High-Throughput Characterization of Viral and Cellular Protein Expression Patterns During JC Polyomavirus Infection

Armstrong

et al. 2020

J Virol

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Animal models are crucial in advancing biomedical research and defining the pathogenesis of human disease. Unfortunately, not all diseases can be easily modeled in a nonhuman host or such models are cost prohibitive to generate, including models for the human-specific virus JC polyomavirus (JCPyV). JCPyV infects most of the population but can cause a rare, fatal disease, progressive multifocal leukoencephalopathy (PML). There have been considerable advancements in understanding the molecular mechanisms of JCPyV infection, but this has mostly been limited to immortalized cell culture models. In contrast, PML pathogenesis research has been greatly hindered because of the lack of an animal model. We have further characterized JCPyV infection in primary human astrocytes to better define the infectious process in a primary cell type. Albeit a cell culture model, primary astrocytes may better recapitulate human disease, are easier to maintain than other primary cells, and are less expensive than using an animal model.

Section: Methodsmentioning

confidence: 99%

JC Polyomavirus Infection Reveals Delayed Progression of the Infectious Cycle in Normal Human Astrocytes

Wilczek

Armstrong

et al. 2020

J Virol

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“…An essential part of host-cell dysregulation during viral infection occurs through the manipulation of cellular signaling mechanisms, the cascades that facilitate intracellular and extracellular communication. JCPyV activates the extracellular-signal regulated kinase (ERK) component of the mitogen-activated protein kinase (MAPK-ERK) cascade upon infection, which is required for viral transcription and infection [18,23,24,25]. MAPK-ERK functions to transmit external mitogenic signals inward, to generate the appropriate cellular responses such as: cellular growth, differentiation, or cellular survival [26,27].…”

Section: Introductionmentioning

confidence: 99%

JCPyV-Induced MAPK Signaling Activates Transcription Factors during Infection

Mayberry

Wilczek

et al. 2019

IJMS

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JC polyomavirus (JCPyV), a ubiquitous human pathogen, is the etiological agent of the fatal neurodegenerative disease progressive multifocal leukoencephalopathy (PML). Like most viruses, JCPyV infection requires the activation of host-cell signaling pathways in order to promote viral replication processes. Previous works have established the necessity of the extracellular signal-regulated kinase (ERK), the terminal core kinase of the mitogen-activated protein kinase (MAPK) cascade (MAPK-ERK) for facilitating transcription of the JCPyV genome. However, the underlying mechanisms by which the MAPK-ERK pathway becomes activated and induces viral transcription are poorly understood. Treatment of cells with siRNAs specific for Raf and MAP kinase kinase (MEK) targets proteins in the MAPK-ERK cascade, significantly reducing JCPyV infection. MEK, the dual-specificity kinase responsible for the phosphorylation of ERK, is phosphorylated at times congruent with early events in the virus infectious cycle. Moreover, a MAPK-specific signaling array revealed that transcription factors downstream of the MAPK cascade, including cMyc and SMAD4, are upregulated within infected cells. Confocal microscopy analysis demonstrated that cMyc and SMAD4 shuttle to the nucleus during infection, and nuclear localization is reduced when ERK is inhibited. These findings suggest that JCPyV induction of the MAPK-ERK pathway is mediated by Raf and MEK and leads to the activation of downstream transcription factors during infection. This study further defines the role of the MAPK cascade during JCPyV infection and the downstream signaling consequences, illuminating kinases as potential therapeutic targets for viral infection.

“…In addition to these inhibitors, the use of siRNAs to target Raf, ERK, or other components of the MAPK signaling pathway have provided added experimental advantages [4,13]. In addition to cell-based infectivity assays, biochemical assays to measure phosphorylation of the kinases within the MAPK cascade have been carried out using Western blotting or In-cell Western (ICW) TM technologies [16]. Together, advances in experimental technologies have significantly increased our understanding of the MAPK pathway during the viral infectious cycle.…”

Section: Mapk-erk Cascadementioning

confidence: 99%

“…Multiple reports have indicated that MAPK-ERK activation during JCPyV challenge is required for successful infection in multiple cell types [75,76,78]. Chemical inhibition of MAPK-ERK proteins, including Raf (Bay43-9006) and MEK (PD98059, U0126), results in significant reductions in JCPyV infectivity [16,75,76,78]. This inhibition of ERK activity may play a direct role in preventing ERK nuclear localization and subsequent activation of the requisite transcription factors needed to facilitate viral replication.…”

Section: Dna Virusesmentioning

confidence: 99%

Human DNA Virus Exploitation of the MAPK-ERK Cascade

Maginnis

2019

IJMS

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The extracellular signal-regulated kinases (ERKs) comprise a particular branch of the mitogen-activated protein kinase cascades (MAPK) that transmits extracellular signals into the intracellular environment to trigger cellular growth responses. Similar to other MAPK cascades, the MAPK-ERK pathway signals through three core kinases—Raf, MAPK/ERK kinase (MEK), and ERK—which drive the signaling mechanisms responsible for the induction of cellular responses from extracellular stimuli including differentiation, proliferation, and cellular survival. However, pathogens like DNA viruses alter MAPK-ERK signaling in order to access DNA replication machineries, induce a proliferative state in the cell, or even prevent cell death mechanisms in response to pathogen recognition. Differential utilization of this pathway by multiple DNA viruses highlights the dynamic nature of the MAPK-ERK pathway within the cell and the importance of its function in regulating a wide variety of cellular fates that ultimately influence viral infection and, in some cases, result in tumorigenesis.