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Objective To construct the promoter enhanced green fluorescent protein (pEGFP1) reporter gene vector of different truncated fragments of human cellular repressor of E1A-stimulated genes (hCREG), and compare the transcriptional activity of each promoter to determine the hCREG core promoter region. Methods The promoter fragment with length of 2003 (–1925/+78) bp was obtained by querying the hCREG sequence from US National Center of Biotechnology Information (NCBI) database and combining with the characteristics of the promoter. Five promoter fragments were truncated by PCR and double enzyme digestion and cloned into pEGFP1 to construct pEGFP1_hCREG_2003, pEGFP1_hCREG_945, pEGF P1_hCREG_586, pEGFP1_ hCREG_478 and pEG FP1_hCREG_358 reporter gene vector plasmid. The 293T cells were transiently co-transfected with the internal reference plasmid pGL4.73 [hRluc/SV40] for 48 hours. The green fluorescence expression of pEGFP1_hCREG promoter reporter gene was observed under fluorescence microscope, and the mRNA expression of each promoter was detected by real-time quantitative PCR, and the core promoter region was determined. Bioinformatics was used to predict the transcription factors that might bind to the core promoter region. Results Five hCREG promoter reporter gene vectors were successfully constructed by double enzyme digestion and gene sequencing. The results showed that the transcription activity of pEGFP1_ hCREG_586 was the highest (P0.05), implying that –867/ –509 bp is a negative regulatory region, and there existed enhancer sequences in –400/–281 bp and –508/–401 bp, so the core promoter region of hCREG gene is located in the upstream sequence of –508/–281 bp. Bioinformatics predicted that the possibly bound transcription factors in key promoter region –508/–281 bp were Pax5/P53, C/EBPβ, GR-β, GATA-1, GR-α, c-Jun, PRB/ PRA, YY1, RXR-α, AP-2, FOXP3, GR, TFIID, STAT4 and c-Ets-1. Conclusion The recombinant plasmid of hCREG gene promoter has been successfully constructed, the core promoter of which is located in –508/–281 bp, where several transcription factors might be bound.
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Objective To investigate the effect of cellular repressor of E1A stimulated genes (CREG1) on cardiac function in mouse with myocardial fibrosis. Methods CREG1 knockout mice (CREG1+/-) and CREG1 wild-type mice (CREG1+/+) were used to reproduce the model of myocardial fibrosis by subcutaneous pump burying of angiotensin Ⅱ (AngⅡ). After being stimulated with AngⅡ for 14 days, myocardial fibrosis was verified by HE staining and Masson trichrome staining. Western blotting and immunohistochemistry were used to detect the expression of CREG1 in myocardium before stimulation and 3, 7, 14 days after the AngⅡ stimulation. The cardiac function was evaluated by echocardiography after AngⅡ stimulation for 14 days. The CREG+/+ mice were given AngⅡ for 14 days, and at the same time recombinant CREG1 protein [respectively 15, 30, 60 and 300μg/(kg.d), intraperitoneal (IP) injections] (treatment group) and NaCl (control group) were administered for treatment, and then cardiac function and myocardiac apoptosis were examined. Results Western blotting and immunohistochemistry showed that the expression of CREG1 in heart tissue was significantly lower in CREG+/-mice than in CREG+/+ mice (P<0.05). After AngⅡ stimulation for 3, 7 and 14 days, the expression of CREG1 in heart tissue declined significantly in both CREG+/-and CREG+/+ mice (P<0.05), especially in CREG+/-mice (P<0.01). With HE and Masson staining, it was also found that CREG1 deficiency aggravated myocardial fibrosis and cardiac function deterioration in response to AngⅡ stimulation (P<0.05). Conversely, exogenous infusion of recombinant CREG1 protein significantly inhibited the occurrence of myocardial apoptosis (P<0.05), thus ameliorated cardiac function (P<0.05). Conclusions CREG1 deficiency may aggravate the deterioration of cardiac function in mouse with myocardial fibrosis induced by AngⅡ stimulation. The deterioration of cardiac function can be improved by administration of exogenous recombinant CREG1 protein.
RESUMO
Objective To explore possible role of cellular repressor of E1A-stimulated genes(CREG) in the process of phenotypic switching of adventitial fibroblasts(AFs). Methods Immunofluorescent staining was performed with tissue sections from mouse carotid arteries to evaluate the relationship between the expression of CREG and smooth muscle actin-α(α-SMA) in injured arteries, especially in the adventitia. Tissue block pasted culture method was used to isolate and culture AFs. RT-PCR and Western-blot were used to detect the change of CREG andα-SMA mRNA and protein expression in AFs in the presence of different concentrations of AngⅡfor 12 h/24 h or in the presence of 100 nmol/L Ang Ⅱ for different times. Results Normal mouse carotid arteries had little α-SMA expression throughout the tunica adventitia. Arteries at day 1 and day 3 post-injury exhibited significantly higher immunofluorescence of α-SMA compared with non-injured arteries. Alpha-SMA expression began to decrease on day 7 and progressively declined on day 14. In contrast, immunofluorescent staining revealed that CREG was expressed in the adventitia of normal arteries. Expression of CREG in the adventitia of injured arteries was decreased on the 1st day, reached its lowest value on the 3rd day, and increased gradually from the 7th day, and was higher compared with that in non-injured arteries on the 14th day after injury. Similarly, the expression of CREG in AFs was very high, and AngⅡremarkably decreased mRNA and protein expression levels of CREG in a dose-dependent and time-dependent manner. Conclusions The changes in CREG expression correlate with AF phenotypic modulation, and CREG down-regulation may facilitate AF phenotypic switching into myofibroblasts (MFs).