic rhinitis and asthma through inhibition of dTCTP activity on airway epithelial cells and T cells; however, it is unclear whether dTBP2 affects mast cell function and mast cell disease. In this study, we explored the effects of dTBP2 on mast cell degranulation and allergen-induced anaphylactic reactions. We found that bacterial product lipopolysaccharide increased the expression of dTCTP in mast cells and rapidly released dTCTP by the mast cell stimulator compound 48/80. Interestingly, the released dTCTP further promoted mast cell degranulation in an autocrine activation manner and increased calcium mobilization in mast cells, which is essential for degranulation. Furthermore, dTBP2 directly and dose-dependently inhibited in vitro mast cell degranulation enhanced by compound 48/80, suggesting a direct and potent anti-anaphylactic activity of dTBP2. dTBP2 also significantly suppressed the dTCTP-induced degranulation and histamine release through inhibition of the p38 MAPK signaling pathway and suppression of lysosomal expansion and calcium mobilization in mast cells. More importantly, in vivo administration of dTBP2 decreased mortality and significantly attenuated histamine release and inflammatory cytokine production in compound 48/80-induced systemic anaphylactic reactions. These results suggest that dTBP2 is beneficial for the control of anaphylaxis with increased dTCTP.

HSPB1 inhibitor J2 attenuates lung inflammation through direct modulation of Ym1 production and paracrine signaling.

Heat shock protein beta-1 (HSPB1) is a multifaceted protein that controls cellular stress, modulates cell differentiation and development, and inhibits apoptosis of cancer cells. Increased HSPB1 expression is highly associated with poor outcomes in lung cancer by enhancing cell migration and invasion; therefore, targeting HSPB1 may be a promising therapeutic for lung cancer and fibrosis. Although the HSPB1 inhibitor J2 has been reported to exhibit potent antifibrotic effects, it remains unclear whether and how J2 directly modulates inflammatory immune responses in pulmonary fibrosis. In this study, we found that J2 potently attenuated irradiation or bleomycin-induced pulmonary fibrosis by significantly inhibiting the infiltration and activation of T cells and macrophages. J2 inhibited T-cell proliferation and subsequently suppressed T helper cell development. Although there was no significant effect of J2 on cell proliferation of M1 and M2 macrophages, J2 specifically increased the expression of Ym1 in M2 macrophages without affecting the expression of other M2 markers. Interestingly, J2 increased lysosomal degradation of HSPB1 and inhibited HSPB1-induced repression of signal transducer and activator of transcription 6 (STAT6), which simultaneously increased STAT6 and Ym1 expression. Ym1 production and secretion by J2-treated M2 macrophages substantially decreased IL-8 production by airway epithelial cells in vitro and in vivo, resulting in attenuation of airway inflammation. Taken together, we suggest that J2 has potential as a therapeutic agent for pulmonary fibrosis with increased HSPB1 expression through direct immune suppression by Ym1 production by M2 macrophages as well as T-cell suppression.

dTBP2 attenuates severe airway inflammation by blocking inflammatory cellular network mediated by dTCTP.

Dimeric translationally controlled tumor protein (dTCTP), also known as histamine-releasing factor, amplifies allergic responses and its production has been shown to increase in inflammatory diseases such as allergic asthma. Despite the critical role of dTCTP in allergic inflammation, little is known about its production pathways, associated cellular networks, and underlying molecular mechanisms. In this study, we explored the dTCTP-mediated inflammatory networks and molecular mechanisms of dTCTP associated with lipopolysaccharides (LPS)-induced severe asthma. LPS stimulation increased dTCTP production by mast cells and dTCTP secretion during degranulation, and extracellular dTCTP subsequently increased the production of pro-inflammatory molecules, including IL-8, by airway epithelial cells without affecting mast cell activation. Furthermore, dimeric TCTP-binding peptide 2 (dTBP2), a dTCTP inhibitor peptide, selectively blocked the dTCTP-mediated signaling network from mast cells to epithelial cells and decreased IL-8 production through IkB induction and nuclear p65 export in airway epithelial cells. More importantly, dTBP2 efficiently attenuated LPS-induced severe airway inflammation in vivo, resulting in decreased immune cell infiltration and IL-17 production and attenuated dTCTP secretion. These results suggest that dTCTP produced by mast cells exacerbates airway inflammation through activation of airway epithelial cells in a paracrine signaling manner, and that dTBP2 is beneficial in the treatment of severe airway inflammation by blocking the dTCTP-mediated inflammatory cellular network.

Post-Translational Modifications in Transcription Factors that Determine T Helper Cell Differentiation.

CD4+ T helper (Th) cells play a crucial role in the modulation of innate and adaptive immune responses through the differentiation of Th precursor cells into several subsets, including Th1, Th2, Th17, and regulatory T (Treg) cells. Effector Th and Treg cells are distinguished by the production of signature cytokines and are important for eliminating intracellular and extracellular pathogens and maintaining immune homeostasis. Stimulation of naïve Th cells by T cell receptor and specific cytokines activates master transcription factors and induces lineage specification during the differentiation of Th cells. The master transcription factors directly activate the transcription of signature cytokine genes and also undergo post-translational modifications to fine-tune cytokine production and maintain immune balance through cross-regulation with each other. This review highlights the post-translational modifications of master transcription factors that control the differentiation of effector Th and Treg cells and provides additional insights on the immune regulation mediated by protein arginine-modifying enzymes in effector Th cells.

The essential role of TAZ in normal tissue homeostasis.

Transcriptional coactivator with PDZ-binding motif (TAZ) has been extensively characterized in organ development, tissue regeneration, and tumor progression. In particular, TAZ functions as a Hippo mediator that regulates organ size, tumor growth and migration. It is highly expressed in various types of human cancer, and has been reported to be associated with tumor metastasis and poor outcomes in cancer patients, suggesting that TAZ is an oncogenic regulator. Yes-associated protein (YAP) has 60% similarity in amino acid sequence to TAZ and plays redundant roles with TAZ in the regulation of cell proliferation and migration of cancer cells. Therefore, TAZ and YAP, which are encoded by paralogous genes, are referred to as TAZ/YAP and are suggested to be functionally equivalent. Despite its similarity to YAP, TAZ can be clearly distinguished from YAP based on its genetic, structural, and functional aspects. In addition, targeting superabundant TAZ can be a promising therapeutic strategy for cancer treatment; however, persistent TAZ inactivation may cause failure of tissue homeostatic control. This review focuses primarily on TAZ, not YAP, discusses its structural features and physiological functions in the regulation of tissue homeostasis, and provides new insights into the drug development targeting TAZ to control reproductive and musculoskeletal disorders.

Transcriptional coactivator with PDZ-binding motif suppresses the expression of steroidogenic enzymes by nuclear receptor 4 A1 in Leydig cells.

Transcriptional coactivator with PDZ-binding motif (TAZ) plays crucial role in maintaining testicular structure and function via regulation of senescence of spermatogenic cells. However, it remains unclear whether TAZ is involved in testosterone biosynthesis in testicular Leydig cells. We found that TAZ deficiency caused aberrant Leydig cell expansion and increased lipid droplet formation, which was significantly associated with increased lipogenic enzyme expression. Additionally, the expression of key steroidogenic enzymes, including steroidogenic acute regulatory protein, cytochrome P450 (CYP) 11A1, CYP17A1, and 3ß-hydroxysteroid dehydrogenase, was greatly increased in TAZ-deficient testes and primary Leydig cells. Interestingly, the transcriptional activity of nuclear receptor 4 A1 (NR4A1) was dramatically suppressed by TAZ; however, the protein expression and the subcellular localization of NR4A1 were not affected by TAZ. TAZ directly associated with the N-terminal region of NR4A1 and substantially suppressed its DNA-binding and transcriptional activities. Stable expression of TAZ in the mouse Leydig TM3 cell line decreased the expression of key steroidogenic enzymes, whereas knockdown of endogenous TAZ in TM3 cells increased transcripts of steroidogenic genes induced by NR4A1. Consistently, testosterone production was enhanced within TAZ-deficient Leydig cells. However, TAZ deficiency resulted in decreased testosterone secretion caused by dysfunctional mitochondria and lysosomes. Therefore, TAZ plays essential role in NR4A1-induced steroidogenic enzyme expression and testosterone production in Leydig cells.

Highly Efficient and Stable Removal of Arsenic by Live Cell Fabricated Magnetic Nanoparticles.

As concerns about public health and environmental problems regarding contamination by toxic substances increase worldwide, the development of a highly effective and specific treatment method is imperative. Although physicochemical arsenic treatment methods have been developed, microbial in vivo remediation processes using live cell fabricated nanoparticles have not yet been reported. Herein, we report the development of magnetic iron nanoparticles immobilized an extremophilic microorganism, Deinococcus radiodurans R1, capable of removing toxic arsenic species. First, in vivo synthesis of magnetic iron nanoparticles was successfully achieved with the D. radiodurans R1 strain and characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), dynamic light scattering (DLS), zeta-potential, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. Second, the maximum removal capacity of the magnetic iron nanoparticle-immobilized D. radiodurans R1 strain (DR-FeNPs) for arsenic [As(V)] was evaluated under the optimized conditions. Finally, the removal capacity of DR-FeNPs in the presence of various competitive anions was also investigated to simulate the practical application. More than 98% of As(V) was efficiently removed by DR-FeNPs within 1 h, and the removal efficiency was stably maintained for up to 32 h (98.97%). Furthermore, the possibility of recovery of DR-FeNPs after use was also suggested using magnets as a proof-of-concept.

Novel anti-adipogenic activity of anti-malarial amodiaquine through suppression of PPARγ activity.

Amodiaquine (AQ) was developed as a selective drug against Plasmodium falciparum malaria infection and has received increasing attention as a therapeutic agent for the treatment of rheumatoid arthritis, Parkinson's disease, and cancer due to its anti-inflammatory, anti-proliferative, and autophagic-lysosomal blockade properties. As autophagy activation is involved in promoting adipogenic differentiation, we examined whether anti-autophagic AQ affected adipocyte differentiation of 3T3-L1 pre-adipocytes. AQ dose-dependently and significantly suppressed adipocyte differentiation in conjunction with decreases in lipid droplet formation and expression of adipogenic markers including adiponectin, adipocyte fatty acid-binding protein 2 (aP2), resistin, and leptin. Although peroxisome proliferator-activated receptor γ (PPARγ) decreases by inhibition of autophagy, AQ treatment did not induce PPARγ degradation despite the suppression of autophagolysosomal degradation. Instead, AQ suppressed the PPARγ activity to transcriptionally activate the aP2 gene transcription through the selective prevention of nuclear localization of PPARγ. These results demonstrated the novel anti-adipogenic activity of AQ and identified its underlying mechanism that AQ suppressed adipogenic gene expression and lipid formation by inhibiting nuclear localization of PPARγ in an autophagy-independent manner. AQ is recommended as a safe and effective anti-obesity drug for controlling overweight and obesity.

CBMG, a novel derivative of mansonone G suppresses adipocyte differentiation via suppression of PPARγ activity.

Mansorins and mansonones have been isolated from Mansonia gagei heartwoods, a traditional herbal medicine used to treat heart failure, and characterized to have anti-oxidant, anti-bacterial, anti-tumor, and anti-estrogenic activities. However, there is as yet no information on their effects on adipogenesis and lipid storage associated with heart disease. In this study, we investigated the effects of naturally occurring compounds on adipogenic differentiation and sought to develop more potent anti-adipogenic compound. We found that mansonone G (MG) suppressed adipocyte differentiation of 3T3-L1 cells, with a 40% decrease in lipid accumulation at 10 µM. MG derivatives including ether and ester analogues were then synthesized and assayed for their ability to suppress adipogenesis. A novel MG derivative, chlorobenzoyl MG (CBMG) most potently suppressed adipocyte differentiation with the decreased level of aP2 and adiponectin. Interestingly, CBMG treatment decreased the expression of CCAAT enhancer binding protein-α (C/EBPα) and peroxisome proliferator-activated receptor-γ (PPARγ). Further analysis confirmed that CBMG suppressed both the expression and activity of PPARγ, a master regulator of adipogenesis, and subsequently led to decreases in transcription of C/EBPα, aP2, and adiponectin in adipogenesis, thereby attenuating adipocyte differentiation. Our results suggest that a novel MG derivative, CBMG may have beneficial applications in the control of obesity through the suppression of PPARγ-induced adipocyte differentiation and lipid accumulation.

Transcriptional coactivator with PDZ-binding motif is required to sustain testicular function on aging.

Transcriptional coactivator with PDZ-binding motif (TAZ) directly interacts with transcription factors and regulates their transcriptional activity. Extensive functional studies have shown that TAZ plays critical regulatory roles in stem cell proliferation, differentiation, and survival and also modulates the development of organs such as the lung, kidney, heart, and bone. Despite the importance of TAZ in stem cell maintenance, TAZ function has not yet been evaluated in spermatogenic stem cells of the male reproductive system. Here, we investigated the expression and functions of TAZ in mouse testis. TAZ was expressed in spermatogenic stem cells; however, its deficiency caused significant structural abnormalities, including atrophied tubules, widened interstitial space, and abnormal Leydig cell expansion, thereby resulting in lowered sperm counts and impaired fertility. Furthermore, TAZ deficiency increased the level of apoptosis and senescence in spermatogenic cells and Leydig cells upon aging. The expression of senescence-associated ß-galactosidase (SA-ßgal), secretory phenotypes, and cyclin-dependent kinase inhibitors (p16, p19, and p21) significantly increased in the absence of TAZ. TAZ downregulation in testicular cells further increased SA-ßgal and p21 expression induced by oxidative stress, whereas TAZ overexpression decreased p21 induction and prevented senescence. Mechanistic studies showed that TAZ suppressed DNA-binding activity of p53 through a direct interaction and thus attenuated p53-induced p21 gene transcription. Our results suggested that TAZ may suppress apoptosis and premature senescence in spermatogenic cells by inhibiting the p53-p21 signaling pathway, thus playing important roles in the maintenance and control of reproductive function.

Catechins activate muscle stem cells by Myf5 induction and stimulate muscle regeneration.

Muscle weakness is one of the most common symptoms in aged individuals and increases risk of mortality. Thus, maintenance of muscle mass is important for inhibiting aging. In this study, we investigated the effect of catechins, polyphenol compounds in green tea, on muscle regeneration. We found that (-)-epicatechin gallate (ECG) and (-)-epigallocatechin-3-gallate (EGCG) activate satellite cells by induction of Myf5 transcription factors. For satellite cell activation, Akt kinase was significantly induced after ECG treatment and ECG-induced satellite cell activation was blocked in the presence of Akt inhibitor. ECG also promotes myogenic differentiation through the induction of myogenic markers, including Myogenin and Muscle creatine kinase (MCK), in satellite and C2C12 myoblast cells. Finally, EGCG administration to mice significantly increased muscle fiber size for regeneration. Taken together, the results suggest that catechins stimulate muscle stem cell activation and differentiation for muscle regeneration.

Anti-inflammatory activity of chloroquine and amodiaquine through p21-mediated suppression of T cell proliferation and Th1 cell differentiation.

Chloroquine (CQ) and amodiaquine (AQ) have been used for treating or preventing malaria for decades, and their application has expanded into treating inflammatory disease in humans. CQ and AQ are applicable for controlling rheumatoid arthritis, but their molecular mechanisms of anti-inflammatory activity remain to be elucidated. In this study, we examined the effects of CQ and AQ on T cell activation and T cell-mediated immune response. CQ had no significant effect on T cell numbers, but decreased the population of T cells with a high division rate. However, AQ treatment significantly increased the number of cells with low division rates and eliminated cells with high division rates, resulting in the inhibition of T cell proliferation triggered by T cell receptor stimulation, of which inhibition occurred in developing effector T helper and regulatory T cells, regardless of the different exogenous cytokines. Interestingly, the cyclin-dependent kinase inhibitor p21 was significantly and dose-dependently increased by CQ, and more potently by AQ, while other cell cycle regulators were unchanged. Both CQ and AQ elevated the transcription level of p21 though the activation of p53, but also blocked p21 protein degradation in the presence of cycloheximide, causing p21 protein accumulation mainly in the nucleus. Sustained treatment of developing T cells with either CQ or AQ suppressed IFN-γ production in a dose dependent manner and potently inhibited the differentiation of IFN-γ-producing Th1 cells. These results demonstrate that CQ and AQ increase the expression level of p21 and inhibit T cell proliferation and the development of IFN-γ-producing Th1 cells, thereby revealing beneficial roles in treating a wide range of chronic inflammatory diseases mediated by inflammatory T cells.

Suppression of Inflammatory cytokine production by ar-Turmerone isolated from Curcuma phaeocaulis.

Rhizomes of Curcuma phaeocaulis Valeton (Zingiberaceae) have traditionally been used for controlling inflammatory conditions. Numerous studies have aimed to isolate and characterize the bioactive constituents of C. phaeocaulis. It has been reported that its anti-inflammatory properties are a result of cyclooxygenase-2 inhibition; however, its effect on the T-cell function remains to be elucidated. In this study, four known sesquiterpenoids, viz., ar-turmerone (TM), germacrone (GM), (+)-(4S,5S)-germacrone-4,5-epoxide (GE), and curzerenone (CZ), were isolated from C. phaeocaulis rhizomes and evaluated for their effects on the CD4(+) T-cell function. While GM, GE, and CZ had no effect on the activation of splenic T cells or CD4(+) T cells, TM suppressed the interferon (IFN)-γ production, without affecting the interleukin (IL)-4 expression. TM also decreased the expression of IL-2 in CD4(+) T cells, but did not change their cell-division rates upon stimulation. These results suggest that TM, a major constituent of C. phaeocaulis rhizomes selectively exerts potent anti-inflammatory effects via suppression of the inflammatory cytokines IFN-γ and IL-2.

Anti-adipogenic activity of the naturally occurring phenanthroindolizidine alkaloid antofine via direct suppression of PPARγ expression.

Antofine (ANTF) is a phenanthroindolizidine alkaloid isolated from the root of Cynanchum paniculatum Kitagawa (Asclepiadaceae), which is used as an herbal remedy for pain and inflammation. ANTF also possesses antiviral and antitumorigenic activities. In this study, we investigated the role of ANTF in adipogenesis. Chronic ABTF administration suppressed adipocyte differentiation and marker expression in a dose-dependent manner. Furthermore, acute administration of ANTF at early stages of differentiation process inhibited lipid droplet formation and adipogenic gene expression. ANTF Treatment decreased expression of PPARγ protein, a master transcription factor in the regulation of adipocyte differentiation, leading to a suppression of aP2 promoter activity. These results suggest that ANTF exerts potent anti-adipogenic effects via direct suppression of PPARγ protein expression, with consequent downregulation of adipogenic gene expression.

A FoxO1-dependent, but NRF2-independent induction of heme oxygenase-1 during muscle atrophy.

Skeletal muscle plays key roles in metabolic homeostasis. Loss of muscle mass, called muscle atrophy exacerbates disease-associated metabolic perturbations. In this study, we characterized the molecular functions and mechanisms underlying regulation of skeletal muscle atrophy induced by denervation. Denervation significantly increased the expression of heme oxygenase-1 (HO-1) and atrogenes in skeletal muscle. Forkhead box protein O1 (FoxO1) drastically increased in atrophied muscle and selectively stimulated HO-1 gene transcription through direct DNA binding. Lack of HO-1 substantially attenuated muscle atrophy, whereas HO-1 overexpression caused muscle damage in vitro and in vivo. Collectively, HO-1 induced by FoxO1 may cause skeletal muscle atrophy.

Functional evaluation of GJB2 variants in nonsyndromic hearing loss.

Mutations in the gap junction ß2 (GJB2) gene, encoding the connexin26 (CX26) protein, are the most common cause of non-syndromic hearing loss (HL) in many populations. In the East Asian population, two variants, p.V27I (c.79G>A) and p.E114G (c.341G>A), are considered benign polymorphisms since these variants have been identified in both HL patients and normal hearing controls. However, some studies have postulated that homozygotes carrying both p.V27I and p.E114G variants could cause HL. To elucidate possible roles of these variants, we used in vitro approaches to directly assess the pathogenicity of four haplotypes generated by the two polymorphisms: VE (wild type), I*E (p.V27I variant only), VG* (p.E114G variant only), I*G* (both variants). In biochemical coupling assays, the gap junctions (GJs) composed of VG* and I*G* types displayed defective channel activities compared with those of VE wild types or I*E types, which showed normal channel activities. Interestingly, the defect in hemichannel activity was a bit less severe in I*G* type than VG* type, suggesting that I* variant (p.V27I) may compensate for the deleterious effect of G* variant (p.E114G) in hemichannel activities. Our population studies using 412 Korean individuals showed that I*G* type was detected at around 20% in both HL patients and normal controls, suggesting that I*G* type may not be a pathogenic polymorphism. In contrast, VG* type was very rare (3/824) and detected only in HL patients, suggesting that VG* homozygotes (VG*/VG*) or compound heterozygotes carrying VG* type with other mutations may cause HL.