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Full-Text Articles in Cell Biology

A Critical Role Of Vmp1 In Lipoprotein Secretion, Hideaki Morishita, Yan G. Zhao, Norito Tamura, Taki Nishimura, Yuki Kanda, Yuriko Sakamaki, Mitsuyo Okazaki, Dongfang Li, Noboru Mizushima Sep 2019

A Critical Role Of Vmp1 In Lipoprotein Secretion, Hideaki Morishita, Yan G. Zhao, Norito Tamura, Taki Nishimura, Yuki Kanda, Yuriko Sakamaki, Mitsuyo Okazaki, Dongfang Li, Noboru Mizushima

Open Access Articles

Lipoproteins are lipid-protein complexes that are primarily generated and secreted from the intestine, liver, and visceral endoderm and delivered to peripheral tissues. Lipoproteins, which are assembled in the endoplasmic reticulum (ER) membrane, are released into the ER lumen for secretion, but its mechanism remains largely unknown. Here, we show that the release of lipoproteins from the ER membrane requires VMP1, an ER transmembrane protein essential for autophagy and certain types of secretion. Loss of vmp1, but not other autophagy-related genes, in zebrafish causes lipoprotein accumulation in the intestine and liver. Vmp1 deficiency in mice also leads to lipid accumulation in ...


Extensive Ribosome And Rf2 Rearrangements During Translation Termination, Egor Svidritskiy, Gabriel Demo, Anna B. Loveland, Chen Xu, Andrei A. Korostelev Sep 2019

Extensive Ribosome And Rf2 Rearrangements During Translation Termination, Egor Svidritskiy, Gabriel Demo, Anna B. Loveland, Chen Xu, Andrei A. Korostelev

Open Access Articles

Protein synthesis ends when a ribosome reaches an mRNA stop codon. Release factors (RFs) decode the stop codon, hydrolyze peptidyl-tRNA to release the nascent protein, and then dissociate to allow ribosome recycling. To visualize termination by RF2, we resolved a cryo-EM ensemble of E. coli 70S*RF2 structures at up to 3.3 A in a single sample. Five structures suggest a highly dynamic termination pathway. Upon peptidyl-tRNA hydrolysis, the CCA end of deacyl-tRNA departs from the peptidyl transferase center. The catalytic GGQ loop of RF2 is rearranged into a long beta-hairpin that plugs the peptide tunnel, biasing a nascent ...


Llc Tumor Cells-Derivated Factors Reduces Adipogenesis In Co-Culture System, Magno Alves Lopes, Felipe Oliveira Franco, Felipe Henriques, Sidney Barnabe Peres, Miguel Luiz Batista Jr. Jul 2018

Llc Tumor Cells-Derivated Factors Reduces Adipogenesis In Co-Culture System, Magno Alves Lopes, Felipe Oliveira Franco, Felipe Henriques, Sidney Barnabe Peres, Miguel Luiz Batista Jr.

Open Access Articles

Cancer cachexia (CC) is a multifactorial syndrome with an unknown etiology. The primary symptom is the progressive reduction of the body weight. Recently, down-regulation of adipogenic and lipogenic genes were demonstrated to be early affected during cachexia progression in adipose tissue (AT), resulting in AT remodeling. Thus, this study aimed to evaluate in a co-culture system the influence of the Lewis Lung Carcinoma (LLC) tumor cells (c/c-LLC) in an established pre-adipocyte cell line 3T3-L1 adipogenic capacity. c/c-LLC in the presence of 3T3-L1 caused a reduction in lipids accumulation, suggesting that secretory tumor cells products may affect adipogenesis. Interestingly ...


The Histone H3k9 Demethylase Kdm3a Promotes Anoikis By Transcriptionally Activating Pro-Apoptotic Genes Bnip3 And Bnip3l, Victoria E. Pedanou, Stephane Gobeil, Sebastien Tabaries, Tessa M. Simone, Lihua Julie Zhu, Peter M. Siegel, Michael R. Green Jul 2016

The Histone H3k9 Demethylase Kdm3a Promotes Anoikis By Transcriptionally Activating Pro-Apoptotic Genes Bnip3 And Bnip3l, Victoria E. Pedanou, Stephane Gobeil, Sebastien Tabaries, Tessa M. Simone, Lihua Julie Zhu, Peter M. Siegel, Michael R. Green

Open Access Articles

Epithelial cells that lose attachment to the extracellular matrix undergo a specialized form of apoptosis called anoikis. Here, using large-scale RNA interference (RNAi) screening, we find that KDM3A, a histone H3 lysine 9 (H3K9) mono- and di-demethylase, plays a pivotal role in anoikis induction. In attached breast epithelial cells, KDM3A expression is maintained at low levels by integrin signaling. Following detachment, integrin signaling is decreased resulting in increased KDM3A expression. RNAi-mediated knockdown of KDM3A substantially reduces apoptosis following detachment and, conversely, ectopic expression of KDM3A induces cell death in attached cells. We find that KDM3A promotes anoikis through transcriptional activation ...


Ggggcc Microsatellite Rna Is Neuritically Localized, Induces Branching Defects, And Perturbs Transport Granule Function, Alondra Schweizer Burguete, Sandra Almeida, Fen-Biao Gao, Robert Kalb, Michael R. Akins, Nancy M. Bonini Dec 2015

Ggggcc Microsatellite Rna Is Neuritically Localized, Induces Branching Defects, And Perturbs Transport Granule Function, Alondra Schweizer Burguete, Sandra Almeida, Fen-Biao Gao, Robert Kalb, Michael R. Akins, Nancy M. Bonini

Open Access Articles

Microsatellite expansions are the leading cause of numerous neurodegenerative disorders. Here we demonstrate that GGGGCC and CAG microsatellite repeat RNAs associated with C9orf72 in ALS/FTD and with polyglutamine diseases, respectively, localize to neuritic granules that undergo active transport into distal neuritic segments. In cultured mammalian spinal cord neurons, the presence of neuritic GGGGCC repeat RNA correlates with neuronal branching defects and the repeat RNA localizes to granules that label with FMRP, a transport granule component. Using a Drosophila GGGGCC expansion disease model, we characterize dendritic branching defects that are modulated by FMRP and Orb2. The human orthologues of these ...


Near-Infrared Photoactivatable Control Of Ca Signaling And Optogenetic Immunomodulation, Lian He, Yuanwei Zhang, Guolin Ma, Peng Tan, Zhan Jun Li, Shengbing Zhang, Xiang Wu, Ji Jing, Shaohai Fang, Lijuan Zhou, Youjun Wang, Yun Huang, Patrick Hogan, Gang Han, Yubin Zhou Dec 2015

Near-Infrared Photoactivatable Control Of Ca Signaling And Optogenetic Immunomodulation, Lian He, Yuanwei Zhang, Guolin Ma, Peng Tan, Zhan Jun Li, Shengbing Zhang, Xiang Wu, Ji Jing, Shaohai Fang, Lijuan Zhou, Youjun Wang, Yun Huang, Patrick Hogan, Gang Han, Yubin Zhou

Open Access Articles

The application of current channelrhodopsin-based optogenetic tools is limited by the lack of strict ion selectivity and the inability to extend the spectra sensitivity into the near-infrared (NIR) tissue transmissible range. Here we present an NIR-stimulable optogenetic platform (termed "Opto-CRAC") that selectively and remotely controls Ca2+ oscillations and Ca2+-responsive gene expression to regulate the function of non-excitable cells, including T lymphocytes, macrophages and dendritic cells. When coupled to upconversion nanoparticles, the optogenetic operation window is shifted from the visible range to NIR wavelengths to enable wireless photoactivation of Ca2+-dependent signaling and optogenetic modulation of immunoinflammatory responses. In a ...