GPR124 promotes trophoblast proliferation, migration, and invasion and inhibits trophoblast cell apoptosis and inflammation via JNK and P38 MAPK pathways

Early-onset preeclampsia, which occurrs before 34 weeks of gestation, is the most dangerous classification of preeclampsia, which is a pregnancy-specific disease that causes 1% of maternal deaths. G protein-coupled receptor 124 (GPR124) is significantly expressed at various stages of the human reproductive process, particularly during embryogenesis and angiogenesis. Our prior investigation demonstrated a notable decrease in GPR124 expression in the placentas of patients with early-onset preeclampsia compared to that in normal pregnancy placentas. However, there is a lack of extensive investigation into the molecular processes that contribute to the role of GPR124 in placenta development. This study aimed to examine the mechanisms by which GPR124 affects the occurrence of early-onset preeclampsia and its function in trophoblast. Proliferative, invasive, migratory, apoptotic, and inflammatory processes were identified in GPR124 knockdown, GPR124 overexpression, and normal HTR8/SVneo cells. The mechanism of GPR124-mediated cell function in GPR124 knockdown HTR8/SVneo cells was examined using inhibitors of the JNK or P38 MAPK pathway. Downregulation of GPR124 was found to significantly inhibit proliferation, invasion and migration, and promote apoptosis of HTR8/SVneo cells when compared to the control and GPR124 overexpression groups. This observation is consistent with the pathological characteristics of preeclampsia. In addition, GPR124 overexpression inhibits the secretion of pro-inflammatory cytokines interleukin (IL)-8 and interferon-γ (IFN-γ) while enhancing the secretion of the anti-inflammatory cytokine interleukin (IL)-4. Furthermore, GPR124 suppresses the activation of P-JNK and P-P38 within the JNK/P38 MAPK pathway. The invasion, apoptosis, and inflammation mediated by GPR124 were partially restored by suppressing the JNK and P38 MAPK pathways in HTR8/SVneo cells. GPR124 plays a crucial role in regulating trophoblast proliferation, invasion, migration, apoptosis, and inflammation via the JNK and P38 MAPK pathways. Furthermore, the effect of GPR124 on trophoblast suggests its involvement in the pathogenesis of early-onset preeclampsia.

GPR124 regulates murine brain embryonic angiogenesis and BBB formation by an intracellular domain-independent mechanism

The GPR124/RECK/WNT7 pathway is an essential regulator of CNS angiogenesis and blood-brain barrier (BBB) function. GPR124, a brain endothelial adhesion 7-pass transmembrane protein, associates with RECK, which binds and stabilizes newly synthesized WNT7, which is transferred to Frizzled (FZD) to initiate canonical b-catenin signaling. GPR124 remains enigmatic; while its extracellular domain (ECD) is essential, the poorly conserved intracellular domain (ICD) appears variably required in mammals versus zebrafish, potentially via adaptor protein bridging of GPR124/FZD ICDs. GPR124 ICD deletion impairs zebrafish angiogenesis, but paradoxically retains WNT7 signaling upon mammalian transfection. We thus investigated GPR124 ICD function by mouse deletion (Gpr124ΔC). Despite inefficiently expressed GPR124ΔC protein, Gpr124ΔC/ΔC mice could be born with normal cerebral cortex angiogenesis, versus Gpr124-/- embryonic lethality, forebrain avascularity and hemorrhage. Gpr124ΔC/ΔC vascular phenotypes were restricted to sporadic ganglionic eminence angiogenic defects, attributable to impaired GPR124ΔC protein expression. Further, Gpr124ΔC and recombinant GPR124 ECD rescued WNT7 signaling in culture upon brain endothelial Gpr124 knockdown. Thus, in mice, GPR124-regulated CNS forebrain angiogenesis and BBB function is exerted by ICD-independent functionality, extending the signaling mechanisms used by adhesion 7-pass transmembrane receptors.

Down-regulated Wnt7a and GPR124 in early-onset preeclampsia placentas reduce invasion and migration of trophoblast cells

OBJECTIVES

Preeclampsia (PE) is a disease specific to pregnancy that causes 9-10 % of maternal deaths. Early-onset PE (<34 weeks' gestation) is the most dangerous category of PE. Wnt7a and GPR124 (G protein-coupled receptor 124) are widely expressed in the human reproductive process. Especially during embryogenesis and tumorigenesis, Wnt7a plays a crucial role. However, few studies have examined the association between Wnt7a-GPR124 and early-onset PE. The aim of this study was to examine the significance of Wnt7a and GPR124 in early-onset PE as well as Wnt7a's role in trophoblast cells.

METHODS

Immunohistochemistry (IHC), real-time PCR, and western blotting (WB) were used to investigate Wnt7a and GPR124 expression in normal and early-onset PE placentas. Additionally, FACS, Transwell, and CCK-8 assays were used to diagnose Wnt7a involvement in migration, invasion, and proliferation.

RESULTS

In the early-onset PE group, Wnt7a and GPR124 expression was significantly lower than in the normal group, especially in the area of syncytiotrophoblasts (STBs) and extravillous trophoblasts (EVTs). A negative correlation was found between Wnt7a RNA and GPR124 expression (r=-0.42, p<0.01). However, the Wnt7a RNA expression level was positive correlated with PE severity. In further cellular functional experiments, knockdown of Wnt7a inhibits HTR8/SVeno cells invasion and migration but has little effect on proliferation and apoptosis.

CONCLUSIONS

Through the Wnt pathway, Wnt7a regulates trophoblast cell invasion and migration, and may contribute to early-onset preeclampsia pathogenesis. A molecular level study of Wnt7a will be needed to find downstream proteins and mechanisms of interaction.

CD44+ lung cancer stem cell-derived pericyte-like cells cause brain metastases through GPR124-enhanced trans-endothelial migration

Brain metastasis of lung cancer causes high mortality, but the exact mechanisms underlying the metastasis remain unclear. Here we report that vascular pericytes derived from CD44+ lung cancer stem cells (CSCs) in lung adenocarcinoma (ADC) potently cause brain metastases through the G-protein-coupled receptor 124 (GPR124)-enhanced trans-endothelial migration (TEM). CD44+ CSCs in perivascular niches generate the majority of vascular pericytes in lung ADC. CSC-derived pericyte-like cells (Cd-pericytes) exhibit remarkable TEM capacity to effectively intravasate into the vessel lumina, survive in the circulation, extravasate into the brain parenchyma, and then de-differentiate into tumorigenic CSCs to form metastases. Cd-pericytes uniquely express GPR124 that activates Wnt7-β-catenin signaling to enhance TEM capacity of Cd-pericytes for intravasation and extravasation, two critical steps during tumor metastasis. Furthermore, selective disruption of Cd-pericytes, GPR124, or the Wnt7-β-catenin signaling markedly reduces brain and liver metastases of lung ADC. Our findings uncover an unappreciated cellular and molecular paradigm driving tumor metastasis.

Thermosensitive hydrogel-based GPR124 delivery strategy for rebuilding blood-spinal cord barrier

Spinal cord injury (SCI) causes blood-spinal cord barrier (BSCB) disruption, leading to secondary damage, such as hemorrhagic infiltration, inflammatory response, and neuronal cell death. It is of great significance to rebuild the BSCB at the early stage of SCI to alleviate the secondary injury for better prognosis. Yet, current research involved in the reconstruction of BSCB is insufficient. Accordingly, we provide a thermosensitive hydrogel-based G protein-coupled receptor 124 (GPR124) delivery strategy for rebuilding BSCB. Herein, we firstly found that the expression of GPR124 decreased post-SCI and demonstrated that treatment with recombinant GPR124 could partially alleviate the disruption of BSCB post-SCI by restoring tight junctions (TJs) and promoting migration and tube formation of endothelial cells. Interestingly, GPR124 could also boost the energy metabolism of endothelial cells. However, the absence of physicochemical stability restricted the wide usage of GPR124. Hence, we fabricated a thermosensitive heparin-poloxamer (HP) hydrogel that demonstrated sustained GPR124 production and maintained the bioactivity of GPR124 (HP@124) for rebuilding the BSCB and eventually enhancing functional motor recovery post-SCI. HP@124 hydrogel can encapsulate GPR124 at the lesion site by injection, providing prolonged release, preserving wounded tissues, and filling injured tissue cavities. Consequently, it induces synergistically efficient integrated regulation by blocking BSCB rupture, decreasing fibrotic scar formation, minimizing inflammatory response, boosting remyelination, and regenerating axons. Mechanistically, giving GPR124 activates energy metabolism via elevating the expression of phosphoenolpyruvate carboxykinase 2 (PCK2), and eventually restores the poor state of endothelial cells. This research demonstrated that early intervention by combining GPR124 with bioactive multifunctional hydrogel may have tremendous promise for restoring locomotor recovery in patients with central nervous system disorders, in addition to a translational approach for the medical therapy of SCI.

Automated SSHHPS Analysis Predicts a Potential Host Protein Target Common to Several Neuroinvasive (+)ssRNA Viruses

Within the viral genome, short stretches of homologous host pathogen sequences (SSHHPS) span the protease cleavage sites. To identify host proteins that may be cleaved during infection, we searched the human proteome for viral protease cleavage sites (~20 amino acids). We developed a sequence-to-symptom tool, automating the search and pairing process. We used the viral protein sequence, PHI-BLAST, and UniProt database for gene ontologies and disease relationships. We applied the tool to nine neuroinvasive viruses: Venezuelan and Eastern Equine encephalitis virus (VEEV, EEEV); severe acute respiratory syndrome (SARS, SARS-CoV-2); Middle East respiratory syndrome (MERS); EV-71; Japanese encephalitis virus (JEV); West Nile (WNV); and Zika (ZIKV). A comparison of the hits identified a protein common to all nine viruses called ADGRA2 (GPR124). ADGRA2 was a predicted hit of the 3CL main protease and papain-like protease (PLpro) of SARS-CoV-2. ADGRA2 is an adhesion G protein-coupled receptor and a key endothelial regulator of brain-specific angiogenesis. It is a Wnt7A/Wnt7B specific coactivator of beta-catenin signaling and is essential for blood-brain barrier (BBB) integrity in central nervous system (CNS) diseases. We show the cleavage of the predicted sequences in MYOM1, VWF by the SARS-CoV-2 PLpro; DNAH8 (dynein) by the MERS PLpro; ADGRA2 by the alphaviral VEEV nsP2 protease; and POT1 by the SARS-CoV-2 and MERS PLpro.

G-protein-coupled receptor 124 promotes osteogenic differentiation of BMSCs through the Wnt/β-catenin pathway

Osteoporosis occurs frequently in women after menopause and old age, and it is very easy to cause osteoporotic fractures, resulting in disability and death. In osteoporosis patients, the potential of bone marrow mesenchymal stem cells (BMSCs) to differentiate into osteoblasts gradually is inhibited, leading to decreased new bone formation. In the current study, the potential effect of G-protein-coupled receptor 124 (GPR124) on the osteoblastic differentiation of BMSCs was determined. BMSCs were isolated and cultured in osteogenic media to induced osteogenic differentiation. Then, osteogenic differentiation was evaluated by Alizarin Red staining and ALP activity. The expression of osteogenic differentiation biomarkers, and Wnt/β-catenin signaling were determined by qRT-PCR and Western blotting. The results indicated that the expression of GPR124 was significantly increased during osteogenic differentiation of BMSCs. Moreover, GPR124 knockdown significantly inhibited osteoblastic differentiation and GPR124 overexpression promoted osteoblastic differentiation of BMSCs. GPR124 knockdown suppressed the activation of Wnt/β-catenin signaling pathway. What's more, the increased osteogenic differentiation induced by GPR124 overexpression was abolished by the inhibitor of Wnt/β-catenin pathway and Wnt7a knockdown. Taken together, GPR124 promotes osteogenic differentiation of BMSCs through the Wnt/β-catenin pathway and may serve as a potential target for enhancing osteogenesis of osteoporosis patients.

A RECK-WNT7 Receptor-Ligand Interaction Enables Isoform-Specific Regulation of Wnt Bioavailability

WNT7A and WNT7B control CNS angiogenesis and blood-brain barrier formation by activating endothelial Wnt/β-catenin signaling. The GPI-anchored protein RECK and adhesion G protein-coupled receptor GPR124 critically regulate WNT7-specific signaling in concert with FZD and LRP co-receptors. Here, we demonstrate that primarily the GPR124 ectodomain, but not its transmembrane and intracellular domains, mediates RECK/WNT7-induced canonical Wnt signaling. Moreover, RECK is the predominant binding partner of GPR124 in rat brain blood vessels in situ. WNT7A and WNT7B, but not WNT3A, directly bind to purified recombinant soluble RECK, full-length cell surface RECK, and the GPR124:RECK complex. Chemical cross-linking indicates that RECK and WNT7A associate with 1:1 stoichiometry, which stabilizes short-lived, active, monomeric, hydrophobic WNT7A. In contrast, free WNT7A rapidly converts into inactive, hydrophilic aggregates. Overall, RECK is a selective WNT7 receptor that mediates GPR124/FZD/LRP-dependent canonical Wnt/β-catenin signaling by stabilizing active cell surface WNT7, suggesting isoform-specific regulation of Wnt bioavailability.

GPR124 facilitates pericyte polarization and migration by regulating the formation of filopodia during ischemic injury

Prolonged occlusion of multiple microvessels causes microvascular injury. G protein-coupled receptor 124 (GPR124) has been reported to be required for maintaining central nervous system (CNS) angiogenesis and blood-brain barrier integrity. However, the molecular mechanisms by which GPR124 regulates pericytes during ischemia have remained elusive.

Methods: A microsphere embolism-induced ischemia model was used to evaluate the expression of GPR124 following microsphere embolism. Immunocytochemistry and stochastic optical reconstruction microscopy imaging were used to assess the expression and distribution of GPR124 in human brain vascular pericytes (HBVPs) and after the treatment with 3-morpholino-sydnonimine (SIN-1) or oxygen-glucose deprivation (OGD). The effect of GPR124 knockdown or overexpression on HBVP migration was analyzed in vitro using wound healing assays and a microfluidic device. GPR124 loss-of-function studies were performed in HBVPs and HEK293 cells using CRISPR-Cas9-mediated gene deletion. Time-lapse imaging was used to assess dynamic changes in the formation of filopodia in an individual cell. Finally, to explore the functional domains required for GPR124 activity, deletion mutants were constructed for each of the N-terminal domains.

Results: GPR124 expression was increased in pericytes following microsphere embolism. Morphological analysis showed localization of GPR124 to focal adhesions where GPR124 bound directly to the actin binding protein vinculin and upregulated Cdc42. SIN-1 or OGD treatment redistributed GPR124 to the leading edges of HBVPs where GPR124 signaling was required for pericyte filopodia formation and directional migration. Partial deletion of GPR124 domains decreased SIN-1-induced filopodia formation and cell migration.

Conclusion: Taken together, our results provide the first evidence for a role of GPR124 in pericyte migration under ischemic conditions and suggest that GPR124 was essential for Cdc42 activation and filopodia formation.

β-elemene enhances anticancer bone neoplasms efficacy of paclitaxel through regulation of GPR124 in bone neoplasms cells

The purpose of the present study was to investigate the anticancer effects of β-elemene and paclitaxel for bone neoplasms. MTT assay, reverse transcription-quantitative polymerase chain reaction, western blotting, flow cytometry and immunostaining were used to analyze the combined effects of β-elemene and paclitaxel both in vitro and in vivo. The results demonstrated that combined treatment of β-elemene and paclitaxel (β-elemene-paclitaxel) significantly inhibited growth and aggressiveness of U-2OS cells compared with either β-elemene or paclitaxel treatment alone. It was demonstrated that β-elemene promoted paclitaxel-induced apoptosis of U-2OS cells. Anti-apoptosis B-cell lymphoma (Bcl)-2 and Bcl-w genes were downregulated and pro-apoptotic Bcl-2-associated agonist of cell death and caspase-3 genes were upregulated in U-2OS cells following treatment with β-elemene-paclitaxel. Treatment of β-elemene-paclitaxel arrested the cell cycle and decreased cyclin-dependent kinase, cyclin-B1, P21 and P27 expression levels and decreased resistant genes alterations of ATP binding cassette subfamily B member 1, LDL receptor related protein and TS in U-2OS cells. Results demonstrated that β-elemene-paclitaxel decreased G-protein coupled receptor 124 (GPR124), vascular endothelial growth factor receptor, matrix metallopeptidase (MMP)-3, MMP-9 expression levels and increased endostatin, TIMP metallopeptidase inhibitor (TIMP)-1, TIMP-2 expression in U-2OS cells. In vivo assay demonstrated that β-elemene-paclitaxel treatment inhibited tumor growth of BALB/c-nu/nu nude mice and prolonged survival rate of tumor-bearing mice. Immunostaining demonstrated that β-elemene-paclitaxel treatment increased apoptotic bodies, GPR124 and increased endostatin, TIMP-1 and TIMP-2 expression in tumor tissues. In conclusion, these results suggest that the combined treatment of β-elemene-paclitaxel is more effective at inhibiting bone neoplasm growth than β-elemene or paclitaxel single treatment GPR124.

Possible involvement of orphan receptors GPR88 and GPR124 in the development of hypertension in spontaneously hypertensive rat

Hypertension (HBP) is a chronic disease characterized by increased blood pressure, which despite several treatments maintains a high morbi-mortality, which suggests that there are other mechanisms involved in this pathology, within which the orphan receptors could be candidates for the treatment of the HBP; these receptors are called orphan receptors because their ligand is unknown. These receptors have been suggested to participate in some pathologies because they are associated with various systems such as GPR88, which has been linked to the dopaminergic system, and GPR124 with angiogenesis, suggesting that these receptors could take part in HBP. Hence, the aim of this work was to study the expression of orphan receptors GPR88 and GPR124 in various tissues of normotensive and hypertensive rats. We used Wistar Kyoto (WKY) and spontaneously hypertensive rat (SHR) of 6-8 and 10-12 weeks of age and we determined systolic blood pressure (SBP), heart rate, as well as mRNA of GPR88 and GPR124 receptors by reverse transcription polymerase chain reaction (RT-PCR) in the aorta, heart, kidney, and brain. Our results showed that GPR88 and GPR124 were expressed in all analyzed tissues, but their expression is dependent on the age and development of HBP because their expression tends to be modified as HBP is established. Therefore, we conclude that GPR88 and GPR124 receptors may be involved in the development or maintenance of high blood pressure.

Chronic asthma results in cognitive dysfunction in immature mice

Asthma is the most common chronic childhood illness today. However, little attention is paid for the impacts of chronic asthma-induced hypoxia on cognitive function in children. The present study used immature mice to establish ovalbumin-induced chronic asthma model, and found that chronic asthma impaired learning and memory ability in Morris Water Maze test. Further study revealed that chronic asthma destroyed synaptic structure, impaired long-term potentiation (LTP) maintaining in the CA1 region of mouse hippocampal slices. We found that intermittent hypoxia during chronic asthma resulted in down-regulation of c-fos, Arc and neurogenesis, which was responsible for the impairment of learning and memory in immature mice. Moreover, our results showed that budesonide treatment alone was inadequate for attenuating chronic asthma-induced cognitive impairment. Therefore, our findings indicate that chronic asthma might result in cognitive dysfunction in children, and more attention should be paid for chronic asthma-induced brain damage in the clinical therapy.