Epigenetic insights into Familial Mediterranean Fever: Increased RGS10 expression and histone modifications accompanies inflammation in familial Mediterranean fever disease

BACKGROUND

Familial Mediterranean fever (FMF) is an autosomal recessive autoinflammatory disease characterized by recurring fever, erythema, joint pain, and abdominal discomfort during acute episodes. While FMF patients typically share MEFV gene mutations, they display varying clinical manifestations, suggesting the involvement of modifying genes, epigenetic mechanisms, or environmental factors. G protein regulator signal 10 (RGS10), a member of the RGS protein family, exhibits anti-inflammatory effects in autoinflammatory diseases. There are no studies on the role of plays in FMF pathogenesis or histone modification in FMF.

AIMS

This study aimed to shed light on the epigenetic regulation of FMF from several perspectives. The relationship between RGS10 DNA hypermethylation in FMF clinical parameters and the regulation of 22 histone modifications were examined in FMF attack patients and the control group.

METHODS

Sixty FMF (remission/attack) and thirty healthy individuals were included in the study. First, RNA was isolated from the blood of patients/controls, and the expression of RGS10 was examined. Then, DNA was isolated from the patients, and gene-specific hypermethylation was investigated using the bisulfite conversion method. Finally, histone extraction was performed for FMF patients and controls and 22 histone H3 modifications were determined. In addition, using ADEX bioinformatics tools, RGS10 expression and methylation profiles were detected in different autoinflammatory diseases.

RESULTS

This study indicate that RGS10 expression decreased in attack-free/attack patients than control, attributed to DNA methylation. In addition, there were a positive correlation between FMF patients and attack, WBC, neutrophil, MCHC and MPV. Moreover, higher H3K4 me3, H3K9 me2, and H3K14ac levels were observed in patients with FMF attacks. This research also showed a consistent decrease in RGS10 expression in patients with SjS, SSc, and T1D compared with controls. I also obtained five prognosis-related CpGs (cg17527393, cg19653161, cg20445950, cg18938673 and cg13975098) of RGS10 in patients with SjS, RA, SSc, SLE and T1D.

CONCLUSION

The present study provides insights into the complex relationship between RGS10, epigenetic modifications, and immune responses in FMF. While RGS10 may initially enhance immune responses, genetic mutations and epigenetic changes associated with FMF acute episode may override this regulatory effect, resulting in increased inflammation and clinical symptoms. Moreover, our study revealed elevated levels of specific histone modifications in the context of FMF, suggesting significant epigenetic changes that could contribute to the disease pathogenesis. Understanding these associations opens new avenues for research and potential therapeutic interventions, potentially involving epigenetic therapies targeting histone modifications.

RGS4 Actions in Mouse Prefrontal Cortex Modulate Behavioral and Transcriptomic Responses to Chronic Stress and Ketamine

The signal transduction protein, regulator of G protein signaling 4 (RGS4), plays a prominent role in physiologic and pharmacological responses by controlling multiple intracellular pathways. Our earlier work identified the dynamic but distinct roles of RGS4 in the efficacy of monoamine-targeting versus fast-acting antidepressants. Using a modified chronic variable stress (CVS) paradigm in mice, we demonstrate that stress-induced behavioral abnormalities are associated with the downregulation of RGS4 in the medial prefrontal cortex (mPFC). Knockout of RGS4 (RGS4KO) increases susceptibility to CVS, as mutant mice develop behavioral abnormalities as early as 2 weeks after CVS resting-state functional magnetic resonance imaging I (rs-fMRI) experiments indicate that stress susceptibility in RGS4KO mice is associated with changes in connectivity between the mediodorsal thalamus (MD-THL) and the mPFC. Notably, RGS4KO also paradoxically enhances the antidepressant efficacy of ketamine in the CVS paradigm. RNA-sequencing analysis of naive and CVS samples obtained from mPFC reveals that RGS4KO triggers unique gene expression signatures and affects several intracellular pathways associated with human major depressive disorder. Our analysis suggests that ketamine treatment in the RGS4KO group triggers changes in pathways implicated in synaptic activity and responses to stress, including pathways associated with axonal guidance and myelination. Overall, we show that reducing RGS4 activity triggers unique gene expression adaptations that contribute to chronic stress disorders and that RGS4 is a negative modulator of ketamine actions. SIGNIFICANCE STATEMENT: Chronic stress promotes robust maladaptation in the brain, but the exact intracellular pathways contributing to stress vulnerability and mood disorders have not been thoroughly investigated. In this study, the authors used murine models of chronic stress and multiple methodologies to demonstrate the critical role of the signal transduction modulator regulator of G protein signaling 4 in the medial prefrontal cortex in vulnerability to chronic stress and the efficacy of the fast-acting antidepressant ketamine.

Regulator of G protein signalling 18 promotes osteocyte proliferation by activating the extracellular signal‑regulated kinase signalling pathway

Osteocyte function is critical for metabolism, remodelling and regeneration of bone tissue. In the present study, the roles of regulator of G protein signalling 18 (RGS18) were assessed in the regulation of osteocyte proliferation and bone formation. Target genes and signalling pathways were screened using the Gene Expression Omnibus (GEO) database and Gene Set Enrichment Analysis (GSEA). The function of RGS18 and the associated mechanisms were analysed by Cell Counting Kit 8 assay, 5‑ethynyl‑2'‑deoxyuridine assay, flow cytometry, reverse transcription‑quantitative PCR, western blotting and immunostaining. Overlap analysis of acutely injured subjects (AIS) and healthy volunteers (HVs) from the GSE93138 and GSE93215 datasets of the GEO database identified four genes: KIAA0825, ANXA3, RGS18 and LIPN. Notably, RGS18 was more highly expressed in peripheral blood samples from AIS than in those from HVs. Furthermore, RGS18 overexpression promoted MLO‑Y4 and MC3T3‑E1 cell viability, proliferation and S‑phase arrest, but inhibited apoptosis by suppressing caspase‑3/9 cleavage. Silencing RGS18 exerted the opposite effects. GSEA of GSE93138 revealed that RGS18 has the ability to regulate MAPK signalling. Treatment with the MEK1/2 inhibitor PD98059 reversed the RGS18 overexpression‑induced osteocyte proliferation, and treatment with the ERK1/2 activator 12‑O‑tetradecanoylphorbol‑13‑acetate reversed the effects of RGS18 silencing on osteocyte proliferation. In conclusion, RGS18 may contribute to osteocyte proliferation and bone fracture healing via activation of ERK signalling.

RGS6 drives cardiomyocyte death following nucleolar stress by suppressing Nucleolin/miRNA-21

BACKGROUND

Prior evidence demonstrated that Regulator of G protein Signaling 6 (RGS6) translocates to the nucleolus in response to cytotoxic stress though the functional significance of this phenomenon remains unknown.

METHODS

Utilizing in vivo gene manipulations in mice, primary murine cardiac cells, human cell lines and human patient samples we dissect the participation of a RGS6-nucleolin complex in chemotherapy-dependent cardiotoxicity.

RESULTS

Here we demonstrate that RGS6 binds to a key nucleolar protein, Nucleolin, and controls its expression and activity in cardiomyocytes. In the human myocyte AC-16 cell line, induced pluripotent stem cell derived cardiomyocytes, primary murine cardiomyocytes, and the intact murine myocardium tuning RGS6 levels via overexpression or knockdown resulted in diametrically opposed impacts on Nucleolin mRNA, protein, and phosphorylation.RGS6 depletion provided marked protection against nucleolar stress-mediated cell death in vitro, and, conversely, RGS6 overexpression suppressed ribosomal RNA production, a key output of the nucleolus, and triggered death of myocytes. Importantly, overexpression of either Nucleolin or Nucleolin effector miRNA-21 counteracted the pro-apoptotic effects of RGS6. In both human and murine heart tissue, exposure to the genotoxic stressor doxorubicin was associated with an increase in the ratio of RGS6/Nucleolin. Preventing RGS6 induction via introduction of RGS6-directed shRNA via intracardiac injection proved cardioprotective in mice and was accompanied by restored Nucleolin/miRNA-21 expression, decreased nucleolar stress, and decreased expression of pro-apoptotic, hypertrophy, and oxidative stress markers in heart.

CONCLUSION

Together, these data implicate RGS6 as a driver of nucleolar stress-dependent cell death in cardiomyocytes via its ability to modulate Nucleolin. This work represents the first demonstration of a functional role for an RGS protein in the nucleolus and identifies the RGS6/Nucleolin interaction as a possible new therapeutic target in the prevention of cardiotoxicity.

Phosphorylation Dynamics in a flg22-Induced, G Protein-Dependent Network Reveals the AtRGS1 Phosphatase

The microbe-associated molecular pattern flg22 is recognized in a flagellin-sensitive 2-dependent manner in root tip cells. Here, we show a rapid and massive change in protein abundance and phosphorylation state of the Arabidopsis root cell proteome in WT and a mutant deficient in heterotrimeric G-protein-coupled signaling. flg22-induced changes fall on proteins comprising a subset of this proteome, the heterotrimeric G protein interactome, and on highly-populated hubs of the immunity network. Approximately 95% of the phosphorylation changes in the heterotrimeric G-protein interactome depend, at least partially, on a functional G protein complex. One member of this interactome is ATBα, a substrate-recognition subunit of a protein phosphatase 2A complex and an interactor to Arabidopsis thaliana Regulator of G Signaling 1 protein (AtRGS1), a flg22-phosphorylated, 7-transmembrane spanning modulator of the nucleotide-binding state of the core G-protein complex. A null mutation of ATBα strongly increases basal endocytosis of AtRGS1. AtRGS1 steady-state protein level is lower in the atbα mutant in a proteasome-dependent manner. We propose that phosphorylation-dependent endocytosis of AtRGS1 is part of the mechanism to degrade AtRGS1, thus sustaining activation of the heterotrimeric G protein complex required for the regulation of system dynamics in innate immunity. The PP2A(ATBα) complex is a critical regulator of this signaling pathway.

RGS10 inhibits proliferation and migration of pulmonary arterial smooth muscle cell in pulmonary hypertension via AKT/mTORC1 signaling

Objective: Excessive proliferation and migration of pulmonary arterial smooth muscle cell (PASMC) is a core event of pulmonary hypertension (PH). Regulators of G protein signaling 10 (RGS10) can regulate cellular proliferation and cardiopulmonary diseases. We demonstrate whether RGS10 also serves as a regulator of PH.Methods: PASMC was challenged by hypoxia to induce proliferation and migration. Adenovirus carrying Rgs10 gene (Ad-Rgs10) was used for external expression of Rgs10. Hypoxia/SU5416 or MCT was used to induce PH. Right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) were used to validate the establishment of PH model.Results: RGS10 was downregulated in hypoxia-challenged PASMC. Ad-Rgs10 significantly suppressed proliferation and migration of PASMC after hypoxia stimulus, while silencing RGS10 showed contrary effect. Mechanistically, we observed that phosphorylation of S6 and 4E-Binding Protein 1 (4EBP1), the main downstream effectors of mammalian target of rapamycin complex 1 (mTORC1) as well as phosphorylation of AKT, the canonical upstream of mTORC1 in hypoxia-induced PASMC were negatively modulated by RGS10. Both recovering mTORC1 activity and restoring AKT activity abolished these effects of RGS10 on PASMC. More importantly, AKT activation also abolished the inhibitory role of RGS10 in mTORC1 activity in hypoxia-challenged PASMC. Finally, we also observed that overexpression of RGS10 in vivo ameliorated pulmonary vascular wall thickening and reducing RVSP and RVHI in mouse PH model.Conclusion: Our findings reveal the modulatory role of RGS10 in PASMC and PH via AKT/mTORC1 axis. Therefore, targeting RGS10 may serve as a novel potent method for the prevention against PH."

RGS proteins and cardiovascular Angiotensin II Signaling: Novel opportunities for therapeutic targeting

Angiotensin II (AngII), as an octapeptide hormone normally ionized at physiological pH, cannot cross cell membranes and thus, relies on, two (mainly) G protein-coupled receptor (GPCR) types, AT1R and AT2R, to exert its intracellular effects in various organ systems including the cardiovascular one. Although a lot remains to be elucidated about the signaling of the AT2R, AT1R signaling is known to be remarkably versatile, mobilizing a variety of G protein-dependent and independent signal transduction pathways inside cells to produce a biological outcome. Cardiac AT1R signaling leads to hypertrophy, adverse remodeling, fibrosis, while vascular AT1R signaling raises blood pressure via vasoconstriction, but also elicits hypertrophic, vascular growth/proliferation, and pathological remodeling sets of events. In addition, adrenal AT1R is the major physiological stimulus (alongside hyperkalemia) for secretion of aldosterone, a mineralocorticoid hormone that contributes to hypertension, electrolyte abnormalities, and to pathological remodeling of the failing heart. Regulator of G protein Signaling (RGS) proteins, discovered about 25 years ago as GTPase-activating proteins (GAPs) for the Gα subunits of heterotrimeric G proteins, play a central role in silencing G protein signaling from a plethora of GPCRs, including the AngII receptors. Given the importance of AngII and its receptors, but also of several RGS proteins, in cardiovascular homeostasis, the physiological and pathological significance of RGS protein-mediated modulation of cardiovascular AngII signaling comes as no surprise. In the present review, we provide an overview of the current literature on the involvement of RGS proteins in cardiovascular AngII signaling, by discussing their roles in cardiac (cardiomyocyte and cardiofibroblast), vascular (smooth muscle and endothelial cell), and adrenal (medulla and cortex) AngII signaling, separately. Along the way, we also highlight the therapeutic potential of enhancement of, or, in some cases, inhibition of each RGS protein involved in AngII signaling in each one of these cell types.

RGS1 Modulates Autophagic and Metabolic Programs and Is a Critical Mediator of Human Regulatory T Cell Function

Regulatory T cells (Tregs) are critical mediators of immune tolerance and play a diametric role in cancer and autoimmunity. Tumor-infiltrating Tregs are often associated with poor prognosis in solid tumors because their enrichment in the tumor microenvironment contributes to immunosuppression. Conversely, dysregulation in the Treg compartment can disrupt self-tolerance, leading to autoimmunity. In the present study, we describe what is, to our knowledge, a novel regulator of Tregs, the GTPase activator regulator of G protein 1 (RGS1), demonstrating that RGS1-deficient human Tregs show downregulation of Treg-associated genes and are less immunosuppressive. These RGS1-deficient Tregs exhibit perturbations to the FOXP3-c-MYC transcriptional axis and downstream metabolic and autophagy programs by shifting their energy demands toward glycolysis and rendering them less autophagic. Taken together, RGS1 may serve as an apical node of Treg function by regulating the FOXP3-c-MYC transcriptional axis, thereby providing a therapeutic rationale for targeting RGS1 for treatment of cancer and autoimmune diseases.

RGS1 mediates renal interstitial fibrosis through activation of the inflammatory response

Renal interstitial fibrosis (RIF) is considered as a common pathway for all patients with chronic kidney disease (CKD) to progress to end-stage kidney disease (ESRD). The basic pathological manifestation is the increase of matrix component in the tubular interstitium, while the injury of tubular epithelial cells in the renal interstitium and the excessive accumulation of matrix will eventually lead to tubular atrophy and obstruction, loss of effective renal units, and finally impaired renal filtration function. The relevant mechanism of RIF remains unclear. The present study will investigate the function and relevant mechanism of RGS1 in RIF. The RIF-related microarrays GSE22459 and GSE76882 were downloaded and analyzed. Renal parenchymal atrophic calyx tissues were collected from clinical RIF patients. Cellular inflammation, fibrosis and animal RIF models were constructed using Lipopolysaccharide (LPS), TGF-β1 and unilateral ureteral occlusion (UUO). HE and Masson staining were performed to detect morphological alterations of renal tissue samples. qRT-PCR, Western blot and ELISA were carried out to detect the expression of relevant genes/proteins. RGS1 is a gene co-differentially expressed by GSE22459 and GSE76882. RGS1 expression was elevated in renal tissues of RIF patients, cells and animal RIF models. Knockdown of RGS1 inhibited renal cell inflammatory response, fibrosis and renal fibrosis in RIF mice. Overexpression of RGS1 plays the opposite role. Knockdown of RGS1 inhibited the inflammatory response in the RIF cell and mouse model. Targeting RGS1 might be a potential therapeutic strategy for RIF treatment.

A regulatory node involving Gαq, PLCβ, and RGS proteins modulates platelet reactivity to critical agonists

BACKGROUND

Most platelet agonists work through G protein-coupled receptors, activating pathways that involve members of the Gq, Gi, and G12/G13 families of heterotrimeric G proteins. Gq signaling has been shown to be critical for efficient platelet activation. Growing evidence suggests that regulatory mechanisms converge on G protein-coupled receptors and Gq to prevent overly robust platelet reactivity.

OBJECTIVES

To identify and characterize mechanisms by which Gq signaling is regulated in platelets.

METHODS

Based on our prior experience with a Gαi2 variant that escapes regulation by regulator of G protein signaling (RGS) proteins, a Gαq variant was designed with glycine 188 replaced with serine (G188S) and then incorporated into a mouse line so that its effects on platelet activation and thrombus formation could be studied in vitro and in vivo.

RESULTS AND CONCLUSIONS

As predicted, the G188S substitution in Gαq disrupted its interaction with RGS18. Unexpectedly, it also uncoupled PLCβ-3 from activation by platelet agonists as evidenced by a loss rather than a gain of platelet function in vitro and in vivo. Binding studies showed that in addition to preventing the binding of RGS18 to Gαq, the G188S substitution also prevented the binding of PLCβ-3 to Gαq. Structural analysis revealed that G188 resides in the region that is also important for Gαq binding to PLCβ-3 in platelets. We conclude that the Gαq signaling node is more complex than that has been previously understood, suggesting that there is cross-talk between RGS proteins and PLCβ-3 in the context of Gαq signaling.

RGS5 maintaining vascular homeostasis is altered by the tumor microenvironment

BACKGROUND

Regulator of G protein signaling 5 (RGS5), as a negative regulator of G protein-coupled receptor (GPCR) signaling, is highly expressed in arterial VSMCs and pericytes, which is involved in VSMC phenotypic heterogeneity and vascular remodeling in tumors. However, its role in normal and tumor vascular remodeling is controversial.

METHODS

RGS5 knockout (Rgs5-KO) mice and RGS5 overexpression or knockdown in VSMCs in vivo by adeno-associated virus type 9 (AAV) carrying RGS5 cDNA or small hairpin RNA (shRNA) targeting RGS5 were used to determine the functional significance of RGS5 in vascular inflammation. RGS5 expression in the triple-negative (TNBCs) and non-triple-negative breast cancers (Non-TNBCs) was determined by immunofluorescent and immunohistochemical staining. The effect of breast cancer cell-conditioned media (BC-CM) on the pro-inflammatory phenotype of VSMCs was measured by phagocytic activity assays, adhesion assay and Western blot.

RESULTS

We identified that knockout and VSMC-specific knockdown of RGS5 exacerbated accumulation and pyroptosis of pro-inflammatory VSMCs, resulting in vascular remodeling, which was negated by VSMC-specific RGS5 overexpression. In contrast, in the context of breast cancer tissues, the role of RGS5 was completely disrupted. RGS5 expression was increased in the triple-negative breast cancer (TNBC) tissues and in the tumor blood vessels, accompanied with an extensive vascular network. VSMCs treated with BC-CM displayed enhanced pro-inflammatory phenotype and higher adherent with macrophages. Furthermore, tumor-derived RGS5 could be transferred into VSMCs.

CONCLUSIONS

These findings suggest that tumor microenvironment shifts the function of RGS5 from anti-inflammation to pro-inflammation and induces the pro-inflammatory phenotype of VSMCs that is favorable for tumor metastasis.

A longitudinal genome-wide association study of bone mineral density mean and variability in the UK Biobank

Bone mineral density (BMD) is an essential predictor of osteoporosis and fracture. We conducted a genome-wide trajectory analysis of BMD and analyzed the BMD change.

PURPOSE

This study aimed to identify the genetic architecture and potential biomarkers of BMD.

METHODS

Our analysis included 141,261 white participants from the UK Biobank with heel BMD phenotype data. We used a genome-wide trajectory analysis tool, TrajGWAS, to conduct a genome-wide association study (GWAS) of BMD. Then, we validated our findings in previously reported BMD genetic associations and performed replication analysis in the Asian participants. Finally, gene-set enrichment analysis (GSEA) of the identified candidate genes was conducted using the FUMA platform.

RESULTS

A total of 52 genes associated with BMD trajectory mean were identified, of which the top three significant genes were WNT16 (P = 1.31 × 10-126), FAM3C (P = 4.18 × 10-108), and CPED1 (P = 8.48 × 10-106). In addition, 114 genes associated with BMD within-subject variability were also identified, such as AC092079.1 (P = 2.72 × 10-13) and RGS7 (P = 4.72 × 10-10). The associations for these candidate genes were confirmed in the previous GWASs and replicated successfully in the Asian participants. GSEA results of BMD change identified multiple GO terms related to skeletal development, such as SKELETAL SYSTEM DEVELOPMENT (Padjusted = 2.45 × 10-3) and REGULATION OF OSSIFICATION (Padjusted = 2.45 × 10-3). KEGG enrichment analysis showed that these genes were mainly enriched in WNT SIGNALING PATHWAY.

CONCLUSIONS

Our findings indicated that the CPED1-WNT16-FAM3C locus plays a significant role in BMD mean trajectories and identified several novel candidate genes contributing to BMD within-subject variability, facilitating the understanding of the genetic architecture of BMD.

RGS5 as a Biomarker of Pericytes, Involvement in Vascular Remodeling and Pulmonary Arterial Hypertension

Introduction

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by a sustained rise in mean pulmonary artery pressure. Pulmonary vascular remodeling serves an important role in PAH. Identifying a key driver gene to regulate vascular remodeling of the pulmonary microvasculature is critical for PAH management.

Methods

Differentially expressed genes were identified using the Gene Expression Omnibus (GEO) GSE117261, GSE48149, GSE113439, GSE53408 and GSE16947 datasets. A co-expression network was constructed using weighted gene co-expression network analysis. Novel and key signatures of PAH were screened using four algorithms, including weighted gene co-expression network analysis, GEO2R analysis, support vector machines recursive feature elimination and robust rank aggregation rank analysis. Regulator of G-protein signaling 5 (RGS5), a pro-apoptotic/anti-proliferative protein, which regulate arterial tone and blood pressure in vascular smooth muscle cells. The expression of RGS5 was determined using reverse transcription-quantitative PCR (RT-qPCR) in PAH and normal mice. The location of RGS5 and pericytes was detected using immunofluorescence.

Results

Compared with that in the normal group, RGS5 expression was upregulated in the PAH group based on GEO and RT-qPCR analyses. RGS5 expression in single cells was enriched in pericytes in single-cell RNA sequencing analysis. RGS5 co-localization with pericytes was detected in the pulmonary microvasculature of PAH.

Conclusion

RGS5 regulates vascular remodeling of the pulmonary microvasculature and the occurrence of PAH through pericytes, which has provided novel ideas and strategies regarding the occurrence and innovative treatment of PAH.

Lnc‑RGS5 sponges miR‑542‑5p to promote FoxM1/VEGFA signaling and breast cancer cell proliferation

Breast cancer (BRCA) exhibits a high incidence rate among women worldwide. LOC127814295 (ENSG00000232995), termed long non‑coding (lnc)‑regulator of G protein signaling 5 (RGS5), is a novel lncRNA with a genomic region overlapping with protein‑coding gene RGS5. Results obtained using The Cancer Genome Atlas demonstrated that lnc‑RGS5 was deregulated in diverse cancer types, including BRCA; however, the functional role of lnc‑RGS5 remains unclear. Results of the present study demonstrated that lnc‑RGS5 was upregulated in BRCA tissues compared with healthy samples (n=30; P<0.0001), and was associated with the overall survival of patients with triple‑negative BRCA (n=106; P<0.05). Moreover, lnc‑RGS5 expression was significantly higher in triple‑negative BRCA samples than in LumA, LumB, or Her2 subtypes (P<0.05). Functionally, lnc‑RGS5 upregulation promoted BRCA cell proliferation in vitro, whereas lnc‑RGS5 knockdown elicited the opposite function. Stable knockdown of lnc‑RGS5 inhibited tumor cell proliferation in vivo. Bioinformatics analysis revealed that lnc‑RGS5 was significantly associated with RNA binding involved in post‑transcriptional gene silencing (P=0.002). Mechanistically, lnc‑RGS5 functions as a competing endogenous RNA via competitively sponging miR‑542‑5p to upregulate forkhead box M1 (FoxM1) and the VEGFA/Neuropilin 1 axis; thus, promoting BRCA cell proliferation in vitro. Moreover, rescue experiments validated that the lnc‑RGS5/miR‑542‑5p/FoxM1 axis promoted BRCA cell growth in vivo. Collectively, results of the present study demonstrated that lnc‑RGS5 may exhibit potential as a novel oncogenic lncRNA in BRCA. The present study may provide a novel theoretical basis for the role of lncRNA in the targeted therapy of BRCA.

Listeria-based vaccination against the pericyte antigen RGS5 elicits anti-vascular effects and colon cancer protection

Colorectal cancer (CRC) remains a leading cause of cancer-related mortality despite efforts to improve standard interventions. As CRC patients can benefit from immunotherapeutic strategies that incite effector T cell action, cancer vaccines represent a safe and promising therapeutic approach to elicit protective and durable immune responses against components of the tumor microenvironment (TME). In this study, we investigate the pre-clinical potential of a Listeria monocytogenes (Lm)-based vaccine targeting the CRC-associated vasculature. CRC survival and progression are reliant on functioning blood vessels to effectively mediate various metabolic processes and oxygenate underlying tissues. We, therefore, advance the strategy of initiating immunity in syngeneic mouse models against the endogenous pericyte antigen RGS5, which is a critical mediator of pathological vascularization. Overall, Lm-based vaccination safely induced potent anti-tumor effects that consisted of recruiting functional Type-1-associated T cells into the TME and reducing tumor blood vessel content. This study underscores the promising clinical potential of targeting RGS5 against vascularized tumors like CRC.

Identification of Breast Cancer Metastasis Markers from Gene Expression Profiles Using Machine Learning Approaches

Cancer metastasis accounts for approximately 90% of cancer deaths, and elucidating markers in metastasis is the first step in its prevention. To characterize metastasis marker genes (MGs) of breast cancer, XGBoost models that classify metastasis status were trained with gene expression profiles from TCGA. Then, a metastasis score (MS) was assigned to each gene by calculating the inner product between the feature importance and the AUC performance of the models. As a result, 54, 202, and 357 genes with the highest MS were characterized as MGs by empirical p-value cutoffs of 0.001, 0.005, and 0.01, respectively. The three sets of MGs were compared with those from existing metastasis marker databases, which provided significant results in most comparisons (p-value < 0.05). They were also significantly enriched in biological processes associated with breast cancer metastasis. The three MGs, SPPL2C, KRT23, and RGS7, showed highly significant results (p-value < 0.01) in the survival analysis. The MGs that could not be identified by statistical analysis (e.g., GOLM1, ELAVL1, UBP1, and AZGP1), as well as the MGs with the highest MS (e.g., ZNF676, FAM163B, LDOC2, IRF1, and STK40), were verified via the literature. Additionally, we checked how close the MGs were to each other in the protein-protein interaction networks. We expect that the characterized markers will help understand and prevent breast cancer metastasis.

RGS5 augments astrocyte activation and facilitates neuroinflammation via TNF signaling

Astrocytes contribute to chronic neuroinflammation in a variety of neurodegenerative diseases, including Parkinson's disease (PD), the most common movement disorder. However, the precise role of astrocytes in neuroinflammation remains incompletely understood. Herein, we show that regulator of G-protein signaling 5 (RGS5) promotes neurodegenerative process through augmenting astrocytic tumor necrosis factor receptor (TNFR) signaling. We found that selective ablation of Rgs5 in astrocytes caused an inhibition in the production of cytokines resulting in mitigated neuroinflammatory response and neuronal survival in animal models of PD, whereas overexpression of Rgs5 had the opposite effects. Mechanistically, RGS5 switched astrocytes from neuroprotective to pro-inflammatory property via binding to the receptor TNFR2. RGS5 also augmented TNFR signaling-mediated pro-inflammatory response by interacting with the receptor TNFR1. Moreover, interrupting RGS5/TNFR interaction by either RGS5 aa 1-108 or small molecular compounds feshurin and butein, suppressed astrocytic cytokine production. We showed that the transcription of astrocytic RGS5 was controlled by transcription factor early B cell factor 1 whose expression was reciprocally influenced by RGS5-modulated TNF signaling. Thus, our study indicates that beyond its traditional role in G-protein coupled receptor signaling, astrocytic RGS5 is a key modulator of TNF signaling circuit with resultant activation of astrocytes thereby contributing to chronic neuroinflammation. Blockade of the astrocytic RGS5/TNFR interaction is a potential therapeutic strategy for neuroinflammation-associated neurodegenerative diseases.

RGS7 balances acetylation/de-acetylation of p65 to control chemotherapy-dependent cardiac inflammation

Cardiotoxicity remains a major limitation in the clinical utility of anthracycline chemotherapeutics. Regulator of G-protein Signaling 7 (RGS7) and inflammatory markers are up-regulated in the hearts of patients with a history of chemotherapy particularly those with reduced left-ventricular function. RGS7 knockdown in either the murine myocardium or isolated murine ventricular cardiac myocytes (VCM) or cultured human VCM provided marked protection against doxorubicin-dependent oxidative stress, NF-κB activation, inflammatory cytokine production, and cell death. In exploring possible mechanisms causally linking RGS7 to pro-inflammatory signaling cascades, we found that RGS7 forms a complex with acetylase Tip60 and deacetylase sirtuin 1 (SIRT1) and controls the acetylation status of the p65 subunit of NF-κB. In VCM, the detrimental impact of RGS7 could be mitigated by inhibiting Tip60 or activating SIRT1, indicating that the ability of RGS7 to modulate cellular acetylation capacity is critical for its pro-inflammatory actions. Further, RGS7-driven, Tip60/SIRT1-dependent cytokines released from ventricular cardiac myocytes and transplanted onto cardiac fibroblasts increased oxidative stress, markers of transdifferentiation, and activity of extracellular matrix remodelers emphasizing the importance of the RGS7-Tip60-SIRT1 complex in paracrine signaling in the myocardium. Importantly, while RGS7 overexpression in heart resulted in sterile inflammation, fibrotic remodeling, and compromised left-ventricular function, activation of SIRT1 counteracted the detrimental impact of RGS7 in heart confirming that RGS7 increases acetylation of SIRT1 substrates and thereby drives cardiac dysfunction. Together, our data identify RGS7 as an amplifier of inflammatory signaling in heart and possible therapeutic target in chemotherapeutic drug-induced cardiotoxicity.

Cardiac RGS7 and RGS11 drive TGFβ1-dependent liver damage following chemotherapy exposure

Off target damage to vital organ systems is an unfortunate side effect of cancer chemotherapy and remains a major limitation to the use of these essential drugs in the clinic. Despite decades of research, the mechanisms conferring susceptibility to chemotherapy driven cardiotoxicity and hepatotoxicity remain unclear. In the livers of patients with a history of chemotherapy, we observed a twofold increase in expression of G protein regulator RGS7 and a corresponding decrease in fellow R7 family member RGS11. Knockdown of RGS7 via introduction of RGS7 shRNA via tail vein injection decreased doxorubicin-induced hepatic collagen and lipid deposition, glycogen accumulation, and elevations in ALT, AST, and triglycerides by approximately 50%. Surprisingly, a similar result could be achieved via introduction of RGS7 shRNA directly to the myocardium without impacting RGS7 levels in the liver directly. Indeed, doxorubicin-treated cardiomyocytes secrete the endocrine factors transforming growth factor β1 (TGFβ1) and TGFβ superfamily binding protein follistatin-related protein 1 (FSTL1). Importantly, RGS7 overexpression in the heart was sufficient to recapitulate the impacts of doxorubicin on the liver and inhibition of TGFβ1 signaling with the receptor blocker GW788388 ameliorated the effect of cardiac RGS7 overexpression on hepatic fibrosis, steatosis, oxidative stress, and cell death as well as the resultant elevation in liver enzymes. Together these data demonstrate that RGS7 controls both the release of TGFβ1 from the heart and the profibrotic and pro-oxidant actions of TGFβ1 in the liver and emphasize the functional significance of endocrine cardiokine signaling in the pathogenesis of chemotherapy drive multiorgan damage.

Mechanisms of mGluR-dependent plasticity in hippocampal area CA2

Pyramidal cells in hippocampal area CA2 have synaptic properties that are distinct from the other CA subregions. Notably, this includes a lack of typical long-term potentiation of stratum radiatum synapses. CA2 neurons express high levels of several known and potential regulators of metabotropic glutamate receptor (mGluR)-dependent signaling including Striatal-Enriched Tyrosine Phosphatase (STEP) and several Regulator of G-protein Signaling (RGS) proteins, yet the functions of these proteins in regulating mGluR-dependent synaptic plasticity in CA2 are completely unknown. Thus, the aim of this study was to examine mGluR-dependent synaptic depression and to determine whether STEP and the RGS proteins RGS4 and RGS14 are involved. Using whole cell voltage-clamp recordings from mouse pyramidal cells, we found that mGluR agonist-induced long-term depression (mGluR-LTD) is more pronounced in CA2 compared with that observed in CA1. This mGluR-LTD in CA2 was found to be protein synthesis and STEP dependent, suggesting that CA2 mGluR-LTD shares mechanistic processes with those seen in CA1, but in addition, RGS14, but not RGS4, was essential for mGluR-LTD in CA2. In addition, we found that exogenous application of STEP could rescue mGluR-LTD in RGS14 KO slices. Supporting a role for CA2 synaptic plasticity in social cognition, we found that RGS14 KO mice had impaired social recognition memory as assessed in a social discrimination task. These results highlight possible roles for mGluRs, RGS14, and STEP in CA2-dependent behaviors, perhaps by biasing the dominant form of synaptic plasticity away from LTP and toward LTD in CA2.

Lineage Tracing of RGS5-CreER-Labeled Cells in Long Bones During Homeostasis and Injury

Regulator of G protein signaling 5 (RGS5) is a GTPase activator for heterotrimeric G-protein α-subunits, shown to be a marker of pericytes. Bone marrow stromal cell population (BMSCs) is heterogeneous. Populations of mesenchymal progenitors, cells supportive of hematopoiesis, and stromal cells regulating bone remodeling have been recently identified. Periosteal and bone marrow mesenchymal stem cells (MSCs) are participating in fracture healing, but it is difficult to distinguish the source of cells within the callus. Considering that perivascular cells exert osteoprogenitor potential, we generated an RGS5 transgenic mouse model (Rgs5-CreER) which when crossed with Ai9 reporter animals (Rgs5/Tomato), is suitable for lineage tracing during growth and post-injury. Flow cytometry analysis and histology confirmed the presence of Rgs5/Tomato+ cells within CD31+ endothelial, CD45+ hematopoietic, and CD31-CD45- mesenchymal/perivascular cells. A tamoxifen chase showed expansion of Rgs5/Tomato+ cells expressing osterix within the trabeculae positioned between mineralized matrix and vasculature. Long-term chase showed proportion of Rgs5/Tomato+ cells contributes to mature osteoblasts expressing osteocalcin. Following femoral fracture, Rgs5/Tomato+ cells are observed around newly formed bone within the BM cavity and expressed osterix and osteocalcin, while contribution within periosteum was low and limited to fibroblastic callus with very few positive chondrocytes. In addition, BM injury model confirmed that RGS5-Cre labels population of BMSCs expands during injury and participates in osteogenesis. Under homeostatic conditions, lineage-traced RGS5 cells within the trabecular area demonstrate osteoprogenitor capacity that in an injury model contributes to new bone formation primarily within the BM niche.

Functional Assessment of Cancer-Linked Mutations in Sensitive Regions of Regulators of G Protein Signaling Predicted by Three-Dimensional Missense Tolerance Ratio Analysis

Regulators of G protein signaling (RGS) proteins modulate G protein-coupled receptor (GPCR) signaling by acting as negative regulators of G proteins. Genetic variants in RGS proteins are associated with many diseases, including cancers, although the impact of these mutations on protein function is uncertain. Here we analyze the RGS domains of 15 RGS protein family members using a novel bioinformatic tool that measures the missense tolerance ratio (MTR) using a three-dimensional (3D) structure (3DMTR). Subsequent permutation analysis can define the protein regions that are most significantly intolerant (P < 0.05) in each dataset. We further focused on RGS14, RGS10, and RGS4. RGS14 exhibited seven significantly tolerant and seven significantly intolerant residues, RGS10 had six intolerant residues, and RGS4 had eight tolerant and six intolerant residues. Intolerant and tolerant-control residues that overlap with pathogenic cancer mutations reported in the COSMIC cancer database were selected to define the functional phenotype. Using complimentary cellular and biochemical approaches, proteins were tested for effects on GPCR-Gα activation, Gα binding properties, and downstream cAMP levels. Identified intolerant residues with reported cancer-linked mutations RGS14-R173C/H and RGS4-K125Q/E126K, and tolerant RGS14-S127P and RGS10-S64T resulted in a loss-of-function phenotype in GPCR-G protein signaling activity. In downstream cAMP measurement, tolerant RGS14-D137Y and RGS10-S64T and intolerant RGS10-K89M resulted in change of function phenotypes. These findings show that 3DMTR identified intolerant residues that overlap with cancer-linked mutations cause phenotypic changes that negatively impact GPCR-G protein signaling and suggests that 3DMTR is a potentially useful bioinformatics tool for predicting functionally important protein residues. SIGNIFICANCE STATEMENT: Human genetic variant/mutation information has expanded rapidly in recent years, including cancer-linked mutations in regulator of G protein signaling (RGS) proteins. However, experimental testing of the impact of this vast catalogue of mutations on protein function is not feasible. We used the novel bioinformatics tool three-dimensional missense tolerance ratio (3DMTR) to define regions of genetic intolerance in RGS proteins and prioritize which cancer-linked mutants to test. We found that 3DMTR more accurately classifies loss-of-function mutations in RGS proteins than other databases thereby offering a valuable new research tool.

The therapeutic potential of targeting cardiac RGS4

G protein-coupled receptors (GPCRs) play pivotal roles in regulation of cardiac function and homeostasis. To function properly, every cell needs these receptors to be stimulated only when a specific extracellular stimulus is present, and to be silenced the moment that stimulus is removed. The regulator of G protein signaling (RGS) proteins are crucial for the latter to occur at the cell membrane, where the GPCR normally resides. Perturbations in both activation and termination of G protein signaling underlie numerous heart pathologies. Although more than 30 mammalian RGS proteins have been identified, each RGS protein seems to interact only with a specific set of G protein subunits and GPCR types/subtypes in any given tissue or cell type, and this applies to the myocardium as well. A large number of studies have provided substantial evidence for the roles various RGS proteins expressed in cardiomyocytes play in cardiac physiology and heart disease pathophysiology. This review summarizes the current understanding of the functional roles of cardiac RGS proteins and their implications for the treatment of specific heart diseases, such as heart failure and atrial fibrillation. We focus on cardiac RGS4 in particular, since this isoform appears to be selectively (among the RGS protein family) upregulated in human heart failure and is also the target of ongoing drug discovery efforts for the treatment of a variety of diseases.

ATF3 Modulates the Proliferation, Migration, and Apoptosis of Synovial Fibroblasts after Arthroscopy by Promoting RGS1 Transcription

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease involving both cartilage and synovium. Activating transcription factor 3 (ATF3) and regulator of G protein signaling 1 (RGS1) have been reported to be up-regulated in OA. However, little is known regarding the relationship between these two genes and the mechanism of this relationship in OA development. Therefore, the present study explores the mechanism of ATF3-mediated RGS1 in the proliferation, migration, and apoptosis of synovial fibroblasts.

METHODS

After the OA cell model was constructed with TGF-β1 induction, human fibroblast-like synoviocytes (HFLSs) were transfected with ATF3 shRNA or RGS1 shRNA alone or co-transfected with ATF3 shRNA and pcDNA3.1-RGS1. Then, proliferation, migration, apoptosis, and the expression of ATF3, RGS1, α-SMA, BCL-2, caspase3, and cleaved-caspase3 were measured. Meanwhile, the potential relationship between ATF3 and RGS1 was predicted and validated.

RESULTS AND DISCUSSION

Analysis of the GSE185059 dataset suggested that RGS1 was up-regulated in OA synovial fluid exosomes. Moreover, ATF3 and RGS1 were both highly expressed in TGF-β1-induced HFLSs. Transfection of ATF3 shRNA or RGS1 shRNA significantly reduced proliferation and migration and promoted apoptosis of TGF- β1-induced HFLSs. Mechanistically, ATF3 bound to the RGS1 promoter and elevated RGS1 expression. Silencing ATF3 repressed proliferation and migration and enhanced apoptosis of TGF-β1-induced HFLSs by down-regulating RGS1.

CONCLUSION

ATF3 binds to the RGS1 promoter and enhances RGS1 expression to accelerate cell proliferation and block cell apoptosis in TGF-β1-induced synovial fibroblasts.

Gene expression meta-analysis in patients with schizophrenia reveals up-regulation of RGS2 and RGS16 in Brodmann Area 10

Regulator of G-protein signalling (RGS) proteins inhibit signalling by G-protein-coupled receptors (GPCRs). GPCRs mediate the functions of several important neurotransmitters and serve as targets of many anti-psychotics. RGS2, RGS4, RGS5 and RGS16 are located on chromosome 1q23.3-31, a locus found to be associated with schizophrenia. Although previous gene expression analysis detected down-regulation of RGS4 expression in brain samples of patients with schizophrenia, the results were not consistent. In the present study, we performed a systematic meta-analysis of differential RGS2, RGS4, RGS5 and RGS16 expression in Brodmann Area 10 (BA10) samples of patients with schizophrenia and from healthy controls. Two microarray datasets met the inclusion criteria (overall, 41 schizophrenia samples and 38 controls were analysed). RGS2 and RGS16 were found to be up-regulated in BA10 samples of individuals with schizophrenia, whereas no differential expression of RGS4 and RGS5 was detected. Analysis of dorso-lateral prefrontal cortex samples of the CommonMind Consortium (258 schizophrenia samples vs. 279 controls) further validated the results. Given their central role in inactivating G-protein-coupled signalling pathways, our results suggest that differential gene expression might lead to enhanced inactivation of G-protein signalling in schizophrenia. This, in turn, suggests that additional studies are needed to further explore the consequences of the differential expression we detected, this time at the protein and functional levels.

Fatty acid metabolism is related to the immune microenvironment changes of gastric cancer and RGS2 is a new tumor biomarker

Background

Alterations in lipid metabolism promote tumor progression. However, the role of lipid metabolism in the occurrence and development of gastric cancer have not been fully clarified.

Method

Here, genes that are related to fatty acid metabolism and differentially-expressed between normal and gastric cancer tissues were identified in the TCGA-STAD cohort. The intersection of identified differentially-expressed genes with Geneset was determined to obtain 78 fatty acid metabolism-related genes. The ConsensusClusterPlus R package was used to perform differentially-expressed genes, which yielded divided two gastric cancer subtypes termed cluster 1 and cluster 2.

Results

Patients in cluster 2 was found to display poorer prognosis than patients in cluster 1. Using machine learning method to select 8 differentially expressed genes among subtypes to construct fatty acid prognostic risk score model (FARS), which was found to display good prognostic efficacy. We also identified that certain anticancer drugs, such as bortezomib, elesclomol, GW843682X, and nilotinib, showed significant sensitivity in the high FARS score group. RGS2 was selected as the core gene upon an analysis of the gastric cancer single-cell, and Western blotting and immunofluorescence staining results revealed high level of expression of this gene in gastric cancer cells. The results of immunohistochemical staining showed that a large amount of RGS2 was deposited in the stroma in gastric cancer. A pan-cancer analysis also revealed a significant association of RGS2 with TMB, TIDE, and CD8+ T-cell infiltration in other cancer types as well. RGS2 may thus be studied further as a new target for immunotherapy in future studies on gastric cancer.

Conclusion

In summary, the FARS model developed here enhances our understanding of lipid metabolism in the TME in gastric cancer, and provides a theoretical basis for predicting tumor prognosis and clinical treatment.

Arabidopsis MPK3 and MPK6 regulates D-glucose signaling and interacts with G-protein, RGS1

Sugar as a signaling molecule has attracted lots of attention. Even though several kinases have been shown to play a crucial role in the sugar signaling and response to exogenous D-glucose (Glc), the information on the involvement of MAP kinase cascade in sugar signaling has remain largely unexplored. In this report we demonstrate that MAP kinase signaling is essential for sensitivity to higher concentrations of D-Glc in Arabidopsis. We found that D-Glc activates MAP kinases, MPK3 and MPK6 in a concentration and time-dependent manner. The mutants of mpk3 and mpk6 display hyposensitivity to 6% D-Glc during seed germination, cotyledon greening and root growth. Interestingly, the altered sensitivity to increased D-Glc is severely enhanced by addition of 1% Sucrose in the media. Our study also deciphered the role of one of the Glc sensor proteins, RGS1 that interacts and gets phosphorylated at its C-terminal domain by MPK3 and MPK6. Overall our study provides a new insight on the involvement of MAP kinases in association with G-proteins that might regulate sugar signaling and sugar responsive growth and development in Arabidopsis.

Cardiometabolic Consequences of Deleting the Regulator of G protein Signaling-2 (Rgs2) From Cells Expressing Agouti-Related Peptide or the ANG (Angiotensin) II Type 1A Receptor in Mice

BACKGROUND

RGS (regulator of G protein signaling) family members catalyze the termination of G protein signaling cascades. Single nucleotide polymorphisms in the RGS2 gene in humans have been linked to hypertension, preeclampsia, and anxiety disorders. Mice deficient for Rgs2 (Rgs2Null) exhibit hypertension, anxiety, and altered adipose development and function.

METHODS

To study cell-specific functions of RGS2, a novel gene-targeted mouse harboring a conditional allele for the Rgs2 gene (Rgs2Flox) was developed. These mice were bred with mice expressing Cre-recombinase via the Agouti-related peptide locus (Agrp-Cre) to cause deletion of Rgs2 from all cells expressing Agrp (Rgs2Agrp-KO), or a novel transgenic mouse expressing Cre-recombinase via the ANG (angiotensin) type 1A receptor (Agtr1a/ AT1A) promoter encoded in a bacterial artificial chromosome (BAC-AT1A-Cre) to delete Rgs2 in all Agtr1a-expressing cells (Rgs2AT1A-KO).

RESULTS

Whereas Rgs2Flox, Rgs2Agrp-KO, and BAC-AT1A-Cre mice exhibited normal growth and survival, Rgs2AT1A-KO exhibited pre-weaning lethality. Relative to littermates, Rgs2Agrp-KO exhibited reduced fat gains when maintained on a high fat diet, associated with increased energy expenditure. Similarly, surviving adult Rgs2AT1A-KO mice also exhibited increased energy expenditure. Surprisingly, given the hypertensive phenotype previously reported for Rgs2Null mice and evidence supporting a role for RGS2 in terminating AT1A signaling in various cell types, Rgs2AT1A-KO mice exhibited normal blood pressure, ingestive behaviors, and renal functions, both before and after chronic infusion of ANG (490 ng/kg/min, sc).

CONCLUSIONS

These results demonstrate the development of a novel mouse with conditional expression of Rgs2 and illustrate the role of Rgs2 within selected cell types for cardiometabolic control.

RGS3 and IL1RAPL1 missense variants implicate defective neurotransmission in early-onset inherited schizophrenias

BACKGROUND

Schizophrenia is characterized by hallucinations, delusions and disorganized behaviour. Recessive or X-linked transmissions are rarely described for common psychiatric disorders. We examined the genetics of psychosis to identify rare large-effect variants in patients with extreme schizophrenia.

METHODS

We recruited 2 consanguineous families, each with patients affected by early-onset, severe, treatment-resistant schizophrenia. We performed exome sequencing for all participants. We checked variant rarity in public databases and with ethnically matched controls. We performed in silico analyses to assess the effects of the variants on proteins.

RESULTS

Structured clinical evaluations supported diagnoses of schizophrenia in all patients and phenotypic absence in the unaffected individuals. Data analyses identified multiple variants. Only 1 variant per family was predicted as pathogenic by prediction tools. A homozygous c.649C > T:p.(Arg217Cys) variant in RGS3 and a hemizygous c.700A > G:p.(Thr234Ala) variant in IL1RAPL1 affected evolutionary conserved amino acid residues and were the most likely causes of phenotype in the patients of each family. Variants were ultra-rare in publicly available databases and absent from the DNA of 400 ethnically matched controls. RGS3 is implicated in modulating sensory behaviour in Caenorhabditis elegans. Variants of IL1RAPL1 are known to cause nonsyndromic X-linked intellectual disability with or without human behavioural dysfunction.

LIMITATIONS

Each variant is unique to a particular family's patients, and findings may not be replicated.

CONCLUSION

Our work suggests that some rare variants may be involved in causing inherited psychosis or schizophrenia. Variant-specific functional studies will elucidate the pathophysiology relevant to schizophrenias and motivate translation to personalized therapeutics.

RGS12 polarizes the GPSM2-GNAI complex to organize and elongate stereocilia in sensory hair cells

Inhibitory G proteins (GNAI/Gαi) bind to the scaffold G protein signaling modulator 2 (GPSM2) to form a conserved polarity complex that regulates cytoskeleton organization. GPSM2 keeps GNAI in a guanosine diphosphate (GDP)-bound state, but how GPSM2-GNAI is generated or relates to heterotrimeric G protein signaling remains unclear. We find that RGS12, a GTPase-activating protein (GAP), is required to polarize GPSM2-GNAI at the hair cell apical membrane and to organize mechanosensory stereocilia in rows of graded heights. Accordingly, RGS12 and the guanine nucleotide exchange factor (GEF) DAPLE are asymmetrically co-enriched at the hair cell apical junction, and Rgs12 mouse mutants are deaf. GPSM2 and RGS12 share GoLoco motifs that stabilize GNAI(GDP), and GPSM2 outcompetes RGS12 to bind GNAI. Our results suggest that polarized GEF/GAP junctional activity might dissociate heterotrimeric G proteins, generating free GNAI(GDP) for GPSM2 at the adjacent apical membrane. GPSM2-GNAI(GDP), in turn, imparts asymmetry to the forming stereocilia to enable sensory function in hair cells.

Clinical and molecular implications of RGS2 promoter genetic variation in severe asthma

BACKGROUND

Regulator of G protein signaling (RGS) 2 terminates bronchoconstrictive Gαq signaling; murine RGS2 knockout demonstrate airway hyperresponsiveness. While RGS2 promoter variants rs2746071 and rs2746072 associate with a clinical mild asthma phenotype, their impact on human airway smooth muscle (HASM) contractility and asthma severity outcomes is unknown.

OBJECTIVE

We sought to determine whether reductions in RGS2 expression seen with these 2 RGS2 promoter variants augment HASM contractility and associate with an asthma severity phenotype.

METHODS

We transfected HASM with a range of RGS2-specific small interfering RNA (siRNA) concentrations and determined RGS2 protein expression by Western blot analysis and intracellular calcium flux induced by histamine (a Gαq-coupled H1 receptor bronchoconstrictive agonist). We conducted regression-based genotype association analyses of RGS2 variants from 611 patients from the National Heart, Lung, and Blood Institute Severe Asthma Research Program 3.

RESULTS

RGS2-specific siRNA caused dose-dependent increases in histamine-stimulated bronchoconstrictive intracellular calcium signaling (2-way ANOVA, P < .0001) with a concomitant decrease in RGS2 protein expression. RGS2-specific siRNA did not affect Gαq-independent ionomycin-induced intracellular calcium signaling (P = .42). The minor allele frequency of rs2746071 and rs2746072 was 0.46 and 0.28 among African American/non-Hispanic Black patients and was 0.28 and 0.27 among non-Hispanic White patients, among whom these single nucleotide polymorphisms were in stronger linkage disequilibrium (r2 = 0.97). Among non-Hispanic White patients, risk allele homozygotes for rs2746072 and rs2746071 each had nearly 2-fold greater asthma exacerbation rates relative to alternative genotypes with wild-type alleles (Padditive = 2.86 × 10-5/Precessive = 5.22 × 10-6 and Padditive = 3.46 × 10-6/Precessive = 6.74 × 10-7, respectively) at baseline, which was confirmed by prospective longitudinal exacerbation data.

CONCLUSION

RGS2 promoter variation associates with a molecular and clinical phenotype characterized by enhanced bronchoconstrictive stimulation in vitro and higher asthma exacerbations rates in non-Hispanic White patients.

Key molecules associated with thyroid carcinoma prognosis: A study based on transcriptome sequencing and GEO datasets

Background

Thyroid carcinoma (THCA) has a low mortality rate, but its incidence has been rising over the years. We need to pay attention to its progression and prognosis. In this study, a transcriptome sequencing analysis and bioinformatics methods were used to screen key genes associated with THCA development and analyse their clinical significance and diagnostic value.

Methods

We collected 10 pairs of THCA tissues and noncancerous tissues, these samples were used for transcriptome sequencing to identify disordered genes. The gene expression profiles were obtained from the Gene Expression Omnibus (GEO) database. Comprehensive analysis of thyroid clinicopathological data using The Cancer Genome Atlas (TCGA). R software was used to carry out background correction, normalization and log2 conversion. We used quantitative real-time PCR (qRT–PCR) and Western blot to determine differentially expressed genes (DEGs) expression in samples. We integrated the DEGs expression, clinical features and progression-free interval (PFI). The related functions and immune infiltration degree were established by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Set Enrichment Analysis (GSEA), and single-sample Gene Set Enrichment Analysis (ssGSEA). The UALCAN database was used to analyse the methylation level.

Results

We evaluated DEGs between normal tissue and cancer. Three genes were identified: regulator of G protein signaling 8 (RGS8), diacylglycerol kinase iota (DGKI) and oculocutaneous albinism II (OCA2). The mRNA and protein expression levels of RGS8, DGKI and OCA2 in normal tissues were higher than those in THCA tissues. Better survival outcomes were associated with higher expression of RGS8 (HR=0.38, P=0.001), DGKI (HR=0.52, P=0.022), and OCA2 (HR=0.41, P=0.003). The GO analysis, KEGG analysis and GSEA proved that the coexpressed genes of RGS8, DGKI and OCA2 were related to thyroid hormone production and peripheral downstream signal transduction effects. The expression levels of RGS8, DGKI and OCA2 were linked to the infiltration of immune cells such as DC cells. The DNA methylation level of OCA2 in cancer tissues was higher than that in the normal samples.

Conclusions

RGS8, DGKI and OCA2 might be promising prognostic molecular markers in patients with THCA and reveal the clinical significance of RGS8, DGKI and OCA2 in THCA.

Implications of regulator of G-protein signaling 5 expression in the pathogenesis of primary and secondary hyperparathyroidism

OBJECTIVE

To study the protein and mRNA expressions of regulator of G-protein signaling 5 (RGS5) in the pathogenesis of hyperparathyroidism.

METHODS

The expression of RGS5 protein in 20 primary hyperparathyroidism (PHPT), 31 secondary hyperparathyroidism (SHPT), and 20 control cases were studied by immunohistochemistry (IHC). The expression of RGS5 mRNA in 15 PHPT, 102 SHPT, and 7 normal parathyroid tissue were measured by quantitative real-time PCR (qRT-PCR) method.

RESULTS

The expressions of RGS5 in PHPT tissues were significantly higher than that in SHPT and normal parathyroid tissues (P < 0.05). While the differences in RGS5 protein expressions between SHPT and respective control samples were not statistically significant (P > 0.05). Likewise, the RGS5 mRNA expression in PHPT was significantly higher than that in SHPT (P < 0.05) and normal parathyroid (P < 0.05) samples. In a similar line, the differences in RGS5 gene expressions between SHPT and control tissues were not statistically significant (P > 0.05).

CONCLUSIONS

The characteristic RGS5 protein and mRNA levels in hyperparathyroidism might be helpful in discovering the pathomechanism of hyperparathyroidism and novel therapeutic targets as well.

Regulator of G protein signaling 2 is inhibited by hypoxia-inducible factor-1α/E1A binding protein P300 complex upon hypoxia in human preeclampsia

BACKGROUND

Preeclampsia is a pregnancy-related complication that causes maternal and fetal mortality. Despite extensive studies showing the role of hypoxia in preeclampsia progression, the specific mechanism remains unclear. The purpose of this study was to explore the possible mechanism underlying hypoxia in preeclampsia.

METHODS

Human trophoblast-like JEG-3 cell line was used to investigate the molecular mechanisms underlying hypoxia contribution to preeclampsia and the expression correlation of key molecules was examined in human placental tissues. Methods include JEG-3 cell culture and hypoxia induction, RNA isolation and quantitative real-time PCR, transient transfection and dual-luciferase assay, western blot, immunoprecipitation, immunofluorescence staining, cell proliferation assay, chromatin immunoprecipitation assay, obtainment of human placental tissue sample and immunohistochemistry staining.

RESULTS

Hypoxia-Inducible Factor-1α is up-regulated in clinical preeclampsia samples, where Regulator of G Protein Signaling 2 is down-regulated. Mechanistically, Hypoxia-Inducible Factor-1α is induced in response to hypoxia, which up-regulates E1A binding protein P300 expression and thereby forms a Hypoxia-Inducible Factor-1α/E1A binding protein P300 protein-protein complex that binds to the promoter of gene Regulator of G Protein Signaling 2 and subsequently inhibits the transcription of Regulator of G Protein Signaling 2, possibly contributing to the preeclampsia development. In addition, the expression of E1A binding protein P300 is increased in preeclampsia samples, and the expression of Regulator of G Protein Signaling 2 in preeclamptic placentas inversely correlates with the levels of E1A binding protein P300.

CONCLUSION

Our findings may provide novel insights into understanding the molecular pathogenesis of preeclampsia and may be a prognostic biomarker and therapeutic target for preeclampsia.

Regulator of G-Protein Signaling-4 Attenuates Cardiac Adverse Remodeling and Neuronal Norepinephrine Release-Promoting Free Fatty Acid Receptor FFAR3 Signaling

Propionic acid is a cell nutrient but also a stimulus for cellular signaling. Free fatty acid receptor (FFAR)-3, also known as GPR41, is a Gi/o protein-coupled receptor (GPCR) that mediates some of the propionate's actions in cells, such as inflammation, fibrosis, and increased firing/norepinephrine release from peripheral sympathetic neurons. The regulator of G-protein Signaling (RGS)-4 inactivates (terminates) both Gi/o- and Gq-protein signaling and, in the heart, protects against atrial fibrillation via calcium signaling attenuation. RGS4 activity is stimulated by β-adrenergic receptors (ARs) via protein kinase A (PKA)-dependent phosphorylation. Herein, we examined whether RGS4 modulates cardiac FFAR3 signaling/function. We report that RGS4 is essential for dampening of FFAR3 signaling in H9c2 cardiomyocytes, since siRNA-mediated RGS4 depletion significantly enhanced propionate-dependent cAMP lowering, Gi/o activation, p38 MAPK activation, pro-inflammatory interleukin (IL)-1β and IL-6 production, and pro-fibrotic transforming growth factor (TGF)-β synthesis. Additionally, catecholamine pretreatment blocked propionic acid/FFAR3 signaling via PKA-dependent activation of RGS4 in H9c2 cardiomyocytes. Finally, RGS4 opposes FFAR3-dependent norepinephrine release from sympathetic-like neurons (differentiated Neuro-2a cells) co-cultured with H9c2 cardiomyocytes, thereby preserving the functional βAR number of the cardiomyocytes. In conclusion, RGS4 appears essential for propionate/FFAR3 signaling attenuation in both cardiomyocytes and sympathetic neurons, leading to cardioprotection against inflammation/adverse remodeling and to sympatholysis, respectively.

Filling in the gaps: SNX-RGS proteins as multiorganelle tethers

SNX-RGS proteins are molecular tethers localized to multiple interorganelle contact sites that exhibit roles in cellular metabolism. Here, we highlight recent findings on these proteins and discuss their emerging roles in metabolism, human disease, and lipid trafficking.

RGS14 regulates PTH- and FGF23-sensitive NPT2A-mediated renal phosphate uptake via binding to the NHERF1 scaffolding protein

Phosphate homeostasis, mediated by dietary intake, renal absorption, and bone deposition, is incompletely understood because of the uncharacterized roles of numerous implicated protein factors. Here, we identified a novel role for one such element, regulator of G protein signaling 14 (RGS14), suggested by genome-wide association studies to associate with dysregulated Pi levels. We show that human RGS14 possesses a carboxy-terminal PDZ ligand required for sodium phosphate cotransporter 2a (NPT2A) and sodium hydrogen exchanger regulatory factor-1 (NHERF1)-mediated renal Pi transport. In addition, we found using isotope uptake measurements combined with bioluminescence resonance energy transfer assays, siRNA knockdown, pull-down and overlay assays, and molecular modeling that secreted proteins parathyroid hormone (PTH) and fibroblast growth factor 23 inhibited Pi uptake by inducing dissociation of the NPT2A-NHERF1 complex. PTH failed to affect Pi transport in cells expressing RGS14, suggesting that it suppresses hormone-sensitive but not basal Pi uptake. Interestingly, RGS14 did not affect PTH-directed G protein activation or cAMP formation, implying a postreceptor site of action. Further pull-down experiments and direct binding assays indicated that NPT2A and RGS14 bind distinct PDZ domains on NHERF1. We showed that RGS14 expression in human renal proximal tubule epithelial cells blocked the effects of PTH and fibroblast growth factor 23 and stabilized the NPT2A-NHERF1 complex. In contrast, RGS14 genetic variants bearing mutations in the PDZ ligand disrupted RGS14 binding to NHERF1 and subsequent PTH-sensitive Pi transport. In conclusion, these findings identify RGS14 as a novel regulator of hormone-sensitive Pi transport. The results suggest that changes in RGS14 function or abundance may contribute to the hormone resistance and hyperphosphatemia observed in kidney diseases.

Downregulation of miR-26 promotes invasion and metastasis via targeting interleukin-22 in cutaneous T-cell lymphoma

It has been reported that certain microRNAs (miRNA) are associated with the pathogenesis of lymphoma. We have previously demonstrated that histone deacetylase inhibitors restore tumor-suppressive miRNAs, such as miR-16, miR-29, miR-150, and miR-26, in advanced cutaneous T-cell lymphoma (CTCL). Among these, the function of miR-26 remains unclear. In this study, we aimed to reveal the function of miR-26 in CTCL oncogenesis. First, we confirmed that the miR-26 family was markedly dysregulated in CTCL cell lines and primary samples. In vivo analysis using miR-26a-transduced CTCL cells injected into immunodeficient NOG mice demonstrated the significant prolonged survival of the mice, suggesting that the miRNA had a tumor-suppressive function. We performed gene expression assays and identified 12 candidate miR-26 targets, namely RGS13, FAM71F1, OAF, SNX21, CDH2, PTPLB, IL22, DNAJB5, CASZ1, CACNA1C, MYH10, and CNR1. Among these, IL22 was the most likely candidate target because the IL-22-STAT3-CCL20-CCR6 cascade is associated with tumor invasion and metastasis of advanced CTCL. In vitro analysis of IL22 and IL22RA knockdown and miR-26 transduction demonstrated inhibited CTCL cell migration. In particular, IL22 knockdown induced cell apoptosis. Finally, we conducted in vivo inoculation analysis of mice injected with shIL22-transfected CTCL cells, and found no tumor invasion or metastasis in the inoculated mice, although the control mice showed multiple tumor invasions and metastases. These results, along with our previous data, demonstrated that miR-26 is a tumor suppressor that is associated with tumor invasion and the metastasis of advanced CTCL by regulating the IL-22-STAT3-CCL20 cascade. Therefore, a IL-22-targeting therapy could be a novel therapeutic strategy for advanced CTCL.

Effect of Regulator of G Protein Signaling Proteins on Bone

Regulator of G protein signaling (RGS) proteins are critical negative molecules of G protein-coupled receptor (GPCR) signaling, which mediates a variety of biological processes in bone homeostasis and diseases. The RGS proteins are divided into nine subfamilies with a conserved RGS domain which plays an important role in regulating the GTPase activity. Mutations of some RGS proteins change bone development and/or metabolism, causing osteopathy. In this review, we summarize the recent findings of RGS proteins in regulating osteoblasts, chondrocytes, and osteoclasts. We also highlight the impacts of RGS on bone development, bone remodeling, and bone-related diseases. Those studies demonstrate that RGS proteins might be potential drug targets for bone diseases.

Role of RGS2 in sevoflurane-induced cognitive dysfunction in aged rats

After undergoing inhalation anesthesia, some patients, especially elderly patients, experience postoperative cognitive dysfunction, such as personality changes and memory impairment. In the present study, 20-month-old rats were randomly allocated to sevoflurane (Sevo group) and control groups (Con group), and they inhaled 3% sevoflurane or 40% oxygen for 8 hours, respectively. The Morris water maze test found that the cognitive function of rats in the Sevo group were significantly different on 1d and 3d after anesthesia than that of rats in the Con group. The expression of RGS2 mRNA and protein in hippocampus of Sevo group was lower compared to the Con group, while Ca^{2 +} was higher than con group. The expression of CaM and CaMK II in Sevo group was higher compared to the Con group. We found that Bcl-2 reduced, but the expression of Bax and Caspase-3 increased, indicating that apoptosis of hippocampal neurons was increased after sevoflurane inhalation. Both the expression of NGF and BDNF was depressed in the Sevo group. After continuous inhalation of 3% sevoflurane for 8h, the expression of RGS2 in the hippocampi of aged rats is down regulated. RGS2 may be an important factor that leads to cognitive dysfunction in rats.

Single-Cell Transcriptome Analysis Reveals RGS1 as a New Marker and Promoting Factor for T-Cell Exhaustion in Multiple Cancers

T-cell exhaustion is one of the main reasons of tumor immune escape. Using single-cell transcriptome data of CD8+ T cells in multiple cancers, we identified different cell types, in which Pre_exhaust and exhausted T cells participated in negative regulation of immune system process. By analyzing the coexpression network patterns and differentially expressed genes of Pre_exhaust, exhausted, and effector T cells, we identified 35 genes related to T-cell exhaustion, whose high GSVA scores were associated with significantly poor prognosis in various cancers. In the differentially expressed genes, RGS1 showed the greatest fold change in Pre_exhaust and exhausted cells of three cancers compared with effector T cells, and high expression of RGS1 was also associated with poor prognosis in various cancers. Additionally, RGS1 protein was upregulated significantly in tumor tissues in the immunohistochemistry verification. Furthermore, RGS1 displayed positive correlation with the 35 genes, especially highly correlated with PDCD1, CTLA4, HAVCR2, and TNFRSF9 in CD8+ T cells and cancer tissues, indicating the important roles of RGS1 in CD8+ T-cell exhaustion. Considering the GTP-hydrolysis activity of RGS1 and significantly high mRNA and protein expression in cancer tissues, we speculated that RGS1 potentially mediate the T-cell retention to lead to the persistent antigen stimulation, resulting in T-cell exhaustion. In conclusion, our findings suggest that RGS1 is a new marker and promoting factor for CD8+ T-cell exhaustion and provide theoretical basis for research and immunotherapy of exhausted cells.

RGS10 Reduces Lethal Influenza Infection and Associated Lung Inflammation in Mice

Seasonal influenza epidemics represent a significant global health threat. The exacerbated immune response triggered by respiratory influenza virus infection causes severe pulmonary damage and contributes to substantial morbidity and mortality. Regulator of G-protein signaling 10 (RGS10) belongs to the RGS protein family that act as GTPase activating proteins for heterotrimeric G proteins to terminate signaling pathways downstream of G protein-coupled receptors. While RGS10 is highly expressed in immune cells, in particular monocytes and macrophages, where it has strong anti-inflammatory effects, its physiological role in the respiratory immune system has not been explored yet. Here, we show that Rgs10 negatively modulates lung immune and inflammatory responses associated with severe influenza H1N1 virus respiratory infection in a mouse model. In response to influenza A virus challenge, mice lacking RGS10 experience enhanced weight loss and lung viral titers, higher mortality and significantly faster disease onset. Deficiency of Rgs10 upregulates the levels of several proinflammatory cytokines and chemokines and increases myeloid leukocyte accumulation in the infected lung, markedly neutrophils, monocytes, and inflammatory monocytes, which is associated with more pronounced lung damage. Consistent with this, influenza-infected Rgs10-deficent lungs contain more neutrophil extracellular traps and exhibit higher neutrophil elastase activities than wild-type lungs. Overall, these findings propose a novel, in vivo role for RGS10 in the respiratory immune system controlling myeloid leukocyte infiltration, viral clearance and associated clinical symptoms following lethal influenza challenge. RGS10 also holds promise as a new, potential therapeutic target for respiratory infections.

miR-183-5p Aggravates Breast Cancer Development via Mediation of RGS2

This study mainly explores how miR-183-5p pertains to breast cancer (BC) development. Functional assays were employed to test impacts of miR-183-5p in this cancer. Targeting between RGS2 and miR-183-5p was examined with dual-luciferase assay, and how their interaction pertains to cancer progression was further unraveled. miR-183-5p level was noticeably high in cancer tissue/cells. Overexpressing miR-183-5p could remarkably deteriorate cancer progression. The regulatory gene RGS2 levels was markedly low in BC, and two genes we researched were negatively correlated. It was uncovered by rescue assay that miR-183-5p/RGS2 axis mediated tumor-relevant behaviors in BC. Altogether, miR-183-5p aggravates BC development via mediation of RGS2. miR-183-5p supplies a promising target for BC therapy.

Association between RGS4 gene polymorphisms and schizophrenia: A protocol for systematic review and meta-analysis

BACKGROUND

Schizophrenia is a complex brain disorder, the pathogenesis of which remains unclear. Regulator of G-protein signaling 4 is regarded as a candidate gene for schizophrenia risk. The association between the regulator of G-protein signaling 4 gene and the risk of schizophrenia is complicated and controversial, thus, an updated meta-analysis is needed.

METHODS

A search strategy using Medical Subject Headings was developed in English (PubMed, SZGene) and Chinese (CNKI, Wanfang, and Weipu) databases. Inclusion and exclusion criteria were used to screen for eligible studies. Parameters, such as P value of Hardy-Weinberg equilibrium, odds ratios, 95% confidence intervals, P values of association, heterogeneity (Ph), and publication bias, were analyzed by the Stata software using a random effects model. Subgroup analyses were performed to detect heterogeneity.

RESULTS

There were 15 articles regarding rs10917670 (8046 cases and 8837 controls), 16 regarding rs951436 (8990 cases and 10,568 controls), 15 regarding rs951439 (7995 cases and 8646 controls), 15 regarding rs2661319 (8320 cases and 9440 controls), and 4 regarding rs10759 (2752 cases and 2866 controls). The frequencies of rs10917670 and rs951439 were not significantly different between the case and control groups (P > .05). As shown by the East Asian and hospital-based subgroup analyses, the genotype TT of rs951436 might be related to the risk of schizophrenia. The genotypes CC + CT of rs2661319 and CC + CA of rs10759 were statistically different between the 2 groups, and the East Asian population contributed to these differences.

CONCLUSION

The genotypes CC + CT of rs2661319 and CC + CA of rs10759 might be associated with the risk of schizophrenia.

Integration of NRP1, RGS5, and FOXM1 expression, and tumour necrosis, as a postoperative prognostic classifier based on molecular subtypes of clear cell renal cell carcinoma

Molecular mechanisms of progression of clear cell renal cell carcinoma (ccRCC) have been proven with recent genomic or transcriptional analyses. However, it is still difficult to apply these analyses to daily clinical practice owing to economical and practical issues. Here, we established a pathology-based, postoperative prognostic classification based on the well-validated transcriptional classifier, ClearCode34, in ccRCC. A total of 342 cases with available tissue were identified and randomly allocated into a discovery cohort (n = 138) and a validation cohort (n = 204). Levels of mRNA were quantified using a nCounter Digital Analyzer, and the ccA/ccB subtypes were determined. Histological and immunohistochemistry (IHC) analyses were subsequently performed to establish a pathology-based classification based on the mRNA levels. Finally, the prognostic ability of the new classifier was evaluated in both the discovery and validation cohorts. Of 138 cases in the discovery cohort, 78 (56.5%) and 60 (43.5%) were assigned to the ccA and ccB subtypes, respectively. Proangiogenic genes, neuropilin 1 (NRP1) and regulator of G protein signalling 5 (RGS5), were especially overexpressed in all ccRCC samples and were enriched in ccA-assigned tumours. Histologically, tumour necrosis and the sarcomatoid feature were associated with the ccB subtype. In IHC analyses, expression of NRP1, RGS5, and forkhead box M1 (FOXM1), an epithelial-mesenchymal transition-related factor, significantly correlated with the ccA/ccB subtypes. Combining these three IHC factors and tumour necrosis, we developed the IHC/histology-based classifier, which showed good concordance with the ClearCode34 classifier with an accuracy of 0.80. The established classification significantly stratified relapse-free, cancer-specific, and overall survival rates in both the discovery and validation cohorts. The novel molecular pathology classifier integrating NRP1, RGS5, FOXM1, and tumour necrosis may enable the stratification of oncological outcomes for patients with ccRCC undergoing resection surgery.

The G protein signaling regulator RGS3 enhances the GTPase activity of KRAS

Recently reported to be effective in patients with lung cancer, KRASG12C inhibitors bind to the inactive, or guanosine diphosphate (GDP)–bound, state of the oncoprotein and require guanosine triphosphate (GTP) hydrolysis for inhibition. However, KRAS mutations prevent the catalytic arginine of GTPase-activating proteins (GAPs) from enhancing an otherwise slow hydrolysis rate. If KRAS mutants are indeed insensitive to GAPs, it is unclear how KRASG12C hydrolyzes sufficient GTP to allow inactive state–selective inhibition. Here, we show that RGS3, a GAP previously known for regulating G protein–coupled receptors, can also enhance the GTPase activity of mutant and wild-type KRAS proteins. Our study reveals an unexpected mechanism that inactivates KRAS and explains the vulnerability to emerging clinically effective therapeutics.

Circadian regulation of vertebrate cone photoreceptor function

Eukaryotes generally display a circadian rhythm as an adaption to the reoccurring day/night cycle. This is particularly true for visual physiology that is directly affected by changing light conditions. Here we investigate the influence of the circadian rhythm on the expression and function of visual transduction cascade regulators in diurnal zebrafish and nocturnal mice. We focused on regulators of shut-off kinetics such as Recoverins, Arrestins, Opsin kinases, and Regulator of G-protein signaling that have direct effects on temporal vision. Transcript as well as protein levels of most analyzed genes show a robust circadian rhythm-dependent regulation, which correlates with changes in photoresponse kinetics. Electroretinography demonstrates that photoresponse recovery in zebrafish is delayed in the evening and accelerated in the morning. Functional rhythmicity persists in continuous darkness, and it is reversed by an inverted light cycle and disrupted by constant light. This is in line with our finding that orthologous gene transcripts from diurnal zebrafish and nocturnal mice are often expressed in an anti-phasic daily rhythm.

MicroRNA-3935 promotes human trophoblast cell epithelial-mesenchymal transition through tumor necrosis factor receptor-associated factor 6/regulator of G protein signaling 2 axis

BACKGROUND

Insufficient migration and invasion during trophoblast epithelial-mesenchymal transition (EMT) results in the occurrence and development of preeclampsia (PE), and our previous study has screened 52 miRNAs, whose expression levels are altered in the placental samples from PE patients, compared with the normal group. Among those, miR-3935 is one of the miRNAs being most significantly down-regulated, indicating its involvement in PE. However, the exact effect and molecular mechanisms remain unknown.

METHODS

In the present study, we investigate the roles and underlying mechanisms of miR-3935 in trophoblast EMT by use of the human extra-villous trophoblast cell line HTR-8/SVneo as well as human placental tissues and maternal blood samples obtained from 15 women with normal pregnancies and 15 women with PE. Experimental methods include transfection, quantitative reverse transcription-PCR (qRT-PCR), western blot, immunofluorescence staining, dual-luciferase assays, in vitro invasion and migration assays, RNA-Seq analysis, bisulfite sequencing and immunohistochemistry staining.

RESULTS

MiR-3935 expression is significantly decreased in both placentas and peripheral blood specimens of PE, and functionally, miR-3935 promotes EMT of trophoblast cells. Mechanistically, TRAF6 is identified to be a direct target of miR-3935 and TRAF6 exerts its negative effect on EMT of trophoblast cells by inhibition of RGS2, which down-regulates the methylation status of promoter of CDH1 gene that encodes E-Cadherin protein through induction of ALKBH1, resulting in increase of E-Cadherin and subsequently insufficient trophoblast EMT.

CONCLUSIONS

Together these results uncover a hitherto uncharacterized role of miR-3935/TRAF6/RGS2 axis in the function of human trophoblasts, which may pinpoint the molecular pathogenesis of PE and may be a prognostic biomarker and therapeutic target for such obstetrical diseases as PE.

LINC00370 modulates miR-222-3p-RGS4 axis to protect against osteoporosis progression

BACKGROUND

We aimed to determine the role of the LINC00370/miR-222-3p/RGS4 axis in modulating the process of adipose-derived stem cell (ADSC) osteogenic differentiation.

METHODS

We first evaluated the differential expression of LINC00370, miR-222-3p and RGS4 between normal and osteogenically induced ADSCs. Moreover, we transfected ADSCs with LINC00370 siRNA and an miR-222-3p inhibitor to determine the role of LINC00370 in modulating the process of ADSC osteogenic differentiation. Finally, we analyzed the dual-luciferase reporter gene to identify the relationship between LINC00370 and miR-222-3p. We first created osteoporotic rat models by ovariectomy (OVX) and treated with pcDNA-LINC00370. HE and immunohistochemical staining of OCN were performed to assess the changes in bone microarchitecture.

RESULTS

LINC00370 and RGS4 expression was remarkably upregulated in the osteogenic ADSC group compared with the normal medium group. On the other hand, miR-222-3p expression was remarkably decreased in the osteogenic group compared with the normal medium group. Knockdown of LINC00370 reduced the osteogenic differentiation of ADSCs. Moreover, the inhibitor of miR-222-3p partially reversed the reduction of osteogenic differentiation by LINC00370 knockdown. Knockdown of LINC00370 reduced the expression of p-Akt and p-PI3K. The inhibitor of miR-222-3p partially reversed the reduction of the expression of p-Akt and p-PI3K by LINC00370 knockdown. A dual luciferase reporter assay indicated that LINC00370 can directly bind miR-222-3p. LINC00370 suppressed OP progression in OVX and partially upregulated OCN protein expression.

CONCLUSION

Collectively, the above results confirm that LINC00370 promotes the process of ADSC osteogenic differentiation via the miR-222-3p/RGS4 axis. Moreover, LINC00370 could protect against OVX-induced OP.

RGS5 Determines Neutrophil Migration in the Acute Inflammatory Phase of Bleomycin-Induced Lung Injury

The regulator of G protein signaling (RGS) represents a widespread system of controllers of cellular responses. The activities of the R4 subfamily of RGSs have been elucidated in allergic pulmonary diseases. However, the R4 signaling in other inflammatory lung diseases, with a strong cellular immune response, remained unexplored. Thus, our study aimed to discern the functional relevance of the R4 family member, RGS5, as a potential modulating element in this context. Gene profiling of the R4 subfamily showed increased RGS5 expression in human fibrosing lung disease samples. In line with this, RGS5 was markedly increased in murine lungs following bleomycin injury. RGS knock-out mice (RGS-/-) had preserved lung function while control mice showed significant combined ventilatory disorders three days after bleomycin application as compared to untreated control mice. Loss of RGS5 was associated with a significantly reduced neutrophil influx and tissue myeloperoxidase expression. In the LPS lung injury model, RGS5-/- mice also failed to recruit neutrophils into the lung, which was accompanied by reduced tissue myeloperoxidase levels after 24 h. Our in-vitro assays showed impaired migration of RGS5-/- neutrophils towards chemokines despite preserved Ca²⁺ signaling. ERK dephosphorylation might play a role in reduced neutrophil migration in our model. As a conclusion, loss of RGS5 preserves lung function and attenuates hyperinflammation in the acute phase of bleomycin-induced pulmonary fibrosis and LPS-induced lung injury. Targeting RGS5 might alleviate the severity of exacerbations in interstitial lung diseases.