Weitzman Lab

[hide] I work on HSV-1 which is a really interesting virus because its large number of open reading frames allow it to interact with and exploit the host cell on many different levels. HSV-1 replicates in epithelial cells and from there it is transported to the cell bodies of the neurons innervating the site of infection. Once in the neurons, the virus can establish a latent state that lasts for the lifetime of the host. The virus periodically reactivates from latency to cause a new lesion at the site of the initial infection. I have found that HSV-1 can induce a DNA damage response and exploit the host cell’s DNA repair machinery to aid its own replication in non-neuronal cells. However, this response to HSV infection appears to be abrogated in neurons. I am really interested in the possibility that it is this lack of DNA damage response in neurons that forces the virus into latency. In a related project, I work on one of the first viral proteins to be expressed during an HSV-1 infection. This protein, ICP0, is an E3 ubiquitin ligase which degrades several cellular proteins to create an environment which is optimal for viral replication. I am interested in the ways in which ICP0 creates this environment and I have discovered a new function for ICP0 in which it ensures that the cellular DNA repair proteins are available to be pulled into the viral replication centers. I worked on HSV-1 in my previous lab and have maintained a strong interest in this virus but in the Weitzman lab I have also had the opportunity to work on several other viral systems. I identified a role for APOBEC3A, a cellular deaminase which blocks AAV replication and I have also been involved in an Adenovirus project and a phage/AAV hybrid vector gene therapy project. The great thing about working with viruses is that you get to work on a wide range of topics; you basically get to go wherever your viruses take you!

[hide] During my PhD studies, I have mostly been interested in the characterization and regulation of natural antisense transcripts in human retroviruses. These studies have allowed to highlight the existence of antisense transcription in several retroviruses, including HIV-1 and HTLV-1. Interestingly, HTLV-1 antisense transcript has been shown to allow the expression of a new viral protein, the HTLV-1 bZIP factor (HBZ), which is now thought to play an important role in the development of HTLV-1-associated diseases. My current interests are focused on the newly described antiviral activity of APOBEC3A.

[hide] I am interested in the chemistry and enzymology of DNA damage and repair, and the way in which organisms strike a balance between these two opposing processes to maintain their fitness, fuel their evolution, and defend themselves against pathogens. My initial work here in the Weitzman lab will focus on analyzing the mechanism(s) by which the cytidine deaminase APOBEC3A provides a prophylactic affect against adeno-associated virus.

[hide] In my previous lab, I studied the nuclear environment during EBV lytic infection. In order to characterize lytic replication of EBV in the absence of any other external stimuli, I established a Tet inducible system for expressing BZLF1 protein in the B95-8 cell line, which is latently infected with EBV. Using this system, I have shown that EBV lytic infection mimics the S phase of the cell cycle based on hyperphsophorylation of RB and CDK activity; however, host DNA replication is inhibited. EBV replicative intermediate structures contain TUNEL positive DNA breaks, which attract homologous recombinational repair factors and elicit a cellular ATM-mediated DNA damage response. Additionally, host DNA replicative helicases are phsophorylated by redundant actions of CDK and EBV-PK during EBV lytic infection thus preventing host DNA replication. Currently I am using proteomic approaches in the lab to identify new cellular substrates and components of viral ubiquitin ligase complexes.

[hide] My research in the lab is primarily focused on how cellular proteins are able to recognize and process the ends of the adenoviral genome. Since the 5’ ends of the adenoviral genome are protected by a covalently bound, virally encoded terminal protein, my current research is to understand which cellular proteins possess the enzymatic ability to remove this protein. I am employing molecular biology and setting up biochemical assays to understand this process. I have also previously contributed to projects in the lab understanding the adenoviral proteins E1b55K and E4orf3. These proteins can both sequester various cellular proteins to modify the cellular environment allowing for a productive viral infection. My work on E1b55K demonstrated its ability to sequester the potential cellular tumor suppressor SSBP2 into a cytoplasmic aggresome. My work on E4orf3 demonstrated that its ability to mislocalize and immobilize the MRN complex prevents the activation of an ATR dependent DNA damage response upon infection.

 

 

[hide] I am particularly interested in the virus-host interactions between the HSV-1 protein ICP0, an E3 ubiquitin ligase, and cellular proteins that may be degradation targets. I am using mass-spec based approaches to identify novel targets of ICP0.