RNA-based mechanisms in nuclear steps of gene expression

Project Summary
RNA-RNA and RNA-protein interactions lie at the heart of essential steps of the eukaryotic gene
expression pathway. Defects in these interactions due to inherited mutations can result in age-
dependent degeneration of the retina, motor neurons, and other neural tissues. The proposed
studies will result in a better understanding of RNA-based mechanisms of gene expression in
both the normal and disease states. In the next five years we will pursue three main goals, using
the yeast Saccharomyces cerevisiae as a facile model system. First, we will examine the
molecular mechanism of activation of the spliceosome for the first catalytic step of pre-mRNA
splicing. This process requires allosteric signal transmission through RNA and protein over
distances of 100 angstroms or more and results in large-scale remodeling of the spliceosome to
allow progression of the splicing cycle. Second, we will elucidate the basis for regulation of
expression of a key enzyme in purine nucleotide metabolism, IMPDH, interrogating both
transcriptional and post-transcriptional steps. Inherited alterations in a regulatory domain of
IMPDH and in proteins that direct spliceosome activation are associated with autosomal
dominant retinitis pigmentosa, which leads to progressive blindness. We will look for
commonalities between the two processes that might explain the highly specific pathological
consequences of these disease mutations. Third, we will examine the functions of the hnRNP
protein Hrp1 in the regulation of elongation and termination by RNA polymerase II. Hrp1 is
structurally related to human hnRNP proteins in which inherited substitutions cause
neurodegenerative disorders, including ALS and FTLD. Furthermore, Hrp1 exhibits a similar
propensity to form intracellular aggregates, which are associated with pathology of the human
proteins. A more complete understanding of these fundamental processes should lead to more
accurate diagnosis and prognosis of diseases caused by alterations in nuclear RNA-binding
proteins, and may ultimately result in new therapeutic approaches. Furthermore, the proposed
studies will illuminate basic mechanisms of eukaryotic gene expression that can be exploited for
synthetic biology and biotechnology.

Grant Number: 5R35GM118075-10
NIH Institute/Center: NIH
Principal Investigator: DAVID BROW