MALAT1: a therapeutic candidate for a broad spectrum of vascular and cardiorenal complications

Long Noncoding RNA MALAT1: Salt-Sensitive Hypertension

Hypertension stands as the leading global cause of mortality, affecting one billion individuals and serving as a crucial risk indicator for cardiovascular morbidity and mortality. Elevated salt intake triggers inflammation and hypertension by activating antigen-presenting cells (APCs). We found that one of the primary reasons behind this pro-inflammatory response is the epithelial sodium channel (ENaC), responsible for transporting sodium ions into APCs and the activation of NADPH oxidase, leading to increased oxidative stress. Oxidative stress increases lipid peroxidation and the formation of pro-inflammatory isolevuglandins (IsoLG). Long noncoding RNAs (lncRNAs) play a crucial role in regulating gene expression, and MALAT1, broadly expressed across cell types, including blood vessels and inflammatory cells, is also associated with inflammation regulation. In hypertension, the decreased transcriptional activity of nuclear factor erythroid 2-related factor 2 (Nrf2 or Nfe2l2) correlates with heightened oxidative stress in APCs and impaired control of various antioxidant genes. Kelch-like ECH-associated protein 1 (Keap1), an intracellular inhibitor of Nrf2, exhibits elevated levels of hypertension. Sodium, through an increase in Sp1 transcription factor binding at its promoter, upregulates MALAT1 expression. Silencing MALAT1 inhibits sodium-induced Keap1 upregulation, facilitating the nuclear translocation of Nrf2 and subsequent antioxidant gene transcription. Thus, MALAT1, acting via the Keap1-Nrf2 pathway, modulates antioxidant defense in hypertension. This review explores the potential role of the lncRNA MALAT1 in controlling the Keap1-Nrf2-antioxidant defense pathway in salt-induced hypertension. The inhibition of MALAT1 holds therapeutic potential for the progression of salt-induced hypertension and cardiovascular disease (CVD).

Non-Coding RNAs and Prediction of Preeclampsia in the First Trimester of Pregnancy

Preeclampsia (PE) is a major cause of maternal and perinatal morbidity and mortality. The only fundamental treatment for PE is the termination of pregnancy. Therefore, not only severe maternal complications but also perinatal complications due to immaturity of the infant associated with early delivery are serious issues. The treatment and prevention of preterm onset preeclampsia (POPE) are challenging. In 2017, the ASPRE trial showed that a low oral dose of aspirin administered to POPE high-risk women in early pregnancy reduced POPE by 62%. A prediction algorithm at 11–13 weeks of gestation identifies POPE with 75% sensitivity when the false positive rate is set at 10%. New biomarkers to increase the accuracy of the prediction model for POPE high-risk women in early pregnancy are needed. In this review, we focused on non-coding RNAs (ncRNAs) as potential biomarkers for the prediction of POPE. Highly expressed ncRNAs in the placenta in early pregnancy may play crucial roles in placentation. Furthermore, placenta-specific ncRNAs have been detected in maternal blood. In this review, we summarized ncRNAs that were highly expressed in the primary human placenta in early pregnancy. We also presented highly expressed ncRNAs in the placenta that were associated with or predictive of the development of PE in an expression analysis of maternal blood during the first trimester of pregnancy. These previous studies showed that the chromosome 19 microRNA (miRNA) -derived miRNAs (e.g., miR-517-5p, miR-518b, and miR-520h), the hypoxia-inducible miRNA (miR-210), and long non-coding RNA H19, were not only highly expressed in the early placenta but were also significantly up-regulated in the blood at early gestation in pregnant women who later developed PE. These maternal circulating ncRNAs in early pregnancy are expected to be possible biomarkers for POPE.

MALAT1 regulates hypertrophy of cardiomyocytes by modulating the miR-181a/HMGB2 pathway

Noncoding RNAs are important for the regulation of cardiac hypertrophy. The function of MALAT1 (a long noncoding mRNA), miR-181a, and HMGB2, their contribution to cardiac hypertrophy, and the regulatory relationship between them during this process remain unknown. In the present study, we treated primary cardiomyocytes with angiotensin II (Ang II) to mimic cardiac hypertrophy. MALAT1 expression was significantly downregulated in Ang II-treated cardiomyocytes compared with control cardiomyocytes. Ang II-induced cardiac hypertrophy was suppressed by overexpression of MALAT1 and promoted by genetic knockdown of MALAT1. A dual-luciferase reporter assay demonstrated that MALAT1 acted as a sponge for miR-181a and inhibited its expression during cardiac hypertrophy. Cardiac hypertrophy was suppressed by overexpression of an miR-181a inhibitor and enhanced by overexpression of an miR-181a mimic. HMGB2 was downregulated during cardiac hypertrophy and was identified as a target of miR-181a by bioinformatics analysis and a dual-luciferase reporter assay. miR-181a overexpression decreased the mRNA and protein levels of HMGB2. Rescue experiments indicated that MALAT1 overexpression reversed the effect of miR-181a on HMGB2 expression. In summary, the results of the present study show that MALAT1 acts as a sponge for miR-181a and thereby regulates expression of HMGB2 and development of cardiac hypertrophy. The novel MALAT1/miR-181a/HMGB2 axis might play a crucial role in cardiac hypertrophy and serve as a new therapeutic target.

Downregulation of lncRNA MALAT1 Inhibits Angiotensin II-induced Hypertrophic Effects of Cardiomyocytes by Regulating SIRT4 via miR-93-5p

Cardiac hypertrophy is a leading risk for heart failure and sudden death. Long non-coding RNAs (lncRNAs) have been implicated in a variety of human diseases, including cardiac hypertrophy. We aimed to investigate the potential role and functional mechanism of lncRNA metastasis-associated in lung adenocarcinoma transcript 1 (MALAT1) in cardiac hypertrophy. C57BL/6 mice underwent transverse aortic constriction (TAC) to induce cardiac hypertrophy in vivo. The expression of MALAT1, miR-93-5p, and sirtuin 4 (SIRT4) mRNA was detected using a quantitative real-time polymerase chain reaction. The protein levels of cardiac hypertrophy-related markers, including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP) and β-myosin heavy chain (β-MHC), and SIRT4 were measured via western blotting. The putative interaction between miR-93-5p and MALAT1 or SIRT4 was verified using a dual-luciferase reporter assay, RNA immunoprecipitation assay, or pull-down assay. Consequently, the expression of MALAT1 and SIRT4 was increased in TAC-treated mouse heart and angiotensin II (Ang-II)-induced cardiomyocytes, whereas the expression of miR-93-5p was decreased. Ang-II promoted the expression of ANP, BNP, and β-MHC and the surface area of cardiomyocytes, whereas MALAT1 downregulation impaired their expression and cell area. MiR-93-5p was a target of MALAT1, and its inhibition reversed the effects of MALAT1 downregulation. More importantly, MALAT1 modulated SIRT4 expression by degrading miR-93-5p. The expression of ANP, BNP, and β-MHC suppressed by miR-93-5p restoration was recovered by SIRT4 promotion. Overall, MALAT1 knockdown ameliorated cardiac hypertrophy partly by regulating the miR-93-5p/SIRT4 network, indicating that MALAT1 was a substantial indicator of cardiac hypertrophy.

An update on the functional roles of long non‑coding RNAs in ischemic injury (Review)

Ischemic injuries result from ischemia and hypoxia in cells. Tissues and organs receive an insufficient supply of nutrients and accumulate metabolic waste, which leads to the development of inflammation, fibrosis and a series of other issues. Ischemic injuries in the brain, heart, kidneys, lungs and other organs can cause severe adverse effects. Acute renal ischemia induces acute renal failure, heart ischemia induces myocardial infarction and cerebral ischemia induces cerebrovascular accidents, leading to loss of movement, consciousness and possibly, life-threatening disabilities. Existing evidence suggests that long non-coding RNAs (lncRNAs) are regulatory sequences involved in transcription, post-transcription, epigenetic regulation and multiple physiological processes. lncRNAs have been shown to be differentially expressed following ischemic injury, with the severity of the ischemic injury being affected by the upregulation or downregulation of certain types of lncRNA. The present review article provides an extensive summary of the functional roles of lncRNAs in ischemic injury, with a focus on the brain, heart, kidneys and lungs. The present review mainly summarizes the functional roles of lncRNA MALAT1, lncRNA MEG3, lncRNA H19, lncRNA TUG1, lncRNA NEAT1, lncRNA AK139328 and lncRNA CAREL, among which lncRNA MALAT1, in particular, plays a crucial role in ischemic injury and is currently a hot research topic.

Long non-coding RNA HAL suppresses the migration and invasion of serous ovarian cancer by inhibiting EMT signaling pathway

OBJECTIVE

To investigate the specific function of long non-coding RNA HAL in serous ovarian cancer (SOC) and to further clarify the regulation of HAL on EMT pathway.

MATERIALS AND METHODS

The expression of HAL and TWIST1 was detected by qRT-PCR. CCK8 assay, wound healing assay, transwell assay and flow cytometry were used to detect the HAL function on proliferation, migration, invasion and apoptosis in SOC cells. Western blot was used to calculate protein level of Vimentin, N-cadherin and E-cadherin. The effect of HAL on tumorigenesis of SOC was confirmed by xenograft nude mice model.

RESULTS

HAL was significantly decreased in SOC tissues and cells. Overexpression of HAL inhibited the proliferation, migration and invasion of SKOV3 cells, but promoted apoptosis. Furthermore, overexpression of HAL decreased the mRNA and protein levels of TWIST1 via a binding between HAL and TWIST1. Forced expression of TWIST1 reversed the inhibitory role of HAL on SOC cells' migration and invasion. The in vivo tumor growth assay showed that HAL suppressed SOC tumorigenesis with inhibiting EMT pathway.

CONCLUSIONS

Our research emphasized HAL acting as a tumor-inhibiting gene by regulating EMT signaling pathway, thus providing some novel experimental basis for clinical treatment of SOC.

LncRNA PVT1 Suppresses the Progression of Renal Fibrosis via Inactivation of TGF-β Signaling Pathway

BACKGROUND

Renal fibrosis is a frequent pathway leading to end-stage kidney dysfunction. In addition, renal fibrosis is the ultimate manifestation of chronic kidney diseases (CKD). Long noncoding RNAs (lncRNAs) are known to be involved in occurrence of renal fibrosis, and lncRNA plasmacytoma variant translocation 1 (PVT1) has been reported to act as a key biomarker in renal diseases. However, the role of PVT1 in renal fibrosis remains unclear.

MATERIALS AND METHODS

HK-2 cells were treated with TGF-β1 to mimic renal fibrosis in vitro. Gene and protein expressions in HK-2 cells were measured by qRT-PCR and Western-blot, respectively. ELISA was used to test the level of creatinine (CR) and blood urea nitrogen (BUN) in serum of mice. Additionally, unilateral ureteral obstruction (UUO)-induced renal fibrosis mice model was established to investigate the effect of PVT1 on renal fibrosis in vivo.

RESULTS

PVT1 was upregulated in TGF-β1-treated HK-2 cells. In addition, TGF-β1-induced upregulation of α-SMA and fibronectin in HK-2 cells was significantly reversed by PVT1 knockdown. Meanwhile, PVT1 bound to miR-181a-5p in HK-2 cells. Moreover, miR-181a-5p directly targeted TGF-βR1. Furthermore, miR-181a-5p antagonist could significantly reverse the anti-fibrotic effect of PVT1 knockdown. Besides, knockdown of PVT1 notably attenuated the symptom of renal fibrosis in vivo.

CONCLUSION

Knockdown of PVT1 significantly inhibited the progression of renal fibrosis in vitro and in vivo. Thus, PVT1 may serve as a potential target for the treatment of renal fibrosis.

Long non-coding RNA MALAT1 targeting STING transcription promotes bronchopulmonary dysplasia through regulation of CREB

Bronchopulmonary dysplasia (BPD) is a severe complication of preterm infants characterized by increased alveolarization and inflammation. Premature exposure to hyperoxia is believed to be a key contributor to the pathogenesis of BPD. No effective preventive or therapeutic agents have been created. Stimulator of interferon gene (STING) is associated with inflammation and apoptosis in various lung diseases. Long non-coding RNA MALAT1 has been reported to be involved in BPD. However, how MALAT1 regulates STING expression remains unknown. In this study, we assessed that STING and MALAT1 were up-regulated in the lung tissue from BPD neonates, hyperoxia-based rat models and lung epithelial cell lines. Then, using the flow cytometry and cell proliferation assay, we found that down-regulating of STING or MALAT1 inhibited the apoptosis and promoted the proliferation of hyperoxia-treated cells. Subsequently, qRT-PCR, Western blotting and dual-luciferase reporter assays showed that suppressing MALAT1 decreased the expression and promoter activity of STING. Moreover, transcription factor CREB showed its regulatory role in the transcription of STING via a chromatin immunoprecipitation. In conclusion, MALAT1 interacts with CREB to regulate STING transcription in BPD neonates. STING, CREB and MALAT1 may be promising therapeutic targets in the prevention and treatment of BPD.