Biology subjects

Coleman, L.

Publications and source records attributed to Coleman, L..

3 recordsLinked to original sources

bioRxiv2025

Cortical reactive microglia activate astrocytes, increasing neurodegeneration in human alcohol use disorder

Reactive microglia are associated with multiple brain diseases that may have specific disease phenotypes. Studies of human cortical microglia in alcohol use disorder (AUD) have characterized reactive microglial subtypes by transcriptome or histology. Preclinical studies have found proinflammatory signaling and microglia contribute to increases in alcohol drinking and preference, behaviors unique to AUD. This study of post-mortem human AUD combines microglial immunoreactivity (+IR) protein and changes in microglial gene expression (mRNA) in human orbital frontal cortex (OFC) in an effort to better characterize the reactive microglia associated with AUD. Since reactive microglia are linked to reactive astrocytes (GFAP+IR), oxidative DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG+IR), and neurodegeneration (NeuN, MAP2+IR), we assessed these markers within the OFC. AUD reactive microglia were identified by increases in Iba1, CD11b (Mac1-OX42), CX3CR1, CSF1R, CD68, CCR2, P2RY12, SYK, and TFE3+IR in AUD OFC compared to control moderate drinkers. Tmem119+IR was decreased in AUD brain. Several of these microglial genes had parallel changes in +IR protein and mRNA. However, several microglial markers commonly used to identify reactive microglia did not show changes in mRNA, including Iba1, CD68, P2RY12, and CSF1R+IR. Overall, AUD microglia show increases in monocyte phagocytic markers, but not TREM2, DAP, or complement genes. Reactive microglial markers were highly correlated with reactive astrocyte GFAP+IR, oxidative stress 8-OHdG+IR, and loss of neurons (NeuN, MAP2+IR). Mediation analysis indicated reactive microglia contribute to both reactive astrocytes and oxidative stress, but only reactive astrocytes were found to significantly contribute to loss of neurons (NeuN+IR). These findings are supported by mouse studies finding chronic ethanol exposure increases reactive astrocytes and oxidative stress that is inhibited by DREADD blockade of microglial activation. Our findings support a distinct AUD reactive microglial phenotype that activates astrocytes, contributing to AUD neurodegeneration and possibly heavy drinking.

pharmacology and toxicology↗

bioRxiv2021

Long-Range Electrostatic Interactions Significantly Modulate the Affinity of Dynein for Microtubules

The dynein family of microtubule minus-end directed motor proteins drives diverse functions in eukaryotic cells, including cell division, intracellular transport, and flagellar beating. Motor protein processivity, which characterizes how far a motor walks before detaching from its filament, depends on the interaction between its microtubule-binding domain (MTBD) and the microtubule. Dyneins MTBD switches between high- and low-binding affinity states as it steps. Significant structural and functional data show that specific salt bridges within the MTBD and between the MTBD and the microtubule govern these affinity state shifts. However, recent computational work suggests that non-specific, long-range electrostatic interactions between the MTBD and the microtubule may also play a significant role in the processivity of dynein. To investigate this hypothesis, we mutated negatively charged amino acids remote from the dynein MTBD-microtubule-binding interface to neutral residues and measured the binding affinity using microscale thermophoresis and optical tweezers. We found a significant increase in the binding affinity of the mutated MTBDs for microtubules. Furthermore, we found that charge screening by free ions in solution differentially affected the binding and unbinding rates of MTBDs to microtubules. Together, these results demonstrate a significant role for long-range electrostatic interactions in regulating dynein-microtubule affinity. Moreover, these results provide insight into the principles that potentially underlie the biophysical differences between molecular motors with various processivities and protein-protein interactions more generally. Statement of SignificanceThe dynein family of motor proteins drives the motility of multiple cellular functions by walking toward the minus end of microtubules. The biophysical mechanisms of dynein rely on its ability to change affinity for the microtubule as it steps. Specific short-range electrostatic interactions acting at the microtubule-binding domain (MTBD)-microtubule interface are known to govern binding affinity. This study shows that non-specific longer-range electrostatic interactions due to charged amino acids remote from the binding interface also contribute significantly to the binding affinity mechanisms. Our results suggest that subtle differences in the electrostatic charge distribution within the MTBD significantly affect the molecular biophysical motility mechanisms in the dynein family of motors.

biophysics↗

bioRxiv2017

Airway IRF7hi versus IRF7lo molecular response patterns determine clinical phenotypes in children with acute wheezing

Asthma exacerbations are triggered by rhinovirus infections. We employed a systems biology approach to delineate upper airway gene network patterns underlying asthma exacerbation phenotypes in children. Cluster analysis unveiled distinct IRF7hi versus IRF7lo molecular phenotypes, the former exhibiting robust upregulation of Th1/type I interferon responses and the latter an alternative signature marked by upregulation of cytokine and growth factor signalling and downregulation of interferon gamma. The two phenotypes also produced distinct clinical phenotypes. For IRF7lo versus IRF7hi: symptom duration prior to hospital presentation was more than twice as long from initial symptoms (p=0.011) and nearly three times as long for cough (p<0.001); the odds ratio of admission to hospital was increased more than four-fold (p=0.018); and time to recurrence was shorter (p=0.015). In summary, our findings demonstrate that asthma exacerbations in children can be divided into IRF7hi versus IRF7lo phenotypes with associated differences in clinical phenotypes.\n\nAbbreviationsAHR, airway hyperresponsiveness; ARG1, Arginase 1, CSF3, Colony Stimulating Factor 3; CD38, Cluster of Differentiation 38; CD163, Cluster of Differentiation 163; cDCs, conventional (or myeloid) dendritic cells; DDX60, DExD/H-Box Helicase 60; ED, Emergency Department; EGF, Epidermal Growth Factor; ERK, Extracellular signal-Regulated Kinase; FCER1G, Fc Fragment Of IgE Receptor Ig; HMBS, Hydroxymethylbilane Synthase; IFNg, Interferon Gamma; IFNL1, Interferon Lambda 1; IL-1R2, Interleukin 1 Receptor Type 2; IRF7, Interferon Regulatory Factor 7; ISG15, Interferon-stimulated gene 15; MDA5, Melanoma Differentiation-Associated protein 5; MX1, Myxovirus Resistance Protein 1; NAD, nicotinamide adenine dinucleotide; NCR1, Natural cytotoxicity triggering receptor 1; OSM, Oncostatin M; PD-L1, Programmed Death-Ligand 1; PPIA, Peptidylprolyl Isomerase A; PPIB Peptidylprolyl Isomerase B; RSAD2, Radical S-adenosyl methionine domain-containing protein 2; RSV, respiratory syncytial virus; RT-qPCR, quantitative reverse transcription PCR; RV, rhinovirus; sPLA2, secretory Phospholipase A2; TGFb, Transforming Growth Factor beta; THBS1, Thrombospondin 1; TNF, Tumor Necrosis Factor; TLR2, Toll-like Receptor 2.

cell biology↗