LGR4 and LGR5 are R-spondin receptors mediating Wnt/β-catenin and Wnt/PCP signalling

R-spondins are secreted Wnt signalling agonists, which regulate embryonic patterning and stem cell proliferation, but whose mechanism of action is poorly understood. Here we show that R-spondins bind to the orphan G-protein-coupled receptors LGR4 and LGR5 by their Furin domains. Gain- and loss-of-function experiments in mammalian cells and Xenopus embryos indicate that LGR4 and LGR5 promote R-spondin-mediated Wnt/β-catenin and Wnt/PCP signalling. R-spondin-triggered β-catenin signalling requires Clathrin, while Wnt3a-mediated β-catenin signalling requires Caveolin-mediated endocytosis, suggesting that internalization has a mechanistic role in R-spondin signalling.     

LGR4通过调控上皮-间充质转化促进宫颈癌转移

LGR4(leucine-rich repeat-containing G-protein-coupled receptor 4)在多种肿瘤发生中具有重要作用,但在宫颈癌(cervical cancer)中的作用及机制尚不清楚.该研究使用免疫组织化学技术检测宫颈癌组织中LGR4的表达情况,发现LGR4在癌组织中的蛋白水...     

LGR5 interacts and cointernalizes with Wnt receptors to modulate Wnt/β-catenin signaling

LGR5, a seven-transmembrane domain receptor of the rhodopsin family, is a Wnt target gene and a bona fide marker of adult stem cells in the gastrointestinal tract and hair follicle bulge. Recently, we and others demonstrated that LGR5 and its homologues function as receptors of the R-spondin family of stem cell factors to potentiate Wnt/β-catenin signaling. However, the mechanism of how LGR5 enhances the signaling output remains unclear. Here we report that following costimulation with the ligands R-spondin1 and Wnt3a, LGR5 interacts and forms a supercomplex with the Wnt coreceptors LRP6 and Fzd5 which is rapidly internalized and then degraded. Internalization of LGR5 is mediated through a dynamin- and clathrin-dependent pathway. Inhibition of this endocytic process has no effect on LGR5 signaling. Deletion of the C-terminal tail of LGR5 maintains its ability to interact with LRP6, yet this LGR5 mutant exhibits increased signaling activity and a decreased rate of endocytosis in response to R-spondin1 compared to the wild-type receptor. This study provides direct evidence that LGR5 becomes part of the Wnt signaling complex at the membrane level to enhance Wnt/β-catenin signaling. However, internalization of LGR5 does not appear to be essential for potentiating the canonical Wnt signaling pathway.     

血清PG、LGR4与胃癌患者腹腔镜D2根治术预后相关性分析

摘要 目的：探讨与分析血清胃蛋白酶原（PG）、多富含亮氨酸重复单位的G蛋白偶联受体4（LGR4）与胃癌患者腹腔镜D2根治术（LD2RS）预后相关性。方法：2021年1月到2021年12月选择在本院进行诊治的胃癌患者210例作为胃癌组,同期选择在本院进行体检的健康者210例作为对照组。检测两组人群的血清血清PG、LGR4含量,调查患者预后并进行相关性分析。结果：胃癌组的血清PGⅠ含量低于对照组,血清LGR4、PG Ⅱ含量高于对照组（P<0.05）。平均手术时间154.98±19.43 min;平均术中出血量148.62±15.83 mL;平均术后肠功能恢复时间2.51±0.29 d;平均术后肛门排气时间2.79±0.16 d;平均术后下床活动时间2.33±0.15 d;平均术后住院时间9.28±0.29 d。术后14 d发生并发症24例,占比11.4 %。胃癌组所有患者随访至今,平均随访时间为17.38±2.15个月,预后发生转移23例,占比11.0 %;复发14例,占比6.7 %。Spearsman分析显示胃癌患者预后转移、复发与血清PGⅠ、PGⅡ、LGR4含量存在相关性（P<0.05）。多因素logistic回归显示血清PGⅠ、PGⅡ、LGR4为导致患者预后复发、转移的重要因素（P<0.05）。结论：腹腔镜D2根治术治疗胃癌具有很好的安全性与微创性,但是预后复发率与转移率依然比较高,血清PG、LGR4与胃癌患者腹腔镜D2根治术预后存在相关性,也是导致预后复发与转移的重要因素。     

Rspo1、LGR5、NF-κB/p65在胃癌中的表达及其临床意义

目的 通过检测特异性顶部盘状底板反应蛋白1(Rspo1)、富含亮氨酸的重复G蛋白偶联受体5(LGR5)与核转录因子κB/p65(NF-κB/p65)在人胃癌中的表达水平及与临床病理因素及预后之间的关系,并分析三者在胃癌发生发展中发挥的作用。方法 免疫组织化学SP法测定Rspo1、LGR5及NF-κB/p65在115例胃癌组织标本及20例正常组织标本中的表达。结果 Rspo1、LGR5、NF-κB/p65在胃癌中表达较正常组织增高;Rspo1、LGR5、NF-κB/p65的表达与浸润深度、TNM分期、淋巴结及远处转移有关,同时Rspo1表达与肿瘤大小、LGR5表达与肿瘤大小及分化程度有关;胃癌组织中Rspo1与LGR5、NF-κB/p65的表达呈正相关;Kaplan-Meier分析显示Rspo1、LGR5和NF-κB/p65表达阳性组3年生存率均低于阴性组;单因素Cox分析提示肿瘤大小、分化程度、浸润深度、淋巴结转移、远处转移、Rspo1、LGR5、NF-κB/p65阳性是影响胃癌患者预后的危险因素;多因素Cox分析提示淋巴结转移、远处转移、Rspo1及LGR5阳性是影响胃癌患者预后的独立危险因素。结论 Rspo1、LGR5、NF-κB/p65的表达与胃癌的发生发展有关;Rspo1-LGR5在激活Wnt/β-catenin通路的同时可能激活NF-κB通路,二者对胃癌发展有协同作用。     

Ascending aortic adventitial remodeling and fibrosis are ameliorated with Apelin-13 in rats after TAC via suppression of the miRNA-122 and LGR4-β-catenin signaling

Apelin has been proved to be a critical mediator of vascular function and homeostasis. Here, we investigated roles of Apelin in aortic remodeling and fibrosis in rats with transverse aortic constriction (TAC). Male Sprague-Dawley rats were subjected to TAC and then randomized to daily deliver Apelin-13 (50 μg/kg) or angiotensin type 1 receptor (AT1) blocker Irbesartan (50 mg/kg) for 4 weeks. Pressure overload resulted in myocardial hypertrophy, systolic dysfunction, aortic remodeling and adventitial fibrosis with reduced levels of Apelin in ascending aortas of rat after TAC compared with sham-operated group. These changes were associated with marked increases in levels of miRNA-122, TGFβ1, CTGF, NFAT5, LGR4, and β-catenin. More importantly, Apelin and Irbesartan treatment strikingly prevented TAC-mediated aortic remodeling and adventitial fibrosis in pressure overloaded rats by blocking AT1 receptor and miRNA-122 levels and repressing activation of the CTGF-NFAT5 and LGR4-β-catenin signaling. In cultured primary rat adventitial fibroblasts, exposure to angiotensin II (100 nmol L⁻¹) led to significant increases in cellular migration and levels of TGFβ1, CTGF, NFAT5, LGR4 and β-catenin, which were effectively reversed by pre-treatment with Apelin (100 nmol L⁻¹) and miRNA-122 inhibitor (50 nmol L⁻¹). In conclusion, Apelin counterregulated against TAC-mediated ascending aortic remodeling and angiotensin II-induced promotion of cellular migration by blocking AT1 receptor and miRNA-122 levels and preventing activation of the TGFβ1-CTGF-NFAT5 and LGR4-β-catenin signaling, ultimately contributing to attenuation of aortic adventitial fibrosis. Our data point to Apelin as an important regulator of aortic remodeling and adventitial fibrosis and a promising target for vasoprotective therapies.