Disruption of Heat Shock Protein 90 (Hsp90)-Protein Kinase Cδ (PKCδ) Interaction by (-)-Maackiain Suppresses Histamine H1 Receptor Gene Transcription in HeLa Cells

Structure-activity relationship studies of pyrogallol as a calcineurin/NFAT signaling suppressor

Previously, we have shown that pyrogallol alleviated nasal symptoms and suppressed IL-9 gene up-regulation in allergy model rats by inhibiting calcineurin/NFAT signaling. As pyrogallol has antioxidative activity, it may be responsible for inhibiting calcineurin/NFAT signaling-mediated IL-9 gene expression. However, the relationship between antioxidative activity and suppression of IL-9 gene expression has not been elucidated yet. Here, we conducted the structure-activity relationship studies of pyrogallol and its structurally related compounds to understand the mechanism of IL-9 gene suppression by pyrogallol. 2, 2-Diphenyl-1-picrylhydrazyl radical scavenging assay showed that the antioxidative activity of catechol, resorcinol, phloroglucinol, and gallic acid is 60.1%, 10.4%, 18.8%, and 113.5% of pyrogallol, respectively. Catechol, resorcinol, and phloroglucinol did not suppress NFAT dephosphorylation. Gallic acid suppressed dephosphorylation of NFAT. Gallic acid also suppressed ionomycin-induced up-regulation of IL-9 gene expression with the IC50 value of 82.6 μM. However, catechol, resorcinol and phloroglucinol showed no suppressive activity. In addition, using gallic acid-immobilized beads, we isolated and identified Poly(U)-binding-splicing factor 60 (PUF60) as a pyrogallol binding protein. These results suggest that the antioxidative activity of pyrogallol is not likely to be the mechanism of IL-9 gene suppression. Data also suggest that PUF60 is one of its target molecules responsible for the suppression of calcineurin/NFAT signaling by pyrogallol.

Identification and Characterization of Chemical Constituents from Ammopiptanthus nanus Stem and Their Metabolites in Rats by UHPLC-Q-TOF-MS/MS

Ammopiptanthus nanus as a Kirgiz medicine is widely used for the treatment of frostbite and chronic rheumatoid arthritis. However, due to a lack of systematic research on the chemical components of A. nanus and their metabolites, the bioactive components in it remain unclear. Herein, a reliable strategy based on UHPLC-Q-TOF-MS/MS was established to comprehensively analyze the chemical components and their metabolites in vivo. In total, 59 compounds were identified from A. nanus stem extract, among which 14 isoflavones, 10 isoprenylated isoflavones, 4 polyhydroxy flavonoids, 9 alkaloids and 1 polyol were characterized for the first time. After oral administration of A. nanus stem extract, 30 prototype constituents and 28 metabolites (12 phase I and 16 phase II metabolites) were speculated on and identified in rat serum, urine and feces. Furthermore, the metabolic pathways of the chemical components were systematically analyzed and proposed. In conclusion, the chemical components from A. nanus stem and their metabolites in vivo were first studied, which may provide useful chemical information for further study on the effective material basis and pharmacological mechanism of A. nanus.

Function and Role of Histamine H1 Receptor in the Mammalian Heart

Histamine can change the force of cardiac contraction and alter the beating rate in mammals, including humans. However, striking species and regional differences have been observed. Depending on the species and the cardiac region (atrium versus ventricle) studied, the contractile, chronotropic, dromotropic, and bathmotropic effects of histamine vary. Histamine is present and is produced in the mammalian heart. Thus, histamine may exert autocrine or paracrine effects in the mammalian heart. Histamine uses at least four heptahelical receptors: H1, H2, H3 and H4. Depending on the species and region studied, cardiomyocytes express only histamine H1 or only histamine H2 receptors or both. These receptors are not necessarily functional concerning contractility. We have considerable knowledge of the cardiac expression and function of histamine H2 receptors. In contrast, we have a poor understanding of the cardiac role of the histamine H1 receptor. Therefore, we address the structure, signal transduction, and expressional regulation of the histamine H1 receptor with an eye on its cardiac role. We point out signal transduction and the role of the histamine H1 receptor in various animal species. This review aims to identify gaps in our knowledge of cardiac histamine H1 receptors. We highlight where the published research shows disagreements and requires a new approach. Moreover, we show that diseases alter the expression and functional effects of histamine H1 receptors in the heart. We found that antidepressive drugs and neuroleptic drugs might act as antagonists of cardiac histamine H1 receptors, and believe that histamine H1 receptors in the heart might be attractive targets for drug therapy. The authors believe that a better understanding of the role of histamine H1 receptors in the human heart might be clinically relevant for improving drug therapy.

Betuletol, a Propolis Component, Suppresses IL-33 Gene Expression and Effective against Eosinophilia

Propolis, a resinous substance produced by honeybees, has been used in folk medicine since ancient times due to its many biological benefits such as antitumor, antioxidant, antimicrobial, anti-inflammatory, and immunomodulatory effects. Propolis contains flavonoids, terpenoids, aromatic aldehydes, and alcohols, which vary with different climate and environmental conditions. In our study, we examined the antiallergic activity of Brazilian green propolis (BGP) and isolated the active compound that can suppress an allergy-sensitive gene, IL-33, expression and eosinophilia. Ethanolic extract of BGP freeze-dried powder was fractionated with several solvent systems, and the active fractions were collected based on activity measurement. The single active compound was found by thin-layer chromatography. Using column chromatography and NMR, the active compound was isolated and identified as 3,5,7-trihydroxy-6,4’-dimethoxyflavone, also known as betuletol. Further, the antiallergic activity of that has been examined in PMA-induced up-regulation of IL-33 gene expression in Swiss 3T3 cells. Our data showed the IL-33 gene suppression both by BGP and the isolated active compound, betuletol. We also found that betuletol suppressed ERK phosphorylation, suggesting it could be effective in suppressing IL-33 mediated eosinophilic chronic inflammation and will provide new insights to develop potent therapeutics against allergic inflammations.

Maackiain protects against sepsis via activating AMPK/Nrf2/HO-1 pathway

Sepsis is a life-threatening medical condition caused by infection-triggered aberrant immune responses, leading to host tissue and organ injury. Despite advances in medical interventions, the mortality rate for septic shock remains high. Recent studies highlight the role of oxidative stress in the occurrence and development of sepsis, providing a potential therapeutic target for preventing sepsis-associated organ injury. In this study, we showed that Maackiain, a natural compound isolated from Sophora flavescens, exerted a protective role in a cecal ligation and puncture (CLP)-induced murine model of sepsis. Maackiain treatment reduced organ injury, and mitigated systematic inflammation and oxidative stress in septic mice. Maackiain also reduced the levels of inflammatory cytokines and reactive oxygen species (ROS) in RAW264.7 macrophage cells stimulated with lipopolysaccharide (LPS). We further demonstrated that Maackiain initiated activation of nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway in RAW264.7 cells in an AMP-activated protein kinase (AMPK)-dependent way. Moreover, inhibition of AMPK/Nrf2 axis abrogated the anti-inflammatory and anti-oxidant effects of Maackiain both in vitro and in vivo. Collectively, our study indicates that Maackiain treatment inhibits inflammatory response and oxidative stress via activation of AMPK/Nrf2/HO-1 pathway, thus exerting a protective effect against sepsis, providing an alternative option for sepsis prevention.

Anti-adipogenic activity of maackiain and ononin is mediated via inhibition of PPARγ in human adipocytes

Obesity is a global health burden for which we do not yet have effective treatments for prevention or therapy. Plants are an invaluable source of bioactive leads possessing anti-adipogenic potential. Ethnopharmacological use of Ononis spinosa L. roots (OSR) for treatment of obesity and metabolic disorders requires а scientific rationale. The current study examined the anti-adipogenic capacity of OSR and its secondary metabolites ononin (ONON) and maackiain (MACK) in human adipocytes as an in vitro model of obesity. Both ONON and MACK diminished lipid accumulation during adipocyte differentiation. Molecular docking analysis exposed the potential interactions between MACK or ONON and target regulatory adipogenic proteins. Furthermore, results from an RT-qPCR analysis disclosed significant upregulation of AMPK by MACK and ONON treatment. In addition, ONON increased SIRT1, PI3K and ACC mRNA expression, while MACK notably downregulated CEBPA, AKT, SREBP1, ACC and ADIPOQ. The protein level of PI3K, C/EBPα, PPARγ and adiponectin was reduced upon MACK treatment in a concentration-dependent manner. Similarly, ONON suppressed PI3K, PPARγ and adiponectin protein abundance. Finally, our study provides evidence that ONON exerts anti-adipogenic effect by upregulation of SIRT1 and inhibition of PI3K, PPARγ and adiponectin, while MACK induced strong inhibitory effect on adipogenesis via hampering PI3K, PPARγ/C/EBPα signaling and anti-lipogenic effect through downregulation of SREBP1 and ACC. Even though OSR does not hamper adipogenic differentiation, it could be exploited as a source of natural leads with anti-adipogenic potential. The multidirectional mechanism of action of MACK warrant further validation in the context of in vivo obesity models.

Metabolomic profiling of M. speciosa champ at different growth stages

Millettia speciosa Champ (M. speciosa) is an edible food and folk medicine and extracts from its roots exhibit a hepatoprotective effect. However, its metabolic growth process and the best harvest time have not been reported. This study systematically evaluated the metabolomic profiling of M. speciosa root extracts at different growth stages through the UPLC-Q-TOF-MS, nuclear magnetic resonance (NMR) and An orthogonal partial least squares-discriminant analysis (OPLS-DA). The results revealed there were significant differences among extracts from six ages of M. speciosa, and 110 compounds were identified. Pharmacological studies showed that 5-year and 20-year old M. speciosa roots may exhibit higher fat-lowering effects, while 5-year-old (M.s-5Y) showed better hepatoprotective activity in high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) mice. Hence, our study suggested that M.s-5Y may have potent efficacy in ameliorating NAFLD, which might be useful in determining the optimum time to harvest M. speciosa.

Maackiain Protects the Kidneys of Type 2 Diabetic Rats via Modulating the Nrf2/HO-1 and TLR4/NF-κB/Caspase-3 Pathways

BACKGROUND

Type 2 diabetes (T2D) is aglobal health burden that accounts for about 90% of all cases of diabetes. Injury to the kidneys is aserious complication of type 2 diabetes. Maackiain, apterocarpan extracted from roots of Sophora flavescens, has been traditionally used for various disease conditions. However, nothing is known about its possible potential effect on HFD/STZ-T2D-induced nephrotoxicity.

METHODS

In this study, T2D rat model is created by high-fat diet (HFD) for 2 weeks with injection of asingle dose of streptozotocin (35mg/kg body weight). T2D rats were orally administered with maackiain (10 and 20mg/kg body weight) for 7 weeks.

RESULTS

Maackiain suppressed T2D-induced alterations in metabolic parameters, lipid profile and kidney functionality markers. By administering 10 and 20mg/kg maackiain to T2D rats, it was able to reduce lipid peroxidation while improving antioxidant levels (SOD, CAT, and GSH). Furthermore, the present study demonstrated the molecular mechanisms through which maackiain attenuated T2D-induced oxidative stress (mRNA: Nrf2, Nqo-1, Ho-1, Gclc and Gpx-1; protein: NRF2, NQO-1, HO-1 and NOX-4), inflammation (mRNA: Tlr, Myd88, IκBα, Mcp-1, Tgf-β, col4, Icam1, Vcam1 and E-selectin; Protein: TLR4, MYD88, NF-κB, IκBα, MCP-1; levels: TNF-α and MCP-1) and apoptosis (mRNA: Bcl-2, Bax, Bad, Apaf-1, Caspase-9 and Caspase-3; protein: Bcl-2, Bax, Caspase-3 and Caspase-9) mediated renal injury. Additionally, significant improvement in kidney architecture was observed after treatment of diabetic rats with 10 or 20mg/kg maackiain.

CONCLUSION

Maackiain protects the kidney by decreasing oxidative stress, inflammation, and apoptosis to preserve normal renal function in type 2 diabetes.

Patho-Pharmacological Research of Anti-allergic Natural Products Targeting Antihistamine-Sensitive and -Insensitive Allergic Mechanisms

Histamine H₁ receptor (H1R) has a special up-regulation mechanism by the stimulation of H1R, mediated by protein kinase C-delta (PKCδ) signaling and H1R gene expression, resulting increase in H1R signaling. Increase in H1R mRNA in nasal mucosa was induced after the provocation of nasal hypersensitivity model rats and suppressed by the pre-treatment of antihistamines. Improvement of nasal symptoms and suppression of H1R mRNA expression in nasal mucosa were also observed by the pre-treatment of antihistamines in pollinosis patients. Elucidation of a correlation between symptoms and H1R mRNA level suggests that H1R gene is an allergic disease (AD)-susceptibility gene, targeted by antihistamines. Similar to antihistamines, pre-treatment of Kujin extract, an anti-allergic Kampo medicine improved nasal symptoms and suppressed H1R mRNA expression in nasal hypersensitivity model rats. (-)-Maackiain targeting heat shock protein 90 (Hsp90) was isolated as an inhibitor of PKCδ signaling-mediated H1R gene expression from Kujin extract. In addition to H1R-mediated activation of H1R gene expression as the first mechanism, nuclear factor of activated T-cells (NFAT)-mediated IL-9 gene expression is suggested to participate to allergic symptoms as the second mechanism insensitive to antihistamines. Pyrogallol and proanthocyanidin suppressing IL-9 gene expression were discovered from Awa-tea and lotus root knots, respectively. Combination therapy using medicines suppressing both H1R gene expression and IL-9 gene expression is promising for outstanding alleviation of AD. Multifactorial diseases involving H1R gene expression may be treated by the combination therapy with antihistamine and complementary drugs, and diseases involving PKCδ signaling may be treated by drugs targeting Hsp90.

Molecular Signaling and Transcriptional Regulation of Histamine H1 Receptor Gene

Histamine-activated histamine H₁ receptor (H1R) signaling regulates many gene expressions, mainly through the protein kinase C (PKC)/extracellular signal-regulated kinases (ERK) signaling. Involvement of other signaling, including NF-κB, Wnt, RUNX-2, and Rho A signaling was also demonstrated. In addition, cAMP production through the activation of H1R signaling was reported. H1R gene itself is also up-regulated by the activation of H1R signaling with histamine. Here, we review our recent findings in the molecular signaling and transcriptional regulation of the H1R gene. Stimulation with histamine up-regulates H1R gene expression through the activation of H1R in HeLa cells. The PKCδ/ERK/poly(ADP)ribosyl transferase-1 (PARP-1) signaling was involved in this up-regulation. Heat shock protein 90 also plays an important role in regulating PKCδ translocation. Promoter analyses revealed the existence of two promoters in the human H1R gene in HeLa cells. H1R-activated H1R gene up-regulation in response to histamine was also observed in U373 astroglioma cells. However, this up-regulation was mediated not through the PKCδ signaling but possibly through the PKCα signaling. In addition, the promoter region responsible for histamine-induced H1R gene transcription in U373 cells was different from that of HeLa cells. These findings suggest that the molecular signaling and transcriptional regulation of the H1R gene are different between neuronal cells and non-neuronal cells.

Signaling Pathway of Histamine H1 Receptor-Mediated Histamine H1 Receptor Gene Upregulation Induced by Histamine in U-373 MG Cells

Histamine H₁ receptor (H1R) is one of the targets of histamine in the nervous system and the peripheral tissues. Protein kinase Cδ (PKCδ) signaling is involved in histamine-induced upregulation of H1R gene expression in HeLa cells. Histamine also upregulates H1R gene expression in U-373 MG cells. However, the molecular signaling of this upregulation is still unclear. Here, we investigated the molecular mechanism of histamine-induced H1R gene upregulation in U-373 MG cells. Histamine-induced H1R gene upregulation was inhibited by H1R antagonist d-chlorpheniramine, but not by ranitidine, ciproxifan, or JNJ77777120, and H2R, H3R, or H4R antagonists, respectively. Ro-31-8220 and Go6976 also suppressed this upregulation, however, the PKCδ selective inhibitor rottlerin and the PKCβ selective inhibitor Ly333531 did not. Time-course studies showed distinct kinetics of H1R gene upregulation in U-373 MG cells from that in HeLa cells. A promoter assay revealed that the promoter region responsible for H1R gene upregulation in U-373 MG cells was different from that of HeLa cells. These data suggest that the H1R-activated H1R gene expression signaling pathway in U-373 MG cells is different from that in HeLa cells, possibly by using different promoters. The involvement of PKCα also suggests that compounds that target PKCδ could work as peripheral type H1R-selective inhibitors without a sedative effect.

Effects of Syo-seiryu-to and Its Constituent Crude Drugs on Phorbol Ester-Induced Up-Regulation of IL-33 and Histamine H1 Receptor mRNAs in Swiss 3T3 and HeLa Cells

Syo-seiryu-to (SST) is a traditional herbal medicine that has been used clinically to treat allergic rhinitis (AR) in Japan. SST improves acute symptoms, such as sneezing and rhinorrhea, as well as chronic symptoms, such as nasal obstruction, in patients with AR. However, its therapeutic mechanisms remain unknown. We examined the effects of SST and eight constituent crude drugs on phorbol 12-myristate-13-acetate (PMA)-induced gene up-regulation of IL-33 and histamine H1 receptor (H1R), which are responsible for the pathogenesis of AR. We found that SST and its crude drugs, except for Pinellia tuber, significantly and dose-dependently suppressed PMA-induced both IL-33 and H1R mRNA up-regulation in vitro. The half-maximal inhibitory concentration values of the seven crude drugs to inhibit PMA-induced IL-33 mRNA up-regulation were correlated with those related to H1R mRNA up-regulation, suggesting that they act on a common signal molecule. These results suggest that SST improves nasal congestion that is induced by IL-33-related eosinophil infiltration and inhibits sneezing and rhinorrhea that are induced by H1R-mediated histamine signaling in the nasal mucosa of AR patients through its inhibition of a common molecule in the gene expression pathways of IL-33 and H1R. The results could explain the advantages of traditional herbal medicine, in which mixing various crude drugs not only acts on a common target to enhance its pharmacological action, similar to the effect of a high concentration of a single crude extract but also has the benefit of reducing the side effects of each crude drug.

Biosynthesis, total synthesis, structural modifications, bioactivity, and mechanism of action of the quinone-methide triterpenoid celastrol

Celastrol, a quinone-methide triterpenoid, was extracted from Tripterygium wilfordii Hook. F. in 1936 for the first time. Almost 70 years later, it is considered one of the molecules most likely to be developed into modern drugs, as it exhibits notable bioactivity, including anticancer and anti-inflammatory activity, and exerts antiobesity effects. In addition, the molecular mechanisms underlying its bioactivity are being widely studied, which offers new avenues for its development as a pharmaceutical reagent. Owing to its potential therapeutic effects and unique chemical structure, celastrol has attracted considerable interest in the fields of organic, biosynthesis, and medicinal chemistry. As several steps in the biosynthesis of celastrol have been revealed, the mechanisms of key enzymes catalyzing the formation and postmodifications of the celastrol scaffold have been gradually elucidated, which lays a good foundation for the future heterogeneous biosynthesis of celastrol. Chemical synthesis is also an effective approach to obtain celastrol. The total synthesis of celastrol was realized for the first time in 2015, which established a new strategy to obtain celastroid natural products. However, owing to the toxic effects and suboptimal pharmacological properties of celastrol, its clinical applications remain limited. To search for drug-like derivatives, several structurally modified compounds were synthesized and tested. This review focuses primarily on the latest research progress in the biosynthesis, total synthesis, structural modifications, bioactivity, and mechanism of action of celastrol. We anticipate that this paper will facilitate a more comprehensive understanding of this promising compound and provide constructive references for future research in this field.

Maackiain dampens osteoclastogenesis via attenuating RANKL-stimulated NF-κB signalling pathway and NFATc1 activity

Osteolytic diseases are typified by over‐enhanced formation and resorbing function of osteoclasts and have a major impact on human health. Inhibition of osteoclastic differentiation and function is a key strategy for clinical therapy of osteolytic conditions. Maackiain is a natural compound extracted from Sophora flavescens, which has been applied to anti‐allergic and anti‐tumour treatments. The present results showed that Maackiain could restrain receptor activator of nuclear factor‐κB ligand (RANKL)‐stimulated osteoclast formation and hydroxyapatite resorption dose‐dependently, and interrupt the structures of F‐actin belts in the mature osteoclasts. It also repressed the expressions of osteoclast‐specific genes and proteins. Furthermore, Maackiain could inhibit RANKL‐stimulated NF‐κB and calcium signalling pathways, and dampen Nuclear factor of activated T cell cytoplasmic 1 activity, protein expression and translocation into the nucleus. These results revealed that Maackiain may have a potential therapeutic effect on osteoclast‐related disorders.

Maackiain Ameliorates 6-Hydroxydopamine and SNCA Pathologies by Modulating the PINK1/Parkin Pathway in Models of Parkinson's Disease in Caenorhabditis elegans and the SH-SY5Y Cell Line

The movement disorder Parkinson's disease (PD) is the second most frequently diagnosed neurodegenerative disease, and is associated with aging, the environment, and genetic factors. The intracellular aggregation of α-synuclein and the loss of dopaminergic neurons in the substantia nigra pars compacta are the pathological hallmark of PD. At present, there is no successful treatment for PD. Maackiain (MK) is a flavonoid extracted from dried roots of Sophora flavescens Aiton. MK has emerged as a novel agent for PD treatment that acts by inhibiting monoamine oxidase B. In this study, we assessed the neuroprotective potential of MK in Caenorhabditis elegans and investigated possible mechanism of this neuroprotection in the human SH-SY5Y cell line. We found that MK significantly reduced dopaminergic neuron damage in 6-hydroxydopamine (6-OHDA)-exposed worms of the BZ555 strain, with corresponding improvements in food-sensing behavior and life-span. In transgenic worms of strain NL5901 treated with 0.25 mM MK, the accumulation of α-synuclein was diminished by 27% (p < 0.01) compared with that in untreated worms. Moreover, in worms and the SH-SY5Y cell line, we confirmed that the mechanism of MK-mediated protection against PD pathology may include blocking apoptosis, enhancing the ubiquitin-proteasome system, and augmenting autophagy by increasing PINK1/parkin expression. The use of small interfering RNA to downregulate parkin expression in vivo and in vitro could reverse the benefits of MK in PD models. MK may have considerable therapeutic applications in PD.

Elucidation of Inverse Agonist Activity of Bilastine

H1-antihistamines antagonize histamine and prevent it from binding to the histamine H1 receptor (H1R). Some of them also act as inverse agonists, which are more potent than pure antagonists because they suppress the constitutive H1R activity. Bilastine is a non-sedative antihistamine which is one of the most satisfy the requirements for oral antihistamines. However, there is no information to show the inverse agonist activity of bilastine including inositol phosphates accumulation, and its inverse agonist activity is yet to be elucidated. Here we evaluated whether bilastine has inverse agonist activity or not. Intracellular calcium concentration was measured using Fluo-8. Inositol phosphates accumulation was assayed using [3H]myo-inositol. The H1R mRNA level was measured using real-time RT-PCR. At rest, Ca2+ oscillation was observed, indicating that H1R has intrinsic activity. Bilastine attenuated this fluorescence oscillation. Bilastine suppressed the increase in IPs formation in a dose-dependent manner and it was about 80% of the control level at the dose of 3 μM. Bilastine also suppressed histamine-induced increase in IPs formation to the control level. Furthermore, bilastine suppressed basal H1R gene expression in a dose-dependent manner. Data suggest that bilastine is an inverse agonist. Preseasonal prophylactic administration with bilastine could down-regulate basal H1R gene expression in the nasal mucosa and ameliorate the nasal symptoms during the peak pollen period.

Identification of pyrogallol from Awa-tea as an anti-allergic compound that suppresses nasal symptoms and IL-9 gene expression

As the expression level of allergic disease sensitive genes are correlated with the severity of allergic symptoms, suppression of these gene expressions could be promising therapeutics. We demonstrated that protein kinase Cδ / heat shock protein 90-mediated H1R gene expression signaling and nuclear factor of activated T-cells (NFAT)-mediated IL-9 gene expression signaling are responsible for the pathogenesis of pollinosis. Treatment with Awa-tea combined with wild grape hot water extract suppressed these signaling and alleviated nasal symptoms in toluene-2,4-diisocyanate (TDI)-sensitized rats. However, the underlying mechanism of its anti-allergic activity is not elucidated yet. Here, we sought to identify an anti-allergic compound from Awa-tea and pyrogallol was identified as an active compound. Pyrogallol strongly suppressed ionomycin-induced up-regulation of IL-9 gene expression in RBL-2H3 cells. Treatment with pyrogallol in combination with epinastine alleviated nasal symptoms and suppressed up-regulation of IL-9 gene expression in TDI-sensitized rats. Pyrogallol itself did not inhibit calcineurin phosphatase activity. However, pyrogallol suppressed ionomycin-induced dephosphorylation and nuclear translocation of NFAT. These data suggest pyrogallol is an anti-allergic compound in Awa-tea and it suppressed NFAT-mediated IL-9 gene expression through the inhibition of dephosphorylation of NFAT. This might be the underlying mechanism of the therapeutic effects of combined therapy of pyrogallol with antihistamine. J. Med. Invest. 67 : 289-297, August, 2020.

Protein kinase C-δ signaling regulates glucagon secretion from pancreatic islets

Accumulating evidence supports the "glucagonocentric hypothesis", in which antecedent α-cell failure and inhibition of glucagon secretion are responsible for diabetes progression. Protein kinase C (PKC) is involved in glucagon secretion from α-cells, although which PKC isozyme is involved and the mechanism underlying this PKC-regulated glucagon secretion remains unknown. Here, the involvement of PKCδ in the onset and progression of diabetes was elucidated. Immunofluorescence studies revealed that PKCδ was expressed and activated in α-cells of STZ-induced diabetic model mice. Phorbol 12-myristate 13-acetate (PMA) stimulation significantly augmented glucagon secretion from isolated islets. Pre-treatment with quercetin and rottlerin, PKCδ signaling inhibitors, significantly suppressed the PMA-induced elevation of glucagon secretion. While Go6976, a Ca²⁺-dependent PKC selective inhibitor did not suppress glucagon secretion. Quercetin suppressed PMA-induced phosphorylation of Tyr³¹¹ of PKCδ in isolated islets. However, quercetin itself had no effect on either glucagon secretion or glucagon mRNA expression. Our data suggest that PKCδ signaling inhibitors suppressed glucagon secretion. Elucidation of detailed signaling pathways causing PKCδ activation in the onset and progression of diabetes followed by the augmentation of glucagon secretion could lead to the identification of novel therapeutic target molecules and the development of novel therapeutic drugs for diabetes. J. Med. Invest. 64: 122-128, February, 2017.

Histamine H1 Receptor Gene Expression and Drug Action of Antihistamines

The upregulation mechanism of histamine H₁ receptor through the activation of protein kinase C-δ (PKCδ) and the receptor gene expression was discovered. Levels of histamine H₁ receptor mRNA and IL-4 mRNA in nasal mucosa were elevated by the provocation of nasal hypersensitivity model rats. Pretreatment with antihistamines suppressed the elevation of mRNA levels. Scores of nasal symptoms were correlatively alleviated to the suppression level of mRNAs above. A correlation between scores of nasal symptoms and levels of histamine H₁ receptor mRNA in the nasal mucosa was observed in patients with pollinosis. Both scores of nasal symptoms and the level of histamine H₁ receptor mRNA were improved by prophylactic treatment of antihistamines. Similar to the antihistamines, pretreatment with antiallergic natural medicines showed alleviation of nasal symptoms with correlative suppression of gene expression in nasal hypersensitivity model rats through the suppression of PKCδ. Similar effects of antihistamines and antiallergic natural medicines support that histamine H₁ receptor-mediated activation of histamine H₁ receptor gene expression is an important signaling pathway for the symptoms of allergic diseases. Antihistamines with inverse agonist activity showed the suppression of constitutive histamine H₁ receptor gene expression, suggesting the advantage of therapeutic effect.

Y-632 inhibits heat shock protein 90 (Hsp90) function by disrupting the interaction between Hsp90 and Hsp70/Hsp90 organizing protein, and exerts antitumor activity in vitro and in vivo

Heat shock protein 90 (Hsp90) stabilizes a variety of proteins required for cancer cell survival and has been identified as a promising drug target for cancer treatment. To date, several Hsp90 inhibitors have entered into clinical trials, but none has been approved for cancer therapy yet. Thus, exploring new Hsp90 inhibitors with novel mechanisms of action is urgent. In the present study, we show that Y-632, a novel pyrimidine derivative, inhibited Hsp90 in a different way from the conventional Hsp90 inhibitor geldanamycin. Y-632 induced degradation of diverse Hsp90 client proteins through the ubiquitin-proteasome pathway, as geldanamycin did; however, it neither directly bound to Hsp90 nor inhibited Hsp90 ATPase activity. Y-632 inhibited Hsp90 function mainly through inducing intracellular thiol oxidation, which led to disruption of the Hsp90-Hsp70/Hsp90 organizing protein complex and further induced cell adhesion inhibition, G0 /G1 cell cycle arrest, and apoptosis. Moreover, Y-632 efficiently overcame imatinib resistance mediated by Bcr-Abl point mutations both in vitro and in vivo. We believe that Y-632, acting as a novel small-molecule inhibitor of the Hsp90-Hsp70/Hsp90 organizing protein complex, has great potential to be a promising Hsp90 inhibitor for cancer therapy, such as for imatinib-resistant leukemia.