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Lysophosphatidic acid (LPA) exerts a variety of biological responses through specific receptors: three subtypes of the EDG-family receptors, LPA1, LPA2, and LPA3 (formerly known as EDG-2, EDG-4, and EDG-7, respectively), and LPA4/GPR23, structurally distinct from the EDG-family receptors, have so far been identified. In the present study, we characterized(More)
T cell death-associated gene 8 (TDAG8) has been reported to be a receptor for psychosine. Ovarian cancer G-protein-coupled receptor 1 (OGR1) and GPR4, G-protein-coupled receptors (GPCRs) closely related to TDAG8, however, have recently been identified as proton-sensing or extracellular pH-responsive GPCRs that stimulate inositol phosphate and cAMP(More)
Extracellular acidification inhibited LPS-induced TNF-alpha protein production, which was associated with an inhibition of TNF-alpha mRNA expression, in mouse peritoneal macrophages. The LPS-induced cytokine production was also inhibited by G(s) protein-coupled receptor agonists prostaglandin E(1) and isoproterenol. Among OGR1 family proton-sensing(More)
Extracellular acidification inhibited formyl-Met-Leu-Phe- or C5a-induced superoxide anion (O(2)(-)) production in differentiated HL-60 neutrophil-like cells and human neutrophils. A cAMP-increasing agonist, prostaglandin E(1), also inhibited the formyl peptide-induced O(2)(-) production. The inhibitory action on the O(2)(-) production by extracellular(More)
GPR4 was initially identified as a receptor for sphingosylphosphorylcholine and lysophosphatidylcholine; however, lipid actions have not always been confirmed. Instead, ligand-independent actions have sometimes been observed in GPR4- and other OGR1 family receptor-expressing cells. Here, we examined the possible involvement of extracellular protons, which(More)
Dexamethasone (DEX), a potent glucocorticoid, increased the expression of T-cell death associated gene 8 (TDAG8), a proton-sensing G protein-coupled receptor, which is associated with the enhancement of acidic pH-induced cAMP accumulation, in peritoneal macrophages. We explored the role of increased TDAG8 expression in the anti-inflammatory actions of DEX.(More)
Interleukin-1β (IL-1β) is released from activated microglia and involved in the neurodegeneration of acute and chronic brain disorders, such as stroke and Alzheimer's disease, in which extracellular acidification has been shown to occur. Here, we examined the extracellular acidic pH regulation of IL-1β production, especially focusing on TDAG8, a major(More)
G protein-coupled receptor 4 (GPR4), previously proposed as the receptor for sphingosylphosphorylcholine, has recently been identified as the proton-sensing G protein-coupled receptor (GPCR) coupling to multiple intracellular signaling pathways, including the Gs protein/cAMP and G13 protein/Rho. In the present study, we characterized some imidazopyridine(More)
We assessed achromatic luminance and isoluminant chromatic contrast sensitivity functions of a 20-year-old male. He showed severe motor and intellectual disabilities after advanced adrenoleukodystrophy, which started at the age of 7. Optokinetic nystagmus (OKN) to drifting gratings was used to assess his contrast sensitivities. Although the achromatic(More)