[Show abstract][Hide abstract] ABSTRACT: Mesenchymal stem cell (MSC) differentiation is regulated by the extracellular matrix (ECM) through activation of intracellular signaling mediators. The stiffness of the ECM was shown to be an important regulatory factor for MSC differentiation, and transcriptional coactivator with PDZ-binding motif (TAZ) was identified as an effector protein for MSC differentiation. However, the detailed underlying mechanism regarding the role of ECM stiffness and TAZ in MSC differentiation is not yet fully understood. In this report, we showed that ECM stiffness regulates MSC fate through ERK or JNK activation. Specifically, a stiff hydrogel matrix stimulates osteogenic differentiation concomitant with increased nuclear localization of TAZ, but inhibits adipogenic differentiation. ERK and JNK activity was significantly increased in cells cultured on a stiff hydrogel. TAZ activation was induced by ERK or JNK activation on a stiff hydrogel because exposure to an ERK or JNK inhibitor significantly decreased the nuclear localization of TAZ, indicating that ECM stiffness-induced ERK or JNK activation is important for TAZ-driven osteogenic differentiation. Taken together, these results suggest that ECM stiffness regulates MSC differentiation through ERK or JNK activation.
PLoS ONE 08/2015; 10(8):e0135519. DOI:10.1371/journal.pone.0135519 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transcriptional co-activator with PDZ binding motif (TAZ) plays a key role in the control of mesenchymal stem cell differentiation through its nuclear localization and subsequent interaction with master transcription factors. In particular, TAZ directly associates with MyoD and activates MyoD-induced myogenic gene expression, thereby enhancing myogenic differentiation. In this study, we aimed to isolate and characterize small molecules that could modulate myogenic differentiation via induction of TAZ nuclear localization.
GFP-TAZ stable cells were used in a high content imaging screen for specific small molecules that enhance nuclear localization of TAZ. We then studied the effects of such TAZ modulators on myocyte differentiation of C2C12 cells and myogenic transdifferentiation of MEF cells in vitro and muscle regeneration in vivo.
This approach led to identification of a TAZ modulator, TM-53, and its structural isomer TM-54; each compound strongly enhanced nuclear localization of TAZ by reducing S89-phosphorylation and dose-dependently augmented myogenic differentiation and MyoD-mediated myogenic transdifferentiation through an activation of MyoD-TAZ interaction. The myogenic stimulatory effects of TM-53 and TM-54 were impaired in the absence of TAZ, but retrieved by the restoration of TAZ. In addition, administration of TM-53 and TM-54 enhanced injury-induced muscle regeneration in vivo and attenuated myofiber injury in vitro.
Novel TAZ modulators TM-53 and TM-54 accelerate myogenic differentiation and improve muscle regeneration and function after injury, implicating that small molecules targeting the nuclear localization of TAZ have beneficial roles in skeletal muscle regeneration and recovery of muscle degenerative diseases.
British Journal of Pharmacology 05/2014; 171(17). DOI:10.1111/bph.12755 · 4.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Shear stress activates cellular signaling involved in cellular proliferation, differentiation, and migration. However, the mechanisms of mesenchymal stem cell (MSC) differentiation under interstitial flow are not fully understood. Here, we show the increased osteogenic differentiation of MSCs under exposure to constant, extremely low shear stress created by osmotic pressure-induced flow in a microfluidic chip. The interstitial level of shear stress in the proposed microfluidic system stimulated nuclear localization of TAZ (transcriptional coactivator with PDZ-binding motif), a transcriptional modulator of MSCs, activated TAZ target genes such as CTGF and Cyr61, and induced osteogenic differentiation. TAZ-depleted cells showed defects in shear stress-induced osteogenic differentiation. In shear stress induced cellular signaling, Rho signaling pathway was important forthe nuclear localization of TAZ. Taken together, these results suggest that TAZ is an important mediator of interstitial flow-driven shear stress signaling in osteoblast differentiation of MSCs.
PLoS ONE 03/2014; 9(3):e92427. DOI:10.1371/journal.pone.0092427 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Osteoporosis is a degenerative bone disease characterized by low bone mass, and is caused by an imbalance between osteoblastic bone formation and osteoclastic bone resorption. It is known that the bioactive compounds present in green tea increase osteogenic activity and decrease the risk of fracture by improving bone mineral density. However, the detailed mechanism underlying these beneficial effects has yet to be elucidated. In this study, we investigated the osteogenic effect of (-)-epicatechin gallate (ECG), a major bioactive compound found in green tea. We found that ECG effectively stimulates osteoblast differentiation, indicated by the increased expression of osteoblastic marker genes. Upregulation of osteoblast marker genes is mediated by increased expression and interaction of the transcriptional coactivator with PDZ-binding motif (TAZ) and runt-related transcription factor 2 (Runx2). ECG facilitates nuclear localization of TAZ through PP1A. PP1A is essential for osteoblast differentiation since inhibition of PP1A activity was shown to suppress ECG-mediated osteogenic differentiation. Taken together, the results showed that ECG stimulates osteoblast differentiation through the activation of TAZ and Runx2, revealing a novel mechanism for green tea-stimulated osteoblast differentiation.
[Show abstract][Hide abstract] ABSTRACT: TAZ (transcriptional coactivator with PDZ-binding motif) is a transcriptional modulator that regulates mesenchymal stem cell differentiation. It stimulates osteogenic differentiation while inhibiting adipocyte differentiation. FGFs (fibroblast growth factors) stimulate several signaling proteins to regulate their target genes, which are involved in cell proliferation, differentiation, and cell survival. Within this family, FGF2 stimulates osteoblast differentiation though a mechanism that is largely unknown. In this report, we show that TAZ mediates FGF2 signaling in osteogenesis. We observed that FGF2 increases TAZ expression by stimulating its mRNA expression. Depletion of TAZ using small hairpin RNA blocked FGF2-mediated osteogenic differentiation. FGF2 induced TAZ expression was stimulated by ERK (extracellular signal-regulated kinase) activation and the inhibition of ERK blocked TAZ expression. FGF2 increased nuclear localization of TAZ and, thus, facilitated the interaction of TAZ and Runx2, activating Runx2-mediated gene transcription. Taken together, these results suggest that TAZ is an important mediator of FGF2 signaling in osteoblast differentiation.
Bone 10/2013; 58. DOI:10.1016/j.bone.2013.09.024 · 3.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Obesity causes several metabolic diseases, including diabetes. Adipogenic differentiation is an important event for fat formation in obesity. Natural compounds that inhibit adipogenic differentiation are frequently screened to develop therapeutic drugs for treating obesity. Here we investigated the effects of phorbaketal A, a natural marine compound, on adipogenic differentiation of mesenchymal stem cells. Phorbaketal A significantly inhibited adipogenic differentiation as indicated by less fat droplets and decreased expression of adipogenic marker genes. The expression of TAZ (transcriptional coactivator with PDZ-binding motif), an inhibitor of adipogenic differentiation, significantly increased during adipogenic differentiation in the presence of phorbaketal A. Phorbaketal A increased the interaction of TAZ and PPARγ to suppress PPARγ (peroxisome proliferator-activated receptor γ) target gene expression. TAZ-depleted cells showed higher adipogenic potential than that of control cells even in the presence of phorbaketal A. During cellular signaling induced by phorbaketal A, ERK (extracellular signal-regulated kinase) played an important role in adipogenic suppression; an inhibitor of ERK blocked phorbaketal A-induced adipogenic suppression. Thus, the results show that phorbaketal A inhibits adipocyte differentiation through TAZ.
European journal of pharmacology 09/2013; 718(1-3). DOI:10.1016/j.ejphar.2013.08.035 · 2.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Hippo signaling pathway regulates organ size, tissue regeneration, and stem cell self-renewal. The two key downstream transcription coactivators in this pathway, Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), mediate the major gene regulation and biological functions of the Hippo pathway. The biological functions of YAP and TAZ in many tissues are known; however, their roles in skin wound healing remain unclear. To analyze whether YAP and/or TAZ are required for cutaneous wound healing, we performed small interfering RNA (siRNA)-mediated knockdown of YAP/TAZ in full-thickness skin wounds. YAP is strongly expressed in the nucleus and cytoplasm in the epidermis and hair follicle. Interestingly, YAP is expressed in the nucleus in the dermis at 2 and 7 days after wounding. TAZ normally localizes to the cytoplasm in the dermis but is distributed in both the nucleus and cytoplasm at 1 day after wounding. The knockdown of YAP and TAZ markedly delayed the rate of wound closure and reduced the transforming growth factor-β1 (TGF-β1) expression in the wound. YAP and TAZ also modulate the expression of TGF-β1 signaling pathway components such as Smad-2, p21, and Smad-7. These results suggest that YAP and TAZ localization to the nucleus is required for skin wound healing.Journal of Investigative Dermatology advance online publication, 10 October 2013; doi:10.1038/jid.2013.339.
[Show abstract][Hide abstract] ABSTRACT: A T-box-containing protein expressed in T cells (T-bet) is a key transcription factor involved in the regulation of Th cell differentiation. Although T-bet-deficient CD4(+) T cells fail to produce IFN-γ and typically differentiate into Th2 cells in vitro, ectopic overexpression of T-bet elevates IFN-γ and suppresses production of IL-2 and Th2 cytokines through different mechanisms. Despite the importance of the T-bet protein level, the regulatory mechanisms that control T-bet protein stability are largely unknown. In this study, we found that T-bet underwent proteasomal degradation via ubiquitination at Lys-313. Despite its robust accumulation following lysine mutation, T-bet(K313R) failed to increase IFN-γ production because of diminished DNA binding activity, as demonstrated in the crystal structure of T-bet-DNA complex. Strikingly, T-bet(K313R) entirely lost the ability to suppress IL-2 production and Th2 cell development; this was due to loss of its interaction with NFAT1. We further identified that the T-bet(K313R) reduced the phosphorylation of T-bet at Thr-302, and that threonine phosphorylation was essential for T-bet interaction with NFAT1 and suppression of NFAT1 activity. Retroviral transduction of T-bet(T302A) into T-bet-deficient cells restored IFN-γ levels compared with those induced by wild-type T-bet, but this mutant failed to inhibit IL-2 and Th2 cytokine production. Collectively, these data show that Lys-313 in the T-box domain is essential for controlling T-bet protein stability via ubiquitin-dependent degradation, T-bet binding to the IFN-γ promoter, and for the interaction with and suppression of NFAT1. Thus, multiple posttranslational modifications of T-bet are involved in fine-tuning cytokine production during Th cell development.
The Journal of Immunology 04/2013; 190(11). DOI:10.4049/jimmunol.1203403 · 4.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transcriptional coactivator with PDZ-binding motif (TAZ) physically interacts with a variety of transcription factors and
modulates their activities involved in cell proliferation and mesenchymal stem cell differentiation. TAZ is highly expressed
in the kidney, and a deficiency of this protein results in multiple renal cysts and urinary concentration defects; however,
the molecular functions of TAZ in renal cells remain largely unknown. In this study, we examined the effects of osmotic stress
on TAZ expression and activity in renal cells. We found that hyperosmotic stress selectively increased protein phosphorylation
at tyrosine 316 of TAZ and that this was enhanced by c-Abl activation in response to hyperosmotic stress. Interestingly, phosphorylated
TAZ physically interacted with nuclear factor of activated T cells 5 (NFAT5), a major osmoregulatory transcription factor,
and subsequently suppressed DNA binding and transcriptional activity of NFAT5. Furthermore, TAZ deficiency elicited an increase
in NFAT5 activity in vitro and in vivo, which then reverted to basal levels following restoration of wild-type TAZ but not mutant TAZ (Y316F). Collectively, the
data suggest that TAZ modulates cellular responses to hyperosmotic stress through fine-tuning of NFAT5 activity via tyrosine
[Show abstract][Hide abstract] ABSTRACT: Osteoporosis arises from an imbalance between osteoblastic bone formation and osteoclastic bone resorption. In this study, we screened molecules from marine natural products that stimulate osteoblast differentiation. We found that phorbaketal A significantly stimulates osteoblast differentiation in mesenchymal cells. Increased interaction of TAZ and Runx2 stimulated phorbaketal A-induced expression of osteoblastic marker genes. The activation of ERK was important for the stimulation of differentiation because an inhibitor of ERK blocked phorbaketal A-induced osteogenic differentiation. Taken together, the results showed that phorbaketal A stimulates TAZ-mediated osteoblast differentiation through the activation of ERK.
[Show abstract][Hide abstract] ABSTRACT: Obesity is a major health problem worldwide and can increase the risk for several chronic diseases, including diabetes and cardiovascular disease. In this study, we screened small compounds isolated from natural products for the development of an anti-obesity drug. Among them, idesolide, a spiro compound isolated from the fruits of Idesia polycarpa Maxim, showed a significant suppression of the adipogenic differentiation in mesenchymal cells, as indicated by the decrease in fat droplets and expression of adipogenic marker genes such as aP2 and adiponectin. Idesolide inhibits the PPARγ-mediated gene transcription in a dose-dependent manner, revealed by luciferase reporter gene assay. During adipogenic differentiation, idesolide inhibits nitric oxide production through the suppression of iNOS expression, and the increased adipogenic differentiation by arginine, the substrate for NOS, is significantly inhibited by idesolide, suggesting that the inhibition of nitric oxide production plays a major role in idesolide-induced adipogenic suppression. Taken together, the results reveal that idesolide has anti-adipogenic activity and highlight its potential in the prevention and treatment of obesity.
European journal of pharmacology 04/2012; 685(1-3):218-23. DOI:10.1016/j.ejphar.2012.04.018 · 2.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Kaempferol (KMP) exerts protective effects against both osteoporosis and obesity by regulating cellular activities, but the underlying molecular mechanisms have not been fully elucidated. TAZ (transcriptional coactivator with PDZ-binding motif) modulates both osteoblast and adipocyte differentiation from mesenchymal stem cells by stimulating the activities of RUNX2 (runt-related transcription factor 2) and suppressing the activities of PPARγ (peroxisome proliferator-activated receptor γ). In this study, we investigated the effects of KMP on TAZ regulated osteoblast and adipocyte differentiation. KMP increased the osteoblast differentiation of mesenchymal cells by facilitating the physical interaction between TAZ and RUNX2, thus the increasing transcriptional activities of RUNX2. KMP also enhanced the association of TAZ with PPARγ, thereby suppressing the gene transcription of PPARγ targets and resulting in diminished adipocyte differentiation. Interestingly, the regulatory effects of kaempferol on RUNX2 and PPARγ-mediated transcriptional activity were impaired in TAZ-null mouse embryonic fibroblasts but recovered by restoration of TAZ expression. Our results demonstrate that KMP fortifies TAZ activity, which enhances RUNX2-mediated osteoblast differentiation and suppresses PPARγ-stimulated adipocyte differentiation, indicating the potential of KMP as an effective therapeutic reagent for controlling bone loss and adiposity through TAZ activation.
Bone 11/2011; 50(1):364-72. DOI:10.1016/j.bone.2011.10.035 · 3.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Emerging evidence indicates that NADPH oxidase (NOX) and its reactive oxygen species (ROS) products modulate a variety of cellular events, including proliferation, differentiation, and apoptosis. In this study, we investigated the functions of NOX2 and ROS in immune modulation using NOX2 knockout (KO) mice. Interestingly, NOX2 KO mice spontaneously developed arthritis with onset at 6-7 wk of age and high incidence (60%) at 15-18 wk of age. Arthritis severity in NOX2 KO mice was proportionally increased with age and higher in females than in males. Bone destruction was confirmed by microcomputed tomography scanning and histological analyses of joints. Inflammatory factors, including TNF-α, IL-1β, and RANKL, and serum level of anti-type II collagen IgG were significantly increased in NOX2 KO mice. In addition, NOX2 deficiency perturbed the immune system upon aging. NOX2 KO mice demonstrated preferred development of CD11b+Gr-1+ myeloid cells with profound production of proinflammatory cytokines and augmented expression of IL-17 through the activation of STAT3 and RORγt in vivo. NOX2 deficiency increased differentiation of effector Th cells in vitro and decreased CD25+FoxP3+ Treg cells both in vitro and in vivo. Furthermore, adoptive transfer of NOX2-deficient CD4(+) T cells into RAG KO mice increased arthritic inflammation compared with WT cells. These results demonstrated that NOX2 deficiency affected the development of CD11b+ myeloid cells and Th17/Treg cells, and thus promoted inflammatory cytokine production and inflammatory arthritis development, strongly supporting a crucial role for ROS generation in the modulation of Th17/Treg cell development and its related inflammatory immune response upon aging.
Proceedings of the National Academy of Sciences 06/2011; 108(23):9548-53. DOI:10.1073/pnas.1012645108 · 9.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The bioflavonoid, hesperedin, promotes osteoblast differentiation in human mesenchymal stem cells, indicating an anabolic effect of hesperedin on bone metabolism. Murine bone marrow mesenchymal stem cells undergo myogenic differentiation as well as osteogenic differentiation. We therefore explored whether hesperedin modulates muscle cell differentiation.
Myoblast C2C12 cells were differentiated into muscle cells in the presence or absence of hesperedin. The effects of hesperedin on myogenic differentiation were determined by analysing specific muscle markers in vitro using reporter gene assays, immunoblotting, RT-PCR and DNA pull-down assays. In vivo, the effects of hesperedin were assessed using the freeze injury-induced muscle regeneration model in mice and daily injections of hesperedin for 6 days.
Hesperedin promoted myogenic differentiation, in a dose-dependent manner, by increasing myogenin gene expression. MyoD-induced myogenin gene transcription was enhanced by hesperedin, as this bioflavonoid augmented the nuclear localization and myogenin promoter-binding of MyoD. In addition, hesperedin increased myogenin and muscle creatine kinase gene expression during myogenic differentiation from C3H10T1/2 mesenchymal stem cells in a MyoD-dependent manner and accelerated in vivo muscle regeneration induced by muscle injury.
Our results demonstrate that hesperedin promoted myogenic differentiation in vitro and in vivo through activation of MyoD-mediated myogenin expression, suggesting a beneficial role in promoting muscle regeneration, following injury.
British Journal of Pharmacology 06/2011; 163(3):598-608. DOI:10.1111/j.1476-5381.2011.01243.x · 4.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Two new sesterterpenoids, phorbasones A (1) and B (2), were isolated from the Korean marine sponge Phorbas sp. Their complete structures were elucidated by spectral data and chemical reactions. Phorbasone A exhibited a positive effect on the calcium deposition activity in C3H10T1/2 cells. The biogenic origin of the core structure is believed to be through a novel rearrangement from the ansellone carbon structure.
[Show abstract][Hide abstract] ABSTRACT: T-box-containing protein expressed in T cells (T-bet) is a master transcription factor for the development of interferon (IFN) gamma-producing T helper 1 (Th1) cells and also functions in other immune cells including natural killer (NK), cytotoxic T lymphocytes and dendritic cells. T-bet-deficient mice increased susceptibility to viral infection and tumor development due to the defective functions of immune cells. T-bet is known to play a key role in NK-mediated antimetastatic response; however, it remains to be characterized whether T-bet is essential for in vivo tumor suppression mediated by T cells. Here, we have investigated in vivo tumor suppression effect of T-bet-restored T cells using T cell-specific and inducible T-bet transgenic mice generated in a T-bet-deficient background. T-bet-null mice increased susceptibility to tumor development, whereas induction of T cell-specific T-bet expression upon melanoma cell injection substantially suppressed tumor development by inducing IFNgamma production in T cells and tumor cell apoptosis. Late induction of T-bet expression in tumor-bearing mice produced comparable amounts of IFNgamma with control and significantly decreased tumor volume. In addition, increased melanoma lung metastasis in T-bet-deficient mice was strikingly inhibited by T-bet restoration in T cells. Intravenous injection of activated Th1 cells, not T-bet-null Th1 cells, attenuated metastatic melanoma progression, in addition, restoration of T-bet in T-bet-null Th1 cells certainly retrieved antimetastatic activity. These results suggest that T-bet expression in T cells is crucial for the control of tumor development and antimetastatic activity.
International Journal of Cancer 11/2010; 127(9):2129-37. DOI:10.1002/ijc.25238 · 5.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pinusolide and its derivative, 15-methoxypinusolidic acid (15-MPA) are diterpenoid compounds isolated from Biota orientalis, which has been used as a Korean folk medicine for treating inflammatory disorders. Pinusolide and 15-MPA suppress nitric oxide generation by suppressing inducible nitric oxide synthase and exerted anti-inflammatory functions, whereas other functions and regulatory mechanisms are largely unknown. In this study, we investigated whether pinusolide and 15-MPA modulate adipocyte differentiation from pre-adipocytes 3T3-L1 cells. We found that 15-MPA, not pinusolide, suppressed adipocyte differentiation in a dose-dependent manner, as revealed by lipid droplet formation and expression of adipogenic genes such as adiponectin and aP2. 15-MPA did not affect mRNA and protein levels of PPARgamma, a key adipogenic transcription factor, whereas transcriptional activity of PPARgamma was significantly attenuated by 15-MPA. While aP2 promoter activity was increased by ectopic overexpression of PPARgamma or by rosiglitazone-induced endogenous PPARgamma activation, PPARgamma-induced aP2 promoter activity was inhibited in the presence of 15-MPA. These results suggest that 15-MPA suppresses adipocyte differentiation through the inhibition of PPARgamma-dependent adipogenic gene expression.
Archives of Pharmacal Research 07/2010; 33(7):1035-41. DOI:10.1007/s12272-010-0709-0 · 2.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Myoblast differentiation is indispensable for skeletal muscle formation and is governed by the precisely coordinated regulation of a series of transcription factors, including MyoD and myogenin, and transcriptional coregulators. TAZ (transcriptional coactivator with PDZ-binding motif) has been characterized as a modulator of mesenchymal stem cell differentiation into osteoblasts and adipocytes through its regulation of lineage-specific master transcription factors. In this study, we investigated whether TAZ affects myoblast differentiation, which is one of the differentiated lineages of mesenchymal stem cells. Ectopic overexpression of TAZ in myoblasts increases myogenic gene expression in a MyoD-dependent manner and hastens myofiber formation, whereas TAZ knockdown delays myogenic differentiation. In addition, enforced coexpression of TAZ and MyoD in fibroblasts accelerates MyoD-induced myogenic differentiation. TAZ physically interacts with MyoD through the WW domain and activates MyoD-dependent gene transcription. TAZ additionally enhances the interaction of MyoD with the myogenin gene promoter. These results strongly suggest that TAZ functions as a novel transcriptional modulator of myogenic differentiation by promoting MyoD-mediated myogenic gene expression.
The FASEB Journal 05/2010; 24(9):3310-20. DOI:10.1096/fj.09-151324 · 5.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The ligand-activated transcription factor, peroxisome proliferator-activated receptor (PPAR)gamma, and its ligands inhibit pro-inflammatory cytokine production by immune cells, thus exerting anti-inflammatory activity. As a non-thiazolidinedione PPARgamma ligand, KR62980 has anti-diabetic and anti-adipogenic activities, but its anti-inflammatory function has yet to be characterized. In this study, we investigated the functions and mechanisms of KR62980 in the activation and differentiation of CD4+ T helper (Th) cells by comparing its effects with those of a thiazolidinedione PPARgamma ligand, rosiglitazone. KR62980 dose-dependently and significantly suppressed TCR-triggered Th cell proliferation by suppressing IL-2/IL-2Ralpha-mediated signaling. Both KR62980 and rosiglitazone suppressed IFNgamma production in a dose-dependent manner, whereas IL-4 gene expression was specifically suppressed by only KR62980. In addition, sustained KR62980 treatment diminished Th2 cytokine production by inhibiting c-Maf expression. In vivo administration of KR62980 in a model of allergic asthma significantly attenuated eotaxin-induced eosinophil infiltration, allergic cytokine production and collagen deposition in the lung. KR62980 also decreased goblet cell hyperplasia in the airway and mucous cell metaplasia in nasal epithelium, concurrent with decreases of allergic Th2 cytokines and IL-17 in the draining lymph node. In conclusion, a novel PPARgamma ligand, KR62980, suppresses in vitro Th2 cell differentiation and attenuates in vivo OVA-induced airway inflammation, suggesting a beneficial role for KR62980 in the treatment of allergic asthma and allergic rhinitis.
[Show abstract][Hide abstract] ABSTRACT: Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-activated transcription factor that plays a pivotal role in the modulation of gene expression involved in adipocyte differentiation and insulin sensitivity. It has been previously established that thiazolidinedione (TZD) PPARgamma ligands such as rosiglitazone have potent anti-diabetic and adipogenic activities. A novel non-TZD ligand for PPARgamma, KR62980 has recently been characterized to increase insulin sensitivity and to be weakly adipogenic in 3T3-L1 cells or anti-adipogenic in rosiglitazone-induced adipocyte differentiation. In this study, we have confirmed that KR62980 substantially suppresses rosiglitazone-induced adipocyte differentiation and attenuates adipogenic gene expression via an induced reduction in PPARgamma activity. KR62980 increased the nuclear localization of TAZ, a PPARgamma suppressor, and also enhanced the interaction between PPARgamma and TAZ, thus resulting in the TAZ-mediated suppression of PPARgamma activity. Furthermore, KR62980 failed to suppress PPARgamma-mediated adipogenic gene expression and adipocyte differentiation in TAZ knockdown 3T3-L1 cells, thus indicating a TAZ-dependent suppressive activity of KR62980 on PPARgamma-mediated function. These findings strongly suggest that the novel PPARgamma ligand, KR62980, may prove to be beneficial to anti-adipogenic function through the suppression of PPARgamma-mediated adipocyte differentiation by activating TAZ.