Transient receptor potential vanilloid 4 mediates sour taste sensing via type III taste cell differentiation.

Taste buds are comprised of taste cells, which are classified into types I to IV. Transient receptor potential (TRP) channels play a significant role in taste perception. TRP vanilloid 4 (TRPV4) is a non-selective cation channel that responds to mechanical, thermal, and chemical stimuli. The present study aimed to define the function and expression of TRPV4 in taste buds using Trpv4-deficient mice. In circumvallate papillae, TRPV4 colocalized with a type IV cell and epithelial cell marker but not type I, II, or III markers. Behavioural studies showed that Trpv4 deficiency reduced sensitivity to sourness but not to sweet, umami, salty, and bitter tastes. Trpv4 deficiency significantly reduced the expression of type III cells compared with that in wild type (WT) mice in vivo and in taste bud organoid experiments. Trpv4 deficiency also significantly reduced Ki67-positive cells and ß-catenin expression compared with those in WT circumvallate papillae. Together, the present results suggest that TRPV4 contributes to sour taste sensing by regulating type III taste cell differentiation in mice.

Metabolic engineering using iterative self-cloning to improve lipid productivity in Coccomyxa.

We previously developed a self-cloning system that introduces cDNA of the uridine monophosphate synthase gene (cUMPS) of Coccomyxa sp. strain Obi as a selectable marker into uracil-auxotrophic mutants (Ura-) of the same alga. Here, we developed a Cre/loxP-based system for the removal of cUMPS flanked by directly repeated loxP sites from the Coccomyxa genome using the intracellular delivery of purified Cre recombinase to generate an Ura- strain that was used as a host for second-round transformation using cUMPS as the selection marker. Employing this marker-gene-recycling system, Coccomyxa strains devoid of foreign DNA except the 34-bp loxP sequence, which overexpressed an acyl-(acyl-carrier-protein) thioesterase gene, and a type-2 diacylglycerol acyltransferase gene, were constructed by the sequential introduction of two expression cassettes for the respective genes. One of the resulting strains showed 1.4-fold higher lipid productivity than the wild-type strain. This method will be applicable to other eukaryotic microalgae to create marker-free transgenic strains.

Role of transient receptor potential melastatin 2 in surgical inflammation and dysmotility in a mouse model of postoperative ileus.

In this study, we investigated the role of transient receptor potential melastatin 2 (TRPM2), a nonselective cation channel abundantly expressed in inflammatory cells such as macrophages, in the development of postoperative ileus, a complication of abdominal surgery characterized by gastrointestinal dysmotility. In wild-type mice, we found that intestinal manipulation, a maneuver that elicits symptoms typical of postoperative ileus, delays the transit of fluorescein-labeled dextran, promotes the infiltration of CD68+ macrophages, Ly6B.2+ neutrophils, and MPO+ cells into intestinal muscles, boosts expression of IL-1ß, IL-6, TNF-α, iNOS, and CXCL2 in intestinal muscles and peritoneal macrophages, enhances phosphorylation of ERK and p38 MAPK in intestinal muscles, and amplifies IL-1ß, IL-6, TNF-α, iNOS, and CXCL2 expression in resident and thioglycolate-elicited peritoneal macrophages following exposure to lipopolysaccharide. Remarkably, TRPM2 deficiency completely blocks or diminishes these effects. Indeed, intestinal manipulation appears to activate TRPM2 in resident muscularis macrophages and elicits release of inflammatory cytokines and chemokines, which, in turn, promote infiltration of macrophages and neutrophils into the muscle, ultimately resulting in dysmotility. NEW & NOTEWORTHY Activation of transient receptor potential melastatin 2 (TRPM2) releases inflammatory cytokines and chemokines, which, in turn, promote the infiltration of inflammatory cells and macrophages into intestinal muscles, ultimately resulting in dysmotility. Thus TRPM2 is a promising target in treating dysmotility due to postoperative ileus, a complication of abdominal surgery.

Transient receptor potential vanilloid 1 and transient receptor potential ankyrin 1 contribute to the progression of colonic inflammation in dextran sulfate sodium-induced colitis in mice: Links to calcitonin gene-related peptide and substance P.

Transient receptor potential (TRP) vanilloid 1 (TRPV1) and TRP ankyrin 1 (TRPA1), which are non-selective cation channels, play important roles in the sensation of pain. This study investigated the roles of TRPV1 and TRPA1 in dextran sulfate sodium (DSS)-induced murine colitis. DSS (2%) administered for 7 days caused severe colitis that was significantly less severe in TRPV1-deficient (TRPV1KO) and TRPA1-deficient (TRPA1KO) mice than that in wild-type (WT) mice. Similar colitis attenuations were observed in TRPV1KO and TRPA1KO mice but not in WT mice that had been transplanted with bone marrow cells from WT, TRPA1KO, or TRPV1KO mice. DSS treatment upregulated calcitonin gene-relative peptide (CGRP)- and substance P (SP)-positive nerve fibers in the colonic mucosa of WT mice. TRPV1KO and TRPA1KO mice showed significant reductions in the DSS-induced upregulation of SP, but the DSS-induced upregulation of CGRP was not reduced. Sensory deafferentation evoked by pretreatment with high doses of capsaicin markedly exacerbated DSS-induced colitis with reductions in DSS-induced upregulation of SP- and CGRP-positive nerve fibers. These findings suggest that neuronal TRPV1 and TRPA1 contribute to the progression of colonic inflammation. While these responses may be mediated by the upregulation of SP-mediated deleterious mechanisms, CGRP may be associated with protective mechanisms.

Transient receptor potential vanilloid 4 channel regulates vascular endothelial permeability during colonic inflammation in dextran sulphate sodium-induced murine colitis.

BACKGROUND AND PURPOSE: The transient receptor potential vanilloid 4 (TRPV4) channel is a non-selective cation channel involved in physical sensing in various tissue types. The present study aimed to elucidate the function and expression of TRPV4 channels in colonic vascular endothelial cells during dextran sulphate sodium (DSS)-induced colitis. EXPERIMENTAL APPROACH: The role of TRPV4 channels in the progression of colonic inflammation was examined in a murine DSS-induced colitis model using immunohistochemical analysis, Western blotting and Evans blue dye extrusion assay. KEY RESULTS: DSS-induced colitis was significantly attenuated in TRPV4-deficient (TRPV4 KO) as compared to wild-type mice. Repeated intrarectal administration of GSK1016790A, a TRPV4 agonist, exacerbated the severity of DSS-induced colitis. Bone marrow transfer experiments demonstrated the important role of TRPV4 in non-haematopoietic cells for DSS-induced colitis. DSS treatment up-regulated TRPV4 expression in the vascular endothelia of colonic mucosa and submucosa. DSS treatment increased vascular permeability, which was abolished in TRPV4 KO mice. This DSS-induced increase in vascular permeability was further enhanced by i.v. administration of GSK1016790A, and this effect was abolished by the TRPV4 antagonist RN1734. TRPV4 was co-localized with vascular endothelial (VE)-cadherin, and VE-cadherin expression was decreased by repeated i.v. administration of GSK1016790A during colitis. Furthermore, GSK106790A decreased VE-cadherin expression in mouse aortic endothelial cells exposed to TNF-α. CONCLUSION AND IMPLICATIONS: These findings indicate that an up-regulation of TRPV4 channels in vascular endothelial cells contributes to the progression of colonic inflammation by increasing vascular permeability. Thus, TRPV4 is an attractive target for the treatment of inflammatory bowel diseases.

G protein-coupled receptor 35 contributes to mucosal repair in mice via migration of colonic epithelial cells.

G protein-coupled receptor 35 (GPR35), a receptor for lysophosphatidic acid, is highly expressed in the gastrointestinal tract. Recently, GPR35 has been implicated in the onset of inflammatory bowel disease (IBD), but its role in physiological and pathological processes in the colon remains undefined. In this study, we investigated the contribution of GPR35-mediated signalling to mucosal repair of colonic epithelium in IBD. GPR35 function was examined in a wound healing model, using young adult mouse colon epithelium (YAMC) cells, and in a dextran sulphate sodium (DSS)-induced mouse model of colitis. Cell proliferation, mRNA expression, extracellular signal-regulated kinase (ERK) activation, and protein localization were determined by MTT assay, quantitative RT-PCR, western blotting, and immunohistochemistry, respectively. GPR35 agonists (YE120, zaprinast, and pamoic acid) promoted wound repair in a concentration-dependent manner independently of cell proliferation, whereas a specific GPR35 antagonist CID2745687, forskolin, and pertussis toxin reversed the YE120-induced effect. YE120 increased the mRNA expression of fibronectin and its receptor integrin α5, and ERK1/2 phosphorylation, but these responses were attenuated by CID2745687 and forskolin. Furthermore, the severity of DSS-induced colitis was significantly reduced by daily injections of pamoic acid via upregulation of fibronectin and integrin α5 in the colonic epithelium. GPR35 signalling promotes mucosal repair by inducing fibronectin and integrin α5 expression, coupling to Gi protein, and activating ERK1/2 in colonic epithelial cells. These findings define GPR35 as a candidate therapeutic target in IBD.

Voltage controlled interfacial magnetism through platinum orbits.

Electric fields at interfaces exhibit useful phenomena, such as switching functions in transistors, through electron accumulations and/or electric dipole inductions. We find one potentially unique situation in a metal-dielectric interface in which the electric field is atomically inhomogeneous because of the strong electrostatic screening effect in metals. Such electric fields enable us to access electric quadrupoles of the electron shell. Here we show, by synchrotron X-ray absorption spectroscopy, electric field induction of magnetic dipole moments in a platinum monatomic layer placed on ferromagnetic iron. Our theoretical analysis indicates that electric quadrupole induction produces magnetic dipole moments and provides a large magnetic anisotropy change. In contrast with the inability of current designs to offer ultrahigh-density memory devices using electric-field-induced spin control, our findings enable a material design showing more than ten times larger anisotropy energy change for such a use and highlight a path in electric-field control of condensed matter.

NOX1/NADPH Oxidase Expressed in Colonic Macrophages Contributes to the Pathogenesis of Colonic Inflammation in Trinitrobenzene Sulfonic Acid-Induced Murine Colitis.

NOX1/NADPH oxidase, a nonphagocytic isoform of reactive oxygen species-producing enzymes, is highly expressed in the colon, but the physiologic and pathophysiologic roles of this isoform are not fully understood. The present study investigated the role of NOX1 in the development of colonic inflammation in a trinitrobenzene sulfonic acid (TNBS)-induced murine colitis model. Intrarectal injection of TNBS caused severe colitis accompanied by body weight loss, diarrhea, and increased myeloperoxidase (MPO) activity in wild-type (WT) mice. In contrast, the severity of colitis was significantly attenuated in NOX1-deficient (NOX1KO) mice (the inhibitions of macroscopic damage score, body weight loss, diarrhea score, and MPO activity were 73.1%, 36.8%, 83.3%, and 98.4%, respectively). TNBS-induced upregulation of inflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-1ß), chemokines (CXCL1 and CXLC2), and inducible nitric oxide synthase (iNOS) was also significantly less in NOX1KO than in WT mice (the inhibitions were 100.8%, 89.0%, 63.5%, 96.7%, and 97.1%, respectively). Expression of NOX1 mRNA was detected not only in the lamina propria but also in peritoneal macrophages isolated from WT mice. Increased expression of TNF-α, IL-1ß, and iNOS in peritoneal macrophages exposed to lipopolysaccharide was significantly attenuated in macrophages isolated from NOX1KO mice (68.1%, 67.0%, and 79.3% inhibition, respectively). These findings suggest that NOX1/NADPH oxidase plays an important role in the pathogenesis of TNBS-induced colonic inflammation via upregulation of inflammatory cytokines, chemokines, and iNOS. NOX1 in colonic macrophages may become a potential target in pharmacologic intervention for inflammatory bowel disease.

Tumor necrosis factor α decreases glucagon-like peptide-2 expression by up-regulating G-protein-coupled receptor 120 in Crohn disease.

Glucagon-like peptide (GLP)-2, secreted by L cells in the small intestine, has anti-inflammatory effects in the gastrointestinal tract. A GLP-2 analogue has been an effective treatment for Crohn disease (CD). G-protein-coupled receptor (GPR) 40 and GPR120 are probably involved in GLP-2 production, the mechanisms of which remain unclear. In our experiments, normal ileal mucosa expressed GPR40, but rarely expressed GPR120. However, both GPRs were overexpressed in the L cells of the inflamed ileal mucosa of CD patients. Mucosal inflammation induced the overexpression of GPR40, GPR120, and several inflammatory cytokines, with correlations between ileal concentrations of tumor necrosis factor (TNF)-α and GPR expression levels; however, inflammation did not induce the expression of proglucagon, a precursor of GLP-2 in CD patients. In rat L cells and GLUTag cells, TNF-α treatment increased GPR120 mRNA expression without affecting GPR40 mRNA expression. Dual agonists of GPR40 and GPR120, GW9508 and linoleic acid, respectively, increased GLP-2 production from L cells, but these agonists decreased it in the presence of TNF-α. The GPR40 antagonist, GW1100, inhibited the GW9508-induced increase in GLP-2 production, and silencing GPR120 resulted in further elevation of GLP-2 production. Thus, GPR120-dependent signaling inhibited the stimulatory effects of GPR40 on GLP-2 expression, and TNF-α treatment decreased GLP-2 expression by up-regulating GPR120 expression in L cells.

Acid reflux directly causes sleep disturbances in rat with chronic esophagitis.

BACKGROUND & AIMS: Gastroesophageal reflux disease (GERD) is strongly associated with sleep disturbances. Proton pump inhibitor (PPI) therapy improves subjective but not objective sleep parameters in patients with GERD. This study aimed to investigate the association between GERD and sleep, and the effect of PPI on sleep by using a rat model of chronic acid reflux esophagitis. METHODS: Acid reflux esophagitis was induced by ligating the transitional region between the forestomach and the glandular portion and then wrapping the duodenum near the pylorus. Rats underwent surgery for implantation of electrodes for electroencephalogram and electromyogram recordings, and they were transferred to a soundproof recording chamber. Polygraphic recordings were scored by using 10-s epochs for wake, rapid eye movement sleep, and non-rapid eye movement (NREM) sleep. To examine the role of acid reflux, rats were subcutaneously administered a PPI, omeprazole, at a dose of 20 mg/kg once daily. RESULTS: Rats with reflux esophagitis presented with several erosions, ulcers, and mucosal thickening with basal hyperplasia and marked inflammatory infiltration. The reflux esophagitis group showed a 34.0% increase in wake (232.2±11.4 min and 173.3±7.4 min in the reflux esophagitis and control groups, respectively; p<0.01) accompanied by a reduction in NREM sleep during light period, an increase in sleep fragmentation, and more frequent stage transitions. The use of omeprazole significantly improved sleep disturbances caused by reflux esophagitis, and this effect was not observed when the PPI was withdrawn. CONCLUSIONS: Acid reflux directly causes sleep disturbances in rats with chronic esophagitis.