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  1. Article ; Online: Caveolin-1 promotes mitochondrial health and limits mitochondrial ROS through ROCK/AMPK regulation of basal mitophagic flux.

    Timmins, Logan R / Ortiz-Silva, Milene / Joshi, Bharat / Li, Y Lydia / Dickson, Fiona H / Wong, Timothy H / Vandevoorde, Kurt R / Nabi, Ivan R

    FASEB journal : official publication of the Federation of American Societies for Experimental Biology

    2023  Volume 38, Issue 1, Page(s) e23343

    Abstract: Caveolin-1 (CAV1), the main structural component of caveolae, is phosphorylated at tyrosine-14 (pCAV1), regulates signal transduction, mechanotransduction, and mitochondrial function, and plays contrasting roles in cancer progression. We report that ... ...

    Abstract Caveolin-1 (CAV1), the main structural component of caveolae, is phosphorylated at tyrosine-14 (pCAV1), regulates signal transduction, mechanotransduction, and mitochondrial function, and plays contrasting roles in cancer progression. We report that CRISPR/Cas9 knockout (KO) of CAV1 increases mitochondrial oxidative phosphorylation, increases mitochondrial potential, and reduces ROS in MDA-MB-231 triple-negative breast cancer cells. Supporting a role for pCAV1, these effects are reversed upon expression of CAV1 phosphomimetic CAV1 Y14D but not non-phosphorylatable CAV1 Y14F. pCAV1 is a known effector of Rho-associated kinase (ROCK) signaling and ROCK1/2 signaling mediates CAV1 promotion of increased mitochondrial potential and decreased ROS production in MDA-MB-231 cells. CAV1/ROCK control of mitochondrial potential and ROS is caveolae-independent as similar results were observed in PC3 prostate cancer cells lacking caveolae. Increased mitochondrial health and reduced ROS in CAV1 KO MDA-MB-231 cells were reversed by knockdown of the autophagy protein ATG5, mitophagy regulator PINK1 or the mitochondrial fission protein Drp1 and therefore due to mitophagy. Use of the mitoKeima mitophagy probe confirmed that CAV1 signaling through ROCK inhibited basal mitophagic flux. Activation of AMPK, a major mitochondrial homeostasis protein inhibited by ROCK, is inhibited by CAV1-ROCK signaling and mediates the increased mitochondrial potential, decreased ROS, and decreased basal mitophagy flux observed in wild-type MDA-MB-231 cells. CAV1 regulation of mitochondrial health and ROS in cancer cells therefore occurs via ROCK-dependent inhibition of AMPK. This study therefore links pCAV1 signaling activity at the plasma membrane with its regulation of mitochondrial activity and cancer cell metabolism through control of mitophagy.
    MeSH term(s) Male ; Humans ; Caveolin 1/genetics ; Caveolin 1/metabolism ; AMP-Activated Protein Kinases/genetics ; AMP-Activated Protein Kinases/metabolism ; Reactive Oxygen Species/metabolism ; Mechanotransduction, Cellular ; Mitochondria/metabolism ; Prostatic Neoplasms/genetics ; Prostatic Neoplasms/metabolism ; Mitochondrial Proteins/metabolism ; rho-Associated Kinases/genetics ; rho-Associated Kinases/metabolism
    Chemical Substances Caveolin 1 ; AMP-Activated Protein Kinases (EC 2.7.11.31) ; Reactive Oxygen Species ; Mitochondrial Proteins ; ROCK1 protein, human (EC 2.7.11.1) ; rho-Associated Kinases (EC 2.7.11.1)
    Language English
    Publishing date 2023-12-07
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 639186-2
    ISSN 1530-6860 ; 0892-6638
    ISSN (online) 1530-6860
    ISSN 0892-6638
    DOI 10.1096/fj.202201872RR
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Basal Gp78-dependent mitophagy promotes mitochondrial health and limits mitochondrial ROS

    Alan, Parsa / Vandevoorde, Kurt R. / Joshi, Bharat / Cardoen, Ben / Gao, Guang / Mohammadzadeh, Yahya / Hamarneh, Ghassan / Nabi, Ivan R.

    Cell. Mol. Life Sci.. 2022 Nov., v. 79, no. 11 p.565-565

    2022  

    Abstract: Mitochondria are major sources of cytotoxic reactive oxygen species (ROS), such as superoxide and hydrogen peroxide, that when uncontrolled contribute to cancer progression. Maintaining a finely tuned, healthy mitochondrial population is essential for ... ...

    Abstract Mitochondria are major sources of cytotoxic reactive oxygen species (ROS), such as superoxide and hydrogen peroxide, that when uncontrolled contribute to cancer progression. Maintaining a finely tuned, healthy mitochondrial population is essential for cellular homeostasis and survival. Mitophagy, the selective elimination of mitochondria by autophagy, monitors and maintains mitochondrial health and integrity, eliminating damaged ROS-producing mitochondria. However, mechanisms underlying mitophagic control of mitochondrial homeostasis under basal conditions remain poorly understood. E3 ubiquitin ligase Gp78 is an endoplasmic reticulum membrane protein that induces mitochondrial fission and mitophagy of depolarized mitochondria. Here, we report that CRISPR/Cas9 knockout of Gp78 in HT-1080 fibrosarcoma cells increased mitochondrial volume, elevated ROS production and rendered cells resistant to carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-induced mitophagy. These effects were phenocopied by knockdown of the essential autophagy protein ATG5 in wild-type HT-1080 cells. Use of the mito-Keima mitophagy probe confirmed that Gp78 promoted both basal and damage-induced mitophagy. Application of a spot detection algorithm (SPECHT) to GFP-mRFP tandem fluorescent-tagged LC3 (tfLC3)-positive autophagosomes reported elevated autophagosomal maturation in wild-type HT-1080 cells relative to Gp78 knockout cells, predominantly in proximity to mitochondria. Mitophagy inhibition by either Gp78 knockout or ATG5 knockdown reduced mitochondrial potential and increased mitochondrial ROS. Live cell analysis of tfLC3 in HT-1080 cells showed the preferential association of autophagosomes with mitochondria of reduced potential. Xenograft tumors of HT-1080 knockout cells show increased labeling for mitochondria and the cell proliferation marker Ki67 and reduced labeling for the TUNEL cell death reporter. Basal Gp78-dependent mitophagic flux is, therefore, selectively associated with reduced potential mitochondria promoting maintenance of a healthy mitochondrial population, limiting ROS production and tumor cell proliferation.
    Keywords CRISPR-Cas systems ; algorithms ; autophagosomes ; cell proliferation ; cyanides ; cytotoxicity ; endoplasmic reticulum ; fibrosarcoma ; homeostasis ; hydrazones ; hydrogen peroxide ; membrane proteins ; mitochondria ; mitophagy ; neoplasm cells ; neoplasm progression ; ubiquitin-protein ligase ; xenotransplantation
    Language English
    Dates of publication 2022-11
    Size p. 565.
    Publishing place Springer International Publishing
    Document type Article ; Online
    ZDB-ID 1358415-7
    ISSN 1420-9071 ; 1420-682X
    ISSN (online) 1420-9071
    ISSN 1420-682X
    DOI 10.1007/s00018-022-04585-8
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Basal Gp78-dependent mitophagy promotes mitochondrial health and limits mitochondrial ROS.

    Alan, Parsa / Vandevoorde, Kurt R / Joshi, Bharat / Cardoen, Ben / Gao, Guang / Mohammadzadeh, Yahya / Hamarneh, Ghassan / Nabi, Ivan R

    Cellular and molecular life sciences : CMLS

    2022  Volume 79, Issue 11, Page(s) 565

    Abstract: Mitochondria are major sources of cytotoxic reactive oxygen species (ROS), such as superoxide and hydrogen peroxide, that when uncontrolled contribute to cancer progression. Maintaining a finely tuned, healthy mitochondrial population is essential for ... ...

    Abstract Mitochondria are major sources of cytotoxic reactive oxygen species (ROS), such as superoxide and hydrogen peroxide, that when uncontrolled contribute to cancer progression. Maintaining a finely tuned, healthy mitochondrial population is essential for cellular homeostasis and survival. Mitophagy, the selective elimination of mitochondria by autophagy, monitors and maintains mitochondrial health and integrity, eliminating damaged ROS-producing mitochondria. However, mechanisms underlying mitophagic control of mitochondrial homeostasis under basal conditions remain poorly understood. E3 ubiquitin ligase Gp78 is an endoplasmic reticulum membrane protein that induces mitochondrial fission and mitophagy of depolarized mitochondria. Here, we report that CRISPR/Cas9 knockout of Gp78 in HT-1080 fibrosarcoma cells increased mitochondrial volume, elevated ROS production and rendered cells resistant to carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-induced mitophagy. These effects were phenocopied by knockdown of the essential autophagy protein ATG5 in wild-type HT-1080 cells. Use of the mito-Keima mitophagy probe confirmed that Gp78 promoted both basal and damage-induced mitophagy. Application of a spot detection algorithm (SPECHT) to GFP-mRFP tandem fluorescent-tagged LC3 (tfLC3)-positive autophagosomes reported elevated autophagosomal maturation in wild-type HT-1080 cells relative to Gp78 knockout cells, predominantly in proximity to mitochondria. Mitophagy inhibition by either Gp78 knockout or ATG5 knockdown reduced mitochondrial potential and increased mitochondrial ROS. Live cell analysis of tfLC3 in HT-1080 cells showed the preferential association of autophagosomes with mitochondria of reduced potential. Xenograft tumors of HT-1080 knockout cells show increased labeling for mitochondria and the cell proliferation marker Ki67 and reduced labeling for the TUNEL cell death reporter. Basal Gp78-dependent mitophagic flux is, therefore, selectively associated with reduced potential mitochondria promoting maintenance of a healthy mitochondrial population, limiting ROS production and tumor cell proliferation.
    MeSH term(s) Humans ; Mitophagy ; Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology ; Reactive Oxygen Species/metabolism ; Ki-67 Antigen/metabolism ; Superoxides/metabolism ; Hydrogen Peroxide/pharmacology ; Mitochondria/metabolism ; Ubiquitin-Protein Ligases/genetics ; Ubiquitin-Protein Ligases/metabolism ; Autophagy/genetics
    Chemical Substances Carbonyl Cyanide m-Chlorophenyl Hydrazone (555-60-2) ; Reactive Oxygen Species ; Ki-67 Antigen ; Superoxides (11062-77-4) ; Hydrogen Peroxide (BBX060AN9V) ; Ubiquitin-Protein Ligases (EC 2.3.2.27)
    Language English
    Publishing date 2022-10-25
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 1358415-7
    ISSN 1420-9071 ; 1420-682X
    ISSN (online) 1420-9071
    ISSN 1420-682X
    DOI 10.1007/s00018-022-04585-8
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Membrane contact site detection (MCS-DETECT) reveals dual control of rough mitochondria-ER contacts.

    Cardoen, Ben / Vandevoorde, Kurt R / Gao, Guang / Ortiz-Silva, Milene / Alan, Parsa / Liu, William / Tiliakou, Ellie / Vogl, A Wayne / Hamarneh, Ghassan / Nabi, Ivan R

    The Journal of cell biology

    2023  Volume 223, Issue 1

    Abstract: Identification and morphological analysis of mitochondria-ER contacts (MERCs) by fluorescent microscopy is limited by subpixel resolution interorganelle distances. Here, the membrane contact site (MCS) detection algorithm, MCS-DETECT, reconstructs ... ...

    Abstract Identification and morphological analysis of mitochondria-ER contacts (MERCs) by fluorescent microscopy is limited by subpixel resolution interorganelle distances. Here, the membrane contact site (MCS) detection algorithm, MCS-DETECT, reconstructs subpixel resolution MERCs from 3D super-resolution image volumes. MCS-DETECT shows that elongated ribosome-studded riboMERCs, present in HT-1080 but not COS-7 cells, are morphologically distinct from smaller smooth contacts and larger contacts induced by mitochondria-ER linker expression in COS-7 cells. RiboMERC formation is associated with increased mitochondrial potential, reduced in Gp78 knockout HT-1080 cells and induced by Gp78 ubiquitin ligase activity in COS-7 and HeLa cells. Knockdown of riboMERC tether RRBP1 eliminates riboMERCs in both wild-type and Gp78 knockout HT-1080 cells. By MCS-DETECT, Gp78-dependent riboMERCs present complex tubular shapes that intercalate between and contact multiple mitochondria. MCS-DETECT of 3D whole-cell super-resolution image volumes, therefore, identifies novel dual control of tubular riboMERCs, whose formation is dependent on RRBP1 and size modulated by Gp78 E3 ubiquitin ligase activity.
    MeSH term(s) Humans ; Endoplasmic Reticulum/metabolism ; HeLa Cells ; Mitochondria/metabolism ; Mitochondrial Membranes/metabolism ; Ubiquitin-Protein Ligases/metabolism ; Ubiquitination ; COS Cells ; Animals ; Chlorocebus aethiops ; Ribosomes/metabolism
    Chemical Substances Ubiquitin-Protein Ligases (EC 2.3.2.27)
    Language English
    Publishing date 2023-11-10
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 218154-x
    ISSN 1540-8140 ; 0021-9525
    ISSN (online) 1540-8140
    ISSN 0021-9525
    DOI 10.1083/jcb.202206109
    Database MEDical Literature Analysis and Retrieval System OnLINE

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