Biology subjects

Moe, A.

Publications and source records attributed to Moe, A..

8 recordsLinked to original sources

bioRxiv2026

A self-organized signaling hierarchy patterns the cortex during cell repair

Cells generate dynamic patterns of Rho GTPase activation to direct the subsequent patterning of Rho GTPase effectors needed to remodel the cell cortex during processes ranging from cell division to cell repair. To understand how such patterns arise, we used live cell imaging, time-resolved Rho GTPase manipulations, and a novel computational tool to study the spatiotemporal dynamics of Rho, Cdc42 and several downstream Cdc42 targets in wounded Xenopus laevis oocytes. We find that the characteristic wound-induced segregation of Rho and Cdc42 activity into concentric zones is followed by polarization of the Cdc42 zone such that Toca-1 progressively concentrates at the back of the Cdc42 zone while Arp2/3, cofilin, cortactin, and the Rho GAP p190RhoGAP progressively concentrate at the front of the Cdc42 zone, where it overlaps the Rho zone. Remarkably, the juxtaposition of Rho activity to Cdc42 is required for the polarization of p190RhoGAP, while p190RhoGAP is responsible for establishing the boundary between the Cdc42 and Rho zones. The results indicate that the characteristic segregation of the Rho and Cdc42 zones, as well as the polarization of the Cdc42 zone, arise from cortical self-organization. Further, these findings reveal a simple mechanism for hierarchical establishment of cortical patterns: recruitment of new proteins to regions of signaling compartment overlap.

cell biology↗

bioRxiv2026

Anomalous Emotion Regulation & Reward Network Connectivity Underlying Suicidal & Non-Suicidal Self-Injury in Early Psychosis

BackgroundIndividuals with early psychosis (EP) have elevated risk for suicide, the leading cause of death in the first five years following diagnosis. Non-suicidal self-injury (NSSI) significantly predicts suicidal behavior, yet studies of self-injury often exclude participants with psychosis. We investigated effective connectivity in emotion regulation and reward network regions among participants with lifetime history of NSSI or suicide attempt (SA) with and without EP. MethodsResting-state fMRI data were acquired for 23 individuals with EP and 34 non-clinical controls (NCC). We estimated effective connectivity models for regions implicated in the self-injury literature: middle cingulate cortex (MCC), posterior cingulate cortex (PCC), caudate, putamen, posterior superior temporal gyrus (STG), orbitofrontal cortex (OFC), and insula. There were 3 models characterizing different groupings: diagnosis (NCC vs. EP); NSSI (present[+], n=21 vs. absent[-], n=36); and SA (present[+], n=21 vs. absent[-], n=36). ResultsEP was associated with increased STG to PCC and insula to putamen connectivity. NSSI+ (n=7 NCC, 14 EP) had increased PCC to insula lagged connectivity and increased contemporaneous bilateral putamen activity, relative to NSSI- (n=27 NCC, 9 EP). NSSI was positively correlated with lagged insula to putamen activity (p=0.016). SA and NSSI were associated with reduced PCC to caudate connectivity. ConclusionNSSI is associated with increased connectivity within emotion regulation regions and disrupted connectivity between emotion regulation and reward networks modulated by the STG and striatum. Findings are consistent with broader self-injury literature, supporting the utility of using similar interventions from other disorders to address self-injury within EP.

neuroscience↗

bioRxiv2023

MICROGLIAL CELL EXPRESSION OF THE TYPE 2 CANNABINOID RECEPTOR REGULATES IMMUNE-MEDIATED NEUROINFLAMMATION

Neuroinflammation is a recognized complication of immunotherapeutic approaches such as immune checkpoint inhibitor treatment, chimeric antigen receptor therapy, and graft versus host disease (GVHD) occurring after allogeneic hematopoietic stem cell transplantation. While T cells and inflammatory cytokines play a role in this process, the precise interplay between the adaptive and innate arms of the immune system that propagates inflammation in the central nervous system remains incompletely understood. Using a murine model of GVHD, we demonstrate that type 2 cannabinoid receptor (CB2R) signaling plays a critical role in the pathophysiology of neuroinflammation. In these studies, we identify that CB2R expression on microglial cells induces an activated inflammatory phenotype which potentiates the accumulation of donor-derived proinflammatory T cells, regulates chemokine gene regulatory networks, and promotes neuronal cell death. Pharmacological targeting of this receptor with a brain penetrant CB2R inverse agonist/antagonist selectively reduces neuroinflammation without deleteriously affecting systemic GVHD severity. Thus, these findings delineate a therapeutically targetable neuroinflammatory pathway and has implications for the attenuation of neurotoxicity after GVHD and potentially other T cell-based immunotherapeutic approaches.

immunology↗

bioRxiv2022

A TYPE 2 INNATE LYMPHOID CELL-INTERLEUKIN 9 CIRCUIT INDUCES PANETH CELL METAPLASIA AND SMALL INTESTINAL REMODELING

Paneth cell metaplasia (PCM) typically arises in the setting of pre-existing gastrointestinal (GI) diseases; however, the mechanistic pathway that induces metaplasia and whether PCM is initiated exclusively by disorders intrinsic to the GI tract has not been delineated. Herein, we describe the development of PCM in a murine model of inducible bcr/abl oncogene-driven chronic myelogenous leukemia (CML) in which metaplasia is causally and temporally linked to the development of leukemia. Mechanistically, CML induced a proinflammatory state within the GI tract that resulted in the production of epithelial-derived IL-33. Binding of IL-33 to ST2 led to the production of IL-9 by type 2 innate lymphoid cells (ILC2s) which was directly responsible for the induction of PCM in the colon and Paneth cell hyperplasia in the ileum. In addition, IL-9 directed remodeling of the small intestines characterized by goblet and tuft cell hyperplasia along with the expansion of mucosal mast cells. Thus, we identify that an extra intestinal disease can trigger an ILC2/IL-9 immune circuit which induces PCM and regulates epithelial cell fate decisions in the GI tract.

immunology↗

bioRxiv2022

Structural basis of mammalian Complex IV inhibition by steroids

The mitochondrial electron transport chain maintains the proton motive force that powers ATP synthesis. The energy for this process comes from oxidation of NADH and succinate, with the electrons from this oxidation passed via intermediate carriers to oxygen. Complex IV (CIV), the terminal oxidase, transfers electrons from the intermediate electron carrier cytochrome c to oxygen, contributing to the proton motive force in the process. Within CIV, protons move through the K- and D-pathways during turnover. The former is responsible for transferring two protons to the enzymes catalytic site upon reduction of the site, where they eventually combine with oxygen and electrons to form water. CIV is the main site for respiratory regulation, and although previous studies showed that steroid-binding can regulate CIV activity little is known about how this regulation occurs. Here we characterize the interaction between CIV and steroids using a combination of kinetic experiments, structure determination, and molecular simulations. We show that molecules with a sterol moiety, such as glyco-diosgenin and cholesteryl hemisuccinate, reversibly inhibit CIV. Flash photolysis experiments probing the high-speed equilibration of electrons within CIV demonstrate that binding of these molecules inhibits proton uptake through the K-pathway. Single particle cryo-EM of CIV with glyco-diosgenin reveals a previously undescribed steroid-binding site adjacent to the K-pathway, and molecular simulations suggest that the steroid binding modulates the conformational dynamics of key residues and proton transfer kinetics within this pathway. The binding pose of the sterol group sheds light on possible structural gating mechanisms in the CIV catalytic cycle. SIGNIFICANCE STATEMENTMammalian complex IV (CIV), the final complex of the mitochondrial electron transport chain, uses electrons from cytochrome c to reduce oxygen to water, driving aerobic life. Although CIV functions as the main site for respiratory regulation, there is little structural or biochemical information on how this regulation occurs. Previous studies provided evidence of CIV regulation by steroids, but the steroid binding site and regulatory mechanism remain unclear. Using single particle cryogenic electron microscopy, we discover the binding site of the steroid-derived detergent, glyco-diosgenin. Results from flash photolysis kinetic experiments with CIV in the presence of glyco-diosgenin and cholesterol hemisuccinate are combined with cryo-EM and molecular simulations to elucidate how steroid binding limits proton uptake by the complex.

biophysics↗

bioRxiv2021

The respiratory supercomplex from C. glutamicum

Corynebacterium glutamicum is a preferentially aerobic Gram-positive bacterium belonging to the Actinobacteria phylum, which also includes the pathogen Mycobacterium tuberculosis. In the respiratory chain of these bacteria, complexes III (CIII) and IV (CIV) form a CIII2CIV2 supercomplex that catalyzes oxidation of menaquinol and reduction of dioxygen to water. Electron transfer within the CIII2CIV2 supercomplex is linked to transmembrane proton translocation, which maintains an electrochemical proton gradient that drives ATP synthesis and transport processes. We isolated the C. glutamicum supercomplex and used cryo-EM to determine its structure at 2.9 [A] resolution. The structure shows a central CIII2 dimer flanked by a CIV on each side. One menaquinone is bound in each of the QN and QP sites in each CIII, near the cytoplasmic and periplasmic sides, respectively. In addition, we identified a menaquinone positioned ~14 [A] from heme bL on the periplasmic side. A di-heme cyt. cc subunit provides an electronic connection between each CIII monomer and the adjacent CIV. In CIII2, the Rieske iron-sulfur (FeS) proteins are positioned with the iron near heme bL. Multiple subunits interact to form a convoluted sub-structure at the cytoplasmic side of the supercomplex, which defines a novel path that conducts protons into CIV.

biochemistry↗

bioRxiv2020

Cryo-EM structure and kinetics reveal electron transfer by 2D diffusion of cytochrome c in the yeast III-IV respiratory supercomplex

Energy conversion in aerobic organisms involves an electron current from low-potential donors, such as NADH and succinate, to dioxygen through the membrane-bound respiratory chain. Electron transfer is coupled to transmembrane proton transport that maintains the electrochemical proton gradient used to produce ATP and drive other cellular processes. Electrons are transferred between respiratory complexes III and IV (CIII and CIV) by water-soluble cyt. c. In S. cerevisiae and some other organisms, these complexes assemble into larger CIII2CIV1/2 supercomplexes, the functional significance of which has remained enigmatic. In this work, we measured the kinetics of the S. cerevisiae supercomplexs cyt.c-mediated QH2:O2 oxidoreductase activity under various conditions. The data indicate that the electronic link between CIII and CIV is confined to the surface of the supercomplex. Cryo-EM structures of the supercomplex with cyt. c reveal distinct states where the positively-charged cyt. c is bound either to CIII or CIV, or resides at intermediate positions. Collectively, the structural and kinetic data indicate that cyt. c travels along a negatively-charged surface patch of the supercomplex. Thus, rather than enhancing electron-transfer rates by decreasing the distance cyt. c must diffuse in 3D, formation of the CIII2CIV1/2 supercomplex facilitates electron transfer by 2D diffusion of cyt. c. This mechanism enables the CIII2CIV1/2 supercomplex to increase QH2:O2 oxidoreductase activity and suggests a possible regulatory role for supercomplex formation in the respiratory chain. Significance StatementIn the last steps of food oxidation in living organisms, electrons are transferred to oxygen through the membrane-bound respiratory chain. This electron transfer is mediated by mobile carriers such as membrane-bound quinone and water-soluble cyt. c. The latter transfers electrons from respiratory complex III to IV. In yeast these complexes assemble into III2IV1/2 supercomplexes, but their role has remained enigmatic. This study establishes a functional role for this supramolecular assembly in the mitochondrial membrane. We used cryo-EM and kinetic studies to show that cyt. c shuttles electrons by sliding along the surface of III2IV1/2 (2D diffusion). The structural arrangement into III2IV1/2 supercomplexes suggests a mechanism to regulate cellular respiration.

biochemistry↗

bioRxiv2019

A simple pressure-assisted method for cryo-EM specimen preparation

Micro-crystal electron diffraction (MicroED) has shown great potential for structure determination of macromolecular crystals too small for X-ray diffraction. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing MicroED specimens, named Preassis, in which excess liquid is removed through an EM grid with the assistance of pressure. We show the ice thicknesses can be controlled by tuning the pressure in combination with EM grids with appropriate hole sizes. Importantly, Preassis can handle a wide range of protein crystals grown in various buffer conditions including those with high viscosity, as well as samples with low crystal contents. Preassis is a simple and universal method for MicroED specimen preparation, and will significantly broaden the applications of MicroED.

molecular biology↗