The evolutionary conserved Taurine Upregulated Gene 1 (TUG1) is a ubiquitously expressed gene that is one of the highest expressed genes in human and rodent endothelial cells (ECs). We here show that TUG1 expression decreases significantly in aging mouse carotid artery ECs and human ECs in vitro, indicating a potential role in the aging endothelial vasculature system. We therefore investigated if, and how, TUG1 might function in aging ECs, but despite extensive phenotyping found no alterations in basal EC proliferation, apoptosis, barrier function, migration, mitochondrial function, or monocyte adhesion upon TUG1 silencing in vitro. TUG1 knockdown did slightly and significantly decrease cumulative sprout length upon vascular endothelial growth factor A stimulation in human umbilical vein endothelial cells (HUVECs), though TUG1-silenced HUVECs displayed no transcriptome-wide mRNA expression changes explaining this effect. Further, ectopic expression of the highly conserved and recently discovered 153 amino acid protein translated from certain TUG1 transcript isoforms did not alter angiogenic sprouting in vitro. Our data show that, despite a high expression and strong evolutionary conservation of both the TUG1 locus and the protein sequence it encodes, TUG1 does not seem to play a major role in basic endothelial cell function.
Background Cardiovascular diseases (CVDs) remain the leading cause of death worldwide. Hypoxia induces significant changes in cardiovascular control mechanisms potentially resulting in pathophysiology. Recently, an increasing number of long non-coding RNAs (lncRNAs) was reported to participate in the regulation of Hypoxia-inducible factors (HIF). Analysis of single-cell RNA-sequencing of human Abdominal Aortic Aneurysms pinpointed the endothelial-enriched lncRNA LINC01235. LINC01235 was previously correlated with tumour progression in gastric cancer and worse patient prognosis in breast cancer. Globally, the role of LINC01235 in the cardiovascular system remains unknown. Purpose The objective of this study is to unravel the function of LINC01235 in endothelial cells (ECs). Methods and results LINC01235 levels were elevated in human umbilical vein ECs (7.66 fold, p<0.05), human aortic ECs (16.84 fold, p<0.05) and human dermal microvascular ECs (639.73 fold, p<0.05) over other human cardiovascular cells like vascular smooth muscle cells, aortic fibroblasts and cardiomyocytes. Severe hypoxia (0.2% O2 for 24h) reduced LINC01235 expression significantly (0.33 fold, p<0.05). SiRNA-mediated LINC01235 silencing in HUVECs (0.12, p<0.05) resulted in decreased proliferation (0.76 fold, p<0.05) and vascular endothelial growth factor A (VEGFA)-stimulated angiogenic sprouting (0.39 fold, p<0.05). Loss of LINC01235 did not affect apoptosis, metabolism or barrier function. Analysis of RNA-sequencing data revealed that many hypoxia-responsive genes were downregulated after knockdown of LINC01235 (siCtrl vs. siLINC01235). These included HIF-3α (0.24 fold, p<5.86e-28) as a potential key regulator of the cellular feedback to hypoxia. Phenotypically, knockdown of HIF3A using siRNAs (0.07 fold, p<0.05) resulted in decreased proliferation (0.82 fold, p<0.05) and VEGFA-stimulated angiogenic sprouting (0.50 fold, p<0.05). Accordingly, hypoxia response and LINC01235 knockdown exhibit a negative correlation based on transcriptomics data (R=−0.157, p<2.2e-16), further emphasizing a role of LINC01235 in hypoxia response. Conclusion In summary, the EC-enriched lncRNA LINC01235 is likely required for the suppression of hypoxia-induced gene expression under normoxic conditions potentially mediated by HIF-3α. Functionally, loss of LINC01235 decreased proliferation and VEGFA-stimulated angiogenic sprouting without an effect on cell death, metabolism or barrier integrity. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): DFG - TRR267
The evolutionary conserved Taurine Upregulated Gene 1 ( TUG1 ) is a ubiquitously expressed gene that is one of the highest expressed genes in human and rodent endothelial cells (ECs). We here show that TUG1 expression decreases significantly in aging mouse carotid artery ECs and human ECs in vitro , indicating a potential role in the aging endothelial vasculature system. We therefore investigated if, and how, TUG1 might function in aging ECs, but despite extensive phenotyping found no alterations in basal EC proliferation, apoptosis, barrier function, migration, mitochondrial function, or monocyte adhesion upon TUG1 silencing in vitro . TUG1 knockdown did slightly and significantly decrease cumulative sprout length upon vascular endothelial growth factor A stimulation in human umbilical vein endothelial cells (HUVECs), though TUG1-silenced HUVECs displayed no transcriptome-wide mRNA expression changes explaining this effect. Further, ectopic expression of the highly conserved and recently discovered 153 amino acid protein translated from certain TUG1 transcript isoforms did not alter angiogenic sprouting in vitro . Our data show that, despite a high expression and strong evolutionary conservation of both the TUG1 locus and the protein sequence it encodes, TUG1 does not seem to play a major role in basic endothelial cell function.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.