Biology subjects

Coleman, A. K.

Publications and source records attributed to Coleman, A. K..

11 recordsLinked to original sources

bioRxiv2026

Loss of Mitochondrial Respiratory Capacity Reshapes Myeloid Cell Function during Mycobacterium tuberculosis infection

Myeloid cells are essential mediators of host defense against Mycobacterium tuberculosis (Mtb), yet the metabolic programs that sustain their function during chronic infection remain poorly defined. Here, using scRNA-seq we identified a striking, coordinated decline in mitochondrial electron transport chain gene expression across diverse myeloid populations as Mtb disease progressed in mice. This transcriptional remodeling was associated with broad changes in immune and metabolic pathways, including reduced antigen presentation, interferon responses, protein synthesis, and glycolysis. Accordingly, loss of Complex I in macrophages (Ndufs4 knockdown) reduced MHC-II surface expression, dysregulated inflammatory gene expression, and limited control of Mtb replication. Finally, analysis of single-cell transcriptomic data from Mtb-exposed human household contacts identified an almost identical transcriptional program enriched in IGRA+ individuals, supporting a role for mitochondrial respiratory remodeling in human TB. Together, these findings demonstrate that mitochondrial bioenergetic competence is required to sustain macrophage effector function during chronic Mtb infection and suggest that mitochondrial restoration may boost protective responses in TB patients.

immunology↗

bioRxiv2026

Mycobacterium tuberculosis manipulates host inflammation and lipid metabolism through the SET1-interacting protein Rv1075c

A growing body of literature supports a critical role for nucleomodulins, proteins that traffic to host cell nuclei and manipulate nuclear processes, in intracellular bacterial pathogenesis. Here, we identify the Mycobacterium tuberculosis (Mtb) secreted protein Rv1075c as a nucleomodulin that targets a histone modifying protein complex in macrophages. We report that {Delta}Rv1075c Mtb infection elicits a blunted transcriptional response in inflammatory and lipid metabolism pathways and fails to induce foamy macrophage formation in the lungs of infected mice. Using an unbiased mass-spectrometry based approach, we found that Rv1075c interacts with components of the H3K4me3-depositing SET1 histone methyltransferase complex, and that this interaction is required for Rv1075c nuclear localization. Consistent with Rv1075c inhibiting SET1 activity, SET1 deficiency results in hyperinduction of inflammatory genes in activated macrophages. Together, these findings reveal a mechanism by which Mtb engages host chromatin machinery and support a model whereby Rv1075c exploits the SET1 complex to promote a host environment conducive to mycobacterial persistence.

microbiology↗

bioRxiv2026

Mitochondrial STAT3-mediated suppression of apoptosis constrains antimycobacterial immunity

Maintenance of mitochondrial homeostasis is required to balance the host-pathogen interface during Mycobacterium tuberculosis (Mtb) infection. Here, we identify the non-canonical TRIM family member Trim14 as a critical regulator of mitochondrial integrity in Mtb-infected macrophages. Specifically, we demonstrate that Trim14 preserves mitochondrial membrane polarization and limits macrophage apoptosis by controlling phosphorylation and mitochondrial targeting of Stat3. When targeted to mitochondria, Stat3 restricts opening of the mitochondrial permeability transition pore, which raises the macrophage threshold for apoptotic commitment. In vivo, loss of Trim14 enhances apoptosis of macrophages and dendritic cells, leading to augmented antimycobacterial immunity marked by increased CD8+ T cell activation and effector function. Together, these findings define a Trim14-mitochondrial Stat3 axis that suppresses host-protective apoptosis during Mtb infection and pinpoint mitochondrial Stat3 as a potential target for therapies aimed at boosting antimycobacterial immunity. HIGHLIGHTSO_LITrim14 raises the apoptotic threshold in Mtb-infected macrophages. C_LIO_LITrim14 controls phosphorylation and mitochondrial targeting of Stat3. C_LIO_LIReduced mitochondrial Stat3 promotes mPTP opening and apoptotic commitment. C_LIO_LITrim14 deficiency enhances apoptosis, CD8+ T cell immunity, and Mtb resistance. C_LI

immunology↗

bioRxiv2025

HnRNPA2B1 tunes antimycobacterial immune responses in macrophages through alternative splicing of Irgm1

Onset and progression of active tuberculosis disease result from upsetting the delicate balance between Mtb virulence and host defenses. Because it dynamically tunes the functional output of protein expression in cells, alternative splicing, a process by which different mRNAs can be gen-erated from a single gene, is positioned to play a critical role in maintaining an equilibrated Mtb-macrophage host-pathogen interface. To gain insight into how alternative splicing shapes anti-mycobacterial immune responses, we used RNA-sequencing and splicing-aware computational pipelines to quantify alternative splicing in Mtb-infected bone marrow-derived murine macro-phages. We found that [~]5% of expressed macrophage genes exhibit one or more splicing changes at 8h post-Mtb infection, highlighting alternative splicing as a key regulatory node in the macrophage response to Mtb. We next sought to identify RNA binding proteins that play an out-sized role in shaping the macrophage transcriptome during Mtb infection. We discovered that the splicing factor heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) promotes the early induction of inflammatory genes while dampening several type I interferon-stimulated genes in response to Mtb. HnRNPA2B1 also controls alternative splicing of many genes during Mtb infection, including Irgm1, a critical immunity-related GTPase. The balance of Irgm1-long vs. -short is differentially regulated in response to diverse inflammatory cues and macrophages overexpressing Irgm1-short are defective in autophagosomal targeting, lysosomal homeostasis, and restriction of Mtb replication. These data highlight a key role for AS in shaping the macro-phage transcriptome and pinpoint hnRNPA2B1 as a novel restriction factor in the cell-intrinsic response to Mtb. IMPORTANCEAlthough the process of making proteins from RNAs requires many steps (transcription, cap-ping/polyadenylation, pre-mRNA splicing, mRNA export, mRNA modifications, etc.), we know very little about how post-transcriptional steps contribute to host immune defenses. Here, we show that alternative splicing, the process of making different mature RNAs from a single pre-cursor RNA, is a prominent and dynamic feature of macrophage infection with the bacterial pathogen Mycobacterium tuberculosis (Mtb). We identify the splicing regulator hnRNPA2B1 as a key coordinator of early gene expression during Mtb infection, influencing pathways that pro-mote inflammation and help restrict bacterial growth. Notably, we report that hnRNPA2B1 con-trols the splicing of the antimycobacterial protein Irgm1 to generate different flavors of the pro-tein. Since only one Irgm1 flavor can restrict Mtb growth inside macrophages, maintaining the balance of these proteins in response to diverse inflammatory cues is important. By revealing how RNA processing shapes the macrophage response to Mtb, our work highlights an often-overlooked layer of immune regulation and opens new avenues for splicing-targeted therapies designed to boost Mtb killing in macrophages.

microbiology↗

bioRxiv2024

LRRK2 kinase activity restricts NRF2-dependent mitochondrial protection in microglia

Mounting evidence supports a critical role for central nervous system (CNS) glial cells in neuroinflammation and neurodegenerative diseases, including Alzheimers disease (AD), Parkinsons Disease (PD), Multiple Sclerosis (MS), as well as neurovascular ischemic stroke. Previously, we found that loss of the PD-associated gene leucine-rich repeat kinase 2 (Lrrk2) in macrophages, peripheral innate immune cells, induced mitochondrial stress and elevated basal expression of type I interferon (IFN) stimulated genes (ISGs) due to chronic mitochondrial DNA engagement with the cGAS/STING DNA sensing pathway. Here, we report that loss of LRRK2 results in a paradoxical response in microglial cells, a CNS-specific macrophage population. In primary murine microglia and microglial cell lines, loss of Lrrk2 reduces tonic IFN signaling leading to a reduction in ISG expression. Consistent with reduced type I IFN, mitochondria from Lrrk2 KO microglia are protected from stress and have elevated metabolism. These protective phenotypes involve upregulation of NRF2, an important transcription factor in the response to oxidative stress and are restricted by LRRK2 kinase activity. Collectively, these findings illustrate a dichotomous role for LRRK2 within different immune cell populations and give insight into the fundamental differences between immune regulation in the CNS and the periphery.

immunology↗

bioRxiv2023

Na+/K+ATPase - Cav1.2 nanodomain differentially regulates intracellular and local adrenergic signaling in cardiac myocytes

BackgroundThe intracellular Na+ concentration ([Na+]i) is a crucial but understudied regulator of cardiac myocyte function. The Na+/K+ ATPase (NKA) controls the steady-state [Na+]i and thereby determines the set-point for intracellular Ca2+. Here, we investigate the nanoscopic organization and local adrenergic regulation of the NKA macromolecular complex and how it differentially regulates the intracellular Na+ and Ca2+ homeostases in atrial and ventricular myocytes. MethodsMulticolor STORM super-resolution microscopy, Western Blot analyses, and in vivo examination of adrenergic regulation are employed to examine the organization and function of Na+ nanodomains in cardiac myocytes. Quantitative fluorescence microscopy at high spatiotemporal resolution is used in conjunction with cellular electrophysiology to investigate intracellular Na+ homeostasis in atrial and ventricular myocytes. ResultsThe NKA1 (NKA1) and the L-type Ca2+-channel (Cav1.2) form a nanodomain with a center-to center distance of [~]65 nm in both ventricular and atrial myocytes. NKA1 protein expression levels are [~]3 fold higher in atria compared to ventricle. 100% higher atrial INKA, produced by large NKA "superclusters", underlies the substantially lower Na+concentration in atrial myocytes compared to the benchmark values set in ventricular myocytes. The NKAs regulatory protein phospholemman (PLM) has similar expression levels across atria and ventricle resulting in a much lower PLM/NKA1 ratio for atrial compared to ventricular tissue. In addition, a huge PLM phosphorylation reserve in atrial tissue produces a high {beta}-adrenergic sensitivity of INKA in atrial myocytes. {beta}-adrenergic regulation of INKA is locally mediated in the NKA1-Cav1.2 nanodomain via A-kinase anchoring proteins. ConclusionsNKA1, Cav1.2 and their accessory proteins form a structural and regulatory nanodomain at the cardiac dyad. The tissue-specific composition and local adrenergic regulation of this "signaling cloud" is a main regulator of the distinct global intracellular Na+ and Ca2+ concentrations in atrial and ventricular myocytes.

physiology↗

bioRxiv2023

Type I interferon expression requires transcriptional activation of IRF7 by the RNA binding protein SRSF7

Tight regulation of macrophage immune gene expression is required to fight infection without risking harmful inflammation. The contribution of RNA binding proteins (RBPs) to shaping the macrophage response to pathogens remains poorly understood. Transcriptomic analysis revealed that a member of the serine/arginine-rich (SR) family of mRNA processing factors, SRSF7, is required for optimal expression of a cohort of interferon stimulated genes (ISGs) in macrophages. Using genetic and biochemical assays, we discovered that in addition to its canonical role in regulating alternative splicing, SRSF7 drives transcription of interferon regulatory transcription factor 7 (IRF7) to promote antiviral immunity. At the Irf7 promoter, SRSF7 maximizes STAT1 transcription factor binding and RNA polymerase II elongation via cooperation with the H4K20me1 histone methyltransferase KMT5a (SET8). These studies define an unorthodox role for an SR protein in activating transcription and reveal an unappreciated RNA binding protein-chromatin network that orchestrates macrophage antiviral gene expression.

immunology↗

bioRxiv2022

Calcium and Bicarbonate Signaling Pathways have Pivotal, Resonating Roles in Matching ATP Production to Demand

Mitochondrial ATP production in cardiac ventricular myocytes must be continually adjusted to rapidly replenish the ATP consumed by the working heart. Two systems are known to be critical in this regulation: mitochondrial matrix Ca2+ ([Ca2+]m) and blood flow that is tuned by local ventricular myocyte metabolic signaling. However, these two regulatory systems do not account for the large physiological range of ATP consumption observed. We report here on the identity, location, and signaling cascade of a controversial third regulatory system -- CO2/bicarbonate. CO2 is generated in the mitochondrial matrix as a metabolic waste product produced by oxidation of nutrients which power the production of ATP. It is a lipid soluble gas that equilibrates with bicarbonate (HCO3-) in aqueous solutions. The bicarbonate level is tracked by a bicarbonate-activated adenylyl cyclase, soluble adenylyl cyclase (sAC). Using structural Airyscan super-resolution imaging and functional measurements we find that sAC is primarily inside the mitochondria of ventricular myocytes where it generates cAMP when activated by HCO3-. This cAMP signaling cascade is shown to operate inside the mitochondrial inter-membrane space (IMS) by activating local EPAC1 (Exchange Protein directly Activated by cAMP) which turns on Rap1 (Ras-related protein 1). Thus, mitochondrial ATP production is shown to be increased by bicarbonate-triggered sAC signaling through Rap1. Additional evidence is presented indicating that the cAMP signaling itself does not occur directly in the matrix. We also show that this third signaling process involving bicarbonate and sAC activates the cardiac mitochondrial ATP production machinery by working independently of, yet in conjunction with, [Ca2+]m-dependent ATP production to meet the energy needs of cellular activity in both health and disease. Thus, the resonant, or complementary effects of bicarbonate and [Ca2+]m signaling arms tune mitochondrial ATP production to match the full scale of energy consumption in cardiac ventricular myocytes.

physiology↗

bioRxiv2021

Mitochondrial dysfunction promotes alternative gasdermin D-mediated inflammatory cell death and susceptibility to infection

Human mutations in mitochondrial-associated genes are associated with inflammatory diseases and susceptibility to infection. However, their mechanistic contributions to immune outcomes remain ill-defined. We discovered that the disease-associated gain-of-function allele Lrrk2G2019S (leucine-rich repeat kinase 2) promotes mitochondrial hyper-fission, depolarization, and oxidative stress in macrophages. In the presence of Lrrk2G2019S-dependent mitochondrial perturbations, AIM2 inflammasome activation promotes more cell death but not more pyroptotic IL-1b release. Instead, inflammasome activation in Lrrk2G2019S macrophages triggers gasdermin D (GSDMD)-mediated mitochondrial pores, driving up ROS-mediated RIPK1/RIPK3/MLKL dependent necroptosis. Consequently, infection of Lrrk2G2019S mice with Mycobacterium tuberculosis elicits hyperinflammation and immunopathology via enhanced neutrophil infiltration. By uncovering that GSDMD promotes non-pyroptotic cell death in Lrrk2G2019S macrophages, our findings demonstrate that altered mitochondrial function can reprogram cell death modalities to elicit distinct immune outcomes. This provides mechanistic insights into why mutations in LRRK2 are associated with susceptibility to chronic inflammatory and infectious diseases. HIGHLIGHTSO_LIAltered mitochondrial homeostasis reprograms cell death modalities C_LIO_LIGSDMD associates with and depolarizes mitochondrial membranes following AIM2 activation C_LIO_LIGSDMD initiates a shift from pyroptotic to necroptotic cell death in Lrrk2G2019S macrophages C_LIO_LILrrk2G2019S elicits hyperinflammation and susceptibility to infection in flies and mice C_LI

immunology↗

bioRxiv2020

Heterologous flavivirus exposure provides varying degrees of cross-protection from Zika virus in a mouse model of infection

The 2015/16 Zika virus epidemic in South and Central America left the scientific community urgently trying to understand the disease and the factors which modulate Zika virus pathogenesis. Multiple other flaviviruses are endemic in areas where Zika virus emerged in 2015/16. Therefore, it is hypothesized that a key to understanding how Zika virus infection and disease progresses, is to study Zika virus infection in the context of prior flavivirus exposure. Humans and animal studies have highlighted the idea that having been previously exposed to a heterologous flavivirus may modulate the immune response to Zika virus. However, it is still unclear 1) how this impacts viral burden and pathology, and 2) the factors which correlate with the multiple metrics of disease. In this murine study, we longitudinally examine multiple factors involved in Zika disease, linking viral burden over time with increased neurological disease severity and weight loss. We show that prior heterologous flavivirus exposure with dengue virus type 2 or 3, or the vaccine strain of yellow fever, provides protection from mortality in a lethal Zika challenge. Reduction in viral burden and Zika disease in the context of prior flavivirus exposure varies depending on the infecting primary virus; with primary Zika infection being most protective from Zika challenge, followed by dengue 2, yellow fever, and dengue 3. This study demonstrates a protective effect of prior heterologous flavivirus exposure on Zika virus pathogenesis, and defines the relationship between prior flavivirus exposure and the potential for Zika virus disease. IMPORTANCEThe emergence and re-emergence of various vector-borne diseases in recent years highlights the need to understand the mechanisms of protection for each pathogen. In this study, we investigated the impact of prior exposure to Zika, dengue serotypes 2, 3, and the vaccine strain of yellow fever on pathogenesis and disease outcomes in a mouse model of Zika virus infection. We found that prior exposure to a heterologous flavivirus was protective from mortality, neurological disease, weight loss, and severe viral burden during a lethal Zika challenge. Using a longitudinal study design, we were able to link multiple disease parameters including viral burden over time with neurological disease severity and weight loss in the context of heterologous infection. This study demonstrates a role for heterologous flavivirus exposure in modulating flavivirus pathophysiology. Given the cyclic nature of most flavivirus outbreaks, this work will contribute to the forecasting of disease severity for future outbreaks.

microbiology↗

bioRxiv2020

Tubulin acetylation increases cytoskeletal stiffness to regulate mechanotransduction in striated muscle

Microtubules tune cytoskeletal stiffness to regulate the mechanics and mechanotransduction of striated muscle. While recent evidence suggests that microtubules enriched in detyrosinated α-tubulin are responsible for these effects in healthy muscle, and for their excess in disease, the possible contribution from several other α-tubulin modifications has not been investigated. Here we used genetic or pharmacologic strategies in isolated cardiomyocytes or skeletal myofibers to increase the level of acetylated α-tubulin without altering the level of detyrosinated α-tubulin. We show that microtubules enriched in acetylated α-tubulin contribute to the cytoskeletal stiffness and viscoelastic resistance, showing slowed rates of contraction and relaxation during unloaded contraction, and increased activation of NADPH Oxidase 2 (Nox2) by mechanotransduction. Together these findings add to growing evidence that microtubules contribute to the mechanobiology of striated muscle in health and disease.Competing Interest StatementThe authors have declared no competing interest.View Full Text

physiology↗