Elevated mTOR signaling increases the expression of lysosome genes, but does not alter the expression of inflammatory profiles of microglia as evaluated by low input RNAseq analysis.
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE108625 | GEO | 2018/04/17
REPOSITORIES: GEO
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Project description:Elevated mTOR signaling increases the expression of lysosome genes, but does not alter the expression of inflammatory profiles of microglia as evaluated by low input RNAseq analysis.
| PRJNA427905 | ENA
Project description:Mycobacterium tuberculosis (Mtb) infects multiple lung myeloid cell subsets and persists despite innate and adaptive immune responses. However, the mechanisms allowing Mtb to evade elimination by these subsets are not fully understood. Here, we determined that four weeks post infection, after development of adaptive immune responses, CD11clo monocyte-derived lung cells termed MNC1 (mononuclear cell subset 1), harbor more live Mtb compared to alveolar macrophages (AM), neutrophils, and less permissive CD11chi MNC2. Bulk RNA-seq analysis for these subsets identified that lysosome biogenesis pathway is underexpressed in MNC1. Functional assays confirmed that Mtb-permissive MNC1 are deficient in lysosome content, lysosomal acidification, and lysosomal activity compared to AM, and have less nuclear TFEB, a master regulator of lysosome biogenesis. Mtb infection does not alter lysosome deficiency in MNC1. Instead, Mtb recruits MNC1 and MNC2 to the lungs for its spread from AM to these subsets, which depend on Mtb ESX-1 secretion system. Furthermore, nilotinib-mediated TFEB activation enhances lysosome function of primary macrophages in vitro, and MNC1 and MNC2 in vivo, improving control of Mtb infection. Our results suggest that Mtb exploits lysosome-poor monocyte-derived lung cells for persistence; targeting lysosome biogenesis may be an effective approach to host-directed therapy for tuberculosis, enabling permissive lung cells to restrict and kill Mtb through autophagy and other mechanisms.
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Project description:Involution of the mammary gland after lactation is a dramatic example of coordinated cell death. Weaning results in the distension of the alveolar structures by the accumulation of milk, which, in turn, activates STAT3 and initiates a caspase-independent but lysosome-dependent cell death (LDCD) pathway. Although the importance of STAT3 and LDCD in early mammary involution is well established, it has not been entirely clear how milk stasis activates STAT3. In this report, we demonstrate that protein levels of the PMCA2 calcium pump are significantly downregulated within 2-4 hours of experimental milk stasis. Reductions in PMCA2 expression correlate with an increase in cytoplasmic calcium in vivo as measured by multiphoton intravital imaging of GcAMP6f fluorescence. These events occur concomitant with the appearance of nuclear pSTAT3 expression and prior to significant activation of LIF, IL6 and TGFb3 production or LDCD. Interestingly, we observed the activation of TFEB led by activation of TGFb signaling and deactivation of mTOR signaling in the involution of mammary gland. Finally, we demonstrate that increased intracellular calcium activates STAT3 by degrading SOCS3 mediated by TGFb signaling. In summary, these data suggest that intracellular calcium serves as an important biochemical signal linking milk stasis to STAT3 activation, increased lysosome biogenesis, and lysosome-mediated cell death.
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Project description:Cutaneous melanoma is characterized by lineage-specific lysosome-associated vesicular trafficking. Specifically, we report a melanoma enrichened lysophagy receptor, CCDC50, controlling lysosomal homeostasis and autolysosomal activity. We reveal that targeting CCDC50 in melanoma may be a promising therapeutic strategy, as nearly 70% of human melanomas highly express CCDC50. Moreover, targeting CCDC50 together with BRAFV600E inhibition induces synergistic function in regression of melanoma tumors, representing an alternative strategy for melanoma therapy. We performed transcriptome profiling (RNA-seq) and quantitative reverse transcription polymerase chain reaction (qRT–PCR) in shCtrl and shCCDC50 cells to evaluate the melanoma growth and metastasis controlled by CCDC50. The deep sequencing results showed that CCDC50 defciency caused increased lysosome and vacuolar memebrane and blocked autophagy flux.
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Project description:The mechanisms that govern organelle remodeling remain poorly defined. Lysosomes degrade cargo from various routes including endocytosis, phagocytosis and autophagy. For phagocytes, lysosomes are a kingpin organelle since they are essential to kill pathogens and process and present antigens. During phagocyte activation, lysosomes undergo a striking reorganization, changing from dozens of globular structures to a tubular network, in a process that requires the phosphatidylinositol-3-kinase-AKT-mTOR signalling pathway. Here, we show that lysosomes undergo a remarkable expansion in volume and holding capacity during phagocyte activation within 2 h of LPS stimulation. Lysosome expansion was paralleled by an increase in lysosomal protein levels, but this was unexpectedly independent of TFEB and TFE3 transcription factors, known to scale up lysosome biogenesis. Instead, we demonstrate a hitherto unappreciated mechanism of acute organelle expansion via mTORC1-dependent increase in translation of mRNAs encoding key lysosomal proteins. Importantly, mTORC1-dependent increase in translation activity was necessary for efficient and rapid antigen presentation by dendritic cells. Collectively, we identified a previously unknown and functionally relevant mechanism for lysosome expansion that relies on mTORC1-dependent enhanced translation of mRNAs to boost protein synthesis and lysosome biogenesis in response to an infection signal.
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Project description:Autophagy is a conserved lysosomal-dependent cellular degradation process shown to play a key role in immune defense against Mycobacterium tuberculosis inside host macrophages. Induction of autophagy enhances mycobacterial phagosome acquisition of lysosomal hydrolases, resulting in the destruction of intracellular M. tuberculosis reference strain H37Rv and strains belonging to the East African Indian genotype. However, our previous study showed that strains belonging to the hypervirulent M. tuberculosis Beijing genotype have a special ability to resist autophagic killing but the mechanism involved remains unclear. In this study, we carried out whole transcriptome analyses of host macrophages infected with the autophagy resistant Beijing strain compared to that of H37Rv. Our results identified several genes that are differentially regulated in the Beijing strain-infected host cells including those function in the lysosome positioning pathway. Host macrophages depleted of Kxd1 and Pleckhm2, two proteins in this pathway, can now enhance the lysosomal hydrolase acquisition into the Beijing phagosomes and restrict the bacterial survival upon autophagy induction. High-content image analysis showed an increase in lysosome numbers at the cell periphery in host cells infected with the autophagy resistant Beijing strain in a Pleckhm2-dependent manner. Taken together, these data indicated that the M. tuberculosis Beijing strain escapes autophagic elimination by upregulating the lysosome positioning pathway resulting in an increase in lysosome relocation toward the cell periphery and therefore sparing the mycobacteria from autophagic restriction. Our work thus identified new strategy employed by M. tuberculosis to evade autophagy which may provide potential new targets for drug discovery against tuberculosis
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Project description:Protein aggregation is a hallmark of many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). Although mutations in TARDBP, encoding TDP-43, account for less than 1% of all ALS cases, TDP-43-positive aggregates are present in nearly all ALS patients, including patients with sporadic ALS (sALS) or carrying other familial ALS (fALS)-causing mutations. Interestingly, TDP-43 inclusions are also present in subsets of patients with frontotemporal dementia, Alzheimer’s disease, and Parkinson’s disease; therefore, methods of activating intracellular protein quality control machinery capable of clearing toxic cytoplasmic TDP-43 species may alleviate disease-related phenotypes. Here, we identify a novel function of Nemo-like kinase (Nlk) as a negative regulator of lysosome biogenesis. Genetic or pharmacological reduction of Nlk increased lysosome formation and improved clearance of aggregated TDP-43. Furthermore, Nlk reduction ameliorated pathological, behavioral, and lifespan deficits in two distinct mouse models of TDP-43 proteinopathy. Because many toxic proteins can be cleared along the autophagy-lysosome axis, targeted reduction of Nlk represents a potential approach to therapy development for multiple neurodegenerative disorders.
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Project description:Defective biosynthesis of the phospholipid PI(3,5)P2 underlies neurological disorders characterized by cytoplasmic accumulation of large acidic vacuoles. To identify novel genetic causes of lysosomal vacuolization, we developed an assay for enlargement of the lysosome compartment that is amenable to cell sorting and pooled screens. After calibration on cells lacking FIG4, a known PI(3,5)P2 biosynthetic factor, we carried out a genome-wide knockout screen that captured fifteen genes, including VAC14 which is known to cause endosomal vacuolization. We selected three genes not previously associated with lysosome dysfunction for validation: C10orf35, LRRC8A, and MARCH7. We isolated two clonal knockout cell lines for each gene and confirmed loss of protein expression. The knockout lines contained enlarged acidic vesicles with surface labeling of the endolysosomal marker LAMP2. This assay will be useful for characterizing variants of unknown significance in patients with neuromuscular or lysosomal storage disorders. This genome-wide strategy for identification of genes with lysosomal function can also be adapted for drug screens to identify small molecules that correct vacuolization.
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