Biology subjects

Bowen, J. R.

Publications and source records attributed to Bowen, J. R..

3 recordsLinked to original sources

bioRxiv2019

STAT5: A Target of Antagonism by Neurotropic Flaviviruses

Flaviviruses are a diverse group of arthropod-borne viruses responsible for numerous significant public health threats; therefore, understanding the interactions between these viruses and the human immune response remains vital. Earlier work has found that WNV and ZIKV infect human DCs and can block antiviral immune responses in DCs. Previously, we used mRNA sequencing and weighted gene co-expression network analysis (WGCNA) to define molecular signatures of antiviral DC responses following activation of innate immune signaling (RIG-I, MDA5, or type I IFN signaling) or infection with WNV. Using this approach, we found that several genes involved in T cell co-signaling and antigen processing were not enriched in DCs during WNV infection. Using cis-regulatory sequence analysis, STAT5 was identified as a regulator of DC activation and immune responses downstream of innate immune signaling that was not activated during either WNV or ZIKV infection. Mechanistically, WNV and ZIKV actively blocked STAT5 phosphorylation downstream of RIG-I, IFN{beta}, and IL-4, but not GM-CSF signaling. Unexpectedly, dengue virus serotypes 1-4 (DENV1-4) and the yellow fever 17D vaccine strain (YFV-17D) did not antagonize STAT5 phosphorylation. In contrast to WNV, ZIKV inhibited JAK1 and TYK2 phosphorylation following type I IFN treatment, suggesting divergent mechanisms used by these viruses to inhibit STAT5 activation. Combined, these findings identify STAT5 as a target of antagonism by specific pathogenic flaviviruses to subvert the immune response in infected DCs.\n\nImportanceFlaviviruses are a diverse group of insect-borne viruses responsible for numerous significant public health threats. Previously, we used a computational biology approach to define molecular signatures of antiviral DC responses following activation of innate immune signaling or infection with WNV. In this work, we identify STAT5 as a regulator of DC activation and antiviral immune responses downstream of innate immune signaling that was not activated during either WNV or ZIKV infection. WNV and ZIKV actively blocked STAT5 phosphorylation downstream of RIG-I, IFN{beta}, and IL-4, but not GM-CSF signaling. However, other related flaviviruses, dengue virus serotypes 1-4 and yellow fever 17D vaccine strain, did not antagonize STAT5 phosphorylation. Mechanistically, WNV and ZIKV showed differential inhibition of Jak kinases upstream of STAT5, suggesting divergent countermeasures to inhibit STAT5 activation. Combined, these findings identify STAT5 as a target of antagonism by specific pathogenic flaviviruses to subvert antiviral immune responses in human DCs.

microbiology↗

bioRxiv2019

West Nile Virus Subverts T Cell Stimulatory Capacity of Human Dendritic Cells

West Nile virus (WNV) is a neurotropic flavivirus and the leading cause of mosquito-borne encephalitis in the United States. Recent studies in humans have found that dysfunctional T cell responses strongly correlate with development of severe WNV neuroinvasive disease. However, the contributions of human dendritic cells (DCs) in priming WNV-specific T cell immunity remains poorly understood. Here, we demonstrate that human monocyte-derived DCs (moDCs) support productive viral replication following infection with a pathogenic strain of WNV. Antiviral effector gene transcription was strongly induced during the log-phase viral growth, while secretion of type I interferons (IFN) occurred with delayed kinetics. Activation of RIG-I like receptor (RLR) or type I IFN signaling prior to log-phase viral growth significantly diminished viral replication, suggesting that activation of antiviral programs early can block WNV infection. In contrast to the induction of antiviral responses, WNV infection did not promote transcription or secretion of pro-inflammatory (IL-6, GM-CSF, CCL3, CCL5, CXCL9) or T cell modulatory cytokines (IL-4, IL-12, IL-15). There was also minimal induction of molecules associated with antigen presentation and T cell priming, including the co-stimulatory molecules CD80, CD86, and CD40. Functionally, WNV-infected moDCs dampened allogenic CD4 and CD8 T cell activation and proliferation. Combined, we propose a model where WNV subverts human DC activation to compromise priming of WNV-specific T cell immunity.\n\nImportanceWest Nile virus (WNV) is an encephalitic flavivirus that remains endemic in the United States. Previous studies have found dysfunctional T cell responses correlate to severe disease outcomes during human WNV infection. Here, we sought to better understand the ability of WNV to program human dendritic cells (DCs) to prime WNV-specific T cell responses. While productive infection of monocyte-derived DCs activated antiviral and type I interferon responses, molecules associated with inflammation and programming of T cells were minimally induced. Functionally, WNV-infected DCs dampened T cell activation and proliferation during an allogeneic response. Combined, our data supports a model where WNV infection of human DCs compromises WNV-specific T cell immunity.

microbiology↗

bioRxiv2019

Proteomic profiling of the oncogenic septin 9 reveals isoform-specific interactions in breast cancer cells

Septins are a family of multimeric GTP-binding proteins, which are abnormally expressed in cancer. Septin 9 (SEPT9) is an essential and ubiquitously expressed septin with multiple isoforms, which have differential expression patterns and effects in breast cancer cells. It is unknown, however, if SEPT9 isoforms associate with different molecular networks and functions. Here, we performed a proteomic screen in MCF-7 breast cancer cells to identify the interactome of GFP-SEPT9 isoforms 1, 4 and 5, which vary significantly in their N-terminal extensions. While all three isoforms associated with SEPT2 and SEPT7, the truncated SEPT9_i4 and SEPT9_i5 interacted with septins of the SEPT6 group more promiscuously than SEPT9_i1, which bound predominately SEPT8. Spatial mapping and functional clustering of non-septin partners showed isoform-specific differences in interactions with proteins of distinct subcellular organelles (e.g., nuclei, centrosomes, cilia) and functions such as cell signaling and ubiquitination. Notably, the interactome of the full length SEPT9_i1 was more enriched in cytoskeletal regulators, while the truncated SEPT9_i4 and SEPT9_i5 exhibited preferential and isoform-specific interactions with nuclear, signaling and ubiquitinating proteins. These data provide evidence for isoform-specific interactions, which arise from truncations in the N-terminal extensions of SEPT9, and point to novel roles in the pathogenesis of breast cancer.

cell biology↗