Biology subjects

Carter, C. C.

Publications and source records attributed to Carter, C. C..

3 recordsLinked to original sources

bioRxiv2024

Evolution of intrinsic transcriptional terminators in their genomic context

Transcriptional gene expression relies on two fundamental processes - transcription initiation and termination. Transcriptional termination is essential for the coordinated control of gene expression. Intrinsic termination, the major mechanism of transcriptional termination in bacteria, relies on the sequence-dependent folding of nascent mRNA into a hairpin structure that enables RNA polymerase to dissociate from DNA. Despite their central role in regulating expression in prokaryotic genomes, the conservation of intrinsic terminators and the factors that shape their evolution remain poorly understood. Here, we combine comparative genomics with experimental measurements of terminator function, to study the conservation of intrinsic terminators between Escherichia coli and Salmonella enterica subsp. pullorum. While the two species are closely related, the sequence and function of most terminators are not conserved, with less than 20% of all terminators having an identifiable ortholog - in stark contrast to 60% for coding sequences. Terminators with higher sequence conservation also had more conserved function, indicative of stabilizing selection. The local genomic context shapes the evolution of intrinsic terminators, as their sequence conservation is dependent on the conservation of the upstream gene, while their function is affected by the distance to the downstream gene. Ultimately, any theory of gene regulatory network evolution ought to account for how transcriptional terminators evolve.

evolutionary biology↗

bioRxiv2020

Dengue activates mTORC2 signaling to counteract apoptosis and maximize viral replication

The mechanistic target of rapamycin (mTOR) functions in at least two distinct complexes: mTORC1, which regulates cellular anabolic-catabolic homeostasis, and mTORC2, which is an important regulator of cell survival and cytoskeletal maintenance. mTORC1 has been implicated in the pathogenesis of flaviviruses including dengue, where it contributes to the establishment of a pro-viral autophagic state. In contrast, the role of mTORC2 in viral pathogenesis is unknown. In this study, we explore the consequences of a physical protein-protein interaction between dengue non-structural protein 5 (NS5) and host cell mTOR proteins during infection. Using shRNA to differentially target mTORC1 and mTORC2 complexes, we show that mTORC2 is required for optimal dengue replication. Furthermore, we show that mTORC2 is activated during viral replication, and that mTORC2 counteracts virus-induced apoptosis, promoting the survival of infected cells. This work reveals a novel mechanism by which the dengue flavivirus can promote cell survival to maximize viral replication.

microbiology↗

bioRxiv2018

Maternal immune activation causes age-specific changes in cytokine receptor expression in offspring throughout development

Maternal infection is a shared environmental risk factor for a spectrum of neuropsychiatric disorders and animal models of maternal immune activation (MIA) exhibit a range of neuropathologies and behaviors with relevance to these disorders. In particular, MIA offspring show chronic, age- and region-dependent changes in brain cytokines, a feature seen in postmortem studies of individuals with neuropsychiatric disorders. These MIA-induced alterations in brain cytokines may index biological processes underlying progression to diagnosable neuropsychiatric disorders. However, cytokines signal through specific cytokine receptors to alter cellular processes and it is the levels of those receptors that are critical for signaling. Yet, it remains unknown whether MIA alters the expression of cytokine receptors in the brains of offspring throughout postnatal development. Here, we measured the expression of 23 cytokine receptors in the frontal cortex of MIA and control offspring from birth to adulthood using qPCR. MIA offspring show dynamic oscillating alterations in cytokine receptors during sensitive periods of neural growth and synaptogenesis. Of the many cytokine receptors altered in the FC of MIA offspring, five were significantly changed at multiple ages at levels over 2-fold relative to controls--Il1r1, Ifngr1, Il10ra, Cx3cr1 and Gmcsfr--suggesting persistent dysfunction within those pathways. In addition to facilitating immune responses, these cytokine receptors play critical roles in neuronal migration and maturation, synapse formation and elimination, and microglial function. Together with previously reported changes in cytokine levels in the brains of MIA offspring, our results show a decrease in cytokine signaling during the peak period of synaptogenesis and spine formation and an increase during periods of activity-dependent development and early adulthood. Overall, the oscillating, age-dependent cytokine receptor alterations in the FC of MIA offspring identified here may have diagnostic and therapeutic value for neuropsychiatric disorders with a neuro-immune etiology.\n\nResearch HighlightMaternal immune activation leads to long-lasting, oscillating changes in cytokine receptors in the frontal cortex of offspring throughout development.

neuroscience↗