scholarly journals The yeast arrestin-related protein Bul1 is a novel actor of glucose-induced endocytosis

2018 ◽  
Vol 29 (9) ◽  
pp. 1012-1020 ◽  
Author(s):  
Junie Hovsepian ◽  
Véronique Albanèse ◽  
Michel Becuwe ◽  
Vasyl Ivashov ◽  
David Teis ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Endocytic Pathway ◽  
Yeast Cells ◽  
Monocarboxylate Transporter ◽  
Related Protein ◽  
Related Family ◽  
Nutrient Signaling ◽  
Mechanistic Basis ◽  
A Current ◽  
Glucose Availability

Yeast cells have a remarkable ability to adapt to nutritional changes in their environment. During adaptation, nutrient-signaling pathways drive the selective endocytosis of nutrient transporters present at the cell surface. A current challenge is to understand the mechanistic basis of this regulation. Transporter endocytosis is triggered by their ubiquitylation, which involves the ubiquitin ligase Rsp5 and its adaptors of the arrestin-related family (ART). This step is highly regulated by nutrient availability. For instance, the monocarboxylate transporter Jen1 is ubiquitylated, endocytosed, and degraded upon exposure to glucose. The ART protein Rod1 is required for this overall process; yet Rod1 rather controls Jen1 trafficking later in the endocytic pathway and is almost dispensable for Jen1 internalization. Thus, how glucose triggers Jen1 internalization remains unclear. We report that another ART named Bul1, but not its paralogue Bul2, contributes to Jen1 internalization. Bul1 responds to glucose availability, and preferentially acts at the plasma membrane for Jen1 internalization. Thus, multiple ARTs can act sequentially along the endocytic pathway to control transporter homeostasis. Moreover, Bul1 is in charge of Jen1 endocytosis after cycloheximide treatment, suggesting that the functional redundancy of ARTs may be explained by their ability to interact with multiple cargoes in various conditions.

scholarly journals Integrated control of transporter endocytosis and recycling by the arrestin-related protein Rod1 and the ubiquitin ligase Rsp5

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Michel Becuwe ◽  
Sébastien Léon
Keyword(s):  
Ubiquitin Ligase ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Integrated Control ◽  
Monocarboxylate Transporter ◽  
Related Protein ◽  
Endocytic Sorting ◽  
Lysosomal Targeting ◽  
Golgi Network ◽  
External Signals

After endocytosis, membrane proteins can recycle to the cell membrane or be degraded in lysosomes. Cargo ubiquitylation favors their lysosomal targeting and can be regulated by external signals, but the mechanism is ill-defined. Here, we studied the post-endocytic trafficking of Jen1, a yeast monocarboxylate transporter, using microfluidics-assisted live-cell imaging. We show that the ubiquitin ligase Rsp5 and the glucose-regulated arrestin-related trafficking adaptors (ART) protein Rod1, involved in the glucose-induced internalization of Jen1, are also required for the post-endocytic sorting of Jen1 to the yeast lysosome. This new step takes place at the trans-Golgi network (TGN), where Rod1 localizes dynamically upon triggering endocytosis. Indeed, transporter trafficking to the TGN after internalization is required for their degradation. Glucose removal promotes Rod1 relocalization to the cytosol and Jen1 deubiquitylation, allowing transporter recycling when the signal is only transient. Therefore, nutrient availability regulates transporter fate through the localization of the ART/Rsp5 ubiquitylation complex at the TGN.

Treatment of Lymphoid and Myeloid Malignancies by Immunomodulatory Drugs

2019 ◽  
Vol 19 (1) ◽  
pp. 51-78 ◽  
Author(s):  
Ota Fuchs
Keyword(s):  
Clinical Trials ◽  
Transcription Factors ◽  
Ubiquitin Ligase ◽  
Mononuclear Cells ◽  
E3 Ubiquitin Ligase ◽  
Lymphocytic Leukemia ◽  
Monocarboxylate Transporter ◽  
Immunomodulatory Drugs ◽  
Monocarboxylate Transporter 1 ◽  
Argonaute 2

Thalidomide and its derivatives (lenalidomide, pomalidomide, avadomide, iberdomide hydrochoride, CC-885 and CC-90009) form the family of immunomodulatory drugs (IMiDs). Lenalidomide (CC5013, Revlimid®) was approved by the US FDA and the EMA for the treatment of multiple myeloma (MM) patients, low or intermediate-1 risk transfusion-dependent myelodysplastic syndrome (MDS) with chromosome 5q deletion [del(5q)] and relapsed and/or refractory mantle cell lymphoma following bortezomib. Lenalidomide has also been studied in clinical trials and has shown promising activity in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). Lenalidomide has anti-inflammatory effects and inhibits angiogenesis. Pomalidomide (CC4047, Imnovid® [EU], Pomalyst® [USA]) was approved for advanced MM insensitive to bortezomib and lenalidomide. Other IMiDs are in phases 1 and 2 of clinical trials. Cereblon (CRBN) seems to have an important role in IMiDs action in both lymphoid and myeloid hematological malignancies. Cereblon acts as the substrate receptor of a cullin-4 really interesting new gene (RING) E3 ubiquitin ligase CRL4CRBN. This E3 ubiquitin ligase in the absence of lenalidomide ubiquitinates CRBN itself and the other components of CRL4CRBN complex. Presence of lenalidomide changes specificity of CRL4CRBN which ubiquitinates two transcription factors, IKZF1 (Ikaros) and IKZF3 (Aiolos), and casein kinase 1α (CK1α) and marks them for degradation in proteasomes. Both these transcription factors (IKZF1 and IKZF3) stimulate proliferation of MM cells and inhibit T cells. Low CRBN level was connected with insensitivity of MM cells to lenalidomide. Lenalidomide decreases expression of protein argonaute-2, which binds to cereblon. Argonaute-2 seems to be an important drug target against IMiDs resistance in MM cells. Lenalidomide decreases also basigin and monocarboxylate transporter 1 in MM cells. MM cells with low expression of Ikaros, Aiolos and basigin are more sensitive to lenalidomide treatment. The CK1α gene (CSNK1A1) is located on 5q32 in commonly deleted region (CDR) in del(5q) MDS. Inhibition of CK1α sensitizes del(5q) MDS cells to lenalidomide. CK1α mediates also survival of malignant plasma cells in MM. Though, inhibition of CK1α is a potential novel therapy not only in del(5q) MDS but also in MM. High level of full length CRBN mRNA in mononuclear cells of bone marrow and of peripheral blood seems to be necessary for successful therapy of del(5q) MDS with lenalidomide. While transfusion independence (TI) after lenalidomide treatment is more than 60% in MDS patients with del(5q), only 25% TI and substantially shorter duration of response with occurrence of neutropenia and thrombocytopenia were achieved in lower risk MDS patients with normal karyotype treated with lenalidomide. Shortage of the biomarkers for lenalidomide response in these MDS patients is the main problem up to now.

The yeast VPS5/GRD2 gene encodes a sorting nexin-1-like protein required for localizing membrane proteins to the late Golgi

1997 ◽  
Vol 110 (9) ◽  
pp. 1063-1072 ◽  
Author(s):  
S.F. Nothwehr ◽  
A.E. Hindes
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Localization ◽  
Endocytic Pathway ◽  
Yeast Cells ◽  
Carboxypeptidase Y ◽  
Golgi Membrane ◽  
Sorting Nexin ◽  
Vacuolar Protein ◽  
Sorting Nexin 1

Genetic analysis of late Golgi membrane protein localization in Saccharomyces cerevisiae has uncovered a large number of genes (called GRD) that are required for retention of A-ALP, a model late Golgi membrane protein. Here we describe one of the GRD genes, VPSS/GRD2, that encodes a hydrophilic protein similar to human sorting nexin-1, a protein involved in trafficking of the epidermal growth factor receptor. In yeast cells containing a vps5 null mutation the late Golgi membrane proteins A-ALP and Kex2p were rapidly mislocalized to the vacuolar membrane. A-ALP was delivered to the vacuole in vps5 mutants in a manner independent of a block in the early endocytic pathway. vps5 null mutants also exhibited defects in both vacuolar morphology and in sorting of a soluble vacuolar protein, carboxypeptidase Y. The latter defect is apparently due to an inability to localize the carboxypeptidase Y sorting receptor, Vps10p, to the Golgi since it is rapidly degraded in the vacuole in vps5 mutants. Fractionation studies indicate that Vps5p is distributed between a free cytosolic pool and a particulate fraction containing Golgi, transport vesicles, and possibly endosomes, but lacking vacuolar membranes. Immunofluorescence microscopy experiments show that the membrane-associated pool of Vps5p localizes to an endosome-like organelle that accumulates in the class E vps27 mutant. These results support a model in which Vps5p is required for retrieval of membrane proteins from a prevacuolar/late endosomal compartment back to the late Golgi apparatus.

scholarly journals Intestinal epithelial tight junction barrier regulation by autophagy-related protein ATG6/beclin 1

2019 ◽  
Vol 316 (5) ◽  
pp. C753-C765 ◽  
Author(s):  
Morgan Wong ◽  
Ashwinkumar Subramenium Ganapathy ◽  
Eric Suchanec ◽  
Laura Laidler ◽  
Thomas Ma ◽  
...  
Keyword(s):  
Tight Junction ◽  
Barrier Function ◽  
De Novo ◽  
Regulatory Protein ◽  
Endocytic Pathway ◽  
Beclin 1 ◽  
Intestinal Epithelial ◽  
Related Protein ◽  
Constitutive Function ◽  
Mouse Colon

A defective tight junction (TJ) barrier is a key pathogenic factor for inflammatory bowel disease. Previously, we have shown that autophagy, a cell survival mechanism, enhances intestinal epithelial TJ barrier function. Autophagy-related protein-6 (ATG6/beclin 1), a key protein in the autophagy pathway, also plays a role in the endocytic pathway. The constitutive role of beclin 1 in the intestinal TJ barrier is not known. In Caco-2 cells, beclin 1 was found to be coimmunoprecipitated with the TJ protein occludin and colocalized with occludin on the membrane. Treatment of Caco-2 cells with beclin 1 peptide [transactivating regulatory protein (Tat)-beclin 1] reduced TJ barrier function. Activation of beclin 1 increased occludin endocytosis and reduced total occludin protein level. In contrast, beclin 1 siRNA transfection enhanced Caco-2 TJ barrier function. In pharmacologic and genetic autophagy inhibition studies, the constitutive function of beclin 1 in the TJ barrier was found to be autophagy independent. However, de novo induction of autophagy with starvation or rapamycin prevented Tat-beclin 1-induced increase in TJ permeability and reduction in occludin level. Induction of autophagy also resulted in reduced beclin 1-occludin association. In mouse colon, beclin 1 colocalized with occludin on the epithelial membrane. Perfusion of mouse colon with beclin 1 peptide caused an increase in colonic TJ permeability that was prevented by in vivo induction of autophagy. These findings show that beclin 1 plays a constitutive, autophagy-independent role in the regulation of intestinal TJ barrier function via endocytosis of occludin. Autophagy terminates constitutive beclin 1 function in the TJ barrier and enhances the TJ barrier.

scholarly journals SIP/CacyBP promotes autophagy by regulating levels of BRUCE/Apollon, which stimulates LC3-I degradation

2019 ◽  
Vol 116 (27) ◽  
pp. 13404-13413 ◽  
Author(s):  
Tian-Xia Jiang ◽  
Jiang-Bo Zou ◽  
Qian-Qian Zhu ◽  
Cui Hua Liu ◽  
Guang-Fei Wang ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Cultured Cells ◽  
Proteasomal Degradation ◽  
Related Protein ◽  
Topoisomerase Inhibitors ◽  
Autophagosome Formation ◽  
Recycling Endosome ◽  
Proteasome Activator ◽  
Apoptosis Protein ◽  
Autophagic Degradation

BRUCE/Apollon is a membrane-associated inhibitor of apoptosis protein that is essential for viability and has ubiquitin-conjugating activity. On initiation of apoptosis, the ubiquitin ligase Nrdp1/RNF41 promotes proteasomal degradation of BRUCE. Here we demonstrate that BRUCE together with the proteasome activator PA28γ causes proteasomal degradation of LC3-I and thus inhibits autophagy. LC3-I on the phagophore membrane is conjugated to phosphatidylethanolamine to form LC3-II, which is required for the formation of autophagosomes and selective recruitment of substrates. SIP/CacyBP is a ubiquitination-related protein that is highly expressed in neurons and various tumors. Under normal conditions, SIP inhibits the ubiquitination and degradation of BRUCE, probably by blocking the binding of Nrdp1 to BRUCE. On DNA damage by topoisomerase inhibitors, Nrdp1 causes monoubiquitination of SIP and thus promotes apoptosis. However, on starvation, SIP together with Rab8 enhances the translocation of BRUCE into the recycling endosome, formation of autophagosomes, and degradation of BRUCE by optineurin-mediated autophagy. Accordingly, deletion of SIP in cultured cells reduces the autophagic degradation of damaged mitochondria and cytosolic protein aggregates. Thus, by stimulating proteasomal degradation of LC3-I, BRUCE also inhibits autophagy. Conversely, SIP promotes autophagy by blocking BRUCE-dependent degradation of LC3-I and by enhancing autophagosome formation and autophagic destruction of BRUCE. These actions of BRUCE and SIP represent mechanisms that link the regulation of autophagy and apoptosis under different conditions.

scholarly journals Disease-causing mutations in Parkin impair mitochondrial ubiquitination, aggregation, and HDAC6-dependent mitophagy

2010 ◽  
Vol 189 (4) ◽  
pp. 671-679 ◽  
Author(s):  
Joo-Yong Lee ◽  
Yoshito Nagano ◽  
J. Paul Taylor ◽  
Kah Leong Lim ◽  
Tso-Pang Yao
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Ubiquitin Ligase ◽  
Protein Aggregate ◽  
Selective Autophagy ◽  
Ubiquitin Binding ◽  
Microtubule Motor ◽  
Mechanistic Basis ◽  
Dependent Transport ◽  
Familial Parkinson’S Disease

Mutations in parkin, a ubiquitin ligase, cause early-onset familial Parkinson's disease (AR-JP). How parkin suppresses Parkinsonism remains unknown. Parkin was recently shown to promote the clearance of impaired mitochondria by autophagy, termed mitophagy. Here, we show that parkin promotes mitophagy by catalyzing mitochondrial ubiquitination, which in turn recruits ubiquitin-binding autophagic components, HDAC6 and p62, leading to mitochondrial clearance. During the process, juxtanuclear mitochondrial aggregates resembling a protein aggregate-induced aggresome are formed. The formation of these “mito-aggresome” structures requires microtubule motor-dependent transport and is essential for efficient mitophagy. Importantly, we show that AR-JP–causing parkin mutations are defective in supporting mitophagy due to distinct defects at recognition, transportation, or ubiquitination of impaired mitochondria, thereby implicating mitophagy defects in the development of Parkinsonism. Our results show that impaired mitochondria and protein aggregates are processed by common ubiquitin-selective autophagy machinery connected to the aggresomal pathway, thus identifying a mechanistic basis for the prevalence of these toxic entities in Parkinson's disease.

scholarly journals The Fission Yeast Transforming Acidic Coiled Coil–related Protein Mia1p/Alp7p Is Required for Formation and Maintenance of Persistent Microtubule-organizing Centers at the Nuclear Envelope

2006 ◽  
Vol 17 (5) ◽  
pp. 2212-2222 ◽  
Author(s):  
Liling Zheng ◽  
Cindi Schwartz ◽  
Liangmeng Wee ◽  
Snezhana Oliferenko
Keyword(s):  
Nuclear Envelope ◽  
Fission Yeast ◽  
Cell Biology ◽  
De Novo ◽  
Coiled Coil ◽  
Yeast Cells ◽  
Related Protein ◽  
Microtubule Organizing Centers ◽  
Nucleation Sites ◽  
Rich Material

Microtubule-organizing centers (MTOCs) concentrate microtubule nucleation, attachment and bundling factors and thus restrict formation of microtubule arrays in spatial and temporal manner. How MTOCs occur remains an exciting question in cell biology. Here, we show that the transforming acidic coiled coil–related protein Mia1p/Alp7p functions in emergence of large MTOCs in interphase fission yeast cells. We found that Mia1p was a microtubule-binding protein that preferentially localized to the minus ends of microtubules and was associated with the sites of microtubule attachment to the nuclear envelope. Cells lacking Mia1p exhibited less microtubule bundles. Microtubules could be nucleated and bundled but were frequently released from the nucleation sites in mia1Δ cells. Mia1p was required for stability of microtubule bundles and persistent use of nucleation sites both in interphase and postanaphase array dynamics. The γ-tubulin–rich material was not organized in large perinuclear or microtubule-associated structures in mia1Δ cells. Interestingly, absence of microtubules in dividing wild-type cells prevented appearance of large γ-tubulin–rich MTOC structures in daughters. When microtubule polymerization was allowed, MTOCs were efficiently assembled de novo. We propose a model where MTOC emergence is a self-organizing process requiring the continuous association of microtubules with nucleation sites.

scholarly journals Yeast Actin-Related Protein ARP6 Negatively RegulatesAgrobacterium-Mediated Transformation of Yeast Cell

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Yumei Luo ◽  
Zikai Chen ◽  
Detu Zhu ◽  
Haitao Tu ◽  
Shen Quan Pan
Keyword(s):  
Genetic Engineering ◽  
Large Scale ◽  
Transformation Efficiency ◽  
Genetic Diseases ◽  
Negative Regulator ◽  
Yeast Cells ◽  
Scale Production ◽  
Related Protein ◽  
Cellular Mechanisms ◽  
Eukaryotic Organisms

The yeasts, includingSaccharomyces cerevisiaeandPichia pastoris, are single-cell eukaryotic organisms that can serve as models for human genetic diseases and hosts for large scale production of recombinant proteins in current biopharmaceutical industry. Thus, efficient genetic engineering tools for yeasts are of great research and economic values.Agrobacterium tumefaciens-mediated transformation (AMT) can transfer T-DNA into yeast cells as a method for genetic engineering. However, how the T-DNA is transferred into the yeast cells is not well established yet. Here our genetic screening of yeast knockout mutants identified a yeast actin-related proteinARP6as a negative regulator of AMT.ARP6is a critical member of the SWR1 chromatin remodeling complex (SWR-C); knocking out some other components of the complex also increased the transformation efficiency, suggesting thatARP6might regulate AMT via SWR-C. Moreover, knockout ofARP6led to disruption of microtubule integrity, higher uptake and degradation of virulence proteins, and increased DNA stability inside the cells, all of which resulted in enhanced transformation efficiency. Our findings have identified molecular and cellular mechanisms regulating AMT and a potential target for enhancing the transformation efficiency in yeast cells.

scholarly journals From foodwebs to gene regulatory networks (GRNs) - weak repressions by microRNAs confer system stability

2017 ◽  
Author(s):  
Yuxin Chen ◽  
Yang Shen ◽  
Stefano Allesina ◽  
Chung-I Wu
Keyword(s):  
Regulatory Networks ◽  
Stability Control ◽  
System Stability ◽  
Yeast Cells ◽  
System Level ◽  
Main Function ◽  
Highly Expressed Genes ◽  
Gene Regulatory ◽  
Mechanistic Basis ◽  
The Stability

AbstractMore than 30% of mRNAs are repressed by microRNAs (miRNAs) but most repressions are too weak to have a phenotypic consequence. The diffuse actions have been a central conundrum in understanding the functions of miRNAs. By applying the May-Wigner theory used in foodweb studies, we show that i) weak repressions cumulatively enhance the stability of gene regulatory network (GRN), and ii) broad and weak repressions confer greater stability than a few strong ones. Transcriptome data show that yeast cells, which do not have miRNAs, use strong and non-specific mRNA degradation to stabilize their GRN; in contrast, human cells use miRNAs to increase degradation more modestly and selectively. Simulations indicate that miRNA repressions should be distributed broadly to >25% of mRNAs, in agreement with observations. As predicted, extremely highly expressed genes are avoided and transcription factors are preferred by miRNAs. In conclusion, the diffuse repression by miRNAs is likely a system-level strategy for enhancing GRN stability. This stability control may be the mechanistic basis of “canalization” (i.e., developmental homeostasis within each species), sometimes hypothesized to be a main function of miRNAs.

Sign in / Sign up

Export Citation Format

Share Document