Cellular communication processes are highly dynamic and mediated, at least in part, by contacts between various membrane structures. The endoplasmic reticulum (ER), the major biosynthetic organelle of the cell, establishes an extensive network with other membrane structures to regulate the transport of intracellular molecules. Vacuole membrane protein 1 (VMP1), an ER-localized metazoan-specific protein, plays important roles in the formation of autophagosomes and communication between the ER and other organelles, including mitochondria, autophagosome precursor membranes, Golgi, lipid droplets, and endosomes. Increasing evidence has indicated that autophagy and ER-membrane communication at membrane contact sites are closely related to neurodegenerative disorders, such as Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. In this review, we summarize the roles of VMP1 in autophagy and ER-membrane contacts and discuss their potential implications in neurodegenerative disorders.
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http://dx.doi.org/10.3389/fnmol.2020.00042 | DOI Listing |
Autophagy
January 2025
Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.
The synthesis of membrane and secreted proteins is safeguarded by an endoplasmic reticulum-associated ribosome quality control (ER-RQC) that promotes the disposal of defective translation products by the proteasome or via a lysosome-dependent pathway involving the degradation of portions of the ER by macroautophagy (reticulophagy). The UFMylation of RPL26 on ER-stalled ribosomes is essential for activating the ER-RQC and reticulophagy. Here, we report that the viral deubiquitinase (vDUB) encoded in the N-terminal domain of the Epstein-Barr virus (EBV) large tegument protein BPLF1 hinders the UFMylation of RPL26 on ribosomes that stall at the ER, promotes the stabilization of ER-RQC substrates, and inhibits reticulophagy.
View Article and Find Full Text PDFSci Rep
October 2024
Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA.
The acetylation of autophagy protein 9 A (ATG9A) in the lumen of the endoplasmic reticulum (ER) by ATase1 and ATase2 regulates the induction of reticulophagy. Analysis of the ER-specific ATG9A interactome identified calreticulin (CALR), an ER luminal Ca-binding chaperone, as key for ATG9A activity. Specifically, if acetylated, ATG9A is sequestered by CALR and prevented from engaging FAM134B and SEC62.
View Article and Find Full Text PDFCell Rep
September 2024
Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland. Electronic address:
Autophagy initiation is regulated by the ULK1 kinase complex. To gain insights into functions of the holo-complex, we generated a deep interactome by combining affinity purification- and proximity labeling-mass spectrometry of all four complex members: ULK1, ATG13, ATG101, and RB1CC1/FIP200. Under starvation conditions, the ULK1 complex interacts with several protein and lipid kinases and phosphatases, implying the formation of a signalosome.
View Article and Find Full Text PDFFront Mol Neurosci
July 2024
Department of Neurology, University of Utah, Salt Lake City, UT, United States.
The cGAS-STING innate immunity pathway and the SREBP-activated cholesterol and fatty acid synthesis pathway are abnormally co-regulated in neurodegenerative disease. Activation of STING signaling occurs at the endoplasmic reticulum (ER) membrane with STING anchored by INSIG1 along with SREBP and the sterol-bound SREBP cleavage activating protein (SCAP) when sterols are in abundance. When sterols are low, the INSIG-dependent STING pathway is inactivated and the SREBP-SCAP complex is translocated to the Golgi where SREBP is cleaved and translocated to the nucleus to transactivate genes for cholesterol and fatty acid synthesis.
View Article and Find Full Text PDFJ Neurosci
August 2024
Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53706
Mitochondrial population maintenance in neurons is essential for neuron function and survival. Contact sites between mitochondria and the endoplasmic reticulum (ER) are poised to regulate mitochondrial homeostasis in neurons. These contact sites can facilitate transfer of calcium and lipids between the organelles and have been shown to regulate aspects of mitochondrial dynamics.
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