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Thesis
Peer Reviewed

Battling Drug Resistance: A Tale of Two Pathogens

UC San Diego Electronic Theses and Dissertations (2016)

HIV/AIDS, malaria, and tuberculosis are the world’s three deadliest infectious diseases of humans, often referred to as the ‘Big Three’. Together, they are responsible for more than 10% of all the deaths worldwide each year. What is perhaps most worrisome is the fact that the current therapies that treat

these conditions are losing their efficacy due to the emergence of antimicrobial drug resistance. Accordingly, research is urgently needed to address the growing problem of drug resistance and to help drive the development of novel therapeutics. In the first chapter of this doctoral dissertation, three strategies to combat drug resistance are discussed: 1. Developing therapeutics that target host-derived factors, 2. Identifying new antimicrobial inhibitors, and 3. Investigating host-pathogen biology using systems analysis to drive the development of novel therapeutics. Examples of research utilizing these strategies are discussed in the following chapters, with a particular focus on two of the “Big Three” pathogens- HIV-1 and the malaria parasite, Plasmodium. The identification and characterization of a novel host factor that regulates HIV-1 reverse transcription is described in Chapter 2. In Chapter 3, the development of a high-throughput phenotypic assay to identify novel antimalarial drugs is discussed, and in Chapter 4, a broad review of systems biology-based research of host-parasite interactions (with an emphasis on Plasmodium) is included. The Appendix includes preliminary data and future aims for systems biology research aimed at understanding Plasmodium liver-stage development. Through the combination of these scientific efforts, we will surely strength our position in the ongoing battle against antimicrobial drug resistance.

5 supplemental files

Cover page: Battling Drug Resistance: A Tale of Two Pathogens

Article
Peer Reviewed

RNA-binding protein CPEB1 remodels host and viral RNA landscapes

UC Santa Cruz Previously Published Works (2016)

Host and virus interactions occurring at the post-transcriptional level are critical for infection but remain poorly understood. Here, we performed comprehensive transcriptome-wide analyses revealing that human cytomegalovirus (HCMV) infection results in widespread alternative splicing (AS), shortening of 3' untranslated regions (3' UTRs) and lengthening of poly(A)-tails in host gene transcripts. We found that the host RNA-binding protein CPEB1 was highly induced after infection, and ectopic expression of CPEB1 in noninfected cells recapitulated infection-related post-transcriptional changes. CPEB1 was also required for poly(A)-tail lengthening of viral RNAs important for productive infection. Strikingly, depletion of CPEB1 reversed infection-related cytopathology and post-transcriptional changes, and decreased productive HCMV titers. Host RNA processing was also altered in herpes simplex virus-2 (HSV-2)-infected cells, thereby indicating that this phenomenon might be a common occurrence during herpesvirus infections. We anticipate that our work may serve as a starting point for therapeutic targeting of host RNA-binding proteins in herpesvirus infections.

Cover page: RNA-binding protein CPEB1 remodels host and viral RNA landscapes

Article
Peer Reviewed

SREBP2-dependent lipid gene transcription enhances the infection of human dendritic cells by Zika virus

UC San Diego Previously Published Works (2022)

The emergence of Zika virus (ZIKV) as a global health threat has highlighted the unmet need for ZIKV-specific vaccines and antiviral treatments. ZIKV infects dendritic cells (DC), which have pivotal functions in activating innate and adaptive antiviral responses; however, the mechanisms by which DC function is subverted to establish ZIKV infection are unclear. Here we develop a genomics profiling method that enables discrete analysis of ZIKV-infected versus neighboring, uninfected primary human DCs to increase the sensitivity and specificity with which ZIKV-modulated pathways can be identified. The results show that ZIKV infection specifically increases the expression of genes enriched for lipid metabolism-related functions. ZIKV infection also increases the recruitment of sterol regulatory element-binding protein (SREBP) transcription factors to lipid gene promoters, while pharmacologic inhibition or genetic silencing of SREBP2 suppresses ZIKV infection of DCs. Our data thus identify SREBP2-activated transcription as a mechanism for promoting ZIKV infection amenable to therapeutic targeting.

Cover page: SREBP2-dependent lipid gene transcription enhances the infection of human dendritic cells by Zika virus

Article
Peer Reviewed

25-Hydroxycholesterol activates the integrated stress response to reprogram transcription and translation in macrophages.

UC San Diego Previously Published Works (2013)

25-Hydroxycholesterol (25OHC) is an enzymatically derived oxidation product of cholesterol that modulates lipid metabolism and immunity. 25OHC is synthesized in response to interferons and exerts broad antiviral activity by as yet poorly characterized mechanisms. To gain further insights into the basis for antiviral activity, we evaluated time-dependent responses of the macrophage lipidome and transcriptome to 25OHC treatment. In addition to altering specific aspects of cholesterol and sphingolipid metabolism, we found that 25OHC activates integrated stress response (ISR) genes and reprograms protein translation. Effects of 25OHC on ISR gene expression were independent of liver X receptors and sterol-response element-binding proteins and instead primarily resulted from activation of the GCN2/eIF2α/ATF4 branch of the ISR pathway. These studies reveal that 25OHC activates the integrated stress response, which may contribute to its antiviral activity.

Article
Peer Reviewed

25-Hydroxycholesterol Activates the Integrated Stress Response to Reprogram Transcription and Translation in Macrophages*

UC San Diego Previously Published Works (2013)

25-Hydroxycholesterol (25OHC) is an enzymatically derived oxidation product of cholesterol that modulates lipid metabolism and immunity. 25OHC is synthesized in response to interferons and exerts broad antiviral activity by as yet poorly characterized mechanisms. To gain further insights into the basis for antiviral activity, we evaluated time-dependent responses of the macrophage lipidome and transcriptome to 25OHC treatment. In addition to altering specific aspects of cholesterol and sphingolipid metabolism, we found that 25OHC activates integrated stress response (ISR) genes and reprograms protein translation. Effects of 25OHC on ISR gene expression were independent of liver X receptors and sterol-response element-binding proteins and instead primarily resulted from activation of the GCN2/eIF2α/ATF4 branch of the ISR pathway. These studies reveal that 25OHC activates the integrated stress response, which may contribute to its antiviral activity.