LINC00599 Promotes Pulmonary Hypertension via LLPS with G3BP1 and MYH9

BACKGROUNDPulmonary hypertension (PH) represents a significant cardiovascular disorder marked by both functional and structural alterations within the pulmonary vasculature. Long non-coding RNAs (lncRNAs) have been closely associated with the pathogenesis and progression of PH. Nonetheless, the precise mechanisms by which lncRNAs interact with its downstream target molecules to modulate the disease remain inadequately elucidated. METHODSThe expression levels of LINC00599 were quantified in the lung tissues of mice and pulmonary arterial smooth muscle cells (PASMCs) under hypoxic conditions. The involvement of LINC00599 in the progression of PH and vascular remodeling was evaluated through in vivo studies. To investigate the mechanisms by which LINC00599 influences the proliferation of human PASMCs, small interfering RNA and overexpression plasmids were employed. RESUITSThe expression of LINC00599 is upregulated in the medial layer of pulmonary arteries in experimental models of PH and in hypoxic PASMCs. Administration of a single dose of lentivirus-mediated shRNA targeting LINC00599 effectively reverses hypoxic PH in murine models. LINC00599 plays a critical role in PASMC proliferation by modulating stress granule formation through N6-methyladenosine (m6A) modification and promoting proliferation via liquid-liquid phase separation with myosin heavy chain 9. Furthermore, the expression of LINC00599 is regulated by a super-enhancer, which is mediated by the transcription factor ZNF263. CONCLUSIONSThese findings demonstrate for the first time that LINC00599, involved in liquid-liquid phase separation, facilitates the progression of pulmonary hypertension by enhancing the proliferation of pulmonary artery smooth muscle cells. GRAPHIC ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=158 SRC="FIGDIR/small/629439v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@7ac192org.highwire.dtl.DTLVardef@13a88b3org.highwire.dtl.DTLVardef@1e4c761org.highwire.dtl.DTLVardef@ddd105_HPS_FORMAT_FIGEXP M_FIG C_FIG What Is New?This study identified LINC00599 as a critical regulator of liquid-liquid phase separation through m6A modification and as a pivotal target in promoting the progression of PH. What Is Relevant?LncRNAs are intricately associated with the pathogenesis and progression of PH through the modulation of downstream target molecules. However, it remains unclear whether lncRNAs contribute to PH by forming specific subcellular structures with these target molecules. Furthermore, some studies have suggested that the increased presence of stress granules in PASMCs is implicated in the pathogenesis of pulmonary arterial hypertension. In this study, we provide evidence that LINC00599 promotes the development of PH by forming stress granules with its target proteins. Our findings indicate that the binding of LINC00599, modified with m6A, to G3BP1 and MYH9 in PASMCs suggests that the regulation of liquid-liquid phase separation by lncRNA m6A modification may represent a significant pathological mechanism underlying PH. What Are the Pathophysiological Implications?We found that LINC00599 levels were elevated in hypoxic PASMCs and experimental PH models. Knockout LINC00599 effectively prevented PH, indicating its potential as both a bomarker and therapeutic target for PH.