autophagy

Hepatotoxicity of Legacy and Replacement PFAS: Role of BRUCE-Mitochondrial Interactions

Epidemiological studies have shown a strong association between exposure to PFAS (Per- and Poly- fluoroalkyl Substances) and liver toxicity. Particularly, legacy C8-PFAS members, PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid), are highly toxic, with PFOS estimated to be approximately 10 times more toxic than PFOA in ecotoxicity models. Consequently, PFAS replacements such as GenX and PFBS are marketed as safe alternatives, although growing evidence indicates that these substitutes also exhibit toxic effects. Lab animal model studies have shown hepatotoxic effects of both legacy and replacement PFAS members, characterized by Metabolic dysfunction-associated steatotic liver disease (MASLD) and its severe form Metabolic dysfunction- associated steatohepatitis (MASH), the two chronic liver diseases affecting an estimated 80-100 million Americans. The broader objective of this project is to understand the underlying mechanisms of PFAS hepatotoxicity in MASLD/MASH. In this context, our initial studies have shown that PFAS exposure of mice downregulates hepatic BRUCE, an autophagy inhibitor, resulting in development of MASLD in WT, and more severe MASLD and even progression to MASH in BRUCE liver-knockdown (BKO) mice. Using primary hepatocytes, we found PFAS-induced BRUCE reduction compromised mitochondrial (mt) functions (respiration, fatty acid oxidation/FAO, and ATP production) and suppressed mitophagy in WT and more so in BKO mice. Pharmacological restoration of mt function in mice prevented PFAS-induced MASLD/MASH. Guided by these compelling preliminary data and scientific premise, we hypothesize that PFAS degradation of BRUCE in hepatocytes induces excessive autophagy (resulting in cytotoxicity) and inhibits mitophagy (resulting in accumulation of damaged mitochondria), leading to release of mtDAMPs to activate inflammation/ fibrosis, thereby facilitating progression from MASLD to MASH. We will test this by three specific aims. Aim 1 (ex vivo) is to determine the human-relevant PFAS doses that modulate BRUCE levels for homeostatic vs cytotoxic autophagy and how BRUCE in turn regulates autophagy. Aim 2 (ex vivo) will investigate BRUCE-driven mitophagy pathway specific to PFAS exposure at human-relevant doses. Aim 3 (ex vivo and in vivo) will involve ex vivo simulation experiments to characterize the role of PFAS-induced, BRUCE-dependent hepatocyte- released mt DAMPs in activation of immune and fibrogenic cells using co-culture assays. Next, we will perform in vivo intervention to validate the role of PFAS-damaged mitochondria in driving MASH progression in mouse models. Furthermore, human relevance of the delineated mechanisms will be ascertained and validated using iPSC-derived human liver organoid system. Impact: This project will advance our understanding of autophagy/mitophagy-centric mechanisms with therapeutic potential in the context of PFAS-induced liver disease MASLD/MASH.

A PROTAC Strategy to Combat Botulinum Neurotoxicity

PROJECT SUMMARY/ABSTRACT Botulinum neurotoxin (BoNT), the causative agent of botulism, is the most potent toxin known to humans. While BoNTs are widely recognized for their therapeutic and cosmetic applications, such as Botox™, their increasing use has raised concerns about iatrogenic botulism. Due to their extreme lethality, ease of production, and history of weaponization, the Centers for Disease Control and Prevention (CDC) classifies BoNTs as a Category A bioterrorism threat. Among the seven major serotypes (A-G), BoNT/A, BoNT/B, and BoNT/E account for over 95% of human botulism cases with A being the most prevalent. Despite the severity of botulism, no approved therapeutic exists to rescue intoxicated neurons. The current treatment, a heptavalent antitoxin, can only slow disease progression and requires early administration and prolonged hospitalization due to the inability of antibodies to penetrate infected cells. In the field of small- molecule inhibitors (SMIs), promising scaffolds targeting BoNT/A have been discovered, offering opportunities for further derivatization to incorporate bifunctional approaches. Developing a clinically viable therapeutic requires inhibiting the zinc (Zn2+) metalloprotease light chain (LC) as well as addressing toxin persistence. Through extensive inhibitor screening, we have identified two classes of small molecules that inhibit BoNT/A with submicromolar affinity and demonstrate efficacy in both cellular and animal models. However, the transient nature of these inhibitors necessitates the need of a sustained clearance approach. To achieve this, we propose integrating our previously identified BoNT/A LC SMIs with a targeted protein degradation (TPD) technology for toxin elimination. Based upon the background outlined, vide supra, our research strategy for the ablation of BoNT/A will be focused upon the following three specific objectives: 1) Structural Optimization – Utilize molecular docking, and structure-activity relationship (SAR) analysis to modify inhibitors for TPD ligand attachment. 2) Degrader Design – Development of ubiquitin-protease system (UPS)-based proteolysis-targeting chimeras (PROTACs) and autophagy-targeting chimeras to enhance degradation efficiency. 3) Cellular Evaluation – Assess enzyme inhibition, toxin clearance, degradation kinetics in cells.

‘Autophagy regulates neurotransmission by controlling the axonal endoplasmic reticulum’

How does a neuron decide when and where to make a synapse?

Precise synaptic connectivity is a prerequisite for the function of neural circuits, yet individual neurons, taken out of their developmental context, readily form unspecific synapses. How does genetically encoded brain wiring deal with this apparent contradiction? Brain wiring is a developmental growth process that is not only characterized by precision, but also flexibility and robustness. As in any other growth process, cellular interactions are restricted in space and time. Correspondingly, molecular and cellular interactions are restricted to those that 'get to see' each other during development. This seminar will explore the question how neurons decide when and where to make synapses using the Drosophila visual system as a model. New findings reveal that pattern formation during growth and the kinetics of live neuronal interactions restrict synapse formation and partner choice for neurons that are not otherwise prevented from making incorrect synapses in this system. For example, cell biological mechanisms like autophagy as well as developmental temperature restrict inappropriate partner choice through a process of kinetic exclusion that critically contributes to wiring specificity. The seminar will explore these and other neuronal strategies when and where to make synapses during developmental growth that contribute to precise, flexible and robust outcomes in brain wiring.

Neuronal autophagy promotes the hormonal regulation of brain cognitive and metabolic functions

Targeting selective autophagy against neurodegenerative diseases

Protein quality control is essential for maintenance of a healthy and functional proteome that can attend the multiplicity of cellular functions. Failure of the systems that contribute to protein homeostasis, the so called proteostasis networks, have been identified in the pathogenesis of multiple neurodegenerative disorders and demonstrated to contribute to disease onset and progression. We are interested in autophagy, one of the components of the proteostasis network, and in the interplay of wo selective types of autophagy, chaperone-mediated autophagy (CMA) and endosomal microautophagy (eMI), with neurodegeneration. We have recently found that pathogenic proteins involved in common neurodegenerative conditions such as tauopathies or Parkinson’s disease, can exert a toxic effect in both types of selective types of autophagy compromising their functioning. We have now used mouse models with compromised CMA that support increased propagation of proteins such as tau and alpha-synuclein and an exacerbation of disease phenotype with aging. Conversely, genetic or chemical upregulation of CMA in this context of proteotoxicity slow down disease progression by facilitating effective intracellular removal of pathogenic proteins. Our findings highlight CMA and eMI as potential novel therapeutic targets against neurodegeneration.

ATP6V1A, a key player for lysosomal function and autophagy process, is required for neuronal development and synaptic plasticity

Autophagy and ESCRT machinery impairment and lysosomal damage in frontal cortex and hippocampus of rats in a depression-like model

Autophagy and neurodevelopmental disorders 2 : Ultrasonic vocalization (USV) and social interaction from preweaning up to adult Irgm1-ko mice

Autophagy and neurodevelopmental disorders 1 : Sensory motor development in preweaning Irgm1-ko mice

Contribution of GBA1 mutations to autophagy-lysosomal pathway in Parkinson's disease

Identifying deregulated autophagy as underlying mechanism of neurodevelopmetnal disorders

Inhibition of Neuronal Autophagy Contributes to Reduced Ischemic Brain Damage in rats

Interplay between Lewy pathology and macroautophagy in midbrain dopaminergic neurons in vivo

Modulation of anandamide tone as an effective strategy for in vitro and in vivo stimulation of autophagy in Alzheimer's disease

The NMDA receptor triggers neuronal autophagy during Oxygen and Glucose Deprivation

Priming mesenchymal stem cells with α-synuclein enhances neuroprotective properties through induction of autophagy in Parkinsonian models

Regulation of the apoptosis/autophagy switch by propionic acid in ventromedial hypothalamus of rats with type 2 diabetes mellitus

Regulation of Neuronal Autophagy by Endocytic Kinase AAK1

The role of autophagy in parvalbumin-expressing neurons

Role of the neuronal primary cilia-autophagy axis in the regulation of cognition during aging

The Serum Response Factor (SRF) regulates motoneuron vulnerability in ALS through the regulation of autophagy flux

SIRT1-dependent autophagy as a novel therapy for age-related memory decline

TBC1D24 interacts with v-ATPase and regulates pH homeostasis and autophagy in neurons

Activation of non-nuclear estrogen receptor signaling pathways with PaPE-1 as a potential remedy for amyloid-beta induced toxicity: Impact on autophagy

FENS Forum 2024

Altered autophagy in KANSL1 haploinsufficient iPSC-derived astrocytes

FENS Forum 2024

Autophagy modulation of glial neuroinflammatory responses in Parkinson’s disease

FENS Forum 2024

Autophagy regulation during brain development and synaptogenesis

FENS Forum 2024

Chaperone mediated autophagy is deficient in spinal motoneurons of ALS patients

FENS Forum 2024

Dissecting the role of autophagy to elucidate the differential response of oligodendrocytes and astrocytes to hypoxic injury in vitro

FENS Forum 2024

Effect of melatonin on the autophagy in the prefrontal cortex of streptozotocin-induced type 1 diabetic rats

FENS Forum 2024

Identification of sex-specific autophagy enhancers for dementia

FENS Forum 2024

Impaired macroautophagy in oligodendrocyte precursor cells exacerbates aging-related cognitive deficits via a senescence-associated signaling

FENS Forum 2024

Infantile ceroid neuro-lipofuscinosis: Linking autophagy, altered chloride homeostasis, and enhanced brain excitability

FENS Forum 2024

Interplay between tubulin tyrosination, autophagy and neuron health

FENS Forum 2024

Longitudinal autophagy profiling of mammalian brain circuits reveals dynamic and sustained mitophagy throughout healthy aging

FENS Forum 2024

Neuroprotective effect of bicifadine, sertraline, and tiagabine with autophagy-inducing activity in 6-hydroxydopamine Parkinson’s models

FENS Forum 2024

A novel role for autophagy protein WIPI2 in cognitive fitness

FENS Forum 2024

Pharmacological stimulation of autophagy to rescue proteinopathy and cognitive decline in lysosomal storage disorders

FENS Forum 2024

Rab5-associated transcriptome reveals a new link between endosomes and autophagy in axons

FENS Forum 2024

Role of late endosomal autophagy-dependent secretion in neurodegeneration

FENS Forum 2024

The serine-threonine kinase Ndr2 impairs spatial memory and regulates autophagy and protein expression in the synapses of the ageing hippocampus

FENS Forum 2024

Testing the therapeutic effects of autophagy enhancement in a Rett syndrome mouse model

FENS Forum 2024

TFEB-loaded exosomes mediated autophagy induction in Alzheimer’s disease

FENS Forum 2024

Tibolone improves locomotor function in a rat model of spinal cord injury by modulating apoptosis and autophagy

FENS Forum 2024