@article {64987, title = {NDP52 tunes cortical actin interaction with astral microtubules for accurate spindle orientation.}, journal = {Cell Research}, volume = {29}, year = {2019}, month = {2019 Jun 14}, pages = {666-79}, abstract = {

Oriented cell divisions are controlled by a conserved molecular cascade involving Gαi, LGN, and NuMA. Here, we show that NDP52 regulates spindle orientation via remodeling the polar cortical actin cytoskeleton. siRNA-mediated NDP52 suppression surprisingly revealed a ring-like compact subcortical F-actin architecture surrounding the spindle in prophase/prometaphase cells, which resulted in severe defects of astral microtubule growth and an aberrant spindle orientation. Remarkably, NDP52 recruited the actin assembly factor N-WASP and regulated the dynamics of the subcortical F-actin ring in mitotic cells. Mechanistically, NDP52 was found to bind to phosphatidic acid-containing vesicles, which absorbed cytoplasmic N-WASP to regulate local filamentous actin growth at the polar cortex. Our TIRFM analyses revealed that NDP52-containing vesicles anchored N-WASP and shortened the length of actin filaments in vitro. Based on these results we propose that NDP52-containing vesicles regulate cortical actin dynamics through N-WASP to accomplish a spatiotemporal regulation between astral microtubules and the actin network for proper spindle orientation and precise chromosome segregation. In this way, intracellular vesicles cooperate with microtubules and actin filaments to regulate proper mitotic progression. Since NDP52 is absent from yeast, we reason that metazoans have evolved an elaborate spindle positioning machinery to ensure accurate chromosome segregation in mitosis.

}, issn = {1748-7838}, doi = {10.1038/s41422-019-0189-9}, author = {Yu, Huijuan and Yang, Fengrui and Dong, Peng and Liao, Shanhui and Liu, Wei R and Zhao, Gangyin and Qin, Bo and Dou, Zhen and Liu, Zhe and Liu, Wei and Zang, Jianye and Lippincott-Schwartz, Jennifer and Liu, Xing and Yao, Xuebiao} } @article {47620, title = {Deacetylation of nuclear LC3 drives autophagy initiation under starvation.}, journal = {Molecular cell}, volume = {57}, year = {2015}, month = {2015 Feb 5}, pages = {456-66}, abstract = {

Shuttling of macromolecules between different cellular compartments helps regulate the timing and extent of different cellular activities. Here, we report that LC3, a key initiator of autophagy that cycles between the nucleus and cytoplasm, becomes selectively activated in the nucleus during starvation through deacetylation by the nuclear deacetylase Sirt1. Deacetylation of LC3 at K49 and K51 by Sirt1 allows LC3 to interact with the nuclear protein DOR and return to the cytoplasm with DOR, where it is able to bind Atg7 and other autophagy factors and undergo phosphatidylethanolamine conjugation to preautophagic membranes. The association of deacetylated LC3 with autophagic factors shifts LC3{\textquoteright}s distribution from the nucleus toward the cytoplasm. Thus, an acetylation-deacetylation cycle ensures that LC3 effectively redistributes in an activated form from nucleus to cytoplasm, where it plays a central role in autophagy to enable the cell to cope with the lack of external nutrients.

}, keywords = {Acetylation, Autophagy, Cell Nucleus, Cytoplasm, HEK293 Cells, Hela Cells, Humans, Lysine, Microscopy, Confocal, Microtubule-Associated Proteins, Sirtuin 1, Ubiquitin-Activating Enzymes}, issn = {1097-4164}, doi = {10.1016/j.molcel.2014.12.013}, author = {Huang, Rui and Xu, Yinfeng and Wan, Wei and Shou, Xin and Qian, Jiali and You, Zhiyuan and Liu, Bo and Chang, Chunmei and Zhou, Tianhua and Lippincott-Schwartz, Jennifer and Liu, Wei} } @article {47686, title = {The open reading frame 3a protein of severe acute respiratory syndrome-associated coronavirus promotes membrane rearrangement and cell death.}, journal = {Journal of virology}, volume = {84}, year = {2010}, month = {2010 Jan}, pages = {1097-109}, abstract = {

The genome of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains eight open reading frames (ORFs) that encode novel proteins. These accessory proteins are dispensable for in vitro and in vivo replication and thus may be important for other aspects of virus-host interactions. We investigated the functions of the largest of the accessory proteins, the ORF 3a protein, using a 3a-deficient strain of SARS-CoV. Cell death of Vero cells after infection with SARS-CoV was reduced upon deletion of ORF 3a. Electron microscopy of infected cells revealed a role for ORF 3a in SARS-CoV induced vesicle formation, a prominent feature of cells from SARS patients. In addition, we report that ORF 3a is both necessary and sufficient for SARS-CoV-induced Golgi fragmentation and that the 3a protein accumulates and localizes to vesicles containing markers for late endosomes. Finally, overexpression of ADP-ribosylation factor 1 (Arf1), a small GTPase essential for the maintenance of the Golgi apparatus, restored Golgi morphology during infection. These results establish an important role for ORF 3a in SARS-CoV-induced cell death, Golgi fragmentation, and the accumulation of intracellular vesicles.

}, keywords = {ADP-Ribosylation Factor 1, Animals, Cell Death, Cell Membrane, Cercopithecus aethiops, Cytoplasmic Vesicles, Gene Deletion, Golgi Apparatus, Host-Pathogen Interactions, Humans, SARS Virus, Transfection, Vero Cells, Viral Structural Proteins}, issn = {1098-5514}, doi = {10.1128/JVI.01662-09}, author = {Freundt, Eric C and Yu, Li and Goldsmith, Cynthia S and Welsh, Sarah and Cheng, Aaron and Yount, Boyd and Liu, Wei and Frieman, Matthew B and Buchholz, Ursula J and Screaton, Gavin R and Lippincott-Schwartz, Jennifer and Zaki, Sherif R and Xu, Xiao-Ning and Baric, Ralph S and Subbarao, Kanta and Lenardo, Michael J} }