Biology subjects

Frank, A. M.

Publications and source records attributed to Frank, A. M..

4 recordsLinked to original sources

bioRxiv2025

A spatial gene expression signature of the mouse brain post-injury at the focal point of contusion

Traumatic brain injury (TBI) results from a primary injury that impacts the brain in a spatially-dependent manner. Here we investigated the topographical relationship of early transcriptional responses to a single, focal TBI in mice by controlled cortical impact (CCI). Guided by the presence of the anterior commissure (AC) in coronal sections at the rostro-caudal point of impact, we compared gene expression changes in the neocortex (CTX) and corpus callosum-external capsule (CC-EC), striatum (STR) and AC. Injury-induced gene expression changes were detected in the CTX, CC-EC and STR but not AC and were principally segregated based on cytoarchitecture, and secondarily by proximity to the site of impact. Additionally, unbiased spatial clustering revealed a positive relationship between proximity to the impact and the number of acutely differentially expressed genes within the laminar CTX. Gene pathways for interferon gamma response and for leukocyte-mediated migration and immunity were acutely enhanced across the injured CTX, CC-EC and STR. Within 1-week post-injury, transcriptional responses to injury in the CTX and CC-EC included gene pathways for adaptive T- and B-cell mediated immunity, whereas gene expression changes in the STR were largely resolved. Next, we examined the effects of systemic depletion of neutrophils and monocytes on spatial gene expression changes in the injured brain. This led to the upregulation of gene pathways functioning in synaptic transmission and an alternating down- and then upregulation of genes functioning in ribosomal messenger RNA translation and aerobic metabolism in mitochondria. These data suggest infiltrating neutrophils and monocytes play an evolving, multifaceted role in modulating the metabolic, transcriptional, and synaptic activity of brain tissue post-injury.

neuroscience↗

bioRxiv2024

Open and closed conformations of a sub-80 kDa Chagas vaccine candidate defined by a cryo-EM led integrative approach

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, remains a significant global public health concern. Despite its profound health impact in both endemic and non-endemic areas, no vaccine is available, and the existing therapies are outdated, producing severe side effects. The 80kDa prolyl oligopeptidase of Trypanosoma cruzi (TcPOP) has been recently identified as a leading candidate for Chagas vaccine development. We report the first three-dimensional structure of TcPOP in open and closed conformation, at a global resolution of 3.8 and 3.6 [A] respectively, determined using single-particle cryo-electron microscopy. Multiple conformations were observed and further characterized using plasmonic optical tweezers and hydrogen-deuterium exchange mass spectrometry. To assess the immunogenic potential of TcPOP, we immunized mice and evaluated both polyclonal and monoclonal responses against the TcPOP antigen and its homologues. The results revealed invasion blocking properties of anti-TcPOP polyclonal response via parasite lysis and its cross-reactivity versus closely-related POPs but not with human homologues. We were also able to produce and characterise three monoclonal antibodies, one of which showed neutralising properties and inhibition of parasite invasion via non-lytic mechanism. Collectively, our findings provide critical structural and functional insights necessary to understand the immunogenicity of TcPOP for future Chagas vaccine development and diagnostic applications.

biophysics↗

bioRxiv2023

High sugar diets can increase susceptibility to bacterial infection in Drosophila melanogaster

Overnutrition with dietary sugar can worsen infection outcomes in diverse organisms including insects and humans, generally through unknown mechanisms. In the present study, we show that adult Drosophila melanogaster fed high-sugar diets became more susceptible to infection by the Gram-negative bacteria Providencia rettgeri and Serratia marcescens, although diet had no significant effect on infection by Gram-positive bacteria Enterococcus faecalis or Lactococcus lactis. We found that P. rettgeri and S. marcescens proliferate more rapidly in D. melanogaster fed a high-sugar diet, resulting in increased probability of host death. D. melanogaster become hyperglycemic on the high-sugar diet, and we find evidence that the extra carbon availability may promote S. marcescens growth within the host. However, we found no evidence that increased carbon availability directly supports greater P. rettgeri growth. D. melanogaster on both diets fully induce transcription of antimicrobial peptide (AMP) genes in response to infection, but D. melanogaster provided with high-sugar diets show reduced production of AMP protein. Thus, overnutrition with dietary sugar may impair host immunity at the level of AMP translation. Our results demonstrate that dietary sugar can shape infection dynamics by impacting both host and pathogen, depending on the nutritional requirements of the pathogen and by altering the physiological capacity of the host to sustain an immune response. Author SummaryDiet has critical impact on the quality of immune defense, and high-sugar diets increase susceptibility to bacterial infection in many animals. Yet it is unknown which aspects of host and pathogen physiology are impacted by diet to influence infection dynamics. Here we show that high-sugar diets increase susceptibility to some, but not all, bacterial infections in Drosophila. We find that feeding on high sugar diet impairs the host immune response by reducing the level of antimicrobial peptides produced. The expression of genes encoding these peptides is not affected, so we infer that protein translation is impaired. We further show that flies on high-sugar diets are hyperglycemic, and that some pathogens may use the excess sugar in the host to promote growth during the infection. Thus, our study demonstrates that dietary impacts on infection outcome arise through physiological effects on both the host and pathogen.

immunology↗

bioRxiv2020

A Rare Deletion in SARS-CoV-2 ORF6 Dramatically Alters the Predicted Three-Dimensional Structure of the Resultant Protein

The function of the SARS-CoV-2 accessory protein p6, encoded by ORF6, is not fully known. Based upon its similarity to p6 from SARS-CoV, it may play a similar role, namely as an antagonist of type I interferon (IFN) signaling. Here we report the sequencing of a SARS-CoV-2 strain passaged six times after original isolation from a clinical patient in Hong Kong. The genome sequence shows a 27 nt in-frame deletion ({Delta}27,264-27,290) within ORF6, predicted to result in a 9 aa deletion ({Delta}FKVSIWNLD) from the central portion of p6. This deletion is predicted to result in a dramatic alteration in the three-dimensional structure of the resultant protein (p6{Delta}22-30), possibly with significant functional implications. Analysis of the original clinical sample indicates that the deletion was not present, while sequencing of subsequent passages of the strain identifies the deletion as a majority variant. This suggests that the deletion originated ab initio during passaging and subsequently propagated into the majority, possibly due to the removal of selective pressure through the IFN-deficient Vero E6 cell line. The specific function of the SARS-CoV-2 p6 N-terminus, if any, has not yet been determined. However, this deletion is predicted to cause a shift from N-endo to N-ecto in the transmembrane localization of the SARS-CoV-2 p6{Delta}22-30 N-terminus, possibly leading to the ablation of its native function.

genomics↗