Biology subjects

Collins-McMillen, D.

Publications and source records attributed to Collins-McMillen, D..

3 recordsLinked to original sources

bioRxiv2023

Human Cytomegalovirus UL138 Interaction with USP1 Activates STAT1 in infection

Innate immune responses are crucial for limiting virus infection. However, viruses often hijack our best defenses for viral objectives. Human Cytomegalovirus (HCMV) is a beta herpesvirus which establishes a life-long latent infection. Defining the virus-host interactions controlling latency and reactivation is vital to the control of viral disease risk posed by virus reactivation. We defined an interaction between UL138, a pro-latency HCMV gene, and the host deubiquintase complex, UAF1-USP1. UAF1 is a scaffold protein pivotal for the activity of ubiquitin specific peptidases (USP), including USP1. UAF1-USP1 sustains an innate immune response through the phosphorylation and activation of signal transducer and activator of transcription-1 (pSTAT1), as well as regulates the DNA damage response. After the onset of viral DNA synthesis, pSTAT1 levels are elevated and this depends upon UL138 and USP1. pSTAT1 localizes to viral centers of replication, binds to the viral genome, and influences UL138 expression. Inhibition of USP1 results in a failure to establish latency, marked by increased viral genome replication and production of viral progeny. Inhibition of Jak-STAT signaling also results in increased viral genome synthesis in hematopoietic cells, consistent with a role for USP1-mediated regulation of STAT1 signaling in the establishment of latency. These findings demonstrate the importance of the UL138-UAF1-USP1 virus-host interaction in regulating HCMV latency establishment through the control of innate immune signaling. It will be important going forward to distinguish roles of UAF1-USP1 in regulating pSTAT1 relative to its role in the DNA damage response in HCMV infection. ImportanceHuman cytomegalovirus (HCMV) is one of nine herpesviruses that infect humans. Following a primary infection, HCMV establishes a life-long latent infection that is marked by sporadic, and likely frequent reactivation events. While these reactivation events are asymptomatic in the immune competent host, they pose important disease risks for the immune compromised, including solid organ or stem cell transplant recipients. Its complex interactions with host biology and deep coding capacity make it an excellent model for defining mechanisms important for viral latency and reactivation. Here we define an interaction with host proteins that commandeer typically antiviral innate immune signaling for the establishment of latency.

microbiology↗

bioRxiv2020

FOXO Transcription Factors Activate Alternative Major Immediate Early Promoters to Induce Human Cytomegalovirus Reactivation

A key step during viral reactivation from latency is the re-expression of viral genes. Hematopoietic progenitor cells (HPCs) support human cytomegalovirus (HCMV) latency, and their differentiation triggers cellular cues that drive reactivation. A key step during HCMV reactivation in latently infected HPCs is re-expression of viral genes. We recently determined that the major immediate early promoter (MIEP), which is primarily responsible for MIE gene expression during lytic replication, remains silent during reactivation. Instead, alternative promoters in the MIE locus are induced by reactivation stimuli. Here, we find that forkhead family (FOXO) transcription factors are critical for activation of alternative MIE promoters during HCMV reactivation, as mutating FOXO binding sites in alternative MIE promoters decreased HCMV IE gene expression upon reactivation and significantly decreased the production of infectious virus from latently infected primary CD34+ HPCs. These findings establish a mechanistic link by which infected cells sense environmental cues to regulate latency and reactivation, and emphasize the role of contextual activation of alternative MIE promoters as the primary drivers of reactivation. SignificanceHuman cytomegalovirus infection is lifelong and persistent. Periodic reactivation of cytomegalovirus poses serious disease risk for immune-compromised patients. A critical driver of reactivation is expression of viral genes from the major immediate early locus. Recent paradigm-shifting evidence shows that reactivation is driven from promoters distinct from those that drive replication in permissive cells. Understanding the contextual control of these promoters and how they specifically respond to cellular cues that drive reactivation is critical for establishing future therapies that prevent reactivation. Our findings mechanistically define a previously enigmatic relationship between differentiation and reactivation, and provide potential targets for therapeutic intervention to prevent HCMV reactivation and disease.

microbiology↗

bioRxiv2018

Alternative Promoters Drive Human Cytomegalovirus Reactivation from Latency

Reactivation from latency requires reinitiation of viral gene expression and culminates in the production of infectious progeny. The major immediate early promoter (MIEP) of human cytomegalovirus (HCMV) drives the expression of crucial lytic cycle transactivators but is silenced during latency in hematopoietic progenitor cells (HPCs). Because the MIEP is poorly active in HPCs, it is unclear how viral transactivators are expressed during reactivation. We demonstrate that transcripts originating from alternative promoters within the canonical major immediate early locus are abundantly expressed upon reactivation, whereas MIEP-derived transcripts remain undetectable. Further, we show that these promoters are necessary for efficient reactivation in primary CD34+ HPCs. Our findings change the paradigm for HCMV reactivation by demonstrating that promoter switching governs reactivation from viral latency in a context-specific manner.

microbiology↗