The pH-sensitive translocation of V-ATPase in the small airway of cystic fibrosis pigs.

In contrast to pig large airways, the pH of airway surface liquid (ASL) in pig small airways is regulated by CFTR mediated HCO-3 secretion and the vacuolar-type H+ ATPase (V-ATPase) proton secretion. We hypothesized that in Cystic Fibrosis (CF), the ASL pH of small airways is acidic, and the V-ATPase is internalized. We quantified proton secretion during the addition of an alkaline test solutions by measuring changes in a pH dependent fluorescent dye generated by porcine small airway epithelia in the absence and presence of bafilomycin A1. The pH-dependent translocation of V-ATPase in ex vivo and in vivo preparations was measured using immunolocalization of V-ATPase. We found that bafilomycin sensitive proton secretion stopped when the ASL pH was less than 7.10. In non-CF pigs and mice, we found that V-ATPase was localized in the apical membrane, and internalized when the lungs were instilled with a pH 6.8 solution.Studies where we immediately fixed lungs from pigs revealed apical V-ATPase detection in non-CF piglets and less apical detection in CF piglets. Our data suggest that V-ATPase in small airways is internalized when the ASL pH is acidic. The decrease in apical localization of V-ATPase in CF pigs is consistent with an acidic ASL pH.

Discovery of the Chlorinated and Ammoniated Derivatives of Vanillin as Potential Insecticidal Candidates Targeting V-ATPase: Structure-Based Virtual Screening, Synthesis, and Bioassay.

Vacuolar-type H+-ATPases (V-ATPases) play a crucial role in the life cycle of agricultural pests and represent a promising target for the development of novel insecticides. In this study, S18, a derivative of vanillin acquired from Specs database using a structure-based virtual screening methodology, was first identified as a V-ATPase inhibitor. It binds to subunit A of the enzyme with a Kd of 1 nM and exhibits insecticidal activity against M. separata. Subsequently, using S18 as the lead compound, a new series of vanillin derivatives were rationally designed and efficiently synthesized. and their biological activities were assessed. Among them, compound 3b-03 showed the strongest insecticidal activity against M. separata by effectively targeting the V-ATPase subunit A with Kd of 0.803 µM. Isothermal titration calorimetric measurements and docking results provided insights into its interaction with subunit A of V-ATPase, which could facilitate future research aimed at the development of novel chemical insecticides.

The V-ATPase/ATG16L1 axis is controlled by the V1H subunit.

Defects in organellar acidification indicate compromised or infected compartments. Recruitment of the autophagy-related ATG16L1 complex to pathologically neutralized organelles targets ubiquitin-like ATG8 molecules to perturbed membranes. How this process is coupled to proton gradient disruption is unclear. Here, we reveal that the V1H subunit of the vacuolar ATPase (V-ATPase) proton pump binds directly to ATG16L1. The V1H/ATG16L1 interaction only occurs within fully assembled V-ATPases, allowing ATG16L1 recruitment to be coupled to increased V-ATPase assembly following organelle neutralization. Cells lacking V1H fail to target ATG8s during influenza infection or after activation of the immune receptor stimulator of interferon genes (STING). We identify a loop within V1H that mediates ATG16L1 binding. A neuronal V1H isoform lacks this loop and is associated with attenuated ATG8 targeting in response to ionophores in primary murine and human iPSC-derived neurons. Thus, V1H controls ATG16L1 recruitment following proton gradient dissipation, suggesting that the V-ATPase acts as a cell-intrinsic damage sensor.

Conjugation of ATG8s to single membranes at a glance.

Autophagy refers to a set of degradative mechanisms whereby cytoplasmic contents are targeted to the lysosome. This is best described for macroautophagy, where a double-membrane compartment (autophagosome) is generated to engulf cytoplasmic contents. Autophagosomes are decorated with ubiquitin-like ATG8 molecules (ATG8s), which are recruited through covalent lipidation, catalysed by the E3-ligase-like ATG16L1 complex. LC3 proteins are ATG8 family members that are often used as a marker for autophagosomes. In contrast to canonical macroautophagy, conjugation of ATG8s to single membranes (CASM) describes a group of non-canonical autophagy processes in which ATG8s are targeted to pre-existing single-membrane compartments. CASM occurs in response to disrupted intracellular pH gradients, when the V-ATPase proton pump recruits ATG16L1 in a process called V-ATPase-ATG16L1-induced LC3 lipidation (VAIL). Recent work has demonstrated a parallel, alternative axis for CASM induction, triggered when the membrane recruitment factor TECPR1 recognises sphingomyelin exposed on the cytosolic face of a membrane and forms an alternative E3-ligase-like complex. This sphingomyelin-TECPR1-induced LC3 lipidation (STIL) is independent of the V-ATPase and ATG16L1. In light of these discoveries, this Cell Science at a Glance article summarises these two mechanisms of CASM to highlight how they differ from canonical macroautophagy, and from each other.

Vacuolar H+-ATPase determines daughter cell fates through asymmetric segregation of the nucleosome remodeling and deacetylase complex.

Asymmetric cell divisions (ACDs) generate two daughter cells with identical genetic information but distinct cell fates through epigenetic mechanisms. However, the process of partitioning different epigenetic information into daughter cells remains unclear. Here, we demonstrate that the nucleosome remodeling and deacetylase (NuRD) complex is asymmetrically segregated into the surviving daughter cell rather than the apoptotic one during ACDs in Caenorhabditis elegans. The absence of NuRD triggers apoptosis via the EGL-1-CED-9-CED-4-CED-3 pathway, while an ectopic gain of NuRD enables apoptotic daughter cells to survive. We identify the vacuolar H+-adenosine triphosphatase (V-ATPase) complex as a crucial regulator of NuRD's asymmetric segregation. V-ATPase interacts with NuRD and is asymmetrically segregated into the surviving daughter cell. Inhibition of V-ATPase disrupts cytosolic pH asymmetry and NuRD asymmetry. We suggest that asymmetric segregation of V-ATPase may cause distinct acidification levels in the two daughter cells, enabling asymmetric epigenetic inheritance that specifies their respective life-versus-death fates.

Dmxl1 Is an Essential Mammalian Gene that Is Required for V-ATPase Assembly and Function In Vivo.

The proton pumping V-ATPase drives essential biological processes, such as acidification of intracellular organelles. Critically, the V-ATPase domains, V1 and VO, must assemble to produce a functional holoenzyme. V-ATPase dysfunction results in cancer, neurodegeneration, and diabetes, as well as systemic acidosis caused by reduced activity of proton-secreting kidney intercalated cells (ICs). However, little is known about the molecular regulation of V-ATPase in mammals. We identified a novel interactor of the mammalian V-ATPase, Drosophila melanogaster X chromosomal gene-like 1 (Dmxl1), aka Rabconnectin-3A. The yeast homologue of Dmxl1, Rav1p, is part of a complex that catalyzes the reversible assembly of the domains. We, therefore,hypothesized that Dmxl1 is a mammalian V-ATPase assembly factor. Here, we generated kidney IC-specific Dmxl1 knockout (KO) mice, which had high urine pH, like B1 V-ATPase KO mice, suggesting impaired V-ATPase function. Western blotting showed decreased B1 expression and B1 (V1) and a4 (VO) subunits were more intracellular and less colocalized in Dmxl1 KO ICs. In parallel, subcellular fractionation revealed less V1 associated B1 in the membrane fraction of KO cells relative to the cytosol. Furthermore, a proximity ligation assay performed using probes against B1 and a4 V-ATPase subunits also revealed decreased association. We propose that loss of Dmxl1 reduces V-ATPase holoenzyme assembly, thereby inhibiting proton pumping function. Dmxl1 may recruit the V1 domain to the membrane and facilitate assembly with the VO domain and in its absence V1 may be targeted for degradation. We conclude that Dmxl1 is a bona fide mammalian V-ATPase assembly factor.

HPS6 Deficiency Leads to Reduced V-ATPase and Impaired Biogenesis of Lamellar Bodies in Alveolar Type II Cells.

Lamellar body (LB) is a tissue-specific lysosome-related organelle in type II alveolar cells, which is the main site for the synthesis, storage and secretion of pulmonary surfactants. Defects in pulmonary surfactants lead to a variety of respiratory and immune-related disorders. LB biogenesis is closely related to its function, but the underlying regulatory mechanism is largely unclear. Here, we found that deficiency of HPS6, a subunit of BLOC-2 (biogenesis of lysosome-related organelles complex-2), led to the reduction of the steady-state level of V-ATPase and the increase of luminal pH of LB. Furthermore, we observed increased LB size, accumulated surfactant proteins, and altered lipid profiling of lung tissue and bronchoalveolar lavage fluid due to HPS6 deficiency. These findings suggest that HPS6 regulates the distribution of V-ATPase on LBs to maintain its luminal acidity and LB homeostasis. This may provide new insights into the LB pathology.

Curbing Breast Cancer by Altering V-ATPase Action on F-Actin, Heterochromatin, ETV7 and mTORC2 Signaling.

BACKGROUND/AIMS: Motivated by the vacuolar proton pump's importance in cancer, we investigate the effects of proton pump inhibition on breast cancer cell migration and proliferation, F-actin polymerization, lamin A/C, heterochromatin, and ETV7 expressions, nuclear size and shape, and AKT/mTOR signaling. METHODS: Lowly metastatic MCF7 and highly metastatic MDA-MB-231 breast cancer cells were treated with 120 nM of proton pump inhibitor Bafilomycin A1 for 24 hours. Cell migration was studied with wound- scratch assays, ATP levels with a chemiluminescent assay; cell proliferation was quantified by a cell area expansion assay. Nuclear size and shape were determined using DAPI nuclear stain and fluorescence microscopy. The levels of F-actin, lamin A/C, heterochromatin, and ETV7 were quantified using both immunocytochemistry and western blots; p-mTORC1, p-mTORC2, mTOR, p-AKT, and AKT were measured by western blots. RESULTS: We reveal that proton pump inhibition reduces F-actin polymerization, cell migration, proliferation, and increases heterochromatin in both lowly and highly metastatic cells. Surprisingly, Bafilomycin decreases lamin A/C in both cell lines. Inhibition has different effects on ETV7 expression in lowly and highly metastatic cells, as well as nuclear area, perimeter, and circularity. Bafilomycin also significantly decreases p-mTORC1, p-MTORC2, and MTOR expression in both cell lines, whereas it significantly decreases p-AKT in lowly metastatic cells and surprisingly significantly increases p-AKT in highly metastatic cells. Our proton pump inhibition protocol reduces V-ATPase levels (~25%) within three hours. V-ATPase levels vary in time for both control and inhibited cells, and inhibition reduces cellular ATP. CONCLUSION: Proton pumps promote F-actin polymerization and decrease heterochromatin, facilitating invasion. These pumps also upregulate both mTORC1 and mTORC2, thus highlighting the relevance of vacuolar proton pumps as metastatic cancer targets.

The different roles of V-ATPase a subunits in phagocytosis/endocytosis and autophagy.

Microglia are specialized macrophages responsible for the clearance of dead neurons and pathogens by phagocytosis and degradation. The degradation requires phagosome maturation and acidification provided by the vesicular- or vacuolar-type H+-translocating adenosine triphosphatase (V-ATPase), which is composed of the cytoplasmic V1 domain and the membrane-embedded Vo domain. The V-ATPase a subunit, an integral part of the Vo domain, has four isoforms in mammals. The functions of different isoforms on phagosome maturation in different cells/species remain controversial. Here we show that mutations of both the V-ATPase Atp6v0a1 and Tcirg1b/Atp6v0a3 subunits lead to the accumulation of phagosomes in zebrafish microglia. However, their mechanisms are different. The V-ATPase Atp6v0a1 subunit is mainly distributed in early and late phagosomes. Defects of this subunit lead to a defective transition from early phagosomes to late phagosomes. In contrast, The V-ATPase Tcirg1b/Atp6v0a3 subunit is primarily located on lysosomes and regulates late phagosome-lysosomal fusion. Defective Tcirg1b/Atp6v0a3, but not Atp6v0a1 subunit leads to reduced acidification and impaired macroautophagy/autophagy in microglia. We further showed that ATP6V0A1/a1 and TCIRG1/a3 subunits in mouse macrophages preferentially located in endosomes and lysosomes, respectively. Blocking these subunits disrupted early-to-late endosome transition and endosome-to-lysosome fusion, respectively. Taken together, our results highlight the essential and conserved roles played by different V-ATPase subunits in multiple steps of phagocytosis and endocytosis across various species.Abbrevations: Apoe: apolipoprotein E; ANXA5/annexin V: annexin A5; ATP6V0A1/a1: ATPase H+-transporting V0 subunit a1; ATP6V0A2/a2: ATPase H+-transporting V0 subunit a2; ATP6V0A4/a4: ATPase H+-transporting V0 subunit a4; dpf: days post-fertilization; EEA1: early endosome antigen 1; HOPS: homotypic fusion and protein sorting; LAMP1: lysosomal associated membrane protein 1; Lcp1: lymphocyte cytosolic protein 1 (L-plastin); Map1lc3/Lc3: microtubule-associated protein 1 light chain 3; NR: neutral red; PBS: phosphate-buffered saline; PtdIns: phosphatidylinositol; PtdIns3P: phosphatidylinositol-3-phosphate; PtdIns(3,5)P2: phosphatidylinositol (3,5)-bisphosphate; RAB4: RAB4, member RAS oncogene family; RAB5: RAB5, member RAS oncogene family; RAB7: RAB7, member RAS oncogene family; TCIRG1/Atp6v0a3/a3: T cell immune regulator 1, ATPase H+-transporting V0 subunit a3; V-ATPase: vacuolar-type H+-translocating adenosine triphosphatase; Xla.Tubb2b/NBT: tubulin beta 2B class IIb.

Acidic Nanoparticles Restore Lysosomal Acidification and Rescue Metabolic Dysfunction in Pancreatic ß-Cells under Lipotoxic Conditions.

Type 2 diabetes (T2D), a prevalent metabolic disorder lacking effective treatments, is associated with lysosomal acidification dysfunction, as well as autophagic and mitochondrial impairments. Here, we report a series of biodegradable poly(butylene tetrafluorosuccinate-co-succinate) polyesters, comprising a 1,4-butanediol linker and varying ratios of tetrafluorosuccinic acid (TFSA) and succinic acid as components, to engineer lysosome-acidifying nanoparticles (NPs). The synthesized NPs are spherical with diameters of ≈100 nm and have low polydispersity and good stability. Notably, TFSA NPs, which are composed entirely of TFSA, exhibit the strongest degradation capability and superior acidifying properties. We further reveal significant downregulation of lysosomal vacuolar (H+)-ATPase subunits, which are responsible for maintaining lysosomal acidification, in human T2D pancreatic islets, INS-1 ß-cells under chronic lipotoxic conditions, and pancreatic tissues of high-fat-diet (HFD) mice. Treatment with TFSA NPs restores lysosomal acidification, autophagic function, and mitochondrial activity, thereby improving the pancreatic function in INS-1 cells and HFD mice with lipid overload. Importantly, the administration of TFSA NPs to HFD mice reduces insulin resistance and improves glucose clearance. These findings highlight the therapeutic potential of lysosome-acidifying TFSA NPs for T2D.

ATP6V1A is required for synaptic rearrangements and plasticity in murine hippocampal neurons.

AIM: Understanding the physiological role of ATP6V1A, a component of the cytosolic V1 domain of the proton pump vacuolar ATPase, in regulating neuronal development and function. METHODS: Modeling loss of function of Atp6v1a in primary murine hippocampal neurons and studying neuronal morphology and function by immunoimaging, electrophysiological recordings and electron microscopy. RESULTS: Atp6v1a depletion affects neurite elongation, stabilization, and function of excitatory synapses and prevents synaptic rearrangement upon induction of plasticity. These phenotypes are due to an overall decreased expression of the V1 subunits, that leads to impairment of lysosomal pH-regulation and autophagy progression with accumulation of aberrant lysosomes at neuronal soma and of enlarged vacuoles at synaptic boutons. CONCLUSIONS: These data suggest a physiological role of ATP6V1A in the surveillance of synaptic integrity and plasticity and highlight the pathophysiological significance of ATP6V1A loss in the alteration of synaptic function that is associated with neurodevelopmental and neurodegenerative diseases. The data further support the pivotal involvement of lysosomal function and autophagy flux in maintaining proper synaptic connectivity and adaptive neuronal properties.

Acidification of α-granules in megakaryocytes by vacuolar-type adenosine triphosphatase is essential for organelle biogenesis.

BACKGROUND: Platelets coordinate blood coagulation at sites of vascular injury and play fundamental roles in a wide variety of (patho)physiological processes. Key to many platelet functions is the transport and secretion of proteins packaged within α-granules, organelles produced by platelet precursor megakaryocytes. Prominent among α-granule cargo are fibrinogen endocytosed from plasma and endogenously synthesized von Willebrand factor. These and other proteins are known to require acidic pH for stable packaging. Luminal acidity has been confirmed for mature α-granules isolated from platelets, but direct measurement of megakaryocyte granule acidity has not been reported. OBJECTIVES: To determine the luminal pH of α-granules and their precursors in megakaryocytes and assess the requirement of vacuolar-type adenosine triphosphatase (V-ATPase) activity to establish and maintain the luminal acidity and integrity of these organelles. METHODS: Cresyl violet staining was used to detect acidic granules in megakaryocytes. Endocytosis of fibrinogen tagged with the pH-sensitive fluorescent dye fluorescein isothiocyanate was used to load a subset of these organelles. Ratiometric fluorescence analysis was used to determine their luminal pH. RESULTS: We show that most of the acidic granules detected in megakaryocytes appear to be α-granules/precursors, for which we established a median luminal pH of 5.2 (IQR, 5.0-5.5). Inhibition of megakaryocyte V-ATPase activity led to enlargement of cargo-containing compartments detected by fluorescence microscopy and electron microscopy. CONCLUSION: These observations reveal that V-ATPase activity is required to establish and maintain a luminal acidic pH in megakaryocyte α-granules/precursors, confirming its importance for stable packaging of cargo proteins such as von Willebrand factor.

ATP6V1B1 regulates ovarian cancer progression and cisplatin sensitivity through the mTOR/autophagy pathway.

Early detection and effective chemotherapy for ovarian cancer, a serious gynecological malignancy, require further progress. This study aimed to investigate the molecular mechanism of ATPase H+-Transporting V1 Subunit B1 (ATP6V1B1) in ovarian cancer development and chemoresistance. Our data show that ATP6V1B1 is upregulated in ovarian cancer and correlated with decreased progression-free survival. Gain- and loss-of-function experiments demonstrated that ATP6V1B1 promotes the proliferation, migration, and invasion of ovarian cancer cells in vitro, while ATP6V1B1 knockout inhibits tumor growth in vivo. In addition, knocking down ATP6V1B1 increases the sensitivity of ovarian cancer cells to cisplatin. Mechanistic studies showed that ATP6V1B1 regulates the activation of the mTOR/autophagy pathway. Overall, our study confirmed the oncogenic role of ATP6V1B1 in ovarian cancer and revealed that ATP6V1B1 promotes ovarian cancer progression via the mTOR/autophagy axis.

Plasma exosomes impair microglial degradation of α-synuclein through V-ATPase subunit V1G1.

INTRODUCTION: Microglia are the main phagocytes in the brain and can induce neuroinflammation. Moreover, they are critical to alpha-synuclein (α-syn) aggregation and propagation. Plasma exosomes derived from patients diagnosed with Parkinson's disease (PD-exo) reportedly evoked α-syn aggregation and inflammation in microglia. In turn, microglia internalized and released exosomal α-syn, enhancing α-syn propagation. However, the specific mechanism through which PD-exo influences α-syn degradation remains unknown. METHODS: Exosomes were extracted from the plasma of patients with PD by differential ultracentrifugation, analyzed using electron microscopy (EM) and nanoparticle flow cytometry, and stereotaxically injected into the unilateral striatum of the mice. Transmission EM was employed to visualize lysosomes and autophagosomes in BV2 cells, and lysosome pH was measured with LysoSensor Yellow/Blue DND-160. Cathepsin B and D, lysosomal-associated membrane protein 1 (LAMP1), ATP6V1G1, tumor susceptibility gene 101 protein, calnexin, α-syn, ionized calcium binding adaptor molecule 1, and NLR family pyrin domain containing 3 were evaluated using quantitative polymerase chain reaction or western blotting, and α-syn, LAMP1, and ATP6V1G1 were also observed by immunofluorescence. Small interfering ribonucleic acid against V1G1 was transfected into BV2 cells and primary microglia using Lipofectamine® 3000. A PD mouse model was established via injection with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into mice. A lentiviral-mediated strategy to overexpress ATP6V1G1 in the brain of MPTP-treated mice was employed. Motor coordination was assessed using rotarod and pole tests, and neurodegeneration in the mouse substantia nigra and striatum tissues was determined using immunofluorescence histochemical and western blotting of tyrosine hydroxylase. RESULTS: PD-exo decreased the expression of V1G1, responsible for the acidification of intra- and extracellular milieu. This impairment of lysosomal acidification resulted in the accumulation of abnormally swollen lysosomes and decreased lysosomal enzyme activities, impairing lysosomal protein degradation and causing α-syn accumulation. Additionally, V1G1 overexpression conferred the mice neuroprotection during MPTP exposure. CONCLUSION: Pathogenic protein accumulation is a key feature of PD, and compromised V-type ATPase dysfunction might participate in PD pathogenesis. Moreover, V1G1 overexpression protects against neuronal toxicity in an MPTP-based PD mouse model, which may provide opportunities to develop novel therapeutic interventions for PD treatment.

V-ATPase B2 promotes microglial phagocytosis of myelin debris by inactivating the MAPK signaling pathway.

Microglial phagocytosis of myelin debris is a crucial process for promoting myelin regeneration in conditions such as multiple sclerosis (MS). Vacuolar-ATPase B2 (V-ATPase B2) has been implicated in various cellular processes, but its role in microglial phagocytosis and its potential impact on MS-related responses remain unclear. In this study, we employed BV-2 murine microglial cells to investigate the influence of V-ATPase B2 on the phagocytosis of myelin debris by microglia. The results revealed that V-ATPase B2 expression increased in response to myelin debris exposure. Overexpression of V-ATPase B2 significantly enhanced BV-2 phagocytosis of myelin debris. Additionally, V-ATPase B2 overexpression shifted microglial polarization towards an anti-inflammatory M2 phenotype, coupled with decreased lysosomal pH and enhanced lysosome degradation capacity. Moreover, endoplasmic reticulum (ER) stress inhibitor, 4-PBA, reversed the effects of V-ATPase B2 silencing on ER stress, M2 polarization, and lysosomal degradation of BV-2 cells. The MAPK pathway was inhibited upon V-ATPase B2 overexpression, contributing to heightened myelin debris clearance by BV-2 cells. Notably, MAPK pathway inhibition partially attenuated the inhibitory effects of V-ATPase B2 knockdown on myelin debris clearance. In conclusion, our findings reveal a pivotal role for V-ATPase B2 in promoting microglial phagocytosis of myelin debris by regulating microglial polarization and lysosomal function via the MAPK signaling pathway, suggesting that targeting V-ATPase B2 may hold therapeutic potential for enhancing myelin debris clearance and modulating microglial responses in MS and related neuroinflammatory disorders.

Human V-ATPase function is positively and negatively regulated by TLDc proteins.

Proteins that contain a highly conserved TLDc domain (Tre2/Bub2/Cdc16 LysM domain catalytic) offer protection against oxidative stress and are widely implicated in neurological health and disease. How this family of proteins exerts their function, however, is poorly understood. We have recently found that the yeast TLDc protein, Oxr1p, inhibits the proton pumping vacuolar ATPase (V-ATPase) by inducing disassembly of the pump. While loss of TLDc protein function in mammals shares disease phenotypes with V-ATPase defects, whether TLDc proteins impact human V-ATPase activity directly is unclear. Here we examine the effects of five human TLDc proteins, TLDC2, NCOA7, OXR1, TBC1D24, and mEAK7 on the activity of the human V-ATPase. We find that while TLDC2, TBC1D24, and the TLDc domains of OXR1 and NCOA7 inhibit V-ATPase by inducing enzyme disassembly, mEAK7 activates the pump. The data thus shed new light both on mammalian TLDc protein function and V-ATPase regulation.

Lysosomal dysfunction by inactivation of V-ATPase drives innate immune response in C. elegans.

Pathogens target vacuolar ATPase (V-ATPase) to inhibit lysosomal acidification or lysosomal fusion, causing lysosomal dysfunction. However, it remains unknown whether cells can detect dysfunctional lysosomes and initiate an immune response. In this study, we discover that dysfunction of lysosomes caused by inactivation of V-ATPase enhances innate immunity against bacterial infections. We find that lysosomal V-ATPase interacts with DVE-1, whose nuclear localization serves as a proxy for the induction of mitochondrial unfolded protein response (UPRmt). The inactivation of V-ATPase promotes the nuclear localization of DVE-1, activating UPRmt and inducing downstream immune response genes. Furthermore, pathogen resistance conferred by inactivation of V-ATPase requires dve-1 and its downstream immune effectors. Interestingly, animals grow slower after vha RNAi, suggesting that the vha-RNAi-induced immune response costs the most energy through activation of DVE-1, which trades off with growth. This study reveals how dysfunctional lysosomes can trigger an immune response, emphasizing the importance of conserving energy during immune defense.

Epileptic encephalopathies and progressive neurodegeneration.

Developmental encephalopathies (DE), epileptic encephalopathies (EE) and developmental and epileptic encephalopathies (DEE) are overlapping neurodevelopmental disorders characterized by early-onset, often severe epileptic seizures, developmental delay, or regression and have multiple etiologies. Classical nosology in child neurology distinguished progressive and nonprogressive conditions. A progressive course with global cognitive worsening in DEE is usually attributed to severe seizures and electroencephalographic abnormalities whose deleterious effects interfere with developmental processes both in an apparently healthy brain and in an anatomically compromised one. Next generation sequencing and functional studies have helped identifying and characterizing clinical conditions, each with a broad spectrum of clinical and anatomic severity corresponding to a variable level of neurodegeneration, such that both a rapidly progressive course and considerably milder phenotypes with no obvious deterioration can be configured with mutations in the same gene. In this mini review, we present examples of genetic DEE that draw connections between neurodevelopmental and neurodegenerative disorders.

Increased V-ATPase activity can lead to chemo-resistance in oral squamous cell carcinoma via autophagy induction: new insights.

Oral squamous cell carcinoma (OSCC) is a cancer type with a high rate of recurrence and a poor prognosis. Tumor chemo-resistance remains an issue for OSCC patients despite the availability of multimodal therapy options, which causes an increase in tumor invasiveness. Vacuolar ATPase (V-ATPase), appears to be one of the most significant molecules implicated in MDR in tumors like OSCC. It is primarily responsible for controlling the acidity in the solid tumors' microenvironment, which interferes with the absorption of chemotherapeutic medications. However, the exact cellular and molecular mechanisms V-ATPase plays in OSCC chemo-resistance have not been understood. Uncovering these mechanisms can contribute to combating OSCC chemo-resistance and poor prognosis. Hence, in this review, we suggest that one of these underlying mechanisms is autophagy induced by V-ATPase which can potentially contribute to OSCC chemo-resistance. Finally, specialized autophagy and V-ATPase inhibitors may be beneficial as an approach to reduce drug resistance to anticancer therapies in addition to serving as coadjuvants in antitumor treatments. Also, V-ATPase could be a prognostic factor for OSCC patients. However, in the future, more investigations are required to demonstrate these suggestions and hypotheses.