The role of autophagy in epileptogenesis and in epilepsy-induced neuronal alterations

The mechanism of mitochondrial autophagy regulating Clathrin-mediated endocytosis in epilepsy

OBJECTIVE

The objective of this study is to determine whether inhibition of mitophagy affects seizures through Clathrin-mediated endocytosis (CME).

METHODS

Pentylenetetrazol (PTZ) was intraperitoneally injected daily to establish a chronic PTZ-kindled seizure. The Western blot (WB) was used to compare the differences in Parkin protein expression between the epilepsy group and the control group. Immunofluorescence was used to detect the expression of MitoTracker and LysoTracker. Transferrin-Alexa488 (Tf-A488) was injected into the hippocampus of mice. We evaluated the effect of 3-methyladenine (3-MA) on epilepsy behavior through observation in PTZ-kindled models.

RESULTS

The methylated derivative of adenine, known as 3-MA, has been extensively utilized in the field of autophagy research. The transferrin protein is internalized from the extracellular environment into the intracellular space via the CME pathway. Tf-A488 uses a fluorescent marker to track CME. Western blot showed that the expression of Parkin was significantly increased in the PTZ-kindled model (p < 0.05), while 3-MA could reduce the expression (p < 0.05). The fluorescence uptake of MitoTracker and LysoTracker was increased in the primary cultured neurons induced by magnesium-free extracellular fluid (p < 0.05); the fluorescence uptake of Tf-A488 was significantly decreased in the 3-MA group compared with the control group (p < 0.05). Following hippocampal injection of Tf-A488, both the epilepsy group and the 3-MA group exhibited decreased fluorescence uptake, with a more pronounced effect observed in the 3-MA group. Inhibition of mitophagy by 3-MA from day 3 to day 9 progressively exacerbated seizure severity and shortened latency.

SIGNIFICANCE

It is speculated that the aggravation of seizures by 3-MA may be related to the failure to remove damaged mitochondria in time and effectively after inhibiting mitochondrial autophagy, affecting the vesicle endocytosis function of CME and increasing the susceptibility to epilepsy.

SUMMARY

Abnormal mitophagy was observed in a chronic pentylenetetrazol-induced seizure model and a Mg2+-free-induced spontaneous recurrent epileptiform discharge model. A fluorescent transferrin marker was utilized to track clathrin-mediated endocytosis. Using an autophagy inhibitor (3-methyladenine) on primary cultured neurons, we discovered that inhibition of autophagy led to a reduction in fluorescent transferrin uptake, while impairing clathrin-mediated endocytosis function mediated by mitophagy. Finally, we examined the effects of 3-methyladenine in an animal model of seizures showing that it exacerbated seizure severity. Ultimately, this study provides insights into potential mechanisms through which mitophagy regulates clathrin-mediated endocytosis in epilepsy.

A Mutual Nexus Between Epilepsy and α-Synuclein: A Puzzle Pathway

Alpha-synuclein (α-Syn) is a specific neuronal protein that regulates neurotransmitter release and trafficking of synaptic vesicles. Exosome-associated α-Syn which is specific to the central nervous system (CNS) is involved in the pathogenesis of epilepsy. Therefore, this review aimed to elucidate the possible link between α-Syn and epilepsy, and how it affects the pathophysiology of epilepsy. A neurodegenerative protein such as α-Syn is implicated in the pathogenesis of epilepsy. Evidence from preclinical and clinical studies revealed that upregulation of α-Syn induces progressive neuronal dysfunctions through induction of oxidative stress, neuroinflammation, and inhibition of autophagy in a vicious cycle with subsequent development of severe epilepsy. In addition, accumulation of α-Syn in epilepsy could be secondary to the different cellular alterations including oxidative stress, neuroinflammation, reduction of brain-derived neurotrophic factor (BDNF) and progranulin (PGN), and failure of the autophagy pathway. However, the mechanism of α-Syn-induced-epileptogenesis is not well elucidated. Therefore, α-Syn could be a secondary consequence of epilepsy. Preclinical and clinical studies are warranted to confirm this causal relationship.

The Possible Role of Brain-derived Neurotrophic Factor in Epilepsy

Epilepsy is a neurological disease characterized by repeated seizures. Despite of that the brain-derived neurotrophic factor (BDNF) is implicated in the pathogenesis of epileptogenesis and epilepsy, BDNF may have a neuroprotective effect against epilepsy. Thus, the goal of the present review was to highlight the protective and detrimental roles of BDNF in epilepsy. In this review, we also try to find the relation of BDNF with other signaling pathways and cellular processes including autophagy, mTOR pathway, progranulin (PGN), and α-Synuclein (α-Syn) which negatively and positively regulate BDNF/tyrosine kinase receptor B (TrkB) signaling pathway. Therefore, the assessment of BDNF levels in epilepsy should be related to other neuronal signaling pathways and types of epilepsy in both preclinical and clinical studies. In conclusion, there is a strong controversy concerning the potential role of BDNF in epilepsy. Therefore, preclinical, molecular, and clinical studies are warranted in this regard.

Autophagy and autophagy signaling in Epilepsy: possible role of autophagy activator

Autophagy is an explicit cellular process to deliver dissimilar cytoplasmic misfolded proteins, lipids and damaged organelles to the lysosomes for degradation and elimination. The mechanistic target of rapamycin (mTOR) is the main negative regulator of autophagy. The mTOR pathway is involved in regulating neurogenesis, synaptic plasticity, neuronal development and excitability. Exaggerated mTOR activity is associated with the development of temporal lobe epilepsy, genetic and acquired epilepsy, and experimental epilepsy. In particular, mTOR complex 1 (mTORC1) is mainly involved in epileptogenesis. The investigation of autophagy's involvement in epilepsy has recently been conducted, focusing on the critical role of rapamycin, an autophagy inducer, in reducing the severity of induced seizures in animal model studies. The induction of autophagy could be an innovative therapeutic strategy in managing epilepsy. Despite the protective role of autophagy against epileptogenesis and epilepsy, its role in status epilepticus (SE) is perplexing and might be beneficial or detrimental. Therefore, the present review aims to revise the possible role of autophagy in epilepsy.

Hippocampus protection from apoptosis by Baicalin in a LiCl-pilocarpine-induced rat status epilepticus model through autophagy activation

BACKGROUND

Autophagy is associated with hippocampal injury following status epilepticus (SE) and is considered a potential therapeutic mechanism. Baicalin, an emerging multitherapeutic drug, has shown neuroprotective effects in patients with nervous system diseases due to its antioxidant properties.

AIM

To investigate the potential role of autophagy in LiCl-pilocarpine-induced SE.

METHODS

The drugs were administered 30 min before SE. Nissl staining showed that Baicalin attenuated hippocampal injury and reduced neuronal death in the hippocampus. Western blotting and terminal deoxynucleotidyl transferase dUTP nick end labeling assay confirmed that Baicalin reversed the expression intensity of cleaved caspase-3 and apoptosis in hippocampal CA1 following SE. Fur-thermore, western blotting and immunofluorescence staining were used to measure the expression of autophagy markers (p62/SQSTM1, Beclin 1, and LC3) and apoptotic pathway markers (cleaved caspase-3 and Bcl-2).

RESULTS

Baicalin significantly upregulated autophagic activity and downregulated mitochondrial apoptotic pathway markers. Conversely, 3-methyladenine, a commonly used autophagy inhibitor, was simultaneously administered to inhibit the Baicalin-induced autophagy, abrogating the protective effect of Baicalin on the mitochondrial apoptotic level.

CONCLUSION

We illustrated that Baicalin-induced activation of autophagy alleviates apoptotic death and protects the hippocampus of SE rats.

Pharmacological modulation of autophagy for epilepsy therapy: opportunities and obstacles

Epilepsy (EP) is a long-term neurological disorder characterized by neuroinflammatory responses, neuronal apoptosis, imbalance between excitatory and inhibitory neurotransmitters, and oxidative stress in the brain. Autophagy is a process of cellular self-regulation to maintain normal physiological functions. Emerging evidence suggests that dysfunctional autophagy pathways in neurons are a potential mechanism underlying EP pathogenesis. In this review, we discuss current evidence and molecular mechanisms of autophagy dysregulation in EP and the probable function of autophagy in epileptogenesis. Moreover, we review the autophagy modulators reported for the treatment of EP models, and discuss the obstacles to, and opportunities for, the potential therapeutic applications of novel autophagy modulators as EP therapies. Teaser: Defective autophagy affects the onset and progression of epilepsy, and many anti-epileptic drugs have autophagy-modulating effects.

Molecular Biomarkers of Neuronal Injury in Epilepsy Shared with Neurodegenerative Diseases

In neurodegenerative diseases, changes in neuronal proteins in the cerebrospinal fluid and blood are viewed as potential biomarkers of the primary pathology in the central nervous system (CNS). Recent reports suggest, however, that level of neuronal proteins in fluids also alters in several types of epilepsy in various age groups, including children. With increasing evidence supporting clinical and sub-clinical seizures in Alzheimer's disease, Lewy body dementia, Parkinson's disease, and in other less common neurodegenerative conditions, these findings call into question the specificity of neuronal protein response to neurodegenerative process and urge analysis of the effects of concomitant epilepsy and other comorbidities. In this article, we revisit the evidence for alterations in neuronal proteins in the blood and cerebrospinal fluid associated with epilepsy with and without neurodegenerative diseases. We discuss shared and distinctive characteristics of changes in neuronal markers, review their neurobiological mechanisms, and consider the emerging opportunities and challenges for their future research and diagnostic use.

Neuroprotection impact of biochanin A against pentylenetetrazol-kindled mice: Targeting NLRP3 inflammasome/TXNIP pathway and autophagy modulation

Recurrent seizures characterize epilepsy, a complicated and multifaceted neurological disease. Several neurological alterations, such as cell death and the growth of gorse fibers, have been linked to epilepsy. The dentate gyrus of the hippocampus is particularly vulnerable to neuronal loss and abnormal neuroplastic changes in the pentylenetetrazol (PTZ) kindling model. Biochanin A has potent anti-inflammatory and antioxidant properties, according to previous evidence and its possible impact in epilepsy has never previously been claimed. The current work aimed to investigate biochanin A's anti-epileptic potential in PTZ-induced kindling model in mice. Chronic epilepsy was established in mice by giving PTZ (35 mg/kg, i.p) every other day for 21 days. Biochanin A (20 mg/kg) was given daily till the end of the experiment. Biochanin A pretreatment significantly reduced the severity of epileptogenesis by 51.7% and downregulated the histological changes in the CA3 region of the hippocampus by 42% along with displaying antioxidant/anti-inflammatory efficacy through upregulated hemeoxygenase-1 (HO-1) and, erythroid 2-related factor 2 (Nrf2) levels in the brain by 1.9-fold and 2-fold respectively, parallel to reduction of malondialdehyde (MDA), myeloperoxidase (MPO), glial fibrillary acidic protein (GFAP) and L-glutamate/IL-1β/TXNIB/NLRP3 axis. Moreover, biochanin A suppressed neuronal damage by reducing the astrocytes' activation and significantly attenuated the PTZ-induced increase in LC3 levels by 55.5%. Furthermore, molecular docking findings revealed that BIOCHANIN A has a higher affinity for phosphoinositide 3-kinase (PI3k), threonine kinase2 (AKT2), and mammalian target of rapamycin complex 1 (mTORC1) indicating the neuroprotective and anti-epileptic characteristics of biochanin A in the brain tissue of PTZ-kindled mice.

Noradrenaline and Seizures: A Perspective on the Role of Adrenergic Receptors in Limbic Seizures

BACKGROUND

Noradrenergic fibers originating from the locus coeruleus densely innervate limbic structures, including the piriform cortex, which is the limbic structure with the lowest seizure threshold. Noradrenaline (NA) modulates limbic seizures while stimulating autophagy through β2- adrenergic receptors (AR). Since autophagy is related to seizure threshold, this perspective questions whether modulating β2-AR focally within the anterior piriform cortex affects limbic seizures.

OBJECTIVE

In this perspective, we analyzed a potential role for β2-AR as an anticonvulsant target within the anterior piriform cortex, area tempestas (AT).

METHODS

We developed this perspective based on current literature on the role of NA in limbic seizures and autophagy. The perspective is also grounded on preliminary data obtained by microinfusing within AT either a β2-AR agonist (salbutamol) or a β2-AR antagonist (butoxamine) 5 minutes before bicuculline.

RESULTS

β2-AR stimulation fully prevents limbic seizures induced by bicuculline micro-infusion in AT. Conversely, antagonism at β2-AR worsens bicuculline-induced seizure severity and prolongs seizure duration, leading to self-sustaining status epilepticus. These data indicate a specific role for β2-AR as an anticonvulsant in AT.

CONCLUSION

NA counteracts limbic seizures. This relies on various receptors in different brain areas. The anterior piriform cortex plays a key role in patients affected by limbic epilepsy. The anticonvulsant effects of NA through β2-AR may be related to the stimulation of the autophagy pathway. Recent literature and present data draw a perspective where β2-AR stimulation while stimulating autophagy mitigates limbic seizures, focally within AT. The mechanism linking β2-AR to autophagy and seizure modulation should be extensively investigated.

3BDO Alleviates Seizures and Improves Cognitive Function by Regulating Autophagy in Pentylenetetrazol (PTZ)-Kindled Epileptic Mice Model

3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3 H)-one (3BDO) is a mTOR agonist that inhibits autophagy. The main purpose of this study is to investigate the effects of 3BDO on seizure and cognitive function by autophagy regulation in pentylenetetrazol (PTZ)-kindled epileptic mice model. The PTZ-kindled epileptic mice model was used in study. The behavioral changes and electroencephalogram (EEG) of the mice in each group were observed. The cognitive functions were tested by Morris water maze test. The loss of hippocampal neurons was detected by hematoxylin-eosin (HE) staining and immunofluorescence analysis. Immunohistochemistry, western blot and q-PCR were employed to detect the expression of autophagy-related proteins and mTOR in the hippocampus and cortex. Less seizures, increased hippocampal neurons and reduced astrocytes of hippocampus were observed in the 3BDO-treated epileptic mice than in the PTZ-kindled epileptic mice. Morris water maze test results showed that 3BDO significantly improved the cognitive function of the PTZ-kindled epileptic mice. Western blot analyses and q-PCR revealed that 3BDO inhibited the expression of LC3, Beclin-1, Atg5, Atg7 and p-ULK1/ULK1, but increased that of p-mTOR/mTOR, p-P70S6K/P70S6K in the hippocampus and temporal lobe cortex of epileptic mice. Immunohistochemistry and immunofluorescence also showed 3BDO inhibited the LC3 expression and increased the mTOR expression in the hippocampus of epileptic mice. In addition, the autophagy activator EN6 reversed the decrease in the 3BDO-induced autophagy and aggravated the seizures and cognitive dysfunction in the epileptic mice. 3BDO regulates autophagy by activating the mTOR signaling pathway in PTZ-kindled epileptic mice model, thereby alleviating hippocampus neuronal loss and astrocytes proliferation, reducing seizures and effectively improving cognitive function. Therefore, 3BDO may have potential value in the treatment of epilepsy.

Molecular Mechanism and Regulation of Autophagy and Its Potential Role in Epilepsy

Autophagy is an evolutionally conserved degradation mechanism for maintaining cell homeostasis whereby cytoplasmic components are wrapped in autophagosomes and subsequently delivered to lysosomes for degradation. This process requires the concerted actions of multiple autophagy-related proteins and accessory regulators. In neurons, autophagy is dynamically regulated in different compartments including soma, axons, and dendrites. It determines the turnover of selected materials in a spatiotemporal control manner, which facilitates the formation of specialized neuronal functions. It is not surprising, therefore, that dysfunctional autophagy occurs in epilepsy, mainly caused by an imbalance between excitation and inhibition in the brain. In recent years, much attention has been focused on how autophagy may cause the development of epilepsy. In this article, we overview the historical landmarks and distinct types of autophagy, recent progress in the core machinery and regulation of autophagy, and biological roles of autophagy in homeostatic maintenance of neuronal structures and functions, with a particular focus on synaptic plasticity. We also discuss the relevance of autophagy mechanisms to the pathophysiology of epileptogenesis.

Dynorphin/KOR inhibits neuronal autophagy by activating mTOR signaling pathway to prevent acute seizure epilepsy

In previous studies, we found that dynorphin exerts antiepileptic effect by activating the kappa opioid receptor (KOR). However, the role of neuronal autophagy in dynorphin/KOR-mediated antiepileptic is still unclear. This study aimed to investigate the molecular mechanism of dynorphin's antiepileptic effect by inhibiting autophagy and reducing neuronal apoptosis. Here, a pilocarpine-induced rat model of epilepsy was established and hippocampal neurons were treated with Mg²⁺ -free exposed for epileptiform activity induction. The real-time polymerase chain reaction and Western blot analysis were used to evaluate messenger RNA and protein expression. The TdT-mediated dUTP-biotin nick end labeling staining and flow cytometry were used to analyze cell apoptosis in vivo and in vitro. Neuron cells viability was detected by Cell Counting Kit-8 assay. Immunofluorescent staining and green fluorescent protein-light chain 3 immunofluorescence were used to measure autophagy in vivo and in vitro. Results showed that overexpression of prodynorphin alleviated neuronal apoptosis, activated the mammalian target of rapamycin (mTOR) signaling pathway, and inhibited neuronal autophagy in epileptic rats. Dynorphin inhibited Mg²⁺ -free-induced seizure-like neuron apoptosis, partially reversing the effect of Mg²⁺ -free on the mTOR signaling pathway and seizure-like neuron autophagy. Further, using rapamycin, we found that dynorphin inhibited Mg²⁺ -free-induced seizure-like neuron autophagy and apoptosis by activating the mTOR signaling pathway. In conclusion, dynorphin inhibits autophagy by activating the mTOR signaling pathway and has a protective effect on epilepsy acute seizure and epilepsy-induced brain injury.

Perspective on mTOR-dependent Protection in Status Epilepticus

BACKGROUND

The piriform cortex, known as area tempestas, has a high propensity to trigger limbic epileptic seizures. Recent studies on human patients indicate that a resection containing the piriform cortex produces a marked improvement in patients suffering from intractable limbic seizures. This calls for looking back at the pharmacological and anatomical data on area tempestas. Within the piriform cortex, status epilepticus can be induced by impairing the desensitization of AMPA receptors. The mechanistic target of rapamycin complex1 (mTORC1) is a promising candidate.

OBJECTIVE

The present perspective aims to link the novel role of the piriform cortex with recent evidence on the modulation of AMPA receptors under the influence of mTORC1. This is based on recent evidence and preliminary data, leading to the formulation of interaction between mTORC1 and AMPA receptors to mitigate the onset of long-lasting, self-sustaining, neurotoxic status epilepticus.

METHODS

The perspective grounds its method on recent literature along with the actual experimental procedure to elicit status epilepticus from the piriform cortex and the method to administer the mTORC1 inhibitor rapamycin to mitigate seizure expression and brain damage.

RESULTS

The available and present perspectives converge to show that rapamycin may disrupt the seizure circuitry initiated in the piriform cortex to mitigate seizure duration, severity, and brain damage.

CONCLUSION

The perspective provides a novel scenario to understand refractory epilepsy and selfsustaining status epilepticus. It is expected to provide a beneficial outcome in patients suffering from temporal lobe epilepsy.

Decanoic Acid Stimulates Autophagy in D. discoideum

Ketogenic diets, used in epilepsy treatment, are considered to work through reduced glucose and ketone generation to regulate a range of cellular process including autophagy induction. Recent studies into the medium-chain triglyceride (MCT) ketogenic diet have suggested that medium-chain fatty acids (MCFAs) provided in the diet, decanoic acid and octanoic acid, cause specific therapeutic effects independent of glucose reduction, although a role in autophagy has not been investigated. Both autophagy and MCFAs have been widely studied in Dictyostelium, with findings providing important advances in the study of autophagy-related pathologies such as neurodegenerative diseases. Here, we utilize this model to analyze a role for MCFAs in regulating autophagy. We show that treatment with decanoic acid but not octanoic acid induces autophagosome formation and modulates autophagic flux in high glucose conditions. To investigate this effect, decanoic acid, but not octanoic acid, was found to induce the expression of autophagy-inducing proteins (Atg1 and Atg8), providing a mechanism for this effect. Finally, we demonstrate a range of related fatty acid derivatives with seizure control activity, 4BCCA, 4EOA, and Epilim (valproic acid), also function to induce autophagosome formation in this model. Thus, our data suggest that decanoic acid and related compounds may provide a less-restrictive therapeutic approach to activate autophagy.

Truncated Neogenin Promotes Hippocampal Neuronal Death after Acute Seizure

Protecting hippocampal neurons from death after seizure activity is critical to prevent an alteration of neuronal circuitry and hippocampal function. Here, we present a novel target, a truncated form of neogenin that is associated with seizure-induced hippocampal necroptosis, and novel use of the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) as a pharmacological regulator of neogenin truncation. We show that 3 days after pilocarpine-induced status epilepticus in mice, when hippocampal cell death is detected, the level of truncated neogenin is increased, while that of full-length neogenin is decreased. Moreover, phosphorylation of mixed lineage kinase domain-like pseudokinase, a crucial marker of necroptosis, was also markedly upregulated at 3 days post-status epilepticus. In cultured hippocampal cells, kainic acid treatment significantly reduced the expression of full-length neogenin. Notably, treatment with DAPT prevented neogenin truncation and protected cultured neurons from N-methyl-D-aspartate (NMDA)-induced death. These data suggest that seizure-induced hippocampal necroptosis is associated with the generation of truncated neogenin, and that prevention of this by DAPT treatment can protect against NMDA-induced excitotoxicity.

Association between autophagy-related protein 5 gene polymorphisms and epilepsy in Chinese patients

Autophagy is a highly conserved degradative process that has been associated with a number of neurological diseases. Autophagy-related protein 5 (ATG5) is one of the key genes for the regulation of the autophagy pathway. In this study, we investigated the potential relationship between ATG5 gene polymorphisms and epilepsy in Han Chinese population. We enrolled 112 patients with epilepsy and 100 healthy controls and detected the genotypic and allelic data of 6 single nucleotide polymorphisms (SNPs) in ATG5 (rs2245214, rs510432, rs548234, rs573775, rs6568431 and rs6937876). The associations of 6 SNPs and epilepsy were evaluated. The results revealed the genotypes of overdominant of rs510432 between controls and patients showed significant differences (P_overdominant = 0.003). Subgroup analysis showed a highly significant association of rs510432 with late-onset epilepsy (P_overdominant = 0.006), and rs548234 were associated with the susceptibility to temporal lobe epilepsy (P_codominant = 0.002, P_overdominant = 0.006). Furthermore, ATG5 was not linked to either early-onset epilepsy or drug-resistant epilepsy (p > 0.0083). These results demonstrated an association of an ATG5 gene variant with epilepsy, and stronger associations with several subgroups of epilepsy were identified. Our study may provide novel evidence for the role of ATG5 in epilepsy, and contribute to our understanding of the molecular mechanisms of this chronic neurological disease.

Trehalose Ameliorates Seizure Susceptibility in Lafora Disease Mouse Models by Suppressing Neuroinflammation and Endoplasmic Reticulum Stress

Lafora disease (LD) is one of the progressive and fatal forms of a neurodegenerative disorder and is characterized by teenage-onset myoclonic seizures. Neuropathological changes in LD include the formation of abnormal glycogen as Lafora bodies, gliosis, and neuroinflammation. LD is caused by defects in the gene coding for phosphatase (laforin) or ubiquitin ligase (malin). Mouse models of LD, developed by targeted disruption of these two genes, develop most symptoms of LD and show increased susceptibility to induced seizures. Studies on mouse models also suggest that defective autophagy might contribute to LD etiology. In an attempt to understand the specific role of autophagy in LD pathogenesis, in this study, we fed LD animals with trehalose, an inducer of autophagy, for 3 months and looked at its effect on the neuropathology and seizure susceptibility. We demonstrate here that trehalose ameliorates gliosis, neuroinflammation, and endoplasmic reticulum stress and reduces susceptibility to induced seizures in LD animals. However, trehalose did not affect the formation of Lafora bodies, suggesting the epileptic phenotype in LD could be either secondary to or independent of Lafora bodies. Taken together, our results suggest that autophagy inducers can be considered as potential therapeutic molecules for Lafora disease.

West Syndrome Caused By a Chloride/Proton Exchange-Uncoupling CLCN6 Mutation Related to Autophagic-Lysosomal Dysfunction

Vesicular chloride/proton exchangers of the CLC family are critically involved in the function of the endosomal-lysosomal pathway. Their dysfunction leads to severe disorders including intellectual disability and epilepsy for ClC-4, Dent's disease for ClC-5, and lysosomal storage disease and osteopetrosis for ClC-7. Here, we report a de novo variant p.Glu200Ala (p.E200A; c.599A>C) of the late endosomal ClC-6, encoded by CLCN6, in a patient with West syndrome (WS), severe developmental delay, autism, movement disorder, microcephaly, facial dysmorphism, and visual impairment. Mutation of this conserved glutamate uncouples chloride transport from proton antiport by ClC-6. This affects organellar ion homeostasis and was shown to be deleterious for other CLCs. In this study, we found that upon heterologous expression, the ClC-6 E200A variant caused autophagosome accumulation and impaired the clearance of autophagosomes by blocking autophagosome-lysosome fusion. Our study provides clinical and functional support for an association between CLCN6 variants and WS. Our findings also provide novel insights into the molecular mechanisms underlying the pathogenesis of WS, suggesting an involvement of autophagic-lysosomal dysfunction.

Pentraxin 3 Promotes Glioblastoma Progression by Negative Regulating Cells Autophagy

Glioblastoma is the most malignancy tumor generated from the central nervous system along with median survival time less than 14.6 months. Pentraxin 3 has been proved its association with patients’ poor survival outcome in various tumor. Recently, several studies revealed its association with glioblastoma progression but the mechanism is remained unknown. Autophagy is a programmed cells death and acts critical role in tumor progression. In this study, pentraxin 3 is recognized as prognostic prediction biomarker of glioblastoma and can promote glioblastoma progression through negative modulating tumor cells autophagy. Transcription factor JUN is assumed to participate in cells autophagy modulation by regulating pentraxin 3 expression. This work reveals novel mechanism of pentraxin 3 mediated glioblastoma progression. Furthermore, JUN is identified as potential transcription factor involves in pentraxin 3 mediated tumor cells autophagy.

Emerging Role of the Autophagy/Lysosomal Degradative Pathway in Neurodevelopmental Disorders With Epilepsy

Autophagy is a highly conserved degradative process that conveys dysfunctional proteins, lipids, and organelles to lysosomes for degradation. The post-mitotic nature, complex and highly polarized morphology, and high degree of specialization of neurons make an efficient autophagy essential for their homeostasis and survival. Dysfunctional autophagy occurs in aging and neurodegenerative diseases, and autophagy at synaptic sites seems to play a crucial role in neurodegeneration. Moreover, a role of autophagy is emerging for neural development, synaptogenesis, and the establishment of a correct connectivity. Thus, it is not surprising that defective autophagy has been demonstrated in a spectrum of neurodevelopmental disorders, often associated with early-onset epilepsy. Here, we discuss the multiple roles of autophagy in neurons and the recent experimental evidence linking neurodevelopmental disorders with epilepsy to genes coding for autophagic/lysosomal system-related proteins and envisage possible pathophysiological mechanisms ranging from synaptic dysfunction to neuronal death.

mTOR-Related Cell-Clearing Systems in Epileptic Seizures, an Update

Recent evidence suggests that autophagy impairment is implicated in the epileptogenic mechanisms downstream of mTOR hyperactivation. This holds true for a variety of genetic and acquired epileptic syndromes besides malformations of cortical development which are classically known as mTORopathies. Autophagy suppression is sufficient to induce epilepsy in experimental models, while rescuing autophagy prevents epileptogenesis, improves behavioral alterations, and provides neuroprotection in seizure-induced neuronal damage. The implication of autophagy in epileptogenesis and maturation phenomena related to seizure activity is supported by evidence indicating that autophagy is involved in the molecular mechanisms which are implicated in epilepsy. In general, mTOR-dependent autophagy regulates the proliferation and migration of inter-/neuronal cortical progenitors, synapse development, vesicular release, synaptic plasticity, and importantly, synaptic clustering of GABA_A receptors and subsequent excitatory/inhibitory balance in the brain. Similar to autophagy, the ubiquitin–proteasome system is regulated downstream of mTOR, and it is implicated in epileptogenesis. Thus, mTOR-dependent cell-clearing systems are now taking center stage in the field of epilepsy. In the present review, we discuss such evidence in a variety of seizure-related disorders and models. This is expected to provide a deeper insight into the molecular mechanisms underlying seizure activity.

FAM134B Attenuates Seizure-Induced Apoptosis and Endoplasmic Reticulum Stress in Hippocampal Neurons by Promoting Autophagy

Autophagy plays a critical role in epileptic neuronal injury, and recent studies have demonstrated that FAM134B plays an important role in regulating autophagy. However, the effect of FAM134B on epileptic neuronal injury remains unclear. In this study, we investigated the role of FAM134B in neuronal apoptosis and endoplasmic reticulum (ER) stress using the hippocampal neuronal culture model of acquired epilepsy (AE) in vitro. We found that in this model, the level of autophagy significantly increased, indicated by an elevated LC3-II/LC3-I ratio. FAM134B overexpression using lentiviral vectors enhanced autophagy, whereas FAM134B downregulation using lentiviral vectors impaired this process. In addition, the ER Ca²⁺ concentration was decreased and the intracellular level of reactive oxygen species was increased in this model. FAM134B overexpression was sufficient to reverse these changes. Moreover, FAM134B overexpression attenuated ER stress as shown by a decrease in the expression of C/-EBP homologous protein and glucose-regulated protein 78, and neuronal apoptosis induced by seizure, while FAM134B downregulation caused the opposite effects. Further, pre-treatment with the selective autophagy inhibitor 3-methyladenine abolished the effects of FAM134B on ER stress and neuronal apoptosis. Altogether, we demonstrate that FAM134B is an important regulator of AE-induced ER stress and neuronal apoptosis by controlling autophagy function.

High mobility group box 1 antibody represses autophagy and alleviates hippocampus damage in pilocarpine-induced mouse epilepsy model

As a neurological disorder, epilepsy has affected over 65 million people all over the world because of the unforeseeable seizures it might cause. However, in-depth understandings of the pathogenesis of epilepsy and effective treatments for the disease are still lacked. Recent discoveries suggest that autophagy, as an endogenous self-cleansing pathway in mammals, might be involved in the onset of epilepsy. Our study assumes that a non-histone DNA binding protein, high mobility group box-1 (HMGB1), formerly considered as a crucial inflammatory factor, may mediate the autophagy of neurons in epileptic mouse brain. To verify this hypothesis, pilocarpine induced epilepsy mouse model was constructed. The mice were treated with HMGB1 antibody for 4 weeks after the initial epileptic seizure. Behavioral test results suggested a recovery of learning ability and memory in epileptic mice when treated with HMGB1 antibody. Pathological changes in hippocampus were inspected under microscopes and hippocampus damages caused by seizures in mouse with epilepsy such as increased intracellular space were alleviated by HMGB1 antibody treatment. Moreover, the expressions of the proteins involved in autophagy pathways were detected by immunofluorescence staining and western blot. microtubule-associated protein 1A/1B-light chain 3 (LC3), Beclin 1, autophagy protein-5 (ATG5), and ATG7 levels were significantly decreased by HMGB1 antibody while the level of p62 was increased. TdT-mediated dUTP Nick-End Labeling (TUNEL) illustrated that cell apoptosis induced by seizures in hippocampus was mitigated by HMGB1 antibody. In conclusion, we propose that HMGB1 may induce increased autophagy in epilepsy mouse model.

CB2R orchestrates neuronal autophagy through regulation of the mTOR signaling pathway in the hippocampus of developing rats with status epilepticus

Neuronal loss and gliosis are the major pathological changes after status epilepticus (SE). The authors' previous study revealed the time-dependent changes of cannabinoid receptor type 2 (CB2R) in hippocampal neurons of developing rats after SE, which were accompanied by a decrease in the number of neurons. Meanwhile, growing evidence indicates that CB2R stimulation exerts anti-convulsant properties in seizure models. However, the activation of CB2R in neuronal repair in response to the damage after SE is still unclear. In this experiment, a highly-selective CB2R agonist JWH133 and antagonist AM630 were administered to determine the activity of CB2R in neuronal autophagy and apoptosis of the post-SE repair in developing rats. The present results revealed that activation of CB2R by JWH133, not only obviously lowered the success rate, 24-h death rate and the Racine stage in the model, but also extended the latency period to SE. In addition, compared with the vehicle control group, CB2R activation increased neuronal autophagy and the expression of phosphorylated-mammalian target of rapamycin (p-mTOR)/mTOR, Beclin-1, and LC3II/LC3I while decreasing the expression of p-Unc-51-like autophagy-activating kinase 1 (ULK-1)/ULK1, p62, and cleaved caspase-3. These results were dose-dependent and were especially evident in the high-dose group, and interestingly the opposite results were obtained in the AM630 group. Thus, CB2R orchestrates neuronal autophagy through regulation of the mTOR signaling pathway in the hippocampus of developing rats with SE. These findings might provide an important basis for further investigation of the therapeutic role of CB2R in ameliorating epilepsy-related neuronal damage.

Cell Clearing Systems Bridging Neuro-Immunity and Synaptic Plasticity

In recent years, functional interconnections emerged between synaptic transmission, inflammatory/immune mediators, and central nervous system (CNS) (patho)-physiology. Such interconnections rose up to a level that involves synaptic plasticity, both concerning its molecular mechanisms and the clinical outcomes related to its behavioral abnormalities. Within this context, synaptic plasticity, apart from being modulated by classic CNS molecules, is strongly affected by the immune system, and vice versa. This is not surprising, given the common molecular pathways that operate at the cross-road between the CNS and immune system. When searching for a common pathway bridging neuro-immune and synaptic dysregulations, the two major cell-clearing cell clearing systems, namely the ubiquitin proteasome system (UPS) and autophagy, take center stage. In fact, just like is happening for the turnover of key proteins involved in neurotransmitter release, antigen processing within both peripheral and CNS-resident antigen presenting cells is carried out by UPS and autophagy. Recent evidence unravelling the functional cross-talk between the cell-clearing pathways challenged the traditional concept of autophagy and UPS as independent systems. In fact, autophagy and UPS are simultaneously affected in a variety of CNS disorders where synaptic and inflammatory/immune alterations concur. In this review, we discuss the role of autophagy and UPS in bridging synaptic plasticity with neuro-immunity, while posing a special emphasis on their interactions, which may be key to defining the role of immunity in synaptic plasticity in health and disease.

Beta-propeller protein-associated neurodegeneration (BPAN) as a genetically simple model of multifaceted neuropathology resulting from defects in autophagy

Autophagy is an essential and conserved cellular homeostatic process. Defects in the core and accessory components of the autophagic machinery would most severely impact terminally differentiated cells, such as neurons. The neurodevelopmental/neurodegenerative disorder β-propeller protein-associated neurodegeneration (BPAN) resulted from heterozygous or hemizygous germline mutations/pathogenic variant of the X chromosome geneWDR45, encoding WD40 repeat protein interacting with phosphoinositides 4 (WIPI4). This most recently identified subtype of the spectrum of neurodegeneration with brain iron accumulation diseases is characterized by a biphasic mode of disease manifestation and progression. The first phase involves early-onset of epileptic seizures, global developmental delay, intellectual disability and autistic syndrome. Subsequently, Parkinsonism and dystonia, as well as dementia, emerge in a subacute manner in adolescence or early adulthood. BPAN disease phenotypes are thus complex and linked to a wide range of other neuropathological disorders. WIPI4/WDR45 has an essential role in autophagy, acting as a phosphatidylinositol 3-phosphate binding effector that participates in autophagosome biogenesis and size control. Here, we discuss recent updates on WIPI4’s mechanistic role in autophagy and link the neuropathological manifestations of BPAN’s biphasic infantile onset (epilepsy, autism) and adolescent onset (dystonic, Parkinsonism, dementia) phenotypes to neurological consequences of autophagy impairment that are now known or emerging in many other neurodevelopmental and neurodegenerative disorders. As monogenicWDR45mutations in BPAN result in a large spectrum of disease phenotypes that stem from autophagic dysfunctions, it could potentially serve as a simple and unique genetic model to investigate disease pathology and therapeutics for a wider range of neuropathological conditions with autophagy defects.

New insights into a spectrum of developmental malformations related to mTOR dysregulations: challenges and perspectives

In recent years the role of the mammalian target of rapamycin (mTOR) pathway has emerged as crucial for normal cortical development. Therefore, it is not surprising that aberrant activation of mTOR is associated with developmental malformations and epileptogenesis. A broad spectrum of malformations of cortical development, such as focal cortical dysplasia (FCD) and tuberous sclerosis complex (TSC), have been linked to either germline or somatic mutations in mTOR pathway-related genes, commonly summarised under the umbrella term 'mTORopathies'. However, there are still a number of unanswered questions regarding the involvement of mTOR in the pathophysiology of these abnormalities. Therefore, a monogenetic disease, such as TSC, can be more easily applied as a model to study the mechanisms of epileptogenesis and identify potential new targets of therapy. Developmental neuropathology and genetics demonstrate that FCD IIb and hemimegalencephaly are the same diseases. Constitutive activation of mTOR signalling represents a shared pathogenic mechanism in a group of developmental malformations that have histopathological and clinical features in common, such as epilepsy, autism and other comorbidities. We seek to understand the effect of mTOR dysregulation in a developing cortex with the propensity to generate seizures as well as the aftermath of the surrounding environment, including the white matter.

Therapeutic potential of endothelial progenitor cells in a rat model of epilepsy: Role of autophagy

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This is the first report showing EPCs therapeutic effects in PTZ-induced epilepsy.

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Intravenously administered EPCs homed into the epileptic rat hippocampus.

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EPCs amend the memory and locomotor activity deficits related to epilepsy.

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EPCs ameliorate epilepsy-associated alterations in neurotransmitters and autophagy.

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EPCs mitigate concomitant histological and vascular anomalies.

Epilepsy is one of the most well-known neurological conditions worldwide. One-third of adult epileptic patients do not respond to antiepileptic drugs or surgical treatment and therefore suffer from the resistant type of epilepsy. Stem cells have been given substantial consideration in the field of epilepsy therapeutics. The implication of pathologic vascular response in sustained seizures and the eminent role of endothelial progenitor cells (EPCs) in maintaining vascular integrity tempted us to investigate the potential therapeutic effects of EPCs in a pentylenetetrazole (PTZ)-induced rat model of epilepsy. Modulation of autophagy, a process that enables neurons to maintain an equilibrium of synthesis, degradation and subsequent reprocessing of cellular components, has been targeted. Intravenously administered EPCs homed into the hippocampus and amended the deficits in memory and locomotor activity. The cells mitigated neurological damage and the associated histopathological alterations and boosted the expression of brain-derived neurotrophic factor. EPCs corrected the perturbations in neurotransmitter activity and enhanced the expression of the downregulated autophagy proteins light chain protein-3 (LC-3), beclin-1, and autophagy-related gene-7 (ATG-7). Generally, these effects were comparable to those achieved by the reference antiepileptic drug, valproic acid. In conclusion, EPCs may confer therapeutic effects against epilepsy and its associated behavioural and biochemical abnormalities at least in part via the upregulation of autophagy. The study warrants further research in experimental and clinical settings to verify the prospect of using EPCs as a valid therapeutic strategy in patients with epilepsy.

mTOR-Related Brain Dysfunctions in Neuropsychiatric Disorders

The mammalian target of rapamycin (mTOR) is an ubiquitously expressed serine-threonine kinase, which senses and integrates several intracellular and environmental cues to orchestrate major processes such as cell growth and metabolism. Altered mTOR signalling is associated with brain malformation and neurological disorders. Emerging evidence indicates that even subtle defects in the mTOR pathway may produce severe effects, which are evident as neurological and psychiatric disorders. On the other hand, administration of mTOR inhibitors may be beneficial for a variety of neuropsychiatric alterations encompassing neurodegeneration, brain tumors, brain ischemia, epilepsy, autism, mood disorders, drugs of abuse, and schizophrenia. mTOR has been widely implicated in synaptic plasticity and autophagy activation. This review addresses the role of mTOR-dependent autophagy dysfunction in a variety of neuropsychiatric disorders, to focus mainly on psychiatric syndromes including schizophrenia and drug addiction. For instance, amphetamines-induced addiction fairly overlaps with some neuropsychiatric disorders including neurodegeneration and schizophrenia. For this reason, in the present review, a special emphasis is placed on the role of mTOR on methamphetamine-induced brain alterations.

mTOR-Dependent Cell Proliferation in the Brain

The mammalian Target of Rapamycin (mTOR) is a molecular complex equipped with kinase activity which controls cell viability being key in the PI3K/PTEN/Akt pathway. mTOR acts by integrating a number of environmental stimuli to regulate cell growth, proliferation, autophagy, and protein synthesis. These effects are based on the modulation of different metabolic pathways. Upregulation of mTOR associates with various pathological conditions, such as obesity, neurodegeneration, and brain tumors. This is the case of high-grade gliomas with a high propensity to proliferation and tissue invasion. Glioblastoma Multiforme (GBM) is a WHO grade IV malignant, aggressive, and lethal glioma. To date, a few treatments are available although the outcome of GBM patients remains poor. Experimental and pathological findings suggest that mTOR upregulation plays a major role in determining an aggressive phenotype, thus determining relapse and chemoresistance. Among several activities, mTOR-induced autophagy suppression is key in GBM malignancy. In this article, we discuss recent evidence about mTOR signaling and its role in normal brain development and pathological conditions, with a special emphasis on its role in GBM.

Autophagy-related protein expression was associated with BRAF V600E mutation in epilepsy associated glioneuronal tumors

PURPOSE

The aim of this study was to explore the expression level of autophagy-related proteins in epileptic patients with glioneuronal tumors (GNTs) and evaluate the association with clinicopathological features.

MATERIALS AND METHODS

We obtained the brain specimens from 33 patients with GNTs, including 22 gangliogliomas (GGs) and 11 dysembryoplastic neuroepithelial tumors (DNTs). The expression of two autophagy-related proteins (LC3B and Beclin-1) was evaluated by immunohistochemistry, and BRAF V600E mutation was examined by DNA sequencing.

RESULTS

Among 33 epileptic patients with GNTs, the frequency of high expression of LC3B was 36.4% (12/33), and that of Beclin-1 was 39.4% (13/33). High expression of LC3B and Beclin-1 proteins was significantly associated with BRAF V600E mutation in GNTs (P=0.008; P=0.018), and LC3B overexpression was also correlated with temporal location of GNTs (P=0.002). In GGs alone, high expression of LC3B revealed significant correlation with BRAF V600E mutation and temporal location (P=0.020; P=0.015), while Beclin-1 showed no correlation with them (P>0.05). Furthermore, autophagy-related proteins did not show any association with other studied clinicopathological features, such as gender, age at seizure onset, epilepsy duration and postoperative seizure outcome.

CONCLUSIONS

Our observations demonstrated that impaired autophagy may be associated with BRAF V600E mutation. However, large sample studies with long-term follow-up were required.

[Mitophagy and nervous system disease]

Mitophagy is a process during which the cell selectively removes the mitochondria via the mechanism of autophagy. It is crucial to the functional completeness of the whole mitochondrial network and determines cell survival and death. On the one hand, the damaged mitochondria releases pro-apoptotic factors which induce cell apoptosis; on the other hand, the damaged mitochondria eliminates itself via autophagy, which helps to maintain cell viability. Mitophagy is of vital importance for the development and function of the nervous system. Neural cells rely on autophagy to control protein quality and eliminate the damaged mitochondria, and under normal circumstances, mitophagy can protect the neural cells. Mutations in genes related to mitophagy may cause the development and progression of neurodegenerative diseases. An understanding of the role of mitophagy in nervous system diseases may provide new theoretical bases for clinical treatment. This article reviews the research advances in the relationship between mitophagy and different types of nervous system diseases.

Pharmacological modulation of autophagy: therapeutic potential and persisting obstacles

Autophagy is central to the maintenance of organismal homeostasis in both physiological and pathological situations. Accordingly, alterations in autophagy have been linked to clinically relevant conditions as diverse as cancer, neurodegeneration and cardiac disorders. Throughout the past decade, autophagy has attracted considerable attention as a target for the development of novel therapeutics. However, such efforts have not yet generated clinically viable interventions. In this Review, we discuss the therapeutic potential of autophagy modulators, analyse the obstacles that have limited their development and propose strategies that may unlock the full therapeutic potential of autophagy modulation in the clinic.

Mitophagy in Refractory Temporal Lobe Epilepsy Patients with Hippocampal Sclerosis

This study aimed to determine if there is an association between mitophagy and refractory temporal lobe epilepsy (rTLE) with hippocampal sclerosis. During epilepsy surgery, we collected tissue samples from the hippocampi and temporal lobe cortexes of rTLE patients with hippocampal sclerosis (as diagnosed by a pathologist). Transmission electron microscopy (TEM) was used to study the ultrastructural features of the tissue. To probe for mitophagy, we used fluorescent immunolabeling to determine if mitochondrial and autophagosomal markers colocalized. Fourteen samples were examined. TEM results showed that early autophagosomes were present and mitochondria were impaired to different degrees in hippocampi. Immunofluorescent labeling showed colocalization of the autophagosome marker LC3B with the mitochondrial marker TOMM20 in hippocampi and temporal lobe cortexes, indicating the presence of mitophagy. Mitochondrial and autophagosomal marker colocalization was lower in hippocampus than in temporal lobe cortex (P < 0.001). Accumulation of autophagosomes and mitophagy activation are implicated in rTLE with hippocampal sclerosis. Aberrant accumulation of damaged mitochondria, especially in the hippocampus, can be attributed to defects in mitophagy, which may participate in epileptogenesis.

The Autophagoproteasome a Novel Cell Clearing Organelle in Baseline and Stimulated Conditions

Protein clearing pathways named autophagy (ATG) and ubiquitin proteasome (UP) control homeostasis within eukaryotic cells, while their dysfunction produces neurodegeneration. These pathways are viewed as distinct biochemical cascades occurring within specific cytosolic compartments owing pathway-specific enzymatic activity. Recent data strongly challenged the concept of two morphologically distinct and functionally segregated compartments. In fact, preliminary evidence suggests the convergence of these pathways to form a novel organelle named autophagoproteasome. This is characterized in the present study by using a cell line where, mTOR activity is upregulated and autophagy is suppressed. This was reversed dose-dependently by administering the mTOR inhibitor rapamycin. Thus, we could study autophagoproteasomes when autophagy was either suppressed or stimulated. The occurrence of autophagoproteasome was shown also in non-human cell lines. Ultrastructural morphometry, based on the stochiometric binding of immunogold particles allowed the quantitative evaluation of ATG and UP component within autophagoproteasomes. The number of autophagoproteasomes increases following mTOR inhibition. Similarly, mTOR inhibition produces overexpression of both LC3 and P20S particles. This is confirmed by the fact that the ratio of free vs. autophagosome-bound LC3 is similar to that measured for P20S, both in baseline conditions and following mTOR inhibition. Remarkably, within autophagoproteasomes there is a slight prevalence of ATG compared with UP components for low rapamycin doses, whereas for higher rapamycin doses UP increases more than ATG. While LC3 is widely present within cytosol, UP is strongly polarized within autophagoproteasomes. These fine details were evident at electron microscopy but could not be deciphered by using confocal microscopy. Despite its morphological novelty autophagoproteasomes appear in the natural site where clearing pathways (once believed to be anatomically segregated) co-exist and they are likely to interact at molecular level. In fact, LC3 and P20S co-immunoprecipitate, suggesting a specific binding and functional interplay, which may be altered by inhibiting mTOR. In summary, ATG and UP often represent two facets of a single organelle, in which unexpected amount of enzymatic activity should be available. Thus, autophagoproteasome may represent a sophisticated ultimate clearing apparatus.

Autophagy in acute brain injury

Autophagy is an evolutionarily ancient mechanism that ensures the lysosomal degradation of old, supernumerary or ectopic cytoplasmic entities. Most eukaryotic cells, including neurons, rely on proficient autophagic responses for the maintenance of homeostasis in response to stress. Accordingly, autophagy mediates neuroprotective effects following some forms of acute brain damage, including methamphetamine intoxication, spinal cord injury and subarachnoid haemorrhage. In some other circumstances, however, the autophagic machinery precipitates a peculiar form of cell death (known as autosis) that contributes to the aetiology of other types of acute brain damage, such as neonatal asphyxia. Here, we dissect the context-specific impact of autophagy on non-infectious acute brain injury, emphasizing the possible therapeutic application of pharmacological activators and inhibitors of this catabolic process for neuroprotection.

Molecular network of neuronal autophagy in the pathophysiology and treatment of depression

Major depressive disorder (MDD) is a complicated multifactorial induced disease, characterized by depressed mood, anhedonia, fatigue, and altered cognitive function. Recently, many studies have shown that antidepressants regulate autophagy. In fact, autophagy, a conserved lysosomal degradation pathway, is essential for the central nervous system. Dysregulation of autophagic pathways, such as the mammalian target of rapamycin (mTOR) signaling pathway and the beclin pathway, has been studied in neurodegenerative diseases. However, autophagy in MDD has not been fully studied. Here, we discuss whether the dysregulation of autophagy contributes to the pathophysiology and treatment of MDD and summarize the current evidence that shows the involvement of autophagy in MDD.