LncRNA TUG1 Repressed Angiogenesis by Promoting the Ubiquitination of HuR and Inhibiting Its Nuclear Translocation in Cerebral Ischemic Reperfusion Injury.

Abstract

Although both Taurine Upregulated Gene 1(TUG1) and Human Antigen R (HuR) play significant regulatory roles in Cerebral Ischemic Reperfusion Injury (CIRI), their potential pro-angiogenesis mechanisms in CIRI remain unclear.

Methods: Herein, the biological roles of TUG1 and HuR in angiogenesis are first confirmed. Following that, HuR-binding VEGFA mRNAs are identified via the Fluorescence In Situ Hybridization (FISH), RNA Immunoprecipitation (RIP), and Cross-Linking Immunoprecipitation (CLIP) assays. Actinomycin D and polysomal assays are also employed to confirm VEGFA mRNA stability. The co-localization of TUG1 with HuR is confirmed using FISH, while the RIP and RNA pull-down assays are employed to elucidate their interplay. The direct binding between TUG1 and HuR is confirmed through the CLIP assay. Co-Immunoprecipitation (Co-IP) and rescue experiments are performed to further elucidate TUG1-HuR interactions.

Results: While TUG1 repressed angiogenesis and aggravated CIRI, HuR exerted contrary effects. Specifically, HuR bound directly to VEGFA mRNA, a phenomenon that enhanced VEGFA mRNA stability. Conversely, TUG1 binds to HuR directly, inhibiting its nuclear translocation and promoting its ubiquitination, ultimately reducing VEGFA mRNA stability.

Conclusions: It is found that TUG1 can inhibit angiogenesis in CIRI through the HuR/VEGFA mRNA axis.