Explore the vast range of titles available.

\"This state-of-the-art reference addresses lysophospholipids, a special kind of fat that has been found to have a growing number of receptors within the cell and that has important, natural roles in the body, being essential for normal reproduction, development, maturation and life. This book covers the biochemistry, interactions, and signaling of lysophospholipids as well as its potential for producing new therapies for a range of medically important human diseases. Bringing together current knowledge in lysophospholipid signaling, this represents a must-have book for all academic, industrial, and medical school and hospital libraries\"--Provided by publisher.

Type 1 innate lymphoid cells (ILC1s) are a class of tissue-resident cells with antitumor activity, suggesting its possible role in solid tumor immune surveillance, but it is not clear whether manipulating ILC1s can induce potent antitumor immune responses. Here, we found that G-protein-coupled receptor 34 (GPR34), a receptor for lysophosphatidylserine (LysoPS), was highly expressed on ILC1s but not on conventional natural killer cells in the tumor microenvironment. LysoPS was enriched in the tumor microenvironment and could inhibit ILC1 activation via GPR34. Genetic deletion of LysoPS synthase Abhd16a expression in tumors or Gpr34 expression in ILC1s or antagonizing GPR34 enhanced ILC1 antitumor activity. In individuals with cancer, ABHD16A expression in tumors or GPR34 expression in ILC1s was inversely correlated with the antitumor activity of ILC1s or ILC1-like cells. Thus, our results demonstrate that manipulating ILC1s can induce potent antitumor immunity, and GPR34 is a metabolic immune checkpoint that can be targeted to develop ILC1-based immunotherapy. Zhou and colleagues find that GPR34 is a metabolic immune checkpoint for ILC1-mediated antitumor immunity.

Background Neuropathic pain is caused by sensory nerve injury, but effective treatments are currently lacking. Microglia are activated in the spinal dorsal horn after sensory nerve injury and contribute to neuropathic pain. Accordingly, molecules expressed by these cells are considered potential targets for therapeutic strategies. Our previous gene screening study using a mouse model of motor nerve injury showed that the G-protein-coupled receptor 34 gene (GPR34) is induced by nerve injury. Because GPR34 is now considered a microglia-enriched gene, we explored the possibility that it might be involved in microglial activation in the dorsal horn in a mouse model of neuropathic pain. Methods mRNA expression of GPR34 and pro-inflammatory molecules was determined by quantitative real-time PCR in wild-type and GPR34-deficient mice with L4 spinal nerve injury. In situ hybridization was used to identify GPR34 expression in microglia, and immunohistochemistry with the microglial marker Iba1 was performed to examine microglial numbers and morphology. Mechanical sensitivity was evaluated by the von Frey hair test. Liquid chromatography–tandem mass spectrometry quantified expression of the ligand for GPR34, lysophosphatidylserine (LysoPS), in the dorsal horn, and a GPR34 antagonist was intrathecally administrated to examine the effect of inhibiting LysoPS-GPR34 signaling on mechanical sensitivity. Results GPR34 was predominantly expressed by microglia in the dorsal horn after L4 nerve injury. There were no histological differences in microglial numbers or morphology between WT and GPR34-deficient mice. However, nerve injury-induced pro-inflammatory cytokine expression levels in microglia and pain behaviors were significantly attenuated in GPR34-deficient mice. Furthermore, the intrathecal administration of the GPR34 antagonist reduced neuropathic pain. Conclusions Inhibition of GPR34-mediated signal by GPR34 gene deletion reduced nerve injury-induced neuropathic pain by suppressing pro-inflammatory responses of microglia without affecting their morphology. Therefore, the suppression of GPR34 activity may have therapeutic potential for alleviating neuropathic pain.

Lysophosphatidylserine (LysoPS) is a naturally occurring lipid mediator involved in various physiological and pathological processes especially those related to the immune system. GPR34, GPR174, and P2Y10 have been identified as the receptors for LysoPS, and its analogues have been developed as agonists or antagonists for these receptors. However, the lack of structural information hinders the drug development with novel characteristics, such as nonlipid ligands and allosteric modulators. Here, we determined the structures of human GPR34 and GPR174 in complex with LysoPS and G protein by cryo-EM. Combined with structural analysis and functional studies, we elucidated the lipid-binding modes of these receptors. By structural comparison, we identified the structural features of GPR34 and GPR174 in active state. Taken together, our findings provide insights into ligand recognition and signaling of LysoPS receptors and will facilitate the development of novel therapeutics for related inflammatory diseases and autoimmune diseases.

Sterile neuroinflammation is a major driver of multiple neurological diseases. Myelin debris can act as an inflammatory stimulus to promote inflammation and pathologies, but the mechanism is poorly understood. Here, we showed that lysophosphatidylserine (LysoPS) - GPR34 axis played a critical role in microglia-mediated myelin debris sensing and the subsequent neuroinflammation. Myelin debris-induced microglia activation and proinflammatory cytokine expression relied on its lipid component LysoPS. Both myelin debris and LysoPS promoted microglia activation and the production of proinflammatory cytokines via GPR34 and its downstream PI3K-AKT and ERK signaling. In vivo, reducing the content of LysoPS in myelin or inhibition of GPR34 with genetic or pharmacological approaches reduced neuroinflammation and pathologies in the mouse models of multiple sclerosis and stroke. Thus, our results identify GPR34 as a key receptor to sense demyelination and CNS damage and promote neuroinflammation, and suggest it as a potential therapeutic target for demyelination-associated diseases.

Lysophospholipids have long been recognized as membrane phospholipid metabolites, but only recently has their role as intercellular signaling molecules been appreciated. Two of the best-studied lysophospholipids, LPA and S1P, signal through cognate G-protein-coupled receptors to activate many well-known intracellular signaling pathways, leading to a variety of biologically important cell responses. Lysophospholipids and their receptors have been found in a wide range of tissues and cell types, indicating their importance in many physiological processes, including reproduction, vascular development, cancer and nervous system function. This article will focus on the most recent findings regarding the biological functions of lysophospholipids in mammalian systems, specifically as they relate to health and disease.

Purpose G-protein coupled receptor (GPR 34) has been found to play important roles in some cancers and regulates the proliferation, apoptosis, and migration of these cancer cells. However, the mechanisms underlying how GPR34 functions to regulate growth and proliferation of colorectal cancer cells remains to be clarified. Methods We employed stable GPR34 knockdown LS174T cell models, GPR34 Mab blocking, a CCK-8 kit, and a colony formation assay to characterize the effect of GPR34 on the proliferation of LS174T in vitro and xenograft tumor growth in vivo. The mRNA level of GPR34 was detected by RT-PCR in tumor tissues and adjacent normal tissues from 34 CRC patients. Results Based on RT-PCR results, GPR34 exhibited high level in tumor samples compared with adjacent normal samples. Increased expression of GPR34 is more associated with poor prognosis of CRC as shown in The Cancer Genome Atlas (TCGA) dataset by Kaplan–Meier survival analysis. Furthermore, we showed that GPR34 knockdown inhibited the proliferation of LS174T colon cancer cells and related xenograft tumor growth. Searching for the distinct molecular mechanism, we identified several contributors to proliferation of LS174T colon cancer cells: PI3K subunits/PTEN, PDK1/AKT, and Src/Raf/Ras/ERK. GPR34 knockdown inhibited the proliferation of LS174T cells by upregulating expression of PTEN, and downregulating expression of PI3K subunits p110-beta. Conclusion Our findings provide direct evidence that GPR34 regulates the proliferation of LS174T cells and the growth of LS174T tumor xenografts by regulating different pathways. High expression of GPR34 mRNA could then be used to predict poor prognosis of CRC.

The lysophospholipids, sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA), stimulate chemotaxis and induce differentiation of human keratinocytes. As Ca2+ plays an important role in keratinocyte differentiation, we studied Ca2+ signaling by S1P and LPA in these cells, known to express mRNA transcripts of the S1P1-5 and LPA1-3 receptors, and the receptor subtypes involved in this process. S1P and LPA caused transient increases in intracellular free Ca2+ concentration ([Ca2+]i), with pEC50 values of 8.5±0.11 and 7.5±0.23, respectively. The [Ca2+]i increases are apparently mediated by stimulation of phospholipase C and involve Ca2+ mobilization from thapsigargin-sensitive stores and subsequent Ca2+ influx. The LPA-induced [Ca2+]i increases were not inhibited by the LPA1/3 receptor antagonist, dioctanoylglycerol pyrophosphate. The S1P-induced [Ca2+]i increases were largely inhibited by the putative S1P3 antagonist, BML-241, and the S1P1/3 antagonist, VPC23019. The S1P1-specific agonist, SEW2871, did not increase [Ca2+]i but stimulated chemotaxis of keratinocytes, which was fully blocked by S1P1 antisense oligonucleotides. The data indicate that LPA and S1P potently increase [Ca2+]i in human keratinocytes and that the effect of LPA is mediated by LPA2, whereas that of S1P is mediated at least to a large part by S1P3. The S1P1 receptor, without stimulating [Ca2+]i increases, mediates chemotaxis of keratinocytes.

The phospholipids sphingosine 1-phosphate (S1P) and lysophosphatidic acid (LPA) act via transmembrane receptors S1P 1-5 and LPA 1-3, respectively. Both have been implicated in inflammatory responses. S1P and LPA receptor profiles on neutrophils of patients with pneumonia compared with healthy subjects were determined by PCR and Western blotting. Chemotaxis studies were performed to assess functional differences. S1P or LPA receptors were immunoprecipitated from neutrophils to assess receptor heterodimerization with CXCR1, an IL-8 receptor, by Western blotting. Receptors S1P 1, 4, and 5 and LPA 2 were expressed on neutrophils from both subject groups, but S1P 3 and LPA 1 receptor expression was mainly confined to neutrophils of patients with pneumonia. Chemotaxis of neutrophils from patients with pneumonia compared with control subjects was significantly increased in response to S1P and LPA. Pretreatment with S1P or LPA reduced IL-8-induced neutrophil chemotaxis and transcriptional expression of the CXCR1 receptor. Receptors S1P 3 and 4 and LPA 1 formed constitutive heterodimers with CXCR1. LPA treatment reduced the amount of LPA 1/CXCR1 heterodimer. Therefore, profiles of S1P and LPA receptors differ between neutrophils of patients with pneumonia and control subjects, with consequences for neutrophil function.

Background：Overexpression of G-protein coupled receptor 34 （GPR34） affects the progression and prognosis of human gastric adenocarcinoma,however,the role of GPR34 in gastric cancer development and progression has not been well-determined.The current study aimed to investigate the effect of GPR34 knockdown on the proliferation,migration,and apoptosis of HGC-27 gastric cancer cells and the underlying mechanisms.Methods：The expression of GPR34 in gastric cancer cell line HGC-27 was detected by quantitative real-time reverse transcription-polymerase chain reaction （RT-PCR） and Western blotting.HGC-27 cells were employed to construct the stable GPR34 knockdown cell model in this study.Real-time RT-PCR and Western blotting were applied to validate the effect of short hairpin RNA （ShRNA） on the expression of GPR34 in HGC-27 gastric cells.The proliferation,migration of these cells were examined by Cell Counting Kit-8 and transwell.We also measured expression profile of PI3K/PDK1/AKT and ERK using Western blotting.Results：The ShRNA directed against GPR34 effectively inhibited both endogenous mRNA and protein expression levels of GPR34,and significantly down-regulated the expression of PIK3CB （P ＜ 0.01）,PIK3CD （P ＜ 0.01）,PDK1 （P ＜ 0.01）,phosphorylation of PDK1 （P ＜ 0.01）,Akt （P ＜ 0.01）,and ERK （P ＜ 0.01）.Furthermore,GPR34 knockdown resulted in an obvious reduction in HGC-27 cancer cell proliferation and migration activity （P ＜ 0.01）.Conclusions：GPR34 knockdown impairs the proliferation and migration of HGC-27 gastric cancer cells in vitro and provides a potential implication for therapy of gastric cancer.