Long noncoding RNA HCG18 Promotes Extracellular Matrix Degradation of Nucleus Pulposus Cells in Intervertebral Disc Degeneration by Regulating the miR-4306/EPAS1 Axis

CircFUNDC1 interacts with CDK9 to promote mitophagy in nucleus pulposus cells under oxidative stress and ameliorates intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a leading cause of low back pain, with limited effective treatments due to an incomplete understanding of disease mechanisms. In this study, we report that circFUNDC1, a nuclear circular RNA, is markedly downregulated in nucleus pulposus cells (NPCs) from patients with end-stage IVDD. CircFUNDC1 is derived from the gene encoding the FUN14 domain-containing 1 (FUNDC1) protein, which is essential for mitophagy and cell survival. Functional analyses reveal that circFUNDC1 plays a crucial role in maintaining extracellular matrix homeostasis by enhancing the expression of anabolic factors in NPCs. Additionally, we identified the transcriptional regulator cyclin-dependent kinase 9 (CDK9) as a novel binding partner for circFUNDC1. Binding with circFUNDC1 recruits CDK9 via complementary nucleotides to the FUNDC1 promoter to stimulate the production of full-length FUNDC1 mRNAs and proteins, forming a positive feedback loop. Overexpression of circFUNDC1 protects NPCs from oxidative stress by promoting mitophagy, reducing reactive oxygen species levels, and inhibiting cellular senescence. Moreover, circFUNDC1 overexpression delays the onset of IVDD in an ex-vivo culture model. This study is the first to demonstrate that circFUNDC1 is vital for protecting NPCs from oxidative stress, suggesting circFUNDC1 as a potential therapeutic target for IVDD.

LncRNA HCG18 affects aortic dissection through the miR-103a-3p/HMGA2 axis by modulating proliferation and apoptosis of vascular smoothing muscle cells

BACKGROUND

Aortic Dissection (AD) is a vascular disease with a high mortality rate and limited treatment strategies. The current research analyzed the function and regulatory mechanism of lncRNA HCG18 in AD.

METHODS

HCG18, miR-103a-3p, and HMGA2 levels in the aortic tissue of AD patients were examined by RT-qPCR. After transfection with relevant plasmids, the proliferation of rat aortic Vascular Smoothing Muscle Cells (VSMCs) was detected by CCK-8 and colony formation assay, Bcl-2 and Bax was measured by Western blot, and apoptosis was checked by flow cytometry. Then, the targeting relationship between miR-103a-3p and HCG18 or HMGA2 was verified by bioinformation website analysis and dual luciferase reporter assay. Finally, the effect of HCG18 was verified in an AD rat model induced by β-aminopropionitrile.

RESULTS

HCG18 and HMGA2 were upregulated and miR-103a-3p was downregulated in the aortic tissues of AD patients. Downregulating HCG18 or upregulating miR-103a-3p enhanced the proliferation of VSMCs and limited cell apoptosis. HCG18 promoted HMGA2 expression by competing with miR-103a-3p and restoring HMGA2 could impair the effect of HCG18 downregulation or miR-103a-3p upregulation in mediating the proliferation and apoptosis of VSMCs. In addition, down-regulation of HCG18 could improve the pathological injury of the aorta in AD rats.

CONCLUSION

HCG18 reduces proliferation and induces apoptosis of VSMCs through the miR-103a-3p/HMGA2 axis, thus aggravating AD.

The role of lncRNA HCG18 in human diseases

A substantial number of long noncoding RNAs (lncRNAs) have been identified as potent regulators of human disease. Human leukocyte antigen complex group 18 (HCG18) is a new type of lncRNA that has recently been proven to play an important role in the occurrence and development of various diseases. Studies have found that abnormal expression of HCG18 is closely related to the clinicopathological characteristics of many diseases. More importantly, HCG18 was also found to promote disease progression by affecting a series of cell biological processes. This article mainly discusses the expression characteristics, clinical characteristics, biological effects and related regulatory mechanisms of HCG18 in different human diseases, providing a scientific theoretical basis for its early clinical application.