17β-Estradiol,through activating the G protein-coupled estrogen receptor,exacerbates the complication of benign prostatic hyperplasia in type 2 diabetes mellitus patients by inducing prostate proliferation

Benign prostatic hyperplasia(BPH)is one of the major chronic complications of type 2 diabetes mellitus(T2DM),and sex steroid hormones are common risk factors for the occurrence of T2DM and BPH.The profiles of sex steroid hormones are simultaneously quantified by LC-MS/MS in the clinical serum of patients,including simple BPH patients,newly diagnosed T2DM patients,T2DM complicated with BPH patients and matched healthy individuals.The G protein-coupled estrogen receptor(GPER)inhibitor G15,GPER knockdown lentivirus,the YAP1 inhibitor verteporfin,YAP1 knockdown/overexpression lentivirus,targeted metabolomics analysis,and Co-IP assays are used to investigate the molecular mechanisms of the disrupted sex steroid hormones homeostasis in the pathological process of T2DM complicated with BPH.The homeostasis of sex steroid hormone is disrupted in the serum of patients,accompanying with the proliferated prostatic epithelial cells(PECs).The sex steroid hormone metabolic profiles of T2DM patients complicated with BPH have the greatest degrees of separation from those of healthy individuals.Elevated 17β-estradiol(E2)is the key contributor to the disrupted sex steroid hormone homeostasis,and is significantly positively related to the clinical characteristics of T2DM patients complicated with BPH.Activating GPER by E2 via Hippo-YAP1 signaling exacerbates high glucose(HG)-induced PECs proliferation through the formation of the YAP1-TEAD4 heterodimer.Knockdown or inhibition of GPER-mediated Hippo-YAP1 signaling suppresses PECs proliferation in HG and E2 co-treated BPH-1 cells.The anti-proliferative effects of verteporfin,an inhibitor of YAP1,are blocked by YAP1 overexpression in HG and E2 co-treated BPH-1 cells.Inactivating E2/GPER/Hippo/YAP1 signaling may be effective at delaying the progression of T2DM complicated with BPH by inhibiting PECs proliferation.

Roles of G protein-coupled receptors in inflammatory bowel disease

Inflammatory bowel disease(IBD)is a complex disease with multiple pathogenic factors.Although the pathogenesis of IBD is still unclear,a current hypothesis suggests that genetic susceptibility,environmental factors,a dysfunctional immune system,the microbiome,and the interactions of these factors substantially contribute to the occurrence and development of IBD.Although existing and emerging drugs have been proven to be effective in treating IBD,none can cure IBD permanently.G protein-coupled receptors(GPCRs)are critical signaling molecules implicated in the immune response,cell proliferation,inflammation regulation and intestinal barrier maintenance.Breakthroughs in the understanding of the structures and functions of GPCRs have provided a driving force for exploring the roles of GPCRs in the pathogenesis of diseases,thereby leading to the development of GPCR-targeted medication.To date,a number of GPCRs have been shown to be associated with IBD,significantly advancing the drug discovery process for IBD.The associations between GPCRs and disease activity,disease severity,and disease phenotypes have also paved new avenues for the precise management of patients with IBD.In this review,we mainly focus on the roles of the most studied proton-sensing GPCRs,cannabinoid receptors,and estrogen-related GPCRs in the pathogenesis of IBD and their potential clinical values in IBD and some other diseases.

Arrestin-mediated signaling: Is there a controversy?

The activation of the mitogen-activated protein(MAP) kinases extracellular signal-regulated kinase(ERK)1/2 was traditionally used as a readout of signaling of G protein-coupled receptors(GPCRs) via arrestins, as opposed to conventional GPCR signaling via G proteins. Several recent studies using HEK293 cells where all G proteins were genetically ablated or inactivated, or both non-visual arrestins were knocked out, demonstrated that ERK1/2 phosphorylation requires G protein activity, but does not necessarily require the presence of non-visual arrestins. This appears to contradict the prevailing paradigm. Here we discuss these results along with the recent data on gene edited cells and arrestinmediated signaling. We suggest that there is no real controversy. G proteins might be involved in the activation of the upstream-most MAP3Ks, although in vivo most MAP3K activation is independent of heterotrimeric G proteins, being initiated by receptor tyrosine kinases and/or integrins. As far as MAP kinases are concerned, the best-established role of arrestins is scaffolding of the three-tiered cascades(MAP3K-MAP2 K-MAPK). Thus, it seems likely that arrestins, GPCRbound and free, facilitate the propagation of signals in these cascades, whereas signal initiation via MAP3K activation may be independent of arrestins. Different MAP3Ks are activated by various inputs, some of which are mediated by G proteins, particularly in cell culture, where we artificially prevent signaling by receptor tyrosine kinases and integrins, thereby favoring GPCR-induced signaling. Thus, there is no reason to change the paradigm: Arrestins and G proteins play distinct non-overlapping roles in cell signaling.

GRK5 is an essential co-repressor of the cardiac mineralocorticoid receptor and is selectively induced by finerenone

BACKGROUND In the heart,aldosterone(Aldo)binds the mineralocorticoid receptor(MR)to exert damaging,adverse remodeling-promoting effects.We recently showed that G protein-coupled receptor-kinase(GRK)-5 blocks the cardiac MR by directly phosphorylating it,thereby repressing its transcriptional activity.MR antagonist(MRA)drugs block the cardiac MR reducing morbidity and mortality of advanced human heart failure.Non-steroidal MRAs,such as finerenone,may provide better cardio-protection against Aldo than classic,steroidal MRAs,like spironolactone and eplerenone.AIM To investigate potential differences between finerenone and eplerenone at engaging GRK5-dependent cardiac MR phosphorylation and subsequent blockade.METHODS We used H9c2 cardiomyocytes,which endogenously express the MR and GRK5.RESULTS GRK5 phosphorylates the MR in H9c2 cardiomyocytes in response to finerenone but not to eplerenone.Unlike eplerenone,finerenone alone potently and efficiently suppresses cardiac MR transcriptional activity,thus displaying inverse agonism.GRK5 is necessary for finerenone’s inverse agonism,since GRK5 genetic deletion renders finerenone incapable of blocking cardiac MR transcriptional activity.Eplerenone alone does not fully suppress cardiac MR basal activity regardless of GRK5 expression levels.Finally,GRK5 is necessary for the antiapoptotic,anti-oxidative,and anti-fibrotic effects of both finerenone and eplerenone against Aldo,as well as for the higher efficacy and potency of finerenone at blocking Aldo-induced apoptosis,oxidative stress,and fibrosis.CONCLUSION Finerenone,but not eplerenone,induces GRK5-dependent cardiac MR inhibition,which underlies,at least in part,its higher potency and efficacy,compared to eplerenone,as an MRA in the heart.GRK5 acts as a co-repressor of the cardiac MR and is essential for efficient MR antagonism in the myocardium.

Ligand dose-dependent activation of signaling pathways through the gustatory receptor NlGr11 linked to feeding efficacy in Nilaparvata lugens

Insects often face both conditions with sufficient nutrients and conditions of undernutrition in the field.Through gustatory receptors,insects sense nutrients and regulate their physiological functions such as feeding and reproduction.However,it remains unclear whether signaling pathways activated by gustatory receptors depend on the concentration of nutrients and whether the difference in signaling pathways directly affects insects’physiological functions.Herein,we found that a sugar gustatory receptor,NlGr11,from the brown planthopper(BPH),Nilaparvata lugens,activated G protein-coupled signaling and ionotropic pathways when bound to high galactose concentration.BPHs subsequently demonstrated longer feeding times,feeding loads,and higher vitellogenin(NlVg)expression than BPHs exposed to high galactose concentrations,which only activated the ionotropic pathway.For the first time,our findings link plant nutrient conditions,signaling pathways activated by nutrients,and their gustatory receptors,and nutrient dose-dependent feeding efficacy and vitellogenin(Vg)expression in an insect.This will help us to better understand the molecular mechanism for insect feeding strategies on plants at different stages of nutritional conditions.

Modulating effects of RAMPs on signaling profiles of the glucagon receptor family

Receptor activity-modulating proteins(RAMPs)are accessory molecules that form complexes with specific G protein-coupled receptors(GPCRs)and modulate their functions.It is established that RAMP interacts with the glucagon receptor family of GPCRs but the underlying mechanism is poorly understood.In this study,we used a bioluminescence resonance energy transfer(BRET)approach to comprehensively investigate such interactions.In conjunction with c AMP accumulation,Gaqactivation andβ-arrestin1/2 recruitment assays,we not only verified the GPCR-RAMP pairs previously reported,but also identified new patterns of GPCR-RAMP interaction.While RAMP1 was able to modify the three signaling events elicited by both glucagon receptor(GCGR)and glucagon-like peptide-1 receptor(GLP-1 R),and RAMP2 mainly affectedβ-arrestin1/2 recruitment by GCGR,GLP-1 R and glucagon-like peptide-2 receptor,RAMP3 showed a widespread negative impact on all the family members except for growth hormone-releasing hormone receptor covering the three pathways.Our results suggest that RAMP modulates both G protein dependent and independent signal transduction among the glucagon receptor family members in a receptor-specific manner.Mapping such interactions provides new insights into the role of RAMP in ligand recognition and receptor activation.

Regulatory effects of GRK2 on GPCRs and possible use as a drug target

G protein-coupled receptor kinase 2(GRK2),as a key Ser/Thr protein kinase,belong to the member of the G protein-coupled receptor kinase(GRK)family.The C-terminus of GRK2 including a plekstrin homology domain and the N-terminus of GRK2 including the RGS homology domain with binding sites for several proteins and lipids such as G protein-coupled receptors(GPCRs),G protein,phospholipase C,phosphatidylinositol 4,5-bisphosphate,extracellular signal-regulated kinase,protein kinase A and Gβγ,which can regulate the activity of GRK2.GRK2 can regulate GPCR desensitization and internalization by phosphorylating the GPCR,promoting the affinity of binding to arrestins,and uncoupling the receptors from G proteins,which play an important role in maintaining the balance between the receptors and signal transduction.Previous studies have indicated that cardiac GRK2overexpression can promote the phosphorylation ofβ-adrenergic receptor(βAR)leading toβAR desensitization and internalization,which play a pivotal role in inducing heart failure(HF)-related dysfunction and myocyte death.GRK2,as a regulator of cell function,is overexpression in hypertension.Overexpression GRK2 can inhibit Akt/e NOS signaling pathway and decreased the production and activation of e NOS leading to endothelial dysfunction.Collagen-induced arthritis induces the upregulation of GRK2 expression in fibroblast-like synoviocytes.In this review,we mainly discussed the evidence for the association between GRK2 overexpression and various diseases,which suggests that GRK2 may be an effective drug target for preventing and treating heart failure,hypertension and inflammatory disease.

Not all arrestins are created equal: Therapeutic implications of the functional diversity of the β-arrestins in the heart

The two ubiquitous, outside the retina, G protein-coupled receptor(GPCR)adapter proteins, β-arrestin-1 and-2(also known as arrestin-2 and-3,respectively), have three major functions in cells: GPCR desensitization, i.e.,receptor decoupling from G-proteins; GPCR internalization via clathrin-coated pits; and signal transduction independently of or in parallel to G-proteins. Bothβ-arrestins are expressed in the heart and regulate a large number of cardiac GPCRs. The latter constitute the single most commonly targeted receptor class by Food and Drug Administration-approved cardiovascular drugs, with about onethird of all currently used in the clinic medications affecting GPCR function.Since β-arrestin-1 and-2 play important roles in signaling and function of several GPCRs, in particular of adrenergic receptors and angiotensin II type 1 receptors,in cardiac myocytes, they have been a major focus of cardiac biology research in recent years. Perhaps the most significant realization coming out of their studies is that these two GPCR adapter proteins, initially thought of as functionally interchangeable, actually exert diametrically opposite effects in the mammalian myocardium. Specifically, the most abundant of the two β-arrestin-1 exerts overall detrimental effects on the heart, such as negative inotropy and promotion of adverse remodeling post-myocardial infarction(MI). In contrast, β-arrestin-2 is overall beneficial for the myocardium, as it has anti-apoptotic and antiinflammatory effects that result in attenuation of post-MI adverse remodeling,while promoting cardiac contractile function. Thus, design of novel cardiac GPCRligands that preferentially activate β-arrestin-2 over β-arrestin-1 has the potential of generating novel cardiovascular therapeutics for heart failure and other heart diseases.