LncRNA HOTTIP Knockdown Attenuates Acute Myocardial Infarction via Regulating miR-92a-2/c-Met Axis

Exercise in ozone-polluted air evokes pathological cardiac hypertrophy via up-regulation of nuclear lncRNA EYA4-au1 and recruiting Med11 to activating EYA4/p27kip1/CK2α/HDAC2 cascade

Engaging in exercise in an ozone (O3)-polluted environment can lead to lung damage, respiratory inflammation, and deterioration in performance, however, the effects on the heart are undefined. Herein, we report that rats performing moderate-intensity exercise under O3-polluted air evoked pathological myocardial hypertrophy (MH). O3 exposure increased serum levels of MH-promoting factors (angiotensin II [AngII], endothelin-1 [ET-1], and cyclophilin A [CyPA]), and decreased expression of MH-inhibiting factors (adiponectin [ADPN], follistatin-like protein 1 [FSTL1], and apelin). O3 exposure also increased the expression levels of cardiac hypertrophy markers (ANP, BNP, and β-MHC) in the heart, elicited myocardial hypertrophy and cardiac inflammation. Mechanistically, we identified lncRNA EYA4-au1 overexpression in the above myocardial tissues with pathological hypertrophy. In an AngII-elicited in vitro model, EYA4-au1 was shown to mediate cardiomyocyte hypertrophy. AngII induces nuclear translocation of SP1, leading to high expression of EYA4-au1; And inhibits the expression of ELAVL1, resulting in nuclear retention of EYA4-au1. Nuclear EYA4-au1 recruits Med11 to EYA4 promoter for transcriptional activation, subsequently unleashing the EYA4/p27kip1/CK2α/HDAC2 cascade that signals cardiomyocyte hypertrophy. In summary, O3 exposure is an important factor in pathological MH, mediated by EYA4-au1 that motivates the MH-driving EYA4 pathway. Our findings define the effects of exercise on the heart in an O3-polluted environment and offer a novel mechanistic route for the onset of MH.

LncRNA CCRR maintains Ca2+ homeostasis against myocardial infarction through the FTO-SERCA2a pathway

Cardiac conduction regulatory RNA (CCRR) has been documented as an antiarrhythmic lncRNA in our earlier investigation. This study aimed to evaluate the effects of CCRR on SERCA2a and the associated Ca2+ homeostasis in myocardial infarction (MI). Overexpression of CCRR via AAV9-mediated delivery not only partially reversed ischemia-induced contractile dysfunction but also alleviated abnormal Ca2+ homeostasis and reduced the heightened methylation level of SERCA2a following MI. These effects were also observed in CCRR over-expressing transgenic mice. A conserved sequence domain of CCRR mimicked the protective function observed with the full length. Furthermore, silencing CCRR in healthy mice led to intracellular Ca2+ overloading of cardiomyocytes. CCRR increased SERCA2a protein stability by upregulating FTO expression. The direct interaction between CCRR and FTO protein was characterized by RNA-binding protein immunoprecipitation (RIP) analysis and RNA pulldown experiments. Activation of NFATc3 was identified as an upstream mechanism responsible for CCRR downregulation in MI. This study demonstrates that CCRR is a protective lncRNA that acts by maintaining the function of FTO, thereby reducing the m6A RNA methylation level of SERCA2a, ultimately preserving calcium homeostasis for myocardial contractile function in MI. Therefore, CCRR may be considered a promising therapeutic strategy with a beneficial role in cardiac pathology.

Long non-coding RNA HOTTIP promotes renal cell carcinoma progression through the regulation of the miR-506 pathway

HOXA transcript at the distal tip (HOTTIP), a lncRNA, induces cell proliferation and cancer progression. However, the expression and function of HOTTIP in renal cell carcinoma (RCC) were rarely reported. The role of the HOTTIP in RCC was explored in this study. HOTTIP expresses higher in RCC tissues than in normal tissues and indicates poor prognosis based on the TCGA database. The over- and low-expression HOTTIP cell line was established in this research to assess the oncogenic function of HOTTIP in RCC progression. Mechanistic analyses revealed that HOTTIP functioned as a competing endogenous RNA (ceRNA) for miR-506. RIP experiment and luciferase assay were performed to explore the mechanisms of the sponge between HOTTIP and miR-506. HOTTIP down-regulation attenuated cell proliferation, migration, and invasion, which could be rescued by miR-506 down-regulation. On the whole, this study revealed that the HOTTIP/miR-506 axis has a dominant impact on RCC progression and potentially provides a novel strategy for RCC diagnosis and therapy.

Protectin D1 Alleviates Myocardial Ischemia/Reperfusion Injury by Regulating PI3K/AKT Signaling Pathway

Myocardial ischemia/reperfusion (I/R) injury after the onset of acute myocardial infarction (AMI) can be life-threatening, and there is no effective strategy for therapeutic intervention. Here, we studied the potential of protectin D1 in protecting from I/R-induced cardiac damages and investigated the underlying mechanisms. An in vivo rat model of I/R after AMI induction was established through the ligation of the left anterior descending (LAD) artery to assess the cardiac functions and evaluate the protective effect of protectin D1. Protectin D1 protected against I/R-induced oxidative stress and inflammation in the rat model, improved the cardiac function, and reduced the infarct size in myocardial tissues. The beneficial effect of protectin D1 was associated with the up-regulation of miRNA-210 and the effects on PI3K/AKT signaling and HIF-1α expression. Together, our data suggest that protectin D1 could serve as a potential cardioprotective agent against I/R-associated cardiac defects.

Spotlight on HOX cluster‑embedded antisense lncRNAs in cardiovascular diseases (Review)

Atherosclerosis is a complex and chronic inflammatory disease driven by multiple pathophysiological processes that are responsible for diverse cardiovascular events. Atherosclerotic cardiovascular disease, despite substantial triumphs in primary and secondary prevention, remains a dominant epidemic that impairs human health. Therefore, deciphering the pathogenesis of atherosclerosis will provide a real‑world translational understanding. Homeobox cluster‑embedded antisense long non‑coding RNAs (HOX‑lncRNAs), a nascent class of lncRNA molecules with versatile roles in cancer, can also orchestrate various cell functions in cardiovascular disorders and have thus captured the attention of many researchers. Subsequently, numerous studies have demonstrated the role of HOX‑lncRNAs as potential modulators of atherosclerosis. Nevertheless, given that the understanding of HOX‑lncRNAs in atherosclerosis is only just emerging, ongoing research must be initiated to thoroughly pinpoint such causal roles. The present review aimed to highlight the important contributions of HOX‑lncRNAs to atherosclerosis and other pivotal biological processes related to cardiovascular disease. The review concludes with a discussion of the limitations, outlook, challenges and possible solutions associated with HOX‑lncRNAs in atherosclerosis. Looking forward, this may lead to extraordinary breakthroughs in revealing the molecular underpinnings of HOX‑lncRNAs and may offer a promising yet challenging landscape for robust therapeutic strategies for atherosclerosis and/or associated cardiovascular disorders.

LncRNA HOTTIP promotes inflammatory response in acute gouty arthritis via miR-101-3p/BRD4 axis

INTRODUCTION

Acute gouty arthritis (AGA) is characterized by the accumulation of pro-inflammatory factors. This research aimed to examine the regulation of long non-coding RNA HOXA distal transcript antisense RNA (HOTTIP) in AGA on inflammation and its potential mechanisms.

METHODS

Serum levels of HOTTIP in AGA patients were examined by reverse-transcription quantitative polymerase chain reaction. The receiver operating characteristic curve was performed in the diagnosis of AGA patients. Monosodium urate (MSU) stimulation of THP-1-derived macrophages was used to establish an in vitro AGA model. Enzyme-linked immunosorbent assay was carried out to assess the levels of pro-inflammatory cytokines. Pearson correlation was applied to examine the correlation. RNA immunoprecipitation assay and dual-luciferase reporter assay were employed to identify the targeting relationship between miR-101-3p and HOTTIP or bromodomain-containing 4 (BRD4).

RESULTS

HOTTIP and BRD4 were statistically overexpressed in AGA patients compared with controls, while miR-101-3p was reduced (P < 0.05). Serum HOTTIP can significantly distinguish AGA patients from healthy controls. HOTTIP bound with miR-101-3p then augmented BRD4 via a competing endogenous RNA mechanism. Additionally, HOTTIP levels were elevated in a dose-dependent manner by MSU (P < 0.05). Weakened HOTTIP significantly inhibited MSU-induced release of pro-inflammatory factors interleukin (IL)-1β, IL-8, and transforming growth factor-α in macrophages (P < 0.05), but this inhibition was reversed by silencing miR-101-3p (P < 0.05).

CONCLUSION

In short, HOTTIP contributes to inflammation via miR-101-3p/BRD4 axis, and serves as a new diagnostic biomarker. This study offers a renewed perspective on the diagnosis and treatment of AGA.

Knockdown of long noncoding RNA MIAT attenuates hypoxia-induced cardiomyocyte injury by regulating the miR-488-3p/Wnt/β-catenin pathway

Dysfunction of cardiomyocytes contributes to the development of acute myocardial infarction (AMI). Nonetheless, the regulatory mechanism of lncRNA myocardial infarction-associated transcript (MIAT) in cardiomyocyte injury remains largely unclear. The cardiomyocyte injury was assessed via cell viability and apoptosis using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) and flow cytometry, respectively. The levels of MIAT, microRNA (miR)-488-3p, and Wnt5a were detected via quantitative real-time polymerase chain reaction and Western blot. After bioinformatical analysis, the binding between miR-488-3p and MIAT or Wnt5a was confirmed via dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays. Our results showed that MIAT expression was increased in AC16 cells after hypoxia treatment. Silencing of MIAT alleviated hypoxia-induced viability reduction, apoptosis increase, and Wnt/β-catenin pathway activation. MIAT directly targeted miR-488-3p. MiR-488-3p might repress hypoxia-induced cardiomyocyte injury, and its knockdown reversed the effect of MIAT depletion on cardiomyocyte injury. Wnt5a was validated as a target of miR-488-3p. Wnt5a expression restoration attenuated the influence of MIAT knockdown on hypoxia-triggered cardiomyocyte injury. Our findings demonstrated that downregulation of MIAT might mitigate hypoxia-induced cardiomyocyte injury partly through miR-488-3p mediated Wnt/β-catenin pathway.