Poster abstracts

Poster number 93 submitted by Cheryl Bolinger

Dissecting domains of RNA helicase A necessary for modulating translation of select lymphotropic retroviruses and cellular growth control genes

Cheryl G. Bolinger (Veterinary Biosciences, OSU), Kathleen Boris-Lawrie (Veterinary Biosciences, OSU)

Abstract:
RNA helicase A (RHA) is a DEIH box protein that is upregulated in multiple human cancers. In addition to it’s identification as a human tumor biomarker, our lab has found that RHA is necessary for translation of the cellular growth control gene, junD, and also several lymphotropic retroviruses, such as human T cell leukemia virus type 1. RHA is a nuclear-cytoplasmic shuttling protein although ~95% of steady-state RHA is found in the nucleus. RHA modulates gene transcription in the nucleus and mRNA translation in the cytoplasm. The translation response element of RHA is a 5’ terminal stem-loop structure termed the post-transcriptional control element (PCE). Our hypothesis is that RNA helicase A is recruited to PCE mRNA and arranges RNA-protein interactions to engage the protein synthesis machinery in the cytoplasm. We expect that regulation of RHA’s translational activity in the cytoplasm is crucial for appropriate expression of PCE-containing genes, which in turn control cell growth and virus production.
An essential step is to identify functional domains of RHA necessary for translation of PCE-containing mRNAs. RHA site-directed mutagenesis has been performed and the mutants are used in assays in which endogenous RHA is downregulated using siRNA. Mutational analyses of RHA has identified that the N-terminal double-stranded RNA binding domains are necessary for efficient polyribosome association and translation of HTLV-1 gag mRNA. We have identified a role for the C-terminal arginine-glycine-rich (RGG) domain that modulates nucleocytoplasmic shuttling activity of RHA and may be a possible single-stranded RNA binding domain. The RGG domain is critical for translation of HTLV-1 mRNA however RHA nuclear localization is not required.
The identification of RHA domains and characterization of trans-dominant RHA mutants that interfere with translational activity are necessary and critical steps towards the development of targeted treatments of retrovirus infection and cancers in which RHA is dysregulated.

Keywords: Translation, Retrovirus, Post-transcriptional control element