ESCRTs and human disease

2009 ◽  
Vol 37 (1) ◽  
pp. 167-172 ◽  
Author(s):  
Suraj Saksena ◽  
Scott D. Emr
Keyword(s):  
Human Disease ◽  
Protein Sorting ◽  
Critical Role ◽  
Multivesicular Body ◽  
Human Diseases ◽  
Down Regulation ◽  
Endosomal Sorting ◽  
Retroviral Budding

The ESCRT (endosomal sorting complex required for transport) machinery plays a critical role in receptor down-regulation, retroviral budding, and other normal and pathological processes. The ESCRT components are conserved in all five major subgroups of eukaryotes. This review summarizes the growing number of links identified between ESCRT-mediated protein sorting in the MVB (multivesicular body) pathway and various human diseases.

scholarly journals New component of ESCRT-I regulates endosomal sorting complex assembly

2006 ◽  
Vol 175 (5) ◽  
pp. 815-823 ◽  
Author(s):  
Tony Chu ◽  
Ji Sun ◽  
Suraj Saksena ◽  
Scott D. Emr
Keyword(s):  
Molecular Mechanisms ◽  
Critical Role ◽  
Coiled Coil ◽  
Multivesicular Body ◽  
Stable Complex ◽  
Oligomeric State ◽  
Endosomal Sorting ◽  
Coiled Coil Domain ◽  
Retroviral Budding ◽  
Vacuolar Protein

The endosomal sorting complex required for transport (ESCRT) complexes play a critical role in receptor down-regulation and retroviral budding. Although the crystal structures of two ESCRT complexes have been determined, the molecular mechanisms underlying the assembly and regulation of the ESCRT machinery are still poorly understood. We identify a new component of the ESCRT-I complex, multivesicular body sorting factor of 12 kD (Mvb12), and demonstrate that Mvb12 binds to the coiled-coil domain of the ESCRT-I subunit vacuolar protein sorting 23 (Vps23). We show that ESCRT-I adopts an oligomeric state in the cytosol, the formation of which requires the coiled-coil domain of Vps23, as well as Mvb12. Loss of Mvb12 results in the disassembly of the ESCRT-I oligomer and the formation of a stable complex of ESCRT-I and -II in the cytosol. We propose that Mvb12 stabilizes ESCRT-I in an oligomeric, inactive state in the cytosol to ensure that the ordered recruitment and assembly of ESCRT-I and -II is spatially and temporally restricted to the surface of the endosome after activation of the MVB sorting reaction.

Peroxisome biogenesis and the formation of multivesicular peroxisomes during tombusvirus infection: a role for ESCRT?This review is one of a selection of papers published in the Special Issue on Plant Cell Biology.

2006 ◽  
Vol 84 (4) ◽  
pp. 551-564 ◽  
Author(s):  
Robert T. Mullen ◽  
Andrew W. McCartney ◽  
C. Robb Flynn ◽  
Graham S.T. Smith
Keyword(s):  
Cell Biology ◽  
Molecular Mechanisms ◽  
Protein Sorting ◽  
Multivesicular Body ◽  
Peroxisomal Membrane ◽  
Viral Pathogens ◽  
Endosomal Sorting ◽  
Metabolic Functions ◽  
Membrane Bound ◽  
Vacuolar Protein

Peroxisomes are highly dynamic organelles with regard to their metabolic functions, shapes, distribution, movements, and biogenesis. They are also important as sites for the development of some viral pathogens. It has long been known that certain members of the tombusvirus family recruit peroxisomes for viral RNA replication and that this process is accompanied by dramatic changes in peroxisome morphology, the most remarkable of which is the extensive inward vesiculation of the peroxisomal boundary membrane leading to the formation of a peroxisomal multivesicular body (pMVB). While it is unclear how the internal vesicles of a pMVB form, they appear to serve in effectively concentrating viral membrane-bound replication complexes and protecting nascent viral RNAs from host-cell defences. Here, we review briefly the biogenesis of peroxisomes and pMVBs and discuss recent studies that have begun to shed light on how components of the tombusvirus replicase exploit the molecular mechanisms involved in peroxisome membrane protein sorting. We also address the question of what controls invagination and vesicle formation at the peroxisomal membrane during pMVB biogenesis. We propose that tombusviruses exploit protein constituents of the class E vacuolar protein-sorting pathway referred to as ESCRT (endosomal sorting complex required for transport) in the formation of pMVBs. This new pMVB–ESCRT hypothesis reconciles current paradigms of pMVB biogenesis with the role of ESCRT in endosomal multivesicular body formation and the ability of enveloped RNA viruses, including HIV, to appropriate the ESCRT machinery to execute their budding programme from cells.

scholarly journals MITD1 is recruited to midbodies by ESCRT-III and participates in cytokinesis

2012 ◽  
Vol 23 (22) ◽  
pp. 4347-4361 ◽  
Author(s):  
Seongju Lee ◽  
Jaerak Chang ◽  
Benoît Renvoisé ◽  
Anita Tipirneni ◽  
Sarah Yang ◽  
...  
Keyword(s):  
Critical Role ◽  
Multivesicular Body ◽  
Strong Interactions ◽  
Body Protein ◽  
Endosomal Sorting ◽  
Cellular Processes ◽  
Viral Budding ◽  
Membrane Fission ◽  
Downstream Effects ◽  
Trafficking Molecules

Diverse cellular processes, including multivesicular body formation, cytokinesis, and viral budding, require the sequential functions of endosomal sorting complexes required for transport (ESCRTs) 0 to III. Of these multiprotein complexes, ESCRT-III in particular plays a key role in mediating membrane fission events by forming large, ring-like helical arrays. A number of proteins playing key effector roles, most notably the ATPase associated with diverse cellular activities protein VPS4, harbor present in microtubule-interacting and trafficking molecules (MIT) domains comprising asymmetric three-helical bundles, which interact with helical MIT-interacting motifs in ESCRT-III subunits. Here we assess comprehensively the ESCRT-III interactions of the MIT-domain family member MITD1 and identify strong interactions with charged multivesicular body protein 1B (CHMP1B), CHMP2A, and increased sodium tolerance-1 (IST1). We show that these ESCRT-III subunits are important for the recruitment of MITD1 to the midbody and that MITD1 participates in the abscission phase of cytokinesis. MITD1 also dimerizes through its C-terminal domain. Both types of interactions appear important for the role of MITD1 in negatively regulating the interaction of IST1 with VPS4. Because IST1 binding in turn regulates VPS4, MITD1 may function through downstream effects on the activity of VPS4, which plays a critical role in the processing and remodeling of ESCRT filaments in abscission.

scholarly journals Vacuolar Protein Sorting Genes Regulate Mat Formation in Saccharomyces cerevisiae by Flo11p-Dependent and -Independent Mechanisms

2011 ◽  
Vol 10 (11) ◽  
pp. 1516-1526 ◽  
Author(s):  
Neha Sarode ◽  
Bethany Miracle ◽  
Xin Peng ◽  
Owen Ryan ◽  
Todd B. Reynolds
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Sorting ◽  
Multivesicular Body ◽  
Invasive Growth ◽  
Independent Manner ◽  
Content Type ◽  
Endosomal Sorting ◽  
Vacuolar Protein ◽  
Transport Complex ◽  
Standard Density

ABSTRACT Saccharomyces cerevisiae generates complex biofilms called mats on low-density (0.3%) agar plates. The mats can be morphologically divided into two regions: (i) hub, the interior region characterized by the presence of wrinkles and channels, and (ii) rim, the smooth periphery. Formation of mats depends on the adhesin Flo11p, which is also required for invasive growth, a phenotype in which the S. cerevisiae yeasts grow as chains of cells that dig into standard-density (2%) agar plates. Although both invasive growth and mat formation depend on Flo11p, mutations that perturb the multivesicular body (MVB) protein sorting pathway inhibit mat formation in a FLO11 -independent manner. These mutants, represented by vps27 Δ, disrupt mat formation but do not affect invasive growth, FLO11 gene or protein expression, or Flo11p localization. In contrast, an overlapping subset of MVB mutants (represented by ESCRT [endosomal sorting complex required for transport] complex genes such as VPS25 ) interrupt the Rim101p signal transduction cascade, which is required for FLO11 expression, and thus block both invasive growth and mat formation. In addition, this report shows that mature Flo11p is covalently associated with the cell wall and shed into the extracellular matrix of the growing mat.

scholarly journals Human ESCRT-II Complex and Its Role in Human Immunodeficiency Virus Type 1 Release

2006 ◽  
Vol 80 (19) ◽  
pp. 9465-9480 ◽  
Author(s):  
Charles Langelier ◽  
Uta K. von Schwedler ◽  
Robert D. Fisher ◽  
Ivana De Domenico ◽  
Paul L. White ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Protein Sorting ◽  
Growth Factor Receptor ◽  
Multivesicular Body ◽  
Vesicle Formation ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The budding of many enveloped RNA viruses, including human immunodeficiency virus type 1 (HIV-1), requires some of the same cellular machinery as vesicle formation at the multivesicular body (MVB). In Saccharomyces cerevisiae, the ESCRT-II complex performs a central role in MVB protein sorting and vesicle formation, as it is recruited by the upstream ESCRT-I complex and nucleates assembly of the downstream ESCRT-III complex. Here, we report that the three subunits of human ESCRT-II, EAP20, EAP30, and EAP45, have a number of properties in common with their yeast orthologs. Specifically, EAP45 bound ubiquitin via its N-terminal GRAM-like ubiquitin-binding in EAP45 (GLUE) domain, both EAP45 and EAP30 bound the C-terminal domain of TSG101/ESCRT-I, and EAP20 bound the N-terminal half of CHMP6/ESCRT-III. Consistent with its expected role in MVB vesicle formation, (i) human ESCRT-II localized to endosomal membranes in a VPS4-dependent fashion and (ii) depletion of EAP20/ESCRT-II and CHMP6/ESCRT-III inhibited lysosomal targeting and downregulation of the epidermal growth factor receptor, albeit to a lesser extent than depletion of TSG101/ESCRT-I. Nevertheless, HIV-1 release and infectivity were not reduced by efficient small interfering RNA depletion of EAP20/ESCRT-II or CHMP6/ESCRT-III. These observations indicate that there are probably multiple pathways for protein sorting/MVB vesicle formation in human cells and that HIV-1 does not utilize an ESCRT-II-dependent pathway to leave the cell.

scholarly journals MARK2 phosphorylates eIF2α in response to proteotoxic stress

PLoS Biology ◽  
2021 ◽  
Vol 19 (3) ◽  
pp. e3001096
Author(s):  
Yu-Ning Lu ◽  
Sarah Kavianpour ◽  
Tao Zhang ◽  
Xumei Zhang ◽  
Dao Nguyen ◽  
...  
Keyword(s):  
Stress Responses ◽  
Protein Misfolding ◽  
Critical Role ◽  
Heat Shock Protein 90 ◽  
Human Diseases ◽  
Initiation Factor ◽  
Translation Regulation ◽  
Proteotoxic Stress ◽  
Initiation Factor 2 ◽  
Lateral Sclerosis

The regulation of protein synthesis is essential for maintaining cellular homeostasis, especially during stress responses, and its dysregulation could underlie the development of human diseases. The critical step during translation regulation is the phosphorylation of eukaryotic initiation factor 2 alpha (eIF2α). Here we report the identification of a direct kinase of eIF2α, microtubule affinity-regulating kinase 2 (MARK2), which phosphorylates eIF2α in response to proteotoxic stress. The activity of MARK2 was confirmed in the cells lacking the 4 previously known eIF2α kinases. MARK2 itself was found to be a substrate of protein kinase C delta (PKCδ), which serves as a sensor for protein misfolding stress through a dynamic interaction with heat shock protein 90 (HSP90). Both MARK2 and PKCδ are activated via phosphorylation in proteotoxicity-associated neurodegenerative mouse models and in human patients with amyotrophic lateral sclerosis (ALS). These results reveal a PKCδ-MARK2-eIF2α cascade that may play a critical role in cellular proteotoxic stress responses and human diseases.

scholarly journals Cargo-selective endosomal sorting for retrieval to the Golgi requires retromer

2004 ◽  
Vol 165 (1) ◽  
pp. 111-122 ◽  
Author(s):  
Matthew N.J. Seaman
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Multivesicular Body ◽  
Carboxypeptidase Y ◽  
Reporter Protein ◽  
Rapid Degradation ◽  
Endosomal Sorting ◽  
Lysosome Biogenesis ◽  
Golgi Transport ◽  
Efficient Retrieval

fEndosome-to-Golgi retrieval of the mannose 6-phosphate receptor (MPR) is required for lysosome biogenesis. Currently, this pathway is poorly understood. Analyses in yeast identified a complex of proteins called “retromer” that is essential for endosome-to-Golgi retrieval of the carboxypeptidase Y receptor Vps10p. Retromer comprises five distinct proteins: Vps35p, 29p, 26p, 17p, and 5p, which are conserved in mammals. Here, we show that retromer is required for the efficient retrieval of the cation-independent MPR (CI-MPR). Cells lacking mammalian VPS26 fail to retrieve the CI-MPR, resulting in either rapid degradation of or mislocalization to the plasma membrane. We have localized mVPS26 to multivesicular body endosomes by electron microscopy, and through the use of CD8 reporter protein constructs have examined the effect of loss of mVPS26 upon the trafficking of membrane proteins that cycle between the endosome and the Golgi. The data presented here support the hypothesis that retromer performs a selective function in endosome-to-Golgi transport, mediating retrieval of the CI-MPR, but not furin.

scholarly journals HOTAIR: An Oncogenic Long Non-Coding RNA in Human Cancer

2018 ◽  
Vol 47 (3) ◽  
pp. 893-913 ◽  
Author(s):  
Qing Tang ◽  
Swei Sunny Hann
Keyword(s):  
Drug Resistance ◽  
Human Cancer ◽  
Critical Role ◽  
Stem Cell Differentiation ◽  
Human Diseases ◽  
Biological Functions ◽  
Protein Coding ◽  
Non Coding Rna ◽  
And Function ◽  
Long Non Coding Rna

Long non-coding RNAs (LncRNAs) represent a novel class of noncoding RNAs that are longer than 200 nucleotides without protein-coding potential and function as novel master regulators in various human diseases, including cancer. Accumulating evidence shows that lncRNAs are dysregulated and implicated in various aspects of cellular homeostasis, such as proliferation, apoptosis, mobility, invasion, metastasis, chromatin remodeling, gene transcription, and post-transcriptional processing. However, the mechanisms by which lncRNAs regulate various biological functions in human diseases have yet to be determined. HOX antisense intergenic RNA (HOTAIR) is a recently discovered lncRNA and plays a critical role in various areas of cancer, such as proliferation, survival, migration, drug resistance, and genomic stability. In this review, we briefly introduce the concept, identification, and biological functions of HOTAIR. We then describe the involvement of HOTAIR that has been associated with tumorigenesis, growth, invasion, cancer stem cell differentiation, metastasis, and drug resistance in cancer. We also discuss emerging insights into the role of HOTAIR as potential biomarkers and therapeutic targets for novel treatment paradigms in cancer.

scholarly journals TarGo: network based target gene selection system for human disease related mouse models

2019 ◽  
Vol 35 (1) ◽  
Author(s):  
Daejin Hyung ◽  
Ann-Marie Mallon ◽  
Dong Soo Kyung ◽  
Soo Young Cho ◽  
Je Kyung Seong
Keyword(s):  
Mouse Models ◽  
Network Topology ◽  
Human Disease ◽  
Target Gene ◽  
Gene Selection ◽  
Genetically Engineered ◽  
Human Diseases ◽  
Selection System ◽  
Genetically Engineered Mouse Models ◽  
Disease Signatures

Abstract Genetically engineered mouse models are used in high-throughput phenotyping screens to understand genotype-phenotype associations and their relevance to human diseases. However, not all mutant mouse lines with detectable phenotypes are associated with human diseases. Here, we propose the “Target gene selection system for Genetically engineered mouse models” (TarGo). Using a combination of human disease descriptions, network topology, and genotype-phenotype correlations, novel genes that are potentially related to human diseases are suggested. We constructed a gene interaction network using protein-protein interactions, molecular pathways, and co-expression data. Several repositories for human disease signatures were used to obtain information on human disease-related genes. We calculated disease- or phenotype-specific gene ranks using network topology and disease signatures. In conclusion, TarGo provides many novel features for gene function prediction.

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