Lipid transfer from lipoprotein particles to cells is essential for lipid homeostasis. High-density lipoprotein (HDL) particles are mainly captured by cell membrane-associated scavenger receptor class B type 1 (SR-B1) from the bloodstream, while low-density and very-low-density lipoprotein (LDL and VLDL, respectively) particles are mostly taken up by receptor-mediated endocytosis. However, the role of the target lipid membrane itself in the transfer process has been largely neglected so far. Here, we study how lipoprotein particles (HDL, LDL, and VLDL) interact with synthetic lipid bilayers and cell-derived membranes and transfer their cargo subsequently. Employing cryo-electron microscopy, spectral imaging, and fluorescence (cross) correlation spectroscopy allowed us to observe integration of all major types of lipoprotein particles into the membrane and delivery of their cargo in a receptor-independent manner. Importantly, the biophysical properties of the target cell membranes change upon delivery of cargo. The concept of receptor-independent interaction of lipoprotein particles with membranes helps us to better understand lipoprotein particle biology and can be exploited for novel treatments of dyslipidemia diseases.

• MeSH
• biologický transport MeSH
• buněčná membrána metabolismus   MeSH
• lipidové dvojvrstvy metabolismus   MeSH
• lipoproteiny metabolismus   MeSH
• mikroskopie atomárních sil MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The plant selective autophagy cargo receptor neighbour of breast cancer 1 gene (NBR1) has been scarcely studied in the context of abiotic stress. We wanted to expand this knowledge by using Arabidopsis thaliana lines with constitutive ectopic overexpression of the AtNBR1 gene (OX lines) and the AtNBR1 Knock-Out (KO lines). Transcriptomic analysis of the shoots and roots of one representative OX line indicated differences in gene expression relative to the parental (WT) line. In shoots, many differentially expressed genes, either up- or down-regulated, were involved in responses to stimuli and stress. In roots the most significant difference was observed in a set of downregulated genes that is mainly related to translation and formation of ribonucleoprotein complexes. The link between AtNBR1 overexpression and abscisic acid (ABA) signalling was suggested by an interaction network analysis of these differentially expressed genes. Most hubs of this network were associated with ABA signalling. Although transcriptomic analysis suggested enhancement of ABA responses, ABA levels were unchanged in the OX shoots. Moreover, some of the phenotypes of the OX (delayed germination, increased number of closed stomata) and the KO lines (increased number of lateral root initiation sites) indicate that AtNBR1 is essential for fine-tuning of the ABA signalling pathway. The interaction of AtNBR1 with three regulatory proteins of ABA pathway (ABI3, ABI4 and ABI5) was observed in planta. It suggests that AtNBR1 might play role in maintaining the balance of ABA signalling by controlling their level and/or activity.

• MeSH
• Arabidopsis genetika   metabolismus   MeSH
• autofagie * MeSH
• geneticky modifikované rostliny MeSH
• klíčení MeSH
• kyselina abscisová metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• semena rostlinná genetika   MeSH
• semenáček MeSH
• signální transdukce * MeSH
• transportní proteiny genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Membrane proteins are synthesized and folded in the endoplasmic reticulum (ER), and continue their path to their site of residence along the secretory pathway. The COPII system has been identified as a key player for selecting and directing the fate of membrane and secretory cargo proteins. Selection of cargo proteins within the COPII vesicles is achieved by cargo receptors. The cornichon cargo receptor belongs to a conserved protein family found in eukaryotes that has been demonstrated to participate in the selection of integral membrane proteins as cargo for their correct targeting. Here it is demonstrated at the cellular level that rice cornichon OsCNIH1 interacts with OsHKT1;3 and, in yeast cells, enables the expression of the sodium transporter to the Golgi apparatus. Physical and functional HKT-cornichon interactions are confirmed by the mating-based split ubiquitin system, bimolecular fluorescence complementation, and Xenopus oocyte and yeast expression systems. The interaction between the two proteins occurs in the ER of plant cells and their co-expression in oocytes leads to the sequestration of the transporter in the ER. In the yeast cornichon mutant erv14, OsHKT1;3 is mistargeted, preventing the toxic effects of sodium transport in the cell observed in wild-type cells or in the erv14 mutant that co-expressed OsHKT1;3 with either OsCNIH1 or Erv14p. Identification and characterization of rice cornichon as a possible cargo receptor opens up the opportunity to improve our knowledge on membrane protein targeting in plant cells.

• MeSH
• biologický transport MeSH
• endoplazmatické retikulum metabolismus   MeSH
• Golgiho aparát metabolismus   MeSH
• mapování interakce mezi proteiny MeSH
• membránové transportní proteiny genetika   metabolismus   fyziologie   MeSH
• molekulární sekvence - údaje MeSH
• proteiny přenášející kationty genetika   metabolismus   MeSH
• rostlinné proteiny genetika   metabolismus   fyziologie   MeSH
• rýže (rod) genetika   metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční analýza proteinů MeSH
• sekvenční seřazení MeSH
• sodík metabolismus   MeSH
• Xenopus MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The yeast Nha1p Na(+), K(+)/H(+) antiporter has a house-keeping role in pH and cation homeostasis. It is also needed to alleviate excess Na(+) or K(+) from the cytoplasm under high external concentrations of these cations. Erv14p, a putative cargo receptor for transmembrane proteins is required for trafficking of Nha1p from the endoplasmic reticulum to the plasma membrane. Sensitivity to high Na(+) concentrations of the erv14 mutant associated to the intracellular mislocalization of Nha1p-GFP, together with a lower Na(+) efflux, indicate the involvement of this mutual association to accomplish the survival of the yeast cell upon sodium stress. This observation is supported by the protein-protein interaction between Erv14p and Nha1p detected by the mating-based Split Ubiquitin System and co-immunoprecipitation assays. Our results indicate that even though Erv14p interacts with Nha1p through the TMD, the C-terminal is important not only for the efficient delivery of Nha1p to the plasma membrane but also for its dimerization to accomplish its role in yeast salt tolerance.

• MeSH
• biologický transport MeSH
• chlorid sodný metabolismus   farmakologie   MeSH
• draslík metabolismus   farmakologie   MeSH
• interakční proteinové domény a motivy MeSH
• kationty jednomocné MeSH
• membránové proteiny chemie   genetika   metabolismus   MeSH
• multimerizace proteinu MeSH
• Na(+)-H(+) antiport chemie   genetika   metabolismus   MeSH
• proteiny přenášející kationty chemie   genetika   metabolismus   MeSH
• protony * MeSH
• regulace genové exprese u hub * MeSH
• rekombinantní fúzní proteiny chemie   genetika   metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny chemie   genetika   metabolismus   MeSH
• Saccharomyces cerevisiae účinky léků   genetika   metabolismus   MeSH
• sekundární struktura proteinů MeSH
• tolerance k soli MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem 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
• biologický transport fyziologie   MeSH
• buněčná membrána metabolismus   MeSH
• COP-vezikuly metabolismus   MeSH
• delece genu MeSH
• draslík metabolismus   MeSH
• draslíkové kanály genetika   metabolismus   MeSH
• endoplazmatické retikulum metabolismus   MeSH
• glukosa metabolismus   MeSH
• Golgiho aparát metabolismus   MeSH
• homeostáza MeSH
• koncentrace vodíkových iontů MeSH
• membránové potenciály fyziologie   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• proteiny přenášející kationty genetika   metabolismus   MeSH
• protonové ATPasy metabolismus   MeSH
• regulace genové exprese u hub MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   MeSH
• Saccharomyces cerevisiae genetika   metabolismus   MeSH
• sodík metabolismus   MeSH
• sodíko-draslíková ATPasa metabolismus   MeSH
• transkriptom MeSH
• velikost buňky MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem 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
• antiportéry genetika   metabolismus   MeSH
• buněčná membrána metabolismus   MeSH
• COP-vezikuly genetika   metabolismus   MeSH
• endoplazmatické retikulum metabolismus   MeSH
• membránové proteiny metabolismus   fyziologie   MeSH
• proteiny přenášející kationty metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   fyziologie   MeSH
• Saccharomyces cerevisiae metabolismus   MeSH
• sodík metabolismus   MeSH
• transport proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Exosomes are small vesicles of endosomal origin that are released by almost all cell types, even those that are pathologically altered. Exosomes widely participate in cell-to-cell communication via transferring cargo, including nucleic acids, proteins, and other metabolites, into recipient cells. Tumour-derived exosomes (TDEs) participate in many important molecular pathways and affect various hallmarks of cancer, including fibroblasts activation, modification of the tumour microenvironment (TME), modulation of immune responses, angiogenesis promotion, setting the pre-metastatic niche, enhancing metastatic potential, and affecting therapy sensitivity and resistance. The unique exosome biogenesis, composition, nontoxicity, and ability to target specific tumour cells bring up their use as promising drug carriers and cancer biomarkers. In this review, we focus on the role of exosomes, with an emphasis on their protein cargo, in the key mechanisms promoting cancer progression. We also briefly summarise the mechanism of exosome biogenesis, its structure, protein composition, and potential as a signalling hub in both normal and pathological conditions. Video Abstract.

• MeSH
• exozómy * MeSH
• extracelulární vezikuly * MeSH
• lidé MeSH
• mezibuněčná komunikace MeSH
• nádorové mikroprostředí MeSH
• nádory * MeSH
• signální transdukce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• audiovizuální média MeSH
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The trafficking dynamics of uromodulin (UMOD), the most abundant protein in human urine, play a critical role in the pathogenesis of kidney disease. Monoallelic mutations in the UMOD gene cause autosomal dominant tubulointerstitial kidney disease (ADTKD-UMOD), an incurable genetic disorder that leads to kidney failure. The disease is caused by the intracellular entrapment of mutant UMOD in kidney epithelial cells, but the precise mechanisms mediating disrupted UMOD trafficking remain elusive. Here, we report that transmembrane Emp24 protein transport domain-containing (TMED) cargo receptors TMED2, TMED9, and TMED10 bind UMOD and regulate its trafficking along the secretory pathway. Pharmacological targeting of TMEDs in cells, in human kidney organoids derived from patients with ADTKD-UMOD, and in mutant-UMOD-knockin mice reduced intracellular accumulation of mutant UMOD and restored trafficking and localization of UMOD to the apical plasma membrane. In vivo, the TMED-targeted small molecule also mitigated ER stress and markers of kidney damage and fibrosis. Our work reveals TMED-targeting small molecules as a promising therapeutic strategy for kidney proteinopathies.

• MeSH
• lidé MeSH
• membránové glykoproteiny metabolismus   genetika   MeSH
• mutace MeSH
• myši MeSH
• transport proteinů * MeSH
• uromodulin * metabolismus   genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The transport of peroxisomal membrane proteins (PMPs) requires the soluble PEX19 protein as chaperone and import receptor. Recognition of cargo PMPs by the C-terminal domain (CTD) of PEX19 is required for peroxisome biogenesis in vivo. Farnesylation at a C-terminal CaaX motif in PEX19 enhances the PMP interaction, but the underlying molecular mechanisms are unknown. Here, we report the NMR-derived structure of the farnesylated human PEX19 CTD, which reveals that the farnesyl moiety is buried in an internal hydrophobic cavity. This induces substantial conformational changes that allosterically reshape the PEX19 surface to form two hydrophobic pockets for the recognition of conserved aromatic/aliphatic side chains in PMPs. Mutations of PEX19 residues that either mediate farnesyl contacts or are directly involved in PMP recognition abolish cargo binding and cannot complement a ΔPEX19 phenotype in human Zellweger patient fibroblasts. Our results demonstrate an allosteric mechanism for the modulation of protein function by farnesylation.

• MeSH
• alkyltransferasy a aryltransferasy chemie   genetika   metabolismus   MeSH
• alosterická regulace MeSH
• exprese genu MeSH
• fibroblasty metabolismus   patologie   MeSH
• hydrofobní a hydrofilní interakce MeSH
• interakční proteinové domény a motivy MeSH
• konformace proteinů, alfa-helix MeSH
• konformace proteinů, beta-řetězec MeSH
• lidé MeSH
• membránové proteiny chemie   genetika   metabolismus   MeSH
• mutace MeSH
• peroxizomy metabolismus   patologie   MeSH
• posttranslační úpravy proteinů * MeSH
• prenylace MeSH
• rekombinantní proteiny chemie   genetika   metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny chemie   genetika   metabolismus   MeSH
• Saccharomyces cerevisiae enzymologie   genetika   MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• sekvenční seřazení MeSH
• simulace molekulového dockingu MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Zellwegerův syndrom genetika   metabolismus   patologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Bardet-Biedl syndrome (BBS) is a pleiotropic ciliopathy caused by dysfunction of the BBSome, a cargo adaptor essential for export of transmembrane receptors from cilia. Although actin-dependent ectocytosis has been proposed to compensate defective cargo retrieval, its molecular basis remains unclear, especially in relation to BBS pathology. In this study, we investigated how actin polymerization and ectocytosis are regulated within the cilium. Our findings reveal that ciliary CDC42, a RHO-family GTPase triggers in situ actin polymerization, ciliary ectocytosis, and cilia shortening in BBSome-deficient cells. Activation of the Sonic Hedgehog pathway further enhances CDC42 activity specifically in BBSome-deficient cilia. Inhibition of CDC42 in BBSome-deficient cells decreases the frequency and duration of ciliary actin polymerization events, causing buildup of G protein coupled receptor 161 (GPR161) in bulges along the axoneme during Sonic Hedgehog signaling. Overall, our study identifies CDC42 as a key trigger of ciliary ectocytosis. Hyperactive ciliary CDC42 and ectocytosis and the resulting loss of ciliary material might contribute to BBS disease severity.

• MeSH
• aktiny * metabolismus   MeSH
• Bardetův-Biedlův syndrom metabolismus   genetika   patologie   MeSH
• cdc42 protein vázající GTP * metabolismus   genetika   MeSH
• cilie * metabolismus   MeSH
• lidé MeSH
• myši MeSH
• proteiny hedgehog * metabolismus   MeSH
• receptory spřažené s G-proteiny metabolismus   genetika   MeSH
• signální transdukce * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH