Biology subjects

Farrar, D.

Publications and source records attributed to Farrar, D..

3 recordsLinked to original sources

bioRxiv2025

Single-cell tracking of genetically minimized Salmonella reveals mechanisms of effector gene cooperation.

Bacterial pathogens encode secretory systems that deliver large repertoires of effector proteins directly into host cells. While many effector proteins have been characterized biochemically, it is unclear where and when they function within complex cellular systems of host tissues. This problem exists because of the extensive genetic and functional redundancies found in large effector protein repertoires. Here, we coupled targeted genome minimization with single cell mass cytometry to track the cellular location where Salmonella Typhimurium (S.Tm) SPI-2 Type Three Secretion System effector proteins function in a time-resolved animal model of infection. This approach revealed the temporal progression of S.Tm transmission within a complex tissue and pinpointed effector genes responsible for pathogen dissemination between host immune cell types. We further show how coupling two effector gene networks acquired during distinct episodes of bacterial evolution has shaped the cellular and tissue tropism of non-Typhoidal Salmonella species. Together, these results illustrate a top-down genetic approach to interrogate host-pathogen interactions hidden by functional redundancies within large virulence factor gene networks.

microbiology↗

bioRxiv2021

Adrenergic signaling controls early transcriptional programs during CD8+ T cell responses to viral infection

Viral infections drive the expansion and differentiation of responding CD8+ T cells into variegated populations of cytolytic effector and memory cells. While pro-inflammatory cytokines and cell surface immune receptors play a key role in guiding T cell responses to infection, T cells are also markedly influenced by neurotransmitters. Norepinephrine is a key sympathetic neurotransmitter, which acts to suppress CD8 + T cell cytokine secretion and lytic activity by signaling through the {beta}2-adrenergic receptor (ADRB2). Although ADRB2 signaling is considered generally immunosuppressive, its role in regulating differentiation of effector T cells in response to infection has not been investigated. Using an adoptive transfer approach, we compared the expansion and differentiation of wild type (WT) to Adrb2-/- CD8 + T cells throughout the primary response to vesicular stomatitis virus (VSV) infection in vivo. We measured the dynamic changes in transcriptome profiles of antigen-specific CD8 + T cells as they responded to VSV. Within the first 7 days of infection, WT cells out-paced the expansion of Adrb2-/- cells, which correlated with reduced expression of IL-2 and the IL-2R in the absence of ADRB2. RNASeq analysis identified over 300 differentially expressed genes that were both temporally regulated following infection and selectively regulated in WT vs Adrb2-/- cells. These genes contributed to major transcriptional pathways including cytokine receptor activation, signaling in cancer, immune deficiency, and neurotransmitter pathways. By parsing genes within groups that were either induced or repressed over time in response to infection, we identified three main branches of genes that were differentially regulated by the ADRB2. These gene sets were predicted to be regulated by specific transcription factors involved in effector T cell development, such as Tbx21 and Eomes. Collectively, these data demonstrate a significant role for ADRB2 signaling in regulating key transcriptional pathways during CD8 + T cells responses to infection that may dramatically impact their functional capabilities and downstream memory cell development.

immunology↗

bioRxiv2017

Activation of the Androgen Receptor gene by BORIS/CTCFL in prostate cancer cells

BORIS/CTCFL, a paralogue of the chromatin architectural protein CTCF, is a member of the cancer-testis antigen family, normally present in the testes. BORIS is expressed in various tumours, including prostate cancers, however the function of BORIS in cancer cells is not well defined. The androgen receptor (AR) plays a critical role in the normal development of a human prostate gland and pathogenesis of prostate cancer. In our previous study we described a positive correlation between elevated levels of BORIS and AR in prostate cancers, and activation of the AR gene by BORIS in prostate cancer cells. Elucidation of the mechanisms involved in the modulation of AR activity is important to understand prostate tumourigenesis and investigation of transcriptional regulation of the AR gene by BORIS may provide new insights into this issue. Here we report the ability of BORIS to not only positively regulate AR in androgen-dependent prostate cancer (ADPC) cells, but re-activate epigenetically silenced AR in androgen-independent prostate cancer (AIPC) cells leading to the production of biologically active AR protein. CTCF, on the other hand, had repressive effects on the AR. In both, ADPC and AIPC cells, introduction of ectopic BORIS was associated with the reduction in the AR promoter methylation, increase in active and decrease in repressive chromatin marks, and decrease in CTCF occupancies at the two main upstream BORIS/CTCF binding sites. We propose a model of epigenetic regulation of AR by BORIS in prostate cells whereby BORIS remodels the chromatin at the AR promoter leading to transcriptional activation.

cancer biology↗