Biology subjects

Stavoe, A. K.

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

8 recordsLinked to original sources

bioRxiv2026

Different forms of autophagy restrict neurite outgrowth in disparate compartments in a single neuron

Autophagy is a degradative pathway that is critical in neurons to maintain their homeostasis and to direct nervous system development. Neurons are large, highly polarized cells with distinct compartments that perform discrete functions. How an individual neuron can differentially mobilize autophagy in the axon, dendrite, and cell body is unknown. Here we interrogate the role of autophagy in the neurodevelopment of a single neuron in Caenorhabditis elegans to identify how the spatial compartmentalization of neuronal autophagy ultimately restricts neurite outgrowth in multiple neuronal compartments. However, while canonical autophagy restricts dendrite outgrowth, noncanonical forms of autophagy appear to restrain neurite outgrowth in the axon and soma. Through mutant analysis of the autophagy pathway, we identify that WIPI2-independent autophagy modulates ectopic neurite formation in the soma and that ATG9-independent autophagy regulates axon arborization. Further, we find that unrelated lipid scramblases can compensate for the loss of ATG9 in axon arborization. Our data indicate that neurons marshal both canonical and non-canonical autophagy to spatially control development of separate compartments.

neuroscience↗

bioRxiv2026

Endogenous autophagosome reporters reveal redundant and non-redundant roles of LGG-1 and LGG-2 in C. elegans neuronal autophagy

Autophagy is a conserved cellular recycling pathway essential for neuronal development and homeostasis. Neurons are highly polarized cells that rely on the continual turnover of cytoplasmic content through processes like autophagy to maintain cellular function. Here, we employed novel endogenous autophagosome reporters to define the distinct expression patterns, spatial distribution, and compensatory potential of the two C. elegans Atg8 orthologs, LGG-1 and LGG-2, in the nervous system. We labelled LGG-1 and LGG-2 with split wrmNeonGreen to endogenously label autophagosomes in individual neurons. We observed brighter and larger wrmNGsplit:LGG-1 autophagosomes relative to smaller and dimmer wrmNGsplit:LGG-2 autophagosomes pan-neuronally and in the individual AIY and NSM neurons. When we interrogated autophagosome trafficking in the AIY neurite, we revealed a similar trafficking mechanism for both LGG-1 and LGG-2 puncta. In AIY and pan-neuronally, we found that lgg-2 was required for LGG-1 puncta formation. Strikingly, in lgg-1 mutants, LGG-2 demonstrated a compensatory capacity in the AIY neuron via an upregulation of LGG-2 autophagosomes. Overall, our findings demonstrate the advantages of this novel endogenous reporter system for tracking neuronal autophagy and further elucidate redundant and non-redundant functions of LGG-1 and LGG-2.

cell biology↗

bioRxiv2026

PP2A and CDK16 antagonistically regulate WIPI2B phosphorylation and neuronal autophagosome biogenesis

Autophagy is a recycling pathway that clears cellular constituents, supporting homeostasis. In primary murine neurons, autophagosome biogenesis declines during aging. Importantly, this decline can be restored by the ectopic expression of key autophagy component WIPI2B. The phosphorylation state of WIPI2B serine 395 is critical for this restoration, suggesting that WIPI2B S395 phosphorylation regulates autophagosome biogenesis. Here, we identified protein phosphatase 2A (PP2A) and CDK16 as regulators of WIPI2B S395 phosphorylation and neuronal autophagy. Using Caenorhabditis elegans, we showed that PP2A and CDK16 regulate neuronal autophagy through the same genetic pathway as WIPI2B in vivo. Further, purified mammalian PP2A and CDK16 directly modified WIPI2B S395 phosphorylation in vitro. In primary murine neurons, PP2A and CDK16 colocalized with WIPI2B at autophagosomes, and manipulation of PP2A and CDK16 expression altered WIPI2B puncta formation and rates of autophagosome biogenesis. Altogether, our data support the conclusion that PP2A and CDK16 regulate WIPI2B S395 phosphorylation, modulating autophagosome biogenesis in neurons.

cell biology↗

bioRxiv2025

Sex does not Influence Neuronal Autophagy throughout Aging in Mice

Autophagy is critical for the homeostasis and function of neurons, as misregulation of autophagy has been implicated in age-related neurodegenerative diseases and neuron-specific knockdown of early autophagy genes results in early neurodegeneration in mice. We previously found that autophagosome formation decreases with age in murine neurons. Sex differences have been intensely studied in neurodegenerative diseases, but whether sex differences influence autophagy at the neuronal level have not been investigated. We compared protein expression of 22 autophagy components between neural tissues of female and male mice across development and aging. We found minimal sex-related differences in autophagy protein expression throughout the murine lifespan. Additionally, we assayed the recruitment of autophagy complexes and autophagosome biogenesis; we found no sex-dependent differences in multiple stages of autophagosome formation in neurons, independent of age. Our data suggest that biological sex does not influence autophagosome formation in neurons across development and aging.

cell biology↗

bioRxiv2022

Distinct adaptations revealed by unbiased proteomic analysis of autophagy cargos in the brain in PINK1 and LRRK2 models of Parkinson's disease

Autophagy is essential for neuronal homeostasis, while defects in autophagy are implicated in Parkinson disease (PD), a prevalent and progressive neurodegenerative disorder. We used unbiased proteomics to compare cargos degraded by basal autophagy in the brain from two mouse models of PD, PINK1-/- and LRRK2G2019S mice. We find evidence for the upregulation of adaptive pathways to support homeostasis in both PD models. In PINK1-/- mice, we observed increased expression of the selective receptor BNIP3 along with evidence of engagement of other alternative pathways for mitophagy. Despite these changes, we find the rate of autophagic flux in PINK1-/- neurons is decreased. In LRRK2G2019S mice, hyperactive kinase activity known to impair autophagosomal and lysosomal function results in increased secretion of extracellular vesicles and autophagy cargo. In support of this observation, we find reduced levels of PIKFYVE, a negative regulator of extracellular vesicle secretion, in both brain and cortical neurons from LRRK2G2019S mice. Thus, distinct adaptive pathways are activated to compensate for perturbations induced by either loss of PINK1 or hyperactivation of LRRK2. Our findings highlight the engagement of compensatory pathways to maintain homeostasis in the brain, and provide insights into the vulnerabilities these compensatory changes may introduce that may further contribute to PD progression.

molecular biology↗

bioRxiv2022

Aging Differentially Affects Axonal Autophagosome Formation and Maturation

Misregulation of neuronal autophagy has been implicated in age-related neurodegenerative diseases including Parkinsons disease and Huntingtons disease. We compared autophagosome formation and maturation in primary murine neurons during development and through aging to elucidate how aging affects neuronal autophagy. We observed an age-related decrease in the rate of formation of LC3B-positive autophagosomes leading to a significant decrease in the density of autophagosomes along the axon. Next, we assessed the maturation of autophagic vesicles and identified a surprising increase in their maturation in neurons from aged mice. While we did not detect notable changes in endolysosomal content in the distal axon during aging, we found that autophagic vesicles were transported more efficiently in neurons from adult mice than in neurons from young mice. This efficient transport of autophagic vesicles in both the distal and proximal axon is maintained in neurons from aged mice and indicates that aging alone does not impair transport nor negatively impact the later stages of autophagy. However, the pronounced deficit in autophagosome biogenesis in aged neurons may contribute to a decreased capacity to clear aggregated proteins or dysfunctional organelles and thus contribute to age-related degeneration.

neuroscience↗

bioRxiv2021

Structural Basis for Membrane Recruitment of ATG16L1 by WIPI2 in Autophagy

Autophagy is a cellular process that degrades cytoplasmic cargo by engulfing it in a double membrane vesicle, known as the autophagosome, and delivering it to the lysosome. The ATG12-5-16L1 complex is responsible for conjugating members of the ubiquitin-like ATG8 protein family to phosphatidylethanolamine in the growing autophagosomal membrane, known as the phagophore. ATG12-5-16L1 is recruited to the phagophore by a subset of the phosphatidylinositol 3-phosphate-binding seven bladed {beta}-propeller WIPI proteins. We determined the crystal structure of WIPI2d in complex with the WIPI2 interacting region (W2IR) of ATG16L1 comprising residues 207-230 at 1.85 [A] resolution. The structure shows that the ATG16L1 W2IR adopts an alpha helical conformation and binds in an electropositive and hydrophobic groove between WIPI2 {beta}-propeller blades 2 and 3. Mutation of residues at the interface reduces or blocks the recruitment of ATG12-5-16L1 and the conjugation of the ATG8 protein LC3B to synthetic membranes. Interface mutants show a decrease in starvation-induced autophagy. Comparisons across the four human WIPIs suggest that WIPI1 and 2 belong to a W2IR-binding subclass responsible for localizing ATG12-5-16L1 and driving ATG8 lipidation, whilst WIPI3 and 4 belong to a second W34IR-binding subclass responsible for localizing ATG2, and so directing lipid supply to the nascent phagophore. The structure provides a framework for understanding the regulatory node connecting two central events in autophagy initiation, the action of the autophagic PI 3-kinase complex on the one hand, and ATG8 lipidation on the other.

cell biology↗

bioRxiv2018

Expression of WIPI2B counteracts age-related decline in autophagosome biogenesis in neurons

Autophagy defects have been implicated in multiple late-onset neurodegenerative diseases. Since aging is the most common risk factor in neurodegeneration, we asked how autophagy is modulated in aging neurons. We compared the dynamics of autophagosome biogenesis in neurons from young adult and aged mice, identifying a significant decrease in biogenesis during aging. Autophagosome assembly kinetics are disrupted, with frequent production of stalled isolation membranes in neurons from aged mice; these precursors failed to resolve into LC3-positive autophagosomes. We did not detect alterations in the initial induction/nucleation steps of autophagosome formation. However, we found that the transmembrane protein Atg9 remained aberrantly associated with stalled isolation membranes, suggesting a specific disruption in the WIPI-dependent retrieval of Atg9. Depletion of WIPI2 from young neurons was sufficient to induce a similar deficit. Further, exogenous expression of WIPI2 in neurons from aged mice was sufficient to restore autophagosome biogenesis to the rates seen in neurons from young adult mice, suggesting a novel therapeutic target for age-associated neurodegeneration.

neuroscience↗