Conditional Knockout of Tumor Overexpressed Gene in Mouse Neurons Affects RNA Granule Assembly, Granule Translation, LTP and Short Term Habituation

Elisa Barbarese,Jessica W Tutolo,Eric Levine,Xin-Ming Ma,Vedakumar Tatavarty,Marius F Ifrim,George Korza,Lawrence Hsieh,Duck O Kim,John H Carson,Anthony Giampetruzzi,Shigeyuki Kuwada,Hien Le,Michael J Maggipinto,Caiying Guo,Brian Bishop

doi:10.1371/journal.pone.0069989

Elisa Barbarese, Jessica W Tutolo + Show 14 more

Open Access

https://doi.org/10.1371/journal.pone.0069989

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Journal: PloS one	Publication Date: Aug 6, 2013
Citations: 12	License type: CC BY 4.0

Affiliation: University of Connecticut Health Center

Abstract

In neurons, specific RNAs are assembled into granules, which are translated in dendrites, however the functional consequences of granule assembly are not known. Tumor overexpressed gene (TOG) is a granule-associated protein containing multiple binding sites for heterogeneous nuclear ribonucleoprotein (hnRNP) A2, another granule component that recognizes cis-acting sequences called hnRNP A2 response elements (A2REs) present in several granule RNAs. Translation in granules is sporadic, which is believed to reflect monosomal translation, with occasional bursts, which are believed to reflect polysomal translation. In this study, TOG expression was conditionally knocked out (TOG cKO) in mouse hippocampal neurons using cre/lox technology. In TOG cKO cultured neurons granule assembly and bursty translation of activity-regulated cytoskeletal associated (ARC) mRNA, an A2RE RNA, are disrupted. In TOG cKO brain slices synaptic sensitivity and long term potentiation (LTP) are reduced. TOG cKO mice exhibit hyperactivity, perseveration and impaired short term habituation. These results suggest that in hippocampal neurons TOG is required for granule assembly, granule translation and synaptic plasticity, and affects behavior.

Highlights

Tumor overexpressed gene (TOG), the product of the CKAP5 gene, is a long filamentous protein comprised of reiterated TOG domains, each consisting of multiple HEAT repeats [1,2]
TOG expression was conditionally knocked out (TOG cKO) in hippocampal neurons Floxed TOG transgenic mice were produced using recombineering techniques [36]
We propose that the primary TOG-dependent phenotype is disruption of granule assembly and that other phenotypes reflect downstream granule-dependent processes

Summary

Introduction

TOG, the product of the CKAP5 gene, is a long filamentous protein comprised of reiterated TOG domains, each consisting of multiple HEAT repeats [1,2]. TOG was shown to bind to hnRNP A2 [7] a cognate trans-acting RNA binding protein that recognizes cisacting sequences called hnRNP A2 response elements (A2REs) in dendritically localized RNAs encoding proteins. These include: a calcium/calmodulin-dependent protein kinase (aCaMKII), neurogranin (NG), activity-regulated cytoskeleton associated (ARC) protein, and protein kinase M zeta (PKMj), all of which are required for regulation of synaptic function in neurons [8]. ARC RNA was used as a reporter RNA for granule assembly and translation in control and TOG cKO neurons because it contains an A2RE sequence, is incorporated into granules and exhibits bursty translation in hippocampal neurons [8,11,12,13]. Our results indicate that TOG expression in neurons affects granule assembly, bursty translation, synaptic function and behavior

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