Yuki Kai

Distribution of aquaporin genes and selection of individual reference genes for quantitative real-time RT-PCR analysis in multiple tissues of the mouse

Aquaporins (AQPs) are a family of water-transporting proteins that are selectively expressed in epithelial, endothelial, and many other cell types of various tissues, where they play important physiological functions. However, the accurate distribution of AQP gene expression has not yet been examined in various tissues of the mouse. We first evaluated the tissue distribution of AQP gene expression using tongue, nasal epithelium, bronchus, trachea, lung, esophagus, stomach, ileum, transverse colon, liver, pancreas, whole blood, thigh muscle, spinal cord, brain, thoracic aorta, heart, kidney, thymus, spleen, skin, eye, and testis of the mouse. Furthermore, for a quantitative analysis, we selected appropriate reference genes for normalized qRT-PCR data in various tissues. The stability of the reference genes was assessed using NormFinder. The stably expressed genes identified in the present study were 18s rRNA. When 18s rRNA was used, as the best reference gene in the present study, the genes for AQPs 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, and 12 were notably expressed in the eye, lung, testis, eye, spinal cord, trachea, kidney, testis, testis, testis, testis, and pancreas. These results, regarding the distribution of AQPs, suggest that AQPs may be involved in various physiological and pathophysiological processes.

Curcumin Inhibits 5‐Fluorouracil‐induced Up‐regulation of CXCL1 and CXCL2 of the Colon Associated with Attenuation of Diarrhoea Development

The compound 5‐fluorouracil (5‐FU) is used in cancer chemotherapy and is known to cause diarrhoea. We recently reported that chemokine (C‐X‐C motif) ligand 1 (CXCL1) and neutrophils in the colonic mucosa were markedly increased by the administration of 5‐FU in mice. Curcumin has anti‐inflammatory, antitumour and antioxidant properties. Therefore, we examined the effect of curcumin on 5‐FU‐induced diarrhoea development and CXCL1 and CXCL2 up‐regulation in the colon. Mice were given 5‐FU (50 mg/kg, i.p.) daily for 4 days. Curcumin (100 or 300 mg/kg, p.o.) was administered on the day before the first administration of 5‐FU and administered 30 min. before the administration of 5‐FU. Gene expression levels of CXCL1 and CXCL2 in the colon were examined by real‐time RT‐PCR. Curcumin reduced the 5‐FU‐induced diarrhoea development. Under this condition, the CXCL1 and CXCL2 gene up‐regulated by 5‐FU administration was inhibited by curcumin. The gene expression of CXCL1 and CXCL2 was also enhanced by 5‐FU application in vitro. The 5‐FU‐induced up‐regulated CXCL1 and CXCL2 gene expressions were inhibited by curcumin, Bay‐117082 and bortezomib, nuclear factor kappa B (NF‐κB) inhibitors, C646, a p300/cyclic adenosine monophosphate response element‐binding protein–histone acetyltransferase (HAT) inhibitor. In conclusion, these findings suggested that curcumin prevented the development of diarrhoea by inhibiting NF‐κB and HAT activation.

Denatonium and 6-n-Propyl-2-thiouracil, Agonists of Bitter Taste Receptor, Inhibit Contraction of Various Types of Smooth Muscles in the Rat and Mouse.

Recently the global expression of taste 2 receptors (TAS2Rs) on smooth muscle cells in human airways was demonstrated. Here, the effects of agonists of taste receptor, type 2, denatonium and 6-n-propyl-2-thiouracil, on smooth-muscle contraction were examined in the rat and mouse. Contractions induced by carbachol (CCh), high K(+), and sodium fluoride, but not calyculin-A, were inhibited significantly in the presence of a TAS2R agonist in the bronchial smooth muscle of mice. The contraction induced by CCh was inhibited by TAS2R agonists in ileal smooth muscle. Phenylephrine-induced contraction was also inhibited by TAS2R agonists in aortic smooth muscle. Gastrointestinal motility and blood pressure were attenuated by administration of TAS2R agonists in vivo. These findings suggest that TAS2R may be receptor for endogenous biologically active substances as well as for bitter tastes on the tongue. TAS2R signaling could be employed in the development of anti-asthmatic, anti-spasmodic, and anti-hypertensive drugs.

ELR+ chemokine-mediated neutrophil recruitment is involved in 2,4,6-trinitrochlorobenzene-induced contact hypersensitivity

Contact dermatitis is a form of delayed‐type hypersensitivity characterized by localized thickening, papules, redness and vesicles of the skin. A model of contact dermatitis involving repeated challenge of a hapten is adapted to assess dermatitis as characterized by skin thickening. Recently, it was reported that neutrophils have crucial roles in contact hypersensitivity. We thus examined the involvement of CXC chemokines bearing the glutamic acid–leucine–arginine (ELR) motif (“ELR+ chemokines”) and neutrophils in the ear swelling induced by 2,4,6‐trinitrochlorobenzene (TNCB) challenges in the present study. Mice were sensitized by application of TNCB on their abdominal skin. They were then challenged thrice with TNCB to the ear. The CXCR2 antagonist SB225002 (9 mg/kg, i.p.) was administered before each TNCB challenge. Gene expressions and protein levels of the ELR+ chemokines CXCL1, 2 and 5 was increased markedly in mouse ear after the final TNCB challenge. In addition, we indicated that gene expression of CXCL1 was enhanced in the epidermis and dermis upon TNCB challenge. Expression of the CXCL2 gene was enhanced in the epidermis, and that of the CXCL5 gene was enhanced in the dermis. The swelling induced by TNCB challenges was significantly attenuated by SB225002. Furthermore, the increases in myeloperoxidase activity, and expression of myeloperoxidase and neutrophil elastase induced by TNCB challenge in mouse ear were inhibited by SB225002. These data suggest that ear swelling resulting from TNCB challenges might be concerned by upregulated ELR+ chemokine‐induced neutrophil recruitment.

Mechanisms underlying the pathogenesis of hyper-contractility of bronchial smooth muscle in allergic asthma

Airway hyperresponsiveness (AHR) and inflammation are key pathophysiological features of asthma. Enhanced contraction of bronchial smooth muscle (BSM) is one of the causes of the AHR. It is thus important for development of asthma therapy to understand the change in the contractile signaling of airway smooth muscle cells associated with the AHR. In addition to the Ca2+-mediated phosphorylation of myosin light chain (MLC), contractile agonists also enhance MLC phosphorylation level, Ca2+-independently, by inactivating MLC phosphatase (MLCP), called Ca2+ sensitization of contraction, in smooth muscle cells including airways. To date, involvements of RhoA/ROCKs and PKC/Ppp1r14a (also called as CPI-17) pathways in the Ca2+ sensitization have been identified. Our previous studies revealed that the agonist-induced Ca2+ sensitization of contraction is markedly augmented in BSMs of animal models of allergen-induced AHR. In BSMs of these animal models, the expression of RhoA and CPI-17 proteins were significantly increased, indicating that both the Ca2+ sensitizing pathways are augmented. Interestingly, incubation of BSM cells with asthma-associated cytokines, such as interleukin-13 (IL-13), IL-17, and tumor necrosis factor-α (TNF-α), caused up-regulations of RhoA and CPI-17 in BSM cells of naive animals and cultured human BSM cells. In addition to the transcription factors such as STAT6 and NF-κB activated by these inflammatory cytokines, an involvement of down-regulation of miR-133a, a microRNA that negatively regulates RhoA translation, has also been suggested in the IL-13- and IL-17-induced up-regulation of RhoA. Thus, the Ca2+ sensitizing pathways and the cytokine-mediated signaling including microRNAs in BSMs might be potential targets for treatment of allergic asthma, especially the AHR.

Role of peptide YY in 5-fluorouracil-induced reduction of dietary intake.

5‐fluorouracil (5‐FU) is part of the standard care for cancer treatment but is associated with high incidences of appetite loss and reduced food intake, which may contribute to chemotherapy‐induced cachexia (weakness and wasting of tissue). The role of gastrointestinal satiety hormones in chemotherapy‐induced appetite loss has not been intensively investigated. Peptide YY (PYY) and glucagon‐like peptide (GLP)‐1 are important signals of gastrointestinal satiety, so this study examined the roles of these gut hormones in 5‐FU‐induced reduction of dietary intake. Mice were given 5‐FU (50 mg/kg, intraperitoneal [i.p.]) every day for 4 consecutive days. Gene expression levels of proglucagon (Pro‐Gcg), a precursor of GLP‐1, and PYY in the colon were examined by real‐time RT‐PCR. Serum levels of GLP‐1 and PYY were measured by enzyme‐linked immunosorbent assay. Some mice were pretreated with the GLP‐1 receptor antagonist exendin9–39 (1 mg/kg) or the neuropeptide Y type 2 (NPY2) receptor antagonist BIIE0246 (2 mg/kg) via the i.p. route 30 minutes before 5‐FU administration. Mice receiving 5‐FU exhibited a significant reduction in food intake that was correlated with body weight loss. These mice also showed significantly enhanced expression levels of mRNAs encoding pro‐GLP‐1 and PYY in the transverse and distal colon as well as elevated serum concentrations of GLP‐1 and PYY compared to vehicle‐treated controls. The 5‐FU‐induced reduction in food intake was attenuated by BIIE0246 but not by exendin9–39. These data suggest that administration of a NPY2 receptor antagonist may be effective for attenuating the anorexia caused by 5‐FU chemotherapy.

Rac1 modulates G-protein-coupled receptor-induced bronchial smooth muscle contraction

Abstract Increasing evidence suggests a functional role of RhoA/Rho‐kinase signalling as a mechanism for smooth muscle contraction; however, little is known regarding the roles of Rac1 and other members of the Rho protein family. This study aimed to examine whether Rac1 modulates bronchial smooth muscle contraction. Ring preparations of bronchi isolated from rats were suspended in an organ bath, and isometric contraction of circular smooth muscle was measured. Immunoblotting was used to examine myosin light chain phosphorylation in bronchial smooth muscle. Our results demonstrated that muscle contractions induced by carbachol (CCh) and endothelin‐1 (ET‐1) were inhibited by EHT1864, a selective Rac1 inhibitor, and NSC23766, a selective inhibitor of Rac1‐specific guanine nucleotide exchange factors. Similarly, myosin light chain and myosin phosphatase target subunit 1 (MYPT1) at Thr853 phosphorylation induced by contractile agonist were inhibited with Rac1 inhibition. However, contractions induced by high K+, calyculin A (a potent protein phosphatase inhibitor) and K+/PDBu were not inhibited by these Rac1 inhibitors. Interestingly, NaF (a G‐protein activator)‐induced contractions were inhibited by EHT1864 but not by NSC23766. We next examined the effects of a trans‐acting activator of transcription protein transduction domain (PTD) fusion protein with Rac1 (PTD‐Rac1) on muscle contraction. The constitutively active form of PTD‐Rac1 directly induced force development and contractions were abolished by EHT1864. These results suggest that Rac1, activated by G protein‐coupled receptor agonists, such as CCh and ET‐1, may induce myosin light chain and MYPT phosphorylation and modulate the contraction of bronchial smooth muscle.

Dexamethasone exacerbates cisplatin-induced muscle atrophy

Dexamethasone for antiemetic therapy is typically administered with anticancer drugs such as cisplatin. We previously reported that cisplatin upregulates the muscle‐specific E3 ubiquitin ligase genes, namely muscle ring‐finger protein 1 (MuRF1) and atrophy gene‐1 (atrogin‐1), and promotes muscle atrophy in mice. It is well known that dexamethasone causes upregulation of MuRF1 and Atrogin‐1 expression in skeletal muscles. Although it is speculated that a combination of dexamethasone and cisplatin worsens muscle atrophy, there are no reports based on research. We thereby investigated the effects of cisplatin and dexamethasone, alone or in combination, on the expression of MuRF1 and Atrogin‐1 in murine skeletal muscles and C2C12 myotubes. Mice were intraperitoneally injected with cisplatin or the vehicle control once daily for 4 days. Dexamethasone or the vehicle control was subcutaneously administered 30 minutes prior to the administration of cisplatin. Dexamethasone enhanced MuRF1 and Atrogin‐1 gene expression upregulated by cisplatin in murine quadriceps muscles and C2C12 myotubes. Cisplatin‐caused upregulation of myostatin and downregulation of IGF‐1 gene expression were also enhanced by co‐administration of dexamethasone in murine quadriceps muscles and C2C12 myotubes. This study shows that the combination treatment of cisplatin and dexamethasone exacerbated muscle atrophy in mice. Therefore, this treatment regimen might exacerbate muscle atrophy in cancer patients.

Active Ingredients of Hange-shashin-to, Baicalelin and 6-Gingerol, Inhibit 5-Fluorouracil-Induced Upregulation of CXCL1 in the Colon to Attenuate Diarrhea Development

5-Fluorouracil (5-FU) is widely used as an anti cancer drug and is known to cause severe diarrhea. Recently we suggested that levels of chemokine (C-X-C motif) ligand 1 (CXCL1) and neutrophil recruitment in the colonic mucosa were drastically increased by the 5-FU administration in mice. Hange-shashin-to (HST) is prescribed in Japan for treat gastritis, stomatitis, and inflammatory diarrhea. We therefore examined the effects of HST and its active ingredients on 5-FU-induced CXCL1 upregulation in cultured colon tissue, and also examined the effects of HST on 5-FU-induced diarrhea development in the mouse. The distal colon isolated from the mouse was incubated with 5-FU and HST. Mice were given 5-FU (50 mg/kg, intraperitoneally (i.p.)) daily for four days. HST (300 mg/kg, per os (p.o.)) was administered 30 min before mice received 5-FU. mRNA levels of CXCL1 in the colon were examined using quantitative RT-PCR. 5-FU enhanced CXCL1 mRNA in the colon but the effect by 5-FU was markedly suppressed by application of HST and its active ingredients, baicalein and 6-gingerol. Nuclear factor kappa B (NF-κB) was activated by 5-FU treatment in cultured colon tissue, which was also suppressed by HST and the combination of baicalein and 6-gingerol. Furthermore, HST reduced 5-FU-induced diarrhea development. Under such experimental condition, CXCL1 gene, protein levels of neutrophil elastase and myeloperoxidase upregulation induced by 5-FU in the colon was attenuated by HST. These findings suggest that HST, especially baicalein and 6-gingerol, prevent the development of neutrophil recruitment and diarrhea by the inhibition of NF-κB activity.