Biology subjects

Feole, M.

Publications and source records attributed to Feole, M..

5 recordsLinked to original sources

bioRxiv2026

Differentiation protocol and maturation shape the axial identity and synaptic state in human iPSC-derived spinal motor neurons

Human induced pluripotent stem cell (iPSC)-derived motor neurons are widely used for disease modeling. Stem cells can be differentiated into motor neurons by exposure to specific patterning morphogens, which can ultimately determine terminal cellular composition and developmental state. We compared two small molecule workflows for human iPSC maturation into motor neurons: a rapid direct protocol (diMN protocol) and an extended protocol (purMN protocol), with both protocols matched for 20 days in maturation medium. While the diMN protocol generated mixed neural cultures, the purMN protocol provided cultures with greater motor neuron enrichment, stronger caudal spinal identity, broader synaptic and cholinergic programs, and reduced progenitor-associated signatures. By extending the purMN protocol to 32 days in maturation media, cultures developed reinforced spinal, postsynaptic, presynaptic, calcium-signaling, and cholinergic features. Across four independent reference frameworks, deconvolution aligned diMN cultures with anterior and progenitor-associated states and purMN cultures with spinal and post-mitotic states. In a microfluidic co-culture system, purMNs formed denser, more highly branched distal neurite networks and produced more innervated acetylcholine receptor clusters compared to diMNs. Revealing how purity and maturation jointly define the transcriptomic and structural state of human iPSC-derived spinal motor neuron cultures will help the field choose optimal models for studies of neurodevelopment and neurodegenerative diseases.

neuroscience↗

bioRxiv2026

Multiple motor proteins regulate ALS-linked TDP-43 anterograde axonal transport

TDP-43 is an RNA-binding protein essential for RNA metabolism. Under physiological conditions, it predominantly resides in the nucleus but is also expressed in the cytoplasm, where it regulates mRNA trafficking and local translation. In nearly 97% of Amyotrophic Lateral Sclerosis (ALS) cases, TDP-43 undergoes nuclear depletion and cytoplasmic aggregation. While its nuclear functions are well characterized, its axonal roles remain poorly understood, despite axonal degeneration being a hallmark of ALS pathology. To address this gap, we investigated TDP-43 localization and transport dynamics in axons of H9-derived human neurons. We compared fluorescently labeled TDP-43 with three well-characterized axonal cargoes, Rab5, synaptophysin, and APP, and examined protein-protein interactions between TDP-43 and the axonal transport machinery. Our analyses revealed that TDP-43 exhibits active anterograde axonal transport and interacts with multiple kinesin motor proteins, including all three KIF5 isoforms, through the adaptor KLC1, and the synaptic vesicles motor KIF1A. This multi-motor engagement suggests a flexible transport system that ensures mRNA delivery to distal axons. In ALS, where TDP-43 accumulates abnormally in the cytoplasm, this flexibility may become compromised, with multiple transport mechanisms simultaneously affected. This could contribute to progressive accumulation of non-functional TDP-43 granules, disrupting mRNA trafficking and local translation. Our findings provide a foundation for understanding how physiological TDP-43 transport mechanisms may be impaired during disease, highlighting axonal TDP-43 transport pathways as potential therapeutic targets.

neuroscience↗

bioRxiv2025

The Alzheimer's-Associated SORL1 p.Y1816C Variant Impairs APP Sorting, Axonal Trafficking, and Neuronal Activity in iPSC-Derived Brain Models

BackgroundSORL1, encoding the sorting receptor SORLA, is now recognized as the fourth autosomal dominant Alzheimers disease (AD) gene. Loss of SORLA function is known to disrupt endosomal trafficking and enhance amyloidogenic APP processing, two key aspects of the onset and progression of AD. However, the pathogenic consequences of disrupted endolysosomal pathways, deregulated protein sorting, as well as the effects of specific SORL1 missense variants on human neuronal function, still remain understudied. MethodsOur investigations were performed using two complementary human iPSC-derived models: 2D NGN2-induced neurons and 3D cerebral organoids established from isogenic wild-type (WT), SORL1 p.Y1816C (KI) missense variant, and SORL1 knock-out (KO) cells. We analyzed SORLA maturation and ectodomain shedding, APP localization, and amyloid-{beta} secretion. Endosomal morphology and neuritic swellings were assessed via electron microscopy, while axonal transport of APP and Rab5+ endosomes was evaluated through live-cell imaging. Neuronal network activity was measured using multielectrode array recordings. ResultsOur results demonstrate that the p.Y1816C variant leads to impaired SORLA maturation and reduced shedding, without affecting neuronal or organoid differentiation. Notably, we show an ultrastructure of endosomes, including their content, and demonstrate that both KO and KI models exhibit early endosome enlargement, increased APP retention in endosomes, elevated A{beta}40/42 secretion, and amyloid-{beta} deposition in 3D organoids. Importantly, we identified previously uncharacterized functional consequences of abolished SORLA activity, including axonal swellings and significantly impaired transport of Rab5+ endosomes and APP, characterized by deregulated velocities, directionality of transport, and increased stalling. Additionally, we discovered that both KO and p.Y1816C KI neurons exhibit abnormal electrophysiological activity, including increased spontaneous firing, burst frequency, and network synchrony. ConclusionsOur study defines the mechanistic consequences of the SORL1 p.Y1816C variant and demonstrates its pathogenicity in human neurons. Importantly, we also identify novel roles for SORLA in maintaining axonal transport homeostasis and regulating neuronal excitability, expanding its functional relevance beyond endosomal APP processing. These findings reinforce the central role of endosomal trafficking disruption in AD and support the use of isogenic human models for evaluating AD risk variants.

neuroscience↗

bioRxiv2022

Familial Alzheimer disease mutation undermines axonal transportby enhancing dynactin recruitment to the APP motor assemblies

Experiments in flies, mice and humans suggest a significant role of impaired axonal transport in the pathogenesis of Alzheimers disease (AD), however, the underlying mechanisms remain unknown1,2. We report that the Swedish familial AD (FAD) mutation perturbs fast anterograde axonal transport of the amyloid precursor protein (APP) by altering directionality of its movement. APP thus spends more time in retrograde movement and accumulates in the soma. We found that the Swedish mutation enhances recruitment of dynactin 1 to the APP transport assemblies. Given that dynactin 1 activates the retrograde motor dynein3, this hampers physiological anterograde axonal transport of APP. We last show that the Swedish mutation perturbs also the axonal transport of early endosomes, which rely on the same molecular motors as APP. Our findings reveal extensive impairment of the axonal transport pathways by a FAD mutation, which reflects dysregulation of the cargo motor assemblies.

neuroscience↗

bioRxiv2022

Unraveling axonal mechanisms of traumatic brain injury

Axonal swellings (AS) are the neuropathological hallmark of axonal injury in several disorders from trauma to neurodegeneration. Current evidence proposes a role of perturbed Ca2+ homeostasis in AS formation, involving impaired axonal transport and focal distension of the axons. Mechanisms of AS formation, in particular moments following injury, however, remain unknown. Here we show that AS form independently from intra-axonal Ca2+ changes, which are required primarily for the persistence of AS in time. We further show that the majority of axonal proteins undergoing de/phosphorylation immediately following injury belong to the cytoskeleton. This correlates with an increase in the distance of the actin/spectrin periodic rings and with microtubule tracks remodeling within AS. Observed cytoskeletal rearrangements support axonal transport without major interruptions. Our results demonstrate that the earliest axonal response to injury consists in physiological adaptations of axonal structure to preserve function rather than in immediate pathological events signaling axonal destruction.

neuroscience↗