GAS5 promotes myocardial apoptosis in myocardial ischemia-reperfusion injury via upregulating LAS1 expression

Cardiac fibroblasts secrete exosome microRNA to suppress cardiomyocyte pyroptosis in myocardial ischemia/reperfusion injury

Molecular mechanisms underlying myocardial ischemia/reperfusion (MI/R) injury and effective strategies to treat MI/R injury are both in shortage. Although pyroptosis of cardiomyocytes and the protective role of cardiac fibroblasts (CFs) have been well recognized as targets to reduce MI/R injury and sudden cardiac death (SCD), the connection has not yet been established. Here, we showed that CFs protected cardiomyocytes against MI/R-induced injury through suppression of pyroptosis. A novel molecular mechanism underpinning this effect was further identified. Under hypoxia/reoxygenation condition, CFs were found to secrete exosomes, which contain increased level of microRNA-133a (miR-133a). These exosomes then delivered miR-133a into cardiomyocytes to target ELAVL1 and repressed cardiomyocyte pyroptosis. Based on this finding, we successfully developed a new strategy that used exosomes derived from CFs with overexpressed miR-133a to enhance the therapeutic outcomes for the MI/R injury. Overall, our results provide a novel molecular basis for understanding and treating MI/R injury, and our study also provides novel insight for the postmortem diagnosis of MI/R injury induced SCD by using exosome biomarker in forensic.

Long‑chain non‑coding RNA GAS5 promotes cell autophagy by modulating the miR‑181c‑5p/ATG5 and miR‑1192/ATG12 axes

The main aim of the present study was to explore the role of long-chain non-coding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5) in macrophage autophagy. Firstly, the expression of lncRNA GAS5 during cell starvation or following treatment with 3-methyladenine was determined using reverse transcription-quantitative PCR (RT-qPCR). Additionally, fluorescent in situ hybridization (FISH) assay was utilized to determine the localization of the expression of lncRNA GAS5 in RAW264.7 cells. In vitro cell models were established through the transfection of LV5-lncRNA GAS5 (LV5-GAS5) or LV3-shRNA-lnc GAS5 (sh-GAS5), in order to overexpress or knockdown lncRNA GAS5 expression in RAW264.7 cells. The potential target microRNAs (miRNAs/miRs) of lncRNA GAS5 were analyzed using bioinformatics. The formation of autophagic bodies was detected with the use of laser confocal and transmission electron microscopy. Dual-luciferase reporter assay was performed to determine the target specificities of miR-181c-5p or miR-1192 to lncRNA GAS5 and autophagy-related gene (ATG) or ATG12. The mRNA levels of miR181c-5p, miR-1192, as well as ATG5 and ATG12 were detected using RT-qPCR. The protein levels of microtubule-associated proteins 1A/1B light chain 3B (LC3), p62, ATG5 and ATG12 were measured using western blot analysis. It was revealed that lncRNA GAS5 expression in RAW264.7 macrophages increased significantly during starvation-induced autophagy, and that lncRNA GAS5 overexpression was able to markedly promote the formation of autophagic bodies. Bioinformatics analysis demonstrated that miR-181c-5p and miR-1192 were potential targets of lncRNA GAS5, which was further confirmed by RT-qPCR, western blot analysis and the dual-luciferase reporter assay. Finally, it was confirmed that lncRNA GAS5 promoted autophagy by sponging miR-181c-5p and miR-1192, and upregulating the expression levels of the key autophagic regulators, ATG5 and ATG12. On the whole, the present study demonstrates that total, lncRNA GAS5 promotes macrophage autophagy by targeting the miR-181c-5p/ATG5 and miR-1192/ATG12 axes.

The interplay between HIF-1α and long noncoding GAS5 regulates the JAK1/STAT3 signalling pathway in hypoxia-induced injury in myocardial cells

Background

Long non-coding RNA (lncRNA) GAS5 is associated with hypoxia-induced diseases whereas hypoxia-inducible factor-1α (HIF-1α) plays an important role in hypoxic injury of cells. The current study explores the regulatory functions of GAS5/HIF-1α which co-play in anoxic injury among rat cardiomyocytes H9C2 cells.

Methods

Hypoxia in vitro model was established through anoxic incubation while normal culture of H9C2 cells was considered as control. The expression levels of GAS5 and HIF-1α were quantified through RT-qPCR. CCK-8 was applied to determine cell viability. Cell apoptosis rate was calculated using flow cytometry whereas inflammatory cytokines were detected using ELISA method. The impact of downregulating GAS5 or HIF-1α or both upon hypoxic cells was assessed on the basis of changes in cell viability, apoptosis, and inflammatory response. The activity of JAK1/STAT3 signaling was evaluated through RT-qPCR for mRNA expression. AG490 was introduced to inactivate JAK1/STAT3 pathway and to unveil the impact of JAK1/STAT3 signaling on GAS5/HIF-1α and cell viability, apoptosis and inflammation in hypoxic cells.

Results

The results infer that hypoxia suppressed cell viability, promoted inflammation and apoptosis among H9C2 cells. GAS5 or HIF-1α recorded higher expression in hypoxia-induced cells whereas the cell viability got restored with reduction in inflammation and apoptosis. The downregulation of HIF-1α enhanced the protective effect of knocking down GAS5 in hypoxia H9C2 cells. JAK1/STAT3 signaling pathway got activated in hypoxic cells and was regulated by GAS5 and HIF-1α. The inhibition of signaling pathway increased the cell viability but it decreased both inflammation and apoptosis.

Conclusions

GAS5 and HIF-1α could regulate hypoxic injury in H9C2 cells through JAK1/STAT3 signaling pathway. This scenario suggests that the inhibitors of GAS5 and HIF-1α may synergize with AG-490 to protect myocardial cells from hypoxic injury.

Long non-coding RNA GAS5 suppresses rheumatoid arthritis progression via miR-128-3p/HDAC4 axis

Rheumatoid arthritis (RA) is a highly relevant public health problem. RA fibroblast-like synoviocytes (RAFLSs) play an important role in RA progression. Long non-coding RNA growth arrest-specific transcript 5 (GAS5) could improve RA by inducing RAFLSs apoptosis. However, the mechanism of GAS5 in RA remains unclear. RT-qPCR detected the expressions of GAS5, microRNA-128-3p (miR-128-3p), and histone deacetylase 4 (HDAC4) in RA synovial tissues and RAFLSs. Proliferation, apoptosis, migration, and invasion were measured by Cell Counting Kit-8 assay (CCK-8), flow cytometry, and transwell assays, severally. The protein levels of B-cell lymphoma-2 (Bcl-2), C-caspase 3, Bcl-2 related X protein (Bax), Tumor Necrosis factor-α (TNF-α), Interleukin 6 (IL-6), Interleukin 17 (IL-17), HDAC4, phosphorylation-protein kinase B (p-AKT), AKT, a phosphorylation-mechanistic target of rapamycin (p-mTOR), and mTOR were assessed by western blot assay. The interaction between miR-128-3p and GAS5 or HDAC4 was predicted by ENCORI or TargetScan Human and verified by the dual-luciferase reporter, RNA Immunoprecipitation (RIP), and RNA pull-down assays. GAS5 and HDAC4 were downregulated, and miR-128-3p was upregulated in RA synovial tissues and RAFLSs. Function analysis indicated that GAS5 curbed proliferation, migration, invasion, inflammation, and facilitated apoptosis of RAFLSs. Rescue assay confirmed that miR-128-3p overexpression or HDAC4 knockdown weakened the inhibitory effect of GAS5 or anti-miR-128-3p on RA development. GAS5 acted as a miR-128-3p sponge to upregulate HDAC4 expression. Besides, GAS5/miR-128-3p/HDAC4 axis regulated RA progression partially through the AKT/mTOR pathway. Our studies disclosed that GAS5 restrained inflammation in synovial tissue partly through regulating HDAC4 via miR-128-3p, suggesting a potential lncRNA-targeted therapy for RA treatment.

Expression of long-chain noncoding RNA GAS5 in osteoarthritis and its effect on apoptosis and autophagy of osteoarthritis chondrocytes

OBJECTIVE

To investigate the expression of long-chain noncoding RNA GAS5 in osteoarthritis (OA) and the effect of silencing GAS5 on autophagy of osteoarthritis chondrocytes (OACs).

METHODS

OA rat models were constructed by cutting the anterior cruciate ligament, and the expressions of GAS5 in rat cartilage tissues at 4 weeks (early OA) and 12 weeks (late OA) after modeling were detected. The rat chondrocytes were isolated, cultured and transfected with si-GAS5 to silencing GAS5. Then, the changes of apoptosis and autophagy levels of OA chondrocytes were detected by transfection of GFP-LC3 and flow cytometry. Bioinformatic tools were used to analyze the miRNA binding to GAS5 and the downstream target genes, then luciferase reporter assay and GDC-0349 (inhibitor of mTOR) were used to verify their relationships.

RESULTS

The expression of GAS5 in cartilage tissue of OA rats was higher than control, which was higher in late OA than that in early OA. After silencing the GAS5, the autophagy ability of OACs was increased and the apoptosis rate was decreased. GAS5 was able to bind to miR-144 and regulate the expressin of mTOR. mTOR inhibitor GDC-0349 could reverse the inhibition of GAS5 on autophagy but could not reverse its effect on apoptosis.

CONCLUSION

GAS5 expresses highly in OA cartilage tissues and increases with the progression of OA. GAS5 inhibits autophagy and promotes the apoptosis of OACs, and the inhibition of autophagy may be related to its regulation of mTOR.

GAS5‑mediated regulation of cell signaling (Review)

In recent years, an increasing number of long non-coding RNAs (lncRNAs) have been discovered using microarrays and nucleic acid sequencing technology. LncRNAs exert crucial biological functions by regulating signaling pathways. In particular, the lncRNA growth arrest-specific transcript 5 (GAS5) has been documented to serve a crucial role in numerous signaling pathways. This article discusses the latest developments in the association between GAS5 and microRNA (miRNA), p53, mTOR, glucocorticoid response element (GRE) and AKT in order to investigate the roles served by GAS5. miRNAs can activate related signaling pathways and GAS5 can combine with miRNA to regulate related signaling pathways. GAS5 may regulate p53 expression via derivation of snoRNA, but the underlying mechanism requires further investigation. GAS5 overxpresion reduces the expression level of mTOR, which is induced by inhibiting miR-106a-5p expression. GAS5 is a sponge of GR, and serves a role in controlling and maintaining glucocorticoid sensitivity and drug resistance via competitive combination with GR. GAS5 can interact with miRNAs, such as miR-21 and miR-532-5p, to regulate the expression of AKT signaling pathway, affecting cell survival and apoptosis. Collectively, the data indicate that GAS5 serves a key role in the miRNA, p53, mTOR, GRE, and AKT signaling pathways. GAS5 regulates complex intracellular signaling pathways primarily through three modes of action, all of which are interrelated: Signal, decoy and guide. In the present article, latest developments in the association between GAS5 and a number of cellular signaling pathways are discussed to examine the tumor suppressive role of GAS5.

Long non‑coding RNA GAS5 regulates myocardial ischemia‑reperfusion injury through the PI3K/AKT apoptosis pathway by sponging miR‑532‑5p

Long non‑coding RNAs (lncRNAs) have been revealed to have a marked effect in cardiovascular diseases, including during cardiac development, cardiac hypertrophy, myocardial fibrosis and myocardial ischemic injury. The mechanism of myocardial ischemia‑reperfusion injury (MIRI) is very complicated. Although studies have confirmed that lncRNAs are involved, the specific mechanism remains largely unknown. The lncRNA growth arrest specific 5 (GAS5) is known as a regulator of a number of diseases, including certain cancer types. The present study aimed to investigate the function of lncRNA GAS5 in MIRI. The present study reported that the expression of lncRNA GAS5 in H9c2 cells treated with anoxia and reoxygenation was significantly upregulated compared with the control group (P<0.05). Similarly, the expression of lncRNA GAS5 in myocardial tissue obtained from rats treated with MIRI was significantly upregulated compared with the untreated controls (P<0.05). Silencing of lncRNA GAS5 was able to attenuate myocardial damage, as cell viability increased and the apoptosis rate decreased. Classical apoptotic proteins involved in MIRI, including B‑cell lymphoma 2, Bcl‑2‑associated X protein and cleaved caspase‑3, also exhibited the same trend. At the same time, when lncRNA GAS5 was silenced, microRNA (miR)‑532‑5p, which was originally expressed at the stage of injury, was upregulated. The luciferase reporter assay results indicated that the lncRNA GAS5 functioned as a molecular sponge of miR‑532‑5p. The gain‑ and loss‑of‑function analysis of miR‑532‑5p indicated that it was involved in the regulation of MIRI; the trend of results following its overexpression was also consistent with the trend observed following the silencing of lncRNA GAS5. Notably, the protective effect of lncRNA GAS5 silencing on cells was attenuated by miR‑532‑5p inhibition. Phosphatase and tensin homolog was revealed to be a key target gene for the function of lncRNA GAS5, and its regulation was achieved via binding to miR‑532‑5p. In other words, silencing lncRNA GAS5 ultimately promoted the activation of the phosphoinositide‑3‑kinase (PI3K)/protein kinase B pathway (AKT) to reduce myocardial damage. Therefore, lncRNA GAS5 was able to regulate MIRI through the PI3K/AKT apoptosis pathway by sponging miR‑532‑5p.

Down-regulation of GAS5 ameliorates myocardial ischaemia/reperfusion injury via the miR-335/ROCK1/AKT/GSK-3β axis

Growth arrest‐specific transcript 5 (GAS5), along non‐coding RNA (LncRNA), is highly expressed in hypoxia/reoxygenation (H/R)‐cardiomyocytes and promotes H/R‐induced apoptosis. In this study, we determined whether down‐regulation of GAS5 ameliorates myocardial ischaemia/reperfusion (I/R) injury and further explored its mechanism. GAS5 expression in cardiomyocytes and rats was knockdown by transfected or injected with GAS5‐specific small interfering RNA or adeno‐associated virus delivering small hairpin RNAs, respectively. The effects of GAS5 knockdown on myocardial I/R injury were detected by CCK‐8, myocardial enzyme test, flow cytometry, TTC and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) staining. qRT‐PCR and luciferase reporter assay were carried out to analyse the relationship between GAS5 and miR‐335. The regulation of GAS5 on Rho‐associated protein kinase 1 (ROCK1) expression, the activation of PI3K/AKT/GSK‐3β pathway and mitochondrial permeability transition pore (mPTP) opening was further evaluated. The results indicated that GAS5 knockdown enhanced the viability, decreased apoptosis and reduced the levels of lactate dehydrogenase and creatine kinase‐MB in H/R‐treatment cardiomyocytes. Meanwhile, down‐regulation of GAS5 limited myocardial infarct size and reduced apoptosis in I/R‐heart. GAS5 was found to bind to miR‐335 and displayed a reciprocal inhibition between them. Furthermore, GAS5 knockdown repressed ROCK1 expression, activated PI3K/AKT, thereby leading to inhibition of GSK‐3β and mPTP opening. These suppressions were abrogated by miR‐335 inhibitor treatment. Taken together, our results demonstrated that down‐regulation of GAS5 ameliorates myocardial I/R injury via the miR‐335/ROCK1/AKT/GSK‐3β axis. Our findings suggested that GAS5 may be a new therapeutic target for the prevention of myocardial I/R injury.