Biology subjects

Dolan, P. T.

Publications and source records attributed to Dolan, P. T..

8 recordsLinked to original sources

bioRxiv2025

Strain-Specific Tropism and Transcriptional Responses of Enterovirus D68 Infection in Human Spinal Cord Organoids

The mechanisms by which Enterovirus D-68 (EV-D68) infection leads to acute flaccid myelitis (AFM), a severe neurological condition characterized by sudden muscle weakness and paralysis, remain poorly understood. To investigate the cellular tropism and infection dynamics of EV-D68, we profiled naive and EV-D68-infected human spinal cord organoids (hSCOs) derived from induced pluripotent stem cells (iPSCs) using single-cell RNA sequencing (scRNA-seq). Examining the cellular composition of healthy hSCOs, we found that hSCOs comprise diverse cell types, including neurons, astrocytes, oligodendrocyte progenitor cells (OPCs), and multipotent glial progenitor cells (mGPCs). Upon infection with two EV-D68 strains, US/IL/14-18952 (a B2 strain) and US/MA/18-23089 (a B3 strain), we observed distinct viral tropism and host transcriptional responses. Notably, US/IL/14-18952 showed a significant preference for neurons, while US/MA/18-23089 exhibited higher rates of infection in cycling astrocytes and OPCs. These findings provide novel insights into the host cell tropism of EV-D68 in the spinal cord, offering insight into the potential mechanisms underlying AFM pathogenesis. Understanding the dynamics of infection at single-cell resolution will inform future therapeutic strategies aimed at mitigating the neurological impact of enteroviral infections.

microbiology↗

bioRxiv2024

Activating FcγRs on monocytes are necessary for optimal Mayaro virus clearance

Mayaro virus (MAYV) is an emerging arbovirus. Previous studies have shown antibody Fc effector functions are critical for optimal monoclonal antibody-mediated protection against alphaviruses; however, the requirement of Fc gamma receptors (Fc{gamma}Rs) for protection during natural infection has not been evaluated. Here, we showed mice lacking activating Fc{gamma}Rs (FcR{gamma}-/-) developed prolonged clinical disease with more virus in joint-associated tissues. Viral clearance was associated with anti-MAYV cell surface binding rather than neutralizing antibodies. Lack of Fc-Fc{gamma}R engagement increased the number of monocytes through chronic timepoints. Single cell RNA sequencing showed elevated levels of pro-inflammatory monocytes in joint-associated tissue with increased MAYV RNA present in FcR{gamma}-/- monocytes and macrophages. Transfer of FcR{gamma}-/- monocytes into wild type animals was sufficient to increase virus in joint-associated tissue. Overall, this study suggests that engagement of antibody Fc with activating Fc{gamma}Rs promotes protective responses during MAYV infection and prevents monocytes from being potential targets of infection.

immunology↗

bioRxiv2023

C1q Enables Influenza HA Stem Binding Antibodies to Block Viral Attachment and Broadens the Antibody Escape Repertoire

Broadly neutralizing, anti-hemagglutinin stem antibodies (Abs) are a promising universal influenza vaccine target. While anti-stem Abs are not believed to block viral attachment, we show that C1q confers attachment inhibition and boosts fusion and neuraminidase inhibition, greatly enhancing virus neutralization activity in vitro and in mice challenged with influenza virus via the respiratory route. These effects reflect increased steric interference and not increased Ab avidity. Remarkably, C1q greatly expands the anti-stem Ab viral escape repertoire to include residues throughout the hemagglutinin. Some substitutions cause antigenic alterations in the globular region or modulate HA receptor avidity. We also show that C1q enhances the neutralization activity of non-RBD anti-SARS-CoV-2 Spike Abs, an effect dependent on Spike density on the virion surface. Together, our findings show that first, Ab function must be considered in a physiological context and second, inferring the exact selection pressure for Ab-driven viral evolution is risky business, at best.

microbiology↗

bioRxiv2022

An ESCRT-dependent pathway of Nuclear and Cytoplasmic Spatial PQC is coordinated at Nuclear Vacuolar Junctions

Effective Protein Quality Control (PQC), essential for cellular health, relies on spatial sequestration of misfolded proteins into defined inclusions. Here we elucidate the coordination of nuclear and cytoplasmic spatial PQC. While cytoplasmic misfolded proteins concentrate in a cytoplasmic, perinuclear Juxta Nuclear Quality control compartment (JUNQ), nuclear misfolded proteins sequester into a perinucleolar IntraNuclear Quality control compartment (INQ). Particle tracking reveals the INQ and JUNQ converge to face each other across the nuclear envelope at a site proximal to the Nuclear-Vacuolar Junction (NVJ) marked by perinuclear ESCRT-II/-III protein Chm7. Strikingly, this ESCRT-dependent convergence facilitates VPS4-dependent vacuolar clearance of misfolded cytoplasmic and nuclear proteins, the latter entailing extrusion of nuclear INQ into the vacuole. We propose perinuclear ESCRT coordinates spatial PQC at nuclear-vacuolar contacts to facilitate vacuolar clearance of nuclear and cytoplasmic misfolded proteins.

biochemistry↗

bioRxiv2020

Differentiation drives widespread rewiring of the neural stem cell chaperone network

Neural stem and progenitor cells (NSPCs) are critical for continued cellular replacement in the adult brain. Life-long maintenance of a functional NSPC pool necessitates stringent mechanisms to preserve a pristine proteome. We find that the NSPCs chaperone network robustly maintains misfolded protein solubility and stress resilience through high levels of the ATP-dependent chaperonin TRiC/CCT. Strikingly, NSPC differentiation rewires the cellular chaperone network, reducing TRiC/CCT levels and inducing those of the ATP-independent small heat shock proteins (sHSPs). This switches the proteostasis strategy in neural progeny cells to promote sequestration of misfolded proteins into protective inclusions. The chaperone network of NSPCs is more effective than that of differentiated cells, leading to improved management of proteotoxic stress and amyloidogenic proteins. However, NSPC proteostasis is impaired by brain aging. The less efficient chaperone network of differentiated neural progeny may contribute to their enhanced susceptibility to neurodegenerative diseases characterized by aberrant protein misfolding and aggregation.

molecular biology↗

bioRxiv2020

Principles of dengue virus evolvability derived from genotype-fitness maps in human and mosquito cells

Dengue virus (DENV), an arbovirus infecting over 100 million annually, cycles between human and mosquito hosts1. Examining how DENV adapts to such different host environments could uncover principles of arbovirus transmission and emergence. Here we combine sequential passaging and ultra-deep sequencing to examine the sequence dynamics and fitness changes of DENV populations adapting to human and mosquito cells, identifying the contributions of beneficial and deleterious mutations in shaping the fitness landscape driving host-specific paths of viral adaptation. We find DENV phenotypic adaptation is best described by the collective fitness contributions of all the alleles present in the population. Accordingly, while increased fitness during adaptation to each host is driven by host-specific beneficial mutations, it is reduced by the consistently replenished genetic load of deleterious mutations. Of note, host-specific beneficial mutations are in discrete regions across the genome, revealing molecular mechanisms of adaptation. Some of these clusters comprise phenotypically redundant mutations that may provide evolutionary robustness to transmission bottlenecks. Our results also suggest DENV adaptation is facilitated through variation in intrinsically disordered protein regions while transmembrane and structured domains evolve under stronger biophysical constraints. Importantly, the adaptation strategies uncovered in our simple system mirror macro-evolutionary changes observed across DENV serotypes and Zika virus and may suggest general principles of evolvability in arbovirus evolution.

microbiology↗

bioRxiv2018

Antiviral adaptive immunity and tolerance in the mosquito Aedes aegyti

Mosquitoes spread pathogenic arboviruses while themselves tolerate infection. We here characterize an immunity pathway providing long-term antiviral protection and define how this pathway discriminates between self and non-self. Mosquitoes use viral RNAs to create viral derived cDNAs (vDNAs) central to the antiviral response. vDNA molecules are acquired through a process of reverse-transcription and recombination directed by endogenous retrotransposons. These vDNAs are thought to integrate in the host genome as endogenous viral elements (EVEs). Sequencing of pre-integrated vDNA revealed that the acquisition process exquisitely distinguishes viral from host RNA, providing one layer of self-nonself discrimination. Importantly, we show EVE-derived piRNAs have antiviral activity and are loaded onto Piwi4 to inhibit virus replication. In a second layer of self-non-self discrimination, Piwi4 preferentially loads EVE-derived piRNAs, discriminating against transposon-targeting piRNAs. Our findings define a fundamental virus-specific immunity pathway in mosquitoes that uses EVEs as a potent and specific antiviral transgenerational mechanism.

immunology↗

bioRxiv2017

Long-read assembly of the Aedes aegypti genome reveals the nature of heritable adaptive immunity sequences

The Aedes aegypti mosquito is a major vector for arboviruses including dengue, chikungunya and Zika virus. Combating the spread of these viruses requires a more complete understanding of the mosquito immune system. Recent studies have implicated genomic endogenous viral elements (EVEs) derived from non-retroviral RNA viruses in insect immunity. Because these elements are inserted into repetitive regions of the mosquito genome, their large-scale structure and organization with respect to other genomic elements has been difficult to resolve with short-read sequencing. To better define the origin, diversity and biological role of EVEs, we employed single-molecule, real-time sequencing technology to generate a high quality, long-read assembly of the Ae. aegypti-derived Aag2 cell line genome. We leverage the quality and contiguity of this assembly to characterize the diversity and genomic context of EVEs in the genome of this important model system. We find that EVEs in the Aag2 genome are acquired through recombination by LTR retrotransposons, and organize into larger loci (>50kbp) characterized by high LTR density. These EVE containing loci are associated with increased transcription factor binding sight density and increased production of anti-genomic piRNAs. We also detected piRNA processing corresponding to on-going viral infection. This global view of EVEs and piRNA responses demonstrates the ubiquity and diversity of these heritable elements that define small-RNA mediated antiviral immunity in mosquitoes.

genomics↗