研究者詳細 - 多胡　めぐみ

論文 - 多胡　めぐみ

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The critical role of the phosphorylation of STAT3 at Y705 in ALCL-associated NPM-ALK-induced transforming activity

Lin X., Korai A., Nakazawa Y., Tago K., Funakoshi-Tago M.

Cellular Signalling 136 2025年12月

ISSN 08986568

The fusion protein nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) drives oncogenesis in anaplastic large cell lymphoma (ALCL) by activating signal transducer and activator of transcription 3 (STAT3). NPM-ALK requires its kinase activity to induce STAT3 phosphorylation at tyrosine 705 (Y705) and promotes serine 727 (S727) phosphorylation via JNK activation. However, the role of these modifications in NPM-ALK-driven cellular transformation remains unclear. We herein utilized murine Ba/F3 cells expressing NPM-ALK to investigate the impact of these modifications. STAT3 knockdown, followed by reconstitution with wild-type STAT3 or its mutants (Y705F and S727A) revealed that Y705 phosphorylation was essential for NPM-ALK-mediated transformation. STAT3 knockdown suppressed the expression of NPM-ALK-induced STAT3 target genes (c-Myc, Pim, IL-6, and SOCS3) as well as cell proliferation, tumor formation, and spleen, liver, and lymph node enlargement. These effects were restored upon reconstitution with wild-type STAT3 or the S727A mutant, but not the Y705F mutant, confirming the essential role of Y705 phosphorylation in these biological processes. Additionally, wild-type and mutant STAT3 proteins exhibited differential stability, with Y705F being less stable and S727A being more stable. Lysosomal inhibition by bafilomycin A1 increased the expression of wild-type STAT3 and the Y705F mutant, but had no effect on the S727A mutant. Cycloheximide chase assays further confirmed that S727 phosphorylation regulated STAT3 degradation via the lysosomal pathway. These results identify a novel NPM-ALK-induced oncogenic mechanism mediated by STAT3 phosphorylation, highlighting potential therapeutic targets for ALCL.

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TRPV1 attenuates epithelial-mesenchymal transition via calpain-protein tyrosine phosphatase pathway in lens epithelial cells

Nakazawa Y., Nishizawa F., Kawata S., Sugiyama Y., Nagai N., Yamamoto N., Funakoshi-Tago M.

Experimental Eye Research 258 2025年09月

ISSN 00144835

TRPV1, which is widely expressed throughout the body, is a non-selective cation channel activated by capsaicin. We previously reported that TRPV1 activation suppressed TGFβ2-induced epithelial-mesenchymal transition (EMT) by inhibiting Epidermal Growth Factor Receptor (EGFR) phosphorylation in lens epithelial cells (Sugiyama et al., 2021). However, the detailed molecular mechanism remains unclear. In this study, we focused on the calpain–protein tyrosine phosphatase (PTP) pathway to elucidate the detailed mechanism underlying TRPV1-induced EMT suppression. Calpain and PTP inhibitors mitigated the suppressive effect of capsaicin on TGFβ2-induced EMT in vitro and ex vivo. Finally, we shown that CalpainS1 and PTPN9 overexpression abrogated the effect of capsaicin on EMT in lens epithelial cells. Our findings indicate that calpain and PTP proteins are good candidates for preventing EMT after cataract surgery.

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Development of Keap1-Nrf2 Protein–Protein Interaction Inhibitor Activating Intracellular Nrf2 Based on the Naphthalene-2-acetamide Scaffold, and its Anti-Inflammatory Effects

Yasuda D., Toyoshima K., Kojima K., Ishida H., Kaitoh K., Imamura R., Kanamitsu K., Kojima H., Funakoshi-Tago M., Osawa M., Ohe T., Hirano T.

Chemmedchem 2025年

ISSN 18607179

Nuclear factor erythroid 2-related factor 2 (Nrf2) and Kelch-like ECH-associated protein 1 (Keap1) axis is an attractive therapeutic target for various intractable diseases. Although protein–protein interaction inhibitors against Keap1-Nrf2 have been developed over the past decade, more structural expansion is needed to improve efficacy. In this article, several candidate compounds are designed and synthesized as novel Nrf2 activators and their intracellular Nrf2-activating effects are evaluated. Among the synthesized compounds, a novel naphthalene-1,4-(4-ethoxybenzensulfonamide) bearing a tertiary acetamide side chain at the 2-position strongly activated intracellular Nrf2. Particularly, the pyrrolidine-type acetamide compound showed the strongest intracellular Nrf2 activation. X-ray cocrystallography revealed that this compound can bind to the DC domain of Keap1. Additionally, the pyrrolidine-type acetamide compound induced the mRNA expression of the representative Nrf2 target genes heme oxygenase-1 and NAD(P)H:quinone oxidoreductase 1. Moreover, the compound exhibited anti-inflammatory effects in a lipopolysaccharide-stimulated macrophage cell line. Conclusively, these results suggest that the pyrrolidine-type naphthalene-2-acetamide is a promising compound for the development of Nrf2 activators that can be applied to treat inflammatory diseases.

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High ambient temperature may induce presbyopia via TRPV1 activation

Nakazawa Y., Kuno Y., Shimada H., Nagai N., Hiramatsu N., Takeda S., Yamamoto N., Funakoshi-Tago M., Sasaki H.

Medical Molecular Morphology 57 （ 4 ） 268 - 276 2024年12月

ISSN 18601480

The prevalence of presbyopia and nuclear cataracts (NUC) is reported to be higher in tropical areas than that in other regions, suggesting a potential influence of high temperatures on lens health. Transient receptor potential vanilloid (TRPV) channels play a crucial role in detecting ambient temperatures across various species, with TRPV1 and TRPV4 expressed in lens epithelial cells. In this study, we investigated whether ambient temperatures affect TRPV1 and TRPV4 activity in the lens, potentially contributing to the development of presbyopia and NUC. We conducted experiments using cultured human lens epithelial cell lines under different temperature conditions. Our results revealed that the mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) and p38 pathways, downstream molecules of TRPV1, were activated, while Src family kinase, a downstream molecule of TRPV4, was inhibited at 37.5 °C culture compared to 35.0 °C. Confocal microscope images demonstrated higher expression of TRPV1 in 3D-structured cells under high-temperature culture conditions. Additionally, in organ culture lenses, higher elasticity was observed at elevated temperatures compared to that at lower temperatures. These results suggest that high ambient temperatures may induce lens sclerosis via TRPV1 activation, potentially contributing to the development of presbyopia and NUC.

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FL118 Is a Potent Therapeutic Agent against Chronic Myeloid Leukemia Resistant to BCR-ABL Inhibitors through Targeting RNA Helicase DDX5

Takeda K., Ohta S., Nagao M., Kobayashi E., Tago K., Funakoshi-Tago M.

International Journal of Molecular Sciences 25 （ 7 ） 2024年04月

ISSN 16616596

Chronic myeloid leukemia (CML) is induced by the expression of the fused tyrosine kinase BCR-ABL, which is caused by a chromosomal translocation. BCR-ABL inhibitors have been used to treat CML; however, the acquisition of resistance by CML cells during treatment is a serious issue. We herein demonstrated that BCR-ABL induced the expression of the RNA helicase DDX5 in K562 cells derived from CML patients in a manner that was dependent on its kinase activity, which resulted in cell proliferation and survival. The knockout of DDX5 decreased the expression of BIRC5 (survivin) and activated caspase 3, leading to apoptosis in K562 cells. Similar results were obtained in cells treated with FL118, an inhibitor of DDX5 and a derivative compound of camptothecin (CPT). Furthermore, FL118 potently induced apoptosis not only in Ba/F3 cells expressing BCR-ABL, but also in those expressing the BCR-ABL T315I mutant, which is resistant to BCR-ABL inhibitors. Collectively, these results revealed that DDX5 is a critical therapeutic target in CML and that FL118 is an effective candidate compound for the treatment of BCR-ABL inhibitor-resistant CML.

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The acetylation of STAT3 at K685 attenuates NPM-ALK-induced tumorigenesis

Korai A., Lin X., Tago K., Funakoshi-Tago M.

Cellular Signalling 114 2024年02月

ISSN 08986568

Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK), a fusion protein generated by a chromosomal translocation, is a causative gene product of anaplastic large cell lymphoma (ALCL). It induces cell proliferation and tumorigenesis by activating the transcription factor, signal transducer and activator of transcription factor 3 (STAT3). We herein demonstrated that STAT3 underwent acetylation at K685 in a manner that was dependent on the kinase activity of NPM-ALK. To investigate the role of STAT3 acetylation in NPM-ALK-induced oncogenesis, we generated Ba/F3 cells expressing NPM-ALK in which STAT3 was silenced by shRNA, named STAT3-KD cells, and then reconstituted wild-type STAT3 or the STAT3 K685R mutant into these cells. The phosphorylation level of the K685R mutant at Y705 and S727 was significantly higher than that of wild-type STAT3 in STAT3-KD cells. The expression of STAT3 target genes, such as IL-6, Pim1, Pim2, and Socs3, was more strongly induced by the reconstitution of the K685R mutant than wild-type STAT3. In addition, the proliferative ability of STAT3-KD cells reconstituted with the K685R mutant was slightly higher than that of STAT3-KD cells reconstituted with wild-type STAT3. In comparisons with the inoculation of STAT3-KD cells reconstituted with wild-type STAT3, the inoculation of STAT3-KD cells reconstituted with the K685R mutant significantly enhanced tumorigenesis and hepatosplenomegaly in nude mice. Collectively, these results revealed for the first time that the acetylation of STAT3 at K685 attenuated NPM-ALK-induced oncogenesis.

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Suppression of Neuroinflammation by Coffee Component Pyrocatechol via Inhibition of NF-κB in Microglia

Murata T., Tago K., Miyata K., Moriwaki Y., Misawa H., Kobata K., Nakazawa Y., Tamura H., Funakoshi-Tago M.

International Journal of Molecular Sciences 25 （ 1 ） 2024年01月

ISSN 16616596

According to numerous studies, it has been epidemiologically suggested that habitual coffee intake seems to prevent the onset of neurodegenerative diseases. In this study, we hypothesized that coffee consumption suppresses neuroinflammation, which is closely related to the development of neurodegenerative diseases. Using microglial BV-2 cells, we first found that the inflammatory responses induced by lipopolysaccharide (LPS) stimulation was diminished by both coffee and decaffeinated coffee through the inhibition of an inflammation-related transcription factor, nuclear factor-κB (NF-κB). Pyrocatechol, a component of roasted coffee produced by the thermal decomposition of chlorogenic acid, also exhibited anti-inflammatory activity by inhibiting the LPS-induced activation of NF-κB. Finally, in an inflammation model using mice injected with LPS into the cerebrum, we observed that intake of pyrocatechol as well as coffee decoctions drastically suppressed the accumulation of microglia and the expression of interleukin-6 (IL-6), tumor necrosis factor α (TNFα), CCL2, and CXCL1 in the inflammatory brain. These observations strongly encourage us to hypothesize that the anti-inflammatory activity of pyrocatechol as well as coffee decoction would be useful for the suppression of neurodegeneration and the prevention of the onsets of Alzheimer’s (AD) and Perkinson’s diseases (PD).

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Piezo1 channel causes lens sclerosis via transglutaminase 2 activation

Doki Y., Nakazawa Y., Sukegawa M., Petrova R.S., Ishida Y., Endo S., Nagai N., Yamamoto N., Funakoshi-Tago M., Donaldson P.J.

Experimental Eye Research 237 2023年12月

ISSN 00144835

Presbyopia is caused by age-related lenticular hardening, resulting in near vision loss, and it occurs in almost every individual aged ≥50 years. The lens experiences mechanical pressure during for focal adjustment to change its thickness. As lenticular stiffening results in incomplete thickness changes, near vision is reduced, which is known as presbyopia. Piezo1 is a mechanosensitive channel that constantly senses pressure changes during the regulation of visual acuity, and changes in Piezo1 channel activity may contribute to presbyopia. However, no studies have reported on Piezo1 activation or the onset of presbyopia. To elucidate the relevance of Piezo1 activation and cross-linking in the development of presbyopia, we analysed the function of Piezo1 in the lens. The addition of Yoda1, a Piezo1 activator, induced an increase in transglutaminase 2 (TGM2) mRNA expression and activity through the extra-cellular signal-regulated kinase (ERK) 1/2 and c-Jun-NH2-terminal kinase1/2 pathways. In ex vivo lenses, Yoda1 treatment induced γ-crystallin cross-linking via TMG2 activation. Furthermore, Yoda1 eye-drops in mice led to lenticular hardening via TGM2 induction and activation in vivo, suggesting that Yoda1-treated animals could serve as a model for presbyopia. Our findings indicate that this presbyopia-animal model could be useful for screening drugs for lens-stiffening inhibition.

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The citrus flavonoid, nobiletin inhibits neuronal inflammation by preventing the activation of NF-κB

Murata T., Ishiwa S., Lin X., Nakazawa Y., Tago K., Funakoshi-Tago M.

Neurochemistry International 171 2023年12月

ISSN 01970186

Nobiletin (5,6,7,8,3′,4′-hexamethoxyflavone) is one of the flavonoids found in shikuwasa, a popular citrus fruit in Okinawa, Japan. It exerts various pharmacological effects, such as anti-tumor, antioxidant, and anti-inflammatory activities. We herein investigated whether nobiletin attenuated lipopolysaccharide (LPS)-induced inflammatory responses in the murine microglial cell line BV-2 and neuroinflammation in mice induced by an intracerebral injection of LPS. In BV-2 cells, nobiletin significantly inhibited the LPS-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2) by preventing the mRNA expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), respectively. Nobiletin also inhibited the LPS-induced mRNA expression of CCL2, CXCL1, IL-6, and TNFα. Nobiletin markedly attenuated the transcriptional activity of the NF-κB p65 subunit without affecting the degradation of IκBα or the nuclear localization of the NF-κB p65 subunit. Nobiletin also inhibited the LPS-induced activation of JNK, but not ERK or p38, in BV-2 cells. Furthermore, the administration of nobiletin significantly suppressed the accumulation of microglia and induction of the mRNA expression of CCL2, CXCL1, IL-6, and TNFα in the murine brain induced by injecting LPS into the striatum. Collectively, these results suggest the potential of nobiletin as a candidate anti-inflammatory drug for the prevention of neuroinflammation.

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Aquaporins contribute to vacuoles formation in Nile grass type II diabetic rats

Aihara K., Nakazawa Y., Takeda S., Hatsusaka N., Onouchi T., Hiramatsu N., Nagata M., Nagai N., Funakoshi-Tago M., Yamamoto N., Sasaki H.

Medical Molecular Morphology 56 （ 4 ） 274 - 287 2023年12月

ISSN 18601480

Regulation of ion and water microcirculation within the lens is tightly controlled through aquaporin channels and connexin junctions. However, cataracts can occur when the lens becomes cloudy. Various factors can induce cataracts, including diabetes which is a well-known cause. The most common phenotype of diabetic cataracts is a cortical and/or posterior subcapsular opacity. In addition to the three main types and two subtypes of cataracts, a vacuole formation is frequently observed; however, their origin remains unclear. In this study, we focused on the aquaporins and connexins involved in diabetes-induced cataracts and vacuoles in Nile grass type II diabetes. The results showed that the expression of aquaporin 0 and aquaporin 5 increased, and that of connexin 43 decreased in diabetic rat lenses. Additionally, aquaporin 0 and 5 were strongly localized in peripheral of vacuoles, suggesting that aquaporins are involved in vacuoles formation. Transillumination photography revealed large vacuoles at the tip of the Y-suture in the anterior capsule of the diabetic lens, and several small vacuoles were observed in the posterior capsule. Within the vacuoles, cytoplasmic degradation and aggregation of fibrous material were observed. Our findings suggest that aquaporins are potential candidate proteins for preventing vacuole formation.

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Hesperetin treatment attenuates glycation of lens proteins and advanced-glycation end products generation

Doki Y., Nakazawa Y., Morishita N., Endo S., Nagai N., Yamamoto N., Tamura H., Funakoshi-Tago M.

Molecular Medicine Reports 27 （ 5 ） 2023年05月

ISSN 17912997

Advanced glycation end products (AGEs) in lens proteins increase with aging, thus inducing cataracts and/or presbyopia. Hesperetin (Hst), which is an abundant plant flavanone largely derived from citrus species, and its derivatives attenuate cataracts and presbyopia in vivo and in vitro; however, no reports have described its effects on AGE formation in lens proteins. The present study demonstrated that AGEs in lens proteins increase with age in mice. Additionally, it showed that Hst can prevent AGEs and N(ϵ)-carboxymethyl-lysine generation and modification of lens proteins using in vitro in human lens epithelial cell lines and ex vivo in mouse lens organ cultures. Furthermore, treatment with Hst prevented lens hardening and decreased chaperone activity in lens proteins. These results suggested that Hst and its derivatives are good candidates for the prevention of presbyopia and cataracts.

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The indispensable role of the RNA helicase DDX5 in tumorigenesis induced by the myeloproliferative neoplasm-associated JAK2V617F mutant

Takeda K., Tago K., Funakoshi-Tago M.

Cellular Signalling （Cellular Signalling） 102 2023年02月

ISSN 08986568

A point mutation (V617F) in the Janus kinase 2 (JAK2) gene results in the production of disorderly activated tyrosine kinase, which causes myeloproliferative neoplasms (MPN). We herein demonstrated that the RNA helicase DDX5 was highly expressed at the mRNA and protein levels through the activation of signal transducer and activator of transcription 5 (STAT5) in Ba/F3 cells expressing a JAK2V617F mutant and erythropoietin receptor (V617F/EpoR cells) and MPN patient-derived HEL cells. A treatment with the JAK1/2 inhibitor, ruxolitinib and STAT5 inhibitor, pimozide significantly inhibited DDX5 mRNA expression and enhanced the degradation of DDX5 in these cells, suggesting that the JAK2V617F mutant positively regulates DDX5 mRNA expression and DDX5 protein stability by activating STAT5. The knockdown of DDX5 specifically inhibited the activation of mechanistic target of rapamycin (mTOR) in V617F/EpoR cells and HEL cells and significantly suppressed the proliferation of these cells. Furthermore, the knockdown of DDX5 markedly suppressed tumorigenesis, splenomegaly, and liver hypertrophy caused by an inoculation of V617F/EpoR cells in nude mice. Collectively, these results revealed that JAK2V617F exhibits transforming activity by inducing the expression of DDX5 in a STAT5-dependent manner, indicating the potential of the JAK2V617F/STAT5/DDX5 axis as a therapeutic target in the treatment of MPN.

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Identification of DDX5 as an indispensable activator of the glucocorticoid receptor in adipocyte differentiation.

Hokimoto S, Funakoshi-Tago M, Tago K.

FEBS J. 2022年09月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り

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Coffee ingredients, hydroquinone, pyrocatechol, and 4-ethylcatechol exhibit anti-inflammatory activity through inhibiting NF-κB and activating Nrf2

Funakoshi-Tago M., Matsutaka M., Hokimoto S., Kobata K., Tago K., Tamura H.

Journal of Functional Foods （Journal of Functional Foods） 90 2022年03月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 17564646

Pyrocatechol is a coffee ingredient that exhibits anti-inflammatory activity. We herein identified hydroquinone and 4-ethylcatechol as novel coffee ingredients inhibiting LPS-induced inflammatory responses. Similar to pyrocatechol, hydroquinone and 4-ethylcatechol significantly inhibited LPS-induced nitric oxide (NO) production and CCL2 secretion by suppressing the mRNA expression of iNOS and CCL2 in murine macrophage-like RAW264.7 cells. These ingredients also inhibited the LPS-induced activation of NF-κB, a pivotal transcription factor in inflammation, by preventing its nuclear localization, and induced the expression of Nrf2, a transcription factor negatively regulating LPS-induced inflammation. By utilizing Keap1−/−MEFs reconstituted with Keap1 mutants in which major cysteine residues were substituted, we found that Cys151 in Keap1 was a critical sensor for pyrocatechol, hydroquinone, and 4-ethylcatechol to induce Nrf2 expression. However, the amounts of hydroquinone and 4-ethylcatechol in the coffee decoction were markedly lower than that of pyrocatechol, suggesting that pyrocatechol is the main coffee ingredient exhibiting anti-inflammatory activity.

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A bis-pyridinium fullerene derivative induces apoptosis through the generation of ROS in BCR-ABL-positive leukemia cells

Sumi K., Tago K., Nakazawa Y., Takahashi K., Ohe T., Mashino T., Funakoshi-Tago M.

European Journal of Pharmacology （European Journal of Pharmacology） 916 2022年02月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00142999

A fusion protein, Breakpoint cluster region-Abelson (BCR-ABL) is responsible for the development of chronic myeloid leukemia (CML) and acute lymphocytic leukemia (ALL). Inhibitors against BCR-ABL are effective for the treatment of leukemia; however, a gatekeeper mutation (T315I) in BCR-ABL results in resistance to these inhibitors, which markedly impedes their efficacy. We herein demonstrated that a bis-pyridinium fullerene derivative (BPF) significantly induced apoptosis in human CML-derived K562 cells and ALL-derived SUP-B15 cells via the generation of reactive oxygen species (ROS). BPF reduced the expression of Bcr-Abl mRNA by inhibiting expression of c-Myc through ROS production. BPF also accelerated protein degradation of BCR-ABL through ROS production. Furthermore, BPF down-regulated the expression of not only BCR-ABL but also T315I-mutated BCR-ABL in ROS-dependent manner. As a result, BPF effectively induced apoptosis in transformed Ba/F3 cells expressing both BCR-ABL and T315I-mutated BCR-ABL. Collectively, these results indicate the potential of BPF as an effective leukemia drug that overcomes resistance to BCR-ABL inhibitors.

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Novel Mechanism by a Bis-Pyridinium Fullerene Derivative to Induce Apoptosis by Enhancing the MEK-ERK Pathway in a Reactive Oxygen Species-Independent Manner in BCR-ABL-Positive Chronic Myeloid Leukemia-Derived K562 Cells

Sumi K., Tago K., Nakazawa Y., Takahashi K., Ohe T., Mashino T., Funakoshi-Tago M.

International Journal of Molecular Sciences 23 （ (2) ） 749 2022年01月

研究論文（学術雑誌）, 最終著者, 責任著者, 査読有り, ISSN 16616596

In the treatment of breakpoint cluster region-Abelson (BCR-ABL)-positive chronic myeloid leukemia (CML) using BCR-ABL inhibitors, the appearance of a gatekeeper mutation (T315I) in BCR-ABL is a serious issue. Therefore, the development of novel drugs that overcome acquired resistance to BCR-ABL inhibitors by CML cells is required. We previously demonstrated that a bis-pyridinium fullerene derivative (BPF) induced apoptosis in human chronic myeloid leukemia (CML)-derived K562 cells partially through the generation of reactive oxygen species (ROS). We herein show that BPF enhanced the activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-extracellular signal-regulated kinase (MEK-ERK) pathway in a ROS-independent manner. BPF-induced apoptosis was attenuated by trametinib, suggesting the functional involvement of the MEK-ERK pathway in apoptosis in K562 cells. In addition, the constitutive activation of the MEK-ERK pathway by the enforced expression of the BRAFV600E mutant significantly increased the sensitivity of K562 cells to BPF. These results confirmed for the first time that BPF induces apoptosis in K562 cells through dual pathways—ROS production and the activation of the MEK-ERK pathway. Furthermore, BPF induced cell death in transformed Ba/F3 cells expressing not only BCR-ABL but also T315I mutant through the activation of the MEK-ERK pathway. These results indicate that BPF is as an effective CML drug that overcomes resistance to BCR-ABL inhibitors.

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Identification of DDX5 as an indispensable activator of the glucocorticoid receptor in adipocyte differentiation

Hokimoto S., Funakoshi-Tago M., Tago K.

FEBS Journal （FEBS Journal） 2022年

ISSN 1742464X

The expression of CCAAT/enhancer-binding protein (C/EBP) family members and peroxisome proliferator-activated receptor γ (PPAR γ) is essential for the differentiation of pre-adipocyte 3T3-L1 cells into mature adipocytes induced by a combined stimulation with dexamethasone, 3-isobutyl-1-methylxanthine and insulin (DMI). We herein demonstrated that the RNA helicase DDX5, the expression of which was induced by DMI, played an important role in the adipocyte differentiation of 3T3-L1 cells. The DMI-induced accumulation of lipid droplets and expression of adipocyte markers in 3T3-L1 cells were significantly inhibited by the knockdown of DDX5. The knockdown of DDX5 interfered with the expressional induction of C/EBPδ, which was the first to be induced in the transcription factor cascade, and inhibited the subsequent expression of the other transcription factors, C/EBPβ, PPARγ and C/EBPα. DDX5 interacted with the glucocorticoid receptor (GR), which induced the expression of C/EBPδ. The knockdown of DDX5 failed to induce the nuclear translocation of GR, suggesting the essential role of DDX5 in the early stage of adipocyte differentiation. Furthermore, the reconstitution of DDX5, but not the DDX5 mutant (K144N) lacking RNA helicase activity, restored DMI-induced GR activation and adipocyte differentiation in 3T3-L1 cells in which DDX5 was knocked down, confirming that the RNA helicase activity of DDX5 is essential for adipogenesis. Collectively, these results revealed for the first time that DDX5 is necessary for GR activation and plays an essential role in early adipocyte differentiation.

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Capsaicin attenuates TGFβ2-induced epithelial-mesenchymal-transition in lens epithelial cells in vivo and in vitro

Sugiyama Y., Nakazawa Y., Sakagami T., Kawata S., Nagai N., Yamamoto N., Funakoshi-Tago M., Tamura H.

Experimental Eye Research （Experimental Eye Research） 213 2021年12月

研究論文（学術雑誌）, 査読有り, ISSN 00144835

Posterior capsule opacification (PCO), the most common complication of cataract surgery occurring in 20–50% of patients after 2–5 years of cataract surgery, is a major problem in the aging society. The epithelial-mesenchymal transition (EMT) of lens epithelial cells after cataract surgery has been proposed as a major cause of PCO. Capsaicin, widely used as a food additive and analgesic agent, is a major pungent ingredient in red pepper. Although the effect of capsaicin on EMT has been reported in cancer cells, the biological reaction of capsaicin was unique in each cell type, and there have been no reports describing its effects on EMT earlier. In this study, we demonstrated that treatment with capsaicin inhibited TGFβ2-induced EMT in vitro lens epithelial cells and ex vivo explant lens epithelial cells. Furthermore, eye drops of capsaicin inhibited the PCO model mice in vivo. Finally, we showed that capsaicin inhibited non-canonically induced Smad2/3 activation via suppression of EGFR activation and ERK phosphorylation. Our findings indicate that capsaicin and its derivatives are good candidate compounds for preventing PCO after cataract surgery.

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K15 promoter-driven enforced expression of NKIRAS exhibits tumor suppressive activity against the development of DMBA/TPA-induced skin tumors

Tago K., Ohta S., Aoki-Ohmura C., Funakoshi-Tago M., Sashikawa M., Matsui T., Miyamoto Y., Wada T., Oshio T., Komine M., Matsugi J., Furukawa Y., Ohtsuki M., Yamauchi J., Yanagisawa K.

Scientific Reports （Scientific Reports） 11 （ 1 ） 2021年12月

研究論文（学術雑誌）, 共著, 査読有り

NKIRAS1 and NKIRAS2 (also called as κB-Ras) were identified as members of the atypical RAS family that suppress the transcription factor NF-κB. However, their function in carcinogenesis is still controversial. To clarify how NKIRAS acts on cellular transformation, we generated transgenic mice in which NKIRAS2 was forcibly expressed using a cytokeratin 15 (K15) promoter, which is mainly activated in follicle bulge cells. The ectopic expression of NKIRAS2 was mainly detected in follicle bulges of transgenic mice with NKIRAS2 but not in wild type mice. K15 promoter-driven expression of NKIRAS2 failed to affect the development of epidermis, which was evaluated using the expression of K10, K14, K15 and filaggrin. However, K15 promoter-driven expression of NKIRAS2 effectively suppressed the development of skin tumors induced by treatment with 7,12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol 13-acetate (TPA). This observation suggested that NKIRAS seemed to function as a tumor suppressor in follicle bulges. However, in the case of oncogenic HRAS-driven cellular transformation of murine fibroblasts, knockdown of NKIRAS2 expression drastically suppressed HRAS-mutant-provoked cellular transformation, suggesting that NKIRAS2 was required for the cellular transformation of murine fibroblasts. Furthermore, moderate enforced expression of NKIRAS2 augmented oncogenic HRAS-provoked cellular transformation, whereas an excess NKIRAS2 expression converted its functional role into a tumor suppressive phenotype, suggesting that NKIRAS seemed to exhibit a biphasic bell-shaped enhancing effect on HRAS-mutant-provoked oncogenic activity. Taken together, the functional role of NKIRAS in carcinogenesis is most likely determined by not only cellular context but also its expression level.

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The indole-hydantoin derivative exhibits anti-inflammatory activity by preventing the transactivation of NF-κB through the inhibition of NF-κB p65 phosphorylation at Ser276

Lin X., Tago K., Okazaki N., So T., Takahashi K., Mashino T., Tamura H., Funakoshi-Tago M.

International Immunopharmacology （International Immunopharmacology） 100 2021年11月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 15675769

Indole- and hydantoin-based derivatives both exhibit anti-inflammatory activity, suggesting that the structures of indole and hydantoin are functional for this activity. In the present study, we synthesized two types of indole-hydantoin derivatives, IH-1 (5-(1H-indole-3-ylmethylene) imidazolidine-2,4-dione) and IH-2 (5-(1H-indole-3-ylmethyl) imidazolidine-2,4-dione) and examined their effects on LPS-induced inflammatory responses in murine macrophage-like RAW264.7 cells. LPS-induced inflammatory responses were not affected by indole, hydantoin, or IH-2. In contrast, IH-1 significantly inhibited the LPS-induced production of nitric oxide (NO) and secretion of CCL2 and CXCL1 by suppressing the mRNA expression of inducible NO synthase (iNOS), CCL2, and CXCL1. IH-1 markedly inhibited the LPS-induced activation of NF-κB without affecting the degradation of IκBα or nuclear translocation of NF-κB. IH-1 markedly attenuated the transcriptional activity of NF-κB by suppressing the LPS-induced phosphorylation of the NF-κB p65 subunit at Ser276. Furthermore, IH-1 prevented the LPS-induced interaction of NF-κB p65 subunit with a transcriptional coactivator, cAMP response element-binding protein (CBP). Collectively, these results revealed the potential of the novel indole-hydantoin derivative, IH-1 as an anti-inflammatory drug.

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