Interleukin Enhancer Binding Factor 2 Regulates Cell Viability and Apoptosis of Human Brain Vascular Smooth Muscle Cells

NF90-NF45 is essential for β cell compensation under obesity-inducing metabolic stress through suppression of p53 signaling pathway

The Nuclear Factor 90 (NF90)-NF45 complex has been known to regulate the progression of transcription, mRNA stability, translational inhibition, RNA export and microRNA biogenesis. However, the physiological functions of the NF90-NF45 complex remain unclear. We newly discovered that the NF90-NF45 complex was expressed in primary β cells and established cell lines. Therefore, in this study, we focused on the function of the endogenous NF90-NF45 complex in the β cells. To investigate this issue, we generated β-cell-specific NF90-NF45 deficient mice. These mice exhibited hyperglycaemia and lower plasma insulin levels under a high fat diet together with decreased islet mass. To uncover this mechanism, we performed a whole-genome expression microarray of the total RNA prepared from β cell lines treated with siRNAs targeting both NF90 and NF45. In this result, we found an activation of p53 signaling in the NF90-NF45-knockdown cells. This activation was supported by elevation of luciferase activity derived from a reporter plasmid harboring p53 binding sites in the NF90-NF45-knockdown cells. Furthermore, the knockdown of NF90-NF45 resulted in a significant retardation of the β cell line growth rates. Importantly, a dominant negative form of p53 rescues the growth retardation in BTC6 cells depleted of NF90-NF45, suggesting that NF90-NF45 would be positively involved in β cell proliferation through suppression of p53 signal pathway. Taken together, NF90-NF45 is essential for β cell compensation under obesity-inducing metabolic stress via repression of p53 signaling.

CircRNA DOCK1 Regulates miR-409-3p/MCL1 Axis to Modulate Proliferation and Apoptosis of Human Brain Vascular Smooth Muscle Cells

Background

Intracranial aneurysm is an abnormal expansion in the intracranial arteries, which is associated with growth and apoptosis of vascular smooth muscle cells. Circular RNAs (circRNAs) have implicated in the progression of intracranial aneurysms. The purpose of this paper is to study the function and mechanism of circRNA dedicator of cytokinesis 1 (circ_DOCK1) in regulating proliferation and apoptosis of human brain vascular smooth muscle cells (HBVSMCs).

Methods

HBVSMCs were exposed to hydrogen peroxide (H₂O₂). Cell proliferation and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and flow cytometry, respectively. Circ_DOCK1, microRNA (miR)-409-3p, and myeloid cell leukemia sequence 1 (MCL1) levels were examined by quantitative reverse transcription polymerase chain reaction or western blotting. The target association was assessed by dual-luciferase reporter, RNA pull-down, and RNA immunoprecipitation assays.

Results

Exposure to H₂O₂ decreased proliferation and increased apoptosis of HBVSMCs. Circ_DOCK1 expression was reduced in H₂O₂-treated HBVSMCs. Circ_DOCK1 overexpression rescued H₂O₂-caused reduction of proliferation and PCNA expression and attenuated H₂O₂-induced apoptosis and expression of Bcl-2, Bax, and cleaved PARP. MiR-409-3p was targeted by circ_DOCK1 and upregulated in H₂O₂-treated HBVSMCs. MiR-409-3p upregulation mitigated the role of circ_DOCK1 in proliferation and apoptosis of H₂O₂-treated HBVSMCs. MCL1 was targeted via miR-409-3p and downregulated via H₂O₂ treatment. Circ_DOCK1 overexpression enhanced MCL1 expression via modulating miR-409-3p. MiR-409-3p knockdown weakened H₂O₂-induced proliferation reduction and apoptosis promotion via regulating MCL1.

Conclusion

Circ_DOCK1 overexpression mitigated H₂O₂-caused proliferation inhibition and apoptosis promotion in HBVSMCs by modulating miR-409-3p/MCL1 axis.