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Congenital heart disease (CHD) is the most common type of human innate malformation in fetuses. LncRNAs have been pointed to play critical regulatory roles in various types of cardiac development and diseases including CHD. Our study aimed to explore the effects of lncRNA forkhead box D3 antisense RNA 1 (FOXD3-AS1) on hypoxia-induced injury in AC16 cardiomyocytes and the related molecular mechanism. In vitro cell model of CHD was established by stimulating AC16 cells with hypoxia (1% O2). Expression of FOXD3-AS1 and miR-150-5p was detected by qRT-PCR. Hypoxia-induced injury was evaluated by detecting cell survival, lactate dehydrogenase (LDH) release, apoptosis, and caspase-3/7 activity using MTT, LDH assay, flow cytometry analysis, and caspase-3/7 activity assay, respectively. The regulatory relationship between FOXD3-AS1 and miR-150-5p was explored by luciferase reporter assay, RNA immunoprecipitation (RIP), and qRT-PCR. Results showed that hypoxia exposure caused an upregulation of FOXD3-AS1 and a downregulation of miR-150-5p in AC16 cells. Knockdown of FOXD3-AS1 attenuated reduction of cell survival and increase of LDH release, apoptosis, caspase-3/7 activity, and Bcl-2 associated X (Bax) expression induced by hypoxia in AC16 cells. Notably, we demonstrated that FOXD3-AS1 directly interacted with miR-150-5p to inhibit its expression. miR-150-5p knockdown reinforced the reduction of survival and induction of apoptosis by hypoxia and attenuated the effects of FOXD3-AS1 silencing on the same parameters in AC16 cells. In conclusion, FOXD3-AS1 knockdown protected AC16 cardiomyocytes from hypoxia-induced injury by increasing cell survival and inhibiting apoptosis through upregulating miR-150-5p. [ABSTRACT FROM AUTHOR]

Abstract Aims Aberrantly expressed miRNAs are demonstrated to be involved in the development of congenital heart disease (CHD). miR-9 was proposed to be upregulated in cardiac tissues from CHD cases. However, the role of miR-9 in hypoxia-induced cardiomyocytes and the potential mechanism are far from being addressed. Main methods qRT-PCR and western blot analysis were performed to detect miR-9 and Yes-associated protein 1 (Yap1) expressions in hypoxic H9c2 cells. CCK-8, flow cytometry analysis, caspase-3/7 activity assay were applied to evaluate cell proliferation, apoptosis, and caspase-3/7 activity, respectively. The interaction between miR-9 and Yap1 was explored by luciferase reporter assay, qRT-PCR and western blot. Key findings miR-9 was upregulated and Yap1 was downregulated in H9c2 cells in response to hypoxia in a time-dependent manner. Knockdown of miR-9 promoted cell proliferation, and inhibited apoptosis and caspase-3/7 activity in hypoxic H9c2 cells, while miR-9 overexpression exerted the opposite effects on hypoxic H9c2 cells. In addition, Yap1 was a direct target of miR-9 in H9c2 cells. Yap1 knockdown suppressed cell proliferation and promoted apoptosis in hypoxia-exposed H9c2 cells. Yap1 knockdown attenuated the effect of anti-miR-9 on cell proliferation and apoptosis in hypoxia-exposed H9c2 cells. Significance miR-9 knockdown inhibited hypoxia-induced cardiomyocyte apoptosis by targeting Yap1. Our study provided a novel insight into the mechanism of the adaptation of cardiomyocytes to chronic hypoxia. [ABSTRACT FROM AUTHOR]