ABSTRACT
Objective: To study the impact of interferon-inducible protein 16 (IFI16) inhibition on apoptosis of human aortic adventitial fibroblasts (HAAFs). Methods: Our research included 3 groups: ① IFI16-siRNA group, specific small interference RNAs (siRNAs) of IFI16 were transfected into HAAFs in vitro to make IFI16 gene silence, ②Con-siRNA group, non-specific siRNAs were transfected into HAAFs as negative control and ③Untreated HAAFs group, blank control. HAAFs cell cycle and apoptosis rate were examined by flow cytometry, IFI16 mRNA expression was measured by real time qRT-PCR, protein expressions of IFI16, p53, p21, Bax and Bcl-2 were detected by Western blot analysis. Results: Compared with Con-siRNA group and Untreated HAAFs group, IFI16-siRNA group showed decreased apoptosis rate of HAAFs (3.33±0.41) % vs (7.42±1.51) % and (6.49±1.10) %, P<0.05, reduced ratio of G0/G1 phase cells (56.64 ± 4.77 ) % vs (69.67±3.54) % and (68.29±4.14) %, P<0.05, while increased ratio of S phase cells (25.23±5.19)% vs (13.76±2.07) % and (14.04±3.00) %, P<0.05. Meanwhile, IFI16-siRNA group presented down-regulated IFI16 mRNA and protein expressions, decreased protein levels of p53, p21, Bax and increased protein level of Bcl-2, all P<0.05. Conclusion: Inhibited IFI16 expression could decrease HAAFs apoptosis, promote cell cycle transition from G1 to S phase which might be related to the suppression of p53/p21 signaling pathway and regulation of Bax/Bcl-2 expression.
ABSTRACT
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).