bims-lypmec 2022-11-27 papers

bims-lypmec

Biomed News

on Lysosomal positioning and metabolism in cardiomyocytes

Issue of 2022‒11‒27
eight papers selected by
Satoru Kobayashi
New York Institute of Technology

Quantitative 3D correlative light and electron microscopy of organelle association during autophagy.
Overlapping Machinery in Lysosome-Related Organelle Trafficking: A Lesson from Rare Multisystem Disorders.
Cholesterol transfer via endoplasmic reticulum contacts mediates lysosome damage repair.
Autophagic lysosome reformation in health and disease.
Intracellular cholesterol transport inhibition Impairs autophagy flux by decreasing autophagosome-lysosome fusion.
Bioimaging of Lysosomes with a BODIPY pH-Dependent Fluorescent Probe.
AP2S1 regulates APP degradation through late endosome-lysosome fusion in cells and APP/PS1 mice.
Editorial: "Molecular mechanisms and physiological significance of organelle interactions and cooperation-Volume II".

Cell Struct Funct. 2022 Nov 22.

Quantitative 3D correlative light and electron microscopy of organelle association during autophagy.

Satoru Takahashi, Chieko Saito, Ikuko Koyama-Honda, Noboru Mizushima.

  In macroautophagy, disk-shaped double-membrane structures called phagophores elongate to form cup-shaped structures, becoming autophagosomes upon closure. These autophagosomes then fuse with lysosomes to become autolysosomes and degrade engulfed material. Autophagosome formation is reported to involve other organelles, including the endoplasmic reticulum (ER) and mitochondria. Organelles are also taken up by autophagosomes as autophagy cargos. However, few studies have performed systematic spatiotemporal analysis of inter-organelle relationships during macroautophagy. Here, we investigated the organelles in contact with phagophores, autophagosomes, and autolysosomes by using three-dimensional correlative light and electron microscopy with array tomography in cells starved 30 min. As previously reported, all phagophores associate with the ER. The surface area of phagophores in contact with the ER decreases gradually as they mature into autophagosomes and autolysosomes. However, the ER still associates with 92% of autophagosomes and 79% of autolysosomes, suggesting that most autophagosomes remain on the ER after closure and even when they fuse with lysosomes. In addition, we found that phagophores form frequently near other autophagic structures, suggesting the presence of potential hot spots for autophagosome formation. We also analyzed the contents of phagophores and autophagosomes and found that the ER is the most frequently engulfed organelle (detected in 65% of total phagophores and autophagosomes). These quantitative three-dimensional ultrastructural data provide insights into autophagosome-organelle relationships during macroautophagy. Key words: 3D-CLEM, autophagosome, electron microscopy, endoplasmic reticulum, lysosome.

Keywords:  3D-CLEM; autophagosome; electron microscopy; endoplasmic reticulum; lysosome

DOI:  https://doi.org/10.1247/csf.22071
Cells. 2022 Nov 21. pii: 3702. [Epub ahead of print]11(22):

Overlapping Machinery in Lysosome-Related Organelle Trafficking: A Lesson from Rare Multisystem Disorders.

Blerida Banushi, Fiona Simpson.

  Lysosome-related organelles (LROs) are a group of functionally diverse, cell type-specific compartments. LROs include melanosomes, alpha and dense granules, lytic granules, lamellar bodies and other compartments with distinct morphologies and functions allowing specialised and unique functions of their host cells. The formation, maturation and secretion of specific LROs are compromised in a number of hereditary rare multisystem disorders, including Hermansky-Pudlak syndromes, Griscelli syndrome and the Arthrogryposis, Renal dysfunction and Cholestasis syndrome. Each of these disorders impacts the function of several LROs, resulting in a variety of clinical features affecting systems such as immunity, neurophysiology and pigmentation. This has demonstrated the close relationship between LROs and led to the identification of conserved components required for LRO biogenesis and function. Here, we discuss aspects of this conserved machinery among LROs in relation to the heritable multisystem disorders they associate with, and present our current understanding of how dysfunctions in the proteins affected in the disease impact the formation, motility and ultimate secretion of LROs. Moreover, we have analysed the expression of the members of the CHEVI complex affected in Arthrogryposis, Renal dysfunction and Cholestasis syndrome, in different cell types, by collecting single cell RNA expression data from the human protein atlas. We propose a hypothesis describing how transcriptional regulation could constitute a mechanism that regulates the pleiotropic functions of proteins and their interacting partners in different LROs.

Keywords:  Arthrogryposis-Renal dysfunction-Cholestasis; Griscelli syndrome; Hermansky–Pudlak Syndrome; VIPAR; VPS33B; cargo-sorting; endosomes; lysosome-related organelles; membrane trafficking; multisystem disorders

DOI:  https://doi.org/10.3390/cells11223702
EMBO J. 2022 Nov 21. e112677

Cholesterol transfer via endoplasmic reticulum contacts mediates lysosome damage repair.

Maja Radulovic, Eva Maria Wenzel, Sania Gilani, Lya Kk Holland, Alf Håkon Lystad, Santosh Phuyal, Vesa M Olkkonen, Andreas Brech, Marja Jäättelä, Kenji Maeda, Camilla Raiborg, Harald Stenmark.

  Lysosome integrity is essential for cell viability, and lesions in lysosome membranes are repaired by the ESCRT machinery. Here, we describe an additional mechanism for lysosome repair that is activated independently of ESCRT recruitment. Lipidomic analyses showed increases in lysosomal phosphatidylserine and cholesterol after damage. Electron microscopy demonstrated that lysosomal membrane damage is rapidly followed by the formation of contacts with the endoplasmic reticulum (ER), which depends on the ER proteins VAPA/B. The cholesterol-binding protein ORP1L was recruited to damaged lysosomes, accompanied by cholesterol accumulation by a mechanism that required VAP-ORP1L interactions. The PtdIns 4-kinase PI4K2A rapidly produced PtdIns4P on lysosomes upon damage, and knockout of PI4K2A inhibited damage-induced accumulation of ORP1L and cholesterol and led to the failure of lysosomal membrane repair. The cholesterol-PtdIns4P transporter OSBP was also recruited upon damage, and its depletion caused lysosomal accumulation of PtdIns4P and resulted in cell death. We conclude that ER contacts are activated on damaged lysosomes in parallel to ESCRTs to provide lipids for membrane repair, and that PtdIns4P generation and removal are central in this response.

Keywords:  cholesterol; lysosome; membrane contact site; membrane repair; phosphoinositide

DOI:  https://doi.org/10.15252/embj.2022112677
Autophagy. 2022 Nov 21. 1-18

Autophagic lysosome reformation in health and disease.

Randini Nanayakkara, Rajendra Gurung, Samuel J Rodgers, Matthew J Eramo, Georg Ramm, Christina A Mitchell, Meagan J McGrath.

  Lysosomes are the primary degradative compartment within cells and there have been significant advances over the past decade toward understanding how lysosome homeostasis is maintained. Lysosome repopulation ensures sustained autophagy function, a fundamental process that protects against disease. During macroautophagy/autophagy, cellular debris is sequestered into phagophores that mature into autophagosomes, which then fuse with lysosomes to generate autolysosomes in which contents are degraded. Autophagy cannot proceed without the sufficient generation of lysosomes, and this can be achieved via their de novo biogenesis. Alternatively, during autophagic lysosome reformation (ALR), lysosomes are generated via the recycling of autolysosome membranes. During this process, autolysosomes undergo significant membrane remodeling and scission to generate membrane fragments, that mature into functional lysosomes. By utilizing membranes already formed during autophagy, this facilitates an efficient pathway for re-deriving lysosomes, particularly under conditions of prolonged autophagic flux. ALR dysfunction is emerging as an important disease mechanism including for neurodegenerative disorders such as hereditary spastic paraplegia and Parkinson disease, neuropathies including Charcot-Marie-Tooth disease, lysosome storage disorders, muscular dystrophy, metabolic syndrome, and inflammatory and liver disorders. Here, we provide a comprehensive review of ALR, including an overview of its dynamic spatiotemporal regulation by MTOR and phosphoinositides, and the role ALR dysfunction plays in many diseases.

Keywords:  Autophagic lysosome reformation; MTOR; PtdIns(4,5)P2; PtdIns4P; lysosome; phosphoinositide

DOI:  https://doi.org/10.1080/15548627.2022.2128019
Cell Commun Signal. 2022 Nov 25. 20(1): 189

Intracellular cholesterol transport inhibition Impairs autophagy flux by decreasing autophagosome-lysosome fusion.

Yunash Maharjan, Raghbendra Kumar Dutta, Jinbae Son, Xiaofan Wei, Channy Park, Hyug Moo Kwon, Raekil Park.

  BACKGROUND: Autophagy is an intracellular degradation process crucial for homeostasis. During autophagy, a double-membrane autophagosome fuses with lysosome through SNARE machinery STX17 to form autolysosome for degradation of damaged organelle. Whereas defective autophagy enhances cholesterol accumulation in the lysosome and impaired autophagic flux that results Niemann-Pick type C1 (NPC1) disease. However, exact interconnection between NPC1 and autophagic flux remain obscure due to the existence of controversial reports.RESULTS: This study aimed at a comparison of the effects of three autophagic inhibitor drugs, including chloroquine, U18666A, and bafilomycin A1, on the intracellular cholesterol transport and autophagy flux. Chloroquine, an autophagic flux inhibitor; U1866A, a NPC1 inhibitor, and bafilomycin A, a lysosomotropic agent are well known to inhibit autophagy by different mechanism. Here we showed that treatment with U1866A and bafilomycin A induces lysosomal cholesterol accumulation that prevented autophagic flux by decreasing autophagosome-lysosome fusion. We also demonstrated that accumulation of cholesterol within the lysosome did not affect lysosomal pH. Although the clearance of accumulated cholesterol by cyclodextrin restored the defective autophagosome-lysosome fusion, the autophagy flux restoration was possible only when lysosomal acidification was not altered. In addition, a failure of STX17 trafficking to autophagosomes plays a key role in prevention of autophagy flux caused by intracellular cholesterol transport inhibitors.
CONCLUSIONS: Our data provide a new insight that the impaired autophagy flux does not necessarily result in lysosomal cholesterol accumulation even though it prevents autophagosome-lysosome fusion. Video abstract.

Keywords:  Autophagosomes; Autophagy flux; Bafilomycin A1; Chloroquine; Intracellular cholesterol transport; STX17; U18666A

DOI:  https://doi.org/10.1186/s12964-022-00942-z
Molecules. 2022 Nov 20. pii: 8065. [Epub ahead of print]27(22):

Bioimaging of Lysosomes with a BODIPY pH-Dependent Fluorescent Probe.

Raquel C R Gonçalves, Efres Belmonte-Reche, João Pina, Milene Costa da Silva, Sónia C S Pinto, Juan Gallo, Susana P G Costa, M Manuela M Raposo.

  Fluorescence-based probes represent a powerful tool for noninvasive imaging of living systems in real time and with a high temporal and spatial resolution. Amongst several known fluorophores, 3-difluoroborodipyrromethene (BODIPY) derivatives have become a cornerstone for innovative fluorescent labelling applications, mainly due to their advantageous features including their facile synthesis, structural versatility and exceptional photophysical properties. In this context, we report a BODIPY-based fluorescent probe for imaging of lysosomes in living cells. The BODIPY derivative displayed a remarkable fluorescence enhancement at low pH values with a pKa* of 3.1. In vitro studies by confocal microscopy in HeLa cells demonstrated that the compound was able to permeate cell membrane and selectively label lysosome whilst remaining innocuous to the cell culture at the maximum concentration tested. Herein, the BODIPY derivative holds the promise of investigating lysosomal dynamics and function in living cells through fluorescence imaging.

Keywords:  BODIPY; bioimaging; fluorescent probe; lysosomes; pH; synthesis

DOI:  https://doi.org/10.3390/molecules27228065
Traffic. 2022 Nov 22.

AP2S1 regulates APP degradation through late endosome-lysosome fusion in cells and APP/PS1 mice.

Qi-Xin Wen, Biao-Luo, Xiao-Yong Xie, Gui-Feng Zhou, Jian Chen, Li Song, Shi-Qi Xie, Long Chen, Kun-Yi Li, Xiao-Jiao Xiang, Guo-Jun Chen.

  AP2S1 is the sigma 2 subunit of adaptor protein 2 (AP2) that is essential for endocytosis. In this study, we investigated the potential role of AP2S1 in intracellular processing of amyloid precursor protein (APP), which contributes to the pathogenesis of Alzheimer's disease (AD) by generating the toxic β-amyloid peptide (Aβ). We found that knockdown or overexpression of AP2S1 decreased or increased the protein levels of APP and Aβ in cells stably expressing human full-length APP695, respectively. This effect was unrelated to endocytosis but involved lysosomal degradation. Morphological studies revealed that silencing of AP2S1 promoted the translocalization of APP from RAB9-positive late endosomes (LE) to LAMP1-positive lysosomes, which was paralleled by the enhanced LE-lysosome fusion. In support, silencing of vacuolar protein sorting-associated protein 41 (VPS41) that is implicated in LE-lyso fusion prevented AP2S1-mediated regulation of APP degradation and translocalization. In APP/PS1 mice, an animal model of AD, AAV-mediated delivery of AP2S1 shRNA in the hippocampus significantly reduced the protein levels of APP and Aβ, with the concomitant APP translocalization, LE-lyso fusion and the improved cognitive functions. Taken together, these data uncover a LE-lyso fusion mechanism in APP degradation and suggest a novel role for AP2S1 in the pathophysiology of AD.

Keywords:  APP; Adapter protein 2; Alzheimer's disease; Aβ; Endosome-lysosome fusion; Sigma subunit

DOI:  https://doi.org/10.1111/tra.12874
Front Cell Dev Biol. 2022 ;10 1076670

Editorial: "Molecular mechanisms and physiological significance of organelle interactions and cooperation-Volume II".

Joseph Costello, Markus Islinger, Michael Schrader.



Keywords:  lipid droplets; membrane contact sites; mitochondria; organelle interaction; organelles; peroxisomes

DOI:  https://doi.org/10.3389/fcell.2022.1076670