LncRNA-Mhrt regulates cardiac hypertrophy by modulating the miR-145a-5p/KLF4/myocardin axis
Introduction
The human genome contains approximately 20,000 protein-coding genes, which account for only approximately 2% of the whole genome. The remaining 98% can be transcribed into RNAs of different lengths without coding ability or weak coding ability (ncRNAs) [1,2]. A large number of ncRNAs are involved in the regulation of gene expression. ncRNAs greater than 200 nt in length are called lncRNA, and lncRNAs can interact with transcription factors and affect their activity. In addition, lncRNAs can affect the function of miRNA by acting as a sponge that absorbs miRNAs. Therefore, lncRNA has an important function in regulating the development of the body and the occurrence of diseases.
Cardiac hypertrophy is an early milestone of many heart diseases that occurs in response to a variety of intrinsic or extrinsic stimuli [3,4]. The occurrence of cardiac hypertrophy is related to the interaction of transcription factors, lncRNAs and many other factors. With the development of high-throughput sequencing technology, some heart development-related lncRNAs have been identified. However, unlike cardiac transcription factors, which are extensively studied, the function of cardiac lncRNAs remains largely unrevealed, especially in cardiac hypertrophy [5].
Mhrt (myosin heavy chain associated RNA transcript) is an lncRNA encoded by the gene of myosin heavy chain 7, which protects the heart from pathological hypertrophy [6]. As shown in our previous study, Mhrt modulates the acetylation of myocardin by altering the nuclear location of HDAC5, thereby regulating the occurrence of cardiac hypertrophy. We also found that Mhrt inhibited the expression of myocardin mRNA and protein [7]. As an SRF co-transcription factor, myocardin is critical for heart development and the occurrence of cardiac hypertrophy [8,9]. We assessed how Mhrt regulates the expression of myocardin. Are transcriptional regulatory factors in myocardin-related signaling pathways targets of Mhrt?
KLF4, a member of the KLF family, regulates the proliferation and differentiation of endothelial and smooth muscle cells [[10], [11], [12], [13], [14]]. Notably, KLF4 inhibits the occurrence of cardiac hypertrophy by downregulating the expression of myocardin through direct binding with the promoter region of myocardin [15]. Coincidentally, we used bioinformatics to predict that miR-145a-5p links Mhrt and KLF4, which potentially degrades KLF4 mRNA. Furthermore, KLF4 ubiquitination may occur, resulting in protein hydrolysis after KLF4 phosphorylation. In addition, lncRNA may also regulate the modification of certain proteins. Does Mhrt regulate KLF4 expression and protein modification? These are the topics we want to discuss in this article.
The aim of this study is to reveal the possible molecular mechanism of the regulation of myocardin expression by Mhrt in the occurrence and development of cardiac hypertrophy to provide a theoretical basis for the development of new drug targets in clinical practice.
Section snippets
Cardiomyocytes isolation and culture
Primary neonatal mouse cardiomyocytes were isolated from 2- to 3-day-old C57BL/6 mice hearts under sterile conditions using mild enzymatic (0.1% collagenasetype II and 0.08% trypsin) digestion and gentle mechanical trituration as described previously [16]. After centrifugation, cells were resuspended in DMEM/F-12 (GIBCO) containing 10% fetal bovine serum (FBS, Gibco.), 100 U/mL penicillin, 100 μg/mL streptomycin, and 0.1 mM bromodeoxyuridine and placed in different dishes for culture.
Cell culture
The Cos-7
Mhrt increases KLF4 expression
To explore the potential effect of Mhrt on KLF4 expression, we first investigated whether the KLF4 expression level was altered under Mhrt overexpression or silencing conditions in primary cardiomyocytes (Fig. 1A-1B). KLF4 mRNA and protein levels were significantly increased with Mhrt overexpression compared with the control group (Fig. 1C, E). Moreover, primary cardiomyocytes lacking Mhrt expression showed significantly decreased KLF4 mRNA and protein levels (Fig. 1D, F). These findings
Discussion
Increasing evidence has demonstrated that a large number of lncRNAs have important effects on the development of cardiovascular disease. LncRNA Bvht is potentially involved in the process of cardiomyocyte differentiation [27], and abnormal lncRNA SRA1 transcription is closely related to dilated cardiomyopathy [28]. In zebrafish, knockout of the lncRNA SRA1 significantly reduced ventricular contractile function [29]. The silencing of AK143260 leads to the loss of the pulsation ability of
Disclosures
None.
Acknowledgements
This work was supported by the National Natural Science Foundation of China (No. 31570764).
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Circulatory long noncoding RNAs (circulatory-LNC-RNAs) as novel biomarkers and therapeutic targets in cardiovascular diseases: Implications for cardiovascular diseases complications
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2022, Molecular Therapy Nucleic AcidsCitation Excerpt :Of further therapeutic interest, Mhrt, alongside another myocardium-specific lncRNA cardiac hypertrophy-associated transcript (CHAST), has earlier been measured hypermethylated in a murine infarcted myocardium and to demethylate after local myocardial FTO silencing yielding a beneficial phenotype.107 Indeed, Mhrt is a cardiac-specific lncRNA transcribed from the antisense strand of Myh7 gene with a protective role against hypertrophy by sequestering the brahma-related gene-1 (Brg1) mRNA to consequently blunt the prohypertrophic transition from myosin heavy chain 6 (MYH6) to myosin heavy chain 7 (MYH7) expression dominance.337,338 Interestingly, triiodothyronine upregulates Mhrt in I/R-injury339 and has been linked to predict MI340 and HF.341
SUMOylation of SIRT1 activating PGC-1α/PPARα pathway mediates the protective effect of LncRNA-MHRT in cardiac hypertrophy
2022, European Journal of PharmacologyCitation Excerpt :A previous study found that MHRT inhibited myocardial hypertrophy by Brg1 (Han et al., 2014). It has also been shown that MHRT inhibits acetylation and expression of myocardin, which plays a key role in cardiac hypertrophy (Xu et al., 2020; Luo et al., 2018). However, whether MHRT inhibits cardiac hypertrophy by activating PGC-1α/PPARα pathway through SUMOylation of SIRT1 is unclear.
Overexpression of cytosolic long noncoding RNA cytb protects against pressure-overload-induced heart failure via sponging microRNA-103-3p
2022, Molecular Therapy Nucleic AcidsCitation Excerpt :lncRNA ZFAS1 exists in both the nucleus and cytosol, causing intracellular Ca2+ overload and contractile dysfunction by acting as a SERCA2a inhibitor.42 However, lncRNA Mhrt located in the cytosol could modulate cardiac hypertrophy via the miR-145a-5p/KLF4/myocardin axis.43 Recently, several studies have demonstrated that molecules derived from mitochondria play crucial roles in the pathophysiological process when exported to the cytosol.
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These authors contributed equally to this work.