Biology subjects

Weindel, C. G.

Publications and source records attributed to Weindel, C. G..

9 recordsLinked to original sources

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↗

bioRxiv2026

Fragile X messenger ribonucleoprotein modulates IL-6 induction and inflammatory cell death in macrophages

RNA-binding proteins are key players in determining the fate of mRNA. One such RNA binding protein, Fragile X messenger ribonucleoprotein (FMRP), has an established role in RNA transcription, metabolism, translation, and degradation in the brain and reproductive system. Although FMRP is expressed in immune cells, little is known about how FMRP influences immune cell mRNA transcript outcomes. Here, we show that macrophage infection with the intracellular pathogen Listeria monocytogenes induces FMRP translocation from the cytoplasm to the nucleus. We show that infected macrophages lacking FMRP have impaired Il6 induction in response to L. monocytogenes infection. Finally, we show that macrophages lacking FMRP have increased susceptibility to inflammatory cell death. Together, these data implicate FMRP in modulating proinflammatory gene expression during bacterial infection.

immunology↗

bioRxiv2024

Necrosis drives susceptibility to Mycobacterium tuberculosis in POLG mtDNA mutator mice

The genetic and molecular determinants that underlie the heterogeneity of Mycobacterium tuberculosis (Mtb) infection outcomes in humans are poorly understood. Multiple lines of evidence demonstrate that mitochondrial dysfunction can exacerbate mycobacterial disease severity and mutations in some mitochondrial genes confer susceptibility to mycobacterial infection in humans. Here, we report that mutations in mitochondria DNA (mtDNA) polymerase gamma (POLG) potentiate susceptibility to Mtb infection in mice. PolgD257A mutator mtDNA mice fail to mount a protective innate immune response at an early infection timepoint, evidenced by high bacterial burdens, reduced M1 macrophages, and excessive neutrophil infiltration in the lungs. Immunohistochemistry reveals signs of enhanced necrosis in the lungs of Mtb-infected PolgD257A mice and PolgD257A mutator macrophages are hyper-susceptible to extrinsic triggers of necroptosis ex vivo. By assigning a role for mtDNA mutations in driving necrosis during Mtb infection, this work further highlights the requirement for mitochondrial homeostasis in mounting balanced immune responses to Mtb.

immunology↗

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

The RNA binding protein, HNRNPA2B1, regulates IFNG signaling in macrophages

Heterogeneous nuclear ribonucleoprotein A2B1 (HNRNPA2B1) is a well known RNA binding protein but the mechanisms by which it contributes to innate immune gene regulation are poorly understood. Here we report that HNRNPA2B1 functions in macrophages to regulate IFNG (IFN-{gamma}) signaling through alternative splicing of the IFNG receptor. Specific deletion of HNRNPA2B1 in macrophages resulted in altered cytokine responses in both an endotoxic shock model and following Salmonella infection. Interestingly, while HNRNPA2B1 can function as a viability gene, we observed increased macrophage and neutrophil numbers in the KO mice following LPS induced endotoxic shock. We also discovered that HNRNPA2B1 restricts replication of Salmonella enterica in vivo. Mechanistically, loss of HNRNPA2B1 resulted in an increase in NGO transcripts, which lack a start codon, of the IFNG receptor (Ifngr) leading to lower expression of the receptor at the cell surface impacting the downstream IFNG signaling cascade. Collectively, our data highlight an important role for HNRNPA2B1 in regulating IFNG signaling and restricting intracellular bacterial pathogens in macrophages.

immunology↗

bioRxiv2023

Macrophage innate immune gene expression requires dynamic regulation of the nuclear paraspeckle

To ensure a robust immune response to pathogens without risking immunopathology, the kinetics and amplitude of inflammatory gene expression in macrophages needs to be exquisitely well-controlled. There is a growing appreciation for stress-responsive membraneless organelles (MLOs) regulating various steps of eukaryotic gene expression in response to extrinsic cues. Here, we implicate the nuclear paraspeckle, a highly ordered biomolecular condensate that nucleates on the Neat1 lncRNA, in tuning innate immune gene expression in murine macrophages. In response to a variety of innate agonists, macrophage paraspeckles rapidly aggregate (0.5 h post-stimulation) and disaggregate (2h post-stimulation). Paraspeckle maintenance and aggregation require active transcription and MAPK signaling whereas paraspeckle disaggregation requires degradation of Neat1 via the nuclear RNA exosome. Expression of a large cohort of cytokines, chemokines, and antimicrobial mediators is compromised in lipopolysaccharide-treated macrophages lacking Neat1, resulting in a failure to express a cohort of pro-inflammatory cytokines, chemokines, and antimicrobial mediators. Consequently, Neat1 KO macrophages cannot control replication of Salmonella enterica serovar Typhimurium or vesicular stomatitis virus. These findings highlight a prominent role for MLOs in orchestrating the macrophage response to pathogens and support a model whereby dynamic assembly and disassembly of paraspeckles reprograms the nuclear RNA binding protein landscape to enable inflammatory gene expression following innate stimuli. SIGNIFICANCE STATEMENTTo mount appropriate immune responses and fight infection, macrophages need to sense and respond to pathogen-associated signals with incredible precision. Membraneless organelles (MLOs) are complexes of RNAs and proteins that change in size, shape, and abundance in response to extracellular signals. We hypothesized that an MLO called the nuclear paraspeckle helps macrophages initiate and calibrate innate immune gene expression during infection. We found that paraspeckles rapidly aggregate and then dissolve in macrophages following pathogen sensing. Macrophages lacking paraspeckles cannot properly induce inflammatory genes, resulting in a failure to control replication of intracellular bacterial and viral pathogens. These data suggest that altered paraspeckle dynamics may dysregulate inflammatory gene expression in a variety of human diseases.

immunology↗

bioRxiv2022

SRSF6 balances mitochondrial-driven innate immune outcomes through alternative splicing of BAX

To mount a protective response to infection while preventing hyperinflammation, gene expression in innate immune cells must be tightly regulated. Despite the importance of pre-mRNA splicing in shaping the proteome, its role in balancing immune outcomes remains understudied. Transcriptomic analysis of murine macrophage cell lines identified Serine/Arginine Rich Splicing factor 6 (SRSF6) as a gatekeeper of mitochondrial homeostasis. SRSF6 orchestrates this by directing alternative splicing of the mitochondrial pore-forming protein BAX. Loss of SRSF6 promotes accumulation of BAX-{kappa}, a variant that sensitizes macrophages to undergo cell death and triggers upregulation of interferon stimulated genes through cGAS sensing of cytosolic mitochondrial DNA. Upon pathogen sensing, macrophages regulate SRSF6 expression to control the liberation of immunogenic mtDNA and adjust the threshold for entry into programmed cell death. This work defines BAX alternative splicing by SRSF6 as a critical node not only in mitochondrial homeostasis, but also in the macrophages response to pathogens.

molecular biology↗

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↗

bioRxiv2019

LRRK2 regulates innate immune responses and neuroinflammation during Mycobacterium tuberculosis infection

Despite many connections between mutations in leucine-rich repeat kinase 2 (LRRK2) and susceptibility to mycobacterial infection, we know little about its function outside of the brain, where it is studied in the context of Parkinsons Disease (PD). Here, we report that LRRK2 controls peripheral macrophages and brain-resident glial cells ability to respond to and express inflammatory molecules. LRRK2 KO macrophages express elevated basal levels of type I interferons, resulting from defective purine metabolism, mitochondrial damage, and engagement of mitochondrial DNA with the cGAS DNA sensing pathway. While LRRK2 KO mice can control Mycobacterium tuberculosis (Mtb) infection, they exhibit exacerbated lung inflammation and altered activation of glial cells in PD-relevant regions of the brain. These results directly implicate LRRK2 in peripheral immunity and support the \"multiple-hit hypothesis\" of neurodegenerative disease, whereby infection coupled with genetic defects in LRRK2 create an immune milieu that alters activation of glial cells and may trigger PD.

immunology↗