Lysophosphatidic Acid Receptor Research Articles

Lysophosphatidic Acid (LPA) and Its Receptors in Mood Regulation: A Systematic Review of the Molecular Mechanisms and Therapeutic Potential

Mood disorders affect over 300 million individuals worldwide, often characterized by their chronic and refractory nature, posing significant threats to patient life. There has been a notable increase in mood disorders among American adolescents and young adults, with a rising number of suicide attempts and fatalities, highlighting a growing association between mood disorders and suicidal outcomes. Dysregulation within the neuroimmune–endocrine system is now recognized as one of the fundamental biological mechanisms underlying mood and mood disorders. Lysophosphatidic acid (LPA), a novel mediator of mood behavior, induces anxiety-like and depression-like phenotypes through its receptors LPA1 and LPA5, regulating synaptic neurotransmission and plasticity. Consequently, LPA has garnered substantial interest in the study of mood regulation. This study aimed to elucidate the molecular mechanisms of lysophosphatidic acid and its receptors, along with LPA receptor ligands, in mood regulation and to explore their potential therapeutic efficacy in treating mood disorders. A comprehensive literature search was conducted using the PubMed and Web of Science databases, identifying 208 articles through keyword searches up to June 2024. After excluding duplicates, irrelevant publications, and those restricted by open access limitations, 21 scientific papers were included in this review. The findings indicate that LPA/LPA receptor modulation could be beneficial in treating mood disorders, suggesting that pharmacological agents or gintonin, an extract from ginseng, may serve as effective therapeutic strategies. This study opens new avenues for future research into how lysophosphatidic acid and its receptors, as well as lysophosphatidic acid receptor ligands, influence emotional behavior in animals and humans.

Hypoxia Promotes Invadosome Formation by Lung Fibroblasts

Lung parenchymal hypoxia has emerged as a cardinal feature of idiopathic pulmonary fibrosis (IPF). Hypoxia promotes cancer cell invasion and metastasis through signaling that is dependent upon the lysophosphatidic acid (LPA) receptor, LPA1 (LPAR1). Abundant data indicate that LPA1-dependent signaling also enhances lung fibrogenesis in IPF. We recently reported that fibroblasts isolated from the lungs of individuals with IPF have an increased capacity to form subcellular matrix-degradative structures known as invadosomes, an event that correlates with the degree of lung fibrosis. We therefore hypothesized that hypoxia promotes invadosome formation in lung fibroblasts through LPA1-dependent signaling. Here, it is demonstrated that invadosome formation by fibroblasts from the lungs of individuals with advanced IPF is inhibited by both the tyrosine receptor kinase inhibitor nintedanib and inhibition of LPA1. In addition, exposure of normal human lung fibroblasts to either hypoxia or LPA increased their ability to form invadosomes. Mechanistically, the hypoxia-induced invadosome formation by lung fibroblasts was found to involve LPA1 and PDGFR-Akt signaling. We concluded that hypoxia increases the formation of invadosomes in lung fibroblasts through the LPA1 and PDGFR-Akt signaling axis, which represents a potential target for suppressing lung fibrosis.

LYSOPHOSPHATIDIC ACID METABOLISM AND SIGNALING IN HEART DISEASE.

Lysophosphatidic acid (LPA) is a bioactive lipid that is mainly produced by the secreted lysophospholipase D, autotaxin (ATX), and signals through at least six G protein-coupled receptors (LPA1-6). Extracellular LPA is degraded through lipid phosphate phosphatases (LPP1, LPP2, and LPP3) at the plasmamembrane, terminating LPA receptor signaling. The ATX-LPA-LPP3 pathway is critically involved in a wide range of physiological processes, including cell survival, migration, proliferation, angiogenesis, and organismal development. Similarly, dysregulation of this pathway has been linked to many pathological processes, including cardiovascular disease. This review summarizes and interprets current literature examining the regulation and role of the ATX-LPA-LPP3 axis in heart disease. Specifically, the contribution of altered LPA metabolism via ATX and LPP3 and resulting changes to LPA receptor signaling in obesity cardiomyopathy, cardiac mitochondrial dysfunction, myocardial infarction/ischemia-reperfusion injury, hypertrophic cardiomyopathy, and aortic valve stenosis is discussed.

GPCR-Gα13 Involvement in Mitochondrial Function, Oxidative Stress, and Prostate Cancer

Gα13 and Gα12, encoded by the GNA13 and GNA12 genes, respectively, are members of the G12 family of Gα proteins that, along with their associated Gβγ subunits, mediate signaling from specific G protein-coupled receptors (GPCRs). Advanced prostate cancers have increased expression of GPCRs such as CXC Motif Chemokine Receptor 4 (CXCR4), lysophosphatidic acid receptor (LPAR), and protease activated receptor 1 (PAR-1). These GPCRs signal through either the G12 family, or through Gα13 exclusively, often in addition to other G proteins. The effect of Gα13 can be distinct from that of Gα12, and the role of Gα13 in prostate cancer initiation and progression is largely unexplored. The oncogenic effect of Gα13 on cell migration and invasion in prostate cancer has been characterized, but little is known about other biological processes such as mitochondrial function and oxidative stress. Current knowledge on the link between Gα13 and oxidative stress is based on animal studies in which GPCR-Gα13 signaling decreased superoxide levels, and the overexpression of constitutively active Gα13 promoted antioxidant gene activation. In human samples, mitochondrial superoxide dismutase 2 (SOD2) correlates with prostate cancer risk and prognostic Gleason grade. However, overexpression of SOD2 in prostate cancer cells yielded conflicting results on cell growth and survival under basal versus oxidative stress conditions. Hence, it is necessary to explore the effect of Gα13 on prostate cancer tumorigenesis, as well as the effect of Gα13 on SOD2 in prostate cancer cell growth under oxidative stress conditions.

A Reliable System for Quantitative G-Protein Activation Imaging in Cancer Cells

Fluorescence resonance energy transfer (FRET) biosensors have proven to be an indispensable tool in cell biology and, more specifically, in the study of G-protein signalling. The best method of measuring the activation status or FRET state of a biosensor is often fluorescence lifetime imaging microscopy (FLIM), as it does away with many disadvantages inherent to fluorescence intensity-based methods and is easily quantitated. Despite the significant potential, there is a lack of reliable FLIM-FRET biosensors, and the data processing and analysis workflows reported previously face reproducibility challenges. Here, we established a system in live primary mouse pancreatic ductal adenocarcinoma cells, where we can detect the activation of an mNeonGreen-Gαi3-mCherry-Gγ2 biosensor through the lysophosphatidic acid receptor (LPAR) with 2-photon time-correlated single-photon counting (TCSPC) FLIM. This combination gave a superior signal to the commonly used mTurquoise2-mVenus G-protein biosensor. This system has potential as a platform for drug screening, or to answer basic cell biology questions in the field of G-protein signalling.

Lysophosphatidic Acid Receptor 3 (LPA3): Signaling and Phosphorylation Sites.

LPA3 receptors were expressed in TREx HEK 293 cells, and their signaling and phosphorylation were studied. The agonist, lysophosphatidic acid (LPA), increased intracellular calcium and ERK phosphorylation through pertussis toxin-insensitive processes. Phorbol myristate acetate, but not LPA, desensitizes LPA3-mediated calcium signaling, the agonists, and the phorbol ester-induced LPA3 internalization. Pitstop 2 (clathrin heavy chain inhibitor) markedly reduced LPA-induced receptor internalization; in contrast, phorbol ester-induced internalization was only delayed. LPA induced rapid β-arrestin-LPA3 receptor association. The agonist and the phorbol ester-induced marked LPA3 receptor phosphorylation, and phosphorylation sites were detected using mass spectrometry. Phosphorylated residues were detected in the intracellular loop 3 (S221, T224, S225, and S229) and in the carboxyl terminus (S321, S325, S331, T333, S335, Y337, and S343). Interestingly, phosphorylation sites are within sequences predicted to constitute β-arrestin binding sites. These data provide insight into LPA3 receptor signaling and regulation.

Lysophosphatidic Acid Receptor 1 (LPA1) Antagonists as Potential Migrastatics for Triple Negative Breast Cancer.

Metastasis is responsible for about 90 % of cancer deaths. Anti-metastatic drugs, termed as migrastatics, offer a distinctive therapeutic approach to address cancer migration and invasion. However, therapeutic exploitation of metastasis-specific targets remains limited, and the effective prevention and suppression of metastatic cancer continue to be elusive. Lysophosphatidic acid receptor 1 (LPA1) is activated by an endogenous lipid molecule LPA, leading to a diverse array of cellular activities. Previous studies have shown that the LPA/LPA1 axis supports the progression of metastasis for many types of cancer. In this study, we report the synthesis and biological evaluation of fluorine-containing triazole derivatives as potent LPA1 antagonists, offering potential as migrastatic drugs for triple negative breast cancer (TNBC). In particular, compound 12 f, the most potent and highly selective in this series with an IC50 value of 16.0 nM in the cAMP assay and 18.4 nM in the calcium mobilization assay, inhibited cell survival, migration, and invasion in the TNBC cell line. Interestingly, the compound did not induce apoptosis in TNBC cells and demonstrated no cytotoxic effects. These results highlight the potential of LPA1 as a migrastatic target. Consequently, the LPA1 antagonists developed in this study hold promise as potential migrastatic candidates for TNBC.

LPA3 Receptor Phosphorylation Sites: Roles in Signaling and Internalization.

Lysophosphatidic acid (LPA) type 3 (LPA3) receptor mutants were generated in which the sites detected phosphorylated were substituted by non-phosphorylatable amino acids. Substitutions were made in the intracellular loop 3 (IL3 mutant), the carboxyl terminus (Ctail), and both domains (IL3/Ctail). The wild-type (WT) receptor and the mutants were expressed in T-REx HEK293 cells, and the consequences of the substitutions were analyzed employing different functional parameters. Agonist- and LPA-mediated receptor phosphorylation was diminished in the IL3 and Ctail mutants and essentially abolished in the IL3/Ctail mutant, confirming that the main phosphorylation sites are present in both domains and their role in receptor phosphorylation eliminated by substitution and distributed in both domains. The WT and mutant receptors increased intracellular calcium and ERK 1/2 phosphorylation in response to LPA and PMA. The agonist, Ki16425, diminished baseline intracellular calcium, which suggests some receptor endogenous activity. Similarly, baseline ERK1/2 phosphorylation was diminished by Ki16425. An increase in baseline ERK phosphorylation was detected in the IL3/Ctail mutant. LPA and PMA-induced receptor interaction with β-arrestin 2 and LPA3 internalization were severely diminished in cells expressing the mutants. Mutant-expressing cells also exhibit increased baseline proliferation and response to different stimuli, which were inhibited by the antagonist Ki16425, suggesting a role of LPA receptors in this process. Migration in response to different attractants was markedly increased in the Ctail mutant, which the Ki16425 antagonist also attenuated. Our data experimentally show that receptor phosphorylation in the distinct domains is relevant for LPA3 receptor function.

Pharmacokinetics of Fipaxalparant, a Small-Molecule Selective Negative Allosteric Modulatorof Lysophosphatidic Acid Receptor 1, and the Effect of Food in Healthy Volunteers.

Dysregulated lysophosphatidic acid receptor 1 (LPAR1) signaling is implicated in fibrotic diseases, including systemic sclerosis (SSc) and idiopathic pulmonary fibrosis (IPF). Fipaxalparant (HZN-825) is a small molecule acting as a negative allosteric modulator of LPAR1 and is in phase 2 clinical evaluations for treating diffuse cutaneous SSc and IPF. This open-label, phase 1 study examined the pharmacokinetics (PKs), food effect, and safety of fipaxalparant in healthy volunteers. Dose proportionality was evaluated for fipaxalparant single doses of 150, 300, and 450mg under fasted conditions. Food effect was tested with a 450-mg single dose under fasted conditions or with a high-fat meal. Multiple-dose PKs for twice-daily dosing of either 300 or 450mg with low- or high-fat meals was also assessed. Fipaxalparant was safe and well tolerated in healthy volunteers (n = 36) under all conditions. Fipaxalparant exposure increased in a less than dose-proportional manner from 150 to 450mg. At 450mg, a high-fat meal increased the maximum observed concentration and area under the curve by approximately 1.9- and 2.1-fold, respectively. These results, combined with prior preclinical and phase 2a data, informed dose selection of fipaxalparant 300mg once and twice daily with a meal for phase 2b studies.

Integration of multi-omics analysis reveals metabolic alterations of B lymphocytes in systemic lupus erythematosus

ObjectiveTo link changes in the B-cell transcriptome from systemic lupus erythematosus (SLE) patients with those in their macroenvironment, including cellular and fluidic components. MethodsAnalysis was performed on 363 patients and 508 controls, encompassing transcriptomics, metabolomics, and clinical data. B-cell and whole-blood transcriptomes were analysed using DESeq and GSEA. Plasma and urine metabolomics peak changes were quantified and annotated using Ceu Mass Mediator database. Common sources of variation were identified using MOFA integration analysis. ResultsCellular macroenvironment was enriched in cytokines, stress responses, lipidic synthesis/mobility pathways and nucleotide degradation. B cells shared these pathways, except nucleotide degradation diverted to nucleotide salvage pathway, and distinct glycosylation, LPA receptors and Schlafen proteins. ConclusionsB cells showed metabolic changes shared with their macroenvironment and unique changes directly or indirectly induced by IFN-α signalling. This study underscores the importance of understanding the interplay between B cells and their macroenvironment in SLE pathology.

Discovery of a brain penetrant small molecule antagonist targeting LPA1 receptors to reduce neuroinflammation and promote remyelination in multiple sclerosis

Multiple sclerosis (MS) is a chronic neurological disease characterized by inflammatory demyelination that disrupts neuronal transmission resulting in neurodegeneration progressive disability. While current treatments focus on immunosuppression to limit inflammation and further myelin loss, no approved therapies effectively promote remyelination to mitigate the progressive disability associated with chronic demyelination. Lysophosphatidic acid (LPA) is a pro-inflammatory lipid that is upregulated in MS patient plasma and cerebrospinal fluid (CSF). LPA activates the LPA1 receptor, resulting in elevated CNS cytokine and chemokine levels, infiltration of immune cells, and microglial/astrocyte activation. This results in a neuroinflammatory response leading to demyelination and suppressed remyelination. A medicinal chemistry effort identified PIPE-791, an oral, brain-penetrant, LPA1 antagonist. PIPE-791 was characterized in vitro and in vivo and was found to be a potent, selective LPA1 antagonist with slow receptor off-rate kinetics. In vitro, PIPE-791 induced OPC differentiation and promoted remyelination following a demyelinating insult. PIPE-791 further mitigated the macrophage-mediated inhibition of OPC differentiation and inhibited microglial and fibroblast activation. In vivo, the compound readily crossed the blood–brain barrier and blocked LPA1 in the CNS after oral dosing. Direct dosing of PIPE-791 in vivo increased oligodendrocyte number, and in the mouse experimental autoimmune encephalomyelitis (EAE) model of MS, we observed that PIPE-791 promoted myelination, reduced neuroinflammation, and restored visual evoked potential latencies (VEP). These findings support targeting LPA1 for remyelination and encourage development of PIPE-791 for treating MS patients with advantages not seen with current immunosuppressive disease modifying therapies.

CYRI-B mediated macropinocytosis drives metastasis via lysophosphatidic acid receptor uptake.

Pancreatic ductal adenocarcinoma carries a dismal prognosis, with high rates of metastasis and few treatment options. Hyperactivation of KRAS in almost all tumours drives RAC1 activation, conferring enhanced migratory and proliferative capacity as well as macropinocytosis. Macropinocytosis is well understood as a nutrient scavenging mechanism, but little is known about its functions in trafficking of signaling receptors. We find that CYRI-B is highly expressed in pancreatic tumours in a mouse model of KRAS and p53-driven pancreatic cancer. Deletion of Cyrib (the gene encoding CYRI-B protein) accelerates tumourigenesis, leading to enhanced ERK and JNK-induced proliferation in precancerous lesions, indicating a potential role as a buffer of RAC1 hyperactivation in early stages. However, as disease progresses, loss of CYRI-B inhibits metastasis. CYRI-B depleted tumour cells show reduced chemotactic responses to lysophosphatidic acid, a major driver of tumour spread, due to impaired macropinocytic uptake of the lysophosphatidic acid receptor-1. Overall, we implicate CYRI-B as a mediator of growth and signaling in pancreatic cancer, providing new insights into pathways controlling metastasis.

LPA-induced expression of CCN2 in muscular fibro/adipogenic progenitors (FAPs): Unraveling cellular communication networks

Cellular Communication Network Factor 2, CCN2, is a profibrotic cytokine implicated in physiological and pathological processes in mammals. The expression of CCN2 is markedly increased in dystrophic muscles. Interestingly, diminishing CCN2 genetically or inhibiting its function improves the phenotypes of chronic muscular fibrosis in rodent models. Elucidating the cell-specific mechanisms behind the induction of CCN2 is a fundamental step in understanding its relevance in muscular dystrophies. Here, we show that the small lipids LPA and 2S-OMPT induce CCN2 expression in fibro/adipogenic progenitors (FAPs) through the activation of the LPA1 receptor and, to a lower extent, by also the LPA6 receptor. These cells show a stronger induction than myoblasts or myotubes. We show that the LPA/LPARs axis requires ROCK kinase activity and organized actin cytoskeleton upstream of YAP/TAZ signaling effectors to upregulate CCN2 levels, suggesting that mechanical signals are part of the mechanism behind this process. In conclusion, we explored the role of the LPA/LPAR axis on CCN2 expression, showing a strong cytoskeletal-dependent response in muscular FAPs.

Lysophosphatidic Acid Receptor 3 Activation Is Involved in the Regulation of Erythrocyte Differentiation Through Ferroptosis

Ferroptosis, a unique form of programmed cell death trigged by lipid peroxidation and iron accumulation, has been implicated in embryonic erythropoiesis and aging. Our previous research demonstrated that lysophosphatidic acid receptor 3 (LPA3) activation mitigated oxidative stress in progeria cells and accelerate the recovery of acute-anemia in mice. Given that both processes involve iron metabolism, we hypothesized that LPA3 activation might mediate cellular ferroptosis. In this study, we used LPA3 agonists 1‐Oleoyl‐2‐O‐methyl‐rac‐glycerophosphothionate (OMPT) to activate LPA3 and examine its effects on the ferroptosis process. OMPT treatment elevated anti-ferroptosis genes protein expression, including solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4), heme oxygenase-1 (HO-1), and ferritin heavy chain (FTH1) in erastin-induced cells. Furthermore, OMPT reduced lipid peroxidation and intracellular ferrous iron accumulation, as evidenced by C11 BODIPYTM 581/591 Lipid Peroxidation Sensor and FerroOrange staining. These observations were validated by applying LPAR3 siRNA in the experiments mentioned above. In addition, the protein expression level of nuclear factor erythroid 2-related factor (NRF2), a key regulator of oxidative stress regulator, was also enhanced in OMPT treated cells. Lastly, we verified that LPA3 plays a critical role in erastin-induced ferroptotic human 25 erythroleukemia K562 cells. OMPT rescued the erythropoiesis defect caused by erastin in K562 cells through using Gly A promoter luciferase assay. Taken together, our findings suggest that LPA3 activation inhibits cell ferroptosis by suppressing lipid oxidation and iron accumulation, indicating that ferroptosis could potentially serve as a link between LPA3, aging and erythropoiesis. MOST 110-2311-B-002-026 MOST 111-2311-B-002-007. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Lysophosphatidic acid (LPA) receptor-mediated signaling regulates hypoxia-induced biological functions of lymphatic endothelial cells

The tumor microenvironment is an extremely complex composed of cancer cells and various non-cancer cells, including lymphatic endothelial cells. Lysophosphatidic acid (LPA) receptors (LPA1 to LPA6) activate a variety of malignant properties in human malignancies. In the present study, we examined the roles of LPA receptor-mediated signaling in biological responses of lymphatic endothelial SVEC4-10 cells induced by hypoxia. Lpar1, Lpar2 and Lpar3 expressions were decreased in SVEC4-10 cells cultured at hypoxic conditions (1 % O2). LPA had no impact on the cell growth activity of SVEC4-10 cells in 21 % O2 culture conditions. Conversely, the cell growth activity of SVEC4-10 cells in 1 % O2 culture conditions was reduced by LPA. The cell motile activity of SVEC4-10 cells was elevated by 1 % O2 culture conditions. GRI-977143 (LPA2 agonist) and (2S)-OMPT (LPA3 agonist) stimulated SVEC4-10 cell motility as well as AM966 (LPA1 antagonist). In tube formation assay, the tube formation of SVEC4-10 cells in 1 % O2 culture conditions was markedly increased, in comparison with 21 % O2. GRI-977143 and (2S)-OMPT elevated the tube formation of SVEC4-10 cells. Furthermore, the tube formation of SVEC4-10 cells was increased by AM966. These results suggest that LPA receptor-mediated signaling contributes to the modulation of hypoxic-induced biological functions of lymphatic endothelial cells.

Design, synthesis and evaluation of new thiazolidin-4-ones as LPA1 receptor antagonists for breast cancer therapy.

Aim: Breast cancer has been a leading cause of mortality among women worldwide in recent years. Targeting the lysophosphatidic acid(LPA)-LPA1 pathway using small molecules could improve breast cancer therapy. Materials & methods: Thiazolidin-4-ones were developed and tested on MCF-7 cancer cells, and active compounds were analyzed for their effects on apoptosis, migrationangiogenesisand LPA1 protein and gene expression. Results & conclusion: Compounds TZ-4 and TZ-6 effectively reduced the migration of MCF-7 cells, and induced apoptosis. TZ-4, TZ-6, TZ-8 and TZ-14 significantly reduced the LPA1 protein, LPA1 and angiogenesis gene expression in treated MCF-7 cells. Molecular docking and molecular dynamic simulation studies reveal the ligand interactions and stability of the LPA1-ligand complex. Developed thiazolidin-4-ones showed great potential as an LPA1-targeted approach to combating breast cancer.

Lysophosphatidic Acid Receptor 1 Plays a Pathogenic Role in Permanent Brain Ischemic Stroke by Modulating Neuroinflammatory Responses.

Lysophosphatidic acid receptor 1 (LPA1) plays a critical role in brain injury following a transient brain ischemic stroke. However, its role in permanent brain ischemic stroke remains unknown. To address this, we investigated whether LPA1 could contribute to brain injury of mice challenged by permanent middle cerebral artery occlusion (pMCAO). A selective LPA1 antagonist (AM152) was used as a pharmacological tool for this investigation. When AM152 was given to pMCAO-challenged mice one hour after occlusion, pMCAO-induced brain damage such as brain infarction, functional neurological deficits, apoptosis, and blood-brain barrier disruption was significantly attenuated. Histological analyses demonstrated that AM152 administration attenuated microglial activation and proliferation in injured brain after pMCAO challenge. AM152 administration also attenuated abnormal neuroinflammatory responses by decreasing expression levels of pro-inflammatory cytokines while increasing expression levels of anti-inflammatory cytokines in the injured brain. As underlying effector pathways, NF-κB, MAPKs (ERK1/2, p38, and JNKs), and PI3K/Akt were found to be involved in LPA1-dependent pathogenesis. Collectively, these results demonstrate that LPA1 can contribute to brain injury by permanent ischemic stroke, along with relevant pathogenic events in an injured brain.

LPA5-Dependent signaling regulates regeneration of the intestinal epithelium following irradiation.

Lysophosphatidic acid (LPA) is a bioactive lipid molecule that regulates a wide array of cellular functions, including proliferation, differentiation, and survival, via activation of cognate receptors. The LPA5 receptor is highly expressed in the intestinal epithelium, but its function in restoring intestinal epithelial integrity following injury has not been examined. Here, we use a radiation-induced injury model to study the role of LPA5 in regulating intestinal epithelial regeneration. Control mice (Lpar5f/f) and mice with an inducible, epithelial cell-specific deletion of Lpar5 in the small intestine (Lpar5IECKO) were subjected to 10 Gy total body X-ray irradiation and analyzed during recovery. Repair of the intestinal mucosa was delayed in Lpar5IECKO mice with reduced epithelial proliferation and increased crypt cell apoptosis. These effects were accompanied by reduced numbers of OLFM4+ intestinal stem cells (ISCs). The effects of LPA5 on ISCs were corroborated by studies using organoids derived from Lgr5-lineage tracking reporter mice with deletion of Lpar5 in Lgr5+-stem cells (Lgr5Cont or Lgr5ΔLpar5). Irradiation of organoids resulted in fewer numbers of Lgr5ΔLpar5 organoids retaining Lgr5+-derived progenitor cells compared with Lgr5Cont organoids. Finally, we observed that impaired regeneration in Lpar5IECKO mice was associated with reduced numbers of Paneth cells and decreased expression of Yes-associated protein (YAP), a critical factor for intestinal epithelial repair. Our study highlights a novel role for LPA5 in regeneration of the intestinal epithelium following irradiation and its effect on the maintenance of Paneth cells that support the stem cell niche.NEW & NOTEWORTHY We used mice lacking expression of the lysophosphatidic acid receptor 5 (LPA5) in intestinal epithelial cells and intestinal organoids to show that the LPA5 receptor protects intestinal stem cells and progenitors from radiation-induced injury. We show that LPA5 induces YAP signaling and regulates Paneth cells.

Regulation of cellular responses to X-ray irradiation through the activation of lysophosphatidic acid (LPA) receptor-3 (LPA3) and LPA2 in osteosarcoma cells

Lysophosphatidic acid (LPA) binds to its specific G protein-coupled LPA receptors (LPA1 to LPA6), resulting in the activation of various cellular functions. LPA receptor-mediated signaling facilitates tumor progression in human malignancies. In the present study, we investigated whether LPA receptor-mediated signaling contributes to cellular responses to X-ray irradiation in osteosarcoma MG-63 cells. After X-ray irradiation (2, 4 and 8 Gy), LPAR2 and LPAR3 expression levels in MG-63 cells were significantly elevated in a dose-dependent manner, but no change of LPAR1 expression level was observed. The cell growth activities of MG-63 cells irradiated with X-rays (2, 4 and 8 Gy) were reduced by LPA. Conversely, LPA3 agonist (2 S)-OMPT enhanced the cell growth activities of X-ray irradiated MG-63 cells. The cell movement of MG-63 cells exposed to X-ray irradiation (8 Gy) was inhibited by (2 S)OMPT. In cell survival assay, (2 S)-OMPT suppressed the cell survival to cisplatin (CDDP) of MG-63 cells irradiated with X-rays (8 Gy). The cell survival to CDDP of X-ray irradiated cells was elevated by LPA3 knockdown. Moreover, we evaluated the effects of LPA2 on the cell survival to CDDP of MG-63 cells exposed to X-ray irradiation (8 Gy). The cell survival to CDDP of X-ray irradiated cells was increased by LPA2 agonist GRI-977143 and reduced by LPA2 knockdown. These results suggest that LPA receptor-signaling participates in the modulation of cellular functions induced by X-ray irradiation in osteosarcoma cells.

Identification of a Curtius Rearrangement Byproduct in LPA1 Antagonist (BMS-986020) Synthesis

BMS-986020 was developed as an antagonist of the LPA1 receptor for the treatment of lung fibrosis (Idiopathic Pulmonary Fibrosis (IPF)). During the development of BMS-986020, a high percentage byproduct was observed in the mother liquor of a Curtius rearrangement reaction. The structure identification and formation mechanism of this unknown byproduct was deemed necessary to understand for further the reaction optimization and knowledge generation for the project. The characterization process required a multifaceted approach utilizing LC-HRMS, VT-NMR, and HPLC isolation. The investigation’s final result implicated the reaction base as the root cause of the byproduct formation and indicated a nitrene-iminium reaction pathway to form the byproduct.