Biophysical Characterization of G-Quadruplex Structure in Long Noncoding RNA NEAT1

Abstract

Paraspeckles are structures found in the interchromatin space of mammalian nuclei and are a relatively newly identified subnuclear body whose function is still largely unknown. Originally identified as being comprised of different paraspeckle proteins, it was later discovered that paraspeckles also contained RNA. Nuclear enriched abundant transcript 1 (NEAT1) is a long noncoding RNA (lncRNA) that has two different isoforms – NEAT1_1 and NEAT1_2, both of which are components of the paraspeckle. However, only NEAT1_2, consisting of around 22,700 nucleotides, has been found to be an essential component of paraspeckles, with each paraspeckle containing up to 50 NEAT1_2 molecules. FUS, a protein associated with amyotrophic lateral sclerosis (ALS), has been shown to be indispensable in the formation of paraspeckles, as these structures are not observed in FUS KO cells. FUS has been proposed to be implicated in maintaining the paraspeckle structure through its interactions with NEAT1; however, the molecular principles of recognition between FUS and NEAT1 are not known. FUS has been shown to bind G-quadruplex structures and in this study, we used biophysical methods such as NMR, CD, and UV spectroscopy to investigate if NEAT1 can form G-quadruplex structures that could be potentially recognized by FUS.