Suppression of basal autophagy in neural cells causes neurodegenerative disease in mice

Epidermal maintenance of Langerhans cells relies on autophagy-regulated lipid metabolism

Macroautophagy (often-named autophagy), a catabolic process involving autophagy-related (Atg) genes, prevents the accumulation of harmful cytoplasmic components and mobilizes energy reserves in long-lived and self-renewing cells. Autophagy deficiency affects antigen presentation in conventional dendritic cells (DCs) without impacting their survival. However, previous studies did not address epidermal Langerhans cells (LCs). Here, we demonstrate that deletion of either Atg5 or Atg7 in LCs leads to their gradual depletion. ATG5-deficient LCs showed metabolic dysregulation and accumulated neutral lipids. Despite increased mitochondrial respiratory capacity, they were unable to process lipids, eventually leading them to ferroptosis. Finally, metabolically impaired LCs upregulated proinflammatory transcripts and showed decreased expression of neuronal interaction receptors. Altogether, autophagy represents a critical regulator of lipid storage and metabolism in LCs, allowing their maintenance in the epidermis.

Mechanism of action of Panax ginseng alcohol extract based on orexin-mediated autophagy in the treatment of sleep and cognition in aged sleep-deprived rats

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng (P. ginseng) C. A. Meyer. has been used extensively globally as a medicine. It has a therapeutic effect on sleep and is an attractive alternative for patients with insomnia. The United States Patent of Invention has approved the use of P. ginseng alcohol extract (GAE) in nutraceuticals or food to improve sleep. It has shown promise as an effective therapeutic agent for improving sleep and cognition. However, its mechanism of action is not yet fully understood.

AIM OF THE STUDY

To investigate the therapeutic benefits of GAE on sleep and cognition and its underlying mechanism in aged sleep-deprived rats, with a focus on orexin-mediated autophagy function.

MATERIALS AND METHODS

We conducted in vivo tests in an aged sleep-deprivation rat model produced using p-chlorophenylalanine (PCPA) coupled with modified multi-platform method to examine the therapeutic effects and mechanisms of GAE. A pentobarbital sodium-induced sleep test and water maze were used to assess sleep and cognitive performance, respectively. An enzyme-linked immunosorbent assay was used to determine orexin levels and aging and sleep markers in serum and hypothalamic tissues. Hematoxylin-eosin staining and Nissl staining were used to assess histopathological changes, and autophagy levels were assessed using transmission electron microscopy, immunofluorescence. Western blot and immunohistochemical staining were performed to detect the levels of orexin, orexin-receptor proteins, and autophagy-associated proteins to study the effects of GAE on hippocampal neurons, and the underlying mechanisms.

RESULTS

In aged sleep-deprived rats, GAE treatment prolonged sleep duration, improved cognitive function, prevented hippocampal neuronal damage, increased the number of Nissl bodies, improved aging and sleep markers, and enhanced the LC3A/B expression in autophagosomes and neurons. The amount of orexin in serum and hypothalamic tissue and OX1R, OX2R, and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) proteins also reduced, which resulted in the inhibition of the PI3K/Akt/mTOR pathway and activation of the autophagy process.

CONCLUSIONS

GAE may reduce hypothalamic orexin secretion and interact with orexin receptors to inhibit the PI3K/Akt/mTOR signalling network and activate autophagy. This may be a potential mechanism of action of GAE in regulating sleep-related cognitive function.

Novel prospects in targeting neurodegenerative disorders via autophagy

Protein aggregation occurs as a consequence of dysfunction in the normal cellular proteostasis, which leads to the accumulation of toxic fibrillar aggregates of certain proteins in the cell. Enhancing the activity of proteolytic pathways may serve as a way of clearing these aggregates in a cell, and consequently, autophagy has surfaced as a promising target for the treatment of neurodegenerative disorders. Several strategies involving small molecule compounds that stimulate autophagic pathway of cell have been discovered. However, despite many compounds having demonstrated favorable outcomes in experimental disease models, the translation of these findings into clinical benefits for patient's remains limited. Consequently, alternative strategies are actively being explored to effectively target neurodegeneration via autophagy modulation. Recently, newer approaches such as modulation of expression of autophagic genes have emerged as novel and interesting areas of research in this field, which hold promising potential in neuroprotection. Similarly, as discussed for the first time in this review, the use of autophagy-inducing nanoparticles by utilizing their physicochemical properties to stimulate the autophagic process, rather than relying on their role as drug carriers, offers a completely fresh avenue for targeting neurodegeneration without the risk of drug-associated adverse effects. This review provides fresh perspectives on developing autophagy-targeted therapies for neurodegenerative disorders. Additionally, it discusses the challenges and impediments of implementing these strategies to alleviate the pathogenesis of neurodegenerative disorders in clinical settings and highlights the prospects and directions of future research in this context.

Targeted protein degradation: expanding the technology to facilitate the clearance of neurotoxic proteins in neurodegenerative diseases

In neurodegenerative diseases (NDDs), disruptions in protein homeostasis hinder the clearance of misfolded proteins, causing the formation of misfolded protein oligomers and multimers. The accumulation of these abnormal proteins results in the onset and progression of NDDs. Removal of non-native protein is essential for cell to maintain proteostasis. In recent years, targeted protein degradation (TPD) technologies have become a novel means of treating NDDs by removing misfolded proteins through the intracellular protein quality control system. The TPD strategy includes the participation of two primary pathways, namely the ubiquitin-proteasome pathway (for instance, PROTAC, molecular glue and hydrophobic tag), and the autophagy-lysosome pathway (such as LYTAC, AUTAC and ATTEC). In this review, we systematically present the mechanisms of various TPD strategies employed for neurotoxic protein degradation in NDDs. The article provides an overview of the design, in vitro and in vivo anti-NDD activities and pharmacokinetic properties of these small-molecular degraders. Finally, the advantages, challenges and perspectives of these TPD technologies in NDDs therapy are discussed, providing ideas for further development of small molecule degraders in the realm of NDDs.

The role of autophagy in brain health and disease: Insights into exosome and autophagy interactions

Effective management of cellular components is essential for maintaining brain health, and studies have identified several crucial biological processes in the brain. Among these, autophagy and the role of exosomes in cellular communication are critical for brain health and disease. The interaction between autophagy and exosomes in the nervous system, as well as their contributions to brain damage, have garnered significant attention. This review summarizes that exosomes and their cargoes have been implicated in the autophagy process in the pathophysiology of nervous system diseases. Furthermore, the onset and progression of neurological disorders may be affected by autophagy regulation of the secretion and release of exosomes. These findings may provide new insights into the potential mechanism by which autophagy mediates different exosome secretion and release, as well as the valuable biomedical applications of exosomes in the prevention and treatment of various brain diseases by targeting autophagy.

STING orchestrates microglia polarization via interaction with LC3 in autophagy after ischemia

Autophagy has both protective and pathogenetic effects on injury caused by cerebral ischemia/reperfusion (I/R). Our previous research has indicated that stimulator of interferon genes (STING) could orchestrate microglia polarization following middle cerebral artery occlusion. However, it remains largely unexplored whether STING balances microglial polarization by regulating autophagy in brain I/R injury. Here, STING was observed to show an up-regulation in the microglia from mice subjected to experimental ischemic stroke. Strikingly, the deletion of STING led to the significant skewness of microglia activated by ischemia from a pro- to anti-inflammatory state and substantially alleviated ischemia-induced infarction and neuronal injury. In addition, STING-null mice can restore long-term neurobehavioral function. Then, the crosstalk between neuroinflammation and microglia autophagy was analyzed. The differential activity of autophagy in wild-type and STING-knockout (KO) mice or primary microglia was largely reversed when STING was restored in microglia. Irritating autophagy by rapamycin skewed the anti‑inflammatory state induced by STING-KO to a pro‑inflammatory state in microglia. Furthermore, microtubule-associated protein light-chain-3 (LC3) was identified as the key factor in the STING regulation of autophagy by glutathione-S-transferase (GST) pull-down analysis. Mechanically, STING can directly interact with LC3 through the STING transmembrane domain (1-139aa). Herein, current data determine the pivotal role of autophagy, specifically via LC3 protein, in the regulation of microglial phenotypic transformation by STING. These findings may provide a possible treatment target for delaying the progression of ischemic stroke.

Highlighting roles of autophagy in human diseases: a perspective from single-cell RNA sequencing analyses

Autophagy, the lysosome-driven breakdown of intracellular components, is pivotal in regulating eukaryotic cellular processes and maintaining homeostasis, making it physiologically important even under normal conditions. Cellular mechanisms that involve autophagy include the starvation response, intracellular quality control, early development, and cell differentiation. Despite its established health significance, the role of autophagy in cancer and other diseases is unclear. It is important to understand this mechanism thoroughly so that innovative therapies against various diseases can be designed and implemented and so that drugs can be developed to protect human health. High-throughput technologies have allowed researchers to study transcriptional landscapes at single-cell resolution, improving our understanding of autophagy pathways in various physiological and pathological conditions. This paper discusses single-cell RNA sequencing advances in autophagy research and the molecular characterization of multiple diseases.

Legius Syndrome mutations in the Ras-regulator SPRED1 abolish its membrane localization and potentially cause neurodegeneration

The SPRED family proteins act as negative regulators of the Ras-ERK pathway: the N-terminal EVH1 domain interacts with the Ras-GAP domain (GRD) of the NF1 protein, while the C-terminal Sprouty-related (SPR) domain promotes membrane localization of SPRED, thereby recruiting NF-1 to Ras. Loss-of-function mutations in the hSPRED1 cause Legius syndrome in an autosomal dominant manner. In this study, we investigated the effects of missense mutations in the SPR domain identified in patients with Legius syndrome. Among 18 mutations we examined, six (C368S, M369L, V408E, P415A, P415L and P422R) have defects in the palmitoylation of the SPRED1 protein, losing plasma membrane localization and forming cytoplasmic granular aggregates. To evaluate the in vivo effects of SPR mutations, knock-in (KI) mice with P415A and P415V substitutions or M417Afs*4, a C-terminal 28 amino acid deletion, were generated. All these KI mice exhibited cranial malformations, a characteristic feature of Legius syndrome. However, both P415A and P415V mutants formed granular aggregates, whereas M417Afs*4 showed a diffuse cytoplasmic distribution, and Spred1P415A and Spred1P415V mice, but not Spred1M417Afs∗4 mice, developed cerebellar ataxia and Purkinje cell loss with age. These data suggest that in addition to loss of palmitoylation, the C-terminal region is required for the granular aggregate formation and Purkinje cell loss. The autophagy inducer spermidine rescued the ataxia phenotypes and Purkinje cell loss in Spred1P415A mice. These results suggest that some, but not all, SPR mutations that lose lipid modification induce abnormal cytoplasmic aggregation, which could be a target for autophagic clearance, and potentially cause neurodegenerative diseases.

Mechanisms of autophagy-lysosome dysfunction in neurodegenerative diseases

Autophagy is a lysosome-based degradative process used to recycle obsolete cellular constituents and eliminate damaged organelles and aggregate-prone proteins. Their postmitotic nature and extremely polarized morphologies make neurons particularly vulnerable to disruptions caused by autophagy-lysosomal defects, especially as the brain ages. Consequently, mutations in genes regulating autophagy and lysosomal functions cause a wide range of neurodegenerative diseases. Here, we review the role of autophagy and lysosomes in neurodegenerative diseases such as Alzheimer disease, Parkinson disease and frontotemporal dementia. We also consider the strong impact of cellular ageing on lysosomes and autophagy as a tipping point for the late-age emergence of related neurodegenerative disorders. Many of these diseases have primary defects in autophagy, for example affecting autophagosome formation, and in lysosomal functions, especially pH regulation and calcium homeostasis. We have aimed to provide an integrative framework for understanding the central importance of autophagic-lysosomal function in neuronal health and disease.

Emerging roles of ATG9/ATG9A in autophagy: implications for cell and neurobiology

Atg9, the only transmembrane protein among many autophagy-related proteins, was first identified in the year 2000 in yeast. Two homologs of Atg9, ATG9A and ATG9B, have been found in mammals. While ATG9B shows a tissue-specific expression pattern, such as in the placenta and pituitary gland, ATG9A is ubiquitously expressed. Additionally, ATG9A deficiency leads to severe defects not only at the molecular and cellular levels but also at the organismal level, suggesting key and fundamental roles for ATG9A. The subcellular localization of ATG9A on small vesicles and its functional relevance to autophagy have suggested a potential role for ATG9A in the lipid supply during autophagosome biogenesis. Nevertheless, the precise role of ATG9A in the autophagic process has remained a long-standing mystery, especially in neurons. Recent findings, however, including structural, proteomic, and biochemical analyses, have provided new insights into its function in the expansion of the phagophore membrane. In this review, we aim to understand various aspects of ATG9 (in invertebrates and plants)/ATG9A (in mammals), including its localization, trafficking, and other functions, in nonneuronal cells and neurons by comparing recent discoveries related to ATG9/ATG9A and proposing directions for future research.Abbreviation: AP-4: adaptor protein complex 4; ATG: autophagy related; cKO: conditional knockout; CLA-1: CLArinet (functional homolog of cytomatrix at the active zone proteins piccolo and fife); cryo-EM: cryogenic electron microscopy; ER: endoplasmic reticulum; KO: knockout; PAS: phagophore assembly site; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; RB1CC1/FIP200: RB1 inducible coiled-coil 1; SV: synaptic vesicle; TGN: trans-Golgi network; ULK: unc-51 like autophagy activating kinase; WIPI2: WD repeat domain, phosphoinositide interacting 2.

Transcriptional changes impact hepatic proteome in autophagy-impaired liver

Hepatic proteomes are intricately controlled through biosynthesis, extracellular secretion, and intrahepatic degradation. Autophagy governs lysosome-mediated intrahepatic degradation and the hepatic proteome. When autophagy is impaired, it leads to the accumulation of intrahepatic proteins, causing proteinopathy. This study investigates whether autophagy can modulate the hepatic proteome non-degradatively. Utilizing conditional, inducible, and hepatotoxin models of hepatic autophagy impairment, we assessed the overall hepatic proteome expression using Coomassie brilliant blue (CBB) staining and liquid chromatography-tandem mass spectrometry (LC/MS). We pinpointed and confirmed four specific hepatic proteins-Cps1, Ahcy, Ca3, and Gstm1-that were selectively modified in autophagy-deficient livers. Expression of Cps1, Ahcy, and Ca3 were significantly reduced, while Gstm1 expression increased in livers with autophagy impairment. Interestingly, these changes in hepatic protein levels were not due to defective autophagic degradation but were associated with alterations in mRNA transcript levels. Moreover, as a result of autophagic dysfunction, sustained activation of the nuclear erythroid-derived 2-like 2 (Nrf2) transcription factor, transcriptionally regulated the mRNA levels of these proteins. Our findings indicate that autophagy can influence hepatic proteins not solely via traditional degradative routes but also through non-degradative transcriptional processes by modulating Nrf2.

Adult-onset deactivation of autophagy leads to loss of synapse homeostasis and cognitive impairment, with implications for alzheimer disease

A growing number of studies link dysfunction of macroautophagy/autophagy to the pathogenesis of diseases such as Alzheimer disease (AD). Given the global importance of autophagy for homeostasis, how its dysfunction can lead to specific neurological changes is puzzling. To examine this further, we compared the global deactivation of autophagy in the adult mouse using the atg7iKO with the impact of AD-associated pathogenic changes in autophagic processing of synaptic proteins. Isolated forebrain synaptosomes, rather than total homogenates, from atg7iKO mice demonstrated accumulation of synaptic proteins, suggesting that the synapse might be a vulnerable site for protein homeostasis disruption. Moreover, the deactivation of autophagy resulted in impaired cognitive performance over time, whereas gross locomotor skills remained intact. Despite deactivation of autophagy for 6.5 weeks, changes in cognition were in the absence of cell death or synapse loss. In the symptomatic APP PSEN1 double-transgenic mouse model of AD, we found that the impairment in autophagosome maturation coupled with diminished presence of discrete synaptic proteins in autophagosomes isolated from these mice, leading to the accumulation of one of these proteins in the detergent insoluble protein fraction. This protein, SLC17A7/Vglut, also accumulated in atg7iKO mouse synaptosomes. Taken together, we conclude that synaptic autophagy plays a role in maintaining protein homeostasis, and that while decreasing autophagy interrupts normal cognitive function, the preservation of locomotion suggests that not all circuits are affected similarly. Our data suggest that the disruption of autophagic activity in AD may have relevance for the cognitive impairment in this adult-onset neurodegenerative disease. Abbreviations: 2dRAWM: 2-day radial arm water maze; AD: Alzheimer disease; Aβ: amyloid-beta; AIF1/Iba1: allograft inflammatory factor 1; APP: amyloid beta precursor protein; ATG7: autophagy related 7; AV: autophagic vacuole; CCV: cargo capture value; Ctrl: control; DLG4/PSD-95: discs large MAGUK scaffold protein 4; GFAP: glial fibrillary acidic protein; GRIN2B/NMDAR2b: glutamate ionotropic receptor NMDA type subunit 2B; LTD: long-term depression; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; m/o: months-old; PNS: post-nuclear supernatant; PSEN1/PS1: presenilin 1; SHB: sucrose homogenization buffer; SLC32A1/Vgat: solute carrier family 32 member 1; SLC17A7/Vglut1: solute carrier family 17 member 7; SNAP25: synaptosome associated protein 25; SQSTM1/p62: sequestosome 1; SYN1: synapsin I; SYP: synaptophysin ; SYT1: synaptotagmin 1; Tam: tamoxifen; VAMP2: vesicle associated membrane protein 2; VCL: vinculin; wks: weeks.

Targeting selective autophagy in CNS disorders by small-molecule compounds

Autophagy functions as the primary cellular mechanism for clearing unwanted intracellular contents. Emerging evidence suggests that the selective elimination of intracellular organelles through autophagy, compared to the increased bulk autophagic flux, is crucial for the pathological progression of central nervous system (CNS) disorders. Notably, autophagic removal of mitochondria, known as mitophagy, is well-understood in an unhealthy brain. Accumulated data indicate that selective autophagy of other substrates, including protein aggregates, liposomes, and endoplasmic reticulum, plays distinctive roles in various pathological stages. Despite variations in substrates, the molecular mechanisms governing selective autophagy can be broadly categorized into two types: ubiquitin-dependent and -independent pathways, both of which can be subjected to regulation by small-molecule compounds. Notably, natural products provide the remarkable possibility for future structural optimization to regulate the highly selective autophagic clearance of diverse substrates. In this context, we emphasize the selectivity of autophagy in regulating CNS disorders and provide an overview of chemical compounds capable of modulating selective autophagy in these disorders, along with the underlying mechanisms. Further exploration of the functions of these compounds will in turn advance our understanding of autophagic contributions to brain disorders and illuminate precise therapeutic strategies for these diseases.

Increased DNA damage in full-grown oocytes is correlated with diminished autophagy activation

Unlike mild DNA damage exposure, DNA damage repair (DDR) is reported to be ineffective in full-grown mammalian oocytes exposed to moderate or severe DNA damage. The underlying mechanisms of this weakened DDR are unknown. Here, we show that moderate DNA damage in full-grown oocytes leads to aneuploidy. Our data reveal that DNA-damaged oocytes have an altered, closed, chromatin state, and suggest that the failure to repair damaged DNA could be due to the inability of DDR proteins to access damaged loci. Our data also demonstrate that, unlike somatic cells, mouse and porcine oocytes fail to activate autophagy in response to DNA double-strand break-inducing treatment, which we suggest may be the cause of the altered chromatin conformation and inefficient DDR. Importantly, autophagy activity is further reduced in maternally aged oocytes (which harbor severe DNA damage), and its induction is correlated with reduced DNA damage in maternally aged oocytes. Our findings provide evidence that reduced autophagy activation contributes to weakened DDR in oocytes, especially in those from aged females, offering new possibilities to improve assisted reproductive therapy in women with compromised oocyte quality.

Autophagy-lysosomal pathway impairment and cathepsin dysregulation in Alzheimer's disease

Alzheimer's disease (AD) is characterized by neuronal loss, attributed to amyloid-beta (Aβ) aggregation and accumulation. The autophagy-lysosomal pathway, including cathepsins B and D, is crucial for protein degradation and clearance, but it is impaired in some diseases. This review summarizes current knowledge on the dysregulation of this pathway in AD. Accumulating evidence suggests that Aβ overload impairs autophagy-lysosomal function and cathepsin activity, exacerbating Aβ accumulation and neurodegeneration. However, the precise mechanisms underlying these interactions remain elusive. Despite these challenges, targeting the lysosomal pathway emerges as a promising therapeutic strategy, and a comprehensive understanding of the autophagy-lysosomal system is essential to develop effective interventions for AD.

Can salivary and skin microbiome become a biodetector for aging-associated diseases? Current insights and future perspectives

Growth and aging are fundamental elements of human development. Aging is defined by a decrease in physiological activities and higher illness vulnerability. Affected by lifestyle, environmental, and hereditary elements, aging results in disorders including cardiovascular, musculoskeletal, and neurological diseases, which accounted for 16.1 million worldwide deaths in 2019. Stress-induced cellular senescence, caused by DNA damage, can reduce tissue regeneration and repair, promoting aging. The root cause of many age-related disorders is inflammation, encouraged by the senescence-associated secretory phenotype (SASP). Aging's metabolic changes and declining immune systems raise illness risk via promoting microbiome diversity. Stable, individual-specific skin and oral microbiomes are essential for both health and disease since dysbiosis is linked with periodontitis and eczema. Present from birth to death, the human microbiome, under the influence of diet and lifestyle, interacts symbiotically with the body. Poor dental health has been linked to Alzheimer's and Parkinson's diseases since oral microorganisms and systemic diseases have important interactions. Emphasizing the importance of microbiome health across the lifetime, this study reviews the understanding of the microbiome's role in aging-related diseases that can direct novel diagnosis and treatment approaches.

Posttranslational Modifications of -Synuclein, Their Therapeutic Potential, and Crosstalk in Health and Neurodegenerative Diseases

α-Synuclein (α-Syn) aggregation in Lewy bodies and Lewy neurites has emerged as a key pathogenetic feature in Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Various factors, including posttranslational modifications (PTMs), can influence the propensity of α-Syn to misfold and aggregate. PTMs are biochemical modifications of a protein that occur during or after translation and are typically mediated by enzymes. PTMs modulate several characteristics of proteins including their structure, activity, localization, and stability. α-Syn undergoes various posttranslational modifications, including phosphorylation, ubiquitination, SUMOylation, acetylation, glycation, O-GlcNAcylation, nitration, oxidation, polyamination, arginylation, and truncation. Different PTMs of a protein can physically interact with one another or work together to influence a particular physiological or pathological feature in a process known as PTMs crosstalk. The development of detection techniques for the cooccurrence of PTMs in recent years has uncovered previously unappreciated mechanisms of their crosstalk. This has led to the emergence of evidence supporting an association between α-Syn PTMs crosstalk and synucleinopathies. In this review, we provide a comprehensive evaluation of α-Syn PTMs, their impact on misfolding and pathogenicity, the pharmacological means of targeting them, and their potential as biomarkers of disease. We also highlight the importance of the crosstalk between these PTMs in α-Syn function and aggregation. Insight into these PTMS and the complexities of their crosstalk can improve our understanding of the pathogenesis of synucleinopathies and identify novel targets of therapeutic potential. SIGNIFICANCE STATEMENT: α-Synuclein is a key pathogenic protein in Parkinson's disease and other synucleinopathies, making it a leading therapeutic target for disease modification. Multiple posttranslational modifications occur at various sites in α-Synuclein and alter its biophysical and pathological properties, some interacting with one another to add to the complexity of the pathogenicity of this protein. This review details these modifications, their implications in disease, and potential therapeutic opportunities.

Plekhg5 controls the unconventional secretion of Sod1 by presynaptic secretory autophagy

Increasing evidence suggests an essential function for autophagy in unconventional protein secretion (UPS). However, despite its relevance for the secretion of aggregate-prone proteins, the mechanisms of secretory autophagy in neurons have remained elusive. Here we show that the lower motoneuron disease-associated guanine exchange factor Plekhg5 drives the UPS of Sod1. Mechanistically, Sod1 is sequestered into autophagosomal carriers, which subsequently fuse with secretory lysosomal-related organelles (LROs). Exocytosis of LROs to release Sod1 into the extracellular milieu requires the activation of the small GTPase Rab26 by Plekhg5. Deletion of Plekhg5 in mice leads to the accumulation of Sod1 in LROs at swollen presynaptic sites. A reduced secretion of toxic ALS-linked SOD1G93A following deletion of Plekhg5 in SOD1G93A mice accelerated disease onset while prolonging survival due to an attenuated microglia activation. Using human iPSC-derived motoneurons we show that reduced levels of PLEKHG5 cause an impaired secretion of ALS-linked SOD1. Our findings highlight an unexpected pathophysiological mechanism that converges two motoneuron disease-associated proteins into a common pathway.

Longitudinal autophagy profiling of the mammalian brain reveals sustained mitophagy throughout healthy aging

Mitophagy neutralizes mitochondrial damage, thereby preventing cellular dysfunction and apoptosis. Defects in mitophagy have been strongly implicated in age-related neurodegenerative disorders such as Parkinson's and Alzheimer's disease. While mitophagy decreases throughout the lifespan of short-lived model organisms, it remains unknown whether such a decline occurs in the aging mammalian brain-a question of fundamental importance for understanding cell type- and region-specific susceptibility to neurodegeneration. Here, we define the longitudinal dynamics of basal mitophagy and macroautophagy across neuronal and non-neuronal cell types within the intact aging mouse brain in vivo. Quantitative profiling of reporter mouse cohorts from young to geriatric ages reveals cell- and tissue-specific alterations in mitophagy and macroautophagy between distinct subregions and cell populations, including dopaminergic neurons, cerebellar Purkinje cells, astrocytes, microglia and interneurons. We also find that healthy aging is hallmarked by the dynamic accumulation of differentially acidified lysosomes in several neural cell subsets. Our findings argue against any widespread age-related decline in mitophagic activity, instead demonstrating dynamic fluctuations in mitophagy across the aging trajectory, with strong implications for ongoing theragnostic development.

Lysosomal physiology and pancreatic lysosomal stress in diabetes mellitus

Endocrine and exocrine functions of the pancreas control nutritional absorption, utilisation and systemic metabolic homeostasis. Under basal conditions, the lysosome is pivotal in regulating intracellular organelles and metabolite turnover. In response to acute or chronic stress, the lysosome senses metabolic flux and inflammatory challenges, thereby initiating the adaptive programme to re-establish cellular homeostasis. A growing body of evidence has demonstrated the pathophysiological relevance of the lysosomal stress response in metabolic diseases in diverse sets of tissues/organs, such as the liver and the heart. In this review, we discuss the pathological relevance of pancreatic lysosome stress in diabetes mellitus. We begin by summarising lysosomal biology, followed by exploring the immune and metabolic functions of lysosomes and finally discussing the interplay between lysosomal stress and the pathogenesis of pancreatic diseases. Ultimately, our review aims to enhance our understanding of lysosomal stress in disease pathogenesis, which could potentially lead to the discovery of innovative treatment methods for these conditions.

Diabetic retinopathy from the vitreous proteome perspective: The INSC94Y transgenic pig model study

INSC94Y transgenic pigs represent a model for mutant insulin gene-induced diabetes of youth, with impaired insulin secretion and beta cell loss, leading to elevated fasting blood glucose levels. A key complication of diabetes mellitus is diabetic retinopathy (DR), characterized by hyperglycemia-induced abnormalities in the retina. Adjacent to the retina lies the vitreous, a gelatinous matrix vital for ocular function. It harbors proteins and signaling molecules, offering insights into vitreous biology and ocular health. Moreover, as a reservoir for secreted molecules, the vitreous illuminates molecular processes within intraocular structures, especially under pathological conditions. To uncover the proteomic profile of porcine vitreous and explore its relevance to DR, we employed discovery proteomics to compare vitreous samples from INSC94Y transgenic pigs and wild-type controls. Our analysis identified 1404 proteins, with 266 showing differential abundance in INSC94Y vitreous. Notably, the abundances of ITGB1, COX2, and GRIFIN were significantly elevated in INSC94Y vitreous. Gene Set Enrichment Analysis unveiled heightened MYC and mTORC1 signaling in INSC94Y vitreous, shedding light on its biological significance in diabetes-associated ocular pathophysiology. These findings deepen our understanding of vitreous involvement in DR and provide valuable insights into potential therapeutic targets. Raw data are accessible via ProteomeXchange (PXD038198).

Autophagy in aging-related diseases and cancer: Principles, regulatory mechanisms and therapeutic potential

Macroautophagy/autophagy is primarily accountable for the degradation of damaged organelles and toxic macromolecules in the cells. Regarding the essential function of autophagy for preserving cellular homeostasis, changes in, or dysfunction of, autophagy flux can lead to disease development. In the current paper, the complicated function of autophagy in aging-associated pathologies and cancer is evaluated, highlighting the underlying molecular mechanisms that can affect longevity and disease pathogenesis. As a natural biological process, a reduction in autophagy is observed with aging, resulting in an accumulation of cell damage and the development of different diseases, including neurological disorders, cardiovascular diseases, and cancer. The MTOR, AMPK, and ATG proteins demonstrate changes during aging, and they are promising therapeutic targets. Insulin/IGF1, TOR, PKA, AKT/PKB, caloric restriction and mitochondrial respiration are vital for lifespan regulation and can modulate or have an interaction with autophagy. The specific types of autophagy, such as mitophagy that degrades mitochondria, can regulate aging by affecting these organelles and eliminating those mitochondria with genomic mutations. Autophagy and its specific types contribute to the regulation of carcinogenesis and they are able to dually enhance or decrease cancer progression. Cancer hallmarks, including proliferation, metastasis, therapy resistance and immune reactions, are tightly regulated by autophagy, supporting the conclusion that autophagy is a promising target in cancer therapy.

AdipoRon promotes amyloid-β clearance through enhancing autophagy via nuclear GAPDH-induced sirtuin 1 activation in Alzheimer's disease

BACKGROUND AND PURPOSE

Amyloid-β (Aβ) peptide is one of the more important pathological markers in Alzheimer's disease (AD). The development of AD impairs autophagy, which results in an imbalanced clearance of Aβ. Our previous research demonstrated that AdipoRon, an agonist of adiponectin receptors, decreased the deposition of Aβ and enhanced cognitive function in AD. However, the exact mechanisms by which AdipoRon affects Aβ clearance remain unclear.

EXPERIMENTAL APPROACH

We studied how AdipoRon affects autophagy in HT22 cells and APP/PS1 transgenic mice. We also investigated the signalling pathway involved and used pharmacological inhibitors to examine the role of autophagy in this process.

KEY RESULTS

AdipoRon promotes Aβ clearance by activating neuronal autophagy in the APP/PS1 transgenic mice. Interestingly, we found that AdipoRon induces the nuclear translocation of GAPDH, where it interacts with the SIRT1/DBC1 complex. This interaction then leads to the release of DBC1 and the activation of SIRT1, which in turn activates autophagy. Importantly, we found that inhibiting either GAPDH or SIRT1 to suppress the activity of SIRT1 counteracts the elevated autophagy and decreased Aβ deposition caused by AdipoRon. This suggests that SIRT1 plays a critical role in the effect of AdipoRon on autophagic induction in AD.

CONCLUSION AND IMPLICATIONS

AdipoRon promotes the clearance of Aβ by enhancing autophagy through the AdipoR1/AMPK-dependent nuclear translocation of GAPDH and subsequent activation of SIRT1. This novel molecular pathway sheds light on the modulation of autophagy in AD and may lead to the development of new therapeutic strategies targeting this pathway.

Pathological characteristics of axons and alterations of proteomic and lipidomic profiles in midbrain dopaminergic neurodegeneration induced by WDR45-deficiency

BACKGROUND

Although WD repeat domain 45 (WDR45) mutations have been linked to β -propeller protein-associated neurodegeneration (BPAN), the precise molecular and cellular mechanisms behind this disease remain elusive. This study aims to shed light on the impacts of WDR45-deficiency on neurodegeneration, specifically axonal degeneration, within the midbrain dopaminergic (DAergic) system. We hope to better understand the disease process by examining pathological and molecular alterations, especially within the DAergic system.

METHODS

To investigate the impacts of WDR45 dysfunction on mouse behaviors and DAergic neurons, we developed a mouse model in which WDR45 was conditionally knocked out in the midbrain DAergic neurons (WDR45cKO). Through a longitudinal study, we assessed alterations in the mouse behaviors using open field, rotarod, Y-maze, and 3-chamber social approach tests. We utilized a combination of immunofluorescence staining and transmission electron microscopy to examine the pathological changes in DAergic neuron soma and axons. Additionally, we performed proteomic and lipidomic analyses of the striatum from young and aged mice to identify the molecules and processes potentially involved in the striatal pathology during aging. Further more, primary midbrain neuronal culture was employed to explore the molecular mechanisms leading to axonal degeneration.

RESULTS

Our study of WDR45cKO mice revealed a range of deficits, including impaired motor function, emotional instability, and memory loss, coinciding with the profound reduction of midbrain DAergic neurons. The neuronal loss, we observed massive axonal enlargements in the dorsal and ventral striatum. These enlargements were characterized by the accumulation of extensively fragmented tubular endoplasmic reticulum (ER), a hallmark of axonal degeneration. Proteomic analysis of the striatum showed that the differentially expressed proteins were enriched in metabolic processes. The carbohydrate metabolic and protein catabolic processes appeared earlier, and amino acid, lipid, and tricarboxylic acid metabolisms were increased during aging. Of note, we observed a tremendous increase in the expression of lysophosphatidylcholine acyltransferase 1 (Lpcat1) that regulates phospholipid metabolism, specifically in the conversion of lysophosphatidylcholine (LPC) to phosphatidylcholine (PC) in the presence of acyl-CoA. The lipidomic results consistently suggested that differential lipids were concentrated on PC and LPC. Axonal degeneration was effectively ameliorated by interfering Lpcat1 expression in primary cultured WDR45-deficient DAergic neurons, proving that Lpcat1 and its regulated lipid metabolism, especially PC and LPC metabolism, participate in controlling the axonal degeneration induced by WDR45 deficits.

CONCLUSIONS

In this study, we uncovered the molecular mechanisms underlying the contribution of WDR45 deficiency to axonal degeneration, which involves complex relationships between phospholipid metabolism, autophagy, and tubular ER. These findings greatly advance our understanding of the fundamental molecular mechanisms driving axonal degeneration and may provide a foundation for developing novel mechanistically based therapeutic interventions for BPAN and other neurodegenerative diseases.

Mechanical stress-induced autophagy is cytoskeleton dependent

The cytoskeleton is essential for mechanical signal transduction and autophagy. However, few studies have directly demonstrated the contribution of the cytoskeleton to mechanical stress-induced autophagy. We explored the role of the cytoskeleton in response to compressive force-induced autophagy in human cell lines. Inhibition and activation of cytoskeletal polymerization using small chemical molecules revealed that cytoskeletal microfilaments are required for changes in the number of autophagosomes, whereas microtubules play an auxiliary role in mechanical stress-induced autophagy. The intrinsic mechanical properties and special intracellular distribution of microfilaments may account for a large proportion of compression-induced autophagy. Our experimental data support that microfilaments are core components of mechanotransduction signals.

Molecular Insights into Aggrephagy: Their Cellular Functions in the Context of Neurodegenerative Diseases

Protein homeostasis or proteostasis is an equilibrium of biosynthetic production, folding and transport of proteins, and their timely and efficient degradation. Proteostasis is guaranteed by a network of protein quality control systems aimed at maintaining the proteome function and avoiding accumulation of potentially cytotoxic proteins. Terminal unfolded and dysfunctional proteins can be directly turned over by the ubiquitin-proteasome system (UPS) or first amassed into aggregates prior to degradation. Aggregates can also be disposed into lysosomes by a selective type of autophagy known as aggrephagy, which relies on a set of so-called selective autophagy receptors (SARs) and adaptor proteins. Failure in eliminating aggregates, also due to defects in aggrephagy, can have devastating effects as underscored by several neurodegenerative diseases or proteinopathies, which are characterized by the accumulation of aggregates mostly formed by a specific disease-associated, aggregate-prone protein depending on the clinical pathology. Despite its medical relevance, however, the process of aggrephagy is far from being understood. Here we review the findings that have helped in assigning a possible function to specific SARs and adaptor proteins in aggrephagy in the context of proteinopathies, and also highlight the interplay between aggrephagy and the pathogenesis of proteinopathies.

Structural and dynamics insights into the GBA variants associated with Parkinson's disease

The GBA1 gene encodes for the lysosomal enzyme glucocerebrosidase (GCase), which maintains glycosphingolipid homeostasis and regulates the autophagy process. Genomic variants of GBA1 are associated with Goucher disease; however, several heterozygous variants of GBA (E326K, T369M, N370S, L444P) are frequent high-risk factors for Parkinson's disease (PD). The underlying mechanism of these variants has been revealed through functional and patient-centered research, but the structural and dynamical aspects of these variants have not yet been thoroughly investigated. In the current study, we used a thorough computational method to pinpoint the structural changes that GBA underwent because of genomic variants and drug binding mechanisms. According to our findings, PD-linked nsSNP variants of GBA showed structural variation and abnormal dynamics when compared to wild-typ. The docking analysis demonstrated that the mutants E326K, N370S, and L444P have higher binding affinities for Ambroxol. Root means square deviation (RMSD), Root mean square fluctuation analysis (RMSF), and MM-GBSA analysis confirmed that the Ambroxol are more stable in the binding site of N370S and L444P, and that their binding affinities are stronger as compared to the wild-type and T369M variants of GBA. The evaluation of hydrogen bonds and the calculation of the free binding energy provided additional evidence in favor of this conclusion. When docked with Ambroxol, GBA demonstrated an increase in binding affinity and catalytic activity. Understanding the therapeutic efficacy and potential against the aforementioned changes in the GBA will be beneficial in order to use more efficient methods for developing novel drugs.

Inhibition of autophagy prevents cardiac dysfunction at early stages of cardiomyopathy in Bag3-deficient hearts

The HSP70 co-chaperone BAG3 targets unfolded proteins to degradation via chaperone assisted selective autophagy (CASA), thereby playing pivotal roles in the proteostasis of adult cardiomyocytes (CMs). However, the complex functions of BAG3 for regulating autophagy in cardiac disease are not completely understood. Here, we demonstrate that conditional inactivation of Bag3 in murine CMs leads to age-dependent dysregulation of autophagy, associated with progressive cardiomyopathy. Surprisingly, Bag3-deficient CMs show increased canonical and non-canonical autophagic flux in the juvenile period when first signs of cardiac dysfunction appear, but reduced autophagy during later stages of the disease. Juvenile Bag3-deficient CMs are characterized by decreased levels of soluble proteins involved in synchronous contraction of the heart, including the gap junction protein Connexin 43 (CX43). Reiterative administration of chloroquine (CQ), an inhibitor of canonical and non-canonical autophagy, but not inactivation of Atg5, restores normal concentrations of soluble cardiac proteins in juvenile Bag3-deficient CMs without an increase of detergent-insoluble proteins, leading to complete recovery of early-stage cardiac dysfunction in Bag3-deficient mice. We conclude that loss of Bag3 in CMs leads to age-dependent differences in autophagy and cardiac dysfunction. Increased non-canonical autophagic flux in the juvenile period removes soluble proteins involved in cardiac contraction, leading to early-stage cardiomyopathy, which is prevented by reiterative CQ treatment.

ATG5-mediated keratinocyte ferroptosis promotes M1 polarization of macrophages to aggravate UVB-induced skin inflammation

Autophagy participates in the regulation of ferroptosis. Among numerous autophagy-related genes (ATGs), ATG5 plays a pivotal role in ferroptosis. However, how ATG5-mediated ferroptosis functions in UVB-induced skin inflammation is still unclear. In this study, we unveil that the core ferroptosis inhibitor GPX4 is significantly decreased in human skin tissue exposed to sunlight. We report that ATG5 deletion in mouse keratinocytes strongly protects against UVB-induced keratinocyte ferroptosis and skin inflammation. Mechanistically, ATG5 promotes the autophagy-dependent degradation of GPX4 in UVB-exposed keratinocytes, which leads to UVB-induced keratinocyte ferroptosis. Furthermore, we find that IFN-γ secreted by ferroptotic keratinocytes facilitates the M1 polarization of macrophages, which results in the exacerbation of UVB-induced skin inflammation. Together, our data indicate that ATG5 exacerbates UVB-induced keratinocyte ferroptosis in the epidermis, which subsequently gives rise to the secretion of IFN-γ and M1 polarization. Our study provides novel evidence that targeting ATG5 may serve as a potential therapeutic strategy for the amelioration of UVB-caused skin damage.

Astrocytic autophagy plasticity modulates Aβ clearance and cognitive function in Alzheimer's disease

BACKGROUND

Astrocytes, one of the most resilient cells in the brain, transform into reactive astrocytes in response to toxic proteins such as amyloid beta (Aβ) in Alzheimer's disease (AD). However, reactive astrocyte-mediated non-cell autonomous neuropathological mechanism is not fully understood yet. We aimed our study to find out whether Aβ-induced proteotoxic stress affects the expression of autophagy genes and the modulation of autophagic flux in astrocytes, and if yes, how Aβ-induced autophagy-associated genes are involved Aβ clearance in astrocytes of animal model of AD.

METHODS

Whole RNA sequencing (RNA-seq) was performed to detect gene expression patterns in Aβ-treated human astrocytes in a time-dependent manner. To verify the role of astrocytic autophagy in an AD mouse model, we developed AAVs expressing shRNAs for MAP1LC3B/LC3B (LC3B) and Sequestosome1 (SQSTM1) based on AAV-R-CREon vector, which is a Cre recombinase-dependent gene-silencing system. Also, the effect of astrocyte-specific overexpression of LC3B on the neuropathology in AD (APP/PS1) mice was determined. Neuropathological alterations of AD mice with astrocytic autophagy dysfunction were observed by confocal microscopy and transmission electron microscope (TEM). Behavioral changes of mice were examined through novel object recognition test (NOR) and novel object place recognition test (NOPR).

RESULTS

Here, we show that astrocytes, unlike neurons, undergo plastic changes in autophagic processes to remove Aβ. Aβ transiently induces expression of LC3B gene and turns on a prolonged transcription of SQSTM1 gene. The Aβ-induced astrocytic autophagy accelerates urea cycle and putrescine degradation pathway. Pharmacological inhibition of autophagy exacerbates mitochondrial dysfunction and oxidative stress in astrocytes. Astrocyte-specific knockdown of LC3B and SQSTM1 significantly increases Aβ plaque formation and GFAP-positive astrocytes in APP/PS1 mice, along with a significant reduction of neuronal marker and cognitive function. In contrast, astrocyte-specific overexpression of LC3B reduced Aβ aggregates in the brain of APP/PS1 mice. An increase of LC3B and SQSTM1 protein is found in astrocytes of the hippocampus in AD patients.

CONCLUSIONS

Taken together, our data indicates that Aβ-induced astrocytic autophagic plasticity is an important cellular event to modulate Aβ clearance and maintain cognitive function in AD mice.

VMP1: a multifaceted regulator of cellular homeostasis with implications in disease pathology

Vacuole membrane protein 1 (VMP1) is an integral membrane protein that plays a pivotal role in cellular processes, particularly in the regulation of autophagy. Autophagy, a self-degradative mechanism, is essential for maintaining cellular homeostasis by degradation and recycling damaged organelles and proteins. VMP1 involved in the autophagic processes include the formation of autophagosomes and the subsequent fusion with lysosomes. Moreover, VMP1 modulates endoplasmic reticulum (ER) calcium levels, which is significant for various cellular functions, including protein folding and cellular signaling. Recent studies have also linked VMP1 to the cellular response against viral infections and lipid droplet (LD). Dysregulation of VMP1 has been observed in several pathological conditions, including neurodegenerative diseases such as Parkinson's disease (PD), pancreatitis, hepatitis, and tumorogenesis, underscoring its potential as a therapeutic target. This review aims to provide an overview of VMP1's multifaceted roles and its implications in disease pathology.

Endonucleosis mediates internalization of cytoplasm into the nucleus

Setd8 regulates transcription elongation, mitotic DNA condensation, DNA damage response and replication licensing. Here we show that, in mitogen-stimulated liver-specific Setd8-KO mice, most of the hepatocytes are eliminated by necrosis but a significant number of them survive via entering a stage exhibiting several senescence-related features. Setd8-deficient hepatocytes had enlarged nuclei, chromosomal hyperploidy and nuclear engulfments progressing to the formation of intranuclear vesicles surrounded by nuclear lamina. These vesicles contain glycogen, cytoplasmic proteins and even entire organelles. We term this process "endonucleosis". Intranuclear vesicles are absent in hepatocytes of Setd8/Atg5 knockout mice, suggesting that the process requires the function of the canonical autophagy machinery. Endonucleosis and hyperploidization are temporary, early events in the surviving Setd8-deficient cells. Larger vesicles break down into microvesicles over time and are eventually eliminated. The results reveal sequential events in cells with extensive DNA damage, which function as part of survival mechanisms to prevent necrotic death.

Pharmacology Progresses and Applications of Chloroquine in Cancer Therapy

Chloroquine is a common antimalarial drug and is listed in the World Health Organization Standard List of Essential Medicines because of its safety, low cost and ease of use. Besides its antimalarial property, chloroquine also was used in anti-inflammatory and antivirus, especially in antitumor therapy. A mount of data showed that chloroquine mainly relied on autophagy inhibition to exert its antitumor effects. However, recently, more and more researches have revealed that chloroquine acts through other mechanisms that are autophagy-independent. Nevertheless, the current reviews lacked a comprehensive summary of the antitumor mechanism and combined pharmacotherapy of chloroquine. So here we focused on the antitumor properties of chloroquine, summarized the pharmacological mechanisms of antitumor progression of chloroquine dependent or independent of autophagy inhibition. Moreover, we also discussed the side effects and possible application developments of chloroquine. This review provided a more systematic and cutting-edge knowledge involved in the anti-tumor mechanisms and combined pharmacotherapy of chloroquine in hope of carrying out more in-depth exploration of chloroquine and obtaining more clinical applications.

Ferritinophagy: A novel insight into the double-edged sword in ferritinophagy-ferroptosis axis and human diseases

Nuclear receptor coactive 4 (NCOA4), which functions as a selective cargo receptor, is a critical regulator of the particularly autophagic degradation of ferritin, a process known as ferritinophagy. Mechanistically, NCOA4-mediated ferritinophagy performs an increasingly vital role in the maintenance of intracellular iron homeostasis by promoting ferritin transport and iron release as needed. Ferritinophagy is not only involved in iron-dependent responses but also in the pathogenesis and progression of various human diseases, including metabolism-related, neurodegenerative, cardiovascular and infectious diseases. Therefore, ferritinophagy is of great importance in maintaining cell viability and function and represents a potential therapeutic target. Recent studies indicated that ferritinophagy regulates the signalling pathway associated with ferroptosis, a newly discovered type of cell death characterised by iron-dependent lipid peroxidation. Although accumulating evidence clearly demonstrates the importance of the interplay between dysfunction in iron metabolism and ferroptosis, a deeper understanding of the double-edged sword effect of ferritinophagy in ferroptosis has remained elusive. Details of the mechanisms underlying the ferritinophagy-ferroptosis axis in regulating relevant human diseases remain to be elucidated. In this review, we discuss the latest research findings regarding the mechanisms that regulate the biological function of NCOA4-mediated ferritinophagy and its contribution to the pathophysiology of ferroptosis. The important role of the ferritinophagy-ferroptosis axis in human diseases will be discussed in detail, highlighting the great potential of targeting ferritinophagy in the treatment of diseases.

Novel and experimental therapeutics for the management of motor and non-motor Parkinsonian symptoms

BACKGROUND  : Both motor and non-motor symptoms of Parkinson's disease (PD) have a substantial detrimental influence on the patient's quality of life. The most effective treatment remains oral levodopa. All currently known treatments just address the symptoms; they do not completely reverse the condition.

METHODOLOGY

In order to find literature on the creation of novel treatment agents and their efficacy for PD patients, we searched PubMed, Google Scholar, and other online libraries.

RESULTS

According to the most recent study on Parkinson's disease (PD), a great deal of work has been done in both the clinical and laboratory domains, and some current scientists have even been successful in developing novel therapies for PD patients.

CONCLUSION

The quality of life for PD patients has increased as a result of recent research, and numerous innovative medications are being developed for PD therapy. In the near future, we will see positive outcomes regarding PD treatment.

Glycative stress as a cause of macular degeneration

People are living longer and rates of age-related diseases such as age-related macular degeneration (AMD) are accelerating, placing enormous burdens on patients and health care systems. The quality of carbohydrate foods consumed by an individual impacts health. The glycemic index (GI) is a kinetic measure of the rate at which glucose arrives in the blood stream after consuming various carbohydrates. Consuming diets that favor slowly digested carbohydrates releases sugar into the bloodstream gradually after consuming a meal (low glycemic index). This is associated with reduced risk for major age-related diseases including AMD, cardiovascular disease, and diabetes. In comparison, consuming the same amounts of different carbohydrates in higher GI diets, releases glucose into the blood rapidly, causing glycative stress as well as accumulation of advanced glycation end products (AGEs). Such AGEs are cytotoxic by virtue of their forming abnormal proteins and protein aggregates, as well as inhibiting proteolytic and other protective pathways that might otherwise selectively recognize and remove toxic species. Using in vitro and animal models of glycative stress, we observed that consuming higher GI diets perturbs metabolism and the microbiome, resulting in a shift to more lipid-rich metabolomic profiles. Interactions between aging, diet, eye phenotypes and physiology were observed. A large body of laboratory animal and human clinical epidemiologic data indicates that consuming lower GI diets, or lower glycemia diets, is protective against features of early AMD (AMDf) in mice and AMD prevalence or AMD progression in humans. Drugs may be optimized to diminish the ravages of higher glycemic diets. Human trials are indicated to determine if AMD progression can be retarded using lower GI diets. Here we summarized the current knowledge regarding the pathological role of glycative stress in retinal dysfunction and how dietary strategies might diminish retinal disease.

Destabilization of fear memory by Rac1-driven engram-microglia communication in hippocampus

Rac1 is a key regulator of the cytoskeleton and neuronal plasticity, and is known to play a critical role in psychological and cognitive brain disorders. To elucidate the engram specific Rac1 signaling in fear memory, a doxycycline (Dox)-dependent robust activity marking (RAM) system was used to label dorsal dentate gyrus (DG) engram cells in mice during contextual fear conditioning. Rac1 mRNA and protein levels in DG engram cells were peaked at 24 h (day 1) after fear conditioning and were more abundant in the fear engram cells than in the non-engram cells. Optogenetic activation of Rac1 in a temporal manner in DG engram cells before memory retrieval decreased the freezing level in the fear context. Optogenetic activation of Rac1 increased autophagy protein 7 (ATG7) expression in the DG engram cells and activated DG microglia. Microglia-specific transcriptomics and fluorescence in situ hybridization revealed that overexpression of ATG7 in the fear engram cells upregulated the mRNA of Toll-like receptor TLR2/4 in DG microglia. Knockdown of microglial TLR2/4 rescued fear memory destabilization induced by ATG7 overexpression or Rac1 activation in DG engram cells. These results indicate that Rac1-driven communications between engram cells and microglia contributes to contextual fear memory destabilization, and is mediated by ATG7 and TLR2/4, and suggest a novel mechanistic framework for the cytoskeletal regulator in fear memory interference.

Impaired neuronal macroautophagy in the prelimbic cortex contributes to comorbid anxiety-like behaviors in rats with chronic neuropathic pain

A large proportion of patients with chronic pain experience co-morbid anxiety. The medial prefrontal cortex (mPFC) is proposed to underlie this comorbidity, but the molecular and neuronal mechanisms are not fully understood. Here, we reported that impaired neuronal macroautophagy in the prelimbic cortical (PrL) subregion of the mPFC paralleled the occurrence of anxiety-like behaviors in rats with chronic spared nerve injury (SNI). Intriguingly, such macroautophagy impairment was mainly observed in a FOS/c-Fos+ neuronal subpopulation in the PrL. Chemogenetic inactivation of this comorbid anxiety-related neuronal ensemble relieved pain-induced anxiety-like behaviors. Rescuing macroautophagy impairment in this neuronal ensemble relieved chronic pain-associated anxiety and mechanical allodynia and restored synaptic homeostasis at the molecular level. By contrast, artificial disruption of macroautophagy induced early-onset co-morbid anxiety in neuropathic rats, but not general anxiety in normal rats. Taken together, our work identifies causal linkage between PrL neuronal macroautophagy dysfunction and comorbid anxiety in neuropathic pain and provides novel insights into the role of PrL by differentiating its contribution in pain-induced comorbid anxiety from its modulation over general anxiety-like behaviors.Abbreviation: AAV: adeno-associated viruses; ACC: anterior cingulate cortex; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG12: autophagy related 12; CAMK2/CaMKII: calcium/calmodulin-dependent protein kinase II; CNO: clozapine-N-oxide; CQ: chloroquine; DIA: data independent acquisition; DIO: double floxed inverse orf; DLG4/PSD-95: discs large MAGUK scaffold protein 4; Dox: doxycycline; GABA: γ-aminobutyric acid; GFP: green fluorescent protein; GO: gene ontology; Gi: inhibitory guanine nucleotide-binding proteins; HsCHRM4/M4D: human cholinergic receptor muscarinic 4; HsSYN: human synapsin; KEGG: Kyoto encyclopedia of genes and genomes; LAMP1: lysosomal-associated membrane protein 1; LC3-II: PE conjugated microtubule-associated protein 1 light chain3; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; mPFC: medial prefrontal cortex; P2A: 2A self-cleaving peptide; PPI: protein-protein interaction networks; PrL: prelimbic cortex; RBFOX3/NeuN: RNA binding protein, fox-1 homolog (C. elegans) 3; rtTA: reverse tetracycline-transactivator; SDS-PAGE: sodium dodecylsulfate-polyacrylamide gel electrophoresis; SHANK3: SH3 and multiple ankyrin repeat domains 3; SLC1A1/EAAC1: solute carrier family 1 (neuronal/epithelial high affinity glutamate transporter, systemXag), member 1; SNAP23: synaptosomal-associated protein 23; SNI:spared nerve injury; SQSTM1/p62: sequestosome 1; SYT3: synaptotagmin 3; TRE: tetracycline-responsive element; TRE3G: third-generation tetracycline-responsive element.

Molecular cascade reveals sequential milestones underlying hippocampal neural stem cell development into an adult state

Quiescent adult neural stem cells (NSCs) in the mammalian brain arise from proliferating NSCs during development. Beyond acquisition of quiescence, an adult NSC hallmark, little is known about the process, milestones, and mechanisms underlying the transition of developmental NSCs to an adult NSC state. Here, we performed targeted single-cell RNA-seq analysis to reveal the molecular cascade underlying NSC development in the early postnatal mouse dentate gyrus. We identified two sequential steps, first a transition to quiescence followed by further maturation, each of which involved distinct changes in metabolic gene expression. Direct metabolic analysis uncovered distinct milestones, including an autophagy burst before NSC quiescence acquisition and cellular reactive oxygen species level elevation along NSC maturation. Functionally, autophagy is important for the NSC transition to quiescence during early postnatal development. Together, our study reveals a multi-step process with defined milestones underlying establishment of the adult NSC pool in the mammalian brain.

Comprehensive Overview of Alzheimer's Disease: Etiological Insights and Degradation Strategies

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder and affects millions of individuals globally. AD is associated with cognitive decline and memory loss that worsens with aging. A statistical report using U.S. data on AD estimates that approximately 6.9 million individuals suffer from AD, a number projected to surge to 13.8 million by 2060. Thus, there is a critical imperative to pinpoint and address AD and its hallmark tau protein aggregation early to prevent and manage its debilitating effects. Amyloid-β and tau proteins are primarily associated with the formation of plaques and neurofibril tangles in the brain. Current research efforts focus on degrading amyloid-β and tau or inhibiting their synthesis, particularly targeting APP processing and tau hyperphosphorylation, aiming to develop effective clinical interventions. However, navigating this intricate landscape requires ongoing studies and clinical trials to develop treatments that truly make a difference. Genome-wide association studies (GWASs) across various cohorts identified 40 loci and over 300 genes associated with AD. Despite this wealth of genetic data, much remains to be understood about the functions of these genes and their role in the disease process, prompting continued investigation. By delving deeper into these genetic associations, novel targets such as kinases, proteases, cytokines, and degradation pathways, offer new directions for drug discovery and therapeutic intervention in AD. This review delves into the intricate biological pathways disrupted in AD and identifies how genetic variations within these pathways could serve as potential targets for drug discovery and treatment strategies. Through a comprehensive understanding of the molecular underpinnings of AD, researchers aim to pave the way for more effective therapies that can alleviate the burden of this devastating disease.

Reviewing the Structure-Function Paradigm in Polyglutamine Disorders: A Synergistic Perspective on Theoretical and Experimental Approaches

Polyglutamine (polyQ) disorders are a group of neurodegenerative diseases characterized by the excessive expansion of CAG (cytosine, adenine, guanine) repeats within host proteins. The quest to unravel the complex diseases mechanism has led researchers to adopt both theoretical and experimental methods, each offering unique insights into the underlying pathogenesis. This review emphasizes the significance of combining multiple approaches in the study of polyQ disorders, focusing on the structure-function correlations and the relevance of polyQ-related protein dynamics in neurodegeneration. By integrating computational/theoretical predictions with experimental observations, one can establish robust structure-function correlations, aiding in the identification of key molecular targets for therapeutic interventions. PolyQ proteins' dynamics, influenced by their length and interactions with other molecular partners, play a pivotal role in the polyQ-related pathogenic cascade. Moreover, conformational dynamics of polyQ proteins can trigger aggregation, leading to toxic assembles that hinder proper cellular homeostasis. Understanding these intricacies offers new avenues for therapeutic strategies by fine-tuning polyQ kinetics, in order to prevent and control disease progression. Last but not least, this review highlights the importance of integrating multidisciplinary efforts to advancing research in this field, bringing us closer to the ultimate goal of finding effective treatments against polyQ disorders.

FABP5-binding lipids regulate autophagy in differentiated SH-SY5Y cells

The motor features of Parkinson's disease result from loss of dopaminergic neurons in the substantia nigra with autophagy dysfunction being closely linked to this disease. While a large body of work focusing on protein effectors of autophagy has been reported, regulation of autophagy by lipids has garnered far less attention. Therefore, we sought to identify endogenous lipid molecules that act as signaling mediators of autophagy in differentiated SH-SY5Y cells, a commonly used dopaminergic neuron-like cell model. In order to accomplish this goal, we assessed the role of a fatty acid-binding protein (FABP) family member on autophagy due to its function as an intracellular lipid chaperone. We focused specifically upon FABP5 due to its heightened expression in dopaminergic neurons within the substantia nigra and SH-SY5Y cells. Here, we report that knockdown of FABP5 resulted in suppression of autophagy in differentiated SH-SY5Y cells suggesting the possibility of an autophagic role for an interacting lipid. A lipidomic screen of FABP5-interacting lipids uncovered hits that include 5-oxo-eicosatetraenoic acid (5OE) and its precursor metabolite, arachidonic acid (AA). Additionally, other long-chain fatty acids were found to bind FABP5, such as stearic acid (SA), hydroxystearic acid (HSA), and palmitic acid (PA). The addition of 5OE, SA, and HSA but not AA or PA, led to potent inhibition of autophagy in SH-SY5Y cells. To identify potential molecular mechanisms for autophagy inhibition by these lipids, RNA-Seq was performed which revealed both shared and divergent signaling pathways between the lipid-treated groups. These findings suggest a role for these lipids in modulating autophagy through diverse signaling pathways and could represent novel therapeutic targets for Parkinson's disease.

Tau fibrils evade autophagy by excessive p62 coating and TAX1BP1 exclusion

The accumulation of protein aggregates is a hallmark of many diseases, including Alzheimer's disease. As a major pillar of the proteostasis network, autophagy mediates the degradation of protein aggregates. The autophagy cargo receptor p62 recognizes ubiquitin on proteins and cooperates with TAX1BP1 to recruit the autophagy machinery. Paradoxically, protein aggregates are not degraded in various diseases despite p62 association. Here, we reconstituted the recognition by the autophagy receptors of physiological and pathological Tau forms. Monomeric Tau recruits p62 and TAX1BP1 via the sequential actions of the chaperone and ubiquitylation machineries. In contrast, Tau fibrils from Alzheimer's disease brains are recognized by p62 but fail to recruit TAX1BP1. This failure is due to the masking of fibrils ubiquitin moieties by p62. Tau fibrils are resistant to deubiquitylation, and, thus, this nonproductive interaction of p62 with the fibrils is irreversible. Our results shed light on the mechanism underlying autophagy evasion by protein aggregates and their consequent accumulation in disease.

Mitigation of experimental ER stress and diabetes mellitus induced peripheral neuropathy by autophagy promoter, 6-BIO

Neuropathy occurs due to damage to the peripheral/central nervous system either due to injury, disease, or drug usage. Increased endoplasmic reticulum (ER) stress is observed in neuropathy. ER stress also leads to a block in autophagy amplifying neuropathic pain. 6-Bromoindirubin-3'-oxime (6-BIO) is an inhibitor of GSK-3β which suppresses mTOR activity thereby increasing autophagy. Tunicamycin (TM)-mediated ER stress and diabetic rat models were used to elucidate the role of ER stress and autophagy in mitigation of neuropathic pain by 6-BIO. Pain was assessed by behavioral studies in ER stressed/diabetic rats having neuropathy. Western blotting, RT-PCR, and fluorescence microscopy were used to assess the level of autophagy and ER stress after TM and 6-BIO treatment in SH-SY5Y neurons. Intraplantar injection of TM in rats led to peripheral neuropathy which was reduced upon 6-BIO injection. 6-BIO also reduced pain in animals exhibiting diabetic peripheral neuropathy. Modulation in the markers of autophagy (p-mTOR, LC-3, and SQSTM1/p62) shows that 6-BIO induces autophagolysosome formation post TM treatment. Concomitantly, 6-BIO reduces ER stress and c-Fos expression-a neuronal activity and pain marker. Alleviation of pain by the inhibition of ER stress and increased formation of autolysosomes by 6-BIO can be harnessed for treating peripheral neuropathy.

The role of autophagy in Parkinson's disease: a gender difference overview

Recent studies have demonstrated dysregulation of the autophagy pathway in patients with Parkinson's disease (PD) and in animal models of PD, highlighting its emerging role in disease. In particular, several studies indicate that autophagy, which is an essential degradative process for the damaged protein homeostasis and the management of cell balance, can manifest significant variations according to gender. While some evidence suggests increased autophagic activation in men with PD, women may have distinct regulatory patterns. In this review, we examined the existing literature on gender differences in PD-associated autophagic processes, focusing on the autophagy related proteins (ATGs) and leucine rich repeat kinase 2 (LRRK2) genes. Also, this review would suggest that an in-depth understanding of these gender differences in autophagic processes could open new perspectives for personalized therapeutic strategies, promoting more effective and targeted management of PD.

Immunological synapse formation between T regulatory cells and cancer-associated fibroblasts promotes tumour development

Cancer-associated fibroblasts (CAFs) have emerged as a dominant non-hematopoietic cell population in the tumour microenvironment, serving diverse functions in tumour progression. However, the mechanisms via which CAFs influence the anti-tumour immunity remain poorly understood. Here, using multiple tumour models and biopsies from cancer patients, we report that α-SMA+ CAFs can form immunological synapses with Foxp3+ regulatory T cells (Tregs) in tumours. Notably, α-SMA+ CAFs can phagocytose and process tumour antigens and exhibit a tolerogenic phenotype which instructs movement arrest, activation and proliferation in Tregs in an antigen-specific manner. Moreover, α-SMA+ CAFs display double-membrane structures resembling autophagosomes in their cytoplasm. Single-cell transcriptomic data showed an enrichment in autophagy and antigen processing/presentation pathways in α-SMA-expressing CAF clusters. Conditional knockout of Atg5 in α-SMA+ CAFs promoted inflammatory re-programming in CAFs, reduced Treg cell infiltration and attenuated tumour development. Overall, our findings reveal an immunosuppressive mechanism entailing the formation of synapses between α-SMA+ CAFs and Tregs in an autophagy-dependent manner.

The effect of N-acetylcysteine on the neurotoxicity of sevoflurane in developing hippocampus cells

Sevoflurane, a common pediatric anesthetic, has been linked to neurodegeneration, raising safety concerns. This study explored N-acetylcysteine's protective potential against sevoflurane-induced neurotoxicity in rat hippocampi. Four groups were examined: Control: Received 6 hours of 3 l/min gas (air and 30 % O2) and intraperitoneal saline. NAC: Received 6 hours of 3 l/min gas and 150 mg/kg NAC intraperitoneally. Sev: Exposed to 6 hours of 3 l/min gas and 3 % sevoflurane. Sev+NAC: Received 6 hours of 3 l/min gas, 3 % sevoflurane, and 150 mg/kg NAC. Protein levels of NRF-2, NLRP3, IL-1β, caspase-1, Beclin 1, p62, LC3A, and apoptosis markers were assessed. Sevoflurane and NAC alone reduced autophagy, while Sev+NAC group maintained autophagy levels. Sev group had elevated NRF-2, NLRP3, pNRF2, Caspase-1, and IL-1β, which were reduced in Sev+NAC. Apoptosis was higher in Sev, but Sev+NAC showed reduced apoptosis compared to the control. In summary, sevoflurane induced neurotoxicity in developing hippocampus, which was mitigated by N-acetylcysteine administration.

DACH1 attenuated PA-induced renal tubular injury through TLR4/MyD88/NF-κB and TGF-β/Smad signalling pathway

BACKGROUND

Palmitic acid (PA), the major saturated fatty acid in the blood, often induces the initiation and progression of diabetic kidney disease (DKD). However, the underlying mechanism remains unclear. DACH1 is an important regulator of kidney functions. Herein, we investigated the roles of DACH1 in PA-induced kidney injury.

METHODS

Clinical data from the NHANES database were subjected to analyse the association between serum PA (sPA), blood glucose and kidney function. Molecular docking of PA was performed with DACH1. Immunohistochemistry, cell viability, annexin V/7-AAD double staining, TUNEL assay, immunofluorescent staining, autophagic flux analysis, qRT-PCR and western blot were performed.

RESULTS

Clinical data confirmed that sPA was increased significantly in the pathoglycemia individuals compared with controls and correlated negatively with renal function. Our findings suggested that PA could dock with DACH1. DACH1 enhances cell viability by inhibiting apoptosis and attenuating autophagy blockage induced by PA. Furthermore, the results demonstrated that DACH1 ameliorated inflammation and fibrosis through TLR4/MyD88/NF-κB and TGF-β/Smad signalling pathway in PA-treated renal tubular epithelial cell line (HK-2).

CONCLUSIONS

This study proved that sPA presents a risk factor for kidney injuries and DACH1 might serve as a protective target against renal function deterioration in diabetic patients.

Neuroprotective effect of erythropoietin on anesthesia-induced neurotoxicity through the modulation of autophagy in Caenorhabditis elegans

BACKGROUND

The anti-oxidative, anti-inflammatory, and anti-apoptotic effects of erythropoietin may provide neuroprotective effects. Erythropoietin also modulates autophagy signaling that may play a role in anesthesia-induced neurotoxicity (AIN). Herein, we investigated whether AIN can be attenuated by the neuroprotective effect of erythropoietin in the Caenorhabditis elegans (C. elegans).

METHODS

Synchronized worms were divided into the control, Iso, EPO, and EPO-Iso groups. The chemotaxis index (CI) was evaluated when they reached the young adult stage. The lgg-1::GFP-positive puncta per seam cell were used to determine the autophagic events. The erythropoietin-mediated pathway of autophagy was determined by measuring the genetic expression level of let-363, bec-1, atg-7, atg-5, and lgg-3.

RESULTS

Increased lgg-1::GFP puncta were observed in the Iso, EPO, and EPO-Iso groups. In the Iso group, only the let-363 level decreased significantly as compared to that in the control group (P = 0.009). bec-1 (P < 0.001), atg-5 (P = 0.012), and lgg-3 (P < 0.001) were expressed significantly more in the EPO-Iso group than in the Iso groups. Repeated isoflurane exposure during development decreased the CI. Erythropoietin could restore the decreased CI by isoflurane significantly in the EPO-Iso group.

CONCLUSIONS

Erythropoietin showed neuroprotective effects against AIN and modulated the autophagic pathway in C. elegans. This experimental evidence of erythropoietin-related neuroprotection against AIN may be correlated with the induced autophagic degradation process that was sufficient for handling enhanced autophagy induction in erythropoietin-treated worms.