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Nature Communications Jan 2024Macroautophagy decreases with age, and this change is considered a hallmark of the aging process. It remains unknown whether mitophagy, the essential selective...
Macroautophagy decreases with age, and this change is considered a hallmark of the aging process. It remains unknown whether mitophagy, the essential selective autophagic degradation of mitochondria, also decreases with age. In our analysis of mitophagy in multiple organs in the mito-QC reporter mouse, mitophagy is either increased or unchanged in old versus young mice. Transcriptomic analysis shows marked upregulation of the type I interferon response in the retina of old mice, which correlates with increased levels of cytosolic mtDNA and activation of the cGAS/STING pathway. Crucially, these same alterations are replicated in primary human fibroblasts from elderly donors. In old mice, pharmacological induction of mitophagy with urolithin A attenuates cGAS/STING activation and ameliorates deterioration of neurological function. These findings point to mitophagy induction as a strategy to decrease age-associated inflammation and increase healthspan.
Topics: Humans; Mice; Animals; Aged; DNA, Mitochondrial; Mitophagy; Mitochondria; Inflammation; Nucleotidyltransferases; Aging
PubMed: 38280852
DOI: 10.1038/s41467-024-45044-1 -
International Journal of Molecular... Jan 2024IL-6 and IL-17 are paradoxical cytokines that progress inflammatory states in chronic diseases, including cancer. In lung cancer, their role has been elucidated to favor...
IL-6 and IL-17 are paradoxical cytokines that progress inflammatory states in chronic diseases, including cancer. In lung cancer, their role has been elucidated to favor cancer development by modulating signaling mechanisms critical to cellular growth. The intrinsic ability of these cytokines to influence macroautophagy is yet another reason to facilitate lung cancer. Here, we employed a systems immunology approach to discover the mechanistic role of these cytokines in cancer development. In a biological system, at later stages, the activation of NFkB stimulates immunosuppressive phenotypes to achieve tolerating effects in a transformed cell. We found that the upregulation of cytokines signaled M2 macrophages to modulate tumor responses through the activation of autophagic intermediates and inflammasome mediators. This caused immune perturbations in the tumor microenvironment, which were associated with cancer inflammation. To address these inflammatory states, we performed triggered event analysis to examine whether overexpressing immune effectors or downregulating immune suppressors may have an effect on cancer reversal. Interestingly, the inhibition of immune regulators opposed the model outcome to an increased immune response. Therefore, IL6-IL17-mediated regulation of lung cancer may address tumor malignancy and potentiate the development of newer therapeutics for NSCLC.
Topics: Humans; Interleukin-6; Interleukin-17; Carcinoma, Non-Small-Cell Lung; Lung Neoplasms; Cytokines; Tumor Microenvironment
PubMed: 38279220
DOI: 10.3390/ijms25021216 -
Frontiers in Cellular and Infection... 2023Anti-bacterial autophagy, also known as xenophagy, is a crucial innate immune process that helps maintain cellular homeostasis by targeting invading microbes. This...
Anti-bacterial autophagy, also known as xenophagy, is a crucial innate immune process that helps maintain cellular homeostasis by targeting invading microbes. This defense pathway is widely studied in the context of infections with mycobacteria, the causative agents of human tuberculosis and tuberculosis-like disease in animal models. Our previous work in a zebrafish tuberculosis model showed that host defense against (Mm) is impaired by deficiencies in xenophagy receptors, optineurin (Optn) or sequestome 1 (p62), and Damage-regulated autophagy modulator 1 (Dram1). However, the interdependency of these receptors and their interaction with Dram1 remained unknown. In the present study, we used single and double knockout zebrafish lines in combination with overexpression experiments. We show that Optn and p62 can compensate for the loss of each other's function, as their overexpression restores the infection susceptibility of the mutant phenotypes. Similarly, Dram1 can compensate for deficiencies in Optn and p62, and, vice versa, Optn and p62 compensate for the loss of Dram1, indicating that these xenophagy receptors and Dram1 do not rely on each other for host defense against Mm. In agreement, Dram1 overexpression in double mutants restored the interaction of autophagosome marker Lc3 with Mm. Finally, double mutants displayed more severe infection susceptibility than the single mutants. Taken together, these results suggest that Optn and p62 do not function downstream of each other in the anti-mycobacterial xenophagy pathway, and that the Dram1-mediated defense against Mm infection does not rely on specific xenophagy receptors.
Topics: Animals; Autophagy; Macroautophagy; Mycobacterium marinum; Tuberculosis; Zebrafish; Zebrafish Proteins
PubMed: 38264729
DOI: 10.3389/fcimb.2023.1331818 -
Acta Pharmaceutica Sinica. B Jan 2024Macroautophagy (referred to as autophagy hereafter) is a major intracellular lysosomal degradation pathway that is responsible for the degradation of misfolded/damaged...
Macroautophagy (referred to as autophagy hereafter) is a major intracellular lysosomal degradation pathway that is responsible for the degradation of misfolded/damaged proteins and organelles. Previous studies showed that autophagy protects against acetaminophen (APAP)-induced injury (AILI) selective removal of damaged mitochondria and APAP protein adducts. The lysosome is a critical organelle sitting at the end stage of autophagy for autophagic degradation fusion with autophagosomes. In the present study, we showed that transcription factor EB (TFEB), a master transcription factor for lysosomal biogenesis, was impaired by APAP resulting in decreased lysosomal biogenesis in mouse livers. Genetic loss-of and gain-of function of hepatic TFEB exacerbated or protected against AILI, respectively. Mechanistically, overexpression of TFEB increased clearance of APAP protein adducts and mitochondria biogenesis as well as SQSTM1/p62-dependent non-canonical nuclear factor erythroid 2-related factor 2 (NRF2) activation to protect against AILI. We also performed an unbiased cell-based imaging high-throughput chemical screening on TFEB and identified a group of TFEB agonists. Among these agonists, salinomycin, an anticoccidial and antibacterial agent, activated TFEB and protected against AILI in mice. In conclusion, genetic and pharmacological activating TFEB may be a promising approach for protecting against AILI.
PubMed: 38261809
DOI: 10.1016/j.apsb.2023.10.017 -
Frontiers in Cellular Neuroscience 2023Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by the depletion of the ubiquitously expressed survival motor neuron (SMN) protein. While... (Review)
Review
Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by the depletion of the ubiquitously expressed survival motor neuron (SMN) protein. While the genetic cause of SMA has been well documented, the exact mechanism(s) by which SMN depletion results in disease progression remain elusive. A wide body of evidence has highlighted the involvement and dysregulation of autophagy in SMA. Autophagy is a highly conserved lysosomal degradation process which is necessary for cellular homeostasis; defects in the autophagic machinery have been linked with a wide range of neurodegenerative disorders, including amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. The pathway is particularly known to prevent neurodegeneration and has been suggested to act as a neuroprotective factor, thus presenting an attractive target for novel therapies for SMA patients. In this review, (a) we provide for the first time a comprehensive summary of the perturbations in the autophagic networks that characterize SMA development, (b) highlight the autophagic regulators which may play a key role in SMA pathogenesis and (c) propose decreased autophagic flux as the causative agent underlying the autophagic dysregulation observed in these patients.
PubMed: 38259504
DOI: 10.3389/fncel.2023.1307636 -
Molecules (Basel, Switzerland) Jan 2024Autophagy is a pivotal biological process responsible for maintaining the homeostasis of intracellular organelles. Yet the molecular intricacies of peroxisomal autophagy...
Autophagy is a pivotal biological process responsible for maintaining the homeostasis of intracellular organelles. Yet the molecular intricacies of peroxisomal autophagy (pexophagy) remain largely elusive. From a ubiquitin-related chemical library for screening, we identified several inhibitors of the Von Hippel-Lindau (VHL) E3 ligase, including VH298, thereby serving as potent inducers of pexophagy. In this study, we observed that VH298 stimulates peroxisomal degradation by ATG5 dependently and escalates the ubiquitination of the peroxisomal membrane protein ABCD3. Interestingly, the ablation of NBR1 is similar to the curtailed peroxisomal degradation in VH298-treated cells. We also found that the pexophagy induced by VH298 is impeded upon the suppression of gene expression by the translation inhibitor cycloheximide. Beyond VHL inhibition, we discovered that roxadustat, a direct inhibitor of HIF-α prolyl hydroxylase, is also a potent inducer of pexophagy. Furthermore, we found that VH298-mediated pexophagy is blocked by silencing In conclusion, our findings suggest that VH298 promotes pexophagy by modulating VHL-mediated HIF-α transcriptional activity.
Topics: Humans; Macroautophagy; HeLa Cells; Autophagy; Homeostasis; Von Hippel-Lindau Tumor Suppressor Protein; Cyclopropanes; Pyrrolidines; Thiazoles
PubMed: 38257395
DOI: 10.3390/molecules29020482 -
Burns & Trauma 2024Refractory diabetic wounds are a common occurrence in patients with diabetes and epidermis-specific macroautophagy/autophagy impairment has been implicated in their...
BACKGROUND
Refractory diabetic wounds are a common occurrence in patients with diabetes and epidermis-specific macroautophagy/autophagy impairment has been implicated in their pathogenesis. Therefore, identifying and developing treatment strategies capable of normalizing epidermis-specific macroautophagy/autophagy could facilitate diabetic wound healing. The study aims to investigate the potential of bone marrow mesenchymal stem cell-derived exosomes (BMSC-exos) from hypoxic conditions as a treatment to normalize epidermis-specific autophagy for diabetic wound healing.
METHODS
We compared the effects of bone marrow mesenchymal stem cell (BMSC)-sourced exosomes (BMSC-Exos) from hypoxic conditions to those of BMSC in normoxic conditions (noBMSC-Exos). Our studies involved morphometric assessment of the exosomes, identification of the microRNA (miRNA) responsible for the effects, evaluation of keratinocyte functions and examination of effects of the exosomes on several molecules involved in the autophagy pathway such as microtubule-associated protein 1 light chain 3 beta, beclin 1, sequestosome 1, autophagy-related 5 and autophagy-related 5. The experiments used human BMSCs from the American Type Culture Collection, an mouse model of diabetes (db/db) to assess wound healing, as well as the human keratinocyte HaCaT cell line. In the methodology, the authors utilized an array of approaches that included electron microscopy, small interfering RNA (siRNA) studies, RNA hybridization, quantitative real-time reverse transcription PCR (qRT-PCR), the isolation, sequencing and differential expression of miRNAs, as well as the use of miR-4645-5p-specific knockdown with an inhibitor.
RESULTS
Hypoxia affected the release of exosomes from hypoxic BMSCs (hy-BMSCs) and influenced the size and morphology of the exosomes. Moreover, hyBMSC-Exo treatment markedly improved keratinocyte function, including keratinocyte autophagy, proliferation and migration. miRNA microarray and bioinformatics analysis showed that the target genes of the differentially expressed miRNAs were mainly enriched in 'autophagy' and 'process utilizing autophagic mechanism' in the 'biological process' category and miR-4645-5p as a major contributor to the pro-autophagy effect of hyBMSC-Exos. Moreover, mitogen-activated protein kinase-activated protein kinase 2 (MAPKAPK2) was identified as a potential target of exosomal miR-4645-5p; this was confirmed using a dual luciferase assay. Exosomal miR-4645-5p mediates the inactivation of the MAPKAPK2-induced AKT kinase group (comprising AKT1, AKT2, and AKT3), which in turn suppresses AKT-mTORC1 signaling, thereby facilitating miR-4645-5p-mediated autophagy.
CONCLUSIONS
Overall, the results of this study showed that hyBMSC-Exo-mediated transfer of miR-4645-5p inactivated MAPKAPK2-induced AKT-mTORC1 signaling in keratinocytes, which activated keratinocyte autophagy, proliferation and migration, resulting in diabetic wound healing in mice. Collectively, the findings could aid in the development of a novel therapeutic strategy for diabetic wounds.
PubMed: 38250706
DOI: 10.1093/burnst/tkad058 -
JOR Spine Mar 2024Intervertebral disc degeneration (IDD) is a leading contributor to low back pain (LBP). Autophagy, strongly activated by hypoxia and nutrient starvation, is a vital...
BACKGROUND
Intervertebral disc degeneration (IDD) is a leading contributor to low back pain (LBP). Autophagy, strongly activated by hypoxia and nutrient starvation, is a vital intracellular quality control process that removes damaged proteins and organelles to recycle them for cellular biosynthesis and energy production. While well-established as a major driver of many age-related diseases, autophagy dysregulation or deficiency has yet been confirmed to cause IDD.
METHODS
In vitro, rat nucleus pulposus (NP) cells treated with bafilomycin A1 to inhibit autophagy were assessed for glycosaminoglycan (GAG) content, proteoglycan synthesis, and cell viability. In vivo, a transgenic strain (; ) mice were successfully generated to inhibit autophagy primarily in NP tissues. ; mouse intervertebral discs (IVDs) were evaluated for biomarkers for apoptosis and cellular senescence, aggrecan content, and histological changes up to 12 months of age.
RESULTS
Here, we demonstrated inhibition of autophagy by bafilomycin produced IDD features in the rat NP cells, including increased apoptosis and cellular senescence ( ) and decreased expression of disc matrix genes and . H&E histologic staining showed significant but modest degenerative changes in NP tissue of mice compared to controls at 6 and 12 months of age. Intriguingly, 12-month-old mice did not display increased loss of NP proteoglycan. Moreover, markers of apoptosis (cleaved caspase-3, TUNEL), and cellular senescence (p53, IL-1β, TNF-α) were not affected in 12-month-old mice compared to controls. However, and gene expression were upregulated in NP tissue of 12-month-old mice compared to controls, suggesting -mediated cellular senescence resulted from NP-targeted knockout might contribute to the observed histological changes.
CONCLUSION
The absence of overt IDD features from disrupting -mediated macroautophagy in NP tissue implicates other compensatory mechanisms, highlighting additional research needed to elucidate the complex biology of autophagy in regulating age-dependent IDD.
PubMed: 38234974
DOI: 10.1002/jsp2.1286 -
Cells Jan 2024Autophagy is a major degradative pathway that plays a key role in sustaining cell homeostasis, integrity, and physiological functions. Macroautophagy, which ensures the... (Review)
Review
Autophagy is a major degradative pathway that plays a key role in sustaining cell homeostasis, integrity, and physiological functions. Macroautophagy, which ensures the clearance of cytoplasmic components engulfed in a double-membrane autophagosome that fuses with lysosomes, is orchestrated by a complex cascade of events. Autophagy has a particularly strong impact on the nervous system, and mutations in core components cause numerous neurological diseases. We first review the regulation of autophagy, from autophagosome biogenesis to lysosomal degradation and associated neurodevelopmental/neurodegenerative disorders. We then describe how this process is specifically regulated in the axon and in the somatodendritic compartment and how it is altered in diseases. In particular, we present the neuronal specificities of autophagy, with the spatial control of autophagosome biogenesis, the close relationship of maturation with axonal transport, and the regulation by synaptic activity. Finally, we discuss the physiological functions of autophagy in the nervous system, during development and in adulthood.
Topics: Autophagy; Macroautophagy; Autophagosomes; Axonal Transport; Lysosomes
PubMed: 38201307
DOI: 10.3390/cells13010103 -
Scientific Reports Jan 2024Neuropsychiatric and neurodegenerative disorders are correlated with cellular stress. Macroautophagy (autophagy) may represent an important protective pathway to...
Neuropsychiatric and neurodegenerative disorders are correlated with cellular stress. Macroautophagy (autophagy) may represent an important protective pathway to maintain cellular homeostasis and functionality, as it targets cytoplasmic components to lysosomes for degradation and recycling. Given recent evidence that some novel psychiatric treatments, such as the neuroactive steroid (NAS) allopregnanolone (AlloP, brexanolone), may induce autophagy, we stably transfected human embryonic kidney 293 (HEK) cells with a ratiometric fluorescent probe to assay NAS effects on autophagy. We hypothesized that NAS may modulate autophagy in part by the ability of uncharged NAS to readily permeate membranes. Microscopy revealed a weak effect of AlloP on autophagic flux compared with the positive control treatment of Torin1. In high-throughput microplate experiments, we found that autophagy induction was more robust in early passages of HEK cells. Despite limiting studies to early passages for maximum sensitivity, a range of NAS structures failed to reliably induce autophagy or interact with Torin1 or starvation effects. To probe NAS in a system where AlloP effects have been shown previously, we surveyed astrocytes and again saw minimal autophagy induction by AlloP. Combined with other published results, our results suggest that NAS may modulate autophagy in a cell-specific or context-specific manner. Although there is merit to cell lines as a screening tool, future studies may require assaying NAS in cells from brain regions involved in neuropsychiatric disorders.
Topics: Humans; Neurosteroids; Autophagy; Macroautophagy; Kidney; Lysosomes
PubMed: 38200205
DOI: 10.1038/s41598-024-51582-x