Biology subjects

Waites, C.

Publications and source records attributed to Waites, C..

6 recordsLinked to original sources

bioRxiv2025

Glucocorticoids regulate small extracellular vesicle (sEV) release via activation of nSMase2

Chronic stress, marked by prolonged elevation of glucocorticoid (GC) stress hormones, is a major risk factor for Alzheimers disease (AD) and accelerates AD pathology in mouse models. A key mechanism contributing to AD progression is the release of small extracellular vesicles (sEVs) carrying pathogenic proteins (e.g., tau, amyloid-beta) between brain regions, but the role of GCs in sEV biogenesis and release is unknown. Using total internal reflection fluorescence (TIRF) microscopy and the pH-sensitive marker mCh-CD63-pHluorin to visualize sEV release, we show that GCs stimulate sEV secretion in a neuronal cell line. This process requires the GTPase Rab27a and the enzyme neutral sphingomyelinase 2 (nSMase2), which catalyzes ceramide production and drives sEV formation. We further demonstrate that GCs promote sEV release by activating nSMase2 downstream of mitochondrial reactive oxygen species production and opening of the mitochondrial permeability transition pore (mPTP). These findings link GC-induced mitochondrial damage, specifically mPTP opening, to nSMase2 activation and enhanced sEV release by neuronal cells. SummaryThis study reveals a mechanism by which glucocorticoid stress hormones promote extracellular vesicle release from neuronal cells by activating the enzyme neutral sphingomyelinase 2. These findings provide a possible explanation for how stress accelerates the spread of Alzheimers pathology in the brain. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/680983v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1056e33org.highwire.dtl.DTLVardef@185dbecorg.highwire.dtl.DTLVardef@1296bf0org.highwire.dtl.DTLVardef@6d9086_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

APOE4 exacerbates glucocorticoid stress hormone-induced tau pathology via mitochondrial dysfunction

APOE4 is the leading genetic risk factor for Alzheimers disease, and chronic stress is a leading environmental risk factor. Studies suggest that APOE4 confers vulnerability to the behavioral and neuropathological effects of chronic stress, representing a potential mechanism by which this genetic variant accelerates Alzheimers onset and progression. Whether and how APOE4-mediated stress vulnerability manifests in neurons of the hippocampus, a brain region particularly susceptible to stress and Alzheimers pathology, remains unexplored. Using a combination of in vivo and in vitro experiments in humanized APOE4 and APOE3 knockin mice and primary hippocampal neurons from these animals, we investigate whether and how APOE4 confers sensitivity to glucocorticoids, the main stress hormones. We find that a major hallmark of stress/glucocorticoid-induced brain damage, tau pathology (i.e., tau accumulation, hyperphosphorylation, and spreading) is exacerbated in APOE4 versus APOE3 mice. Moreover, APOE4 animals exhibit underlying mitochondrial dysfunction and enhanced glucocorticoid receptor activation in the hippocampus, factors that likely contribute to tau pathogenesis in both the presence and absence of stress/glucocorticoids. Supporting this concept, we show that opening of the mitochondrial permeability transition pore drives mitochondrial dysfunction and tau pathology in APOE4 mice, and that pharmacological inhibition of pore opening is protective against ApoE4-mediated mitochondrial damage, tau phosphorylation and spreading, and downstream hippocampal synapse loss. These findings shed light on the mechanisms of stress vulnerability in APOE4 carriers and identify the mitochondrial permeability transition pore as a potential therapeutic target for ameliorating Alzheimers pathogenesis in this population.

neuroscience↗

bioRxiv2020

KIF13A mediates the activity-dependent transport of ESCRT-0 proteins in axons

Turnover of synaptic vesicle (SV) proteins is vital for the maintenance of healthy and functional synapses. SV protein turnover is driven by neuronal activity in an ESCRT (endosomal sorting complex required for transport)-dependent manner. Here, we characterize a critical step in this process: axonal transport of ESCRT-0 component Hrs, necessary for sorting proteins into the ESCRT pathway and recruiting downstream ESCRT machinery to catalyze multivesicular body (MVB) formation. We find that neuronal activity stimulates the formation of presynaptic endosomes and MVBs, as well as the motility of Hrs+ vesicles in axons and their delivery to SV pools. Hrs+ vesicles co-transport ESCRT-0 component STAM1 and comprise a subset of Rab5+ vesicles, likely representing pro-degradative early endosomes. Furthermore, we identify kinesin motor protein KIF13A as essential for the activity-dependent transport of Hrs to SV pools and the degradation of SV membrane proteins. Together, these data demonstrate a novel activity- and KIF13A-dependent mechanism for mobilizing axonal transport of ESCRT machinery to facilitate the degradation of SV membrane proteins.

neuroscience↗

bioRxiv2019

Activity-dependent nucleation of dynamic microtubules at presynaptic boutons is required for neurotransmission

Control of microtubule (MT) dynamics is critical for neuronal function. Whether MT nucleation is regulated at presynaptic boutons and influences overall presynaptic activity remains unknown. By visualizing MT dynamics at individual excitatory en passant boutons in axons of hippocampal neurons we found that MTs preferentially grow from presynaptic boutons as a result of {gamma}-tubulin and augmin-dependent nucleation. MT nucleation at boutons is promoted by neuronal activity, functionally coupled to synaptic vesicle (SV) transport, and required for neurotransmission. Hence, en passant boutons act as hotspots for activity-dependent MT nucleation, which is required for neurotransmission by providing the tracks for a rate-limiting supply of SVs to sites of neurotransmitter release.\n\nHighlightsO_LIExcitatory boutons are hotspots for neuronal activity-induced {gamma}-tubulin dependent MT nucleation\nC_LIO_LIThe augmin complex is required for the correct polarity of presynaptic de novo nucleated MTs\nC_LIO_LIPresynaptic MT nucleation promotes SV motility and exocytosis at sites of release\nC_LI\n\nIn BriefOur results demonstrate that excitatory en passant boutons are hotspots for neuronal activity-induced {gamma}-tubulin- and augmin-dependent oriented MT nucleation, and that the resulting presynaptic de novo nucleated MTs promote inter-bouton SV motility which is rate-limiting for neurotransmitter release.

cell biology↗

bioRxiv2018

Parkinson’s disease-linked Parkin mutations impair glutamatergic synaptic transmission and plasticity

Parkinson's disease (PD)-associated E3 ubiquitin ligase Parkin is enriched at glutamatergic synapses, where it ubiquitinates multiple substrates, suggesting that its mutation/loss-of-function could contribute to the etiology of PD by disrupting excitatory neurotransmission. Here, we evaluate the impact of four common PD-associated Parkin point mutations (T240M, R275W, R334C, G430D) on glutamatergic synaptic function in hippocampal neurons. We find that expression of these point mutants in Parkin-deficient and -null backgrounds alters NMDA and AMPA receptor-mediated currents and cell-surface levels, and prevents the induction of long-term depression. Mechanistically, we demonstrate that Parkin regulates NMDA receptor trafficking through its ubiquitination of GluN1, and that all four mutants are impaired in this ubiquitinating activity. Furthermore, Parkin regulates synaptic AMPA receptor trafficking via its binding and retention of postsynaptic scaffold Homer1, and all mutants are similarly impaired in this capacity. Our findings demonstrate that pathogenic Parkin mutations disrupt glutamatergic synaptic transmission and plasticity by impeding NMDA and AMPA receptor trafficking, and through these effects likely contribute to the pathophysiology of PD in PARK2 patients.

neuroscience↗

bioRxiv2018

Fine-scale excitatory cortical circuits reflect embryonic progenitor pools

Introductory paragraph Introductory paragraph Main text Animals In utero electroporation Intrathalamic injections Slice preparation and recording... Stimulation and recording... Analysis of recordings Histological analyses Statistics Methods Author Contributions References The mammalian neocortex is characterised by precise patterns of synaptic connections, which dictate how information flows through cortical circuits. The degree of convergence and divergence of excitatory information results from highly non-random, short-range and long-range glutamatergic synaptic connections1-11. Previous seminal work has shown that c ...

neuroscience↗