Hyperglycemia Induces Long Non-coding Rna Gas5 Expression Through The Ribosomal Binding Protein Hur
Junwang Xu, Junyi Hu, Carlos Zgheib, Maggie M. Hodges, Kenneth W. Liechty.
University of Colorado, Aurora, CO, USA.
Background: Diabetic wounds exhibit prolonged accumulation of macrophage with elevated levels of proinflammatory cytokines. We have previously shown that lncRNA GAS5 (Growth Arrest-Specific 5) was up-regulated in diabetic wounds, and the persistence of the proinflammatory macrophage (M1) phenotype was mediated partly by GAS5/STAT1 pathway, indicating a potential role for GAS5 in the pathogenesis of diabetic wounds. RNA binding protein HuR stabilizes mRNA by binding to 3’UTR of mRNA and inhibiting microRNA binding. We hypothesize that hyperglycemia induces GAS5 expression by alteration of HuR binding. Methods: To test our hypothesis, we incubated the murine macrophage cell line RAW264.7 with media containing 5 mM glucose (low glucose), or 25 mM glucose (high glucose) for 24 hours. RNA immunoprecipitation (RIP) was used to analyze HuR binding and Real-time PCR used to quantify relative gene expression. Results: GAS5 was significantly up-regulated in high glucose conditions. Under low glucose conditions, the level of GAS5 was not significantly different between the anti-HuR group and IgG control group. Under high glucose conditions, the level of GAS5 in the anti-HuR immunoprecipitated lysate was significantly higher than in the IgG control group. Discussion: These findings demonstrate a novel mechanism in the regulation of the effects of lncRNA GAS5 expression, with HuR binding to lncRNA GAS5 and hyperglycemia induces HuR binding to GAS5 to stabilize GAS5. Furthermore, these results may represent a potential novel therapeutic target to correct the impaired diabetic wound healing response.
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