Biology subjects

Gillespie, K.

Publications and source records attributed to Gillespie, K..

4 recordsLinked to original sources

bioRxiv2025

Axonal growth of cortical neurons does not require paxillin

Axon growth is an essential cellular process during neural development, and its dysregulation contributes to numerous neurodevelopmental disorders. During axon growth, extracellular signals direct neurons to extend projections that connect with their synaptic targets. Paxillin is a key member of adhesion sites that control motility by linking the intracellular actin cytoskeleton to the extracellular matrix. Paxillin also binds to the cytoskeletal protein, tubulin. However, little is known about the role of adhesion proteins in neurons. Here, we use conditional paxillin knockout mice to investigate how loss of paxillin in pyramidal cortical neurons affects developing neuron morphology. Surprisingly, loss of paxillin in pyramidal cortical neurons caused no change in axon length or soma area between control (PxnF/F) and conditional paxillin knockout (PxnF/F; Emx1-Cre) mice at basal conditions. Following brain-derived neurotrophic factor stimulation, the loss of paxillin resulted in no change in soma area or axonal {beta}-tubulin levels, but did result in a significant increase in axon length, as compared to control. Finally, the corpus callosum size was not significantly different between PxnF/F and PxnF/F; Emx1-Cre animals. In summary, these data suggest that paxillin is not required for axonal growth during neural development.

neuroscience↗

bioRxiv2025

Differences in neutralization susceptibility between clade C HIV viruses from breastmilk versus contemporaneous circulating viruses from sexually acquired infections

HIV viruses that establish infection possess phenotypic and genotypic characteristics that have been selected for and that differ across transmission routes, including their susceptibility to broadly neutralizing antibodies (bnAbs). While sexually transmitted viruses have been well characterized, studies of vertically transmitted viruses are sparse and from cohorts that are often small in size and more than a decade old. To investigate whether viruses transmitted vertically during lactation possess distinct neutralization profiles compared to viruses transmitted sexually, we compared the neutralization sensitivity of 25 clade C breastmilk viruses to that of 99 contemporaneous clade C viruses from sera of adults with sexual acquisition against three bnAbs in clinical development.Three out of 7 breastmilk donors (43%) had one or more viruses resistant to 2 or more bnAbs, compared to 8 out of 99 (8%) contemporaneous adult viruses (p=0.02). Breastmilk viruses were more resistant to PGT121 and VRC07.523 (median IC80 >50 compared to 1.16 for PGT121, and 12.75 vs. 0.38 for VRC07.523; p=0.013 and <0.001 respectively), and more breastmilk viruses than adult viruses were resistant to VRC07.523 (94% vs. 43%, p=0.001). Interestingly, the breastmilk viruses most resistant to VRC07.523 had on average one or more glycans in V3 compared to adult transmitted viruses (median 3 vs. 2 glycosylation sites, including flanking position 295; p=0.009), and the number of V3 glycans was negatively correlated with VRC07.523 sensitivity (p=0.007). These findings highlight potential differences in bnAb susceptibility of vertically transmitted viruses and emphasize the need to increase sequencing efforts and screening of infant viruses to better inform the efficacy of candidate bnAbs to prevent vertical transmission of HIV.

immunology↗

bioRxiv2019

Protein Quality Control is a Risk Factor and Therapeutic Target in Toxin-Induced Biliary Atresia

BACKGROUND and AIMS Extra-hepatic biliary atresia (BA) is a pediatric liver disease with no approved medical therapy. Recent studies using human samples and experimental modeling suggest that glutathione redox metabolism and heterogeneity play a role in disease pathogenesis. We sought to dissect the mechanistic basis of liver redox variation and explore how other stress responses affect cholangiocyte injury in BA.METHODS We performed quantitative in situ hepatic glutathione redox mapping in zebrafish larvae carrying targeted mutations in glutathione metabolism genes and correlated these findings with sensitivity to the plant-derived BA-linked toxin biliatresone. We also determined whether genetic disruption of HSP90 protein quality control pathway genes implicated in human BA altered biliatresone toxicity in zebrafish and human cholangiocytes. An in vivo screen of a known drug library was performed to identify novel modifiers of cholangiocyte injury in the zebrafish experimental BA model with subsequent validation.RESULTS Glutathione metabolism gene mutations caused regionally distinct changes in the redox potential of cholangiocytes that differentially sensitized them to biliatresone. Disruption of human BA-implicated HSP90 pathway genes sensitized zebrafish and human cholangiocytes to biliatresone-induced injury independent of glutathione. Phosphodiesterase-5 inhibitors (PDE5i) and other cGMP signaling activators worked synergistically with the glutathione precursor N- acetylcysteine (NAC) in preventing biliatresone-induced injury in zebrafish and human cholangiocytes. PDE5i enhanced proteasomal degradation and required intact HSP90 chaperone.CONCLUSION Regional variation in glutathione metabolism underlies sensitivity to the biliary toxin biliatresone, and mirrors recently reported BA risk stratification linked to glutathione metabolism gene expression. Human BA can be causatively linked to genetic modulation of protein quality control. Combined treatment with NAC and cGMP signaling enhancers warrants further investigation as therapy for BA.Background and Context Biliary atresia (BA) is an obstructive fibrosing cholangiopathy that is the leading indication for liver transplantation in the pediatric population. There are no known treatments to prevent progressive liver injury after surgical restoration of bile flow.New Findings The authors identify factors that affect susceptibility of cholangiocytes to oxidative injury using a toxin-induced BA model. This information is used to validate genetic risk factors for human BA and identified PDE5i as a potential treatment for biliary atresia, either on its own or in combination with the anti-oxidant N-acetyl-cysteine.Limitations The work done in animal and cell culture models needs further study in human tissue-derived models and a larger cohort of BA patients.Impact The findings from this study provide a rationale for identifying new genetic risk factors that predispose to BA and for an interventional study to prevent progressive liver injury in this enigmatic disease.Short Summary This study uses zebrafish and human cell culture models to identify novel injury mechanisms, genetic risk factors and new therapies for the pediatric liver disease biliary atresia.Competing Interest StatementThe authors have declared no competing interest.Abbreviations17-AAG7-N-allylamino-17-demethoxygeldanamycin;BAbiliary atresia;bilbiliatresone;8-Br-cGMP8-Bromoguanosine 3’,5’-cyclic monophosphate;EHCextrahepatic cholangiocytes;Gclglutamate cysteine ligase;GGAgeranylgeranyl acetate;gsrglutathione reductase;GSHreduced glutathione;GSSGoxidized glutathione;IHCintrahepatic cholangiocytes;NACN-acetylcysteine;PDE5iPhosphodiesterase-5 inhibitors;PQCprotein quality control;WTwild-typeView Full Text

pathology↗

bioRxiv2018

Mass Mortality of Wood Frogs (Rana sylvatica) in the Ozark National Forest: Is it Acid Rain?

We describe observations of a continuing mass mortality event primarily involving wood frogs, but involving other amphibians to a lesser degree. The investigation took place from Spring 2000 through Spring 2004. No definitive correlations between environmental variables and mortality could be identified. Forensic analysis could not isolate causal pathogens. Although mortality fluctuated during the study, it may have spread to other species. Our report identifies population level problems in the eastern part of the Ozark National Forest but is unable to identify a cause. Future studies that more thoroughly address contaminants, pathogens/parasites, and other potential environmental problems in the Ozark National Forest are warranted.

ecology↗