bims-lypmec 2022-11-06 papers

bims-lypmec

Biomed News

on Lysosomal positioning and metabolism in cardiomyocytes

Issue of 2022–11–06
seven papers selected by
Satoru Kobayashi, New York Institute of Technology

Mitochondria from the Outside in: The Relationship Between Inter-Organelle Crosstalk and Mitochondrial Internal Organization.
Spatiotemporally mapping temperature dynamics of lysosomes and mitochondria using cascade organelle-targeting upconversion nanoparticles.
Oxidative Stress Impairs Autophagy via Inhibition of Lysosomal Transport of VAMP8.
Identification of active natural products that induce lysosomal biogenesis by lysosome-based screening and biological evaluation.
Pitfalls in methods to study colocalization of nanoparticles in mouse macrophage lysosomes.
V-ATPase/TORC1-mediated ATFS-1 translation directs mitochondrial UPR activation in C. elegans.
ER-mitochondrial contact protein Miga regulates autophagy through Atg14 and Uvrag.

Contact (Thousand Oaks). 2022 Jan-Dec;5:5

Mitochondria from the Outside in: The Relationship Between Inter-Organelle Crosstalk and Mitochondrial Internal Organization.

Jonathan R Friedman.

  A fundamental role of membrane-bound organelles is the compartmentalization and organization of cellular processes. Mitochondria perform an immense number of metabolic chemical reactions and to efficiently regulate these, the organelle organizes its inner membrane into distinct morphological domains, including its characteristic cristae membranes. In recent years, a structural feature of increasing apparent importance is the inter-connection between the mitochondrial exterior and other organelles at membrane contact sites (MCSs). Mitochondria form MCSs with almost every other organelle in the cell, including the endoplasmic reticulum, lipid droplets, and lysosomes, to coordinate global cellular metabolism with mitochondrial metabolism. However, these MCSs not only facilitate the transport of metabolites between organelles, but also directly impinge on the physical shape and functional organization inside mitochondria. In this review, we highlight recent advances in our understanding of how physical connections between other organelles and mitochondria both directly and indirectly influence the internal architecture of mitochondria.

Keywords:  Ca2+; cristae; endoplasmic reticulum; inner mitochondrial membrane; interorganelle (inter-organelle); lipid droplet; lysosome; mitochondrion (mitochondria); phospholipid

DOI:  https://doi.org/10.1177/25152564221133267
Proc Natl Acad Sci U S A. 2022 Nov 08. 119(45): e2207402119

Spatiotemporally mapping temperature dynamics of lysosomes and mitochondria using cascade organelle-targeting upconversion nanoparticles.

Xiangjun Di, Dejiang Wang, Qian Peter Su, Yongtao Liu, Jiayan Liao, Mahnaz Maddahfar, Jiajia Zhou, Dayong Jin.

  The intracellular metabolism of organelles, like lysosomes and mitochondria, is highly coordinated spatiotemporally and functionally. The activities of lysosomal enzymes significantly rely on the cytoplasmic temperature, and heat is constantly released by mitochondria as the byproduct of adenosine triphosphate (ATP) generation during active metabolism. Here, we developed temperature-sensitive LysoDots and MitoDots to monitor the in situ thermal dynamics of lysosomes and mitochondria. The design is based on upconversion nanoparticles (UCNPs) with high-density surface modifications to achieve the exceptionally high sensitivity of 2.7% K-1 and low uncertainty of 0.8 K for nanothermometry to be used in living cells. We show the measurement is independent of the ion concentrations and pH values. With Ca2+ ion shock, the temperatures of both lysosomes and mitochondria increased by ∼2 to 4 °C. Intriguingly, with chloroquine (CQ) treatment, the lysosomal temperature was observed to decrease by up to ∼3 °C, while mitochondria remained relatively stable. Lastly, with oxidative phosphorylation inhibitor treatment, we observed an ∼3 to 7 °C temperature increase and a thermal transition from mitochondria to lysosomes. These observations indicate different metabolic pathways and thermal transitions between lysosomes and mitochondria inside HeLa cells. The nanothermometry probes provide a powerful tool for multimodality functional imaging of subcellular organelles and interactions with high spatial, temporal, and thermal dynamics resolutions.

Keywords:  lysosome; mitochondria; nanothermometry; upconversion nanoparticles (UCNPs)

DOI:  https://doi.org/10.1073/pnas.2207402119
Biol Pharm Bull. 2022 ;45(11): 1609-1615

Oxidative Stress Impairs Autophagy via Inhibition of Lysosomal Transport of VAMP8.

Yukiya Ohnishi, Daisuke Tsuji, Kohji Itoh.

  Autophagy is a highly conserved intracellular degrading system and its dysfunction is considered related to the cause of neurodegenerative disorders. A previous study showed that the inhibition of endocytosis transport attenuates soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein transport to lysosomes and block autophagy. The other studies demonstrated oxidative stress, one of the inducers of neurodegenerative diseases inhibits endocytosis transport. Thus, we hypothesized that oxidative stress-induced endocytosis inhibition causes alteration of SNARE protein transport to lysosomes and impairs autophagy. Here, we demonstrated that oxidative stress inhibits endocytosis and decreased the lysosomal localization of VAMP8, one of the autophagy-related SNARE proteins in a human neuroblastoma cell line. Moreover, this oxidative stress induction blocked the autophagosome-lysosome fusion step. Since we also observed decreased lysosomal localization of VAMP8 and inhibition of autophagosome-lysosome fusion in endocytosis inhibitor-treated cells, oxidative stress may inhibit VAMP8 trafficking by suppressing endocytosis and impair autophagy. Our findings suggest that oxidative stress-induced inhibition of VAMP8 trafficking to lysosomes is associated with the development of neurodegenerative diseases due to the blocked autophagosome-lysosome fusion, and may provide a new therapeutic target for restoring the autophagic activity.

Keywords:  autophagy; endocytosis; oxidative stress; soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein

DOI:  https://doi.org/10.1248/bpb.b22-00131
Heliyon. 2022 Oct;8(10): e11179

Identification of active natural products that induce lysosomal biogenesis by lysosome-based screening and biological evaluation.

Xiao Ding, Xu Yang, Yueqin Zhao, Yinyuan Wang, Jimin Fei, Zhenpeng Niu, Xianxiang Dong, Xuenan Wang, Biao Liu, Hongmei Li, Xiaojiang Hao, Yuhan Zhao.

  Lysosomal biogenesis is an essential adaptive process by which lysosomes exert their function in maintaining cellular homeostasis. Defects in lysosomal enzymes and functions lead to lysosome-related diseases, including lysosomal storage diseases and neurodegenerative disorders. Thus, activation of the autophagy-lysosomal pathway, especially induction of lysosomal biogenesis, might be an effective strategy for the treatment of lysosome-related diseases. In this study, we established a lysosome-based screening system to identify active compounds from natural products that could promote lysosomal biogenesis. The subcellular localizations of master transcriptional regulators of lysosomal genes, TFEB, TFE3 and ZKSCAN3 were examined to reveal the potential mechanisms. More than 200 compounds were screened, and we found that Hdj-23, a triterpene isolated from Walsura cochinchinensis, induced lysosomal biogenesis via activation of TFEB/TFE3. In summary, this study introduced a lysosome-based live cell screening strategy to identify bioactive compounds that promote lysosomal biogenesis, which would provide potential candidate enhancers of lysosomal biogenesis and novel insight for treating lysosome-related diseases.

Keywords:  Autophagy; Lysosomal biogenesis; Lysosome-based screening; Natural products; TFEB and TFE3

DOI:  https://doi.org/10.1016/j.heliyon.2022.e11179
J Nanobiotechnology. 2022 Oct 29. 20(1): 464

Pitfalls in methods to study colocalization of nanoparticles in mouse macrophage lysosomes.

Aura Maria Moreno-Echeverri, Eva Susnik, Dimitri Vanhecke, Patricia Taladriz-Blanco, Sandor Balog, Alke Petri-Fink, Barbara Rothen-Rutishauser.

   BACKGROUND: In the field of nanoscience there is an increasing interest to follow dynamics of nanoparticles (NP) in cells with an emphasis on endo-lysosomal pathways and long-term NP fate. During our research on this topic, we encountered several pitfalls, which can bias the experimental outcome. We address some of these pitfalls and suggest possible solutions. The accuracy of fluorescence microscopy methods has an important role in obtaining insights into NP interactions with lysosomes at the single cell level including quantification of NP uptake in a specific cell type.
METHODS: Here we use J774A.1 cells as a model for professional phagocytes. We expose them to fluorescently-labelled amorphous silica NP with different sizes and quantify the colocalization of fluorescently-labelled NP with lysosomes over time. We focus on confocal laser scanning microscopy (CLSM) to obtain 3D spatial information and follow live cell imaging to study NP colocalization with lysosomes.
RESULTS: We evaluate different experimental parameters that can bias the colocalization coefficients (i.e., Pearson's and Manders'), such as the interference of phenol red in the cell culture medium with the fluorescence intensity and image post-processing (effect of spatial resolution, optical slice thickness, pixel saturation and bit depth). Additionally, we determine the correlation coefficients for NP entering the lysosomes under four different experimental set-ups. First, we found out that not only Pearson's, but also Manders' correlation coefficient should be considered in lysosome-NP colocalization studies; second, there is a difference in NP colocalization when using NP of different sizes and fluorescence dyes and last, the correlation coefficients might change depending on live-cell and fixed-cell imaging set-up.
CONCLUSIONS: The results summarize detailed steps and recommendations for the experimental design, staining, sample preparation and imaging to improve the reproducibility of colocalization studies between the NP and lysosomes.

Keywords:  Colocalization; LysoTracker probes; Lysosomes; Macrophages; Nanoparticles; Pitfalls

DOI:  https://doi.org/10.1186/s12951-022-01670-9
J Cell Biol. 2023 Jan 02. pii: e202205045. [Epub ahead of print]222(1):

V-ATPase/TORC1-mediated ATFS-1 translation directs mitochondrial UPR activation in C. elegans.

Terytty Yang Li, Arwen W Gao, Xiaoxu Li, Hao Li, Yasmine J Liu, Amelia Lalou, Nagammal Neelagandan, Felix Naef, Kristina Schoonjans, Johan Auwerx.

To adapt mitochondrial function to the ever-changing intra- and extracellular environment, multiple mitochondrial stress response (MSR) pathways, including the mitochondrial unfolded protein response (UPRmt), have evolved. However, how the mitochondrial stress signal is sensed and relayed to UPRmt transcription factors, such as ATFS-1 in Caenorhabditis elegans, remains largely unknown. Here, we show that a panel of vacuolar H+-ATPase (v-ATPase) subunits and the target of rapamycin complex 1 (TORC1) activity are essential for the cytosolic relay of mitochondrial stress to ATFS-1 and for the induction of the UPRmt. Mechanistically, mitochondrial stress stimulates v-ATPase/Rheb-dependent TORC1 activation, subsequently promoting ATFS-1 translation. Increased translation of ATFS-1 upon mitochondrial stress furthermore relies on a set of ribosomal components but is independent of GCN-2/PEK-1 signaling. Finally, the v-ATPase and ribosomal subunits are required for mitochondrial surveillance and mitochondrial stress-induced longevity. These results reveal a v-ATPase-TORC1-ATFS-1 signaling pathway that links mitochondrial stress to the UPRmt through intimate crosstalks between multiple organelles.

DOI: https://doi.org/10.1083/jcb.202205045
Cell Rep. 2022 Nov 01. pii: S2211-1247(22)01448-6. [Epub ahead of print]41(5): 111583

ER-mitochondrial contact protein Miga regulates autophagy through Atg14 and Uvrag.

Lingna Xu, Yunyi Qiu, Xufeng Wang, Weina Shang, Jian Bai, Kexin Shi, Hao Liu, Jun-Ping Liu, Liquan Wang, Chao Tong.

  Mitochondrial malfunction and autophagy defects are often concurrent phenomena associated with neurodegeneration. We show that Miga, a mitochondrial outer-membrane protein that regulates endoplasmic reticulum-mitochondrial contact sites (ERMCSs), is required for autophagy. Loss of Miga results in an accumulation of autophagy markers and substrates, whereas PI3P and Syx17 levels are reduced. Further experiments indicated that the fusion between autophagosomes and lysosomes is defective in Miga mutants. Miga binds to Atg14 and Uvrag; concordantly, Miga overexpression results in Atg14 and Uvrag recruitment to mitochondria. The heightened PI3K activity induced by Miga requires Uvrag, whereas Miga-mediated stabilization of Syx17 is dependent on Atg14. Miga-regulated ERMCSs are critical for PI3P formation but are not essential for the stabilization of Syx17. In summary, we identify a mitochondrial protein that regulates autophagy by recruiting two alternative components of the PI3K complex present at the ERMCSs.

Keywords:  CP: Cell biology; Drosophila; ER–mitochondrial contact; autophagy; lysosome; mitochondria

DOI:  https://doi.org/10.1016/j.celrep.2022.111583