ABSTRACT
G protein-coupled receptors (GPCRs) represent the largest family of membrane proteins and are the target of approximately half of all therapeutic drugs. There are ～300 orphan GPCRs, which have great potential in drug development. G protein-coupled receptor 35 (GPR35), a rhodopsin-like orphan GPCR, is widely involved in immune regulation, gastrointestinal disorders, cardiovascular diseases, cancer, as well as other diseases, suggesting its great potential as a therapeutic target in a variety of diseases. However, the current research on GPR35 is insufficient, including the true endogenous ligand has not been confirmed, the molecular mechanism of its role in disease is not fully understood, and there is a lack of effective intervention strategies targeting GPR35. This article summarizes the deorphatization of GPR35, GPR35-related signaling pathways and their association with various diseases, in order to provide a reference for in-depth study of GPR35 in diseases and development of drugs targeting GPR35.
ABSTRACT
Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. Fat accumulation "sensitizes" the liver to insult and leads to nonalcoholic steatohepatitis (NASH). G protein-coupled receptor 35 (GPR35) is involved in metabolic stresses, but its role in NAFLD is unknown. We report that hepatocyte GPR35 mitigates NASH by regulating hepatic cholesterol homeostasis. Specifically, we found that GPR35 overexpression in hepatocytes protected against high-fat/cholesterol/fructose (HFCF) diet-induced steatohepatitis, whereas loss of GPR35 had the opposite effect. Administration of the GPR35 agonist kynurenic acid (Kyna) suppressed HFCF diet-induced steatohepatitis in mice. Kyna/GPR35 induced expression of StAR-related lipid transfer protein 4 (STARD4) through the ERK1/2 signaling pathway, ultimately resulting in hepatic cholesterol esterification and bile acid synthesis (BAS). The overexpression of STARD4 increased the expression of the BAS rate-limiting enzymes cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and CYP8B1, promoting the conversion of cholesterol to bile acid. The protective effect induced by GPR35 overexpression in hepatocytes disappeared in hepatocyte STARD4-knockdown mice. STARD4 overexpression in hepatocytes reversed the aggravation of HFCF diet-induced steatohepatitis caused by the loss of GPR35 expression in hepatocytes in mice. Our findings indicate that the GPR35-STARD4 axis is a promising therapeutic target for NAFLD.
ABSTRACT
OBJECTIVE：To provide reference for elucidating the anti-allergic asthma constituents in alkaloids-free part of Ephedrae Herba. METHODS ：Ephedrae Herba was extracted with 85％ ethanol and n-heptane，and then subjected to solid-phase extraction（filler AC 18）for pretreatment to enrich alkaloids-free part from the extract of Ephedrae Herba. HPLC method was adopted，and alkaloids-free fractions of Ephedrae Herba were performed on Unitary C 18 column and Eclipse XDB-C 18 column. Using high expression G protein coupled-receptor 35（GPR35 receptor）in HT- 29 cell as target ，GPR35 receptor agonist zaprinast （1 μmol/L）as positive control ，DMR response value as the detection index ，the agonistic and desensitizing activity of each fraction（100 μg/mL）on GPR 35 receptor was screened by label-free integrated pharmacological method ，so as to screen active anti-allergic asthma fraction. HPLC-Q-TOF-MS method was used to identify the chemical composition of the selected active fractions. RESULTS ：The alkaloids-free part of Ephedrae Herba was divided into two parts ，involving the precipitated part before solid phase extraction and the 95％ methanol elution part ；from them ，20 fractions were screened. Among them ，the precipitated fraction F 1.5-F1.10 and 95％ methanol eluted fraction F 2.5-F2.10 had a strong agonistic activity on GPR 35 receptor；at the same time，GPR35 receptor agonist zaprinast showed a relatively strong desensitization activity. The signal intensity of DMR induced by F1.5-F1.10 in the precipitated part of HT- 29 cells was even higher than that of reference drug zaprinast. By HPLC-Q-TOF-MS analysis，24 chemical components were identified from active fractions ，involving 14 flavonoids，2 volatile oils ，7 organic carboxylic acids ，1 anthraquinones. CONCLUSIONS ：The alkaloid-free part of Ephedrae Herba is mainly flavonoids and has anti-allergic asthma activity.
ABSTRACT
Objective To investigate the function of G-protein-coupled receptor 35 (GPR35) in aortic dissection (AD) and its mechanism. Methods Thirty wild-type (WT) male mice were randomly divided into the WT+Sham group and WT+AD group (15 each), and 15 GPR35 knockout mice (GPR35-/-) were set as GPR35-/-+AD group. Mice in WT+AD group and GPR35-/-+AD group were back-subcutaneously implanted with angiotensin II [4.5 mg/(kg·24 h)] by miniosmotic pump, while in WT+Sham group received equivalent saline. Mice were sacrificed and the aortas were removed on the 14th postoperative day for further experiments. The mice aortic vascular smooth muscle cell lines (MOVAS) were divided into control group, aortic dissection group (AD group), GPR35 inhibitor group (CID group). The expressions of GPR35 in aorta and MOVAS were determined by q-PCR and Western blotting. The aortas were stained with HE and VVG to detect the formation of aortic dissection and elastic fiber structure. The infiltration of monocyte macrophage (CD68 positive cell) and expression of inflammatory factors (IL)-6 and (TNF)-α in aorta were detected with immunohistochemistry and q-PCR. The apoptosis of aortic smooth muscle was measured by TUNEL staining and flow cytometer. Results Compared with the WT+Sham group, the expression of GPR35 mRNA increased by (1.88±0.07) times and of GPR35 protein increased by (1.34±0.05) times in WT+AD group (P<0.05), and similar results were obtained in cell model; Compared with the WT+AD group, the incidence of AD decreased obviously in GPR35-/-+AD group (53.3% vs. 13.3%, P<0.05), meanwhile the aortic dilatation, media thickness and elastic fiber structure were attenuated evidently; Furthermore, the mononuclear macrophage infiltration (CD68 positive cells) were elevated in WT+AD group than in WT+Sham group and GPR35-/-+ AD group [(32.8±1.1)% vs. (5.1±0.9)% vs. (16.0±1.1)%] with statistical significance (P<0.05). The expression levels of IL-6 and TNF-α mRNA were higher in WT+AD group (2.6±0.1, 1.8±0.1) than in WT+Sham group (both 1.00±0.06) and GPR35-/-+ AD group (1.6±0.1, 1.4±0.1) with statistical significance (P<0.05); The number of apoptotic aortic smooth muscle cells in WT+AD group [(24.0±0.7)%] was more than that in WT+Sham group and GPR35-/-+AD group [(6.6±0.5)% and (11.2±0.9)%] with statistical significance (P<0.05). Meanwhile, the apoptosis rate of MOVAS was also significantly higher in AD group [(11.6±0.5)%] than in control group and CID group [(4.7±0.4)% and (7.6±0.4)%, P<0.05]. Conclusion Inhibition of GPR35 can protect aortic dissection by preventing aortic inflammation and smooth muscle apoptosis.