MiRNA-29b Regulates Voltage-gated Potassium Channel 5(Kv1.5) in Human Pulmonary Arterial Smooth Muscle Cells under Hypoxic Conditions

Introduction: Pulmonary hypertension (PH) is a life-threatening disease that results in elevated pulmonary arterial pressure and heart failure if left untreated. The downregulated expression and activity of voltage-gated potassium (K + ) channels 1.5 (Kv1.5) in pulmonary arterial smooth muscle cells (PASMC) have been associated with the development of PH. Hypoxia induces PH and attenuates Kv1.5 channels; however, the precise mechanism is unknown. MicroRNA (miRNA) is a small non-coding RNA that binds to the 3’-untranslated regions (3’-UTR) of the mRNAs to regulate gene expression post-transcriptionally. We previously reported that miRNA-29b directly targets Kv1.5 in PASMC isolated from patients with PH. In this study, we hypothesized that the increased level of miRNA-29b is involved in hypoxia-induced downregulation of Kv1.5 channels to contribute to increased PASMC proliferation and the development of PH. Methods: Normal human PASMC was exposed to normoxia (21% O 2 ) or hypoxia (3% O 2 ) for 72 hours. MiRNA-29b or Kv1.5 expression was quantified by qPCR, Western blot, or immunostaining. EdU and Tunnel assays were used to assess PASMC proliferation and apoptosis, respectively. Cells were transfected with miR-29b mimic or inhibitor and exposed to normoxia or hypoxia, respectively for 72 hours. Results: Upregulated miRNA-29b was correlated with downregulated Kv1.5 level in PASMC exposed to hypoxia compared with normoxic cells. Additionally, hypoxia promoted PASMC survival by increasing proliferation and decreasing apoptosis. Transfection of cells with miRNA-29 mimic significantly increased expression of miRNA-29b compared with negative controls, while transfection of cells with miRNA-29 inhibitor dramatically reduced miRNA-29b level. Overexpression of miRNA-29b attenuated Kv1.5 channels under normoxic conditions to contribute to enhanced PASMC proliferation, whereas miRNA-29b inhibitor prevented Kv1.5 downregulation in response to hypoxia. Conclusions: Elevated miRNA-29b contributes to hypoxia-induced PASMC proliferation by targeting Kv1.5. Therefore, miRNA-29b inhibition can be a new therapeutic strategy to treat patients with hypoxia-induced PH or other types of PH. This study is supported by UMN-HI-Transformative Ideas Program (AB), Eagles Telethon Postdoctoral Fellowship (IE), and APS Summer Undergraduate Research Fellowship (KK). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.