David Peterson - US grants

This project seeks to understand the ways that cells maintain the fidelity of transcription, the first step in the utilization of genetic information. Transcription of protein-coding genes is catalyzed by RNA polymerase II (pol II), an enzyme that contains 12 different protein components in the model organism Saccharomyces cerevisiae (baker's yeast). Maintaining transcriptional fidelity is important, as even a small population of altered RNA transcripts could have very negative consequences for the cell, such as production of dominant negative proteins that could disrupt other cellular functions. Preliminary results have demonstrated that Rpb9, a small, non-essential subunit of pol II, is required for accurate transcription. The research is designed to answer the following questions: How does Rpb9 contribute to transcriptional fidelity? Is error-prone transcription an inherent property of Rpb9-deficient pol II? What other proteins affect transcriptional fidelity?

These questions will be addressed with three approaches. The first approach will examine the transcriptional properties of Rpb9-deficient pol II. Transcriptional activity will be examined in vitro to directly assess the rates of NTP misincorporation and extension after misincorporation, as well as the rate of nucleolytic proofreading of a misincorporated nucleotide. Potential effects of Rpb9 on the Km for incorporation of correct and incorrect nucleotides will also be explored. Preliminary studies have established that when Rpb9 is missing from pol II, the rate of misincorporation of UTP for a templated CTP is increased, and, furthermore, that the misincorporated U at the 3'-end of the nascent RNA is less likely to be excised by proofreading. A second experimental approach will identify amino acids or domains of Rpb9 that are important for maintaining fidelity. Mutations will be engineered at sites designed to disrupt function or alter interactions with other proteins, and an alternative, unbiased strategy will be exploited to generate random mutations in RPB9. Altered functions resulting from these mutations will be assessed both in vivo and in vitro. The third approach will identify other genes important for transcriptional fidelity based on synthetic lethality when they are deleted in the context of a deletion in RPB9 or by their ability to suppress mutations in RPB9. At least one gene, which encodes a subunit of the chromatin remodeling coactivator SAGA, has been shown in preliminary work to have an effect on transcriptional fidelity in vivo.

Broader Impacts: From a broader perspective, the proposed research will not only generate new knowledge, but it will also serve to train graduate and undergraduate students, including participants in an NSF-sponsored REU program. The research activities at large public universities are their most notable and under-utilized asset for providing learning experiences for students, and the PI has a long history of training undergraduate and high school students in his lab.

General Abstract
Election campaigns serve an extremely important role in our democracy. The messages sent to voters help to define what elections will be about and how voters will ultimately choose. Two new advertising technologies -- the use of large amounts of data about individual voters and new online advertising platforms such as YouTube -- have the potential to revolutionize how campaigns are able to craft specific messages to appeal to individual voters. To date, however, there is no systematic evidence about the accuracy or effectiveness of targeting via online video advertising. This project will be the first to test how effectively campaigns can target voters with online advertising. The PIs will develop new computer science tools to capture and code the content of online advertising. This will allow the PIs to test a series of hypotheses about the effectiveness of targeting, the strategies used in online advertising, and the abilities of the rival campaigns to respond to one another. The interdisciplinary team will make its tools and data freely available to the research community, train students in both political science and computer science, and create mechanisms for real time tracking of advertising, which will be shared with leading media outlets.

Technical Abstract
In this proposal, the PIs set devise an empirical study of the effectiveness of political campaigns to micro-target online advertising to audiences. They develop two sets of computational tools to test the effectiveness of online advertising micro-targeting. The first of tools are a set of 'bots' with manipulated profile characteristics that mimic different types of voters. These bots allow the team to track the advertisements shown to "voters" and test for differences based on the bots' profile characteristics. The team will rely on YouTube as the on-line platform for the study as it is very popular, and was utilized by candidates during the recent presidential election campaigns. YouTube boasts over 1 billion users, and over 4 billion video views a day. More than a million advertisers utilize the Google ad platform that provides advertisers ability to select target users based on factors such as gender, age, marital status, and interests that coincide with Google's categories of interest. Furthermore, the platform accepts ads delivered from third-party sites. To test hypotheses about the effectiveness of targeting, the team plan to develop a second set of tools that allow them to code automatically the online ads along multiple dimensions. This will allow them to construct real-time measures of the messages sent to voters and to assess multiple theories regarding the ability of campaigns to target voters via online advertising.