Močové extracelulární vezikuly (uEVs) představují slibný nástroj pro neinvazivní diagnostiku a monitorování onemocnění ledvin. Tyto vezikuly, secernované buňkami ledvin, obsahují biomolekuly odrážející stav mateřských buněk. Výzkum se zaměřuje na využití uEVs jako biomarkerů pro chronická onemocnění ledvin, akutní poškození ledvin, diabetickou nefropatii a monitorování po transplantaci ledvin. Kromě diagnostického potenciálu jsou uEVs zkoumány pro terapeutické aplikace v regeneraci ledvinové tkáně. Přes výzvy v standardizaci izolačních a analytických metod uEVs, pokrok ve vývoji metod charakterizace uEVs podporuje jejich klinické využití.
Urinary extracellular vesicles (uEVs) represent a promising tool for non-invasive diagnosis and monitoring of kidney disease. These vesicles, secreted by kidney cells, contain biomolecules reflecting the status of the parent cells. Research focuses on using uEVs as biomarkers for chronic kidney disease, acute kidney injury, diabetic nephropathy and monitoring kidney transplantation. In addition to diagnostic potential, uEVs are being investigated for therapeutic applications in kidney tissue regeneration. Despite challenges in standardizing uEVs isolation and analysis methods, progress in the development of uEVs characterization methods supports their clinical use.
Monovalent-cation homeostasis, crucial for all living cells, is ensured by the activity of various types of ion transport systems located either in the plasma membrane or in the membranes of organelles. A key prerequisite for the functioning of ion-transporting proteins is their proper trafficking to the target membrane. The cornichon family of COPII cargo receptors is highly conserved in eukaryotic cells. By simultaneously binding their cargoes and a COPII-coat subunit, cornichons promote the incorporation of cargo proteins into the COPII vesicles and, consequently, the efficient trafficking of cargoes via the secretory pathway. In this review, we summarize current knowledge about cornichon proteins (CNIH/Erv14), with an emphasis on yeast and mammalian cornichons and their role in monovalent-cation homeostasis. Saccharomyces cerevisiae cornichon Erv14 serves as a cargo receptor of a large portion of plasma-membrane proteins, including several monovalent-cation transporters. By promoting the proper targeting of at least three housekeeping ion transport systems, Na+, K+/H+ antiporter Nha1, K+ importer Trk1 and K+ channel Tok1, Erv14 appears to play a complex role in the maintenance of alkali-metal-cation homeostasis. Despite their connection to serious human diseases, the repertoire of identified cargoes of mammalian cornichons is much more limited. The majority of current information is about the structure and functioning of CNIH2 and CNIH3 as auxiliary subunits of AMPAR multi-protein complexes. Based on their unique properties and easy genetic manipulation, we propose yeast cells to be a useful tool for uncovering a broader spectrum of human cornichons ́ cargoes.
- MeSH
- COP-Coated Vesicles metabolism MeSH
- Homeostasis physiology MeSH
- Ion Transport physiology MeSH
- Humans MeSH
- Membrane Proteins metabolism MeSH
- Cation Transport Proteins metabolism MeSH
- Saccharomyces cerevisiae Proteins metabolism genetics MeSH
- Saccharomyces cerevisiae * metabolism MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Erv14, a conserved cargo receptor of COPII vesicles, helps the proper trafficking of many but not all transporters to the yeast plasma membrane, for example, three out of five alkali-metal-cation transporters in Saccharomyces cerevisiae. Among them, the Nha1 cation/proton antiporter, which participates in cell cation and pH homeostasis, is a large membrane protein (985 aa) possessing a long hydrophilic C-terminus (552 aa) containing six conserved regions (C1-C6) with unknown function. A short Nha1 version, lacking almost the entire C-terminus, still binds to Erv14 but does not need it to be targeted to the plasma membrane. Comparing the localization and function of ScNha1 variants shortened at its C-terminus in cells with or without Erv14 reveals that only ScNha1 versions possessing the complete C5 region are dependent on Erv14. In addition, our broad evolutionary conservation analysis of fungal Na+ /H+ antiporters identified new conserved regions in their C-termini, and our experiments newly show C5 and other, so far unknown, regions of the C-terminus, to be involved in the functionality and substrate specificity of ScNha1. Taken together, our results reveal that also relatively small hydrophilic parts of some yeast membrane proteins underlie their need to interact with the Erv14 cargo receptor.
- MeSH
- Antiporters genetics metabolism MeSH
- Cell Membrane metabolism MeSH
- COP-Coated Vesicles genetics metabolism MeSH
- Endoplasmic Reticulum metabolism MeSH
- Membrane Proteins metabolism physiology MeSH
- Cation Transport Proteins metabolism MeSH
- Saccharomyces cerevisiae Proteins genetics metabolism physiology MeSH
- Saccharomyces cerevisiae metabolism MeSH
- Sodium metabolism MeSH
- Protein Transport MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The Arf GTPase controls formation of the COPI vesicle coat. Recent structural models of COPI revealed the positioning of two Arf1 molecules in contrasting molecular environments. Each of these pockets for Arf1 is expected to also accommodate an Arf GTPase-activating protein (ArfGAP). Structural evidence and protein interactions observed between isolated domains indirectly suggest that each niche preferentially recruits one of the two ArfGAPs known to affect COPI, i.e. Gcs1/ArfGAP1 and Glo3/ArfGAP2/3, although only partial structures are available. The functional role of the unique non-catalytic domain of either ArfGAP has not been integrated into the current COPI structural model. Here, we delineate key differences in the consequences of triggering GTP hydrolysis through the activity of one versus the other ArfGAP. We demonstrate that Glo3/ArfGAP2/3 specifically triggers Arf1 GTP hydrolysis impinging on the stability of the COPI coat. We show that the Snf1 kinase complex, the yeast homologue of AMP-activated protein kinase (AMPK), phosphorylates the region of Glo3 that is crucial for this effect and, thereby, regulates its function in the COPI-vesicle cycle. Our results revise the model of ArfGAP function in the molecular context of COPI.This article has an associated First Person interview with the first author of the paper.
- MeSH
- Models, Biological * MeSH
- COP-Coated Vesicles genetics metabolism MeSH
- Coat Protein Complex I genetics metabolism MeSH
- GTPase-Activating Proteins genetics metabolism MeSH
- Saccharomyces cerevisiae Proteins genetics metabolism MeSH
- Saccharomyces cerevisiae genetics metabolism MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Cargo receptors in the endoplasmic reticulum (ER) recognize and help membrane and soluble proteins along the secretory pathway to reach their location and functional site. We characterized physiological properties of Saccharomyces cerevisiae strains lacking the ERV14 gene, which encodes a cargo receptor part of COPII-coated vesicles that cycles between the ER and Golgi membranes. The lack of Erv14 resulted in larger cell volume, plasma-membrane hyperpolarization, and intracellular pH decrease. Cells lacking ERV14 exhibited increased sensitivity to toxic cationic drugs and decreased ability to grow on low K+. We found no change in the localization of plasma membrane H+-ATPase Pma1, Na+, K+-ATPase Ena1 and K+ importer Trk2 or vacuolar K+-Cl- co-transporter Vhc1 in the absence of Erv14. However, Erv14 influenced the targeting of two K+-specific plasma-membrane transport systems, Tok1 (K+ channel) and Trk1 (K+ importer), that were retained in the ER in erv14Δ cells. The lack of Erv14 resulted in growth phenotypes related to a diminished amount of Trk1 and Tok1 proteins. We confirmed that Rb+ whole-cell uptake via Trk1 is not efficient in cells lacking Erv14. ScErv14 helped to target Trk1 homologues from other yeast species to the S. cerevisiae plasma membrane. The direct interaction between Erv14 and Tok1 or Trk1 was confirmed by co-immunoprecipitation and by a mating-based Split Ubiquitin System. In summary, our results identify Tok1 and Trk1 to be new cargoes for Erv14 and show this receptor to be an important player participating in the maintenance of several physiological parameters of yeast cells.
- MeSH
- Biological Transport physiology MeSH
- Cell Membrane metabolism MeSH
- COP-Coated Vesicles metabolism MeSH
- Gene Deletion MeSH
- Potassium metabolism MeSH
- Potassium Channels genetics metabolism MeSH
- Endoplasmic Reticulum metabolism MeSH
- Glucose metabolism MeSH
- Golgi Apparatus metabolism MeSH
- Homeostasis MeSH
- Hydrogen-Ion Concentration MeSH
- Membrane Potentials physiology MeSH
- Membrane Proteins genetics metabolism MeSH
- Cation Transport Proteins genetics metabolism MeSH
- Proton-Translocating ATPases metabolism MeSH
- Gene Expression Regulation, Fungal MeSH
- Saccharomyces cerevisiae Proteins genetics metabolism MeSH
- Saccharomyces cerevisiae genetics metabolism MeSH
- Sodium metabolism MeSH
- Sodium-Potassium-Exchanging ATPase metabolism MeSH
- Transcriptome MeSH
- Cell Size MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The export of membrane proteins along the secretory pathway is initiated at the endoplasmic reticulum after proteins are folded and packaged inside this organelle by their recruiting into the coat complex COPII vesicles. It is proposed that cargo receptors are required for the correct transport of proteins to its target membrane, however, little is known about ER export signals for cargo receptors. Erv14/Cornichon belong to a well conserved protein family in Eukaryotes, and have been proposed to function as cargo receptors for many transmembrane proteins. Amino acid sequence alignment showed the presence of a conserved acidic motif in the C-terminal in homologues from plants and yeast. Here, we demonstrate that mutation of the C-terminal acidic motif from ScErv14 or OsCNIH1, did not alter the localization of these cargo receptors, however it modified the proper targeting of the plasma membrane transporters Nha1p, Pdr12p and Qdr2p. Our results suggest that mistargeting of these plasma membrane proteins is a consequence of a weaker interaction between the cargo receptor and cargo proteins caused by the mutation of the C-terminal acidic motif.
- MeSH
- ATP-Binding Cassette Transporters genetics MeSH
- Amino Acid Motifs genetics MeSH
- Cell Membrane genetics metabolism MeSH
- COP-Coated Vesicles genetics metabolism MeSH
- Endoplasmic Reticulum genetics metabolism MeSH
- Golgi Apparatus genetics metabolism MeSH
- Membrane Proteins genetics metabolism MeSH
- Membrane Transport Proteins genetics MeSH
- Sodium-Hydrogen Exchangers genetics MeSH
- Oryza genetics MeSH
- Saccharomyces cerevisiae Proteins genetics MeSH
- Saccharomyces cerevisiae genetics MeSH
- Protein Folding MeSH
- Amino Acid Sequence genetics MeSH
- Sequence Alignment MeSH
- Protein Transport genetics MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
