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Loss of functional MYO1C/myosin 1c, a motor protein involved in lipid raft trafficking, disrupts autophagosome-lysosome fusion

Loss of functional MYO1C/myosin 1c, a motor protein involved in lipid raft trafficking, disrupts autophagosome-lysosome fusion
Loss of functional MYO1C/myosin 1c, a motor protein involved in lipid raft trafficking, disrupts autophagosome-lysosome fusion
MYO1C, a single-headed class I myosin, associates with cholesterol-enriched lipid rafts and facilitates their recycling from intracellular compartments to the cell surface. Absence of functional MYO1C disturbs the cellular distribution of lipid rafts, causes the accumulation of cholesterol-enriched membranes in the perinuclear recycling compartment, and leads to enlargement of endolysosomal membranes. Several feeder pathways, including classical endocytosis but also the autophagy pathway, maintain the health of the cell by selective degradation of cargo through fusion with the lysosome. Here we show that loss of functional MYO1C leads to an increase in total cellular cholesterol and its disrupted subcellular distribution. We observe an accumulation of autophagic structures caused by a block in fusion with the lysosome and a defect in autophagic cargo degradation. Interestingly, the loss of MYO1C has no effect on degradation of endocytic cargo such as EGFR, illustrating that although the endolysosomal compartment is enlarged in size, it is functional, contains active hydrolases, and the correct pH. Our results highlight the importance of correct lipid composition in autophagosomes and lysosomes to enable them to fuse. Ablating MYO1C function causes abnormal cholesterol distribution, which has a major selective impact on the autophagy pathway.
autophagy, cholesterol, electron microscopy, lipid raft, lysosome, MYO1C, BafA1, bafilomycin A1, EM, EGF, epidermal growth factor, EGFR, epidermal growth factor receptor, GFP, green fluorescent protein, KD, knockdown, LAMP1, lysosomal-associated membrane protein 1, LC3, microtubule-associated protein 1 light chain 3, myosin IC, MVB, multivesicular body, PB, phosphate buffer, PCIP, pentachloropseudilin, PtdIns(4, 5)P2, phosphatidylinositol 4, 5-bisphosphate, RFP, red fluorescent protein, RPE, retinal pigment epithelium
1554-8627
2310-2323
Brandstaetter, Hemma
a689590c-21be-4d1f-8e84-280c4509aca5
Kishi-Itakura, Chieko
f337baa1-f9e5-4d78-bac1-f89fb6f6382a
Tumbarello, David A
75c6932e-fdbf-4d3c-bb4f-48fbbdba93a2
Manstein, Dietmar J.
018cf8c2-7e3d-48b4-9a25-c24a8cef3160
Buss, Folma
f8b3fde3-6724-4412-aa65-674cbfb73121
Brandstaetter, Hemma
a689590c-21be-4d1f-8e84-280c4509aca5
Kishi-Itakura, Chieko
f337baa1-f9e5-4d78-bac1-f89fb6f6382a
Tumbarello, David A
75c6932e-fdbf-4d3c-bb4f-48fbbdba93a2
Manstein, Dietmar J.
018cf8c2-7e3d-48b4-9a25-c24a8cef3160
Buss, Folma
f8b3fde3-6724-4412-aa65-674cbfb73121

Brandstaetter, Hemma, Kishi-Itakura, Chieko, Tumbarello, David A, Manstein, Dietmar J. and Buss, Folma (2015) Loss of functional MYO1C/myosin 1c, a motor protein involved in lipid raft trafficking, disrupts autophagosome-lysosome fusion. Autophagy, 10 (12), 2310-2323. (doi:10.4161/15548627.2014.984272). (PMID:25551774)

Record type: Article

Abstract

MYO1C, a single-headed class I myosin, associates with cholesterol-enriched lipid rafts and facilitates their recycling from intracellular compartments to the cell surface. Absence of functional MYO1C disturbs the cellular distribution of lipid rafts, causes the accumulation of cholesterol-enriched membranes in the perinuclear recycling compartment, and leads to enlargement of endolysosomal membranes. Several feeder pathways, including classical endocytosis but also the autophagy pathway, maintain the health of the cell by selective degradation of cargo through fusion with the lysosome. Here we show that loss of functional MYO1C leads to an increase in total cellular cholesterol and its disrupted subcellular distribution. We observe an accumulation of autophagic structures caused by a block in fusion with the lysosome and a defect in autophagic cargo degradation. Interestingly, the loss of MYO1C has no effect on degradation of endocytic cargo such as EGFR, illustrating that although the endolysosomal compartment is enlarged in size, it is functional, contains active hydrolases, and the correct pH. Our results highlight the importance of correct lipid composition in autophagosomes and lysosomes to enable them to fuse. Ablating MYO1C function causes abnormal cholesterol distribution, which has a major selective impact on the autophagy pathway.

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Accepted/In Press date: 22 July 2014
e-pub ahead of print date: 31 December 2014
Published date: 28 January 2015
Additional Information: Brandstaetter, Kishi-Itakura, and Tumbarello contributed equally to this article
Keywords: autophagy, cholesterol, electron microscopy, lipid raft, lysosome, MYO1C, BafA1, bafilomycin A1, EM, EGF, epidermal growth factor, EGFR, epidermal growth factor receptor, GFP, green fluorescent protein, KD, knockdown, LAMP1, lysosomal-associated membrane protein 1, LC3, microtubule-associated protein 1 light chain 3, myosin IC, MVB, multivesicular body, PB, phosphate buffer, PCIP, pentachloropseudilin, PtdIns(4, 5)P2, phosphatidylinositol 4, 5-bisphosphate, RFP, red fluorescent protein, RPE, retinal pigment epithelium
Organisations: Centre for Biological Sciences

Identifiers

Local EPrints ID: 373994
URI: https://eprints.soton.ac.uk/id/eprint/373994
ISSN: 1554-8627
PURE UUID: 3580988b-2314-43e7-86b9-fdebb5167cba
ORCID for David A Tumbarello: ORCID iD orcid.org/0000-0002-5169-0561

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Date deposited: 03 Feb 2015 12:39
Last modified: 16 Jul 2019 00:37

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