A cytoplasmic long noncoding RNA LINC00470 as a new AKT activator to mediate glioblastoma cell autophagy

Changhong Liu,Peiyao Li,Haijuan Fu,Yingnan Sun,Qiang Liu,Minghua Wu,Chunhua Zhao,Xiaoling She,Jianbo Feng,Li Fan,Qing Liu,Yan Zhang

doi:10.1186/s13045-018-0619-z

Abstract

BackgroundDespite the overwhelming number of investigations on AKT, little is known about lncRNA on AKT regulation, especially in GBM cells.MethodsRNA-binding protein immunoprecipitation assay (RIP) and RNA pulldown were used to confirm the binding of LINC00470 and fused in sarcoma (FUS). Confocal imaging, co-immunoprecipitation (Co-IP) and GST pulldown assays were used to detect the interaction between FUS and AKT. EdU assay, CCK-8 assay, and intracranial xenograft assays were performed to demonstrate the effect of LINC00470 on the malignant phenotype of GBM cells. RT-qPCR and Western blotting were performed to test the effect of LINC00470 on AKT and pAKT.ResultsIn this study, we demonstrated that LINC00470 was a positive regulator for AKT activation in GBM. LINC00470 bound to FUS and AKT to form a ternary complex, anchoring FUS in the cytoplasm to increase AKT activity. Higher pAKT activated by LINC00470 inhibited ubiquitination of HK1, which affected glycolysis, and inhibited cell autophagy. Furthermore, higher LINC00470 expression was associated with GBM tumorigenesis and poor patient prognosis.ConclusionsOur findings revealed a noncanonical AKT activation signaling pathway, i.e., LINC00470 directly interacts with FUS, serving as an AKT activator to promote GBM progression. LINC00470 has an important referential significance to evaluate the prognosis of patients.

Highlights

Despite the overwhelming number of investigations on AKT, little is known about lncRNA on AKT regulation, especially in GBM cells
We found that (1) LINC00470 is a positive regulator of AKT activation and it inhibited the nuclear translocation of phosphorylated AKT; (2) LINC00470 directly bound fused in sarcoma (FUS) and anchored FUS in the cytoplasm, resulting in FUS activation; (3) LINC00470 interacted with FUS and AKT to form a stable complex; and (4) LINC00470 decreased the ubiquitination of HK1, which affected glycolysis by positively regulating AKT activation in GBM tumorigenesis
LINC00470 was a positive regulator of AKT activities A vector construct containing the full-length LINC00470 with EGFP tag was developed and assessed for LINC00470 expression

Summary

Introduction

Despite the overwhelming number of investigations on AKT, little is known about lncRNA on AKT regulation, especially in GBM cells. Aberrant AKT activation causes a wide variety of disorders including diabetes, neurodegenerative syndromes, and various types of cancers. AKT is well established as the predominant PI3K effector in many cell types [5]. Many cancer genetic alterations deregulate cell signaling pathways and exert their oncogenic effects in part through the PI3K/AKT pathway [6, 7]. AKT can translocate from the plasma membrane to intracellular compartments, including the cytoplasm and nucleus where it phosphorylates substrates [9, 10]. Growth factors stimulate phosphorylated AKT to translocate from the cytoplasm to the nucleus [11] where AKT can be phosphorylated and activated [12]. Evidence indicates that a number of positive regulators, including regulatory proteins

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Conclusion