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244 results on '"Melia, Thomas J."'

10. Fusion of Cells by Flipped SNAREs

Author

Hu, Chuan, Ahmed, Mahiuddin, Melia, Thomas J., Söllner, Thomas H., Mayer, Thomas, and Rothman, James E.

Published
2003

12. Spartin-mediated lipid transfer facilitates lipid droplet turnover.

Author

Neng Wan, Zhouping Hong, Parson, Matthew A. H., Korfhage, Justin L., Burke, John E., Melia, Thomas J., and Reinisch, Karin M.

Subjects
LIPID transfer protein, MEMBRANE lipids, LIPIDS, THRESHOLD energy
Abstract

Lipid droplets (LDs) are organelles critical for energy storage and membrane lipid homeostasis, whose number and size are carefully regulated in response to cellular conditions. The molecular mechanisms underlying lipid droplet biogenesis and degradation, however, are not well understood. The Troyer syndrome protein spartin (SPG20) supports LD delivery to autophagosomes for turnover via lipophagy. Here, we characterize spartin as a lipid transfer protein whose transfer ability is required for LD degradation. Spartin copurifies with phospholipids and neutral lipids from cells and transfers phospholipids in vitro via its senescence domain. A senescence domain truncation that impairs lipid transfer in vitro also impairs LD turnover in cells while not affecting spartin association with either LDs or autophagosomes, supporting that spartin's lipid transfer ability is physiologically relevant. Our data indicate a role for spartin-mediated lipid transfer in LD turnover. [ABSTRACT FROM AUTHOR]

Published
2024
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30. Selective Activation of Cognate SNAREpins by Sec1/Munc18 Proteins

Author

Shen, Jingshi, Tareste, David C., Paumet, Fabienne, Rothman, James E., and Melia, Thomas J.

Subjects
Proteins -- Physiological aspects, Biological sciences
Abstract

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2006.12.016 Byline: Jingshi Shen (1), David C. Tareste (1), Fabienne Paumet (1), James E. Rothman (1), Thomas J. Melia (1) Abstract: Sec1/Munc18 (SM) proteins are required for every step of intracellular membrane fusion, but their molecular mechanism of action has been unclear. In this work, we demonstrate a fundamental role of the SM protein: to act as a stimulatory subunit of its cognate SNARE fusion machinery. In a reconstituted system, mammalian SNARE pairs assemble between bilayers to drive a basal fusion reaction. Munc18-1/nSec1, a synaptic SM protein required for neurotransmitter release, strongly accelerates this reaction through direct contact with both t- and v-SNAREs. Munc18-1 accelerates fusion only for the cognate SNAREs for exocytosis, therefore enhancing fusion specificity. Author Affiliation: (1) Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA Article History: Received 23 July 2006; Revised 31 October 2006; Accepted 5 December 2006 Article Note: (miscellaneous) Published: January 11, 2007

Published
2007

35. The insufficiency of ATG4A in macroautophagy

Author

Nguyen, Nathan, primary, Olivas, Taryn J., additional, Mires, Antonio, additional, Jin, Jiaxin, additional, Yu, Shenliang, additional, Luan, Lin, additional, Nag, Shanta, additional, Kauffman, Karlina J., additional, and Melia, Thomas J., additional

Published
2020
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38. Closing the autophagosome is easy‐PC.

Author

Fuller, Devin M and Melia, Thomas J

Subjects
*MEMBRANE lipids, *LECITHIN, *AUTOPHAGY
Abstract

In their recent article, Polyansky et al identify phosphatidylcholine (PC) as the most abundant lipid in the autophagosome membrane and demonstrate that eliminating de novo PC synthesis sharply impairs autophagic processing. In the absence of PC synthesis, open cup‐like structures accumulate, implicating PC as a key component in the closure of autophagosomes. [ABSTRACT FROM AUTHOR]

Published
2023
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40. Distinct functions of ATG16L1 isoforms in membrane binding and LC3B lipidation in autophagy-related processes

Author

Lystad, Aif Hakon, Carlsson, Sven R, de la Ballina, Laura R., Kauffman, Karlina J., Nag, Shanta, Yoshimori, Tamotsu, Melia, Thomas J., Simonsen, Anne, Lystad, Aif Hakon, Carlsson, Sven R, de la Ballina, Laura R., Kauffman, Karlina J., Nag, Shanta, Yoshimori, Tamotsu, Melia, Thomas J., and Simonsen, Anne

Abstract

Covalent modification of LC3 and GABARAP proteins to phosphatidylethanolamine in the double-membrane phagophore is a key event in the early phase of macroautophagy, but can also occur on single-membrane structures. In both cases this involves transfer of LC3/GABARAP from ATG3 to phosphatidylethanolamine at the target membrane. Here we have purified the full-length human ATG12-5-ATG16L1 complex and show its essential role in LC3B/GABARAP lipidation in vitro. We have identified two functionally distinct membrane-binding regions in ATG16L1. An N-terminal membrane-binding amphipathic helix is required for LC3B lipidation under all conditions tested. By contrast, the C-terminal membrane-binding region is dispensable for canonical autophagy but essential for VPS34-independent LC3B lipidation at perturbed endosomes. We further show that the ATG16L1 C-terminus can compensate for WIPI2 depletion to sustain lipidation during starvation. This C-terminal membrane-binding region is present only in the beta-isoform of ATG16L1, showing that ATG16L1 isoforms mechanistically distinguish between different LC3B lipidation mechanisms under different cellular conditions.

Published
2019
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46. A Programmable DNA Origami Platform for Organizing Intrinsically Disordered Nucleoporins within Nanopore Confinement

Author

Fisher, Patrick D. Ellis, primary, Shen, Qi, additional, Akpinar, Bernice, additional, Davis, Luke K., additional, Chung, Kenny Kwok Hin, additional, Baddeley, David, additional, Šarić, Anđela, additional, Melia, Thomas J., additional, Hoogenboom, Bart W., additional, Lin, Chenxiang, additional, and Lusk, C. Patrick, additional

Published
2018
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49. HS1BP3 negatively regulates autophagy by modulation of phosphatidic acid levels

Author

Holland, Petter, primary, Knævelsrud, Helene, additional, Søreng, Kristiane, additional, Mathai, Benan J., additional, Lystad, Alf Håkon, additional, Pankiv, Serhiy, additional, Bjørndal, Gunnveig T., additional, Schultz, Sebastian W., additional, Lobert, Viola H., additional, Chan, Robin B., additional, Zhou, Bowen, additional, Liestøl, Knut, additional, Carlsson, Sven R., additional, Melia, Thomas J., additional, Di Paolo, Gilbert, additional, and Simonsen, Anne, additional

Published
2016
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50. HS1BP3 negatively regulates autophagy by modulation of phosphatidic acid levels

Author

Holland, Petter, Knaevelsrud, Helene, Soreng, Kristiane, Mathai, Benan J., Lystad, Alf Hakon, Pankiv, Serhiy, Bjorndal, Gunnveig T., Schultz, Sebastian W., Lobert, Viola H., Chan, Robin B., Zhou, Bowen, Liestol, Knut, Carlsson, Sven R., Melia, Thomas J., Di Paolo, Gilbert, Simonsen, Anne, Holland, Petter, Knaevelsrud, Helene, Soreng, Kristiane, Mathai, Benan J., Lystad, Alf Hakon, Pankiv, Serhiy, Bjorndal, Gunnveig T., Schultz, Sebastian W., Lobert, Viola H., Chan, Robin B., Zhou, Bowen, Liestol, Knut, Carlsson, Sven R., Melia, Thomas J., Di Paolo, Gilbert, and Simonsen, Anne

Abstract

A fundamental question is how autophagosome formation is regulated. Here we show that the PX domain protein HS1BP3 is a negative regulator of autophagosome formation. HS1BP3 depletion increased the formation of LC3-positive autophagosomes and degradation of cargo both in human cell culture and in zebrafish. HS1BP3 is localized to ATG16L1-and ATG9-positive autophagosome precursors and we show that HS1BP3 binds phosphatidic acid (PA) through its PX domain. Furthermore, we find the total PA content of cells to be significantly upregulated in the absence of HS1BP3, as a result of increased activity of the PA-producing enzyme phospholipase D (PLD) and increased localization of PLD1 to ATG16L1-positive membranes. We propose that HS1BP3 regulates autophagy by modulating the PA content of the ATG16L1-positive autophagosome precursor membranes through PLD1 activity and localization. Our findings provide key insights into how autophagosome formation is regulated by a novel negative-feedback mechanism on membrane lipids.

Published
2016
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