Biology subjects

Read, T.-A.

Publications and source records attributed to Read, T.-A..

7 recordsLinked to original sources

bioRxiv2026

A hyperactivating mutation in formin-like 2 causes brain and vertebrae defects

Formins are a group of proteins that nucleate and polymerize actin monomers into filaments to promote cell morphology and migration. Mutations in formin-encoding genes cause a broad spectrum of human diseases, ranging from kidney disease to non-syndromic intellectual disability. Through a forward genetics screen, we identified a mouse strain (nmf418) with a homozygous mutation in a splice acceptor in Fmnl2 that causes hindlimb motor dysfunction, enlarged midbrain colliculi, cerebellar hypoplasia, and vertebral abnormalities in the thoracolumbar spinal cord. The nmf418 mutation causes skipping of exon 10, which encodes a portion of the diaphanous inhibitory domain (DID) required for FMNL2 autoinhibition, and results in dramatically lower FMNL2 protein levels. Consistent with a gain-of-function mechanism, mutant FMNL2 has altered enrichment at filopodia tips, increased actin polymerization activity, and its expression results in enhanced cell migration in vitro. Furthermore, none of the neural or skeletal phenotypes were recapitulated in Fmnl2 knockout mice. Transcriptomic analysis of the embryonic cerebellum suggests that complete loss of Fmnl2 triggers broad compensatory upregulation of actin regulatory pathways, while expression of mutant FMNL2 is associated with dysregulation of cell migration, motility pathways, and calcium homeostasis pathways. Taken together, these findings suggest that Fmnl2 is largely dispensable for overall mouse development but that its autoregulation is essential for proper formation of the mouse nervous and skeletal systems.

genetics↗

bioRxiv2024

Endothelial Drp1 Couples VEGF-induced Redox Signaling with Glycolysis Through Cysteine Oxidation to Drive Angiogenesis

Angiogenesis plays a vital role for postnatal development and tissue repair following ischemia. Reactive oxygen species (ROS) generated by NADPH oxidases (NOXes) and mitochondria act as signaling molecules that promote angiogenesis in endothelial cells (ECs) which mainly relies on aerobic glycolysis for ATP production. However, the connections linking redox signaling with glycolysis are not well understood. The GTPase Drp1 is a member of the dynamin superfamily that moves from cytosol to mitochondria through posttranslational modifications to induce mitochondrial fission. The role of Drp1 in ROS-dependent VEGF signaling and angiogenesis in ECs has not been previously described. Here, we identify an unexpected function of endothelial Drp1 as a redox sensor, transmitting VEGF-induced H2O2 signals to enhance glycolysis and angiogenesis. Loss of Drp1 expression in ECs inhibited VEGF-induced angiogenic responses. Mechanistically, VEGF rapidly induced the NOX4-dependent sulfenylation (CysOH) of Drp1 on Cys644, promoting disulfide bond formation with the metabolic kinase AMPK and subsequent sulfenylation of AMPK at Cys299/304 via the mitochondrial fission-mitoROS axis. This cysteine oxidation of AMPK, in turn, enhanced glycolysis and angiogenesis. In vivo, mice with EC-specific Drp1 deficiency or CRISPR/Cas9-engineered "redox-dead" (Cys to Ala) Drp1 knock-in mutations exhibited impaired retinal angiogenesis and post-ischemic neovascularization. Our findings uncover a novel role for endothelial Drp1 in linking VEGF-induced mitochondrial redox signaling to glycolysis through a cysteine oxidation-mediated Drp1-AMPK redox relay, driving both developmental and reparative angiogenesis.

cell biology↗

bioRxiv2023

Control of microtubules in neuronal processes by profilin 1 and actomyosin

Microtubules, intermediate filaments, and actin are cytoskeletal polymer networks found within the cell. While each has unique functions, all the cytoskeletal elements must work together for cellular mechanics to be fully operative. This is achieved through crosstalk mechanisms whereby the different networks influence each other through signaling pathways and direct interactions. Because crosstalk can be complex, it is possible for perturbations in one cytoskeletal element to affect the others in ways that are difficult to predict. Here we investigated how long-term changes to the actin cytoskeleton affect microtubules and intermediate filaments. Reducing F-actin or actomyosin contractility increased acetylated microtubules and intermediate filament expression, with the effect being significantly more pronounced in neuronal processes. Changes to microtubules were completely reversible if F-actin and myosin activity is restored. Moreover, the altered microtubules in neuronal processes resulting from F-actin depletion caused significant changes to microtubule-based transport, mimicking phenotypes that are linked to neurodegenerative disease. Thus, defects in actin dynamics cause a compensatory response in other cytoskeleton components which profoundly alters cellular function.

cell biology↗

bioRxiv2023

The actin binding protein profilin 1 is critical for mitochondria function

Profilin 1 (PFN1) is an actin binding protein that is vital for the polymerization of monomeric actin into filaments. Here we screened knockout cells for novel functions of PFN1 and discovered that mitophagy, a type of selective autophagy that removes defective or damaged mitochondria from the cell, was significantly upregulated in the absence of PFN1. Despite successful autophagosome formation and fusion with the lysosome, and activation of additional mitochondrial quality control pathways, PFN1 knockout cells still accumulate damaged, dysfunctional mitochondria. Subsequent imaging and functional assays showed that loss of PFN1 significantly affects mitochondria morphology, dynamics, and respiration. Further experiments revealed that PFN1 is located to the mitochondria matrix and is likely regulating mitochondria function from within rather than through polymerizing actin at the mitochondria surface. Finally, PFN1 mutants associated with amyotrophic lateral sclerosis (ALS) fail to rescue PFN1 knockout mitochondrial phenotypes and form aggregates within mitochondria, further perturbing them. Together, these results suggest a novel function for PFN1 in regulating mitochondria and identify a potential pathogenic mechanism of ALS-linked PFN1 variants.

cell biology↗

bioRxiv2021

TDAExplore: quantitative image analysis through topology-based machine learning

Machine learning has greatly expanded the ability to classify images. However, many machine learning classifiers require thousands of images for training and lack quantitative descriptors of how images were grouped. We overcome these limitations with a machine learning approach based on topological data analysis, where a data set of 20-30 images is sufficient to accurately train the classifier. Our method quantifies differences between groups and identifies subcellular regions with the largest dissimilarities.

cell biology↗

bioRxiv2019

Profilin 1 Controls the Assembly, Organization, and Dynamics of Leading Edge Actin Structures Through Internetwork Competition and Collaboration

How actin monomers are distributed to different networks remains poorly understood. One emerging concept is that the monomer pool is limited and heterogenous, causing biased assembly and internetwork competition. However, most knowledge regarding monomer distribution comes from studies where competing networks are discrete. In metazoans, many actin-based structures are complex, containing competing networks that overlap and are functionally interdependent. Addressing how monomers control the assembly and organization of these complex structures is critical to understanding how actin functions in cells. Here, we identify the monomer-binding protein profilin 1 (PFN1) as a major determinant of actin assembly, organization, and network homeostasis in mammalian cells. At the leading edge, PFN1 controls the localization and activity of the assembly factors Arp2/3 and Mena/VASP, with discrete stages of internetwork competition and collaboration occurring at different PFN1 concentrations. This causes substantial changes to leading edge actin architecture and the types of structures that form there.

cell biology↗

bioRxiv2018

Enhanced Neurite Outgrowth and Regeneration in ALS Resistant Motor Neurons from SOD1 Mutant Mouse Models

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease characterized by motor neuron cell death. However, not all motor neurons are equally susceptible. Most of what we know about the surviving motor neurons comes from gene expression profiling, less is known about their functional traits. We found that resistant motor neurons cultured from SOD1 ALS mouse models have enhanced axonal outgrowth and dendritic branching. They also have an increase in the number and size of actin-based structures like growth cones and filopodia. These phenotypes occur in cells cultured from presymptomatic mice and mutant SOD1 models that do not develop ALS, but not in embryonic motor neurons. Enhanced outgrowth and upregulation of filopodia can be induced in wild-type adult cells by expressing mutant SOD1. These results demonstrate that mutant SOD1 can enhance the regenerative capability of ALS resistant motor neurons. Capitalizing on this mechanism could lead to new therapeutic strategies.

neuroscience↗