The role of GPR56/ADGRG1 in health and disease

Comparative RNA-Seq analysis of differentially expressed genes in the sertoli cells of yak and cattle-yak

BACKGROUND

To study the problem of male sterility of cattle-yak and improve the yak crossbreeding, this study obtained the testicular Sertoli cells of yak and cattle-yak and compared the differences in transcriptome levels between the two bovine species. The testicular tissues of 3 healthy male cattle-yaks and 3 F1 generation male yaks were collected at the age of 24 months. The Sertoli cells were isolated after enzymatic digestion, differential adhesion and starvation treatment. DATA-4 and SOX9 immunofluorescence staining were used to identify the cell type. Sertoli cells were subjected to transcriptome sequencing, GO analysis, KEGG analysis and differentially expressed gene were validated by RT-qPCR and Western blotting.

RESULTS

The study successfully isolated and purified Sertoli cells of yak and cattle-yak. The transcriptome sequencing data were compared, analyzed and annotated. Compared to yak Sertoli cells, 6592 differentially expressed genes were identified, with 3007 genes upregulated and 3585 genes downregulated in cattle-yak Sertoli cells. GO analysis suggested that the upregulated genes might be mainly involved in processes such as translation, peptide biosynthetic process, amide biosynthetic process, peptide metabolic process, ribosome, cytoplasmic part, structural constituent of ribosome, structural molecule activity, endomembrane system, protein kinase activity, and phosphotransferase activity. The downregulated genes appeared to be primarily involved in protein phosphorylation, phosphorylation, endomembrane system, protein kinase activity, and phosphotransferase activity. KEGG analysis compared differential genes across 316 pathways, with 8 pathways showing significant enrichment. The upregulated pathways were potentially enriched in cattle-yak Sertoli cells, including ribosome, thermogenesis, and oxidative phosphorylation, while the downregulated pathways seemed to be significantly enriched in adherens junction, mTOR signaling pathway, AMPK signaling pathway, FoxO signaling pathway, and focal adhesion. Compared with yak Sertoli cells, ISOC2, RPL27A and FISI were highly expressed in cattle-yak, as confirmed by RT-qPCR analysis. PDPN, SORBS2, TF, PLSCR1, TJP2, KIF2C, ITGA3, SMTNL2, DSP, ADGRG1, DDR1, GSK3A, RBBP6, ZC3H15 and Claudin 11 showed low expression levels in cattle-yak.

CONCLUSIONS

Compared with yak Sertoli cells, the expression of genes related to protein activation, cell function, and membranous organelle composition in cattle-yak Sertoli cells appeared to be abnormal. The potential defects in cattle-yak Sertoli cells may hinder the creation of a suitable environment for spermatogenesis, which could be one of the factors contributing to male cattle-yak sterility. Claudin-11 might be a potentially important gene for further research into cattle-yak male sterility.

Identification of biomarkers for tumor regression grade in esophageal squamous cell carcinoma patients after neoadjuvant chemoradiotherapy

Background

Esophageal cancer is a highly invasive malignancy. Neoadjuvant chemoradiotherapy not only increases the rate of complete resection but also improves the median survival. However, a sensitive biomarker is urgently needed in clinical practice.

Methods

60 esophageal squamous cell carcinoma (ESCC) patients undergoing neoadjuvant chemoradiotherapy (NCRT) were enrolled at the People's Hospital Affiliated to Jiangsu University. Patients were grouped according to tumor regression grade (TRG) criteria from the College of American Pathologists (CAP). The correlation between TRG groups, clinicopathologic characteristics, and prognosis was analyzed. Differential gene expression analysis was performed on ESCC patients before and after NCRT using the public database (GSE43519). MMP9, NFIX, and GPR56 were identified as candidate genes, and their expression and correlation with prognosis were evaluated by immunohistochemical analysis.

Results

Among 60 ESCC patients who underwent surgery after NCRT, the pathological complete response (pCR) rate was 35.0% (21/60), and the major pathological response (MPR) rate was 60.0% (36/60). Poor tumor differentiation and neural or vascular invasion were associated with inadequate tumor regression grade and were independent factors influencing TRG. ESCC patients were divided into effective (TRG 0 + 1) and ineffective (TRG 2 + 3) groups. Higher TRG was significantly associated with shorter overall survival (OS). Our study also identified TRG as an independent prognostic factor through univariate and multivariate Cox regression analyses (P < 0.05). The differentially expressed genes GPR56, MMP9, and NFIX selected from the GSE43519 dataset were significantly downregulated after NCRT (P < 0.001). Immunohistochemistry showed that GPR56 was highly expressed in ESCC, while it was negatively expressed in paracancerous tissues. There was a significant difference in expression between cancerous and paracancerous tissues. GPR56 expression was consistent with the public dataset, and patients with high GPR56 expression had significantly shorter OS (P < 0.05). In addition, patients with inadequate MPR and high GPR56 expression had shorter OS (P < 0.05).

Conclusions

The findings suggest that TRG serves as an independent prognostic factor for ESCC following NCRT. High GPR56 expression is found to be associated with a poor prognosis of ESCC. Downregulation of GPR56 suggests a potential significant predictive value in conjunction with MPR analysis.

Characterization of Freshly Isolated Human Peripheral Blood B Cells, Monocytes, CD4+ and CD8+ T Cells, and Skin Mast Cells by Quantitative Transcriptomics

Quantitative transcriptomics offers a new way to obtain a detailed picture of freshly isolated cells. By direct isolation, the cells are unaffected by in vitro culture, and the isolation at cold temperatures maintains the cells relatively unaltered in phenotype by avoiding activation through receptor cross-linking or plastic adherence. Simultaneous analysis of several cell types provides the opportunity to obtain detailed pictures of transcriptomic differences between them. Here, we present such an analysis focusing on four human blood cell populations and compare those to isolated human skin mast cells. Pure CD19+ peripheral blood B cells, CD14+ monocytes, and CD4+ and CD8+ T cells were obtained by fluorescence-activated cell sorting, and KIT+ human connective tissue mast cells (MCs) were purified by MACS sorting from healthy skin. Detailed information concerning expression levels of the different granule proteases, protease inhibitors, Fc receptors, other receptors, transcription factors, cell signaling components, cytoskeletal proteins, and many other protein families relevant to the functions of these cells were obtained and comprehensively discussed. The MC granule proteases were found exclusively in the MC samples, and the T-cell granzymes in the T cells, of which several were present in both CD4+ and CD8+ T cells. High levels of CD4 were also observed in MCs and monocytes. We found a large variation between the different cell populations in the expression of Fc receptors, as well as for lipid mediators, proteoglycan synthesis enzymes, cytokines, cytokine receptors, and transcription factors. This detailed quantitative comparative analysis of more than 780 proteins of importance for the function of these populations can now serve as a good reference material for research into how these entities shape the role of these cells in immunity and tissue homeostasis.

Circulating CD8 + LGALS9 + T Cell Population Exhibiting Low Cytotoxic Characteristics are Decreased in Patients with Systemic Lupus Erythematosus

LGALS9, also known as Galectin-9 and a member of the β-galactosidase family, plays a crucial role in immune regulation. However, its expression and function in CD8 T cells, as well as its association with cytotoxic T lymphocytes (CTL), remain unclear. This study aims to investigate LGALS9 expression patterns in human circulating CD8 T lymphocytes and elucidate its clinical significance in Systemic Lupus Erythematosus (SLE). Blood samples from 56 healthy controls and 50 new-onset SLE patients were collected. Flow cytometry was utilized to analyze LGALS9 expression in circulating CD8 T lymphocytes via intracellular staining. Compared to LGALS9 + CD8 + T cells, LGALS9-CD8 + T cells showed increased secretion of Granzyme B (GZMB) and Perforin, along with elevated expression levels of GPR56, CX3CR1, KLRD1, KLRF1, PD1, and CD29. A higher proportion of Tn (naive T cells) and TCM (central memory T cells) showed LGALS9 positivity, compared to TEM (effector memory T cells) and TEMRA (terminally differentiated effector memory T cells re-expressing CD45RA). Clinically, the downregulation of LGALS9 expression was significant in SLE patients. LGALS9 + CD8 + T cells exhibited an Area Under the Curve (AUC) of 0.6916, while CX3CR1 + in LGALS9 + CD8 + T cells had an AUC of 0.6478, and KLRF1 + had an AUC of 0.6419, for distinguishing SLE from healthy individuals. In conclusion, CD8 + LGALS9 + T cells display characteristics of low cytotoxicity, and their reduction is evident in SLE patients, potentially implicating them in SLE pathogenesis and providing diagnostic assistance.

GPR56 facilitates hepatocellular carcinoma metastasis by promoting the TGF-β signaling pathway

The metastasis of hepatocellular carcinoma (HCC) poses a significant threat to the survival of patients. G protein-coupled receptor 56 (GPR56) has garnered extensive attention within malignant tumor research and plays a crucial role in cellular surface signal transmission. Nonetheless, its precise function in HCC remains ambiguous. Our investigation reveals a notable rise in GPR56 expression levels in human HCC cases, with heightened GPR56 levels correlating with unfavorable prognoses. GPR56 regulates TGF-β pathway by interacting with TGFBR1, thereby promoting HCC metastasis. At the same time, GPR56 is subject to regulation by the canonical cascade of TGF-β signaling, thereby establishing a positive feedback loop. Furthermore, the combination application of TGFBR1 inhibitor galunisertib (GAL) and GPR56 inhibitor Dihydromunduletone (DHM), significantly inhibits HCC metastasis. Interventions towards this signaling pathway could offer a promising therapeutic approach to effectively impede the metastasis of GPR56-mediated HCC.

GPR56: A potential therapeutic target for neurological and psychiatric disorders

GPR56, also known as GPR56/ADGRG1, is a member of the ADGRG subgroup belonging to adhesion G protein-coupled receptors (aGPCRs). aGPCRs are the second largest subfamily of the GPCR superfamily, which is the largest family of membrane protein receptors in the human genome. Studies in recent years have demonstrated that GPR56 is integral to the normal development of the brain and functions as an important player in cortical development, suggesting that GPR56 is involved in many physiological processes. Indeed, aberrant expression of GPR56 has been implicated in multiple neurological and psychiatric disorders, including bilateral frontoparietal polymicrogyria (BFPP), depression and epilepsy. In a recent study, it was found that upregulated expression of GPR56 reduced depressive-like behaviours in an animal model of depression, indicating that GPR56 plays an important role in the antidepressant response. Given the link of GPR56 with the antidepressant response, the function of GPR56 has become a focus of research. Although GPR56 may be a potential target for the development of antidepressants, the underlying molecular mechanisms remain largely unknown. Therefore, in this review, we will summarize the latest findings of GPR56 function in neurological and psychiatric disorders (depression, epilepsy, autism, and BFPP) and emphasize the mechanisms of GPR56 in activation and signalling in those conditions. After reviewing several studies, attributing to its significant biological functions and exceptionally long extracellular N-terminus that interacts with multiple ligands, we draw a conclusion that GPR56 may serve as an important drug target for neuropsychological diseases.

Differential GPR56 Expression in T Cell Subpopulations for Early-Stage Lung Adenocarcinoma Patient Identification

OBJECTIVE

This study aimed to investigate the expression of GPR56 in the T cells of early-stage lung adenocarcinoma (LUAD) patients and clarify its diagnostic significance.

METHODS

Blood samples were collected from 32 patients with stage IA LUAD and 31 healthy controls. GPR56 and perforin were analysed in circulating T-cell subsets by flow cytometry. In addition, a correlation between perforin and GPR56 expression was detected. Changes in GPR56+ cells in early LUAD patients were analysed, and the diagnostic significance of GPR56+ T cells for early LUAD was studied by receiver operating characteristic (ROC) curve analysis.

RESULTS

The expression of GPR56 in CD8+ T cells from early-stage LUAD patients was significantly greater than that in CD4+ T cells. The percentage of perforin-positive GPR56+ cells in early-stage LUAD patients was high. GPR56 levels in the T cells of LUAD patients were significantly lower than those in healthy controls. ROC analysis revealed that the area under the curve for the percentage of GPR56-positive CD8+ TEMRA cells to distinguish early-stage LUAD patients from healthy individuals- reached 0.7978.

CONCLUSION

The decreased expression of GPR56 in the peripheral blood of early-stage LUAD patients correlated with perforin levels, reflecting compromised antitumor immunity and aiding early-stage LUAD screening.

Data-Driven and Cell-Specific Determination of Nuclei-Associated Actin Structure

Quantitative and volumetric assessment of filamentous actin fibers (F-actin) remains challenging due to their interconnected nature, leading researchers to utilize threshold based or qualitative measurement methods with poor reproducibility. Here we introduce a novel machine learning based methodology for accurate quantification and reconstruction of nuclei-associated F-actin. Utilizing a Convolutional Neural Network (CNN), we segment actin filaments and nuclei from 3D confocal microscopy images and then reconstruct each fiber by connecting intersecting contours on cross-sectional slices. This allowed measurement of the total number of actin filaments and individual actin filament length and volume in a reproducible fashion. Focusing on the role of F-actin in supporting nucleocytoskeletal connectivity, we quantified apical F-actin, basal F-actin, and nuclear architecture in mesenchymal stem cells (MSCs) following the disruption of the Linker of Nucleoskeleton and Cytoskeleton (LINC) Complexes. Disabling LINC in mesenchymal stem cells (MSCs) generated F-actin disorganization at the nuclear envelope characterized by shorter length and volume of actin fibers contributing a less elongated nuclear shape. Our findings not only present a new tool for mechanobiology but introduce a novel pipeline for developing realistic computational models based on quantitative measures of F-actin.

Integrating Genome Sequencing and Untargeted Metabolomics in Monozygotic Twins with a Rare Complex Neurological Disorder

Multi-omics approaches, which integrate genomics, transcriptomics, proteomics, and metabolomics, have emerged as powerful tools in the diagnosis of rare diseases. We used untargeted metabolomics and whole-genome sequencing (WGS) to gain a more comprehensive understanding of a rare disease with a complex presentation affecting female twins from a consanguineous family. The sisters presented with polymicrogyria, a Dandy-Walker malformation, respiratory distress, and multiorgan dysfunctions. Through WGS, we identified two rare homozygous variants in both subjects, a pathogenic variant in ADGRG1(p.Arg565Trp) and a novel variant in CNTNAP1(p.Glu910Val). These genes have been previously associated with autosomal recessive polymicrogyria and hypomyelinating neuropathy with/without contractures, respectively. The twins exhibited symptoms that overlapped with both of these conditions. The results of the untargeted metabolomics analysis revealed significant metabolic perturbations relating to neurodevelopmental abnormalities, kidney dysfunction, and microbiome. The significant metabolites belong to essential pathways such as lipids and amino acid metabolism. The identification of variants in two genes, combined with the support of metabolic perturbation, demonstrates the rarity and complexity of this phenotype and provides valuable insights into its underlying mechanisms.

Former smoking associated with epigenetic modifications in human granulosa cells among women undergoing assisted reproduction

Smoking exposure during adulthood can disrupt oocyte development in women, contributing to infertility and possibly adverse birth outcomes. Some of these effects may be reflected in epigenome profiles in granulosa cells (GCs) in human follicular fluid. We compared the epigenetic modifications throughout the genome in GCs from women who were former (N = 15) versus never smokers (N = 44) undergoing assisted reproductive technologies (ART). This study included 59 women undergoing ART. Smoking history including time since quitting was determined by questionnaire. GCs were collected during oocyte retrieval and DNA methylation (DNAm) levels were profiled using the Infinium MethylationEPIC BeadChip. We performed an epigenome-wide association study with robust linear models, regressing DNAm level at individual loci on smoking status, adjusting for age, ovarian stimulation protocol, and three surrogate variables. We performed differentially methylated regions (DMRs) analysis and over-representation analysis of the identified CpGs and corresponding gene set. 81 CpGs were differentially methylated among former smokers compared to never smokers (FDR < 0.05). We identified 2 significant DMRs (KCNQ1 and RHBDD2). The former smoking-associated genes were enriched in oxytocin signaling, adrenergic signaling in cardiomyocytes, platelet activation, axon guidance, and chemokine signaling pathway. These epigenetic variations have been associated with inflammatory responses, reproductive outcomes, cancer development, neurodevelopmental disorder, and cardiometabolic health. Secondarily, we examined the relationships between time since quitting and DNAm at significant CpGs. We observed three CpGs in negative associations with the length of quitting smoking (p < 0.05), which were cg04254052 (KCNIP1), cg22875371 (OGDHL), and cg27289628 (LOC148145), while one in positive association, which was cg13487862 (PLXNB1). As a pilot study, we demonstrated epigenetic modifications associated with former smoking in GCs. The study is informative to potential biological pathways underlying the documented association between smoking and female infertility and biomarker discovery for smoking-associated reproductive outcomes.

GPR56, an Adhesion GPCR with Multiple Roles in Human Diseases, Current Status and Future Perspective

Human G protein-coupled receptor 56 (GPR56) belongs to a member of the adhesion G-protein coupled receptor (aGPCR) family and widely exists in the central nervous system and various types of tumor tissues. Recent studies have shown that abnormal expression or dysfunction of GPR56 is closely associated with many physiological and pathological processes, including brain development, neuropsychiatric disorders, cardiovascular diseases and cancer progression. In addition, GPR56 has been proven to enhance the susceptibility of some antipsychotics and anticarcinogens in response to the treatment of neuropsychological diseases and cancer. Although there have been some reports about the functions of GPR56, the underlying mechanisms implicated in these diseases have not been clarified thoroughly, especially in depression and epilepsy. Therefore, in this review, we described the molecular structure and signal transduction pathway of GPR56 and carried out a comprehensive summary of GPR56's function in the development of psychiatric disorders and cancer. Our review showed that GPR56 deficiency led to depressive-like behaviors and an increase in resistance to antipsychotic treatment. In contrast, the upregulation of GPR56 contributed to tumor cell proliferation and metastasis in malignant diseases such as glioblastoma, colorectal cancer, and ovarian cancer. Moreover, we elucidated specific signaling pathways downstream of GPR56 related to the pathogenesis of these diseases. In summary, our review provides compelling arguments for an attractive therapeutic target of GPR56 in improving the therapeutic efficiency for patients suffering from psychiatric disorders and cancer.

GPR56 Promotes Diabetic Kidney Disease Through eNOS Regulation in Glomerular Endothelial Cells

Although glomerular endothelial dysfunction is well recognized as contributing to the pathogenesis of diabetic kidney disease (DKD), the molecular pathways contributing to DKD pathogenesis in glomerular endothelial cells (GECs) are only partially understood. To uncover pathways that are differentially regulated in early DKD that may contribute to disease pathogenesis, we recently conducted a transcriptomic analysis of isolated GECs from diabetic NOS3-null mice. The analysis identified several potential mediators of early DKD pathogenesis, one of which encoded an adhesion G protein-coupled receptor-56 (GPR56), also known as ADGRG1. Enhanced glomerular expression of GPR56 was observed in human diabetic kidneys, which was negatively associated with kidney function. Using cultured mouse GECs, we observed that GPR56 expression was induced with exposure to advanced glycation end products, as well as in high-glucose conditions, and its overexpression resulted in decreased phosphorylation and expression of endothelial nitric oxide synthase (eNOS). This effect on eNOS by GPR56 was mediated by coupling of Gα12/13-RhoA pathway activation and Gαi-mediated cAMP/PKA pathway inhibition. The loss of GPR56 in mice led to a significant reduction in diabetes-induced albuminuria and glomerular injury, which was associated with reduced oxidative stress and restoration of eNOS expression in GECs. These findings suggest that GPR56 promotes DKD progression mediated, in part, through enhancing glomerular endothelial injury and dysfunction.

ARTICLE HIGHLIGHTS

Re-routing GPR56 signalling using Gα12/13 G protein chimeras

Adhesion G protein-coupled receptors (aGPCRs) constitute the second largest subclass of the GPCR superfamily. Although canonical GPCRs are explored pharmacologically as drug targets, no clinically approved drugs target the aGPCR family so far. The aGPCR GPR56/ADGRG1 stands out as an especially promising target, given its direct link to the monogenetic disease bilateral frontoparietal polymicrogyria and implications in cancers. Key to understanding GPCR pharmacology has been mapping out intracellular signalling activity. Detection of GPCR signalling in the Gαs /Gαi /Gαq G protein pathways is feasible with second messenger detection systems. However, in the case of Gα12/13 -coupled receptors, like GPR56, signalling detection is more challenging due to the lack of direct second messenger generation. To overcome this challenge, we engineered a Gαq chimera to translate Gα12/13 signalling. We show the ability of the chimeric GαΔ6q12myr and GαΔ6q13myr to translate basal Gα12/13 signalling of GPR56 to a Gαq readout in transcription factor luciferase reporter systems and show that the established peptide ligands (P7 and P19) function to enhance this signal. We further demonstrate the ability to directly influence the generation of second messengers in inositol-3-phosphate assays. In the future, these chimeric G proteins could facilitate basic functional studies, drug screenings and deorphanization of other aGPCRs.

Downstream signalling of the disease-associated mutations on GPR56/ADGRG1

GPR56/ADGRG1 is an adhesion G protein-coupled receptor (GPCR) and mutations on this receptor cause cortical malformation due to the over-migration of neural progenitor cells on brain surface. At pial surface, GPR56 interacts with collagen III, induces Rho-dependent activation through Gα12/13 and inhibits the neuronal migration. In human glioma cells, GPR56 inhibits cell migration through Gαq/11 -dependent Rho pathway. GPR56-tetraspanin complex is known to couple Gαq/11 . GPR56 is an aGPCR that couples with various G proteins and signals through different downstream pathways. In this study, bilateral frontoparietal polymicrogyria (BFPP) mutants disrupting GPR56 function but remaining to be expressed on plasma membrane were used to study receptor signalling through Gα12 , Gα13 and Gα11 with BRET biosensors. GPR56 showed coupling with all three G proteins and activated heterotrimeric G protein signalling upon stimulation with Stachel peptide. However, BFPP mutants showed different signalling defects for each G protein indicative of distinct activation and signalling properties of GPR56 for Gα12 , Gα13 or Gα11 . β-arrestin recruitment was also investigated following the activation of GPR56 with Stachel peptide using BRET biosensors. N-terminally truncated GPR56 showed enhanced β-arrestin recruitment; however, neither wild-type receptor nor BFPP mutants gave any measurable recruitment upon Stachel stimulation, pointing different activation mechanisms for β-arrestin involvement.

Plasma proteomic signatures of a direct measure of insulin sensitivity in two population cohorts

AIMS/HYPOTHESIS

The euglycaemic-hyperinsulinaemic clamp (EIC) is the reference standard for the measurement of whole-body insulin sensitivity but is laborious and expensive to perform. We aimed to assess the incremental value of high-throughput plasma proteomic profiling in developing signatures correlating with the M value derived from the EIC.

METHODS

We measured 828 proteins in the fasting plasma of 966 participants from the Relationship between Insulin Sensitivity and Cardiovascular disease (RISC) study and 745 participants from the Uppsala Longitudinal Study of Adult Men (ULSAM) using a high-throughput proximity extension assay. We used the least absolute shrinkage and selection operator (LASSO) approach using clinical variables and protein measures as features. Models were tested within and across cohorts. Our primary model performance metric was the proportion of the M value variance explained (R2).

RESULTS

A standard LASSO model incorporating 53 proteins in addition to routinely available clinical variables increased the M value R2 from 0.237 (95% CI 0.178, 0.303) to 0.456 (0.372, 0.536) in RISC. A similar pattern was observed in ULSAM, in which the M value R2 increased from 0.443 (0.360, 0.530) to 0.632 (0.569, 0.698) with the addition of 61 proteins. Models trained in one cohort and tested in the other also demonstrated significant improvements in R2 despite differences in baseline cohort characteristics and clamp methodology (RISC to ULSAM: 0.491 [0.433, 0.539] for 51 proteins; ULSAM to RISC: 0.369 [0.331, 0.416] for 67 proteins). A randomised LASSO and stability selection algorithm selected only two proteins per cohort (three unique proteins), which improved R2 but to a lesser degree than in standard LASSO models: 0.352 (0.266, 0.439) in RISC and 0.495 (0.404, 0.585) in ULSAM. Reductions in improvements of R2 with randomised LASSO and stability selection were less marked in cross-cohort analyses (RISC to ULSAM R2 0.444 [0.391, 0.497]; ULSAM to RISC R2 0.348 [0.300, 0.396]). Models of proteins alone were as effective as models that included both clinical variables and proteins using either standard or randomised LASSO. The single most consistently selected protein across all analyses and models was IGF-binding protein 2.

CONCLUSIONS/INTERPRETATION

A plasma proteomic signature identified using a standard LASSO approach improves the cross-sectional estimation of the M value over routine clinical variables. However, a small subset of these proteins identified using a stability selection algorithm affords much of this improvement, especially when considering cross-cohort analyses. Our approach provides opportunities to improve the identification of insulin-resistant individuals at risk of insulin resistance-related adverse health consequences.

G protein-coupled receptor-targeting antibody-drug conjugates: Current status and future directions

In recent years, antibody-drug conjugates (ADCs) have emerged as promising anti-cancer therapeutic agents with several having already received market approval for the treatment of solid tumor and hematological malignancies. As ADC technology continues to improve and the range of indications treatable by ADCs increases, the repertoire of target antigens has expanded and will undoubtedly continue to grow. G protein-coupled receptors (GPCRs) are well-characterized therapeutic targets implicated in many human pathologies, including cancer, and represent a promising emerging target of ADCs. In this review, we will discuss the past and present therapeutic targeting of GPCRs and describe ADCs as therapeutic modalities. Moreover, we will summarize the status of existing preclinical and clinical GPCR-targeted ADCs and address the potential of GPCRs as novel targets for future ADC development.

Transcriptomics and Phenotypic Analysis of gpr56 Knockout in Zebrafish

The adhesion G-protein-coupled receptor is a seven-transmembrane receptor protein with a complex structure. Impaired GPR56 has been found to cause developmental damage to the human brain, resulting in intellectual disability and motor dysfunction. To date, studies on gpr56 deficiency in zebrafish have been limited to the nervous system, and there have been no reports of its systemic effects on juvenile fish at developmental stages. In order to explore the function of gpr56 in zebrafish, the CRISPR/Cas9 gene-editing system was used to construct a gpr56-knockout zebrafish. Subsequently, the differentially expressed genes (DEGs) at the transcriptional level between the 3 days post fertilization (dpf) homozygotes of the gpr56 mutation and the wildtype zebrafish were analyzed via RNA-seq. The results of the clustering analysis, quantitative PCR (qPCR), and in situ hybridization demonstrated that the expression of innate immunity-related genes in the mutant was disordered, and multiple genes encoding digestive enzymes of the pancreatic exocrine glands were significantly downregulated in the mutant. Motor ability tests demonstrated that the gpr56^-/- zebrafish were more active, and this change was more pronounced in the presence of cold and additional stimuli. In conclusion, our results revealed the effect of gpr56 deletion on the gene expression of juvenile zebrafish and found that the gpr56 mutant was extremely active, providing an important clue for studying the mechanism of gpr56 in the development of juvenile zebrafish.

Data driven and cell specific determination of nuclei-associated actin structure

Quantitative and volumetric assessment of filamentous actin fibers (F-actin) remains challenging due to their interconnected nature, leading researchers to utilize threshold based or qualitative measurement methods with poor reproducibility. Here we introduce a novel machine learning based methodology for accurate quantification and reconstruction of nuclei-associated F-actin. Utilizing a Convolutional Neural Network (CNN), we segment actin filaments and nuclei from 3D confocal microscopy images and then reconstruct each fiber by connecting intersecting contours on cross-sectional slices. This allowed measurement of the total number of actin filaments and individual actin filament length and volume in a reproducible fashion. Focusing on the role of F-actin in supporting nucleocytoskeletal connectivity, we quantified apical F-actin, basal F-actin, and nuclear architecture in mesenchymal stem cells (MSCs) following the disruption of the Linker of Nucleoskeleton and Cytoskeleton (LINC) Complexes. Disabling LINC in mesenchymal stem cells (MSCs) generated F-actin disorganization at the nuclear envelope characterized by shorter length and volume of actin fibers contributing a less elongated nuclear shape. Our findings not only present a new tool for mechanobiology but introduce a novel pipeline for developing realistic computational models based on quantitative measures of F-actin.

Ablation of GPR56 Causes β-Cell Dysfunction by ATP Loss through Mistargeting of Mitochondrial VDAC1 to the Plasma Membrane

The activation of G Protein-Coupled Receptor 56 (GPR56), also referred to as Adhesion G-Protein-Coupled Ceceptor G1 (ADGRG1), by Collagen Type III (Coll III) prompts cell growth, proliferation, and survival, among other attributes. We investigated the signaling cascades mediating this functional effect in relation to the mitochondrial outer membrane voltage-dependent anion Channel-1 (VDAC1) expression in pancreatic β-cells. GPR56KD attenuated the Coll III-induced suppression of P70S6K, JNK, AKT, NFκB, STAT3, and STAT5 phosphorylation/activity in INS-1 cells cultured at 20 mM glucose (glucotoxicity) for 72 h. GPR56-KD also increased Chrebp, Txnip, and Vdac1 while decreasing Vdac2 mRNA expression. In GPR56-KD islet β-cells, Vdac1 was co-localized with SNAP-25, demonstrating its plasma membrane translocation. This resulted in ATP loss, reduced cAMP production and impaired glucose-stimulated insulin secretion (GSIS) in INS-1 and human EndoC βH1 cells. The latter defects were reversed by an acute inhibition of VDAC1 with an antibody or the VDAC1 inhibitor VBIT-4. We demonstrate that Coll III potentiates GSIS by increasing cAMP and preserving β-cell functionality under glucotoxic conditions in a GPR56-dependent manner by attenuating the inflammatory response. These results emphasize GPR56 and VDAC1 as drug targets in conditions with impaired β-cell function.

Role of GPR56 in Platelet Activation and Arterial Thrombosis

The adhesion G protein-coupled receptor GPR56 mediates cell-cell and cell-extracellular matrix interactions. To examine the function of GPR56 in platelet activation and arterial thrombosis, we generated GPR56-knockout mice and evaluated GPR56 expression in human and mouse platelets. The results revealed that the levels of the GPR56 N-terminal fragment were significantly higher on the first day after myocardial infarction than on the seventh day in the plasma of patients with ST-segment-elevation myocardial infarction. Next, we investigated the effects of GPR56 on platelet function in vitro and in vivo. We observed that collagen-induced aggregation and adenosine triphosphate release were reduced in Gpr56 ^-/- platelets. Furthermore, P-selectin expression on the Gpr56 ^-/- platelet surface was also reduced, and the spreading area on immobilized collagen was decreased in Gpr56 ^-/- platelets. Furthermore, collagen-induced platelet activation in human platelets was inhibited by an anti-GPR56 antibody. Gpr56 ^-/- mice showed an extended time to the first occlusion in models with cremaster arteriole laser injury and FeCl₃-induced carotid artery injury. GPR56 activated the G protein 13 signaling pathway following collagen stimulation, which promoted platelet adhesion and thrombus formation at the site of vascular injury. Thus, our study confirmed that GPR56 regulated the formation of arterial thrombosis. Inhibition of the initial response of GPR56 to collagen could significantly inhibit platelet activation and thrombus formation. Our results provide new insights for research into antiplatelet drugs.

Functions of G protein-coupled receptor 56 in health and disease

Human G protein-coupled receptor 56 (GPR56) is encoded by gene ADGRG1 from chromosome 16q21 and is homologously encoded in mice, at chromosome 8. Both 687 and 693 splice forms are present in humans and mice. GPR56 has a 381 amino acid-long N-terminal extracellular segment and a GPCR proteolysis site upstream from the first transmembrane domain. GPR56 is mainly expressed in the heart, brain, thyroid, platelets, and peripheral blood mononuclear cells. Accumulating evidence indicates that GPR56 promotes the formation of myelin sheaths and the development of oligodendrocytes in the cerebral cortex of the central nervous system. Moreover, GPR56 contributes to the development and differentiation of hematopoietic stem cells, induces adipogenesis, and regulates the function of immune cells. The lack of GPR56 leads to nervous system dysfunction, platelet disorders, and infertility. Abnormal expression of GPR56 is related to the malignant transformation and tumor metastasis of several cancers including melanoma, neuroglioma, and gastrointestinal cancer. Metabolic disorders and cardiovascular diseases are also associated with dysregulation of GPR56 expression, and GPR56 is involved in the pharmacological resistance to some antidepressant and cancer drug treatments. In this review, the molecular structure, expression profile, and signal transduction of GPR56 are introduced, and physiological and pathological functions of GRP56 are comprehensively summarized. Attributing to its significant biological functions and its long N-terminal extracellular region that interacts with multiple ligands, GPR56 is becoming an attractive therapeutic target in treating neurological and hematopoietic diseases.

Roles of Focal Adhesion Kinase PTK2 and Integrin αIIbβ3 Signaling in Collagen- and GPVI-Dependent Thrombus Formation under Shear

Glycoprotein (GP)VI and integrin αIIbβ3 are key signaling receptors in collagen-dependent platelet aggregation and in arterial thrombus formation under shear. The multiple downstream signaling pathways are still poorly understood. Here, we focused on disclosing the integrin-dependent roles of focal adhesion kinase (protein tyrosine kinase 2, PTK2), the shear-dependent collagen receptor GPR56 (ADGRG1 gene), and calcium and integrin-binding protein 1 (CIB1). We designed and synthetized peptides that interfered with integrin αIIb binding (pCIB and pCIBm) or mimicked the activation of GPR56 (pGRP). The results show that the combination of pGRP with PTK2 inhibition or of pGRP with pCIB > pCIBm in additive ways suppressed collagen- and GPVI-dependent platelet activation, thrombus buildup, and contraction. Microscopic thrombus formation was assessed by eight parameters (with script descriptions enclosed). The suppressive rather than activating effects of pGRP were confined to blood flow at a high shear rate. Blockage of PTK2 or interference of CIB1 no more than slightly affected thrombus formation at a low shear rate. Peptides did not influence GPVI-induced aggregation and Ca2+ signaling in the absence of shear. Together, these data reveal a shear-dependent signaling axis of PTK2, integrin αIIbβ3, and CIB1 in collagen- and GPVI-dependent thrombus formation, which is modulated by GPR56 and exclusively at high shear. This work thereby supports the role of PTK2 in integrin αIIbβ3 activation and signaling.

Pathophysiological Impact of the Adhesion G-Protein Coupled Receptor Family

G-Protein Coupled Receptors (GPCRs) represent one of the most targeted drug classes in the human genome, accounting for greater than 40% of all FDA-approved drugs. However, the second-largest family of GPCRs, known as Adhesion GPCRs (aGPCR), have yet to serve as a clinical target despite increasing evidence of their physiological and pathological functions, which suggest an opportunity toward the development of novel therapeutics. To date, the pathophysiological function of aGPCRs is associated with a plethora of diseases including cancer, CNS disorders, immunity and inflammation, and others. To highlight their potential as pharmacologic targets, we will review three distinct aGPCR members (ADGRG1, ADGRE5 and ADGRF5), highlighting their molecular mechanisms of action and contributions to the development of pathophysiology.

Transcriptomic profiles of neoantigen-reactive T cells in human gastrointestinal cancers

Tumor-infiltrating neoantigen-reactive T cells can mediate regression of metastatic gastrointestinal cancers yet remain poorly characterized. We performed immunological screening against personalized neoantigens in combination with single-cell RNA sequencing on tumor-infiltrating lymphocytes from bile duct and pancreatic cancer patients to characterize the transcriptomic landscape of neoantigen-reactive T cells. We found that most neoantigen-reactive CD8⁺ T cells displayed an exhausted state with significant CXCL13 and GZMA co-expression compared with non-neoantigen-reactive bystander cells. Most neoantigen-reactive CD4⁺ T cells from a patient with bile duct cancer also exhibited an exhausted phenotype but with overexpression of HOPX or ADGRG1 while lacking IL7R expression. Thus, neoantigen-reactive T cells infiltrating gastrointestinal cancers harbor distinct transcriptomic signatures, which may provide new opportunities for harnessing these cells for therapy.

Ligands and Beyond: Mechanosensitive Adhesion GPCRs

Cells respond to diverse types of mechanical stimuli using a wide range of plasma membrane-associated mechanosensitive receptors to convert extracellular mechanical cues into intracellular signaling. G protein-coupled receptors (GPCRs) represent the largest cell surface protein superfamily that function as versatile sensors for a broad spectrum of bio/chemical messages. In recent years, accumulating evidence has shown that GPCRs can also engage in mechano-transduction. According to the GRAFS classification system of GPCRs, adhesion GPCRs (aGPCRs) constitute the second largest GPCR subfamily with a unique modular protein architecture and post-translational modification that are well adapted for mechanosensory functions. Here, we present a critical review of current evidence on mechanosensitive aGPCRs.

Role of ADGRG1/GPR56 in Tumor Progression

Cellular communication plays a critical role in diverse aspects of tumorigenesis including tumor cell growth/death, adhesion/detachment, migration/invasion, angiogenesis, and metastasis. G protein-coupled receptors (GPCRs) which constitute the largest group of cell surface receptors are known to play fundamental roles in all these processes. When considering the importance of GPCRs in tumorigenesis, the adhesion GPCRs (aGPCRs) are unique due to their hybrid structural organization of a long extracellular cell-adhesive domain and a seven-transmembrane signaling domain. Indeed, aGPCRs have been increasingly shown to be associated with tumor development by participating in tumor cell interaction and signaling. ADGRG1/GPR56, a representative tumor-associated aGPCR, is recognized as a potential biomarker/prognostic factor of specific cancer types with both tumor-suppressive and tumor-promoting functions. We summarize herein the latest findings of the role of ADGRG1/GPR56 in tumor progression.

Greek gods and the double-edged sword of liver regeneration

In the current issue of the Biomedical Journal we gain an insight into the regeneration of liver tissue and how an over-the-counter supplement, stem cells and two plant extracts counteract liver damage. Furthermore the advances against hepatitis C virus are presented, the role of long non-coding RNA elucidated as well as the potential of an adhesion G protein-coupled receptor. In another contribution, the definition and evolutionary impact of copy number variants is clarified. Also, the polymorphism of a scaffolding caspase is investigated. We furthermore learn about the relation between SARS-CoV2 mutants in dependence of geography and explore the challenges of telemedicine in a complex healthcare field. A novel approach to engineering artificial grafts is presented, the challenges of total knee arthroplasty discussed as well as a possible mean of sinus floor elevation for dental implants. At last the concept of flipped classroom is scrutinized in terms of usefulness for a hospital in Taiwan.