ALKBH5 Exacerbates Aortic Dissection by Promoting Inflammatory Response and Apoptosis of Aortic Smooth Muscle Cells via Regulating lnc-TMPO-AS1/EZH2/IRAK4 Signals in an m6A Modification Manner

Peng Wang,Min Zhang,Zhiwei Wang,Shun Yuan,Qi Wu,Feng Shi,Ciccarelli Michele

doi:10.1155/2021/5513966

Abstract

Recently, mounting evidence indicates that N6-methyladenosine (m6A) modification functions as a pivotal posttranscriptional modification that regulates noncoding RNA biogenesis to influence the progression of multiple diseases. However, whether m6A modification is involved in aortic dissection (AD) development has never been reported. Meanwhile, numerous studies have shown that AngII-induced inflammatory damage and excessive apoptosis of human aortic smooth muscle cells (HASMCs) are the crucial pathological features of AD development. Therefore, in this study, we intended to explore whether m6A modification can regulate AD progression by influencing the damage effects of AngII on HASMCs and elucidate the underlying mechanisms. Firstly, we screened and confirmed the high expression of alkylation repair homolog protein 5 (ALKBH5), a key m6A demethylase, in aortic tissues from AD patients, indicating that m6A modification may indeed be involved in AD progression. Subsequently, we demonstrated that ALKBH5 can exacerbate the AngII-induced HASMC inflammatory injury as well as apoptosis and shorten the survival time of AngII-infused mice. Mechanistically, we revealed that lncRNA TMPO-AS1 is a downstream target for ALKBH5 to affect AD progression in vitro and vivo. Meanwhile, we confirmed that ALKBH5-mediated m6A demethylation downregulates lnc-TMPO-AS1 by decreasing the stability of its nascent. Further, we demonstrated that lnc-TMPO-AS1 exhibits its functions in HASMCs, at least partly, through downregulating IRAK4 at the epigenetic level by combining with EZH2. Finally, the direct positive correlation between ALKBH5 and IRAK4 in terms of the expression level and biological function was confirmed, which further enforced the preciseness and correctness of our findings. In conclusion, our study demonstrated that ALKBH5 aggravates AD by promoting inflammatory response and apoptosis of HASMCs via regulating lnc-TMPO-AS1/EZH2/IRAK4 signals in an m6A modification manner and may provide a novel molecular basis for subsequent researchers to searching for novel therapeutic approaches to improve the health of patients fighting AD and other cardiovascular diseases.

Highlights

Aortic dissection (AD) is a life-threatening cardiovascular emergency due to a tear in the aorta intima or bleeding within the aortic wall, leading to the separation of the different layers of the aortic wall [1, 2]
The results of western blot revealed the low expression of KIAA1429 and the high expression of ALKBH5 in aortic tissues from AD patients compared with donors (Figure 1(b); Supplementary Fig. 1)
The aberrant expression of ALKBH5 in AD tissues derived from humans and mice and human aortic smooth muscle cells (HASMCs) treated with angiotensin II (AngII) was verified, suggesting that m6A modification might be involved in the development of AD

Summary

Introduction

Aortic dissection (AD) is a life-threatening cardiovascular emergency due to a tear in the aorta intima or bleeding within the aortic wall, leading to the separation of the different layers of the aortic wall [1, 2]. Our previous study has demonstrated that treating ASMCs with a certain concentration of angiotensin II (AngII) can simulate the status of cellular injury during the development of AD in the physiological state [6]. In the present study, we intended to identify some signaling molecules that could regulate AD progression by influencing the damage effects of AngII on HASMCs and clarify their mechanisms of action. M6A modification is demonstrated by many studies to be a dynamic and reversible process, constructed primarily by a methyltransferase complex called m6A “writers,” including methyltransferase like 3 (METTL3), vir-like methyltransferase (VIRMA), coupled with WT1-associated protein (WTAP) and removed by demethylases called m6A “erasers,” including alkylation repair homolog protein 5 (ALKBH5) and fat mass and obesity-associated protein (FTO) [13, 14]

Methods

Results

Conclusion