Project description:Emerging evidences suggest that both function and position of organelles are pivotal for tumor cell dissemination. Among them, lysosomes stand out as they integrate metabolic sensing with gene regulation and secretion of proteases. Yet, how lysosomes function is linked to their position and thereby control metastatic progression remains elusive. Here, we analyzed lysosome subcellular distribution in micropatterned patient-derived melanoma cells and found that lysosome spreading scales with their aggressiveness. Peripheral lysosomes promote invadopodia-based matrix degradation and invasion of melanoma cells which is directly linked to their lysosomal and cell transcriptional programs. When controlling lysosomal positioning using chemo-genetical heterodimerization in melanoma cells, we demonstrated that perinuclear clustering impairs lysosomal secretion, matrix degradation and invasion. Impairing lysosomal spreading in a zebrafish metastasis model significantly reduces invasive outgrowth. Our study provides a mechanistic demonstration that lysosomal positioning controls cell invasion, illustrating the importance of organelle adaptation in carcinogenesis.
Project description:The whole-cell scale spatial organization of lysosomes is regulated by their bidirectional motility on microtubule tracks. Small GTP-binding (G) protein, Arl8b, stimulates the anterograde transport of lysosomes by recruiting adaptor protein SKIP (also known as PLEKHM2), which in turn couples the microtubule motor kinesin-1. Here, we have identified an Arl8b effector, RUN and FYVE domaincontaining protein family member 3, RUFY3, which drives the retrograde transport of lysosomes. Artificial targeting of RUFY3 to the surface of mitochondria was sufficient to drive their perinuclear positioning. We find that RUFY3 interacts with the JIP4-Dynein-Dynactin complex and mediates Arl8b association with the retrograde motor complex. The mobile fraction of the total lysosomes per cell was significantly enhanced upon RUFY3 depletion, suggesting that RUFY3 maintains the lysosomes clustering within the perinuclear cloud. Expectedly, RUFY3 knockdown disrupted the perinuclear positioning of lysosomes upon nutrient starvation and/or serum depletion, although lysosome continued to undergo fusion with autophagosomes. Interestingly, lysosome fission events were more frequent in RUFY3-depleted cells and accordingly, there was a striking reduction in lysosome size, an effect that was also observed
Project description:Purpose. Aggressiveness is a crucial issue related to cutaneous melanoma malignancy and its high metastatic potential. Aim of this work is to identify new pathways or molecules controlling melanoma cell aggressiveness. Proliferation, migration and invasion capability under serum stimulation were analyzed in 12 human metastatic melanoma cell lines to identify the most aggressive ones as a model. The most proliferating/invading (defines as the most aggressive) A375 cell line was compared to the less aggressive one, Sk mel 28 by means of different approaches: 1) transcriptomic analysis by ILLUMINA platform; 2) proteomic study through LC-MS/MS analysis; 3) multiplexed assay to measure secretion of cytokines in conditioned media bioinformatic analysis was then carried out. Two groups of cells significantly differing in aggressiveness were identified and 2 cell lines, namely A375 and SK-Mel-28 were selected as model of the most and the less aggressive phenotype, respectively. A multi-omic analysis of several experimental datasets derived from transcriptomic, proteomic (mass spectrometric) and cytokinomic data was then carried out via Ingenuity Pathway Analysis (IPA) software. Analysis of upstream regulators and network analysis, indicated that the expression of tumor necrosis factor (TNF) were significantly differently expressed and functioning. The involvement of these pathways was confirmed by functional validation studies as zymography and proliferation studies and the most significantly upregulated pathway (TNF-alfa) was tested. Five melanoma cell lines with different MAGS were treated with an anti-TNFα monoclonal antibody and the most aggressive ones were highly significantly affected.
Project description:Lysosomes are central platforms for not only the degradation of macromolecules but also the integration of multiple signaling pathways. However, whether and how lysosomes mediate the mitochondrial stress response (MSR) remain largely unknown. Here, we demonstrate that lysosomal acidification via the vacuolar H+-ATPase (v-ATPase) is essential for the transcriptional activation of the mitochondrial unfolded protein response (UPRmt). Mitochondrial stress stimulates v-ATPase-mediated lysosomal activation of the mechanistic target of rapamycin complex 1 (mTORC1), which then directly phosphorylates the MSR transcription factor, activating transcription factor 4 (ATF4). Disruption of mTORC1-dependent ATF4 phosphorylation blocks the UPRmt, but not other similar stress responses, such as the UPRER. Finally, ATF4 phosphorylation downstream of the v-ATPase/mTORC1 signaling is indispensable for sustaining mitochondrial redox homeostasis and protecting cells from reactive oxygen species (ROS)-associated cell death upon mitochondrial stress. Thus, v-ATPase/mTORC1-mediated ATF4 phosphorylation via lysosomes links mitochondrial stress to UPRmt activation and mitochondrial function resilience.
Project description:This SuperSeries is composed of the following subset Series: GSE41971: In vivo NCL-targeting affects breast cancer aggressiveness through miRNA regulation [NanoString] GSE41972: In vivo NCL-targeting affects breast cancer aggressiveness through miRNA regulation [Affymetrix] Refer to individual Series
Project description:Faithful execution of developmental programs relies on the acquisition of unique cell identities from pluripotent progenitors, a process governed by combinatorial inputs from numerous signaling cascades that ultimately dictate lineage-specific transcriptional outputs. Despite growing evidence that metabolism is integrated with many molecular networks, how pathways that control energy homeostasis may affect cell fate decisions is largely unknown. Here, we show that AMPK, a central metabolic regulator, plays critical roles in lineage specification. Although AMPK-deficient embryonic stem cells (ESCs) were normal in the pluripotent state, these cells displayed profound defects upon differentiation, failing to generate chimeric embryos and preferentially adopting an ectodermal fate at the expense of the endoderm during embryoid body (EB) formation. AMPK-/- EBs exhibited reduced levels of Tfeb, a master transcriptional regulator of lysosomes, leading to diminished endolysosomal function. Remarkably, genetic loss of Tfeb also yielded endodermal defects, while AMPK-null ESCs over-expressing this transcription factor normalized their differential potential, revealing an intimate connection between Tfeb/lysosomes and germ layer specification. The compromised endolysosomal system resulting from AMPK or Tfeb inactivation blunted Wnt signaling, while up-regulating this pathway restored expression of endodermal markers. Collectively, these results uncover the AMPK pathway as a novel regulator of cell fate determination during differentiation. 2 WT and 2 AMPK DKO ESC lines were differentiated into embryoid bodies (EBs) for various lengths of time (2, 4, 8, and 12 days) in high and low glucose conditions. Both ESC and EB samples were profiled by mRNA-seq to examine how global gene expression changes associated with ESC differentiation are affected by AMPK deletion.
Project description:Genetic variation at the leucine-rich repeat kinase 2 (LRRK2) locus contributes to an enhanced risk of familial and sporadic Parkinson's disease. Previous data have demonstrated that recruitment to various membranes of the endolysosomal system results in LRRK2 activation. However, the mechanism(s) underlying LRRK2 activation at endolysosomal membranes and the cellular consequences of these events are still poorly understood. Here, we directed LRRK2 to lysosomes and early endosomes, triggering both LRRK2 autophosphorylation and phosphorylation of the direct LRRK2 substrates Rab10 and Rab12. However, when directed to the lysosomal membrane, pRab10 was restricted to perinuclear lysosomes, whereas pRab12 was visualized on both peripheral and perinuclear LRRK2+ lysosomes, suggesting that lysosomal positioning provides additional regulation of LRRK2-dependent Rab phosphorylation. Anterograde transport of lysosomes to the cell periphery by increasing the expression of ARL8B and SKIP or by knockdown of JIP4 blocked the recruitment and phosphorylation of Rab10 by LRRK2. The absence of pRab10 from the lysosomal membrane prevented the formation of a lysosomal tubulation and sorting process we previously named LYTL. Conversely, overexpression of RILP resulted in lysosomal clustering within the perinuclear area and increased LRRK2-dependent Rab10 recruitment and phosphorylation. The regulation of Rab10 phosphorylation in the perinuclear area depends on counteracting phosphatases, as the knockdown of phosphatase PPM1H significantly increased pRab10 signal and lysosomal tubulation in the perinuclear region. Our findings suggest that LRRK2 can be activated at multiple cellular membranes, including lysosomes, and that lysosomal positioning further provides the regulation of some Rab substrates likely via differential phosphatase activity or effector protein presence in nearby cellular compartments.
Project description:We show that lysosomes are antagonistically controlled by TFEB and MYC to balance catabolic and anabolic processes required for activating LT-HSC and guiding their lineage fate. TFEB-mediated induction of the endolysosomal pathway for membrane receptor degradation limits LT-HSC metabolic and mitogenic activation; this promotes quiescence and self-renewal and governs erythroid-myeloid commitment. By contrast, MYC engages biosynthetic processes while repressing lysosomal catabolism to drive LT-HSC activation. Collectively, our study identifies lysosomes as a central regulatory hub for proper and coordinated stem cell fate determination.