INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
·
2023
·Vol. 24
·期 12
·10031
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IF 5.6
Haiping Liu,Haixiang Ma,Xingyue Zeng,Chengyan Wu,Srijan Acharya,Sarabjeet Kour Sudan,Xiaohan Zhang
A class-A GPCR dopamine D2 receptor (D2R) plays a critical role in the proper functioning of neuronal circuits through the downstream activation of both G-protein- and β-arrestin-dependent signaling pathways. Understanding the signaling pathways downstream of D2R is critical for developing effective therapies with which to treat dopamine (DA)-related disorders such as Parkinson’s disease and schizophrenia. Extensive studies have focused on the regulation of D2R-mediated extracellular-signal-regulated kinase (ERK) 1/2 signaling; however, the manner in which ERKs are activated upon the stimulation of a specific signaling pathway of D2R remains unclear. The present study conducted a variety of experimental techniques, including loss-of-function experiments, site-directed mutagenesis, and the determination of protein interactions, in order to investigate the mechanisms underlying β-arrestin-biased signaling-pathway-mediated ERK activation. We found that the stimulation of the D2R β-arrestin signaling pathway caused Mdm2, an E3 ubiquitin ligase, to move from the nucleus to the cytoplasm and interact with tyrosine phosphorylated G-protein-coupled receptor kinase 2 (GRK2), which was facilitated by Src, a non-receptor tyrosine kinase. This interaction led to the ubiquitination of GRK2, which then moved to the plasma membrane and interacted with activated D2R, followed by the phosphorylation of D2R as well as the mediation of ERK activation. In conclusion, Mdm2-mediated GRK2 ubiquitination, which is selectively triggered by the stimulation of the D2R β-arrestin signaling pathway, is necessary for GRK2 membrane translocation and its interaction with D2R, which in turn mediates downstream ERK signaling. This study is primarily novel and provides essential information with which to better understand the detailed mechanisms of D2R-dependent signaling.Keywords:GRK2 ubiquitination;D2R-biased signaling;Src;ERK signaling
研究领域:
神经科学
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药理学
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细胞信号
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产品关联
DOI
PubMed
高影响因子
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY
·
2025
·
IF 4.7
Qianying Shen,Yue-Yue Zhou,Yan-Lin Wang,Yao Qi,Dong-Bo Lian,Zhe-Hong Li,Meng-Fei Chen,Xiao-Li Zhang,Yue Zhang,Jin Song,Li-Fei Zheng,Jin-Xia Zhu
Long-term infection with Helicobacter pylori (H. pylori) leads to elevated serum gastrin levels, which are closely related to gastric cancer. Eradication of H. pylori to treat the high gastrin levels is increasingly challenged by antibiotic resistance. Dopamine (DA) receptor 1 (D1R) is expressed on G cells in the gastric antrum. Parietal cells produce DA, which inhibits somatostatin (SOM) release through D2R on D cells in the gastric mucosa. Whether targeted intervention in DRs can improve high gastrin levels after H. pylori infection remains to be explored. In this study, human gastric tissue, H. pylori-infected mice, D1R and D2R knockout mice, RT‒qPCR, ELISA, IHC, Western Blot, HE staining and ex vivo incubation of gastric mucosae were used. We found that H. pylori infection destroyed the mitochondria of parietal cells and reduced DA content in the gastric mucosa at 10 weeks after infection. Moreover, gastrin-positive cell numbers and serum gastrin levels were increased. D1R, but not D2R, was observed in G cells. DA promoted gastric gastrin secretion. Interestingly, both D1- and D2-like agonists mimicked the effect of DA on the gastrin secretion, which was antagonized by their antagonists. Blocking D2R with domperidone or knocking out D2R resulted in decreased gastrin-positive cell numbers and gastrin levels but increased SOM levels at 10 weeks after H. pylori infection. Our findings highlight the key regulatory effect of D2R on gastrin secretion and elucidate the role of domperidone in reducing the elevated gastrin level associated with H. pylori infection.
研究领域:
医学
·
分子生物学
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消化病学
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DOI
PubMed
高影响因子
Cell Communication and Signaling
·
2024
·Vol. 22
·期 1
·1-21
·
IF 8.2
Wu Chengyan,Hu Li,Liu Bing,Zeng Xingyue,Ma Haixiang,Cao Yongkai,Li Huijun,Zhang Xiaohan
Background Desensitization of G protein–coupled receptors (GPCRs) refers to the attenuation of receptor responsiveness by prolonged or intermittent exposure to agonists. The binding of β-arrestin to the cytoplasmic cavity of the phosphorylated receptor, which competes with the G protein, has been widely accepted as an extensive model for explaining GPCRs desensitization. However, studies on various GPCRs, including dopamine D 2 -like receptors (D 2 R, D 3 R, D 4 R), have suggested the existence of other desensitization mechanisms. The present study employed D 2 R/D 3 R variants with different desensitization properties and utilized loss-of-function approaches to uncover the mechanisms underlying GPCRs homologous desensitization, focusing on the signaling cascade that regulates the ubiquitination of AKT. Results AKT undergoes K8/14 ubiquitination by TRAF6, which occurs in the nucleus and promotes its membrane recruitment, phosphorylation and activation under receptor desensitization conditions. The nuclear entry of TRAF6 relies on the presence of the importin complex. Src regulates the nuclear entry of TRAF6 by mediating the interaction between TRAF6 and importin β1. Ubiquitinated AKT translocates to the plasma membrane where it associates with Mdm2 to phosphorylate it at the S166 and S186 residues. Thereafter, phosphorylated Mdm2 is recruited to the nucleus, resulting in the deubiquitination of β-Arr2. The deubiquitinated β-Arr2 then forms a complex with Gβγ, which serves as a biomarker for GPCRs desensitization. Like in D 3 R, ubiquitination of AKT is also involved in the desensitization of β 2 adrenoceptors. Conclusion Our study proposed that the property of a receptor that causes a change in the subcellular localization of TRAF6 from the cytoplasm to the nucleus to mediate AKT ubiquitination could initiate the desensitization of GPCRs.
研究领域:
细胞生物学
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分子生物学
·
药理学
·
信号转导
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产品关联
DOI
PubMed
高影响因子
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