Adenoviral manipulation of arginine methylation

Project Summary:
As obligate intracellular pathogens, viruses must hijack cellular machinery to facilitate productive infection. For
DNA viruses that depend on host RNA processing machinery to produce viral transcripts, common targets of
manipulation include both cellular RNA-binding proteins (RBPs) and the enzymes mediating the post-
translational modifications (PTMs) that govern their functions. Arginine methylation is a PTM deposited by a
family of protein arginine methyltransferases (PRMTs) and involved in multiple aspects of RNA processing. While
the roles of arginine methylation and PRMTs constitute an emerging field in multiple areas of biology, relatively
little is known about their functions during viral infection. The objective of this project is to utilize human
Adenovirus (AdV) as a model system to address the roles of arginine methylation during infection. AdV is an
important human pathogen and also well recognized as a tool for investigating fundamental cellular processes.
Preliminary data from the Weitzman lab demonstrate an intriguing global decrease of arginine methylation on
cellular RBPs throughout AdV infection. Concurrently, arginine methylation of late region 4 (L4) 100 kDa
nonstructural protein (100K) dramatically increases as infection progresses. Furthermore, 100K expression is
sufficient to cause relocalization of PRMT1 from its normally nuclear subcellular compartment to the cytoplasm,
an event which correlates with a 100K-dependent loss of arginine methylation on cellular RBPs. Additionally,
methylation of the host RBP hnRNPA1 decreases in response to 100K expression alone. Arginine methylation
of hnRNPA1 is known to regulate its splicing capacity, and AdV is well known to manipulate host splicing
machinery, but knowledge of the role of hnRNPA1 during AdV infection is limited. These collective findings inform
my hypothesis that 100K acts as a molecular sponge of PRMT1 activity, leading to the loss of arginine
methylation of RBPs such as hnRNPA1, and thus regulating this splicing factor’s RNA-binding capacity and
function to promote efficient AdV splicing. In Aim 1 I will determine the requirement of 100K for PRMT
relocalization (confocal microscopy, IP-WB) and decreased hnRNPA1 methylation (isothermal calorimetry, MS-
based competition experiments). In Aim 2 I will determine if 100K impacts hnRNPA1 RNA-binding (eCLIP, RNA
Binding-Region Identification) and splicing abilities (qPCR-based splicing assays, molecular cloning, WB, plaque
assays) to benefit viral infection. This study will be the first to describe a mechanism of viral manipulation of
arginine methylation to promote infection. Results of this proposal will expand our understanding of how
pathogens interfere with PTM machinery, thus informing future studies to develop appropriate therapeutics
targeting arginine methylation to treat viral infections. This research will take place in the collaborative and
interdisciplinary environment of the Weitzman lab and the integrated communities of both the University of
Pennsylvania and the Children’s Hospital of Philadelphia. Skills gained from this training fellowship will prepare
me for a career as a principal investigator investigating molecular processes governing virus-host interactions.

Grant Number: 5F31AI181460-03
NIH Institute/Center: NIH
Principal Investigator: Amber Abbott