Early Evidence for the Role of lncRNA TUG1 in Vascular Remodelling in Pulmonary Hypertension

The Long-Noncoding RNA TUG1 Regulates Oxygen-Induced Retinal Neovascularization in Mice via MiR-299

Purpose

The oxygen-induced retinal neovascularization mouse model closely approximates pathological changes associated with human retinal neovascularization-associated diseases, including retinopathies. We used this model and human retinal endothelial cells (HRECs) under hypoxia to explore the relationship between taurine upregulated gene-1 (TUG1), vascular endothelial growth factor (VEGF), and miR-299-3p on retinopathy of prematurity (ROP).

Methods

An oxygen-induced retinopathy (OIR) mouse model was established; the mice were divided into a normal control group, OIR group, TUG1 control group (lentivirus control), and TUG1-knockdown group. The apoptosis of retinal cells was evaluated using a TUNEL assay. Angiogenic, apoptotic, and inflammatory factors were detected by Western blot, immunohistochemistry, and immunofluorescence analyses. HRECs were cultured under hypoxia and assessed for VEGF expression, apoptosis, tubule formation, and migration ability. The relationship between TUG1, VEGF, and miR-299-3p was detected via a dual luciferase reporter gene assay.

Results

Intravitreal injection of TUG1 lentivirus reduced the inflammatory response in the mouse retinal tissue and markedly reduced pathological changes in the retina. Overexpression of miR-299 in HRECs reduced the apoptosis rate, tube formation, and migration ability of hypoxia-treated cells, thereby inhibiting the formation of new blood vessels. The dual luciferase reporter gene assay suggested that miR-299 has binding sites for TUG1 and VEGF.

Conclusions

TUG1 reduces the expression of VEGFA by competitively adsorbing miR-299-3p and facilitates the regulation of retinal neovascularization, suggesting that it may serve as a new therapeutic target for retinal neovascular diseases.

Construction and analysis of the abnormal lncRNA-miRNA-mRNA network in hypoxic pulmonary hypertension

The incidence of hypoxic pulmonary hypertension (HPH) is increasing. Accumulating evidence suggests that long noncoding RNAs (lncRNAs) play an important role in HPH, but the functions and mechanism have yet to be fully elucidated. In the present study, we established a HPH rat model with 8 h of hypoxia exposure (10% O2) per day for 21 days. High-throughput sequencing identified 60 differentially expressed (DE) lncRNAs, 20 DE miRNAs and 695 DE mRNAs in rat lung tissue. qRT-PCR verified the accuracy of the results. The DE mRNAs were significantly enriched in immune response, inflammatory response, leukocyte migration, cell cycle, cellular response to interleukin-1, IL-17 signalling pathway, cytokine-cytokine receptor interaction and Toll-like receptor signalling pathway. According to the theory of competing endogenous RNA (ceRNA) networks, lncRNA-miRNA-mRNA network was constructed by Cytoscape software, 16 miRNAs and 144 mRNAs. The results suggested that seven DE lncRNAs (Ly6l, AABR07038849.2, AABR07069008.2, AABR07064873.1, AABR07001382.1, AABR07068161.1 and AABR07060341.2) may serve as molecular sponges of the corresponding miRNAs and play a major role in HPH.

LncRNA PAXIP1-AS1 fosters the pathogenesis of pulmonary arterial hypertension via ETS1/WIPF1/RhoA axis

Pulmonary arterial hypertension (PAH) is a life‐threatening disease featured with elevated pulmonary vascular resistance and progressive pulmonary vascular remodelling. It has been demonstrated that lncRNA PAXIP1‐AS1 could influence the transcriptome in PAH. However, the exact molecular mechanism of PAXIP1‐AS1 in PAH pathogenesis remains largely unknown. In this study, in vivo rat PAH model was established by monocrotaline (MCT) induction and hypoxia was used to induce in vitro PAH model using human pulmonary artery smooth muscle cells (hPASMCs). Histological examinations including H&E, Masson's trichrome staining and immunohistochemistry were subjected to evaluate the pathological changes of lung tissues. Expression patterns of PAXIP1‐AS1 and RhoA were assessed using qRT‐PCR and Western blotting, respectively. CCK‐8, BrdU assay and immunofluorescence of Ki67 were performed to measure the cell proliferation. Wound healing and transwell assays were employed to evaluate the capacity of cell migration. Dual‐luciferase reporter assay, co‐immunoprecipitation, RIP and CHIP assays were employed to verify the PAXIP1‐AS1/ETS1/WIPF1/RhoA regulatory network. It was found that the expression of PAXIP1‐AS1 and RhoA was remarkably higher in both lung tissues and serum of MCT‐induced PAH rats, as well as in hypoxia‐induced hPASMCs. PAXIP1‐AS1 knockdown remarkably suppressed hypoxia‐induced cell viability and migration of hPASMCs. PAXIP1‐AS1 positively regulated WIPF1 via recruiting transcriptional factor ETS1, of which knockdown reversed PAXIP1‐AS1‐mediated biological functions. Co‐immunoprecipitation validated the WIPF1/RhoA interaction. In vivo experiments further revealed the role of PAXIP1‐AS1 in PAH pathogenesis. In summary, lncRNA PAXIP1‐AS1 promoted cell viability and migration of hPASMCs via ETS1/WIPF1/RhoA, which might provide a potential therapeutic target for PAH treatment.

LncRNA HOXA-AS3 Promotes the Progression of Pulmonary Arterial Hypertension through Mediation of miR-675-3p/PDE5A Axis

Pulmonary arterial hypertension (PAH) seriously threatens the elder people. Long non-coding RNAs (lncRNAs) are involved in multiple diseases. However, the study of the lncRNAs in the occurrence of PAH is just beginning. For this, we sought to explore the biological function of lncRNA HOXA cluster antisense RNA 3 (HOXA-AS3) in PAH. Hypoxia (HYP) was used to mimic in vitro model of PAH. Gene and protein expressions in cells were detected by q-PCR and Western blotting, respectively. In addition, cell proliferation and viability were tested by CCK-8 and MTT assay. Cell apoptosis was measured by flow cytometry. Wound healing was used to detect cell migration. Furthermore, the connection of HOXA-AS3, miR-675-3p, and phosphodiesterase 5A (PDE5A) was verified by dual-luciferase report assay. HOXA-AS3 and PDE5A were upregulated in human pulmonary artery smooth muscle cells (HPASMCs) in the presence of HYP, while miR-675-3p was downregulated. Moreover, knockdown of HOXA-AS3 suppressed the growth and migration of HPASMCs, but induced the apoptosis. Overexpression of miR-675-3p achieved the same effect. MiR-675-3p inhibitor or overexpression of PDE5A notably reversed the inhibitory effect of HOXA-AS3 knockdown on PAH. Finally, HOXA-AS3 could sponge miR-675-3p, and PDE5A was directly targeted by miR-675-3p. HOXA-AS3 increased the development of PAH via regulation of miR-675-3p/PDE5 axis, which could be the potential biomarker for treatment of PAH.

Cell Tracking Suggests Pathophysiological and Therapeutic Role of Bone Marrow Cells in Sugen5416/Hypoxia Rat Model of Pulmonary Arterial Hypertension

BACKGROUND

The mechanism of vascular remodelling in pulmonary arterial hypertension (PAH) remains unclear. Hence, defining the origin of cells constituting intractable vascular lesions in PAH is expected to facilitate therapeutic progress. Herein, we aimed to evaluate the origin of intractable vascular lesions in PAH rodent models via bone marrow (BM) and orthotopic lung transplantation (LT).

METHODS

To trace BM-derived cells, we prepared chimeric rats transplanted with BM cells from green fluorescent protein (GFP) transgenic rats. Male rats were transplanted with lungs obtained from female rats and vice versa. Pulmonary hypertension was induced in the transplanted rats via Sugen5416 treatment and subsequent chronic hypoxia (Su/Hx).

RESULTS

In the chimeric Su/Hx models, GFP-positive cells were observed in the pulmonary vascular area. Moreover, the right ventricular systolic pressure was significantly lower compared with wild-type Su/Hx rats without BM transplantation (P = 0.009). PAH suppression was also observed in rats that received allograft transplanted BM transplantation. In male rats that received LT and Su/Hx, BM-derived cells carrying the Y chromosome were also detected in neointimal occlusive lesions of the transplanted lungs received from female rats.

CONCLUSIONS

BM-derived cells participate in pulmonary vascular remodelling in the Su/Hx rat model, whereas BM transplantation may contribute to suppression of development of PAH.