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Orphan G Protein Coupled Receptors (GPCRs) are GPCRs whose endogenous ligands are unknown or still debated. Due to the lack of pharmacological modulators, the physiological function of orphan GPCRs is understudied. However, relevant physiological roles associated with orphan GPCRs have been revealed by analysis of animal models and genome wide association studies illuminating an untapped potential for drug discovery. G Protein Coupled Receptor class C Group 5 Member B (GPRC5B) is among the most expressed GPCRs in the central nervous system. Thus, the expression profiling of GPRC5B is an essential step toward understanding GPRC5B function in health and disease. In this study, we generated new GPRC5B polyclonal antibodies and investigated the expression levels of GPRC5B across different organs and brain regions. We identified high levels of GPRC5B glycosylation both in transfected cells and in mouse brain. Moreover, Show less

Numerous studies have focused on the molecular signaling pathways that govern the development and growth of lymphatics in the hopes of elucidating promising druggable targets. G protein-coupled receptors (GPCRs) are currently the largest family of membrane receptors targeted by FDA-approved drugs, but there remain many unexplored receptors, including orphan GPCRs with no known biological ligand or physiological function. Thus, we sought to illuminate the cadre of GPCRs expressed at high levels in lymphatic endothelial cells and identified four orphan receptors: GPRC5B, AGDRF5/GPR116, FZD8 and GPR61. Compared to blood endothelial cells, GPRC5B is the most abundant GPCR expressed in cultured human lymphatic endothelial cells (LECs), and in situ RNAscope shows high mRNA levels in lymphatics of mice. Using genetic engineering approaches in both zebrafish and mice, we characterized the function of GPRC5B in lymphatic development. Morphant Show less

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare type of vacuolating leukodystrophy (white matter disorder), which is mainly caused by defects in MLC1 or glial cell adhesion molecule (GlialCAM) proteins. In addition, autoantibodies to GlialCAM are involved in the pathology of multiple sclerosis. Show less

Diabetes is a serious disease that could greatly increase the risk of cardiovascular complications, whereas the underlying pathology of DN is still unknown. GPRC5B is a member of the RAIG subfamily of type 3 (family C) GPCR, and its role in DN is still unclear. To unveil the role of GPRC5B in diabetic nephropathy (DN) progression and investigate the potential signaling pathway. Podocytes were stimulated with high glucose and expression of GPRC5B was analyzed by qPCR and western blot. Then the level of GPRC5B was depleted by siRNA transfection and inflammatory cytokine level was monitored by ELISA assay. The ECM depostion and the activation of NF-κB pathway were detected by Immunoblot. We investigated the possible role of GPRC5B in the pathology of diabetic nephropathy. We found GPRC5B was highly expressed in high glocuse (HG) induced podocytes. The depletion of GPRC5B inhibited HG induced cell inflammation. In addition, the ablation of GPRC5B suppressed the HG induced ECM deposition. We further found GPRC5B could alleviate the inflammation and extracellular matrix deposition of HG-induced podocytes through NF-κB pathway. We therefore thought GPRC5B could serve as a promising target for the treatment of diabetic nephropathy. G-protein-coupled receptors. Show less

Atherosclerosis is driven by an inflammatory process of the vascular wall. The novel orphan G-protein coupled receptor 5B of family C (GPRC5B) is involved in drosophila sugar and lipid metabolism as well as mice adipose tissue inflammation. Here, we investigated the role of GPRC5B in the pro-atherogenic mechanisms of hyperglycemia and vascular inflammation. Immortalized and primary endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) were used for stimulation with high glucose or different cytokines. Adenoviral- or plasmid-driven GPRC5B overexpression and siRNA-mediated knockdown were performed in these cells to analyze functional and mechanistic pathways of GPRC5B. In ECs and VSMCs, stimulation with high glucose, TNFα or LPS induced a significant upregulation of endogenous GPRC5B mRNA and protein levels. GPRC5B overexpression and knockdown increased and attenuated, respectively, the expression of the pro-inflammatory cytokines TNFα, IL-1β, IL-6 as well as the pro-atherogenic vascular adhesion molecules ICAM-1 and VCAM-1. Furthermore, the expression and activity of the metalloproteinase MMP-9, a component of atherosclerotic plaque stabilization, were significantly enhanced by GPRC5B overexpression. Mechanistically, GPRC5B increased the phosphorylation of ERK1/2 and activated NFκB through a direct interaction with the tyrosine kinase Fyn. Our findings demonstrate that GPRC5B is upregulated in response to high glucose and pro-inflammatory signaling. GPRC5B functionally modulates the inflammatory activity in cells of the vascular wall, suggesting a pro-atherogenic GPRC5B-dependent positive feedback loop via Fyn and NFκB. Thus, GPRC5B warrants further attention as a novel pharmacological target for the treatment of vascular inflammation and possibly atherogenesis. Show less

Fibrosis is a condition characterized by the overproduction of extracellular matrix (ECM) components (e.g., collagen) in the myofibroblasts, causing tissue hardening and eventual organ dysfunction. Currently, the molecular mechanisms that regulate ECM production in the myofibroblasts are still obscure. In this study, we investigated the function of GPRC5B in the cardiac and lung myofibroblasts using real-time RT-PCR and siRNA-mediated knockdown. We discovered a significantly high expression of Gprc5b in the tissues of the fibrosis mice models and confirmed that Gprc5b was consistently expressed in the myofibroblasts of fibrotic hearts and lungs. We also found that Gprc5b expression was associated and may be dependent on the actin-MRTF-SRF signaling pathway. Notably, we observed that Gprc5b knockdown reduced the expression of collagen genes in the cardiac and lung myofibroblasts. Therefore, our findings reveal that GPRC5B enhances collagen production in the myofibroblasts, which directly promotes fibrosis in the tissues. Show less

Radioiodine-refractory thyroid cancers have poor outcomes and limited therapeutic options (tyrosine kinase inhibitors) due to transient efficacy and toxicity of treatments. Therefore, combinatorial treatments with new therapeutic approaches are needed. Many studies link G protein-coupled receptors (GPCRs) to cancer cell biology. To perform a specific atlas of GPCR expression in progressive and refractory thyroid cancer to identify potential targets among GPCRs aiming at drug repositioning. We analyzed samples from tumor and normal thyroid tissues from 17 patients with refractory thyroid cancer (12 papillary thyroid cancers [PTCs] and 5 follicular thyroid cancers [FTCs]). We assessed GPCR mRNA expression using NanoString technology with a custom panel of 371 GPCRs. The data were compared with public repositories and pharmacological databases to identify eligible drugs. The analysis of prognostic value of genes was also performed with TCGA datasets. With our transcriptomic analysis, 4 receptors were found to be downregulated in FTC (VIPR1, ADGRL2/LPHN2, ADGRA3, and ADGRV1). In PTC, 24 receptors were deregulated, 7 of which were also identified by bioinformatics analyses of publicly available datasets on primary thyroid cancers (VIPR1, ADORA1, GPRC5B, P2RY8, GABBR2, CYSLTR2, and LPAR5). Among all the differentially expressed genes, 22 GPCRs are the target of approved drugs and some GPCRs are also associated with prognostic factors. For the first time, we performed GPCR mRNA expression profiling in progressive and refractory thyroid cancers. These findings provide an opportunity to identify potential therapeutic targets for drug repositioning and precision medicine in radioiodine-refractory thyroid cancer. Show less

Currently, a comprehensive method for exploration of transcriptional regulation has not been well established. We explored a novel pipeline to analyze transcriptional regulation using co-analysis of RNA sequencing (RNA-seq), assay for transposase-accessible chromatin using sequencing (ATAC-seq), and chromatin immunoprecipitation with high-throughput sequencing (ChIP-seq). The G protein-coupled receptors (GPCRs) possibly associated with macrophages were further filtered using a reduced-Cox regression model. ATAC-seq profiles were used to map the chromatin accessibility of the GPRC5B promoter region. Pearson analysis was performed to identify the transcription factor (TF) whose expression was correlated with open chromatin regions of GPRC5B promoter. ChIP-seq profiles were obtained to confirm the physical binding of GATA4 and its predicted binding regions. For verification, quantitative polymerase chain reaction (qPCR) and multidimensional database validations were performed. The reduced-Cox regression model revealed the prognostic value of GPRC5B. A novel pipeline for TF exploration was proposed. With our novel pipeline, we first identified chr16:19884686-19885185 as a reproducible open chromatin region in the GPRC5B promoter. Thereafter, we confirmed the correlation between GATA4 expression and the accessibility of this region, confirmed its physical binding, and proved GPRC5B, correlated with macrophages, was a key GPCR affecting COAD prognosis. Further, with our novel pipeline, TF GATA4 was identified as a direct upstream of GPRC5B. This study proposed a novel pipeline for TF exploration and provided a theoretical basis for COAD therapy. Show less

The overall survival of metastatic colon adenocarcinoma (COAD) remains poor, so it is important to explore the mechanisms of metastasis and invasion. This study aimed to identify invasion-related genetic markers for prognosis prediction in patients with COAD. Three molecular subtypes (C1, C2, and C3) were obtained based on 97 metastasis-related genes in 365 COAD samples from The Cancer Genome Atlas (TCGA). A total of 983 differentially expressed genes (DEGs) were identified among the different subtypes by using the limma package. A 6-gene signature (ITLN1, HOXD9, TSPAN11, GPRC5B, TIMP1, and CXCL13) was constructed via Lasso-Cox analysis. The signature showed strong robustness and could be used in the training, testing, and external validation (GSE17537) cohorts with stable predictive efficiency. Compared with other published signatures, our model showed better performance in predicting outcomes. Pan-cancer expression analysis results showed that ITLN1, TSPAN11, CXCL13, and GPRC5B were downregulated and TIMP1 was upregulated in most tumor samples, including COAD, which was consistent with the results of the TCGA and GEO cohorts. Western blot analysis and immunohistochemistry were performed to validate protein expression. Tumor immune infiltration analysis results showed that TSPAN11, GPRC5B, TIMP1, and CXCL13 protein levels were significantly positively correlated with CD4+ T cells, macrophages, neutrophils, and dendritic cells. Further, the TIMP1 and CXCL13 proteins were significantly related to the tumor immune infiltration of CD8+ T cells. We recommend using our signature as a molecular prognostic classifier to assess the prognostic risk of patients with COAD. Show less

RNA editing is a feature of RNA maturation resulting in the formation of transcripts whose sequence differs from the genome template. Brain RNA editing may be altered in Alzheimer's disease (AD). Here, we analyzed data from 1,865 brain samples covering 9 brain regions from 1,074 unrelated subjects on a transcriptome-wide scale to identify inter-regional differences in RNA editing. We expand the list of known brain editing events by identifying 58,761 previously unreported events. We note that only a small proportion of these editing events are found at the protein level in our proteome-wide validation effort. We also identified the occurrence of editing events associated with AD dementia, neuropathological measures and longitudinal cognitive decline in: SYT11, MCUR1, SOD2, ORAI2, HSDL2, PFKP, and GPRC5B. Thus, we present an extended reference set of brain RNA editing events, identify a subset that are found to be expressed at the protein level, and extend the narrative of transcriptomic perturbation in AD to RNA editing. Show less

Megalencephalic Leukoencephalopathy with subcortical Cysts (MLC) is a type of vacuolating leukodystrophy, which is mainly caused by mutations in MLC1 or GLIALCAM. The two MLC-causing genes encode for membrane proteins of yet unknown function that have been linked to the regulation of different chloride channels such as the ClC-2 and VRAC. To gain insight into the role of MLC proteins, we have determined the brain GlialCAM interacting proteome. The proteome includes different transporters and ion channels known to be involved in the regulation of brain homeostasis, proteins related to adhesion or signaling as several G protein-coupled receptors (GPCRs), including the orphan GPRC5B and the proposed prosaposin receptor GPR37L1. Focusing on these two GPCRs, we could validate that they interact directly with MLC proteins. The inactivation of Gpr37l1 in mice upregulated MLC proteins without altering their localization. Conversely, a reduction of GPRC5B levels in primary astrocytes downregulated MLC proteins, leading to an impaired activation of ClC-2 and VRAC. The interaction between the GPCRs and MLC1 was dynamically regulated upon changes in the osmolarity or potassium concentration. We propose that GlialCAM and MLC1 associate with different integral membrane proteins modulating their functions and acting as a recruitment site for various signaling components as the GPCRs identified here. We hypothesized that the GlialCAM/MLC1 complex is working as an adhesion molecule coupled to a tetraspanin-like molecule performing regulatory effects through direct binding or influencing signal transduction events. Show less

Despite recent advance in immune therapy, great heterogeneity exists in the outcomes of colorectal cancer (CRC) patients. In this study, we aimed to analyze the immune-related gene (IRG) expression profiles from three independent public databases and develop an effective signature to forecast patient's prognosis. IRGs were collected from the ImmPort database. The CRC dataset from The Cancer Genome Atlas (TCGA) database was used to identify a prognostic gene signature, which was verified in another two CRC datasets from the Gene Expression Omnibus (GEO). Gene function enrichment analysis was conducted. A prognostic nomogram was built incorporating the IRG signature with clinical risk factors. The three datasets had 487, 579, and 224 patients, respectively. A prognostic six-gene-signature (CCL22, LIMK1, MAPKAPK3, FLOT1, GPRC5B, and IL20RB) was developed through feature selection that showed good differentiation between the low- and high-risk groups in the training set ( The immune-related six-gene signature is a reliable prognostic indicator for CRC patients and could provide insight for personalized cancer management. Show less

In the past decade, physiological roles and molecular functions of GPRC5 family receptors, originally identified as retinoic acid-induced gene products, have been uncovered, even though their intrinsic agonists are still a mystery. They are differentially distributed in certain tissues and cells in the body suggesting that cell-type-specific regulations and functions are significant. Molecular biological approaches and knockout mouse studies reveal that GPRC5 family proteins have pivotal roles in cancer progression and control of metabolic homeostasis pathways. Remarkably, GPRC5B-mediated tyrosine-phosphorylation signalling cascades play a critical role in development of obesity and insulin resistance through dynamic sphingolipid metabolism. Show less

G protein-coupled receptors are important regulators of contractility and differentiation in vascular smooth muscle cells (SMCs), but the specific function of SMC-expressed orphan G protein-coupled receptor class C group 5 member B (GPRC5B) is unclear. We studied the role of GPRC5B in the regulation of contractility and dedifferentiation in human and murine SMCs in vitro and in iSM- Mesenteric arteries from SMC-specific Taken together, our data show that GPRC5B regulates vascular SMC tone and differentiation by negatively regulating IP signaling. Show less

The extremely high proliferation rate of tumor cells contributes to pancreatic cancer (PC) progression. Runt-related transcription factor 1(RUNX1), a key factor in hematopoiesis that was correlated with tumor progression. However, the role of RUNX1 in PC proliferation was still unclear. We found that RUNX1 was significantly upregulated in PC tissues and its expression was negatively associated with prognosis of PC patients in a multicenter analysis according to immunohistochemical (IHC). RUNX1 downregulation in PC resulted in a significantly reduced cell proliferation rate, which was consistent with in vivo subcutaneous tumor formation assay results. RNA-seq and ChIP-seq results revealed that a portion of target genes, including HAP1, GPRC5B, PTPN21, VHL and EN2, were regulated by RUNX1, a finding successfully validated by ChIP-qPCR, qRT-PCR and Western blot. Subsequently, IHC and proliferation assays showed these target genes to be dysregulated in PC, affecting tumor growth. Our data suggest that RUNX1 plays an oncogenic role in tumor proliferation and is a potential prognostic biomarker and therapeutic target for PC. Show less

G protein coupled receptors (GPCRs) are the main mediators of signal transduction in the central nervous system. Therefore, it is not surprising that many GPCRs have long been investigated for their role in the development of anxiety and mood disorders, as well as in the mechanism of action of antidepressant therapies. Importantly, the endogenous ligands for a large group of GPCRs have not yet been identified and are therefore known as orphan GPCRs (oGPCRs). Nonetheless, growing evidence from animal studies, together with genome wide association studies (GWAS) and post-mortem transcriptomic analysis in patients, pointed at many oGPCRs as potential pharmacological targets. Among these discoveries, we summarize in this review how emotional behaviors are modulated by the following oGPCRs: ADGRB2 (BAI2), ADGRG1 (GPR56), GPR3, GPR26, GPR37, GPR50, GPR52, GPR61, GPR62, GPR88, GPR135, GPR158, and GPRC5B. Show less

Triple-negative breast cancer is categorized by a lack of hormone receptors, inefficacy of anti-estrogen or aromatase inhibitor chemotherapies and greater mortality rates in African American populations. Advanced-stage breast tumors have a high concentration of tumor necrosis factor-α (TNFα) throughout the tumor/stroma milieu, prompting sustained release of diverse chemokines (i.e. C-C motif chemokine ligand 2 (CCL2)/CCL5). These potent chemokines can subsequently direct mass infiltration of leukocyte sub-populations to lodge within the tumor, triggering a loss of tumor immune surveillance and subsequent rapid tumor growth. Previously, we demonstrated that in the MDA-MB-231 TNBC cell line, TNFα evoked a rise in immune signaling proteins: CCL2, granulocyte macrophage colony-stimulating factor, interleukin (IL)1α, IL6 and inhibitor of nuclear factor kappa-B kinase subunit epsilon (IKBKε) all of which were attenuated by apigenin, a dietary flavonoid found in chamomile and parsley. The present work elucidates changes evoked by TNFα in the presence or absence of apigenin by examining the entire transcriptome for mRNA and long intergenic non-coding RNA with Affymetrix Hugene-2.1_ST human microarrays. Differential gene-expression analysis was conducted on 48,226 genes. TNFα caused up-regulation of 75 genes and down-regulation of 10. Of these, apigenin effectively down-regulated 35 of the 75 genes which were up-regulated by TNFα. These findings confirm our previous work, specifically for the TNFα-evoked spike in IL1A vs. untreated controls [+21-fold change (FC), p<0.0001] being attenuated by apigenin in the presence of TNFa (-15 FC vs. TNFα, p<0.0001). Similar trends were seen for apigenin-mediated down-regulation of TNFα-up-regulated transcripts: IKBKE (TNFα: 4.55 FC vs. control, p<0.001; and TNFα plus apigenin: -4.92 FC, p<0.001), CCL2 (2.19 FC, p<0.002; and -2.12 FC, p<0.003), IL6 (3.25 FC, p<0.020; and -2.85 FC, p<0.043) and CSF2 (TNFα +6.04 FC, p<0.001; and -2.36 FC, p<0.007). In addition, these data further establish more than a 65% reduction by apigenin for the following transcripts which were also up-regulated by TNFα: cathepsin S (CTSS), complement C3 (C3), laminin subunit gamma 2 (LAMC2), (TLR2), toll-like receptor 2 G protein-coupled receptor class C group 5 member B (GPRC5B), contactin-associated protein 1 (CNTNAP1), claudin 1 (CLDN1), nuclear factor of activated T-cells 2 (NFATC2), C-X-C motif chemokine ligand 10 (CXCL10), CXCL11, interleukin 1 receptor-associated kinase 3 (IRAK3), nuclear receptor subfamily 3 group C member 2 (NR3C2), interleukin 32 (IL32), IL24, slit guidance ligand 2 (SLIT2), transmembrane protein 132A (TMEM132A), TMEM171, signal transducing adaptor family member 2 (STAP2), mixed lineage kinase domain-like pseudokinase (MLKL), kinase insert domain receptor (KDR), BMP-binding endothelial regulator (BMPER), and kelch-like family member 36 (KLHL36). There is a possible therapeutic role for apigenin in down-regulating diverse genes associated with tumorigenic leukocyte sub-population infiltration by triple-negative breast cancer. The data have been deposited into the Gene Expression Omnibus for public analysis at https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE120550. Show less

Inflammatory processes play an important role in the pathogenesis of glomerulopathies. Finding novel ways to suppress glomerular inflammation may offer a new way to stop disease progression. However, the molecular mechanisms that initiate and drive inflammation in the glomerulus are still poorly understood. We performed large-scale gene expression profiling of glomerulus-associated G protein-coupled receptors (GPCRs) to identify new potential therapeutic targets for glomerulopathies. The expression of Gprc5b in disease was analyzed using quantitative PCR and immunofluorescence, and by analyzing published microarray data sets. We identified an orphan GPCR, Gprc5b, as a novel gene highly enriched in podocytes that was significantly upregulated in common human glomerulopathies, including diabetic nephropathy, IgA nephropathy, and lupus nephritis. Similar upregulation of Gprc5b was detected in LPS-induced nephropathy in mice. Studies in podocyte-specific Gprc5b knockout mice showed that Gprc5b was not essential for normal development of the glomerular filtration barrier. However, knockout mice were partially protected from LPS-induced proteinuria and recruitment of inflammatory cells. Mechanistically, RNA sequencing in Gprc5b knockouts mice and experiments in cultured human podocytes showed that Gpr5cb regulated inflammatory response in podocytes GPRC5b is a novel podocyte-specific receptor that regulates inflammatory response in the glomerulus by modulating the NF- Show less

Exosomes, vehicles for intercellular communication, are formed intracellularly within multivesicular bodies (MVBs) and are released upon fusion with the plasma membrane. For their biogenesis, proper cargo loading to exosomes and vesicle traffic for extracellular release are required. Previously we showed that the L-type lectin, LMAN2, limits trans-Golgi Network (TGN)-to-endosomes traffic of GPRC5B, an exosome cargo protein, for exosome release. Here, we identified that the protein deacetylase sirtuin 2 (SIRT2) as a novel interactor of LMAN2. Loss of SIRT2 expression resulted in exosomal release of LMAN2, a Golgi resident protein, along with increased exosomal release of GPRC5B. Furthermore, knockout of SIRT2 increased total number of extracellular vesicles (EVs), indicating increased MVB-to-EV flux. While knockout of SIRT1 increased EV release with enlarged late endolysosome, knockout of SIRT2 did not exhibit endolysosome enlargement for increased EV release. Taken together, our study suggests that SIRT2 regulates cargo loading to MVBs and MVB-to-EV flux through a mechanism distinct from that of SIRT1. Show less

Inflammation is a major driver of cardiac remodeling. Cardiac fibroblasts play an integral role in cardiac inflammation, fibrosis and remodeling. The orphan G-protein-coupled-receptor 5B of family C (GPRC5B) has recently been shown to have pro-inflammatory effects in adipocytes via the NFκB-signaling-pathway. Here, we investigated whether GPRC5B is involved in myocardial inflammation and fibrosis. Using neonatal rat cardiac fibroblasts (NRCF) we show that the transcription and the expression of endogenous GPRC5B is induced by stimulation with TNFα and LPS as well as through cyclic mechanical stretch, while the principle pro-fibrotic factor TGFβ has no effect on the GPRC5B expression. Furthermore, we demonstrate that adenoviral overexpression and siRNA-mediated knockdown of GPRC5B in NRCF significantly alters the transcription level of the pro-inflammatory and pro-fibrotic cytokines TNFα, IL-1β, IL-6 and MCP-1, and extracellular matrix-degrading MMP-9 in vitro. Additionally, in adult GPRC5B-transgenic mice the protein expression of collagen-1A1 is decreased and the production of MMP-9 is increased, indicating remodeling of the extracellular matrix in vivo. Our data show that GPRC5B is up-regulated by inflammatory signals and mechanical stress in NRCF, while GPRC5B modulates the inflammatory response of cardiac fibroblasts and the degradation of extracellular matrix-proteins in the mice heart. Thus, our findings are the first to report a novel role of the orphan receptor GPRC5B in fibroblast-driven myocardial inflammation and cardiac remodeling. Show less

Alopecia or hair loss is a complex polygenetic and psychologically devastating disease affecting millions of men and women globally. Since the gene annotation and environmental knowledge is limited for alopecia, a systematic analysis for the identification of candidate biomarkers is required that could provide potential therapeutic targets for hair loss therapy. We designed an interactive framework to perform a meta-analytical study based on differential expression analysis, systems biology, and functional proteomic investigations. We analyzed eight publicly available microarray datasets and found 12 potential candidate biomarkers including three extracellular proteins from the list of differentially expressed genes with a Our integrative approach helps to prioritize the biomarkers that ultimately lessen the economic burden of experimental studies. It will also be valuable to discover mutants in genomic data in order to increase the identification of new biomarkers for similar problems. Show less

Obesity during childhood can lead to increased risk of adverse cardiometabolic diseases such as type 2 diabetes and coronary artery disease during adult life. Evidence for strong genetic correlations between child and adult body mass index (BMI) suggest the possibility of shared genetic effects. We performed a test for pleiotropy (shared genetics) and functional enrichment of single nucleotide polymorphisms (SNPs) associated with childhood BMI and 15 adult cardiometabolic traits using a unified statistical approach that integrates pleiotropy and functional annotation data. Pleiotropic genetic effects were significantly abundant in 13 out of 15 childhood BMI-adult cardiometabolic trait tests (P < 3.3 × 10 This study found significant pleiotropic genetic effects and enrichment of functional annotations in genetic variants that were jointly associated with childhood obesity and adult cardiometabolic diseases. The findings provide new avenues to disentangle the genetic basis of life course associations between childhood obesity and adult cardiometabolic diseases. Show less

GPRC5B recruitment of Src family kinases has been implicated in diet-induced insulin resistance. However, the mechanism of this action is not fully understood. Here, we report that GPRC5B-mediated phosphorylation of sphingomyelin synthase 2 (SMS2) by Fyn is a crucial step in the development of insulin resistance. Lipid-induced metabolic stress augments SMS2 phosphorylation by facilitating the interaction of GPRC5B and SMS2. SMS2 phosphorylation reduces its ubiquitination, and consequently increases SMS2 protein abundance. Although ceramide and diacylglycerol (DAG) have been known to be central mediators of lipid-induced insulin resistance, the accumulation of these lipids fails to impair insulin signaling in SMS2 knockout mouse embryonic fibroblasts (MEFs). Conversely, exogenous expression of a phosphomimetic SMS2 impairs insulin action in SMS2 knockout MEFs under metabolic stress conditions. We demonstrate that SMS2-generated DAG in sphingomyelin synthesis inhibits insulin signaling through JNK activation. Thus, GPRC5B links sphingolipid metabolism to diet-induced insulin resistance via SMS2-dependent DAG production. Show less

Tyrosine phosphorylation of GPRC5B and phosphorylation-dependent recruitment of Fyn through the SH2 domain have been implicated in NF-κB activation and obesity-linked adipose inflammation. GPRC5B tightly associates with caveolin-1 (Cav1); however, the role of this interaction remains elusive. Here, we report that Cav1 reduces GPRC5B-mediated NF-κB signaling by blocking GPRC5B-phosphorylation. We demonstrate highly abundant tyrosine phosphorylation of GPRC5B is observed in Neuro2a cells lacking endogenous Cav1 expression. Reversely, exogenous expression of Cav1 in these cells inhibits GPRC5B-phosphorylation. Although GPRC5B lacks conventional caveolin-binding motif, cytoplasmic tail of GPRC5B directly interacts with the C-terminal domain of Cav1. The vacant scaffolding domain of Cav1 in the protein complex suggests a potential mechanism for blocking GPRC5B-phosphorylation by Cav1, because Fyn loses the activity by binding with Cav1-scaffolding domain. Enhanced GPRC5B-mediated NF-κB signaling in Cav1-deficient cells were observed under palmitate-induced metabolic stress. These results support Cav1 functions as a negative modulator for GPRC5B action. Show less

Current bovine pregnancy detection methods are not reliable until at least day 28 post artificial insemination (AI). The bovine estrous cycle is approximately 21 days; consequently, producers miss an opportunity to rebreed at the next estrous event. Therefore, commercial interest exists for the discovery of novel biomarkers of pregnancy which could reliably detect pregnancy status at or before day 21 of pregnancy. The objective of the present study was to use liquid chromatography tandem mass spectrometry (LC-MS/MS) to perform a global, label-free, proteomics study on (i) milk whey and (ii) extracellular vesicle (EV) enriched milk whey samples, from day 21 of pregnancy, compared with day 21 of the estrous cycle, in order to identify potential protein biomarkers of early pregnancy. The estrous cycles of 10 dairy cows were synchronized, they went through one (control) estrous cycle and these cows were artificially inseminated during the following estrus. These cows were confirmed pregnant by ultrasound scanning. Milk whey samples were collected on day 21 of the estrous cycle and on day 21 post AI. Milk whey samples and EV enriched milk whey samples were analyzed by LC-MS/MS and subsequent analyzes of the label-free quantitative data was performed in MaxQuant and Perseus. Four proteins (APOB, SPADH1, PLIN2 and LPO) were differentially expressed between the proteomes of milk whey from day 21 of pregnancy and day 21 of the estrous cycle (P < 0.05). Ten proteins (PIGR, PGD, QSOX1, MUC1, SRPRA, MD2, GAPDH, FOLR1, GPRC5B and HHIPL2) were differentially expressed between the proteomes of EV enriched milk whey from day 21 of pregnancy and day 21 of the estrous cycle (P < 0.05). These proteins are potential milk whey biomarkers of early pregnancy. Show less

CRISPR-Cas9, a RNA-guided targeted genome editing tool, has revolutionized genetic engineering by offering the ability to precisely modify DNA. GPRC5B is an orphan receptor belonging to the group C family of G protein-coupled receptors (GPCRs). In this study, we analysed the functional roles of the Gprc5b receptor in MIN6 β-cells using CRISPR-Cas9 and transient over-expression of Gprc5b. The optimal transfection reagent for use in MIN6 β-cells was determined by analysing efficiency of GFP plasmid delivery by cell sorting. A MIN6 β-cell line in which Gprc5b expression was knocked down (Gprc5b KD) was generated using CRISPR-Cas9 technology. Gprc5b receptor mRNA expression, proliferation, apoptosis, Cignal 45-Pathway Reporter Array signalling and western blot assays were carried out using Gpcr5b KD MIN6 β-cells that had been transiently transfected with different concentrations of mouse Gprc5b plasmid to over-express Gprc5b. JetPRIME® was the best candidate for MIN6 β-cell transfection, providing approximately 30% transfection efficiency. CRISPR-Cas9 technology targeting Gprc5b led to stable knock-down of this receptor in MIN6 β-cells and its re-expression induced proliferation and potentiated cytokine- and palmitate-induced apoptosis. The Cignal 45 Reporter analysis indicated Gprc5b-dependent regulation of apoptotic and proliferative pathways, and western blotting confirmed activation of signalling via TGF-β and IFNγ. This study provides evidence of CRISPR-Cas9 technology being used to down-regulate Gprc5b expression in MIN6 β-cells. This strategy allowed us to identify signalling pathways linking GPRC5B receptor expression to β-cell proliferation and apoptosis. Show less

Syntaxin 3 (Stx3), a SNARE protein located and functioning at the apical plasma membrane of epithelial cells, is required for epithelial polarity. A fraction of Stx3 is localized to late endosomes/lysosomes, although how it traffics there and its function in these organelles is unknown. Here we report that Stx3 undergoes monoubiquitination in a conserved polybasic domain. Stx3 present at the basolateral-but not the apical-plasma membrane is rapidly endocytosed, targeted to endosomes, internalized into intraluminal vesicles (ILVs), and excreted in exosomes. A nonubiquitinatable mutant of Stx3 (Stx3-5R) fails to enter this pathway and leads to the inability of the apical exosomal cargo protein GPRC5B to enter the ILV/exosomal pathway. This suggests that ubiquitination of Stx3 leads to removal from the basolateral membrane to achieve apical polarity, that Stx3 plays a role in the recruitment of cargo to exosomes, and that the Stx3-5R mutant acts as a dominant-negative inhibitor. Human cytomegalovirus (HCMV) acquires its membrane in an intracellular compartment and we show that Stx3-5R strongly reduces the number of excreted infectious viral particles. Altogether these results suggest that Stx3 functions in the transport of specific proteins to apical exosomes and that HCMV exploits this pathway for virion excretion. Show less

G-protein-coupled receptor (GPCR) expression is extensively studied in bulk cDNA, but heterogeneity and functional patterning of GPCR expression in individual vascular cells is poorly understood. Here, we perform a microfluidic-based single-cell GPCR expression analysis in primary smooth muscle cells (SMC) and endothelial cells (EC). GPCR expression is highly heterogeneous in all cell types, which is confirmed in reporter mice, on the protein level and in human cells. Inflammatory activation in murine models of sepsis or atherosclerosis results in characteristic changes in the GPCR repertoire, and we identify functionally relevant subgroups of cells that are characterized by specific GPCR patterns. We further show that dedifferentiating SMC upregulate GPCRs such as Gpr39, Gprc5b, Gprc5c or Gpr124, and that selective targeting of Gprc5b modulates their differentiation state. Taken together, single-cell profiling identifies receptors expressed on pathologically relevant subpopulations and provides a basis for the development of new therapeutic strategies in vascular diseases. Show less