membrane trafficking
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Formins are a large, evolutionarily old family of cytoskeletal regulators whose roles include actin capping and nucleation, as well as modulation of microtubule dynamics. The plant class I formin clade is characterized by a unique domain organization, as most of its members are transmembrane proteins with possible cell wall-binding motifs exposed to the extracytoplasmic space-a structure that appears to be a synapomorphy of the plant kingdom. While such transmembrane formins are traditionally considered mainly as plasmalemma-localized proteins contributing to the organization of the cell cortex, we review, from a cell biology perspective, the growing evidence that they can also, at least temporarily, reside (and in some cases also function) in endomembranes including secretory and endocytotic pathway compartments, the endoplasmic reticulum, the nuclear envelope, and the tonoplast. Based on this evidence, we propose that class I formins may thus serve as 'active cargoes' of membrane trafficking-membrane-embedded proteins that modulate the fate of endo- or exocytotic compartments while being transported by them.
- Klíčová slova
- Actin, biotic interactions, cell growth, cytokinesis, endocytosis, exocytosis, formin, microtubules, plasmalemma, tonoplast,
- MeSH
- buněčná membrána * metabolismus MeSH
- forminy * metabolismus MeSH
- membránové proteiny metabolismus genetika MeSH
- rostlinné proteiny metabolismus genetika MeSH
- transport proteinů * MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- forminy * MeSH
- membránové proteiny MeSH
- rostlinné proteiny MeSH
Endomembrane traffic in eukaryotic cells functions partially as a means of communication; delivery of membrane in one direction has to be balanced with a reduction at the other end. This effect is typically the case during the defence against pathogens. To combat pathogens, cellular growth and differentiation are suppressed, while endomembrane traffic is poised towards limiting the pathogen attack. The octameric exocyst vesicle-tethering complex was originally discovered as a factor facilitating vesicle-targeting and vesicle-plasma membrane (PM) fusion during exocytosis prior to and possibly during SNARE complex formation. Interestingly, it was recently implicated both in animals and plants in autophagy membrane traffic. In animal cells, the exocyst is integrated into the mTOR-regulated energy metabolism stress/starvation pathway, participating in the formation and especially initiation of an autophagosome. In plants, the first functional link was to autophagy-related anthocyanin import to the vacuole and to starvation. In this concise review, we summarize the current knowledge of exocyst functions in autophagy and defence in plants that might involve unconventional secretion and compare it with animal conditions. Formation of different exocyst complexes during undisturbed cell growth, as opposed to periods of cellular stress reactions involving autophagy, might contribute to the coordination of endomembrane trafficking pathways.
- Klíčová slova
- Autophagy, UPS, endomembranes, exocyst, plant defence, secretory transport,
- MeSH
- autofagie MeSH
- buněčná membrána metabolismus MeSH
- rostlinné proteiny metabolismus MeSH
- rostliny metabolismus MeSH
- transport proteinů MeSH
- vezikulární transportní proteiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- rostlinné proteiny MeSH
- vezikulární transportní proteiny MeSH
The plant hormone gibberellic acid (GA) is a crucial regulator of growth and development. The main paradigm of GA signaling puts forward transcriptional regulation via the degradation of DELLA transcriptional repressors. GA has also been shown to regulate tropic responses by modulation of the plasma membrane incidence of PIN auxin transporters by an unclear mechanism. Here we uncovered the cellular and molecular mechanisms by which GA redirects protein trafficking and thus regulates cell surface functionality. Photoconvertible reporters revealed that GA balances the protein traffic between the vacuole degradation route and recycling back to the cell surface. Low GA levels promote vacuolar delivery and degradation of multiple cargos, including PIN proteins, whereas high GA levels promote their recycling to the plasma membrane. This GA effect requires components of the retromer complex, such as Sorting Nexin 1 (SNX1) and its interacting, microtubule (MT)-associated protein, the Cytoplasmic Linker-Associated Protein (CLASP1). Accordingly, GA regulates the subcellular distribution of SNX1 and CLASP1, and the intact MT cytoskeleton is essential for the GA effect on trafficking. This GA cellular action occurs through DELLA proteins that regulate the MT and retromer presumably via their interaction partners Prefoldins (PFDs). Our study identified a branching of the GA signaling pathway at the level of DELLA proteins, which, in parallel to regulating transcription, also target by a nontranscriptional mechanism the retromer complex acting at the intersection of the degradation and recycling trafficking routes. By this mechanism, GA can redirect receptors and transporters to the cell surface, thus coregulating multiple processes, including PIN-dependent auxin fluxes during tropic responses.
- Klíčová slova
- DELLA, gibberellin, microtubules, polar auxin transport, vesicle trafficking,
- MeSH
- Arabidopsis růst a vývoj metabolismus MeSH
- buněčná membrána metabolismus MeSH
- gibereliny farmakologie MeSH
- kyseliny indoloctové farmakologie MeSH
- mikrotubuly metabolismus MeSH
- proteiny huseníčku genetika metabolismus MeSH
- regulace genové exprese u rostlin účinky léků MeSH
- regulátory růstu rostlin farmakologie MeSH
- signální transdukce MeSH
- transport proteinů MeSH
- třídící nexiny genetika metabolismus MeSH
- vakuoly metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- GAI protein, Arabidopsis MeSH Prohlížeč
- gibereliny MeSH
- kyseliny indoloctové MeSH
- proteiny huseníčku MeSH
- regulátory růstu rostlin MeSH
- SNX1 protein, Arabidopsis MeSH Prohlížeč
- třídící nexiny MeSH
The membrane-trafficking system is a defining facet of eukaryotic cells. The best-known organelles and major protein families of this system are largely conserved across the vast diversity of eukaryotes, implying both ancient organization and functional unity. Nonetheless, intriguing variation exists that speaks to the evolutionary forces that have shaped the endomembrane system in eukaryotes and highlights ways in which membrane trafficking in protists differs from that in our well-understood models of mammalian and yeast cells. Both parasites and free-living protists possess specialized trafficking organelles, some lineage specific, others more widely distributed - the evolution and function of these organelles begs exploration. Novel members of protein families are present across eukaryotes but have been lost in humans. These proteins may well hold clues to understanding differences in cellular function in organisms that are of pressing importance for planetary health.
The flexible development of plants is characterized by a high capacity for post-embryonic organ formation and tissue regeneration, processes, which require tightly regulated intercellular communication and coordinated tissue (re-)polarization. The phytohormone auxin, the main driver for these processes, is able to establish polarized auxin transport channels, which are characterized by the expression and polar, subcellular localization of the PIN1 auxin transport proteins. These channels are demarcating the position of future vascular strands necessary for organ formation and tissue regeneration. Major progress has been made in the last years to understand how PINs can change their polarity in different contexts and thus guide auxin flow through the plant. However, it still remains elusive how auxin mediates the establishment of auxin conducting channels and the formation of vascular tissue and which cellular processes are involved. By the means of sophisticated regeneration experiments combined with local auxin applications in Arabidopsis thaliana inflorescence stems we show that (i) PIN subcellular dynamics, (ii) PIN internalization by clathrin-mediated trafficking and (iii) an intact actin cytoskeleton required for post-endocytic trafficking are indispensable for auxin channel formation, de novo vascular formation and vascular regeneration after wounding. These observations provide novel insights into cellular mechanism of coordinated tissue polarization during auxin canalization.
- Klíčová slova
- Auxin, Auxin canalization, Cell polarity, Clathrin-mediated trafficking, Endocytic trafficking, Endocytosis, PIN1,
- MeSH
- aktiny genetika MeSH
- Arabidopsis metabolismus MeSH
- biologický transport fyziologie MeSH
- endocytóza MeSH
- klathrin metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- membránové transportní proteiny metabolismus MeSH
- polarita buněk MeSH
- proteiny huseníčku metabolismus MeSH
- regulátory růstu rostlin metabolismus MeSH
- transport proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- aktiny MeSH
- klathrin MeSH
- kyseliny indoloctové MeSH
- membránové transportní proteiny MeSH
- PIN1 protein, Arabidopsis MeSH Prohlížeč
- proteiny huseníčku MeSH
- regulátory růstu rostlin MeSH
In plants, membrane compartmentalization requires vesicle trafficking for communication among distinct organelles. Membrane proteins involved in vesicle trafficking are highly dynamic and can respond rapidly to changes in the environment and to cellular signals. Capturing their localization and dynamics is thus essential for understanding the mechanisms underlying vesicular trafficking pathways. Quantitative mass spectrometry and imaging approaches allow a system-wide dissection of the vesicular proteome, the characterization of ligand-receptor pairs and the determination of secretory, endocytic, recycling and vacuolar trafficking pathways. In this review, we highlight major proteomics and imaging methods employed to determine the location, distribution and abundance of proteins within given trafficking routes. We focus in particular on methodologies for the elucidation of vesicle protein dynamics and interactions and their connections to downstream signalling outputs. Finally, we assess their biological applications in exploring different cellular and subcellular processes.
- Klíčová slova
- Golgi, endocytosis, exocytosis, microscopy, proteomics, vesicle,
- MeSH
- biologický transport MeSH
- endocytóza MeSH
- hmotnostní spektrometrie metody MeSH
- proteom * analýza metabolismus MeSH
- proteomika * metody MeSH
- transport proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- proteom * MeSH
CFTR is a membrane protein that functions as an ion channel. Mutations that disrupt its biosynthesis, trafficking or function cause cystic fibrosis (CF). Here, we present a novel in vitro model system prepared using CRISPR/Cas9 genome editing with endogenously expressed WT-CFTR tagged with a HiBiT peptide. To enable the detection of CFTR in the plasma membrane of live cells, we inserted the HiBiT tag in the fourth extracellular loop of WT-CFTR. The 11-amino acid HiBiT tag binds with high affinity to a large inactive subunit (LgBiT), generating a reporter luciferase with bright luminescence. Nine homozygous clones with the HiBiT knock-in were identified from the 182 screened clones; two were genetically and functionally validated. In summary, this work describes the preparation and validation of a novel reporter cell line with the potential to be used as an ultimate building block for developing unique cellular CF models by CRISPR-mediated insertion of CF-causing mutations.
- MeSH
- buněčná membrána metabolismus MeSH
- buněčné linie MeSH
- CRISPR-Cas systémy genetika MeSH
- cystická fibróza * genetika metabolismus MeSH
- lidé MeSH
- protein CFTR * genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- CFTR protein, human MeSH Prohlížeč
- protein CFTR * MeSH
Diplonemids are among the most abundant and species-rich protists in the oceans. Marine heterotrophic flagellates, including diplonemids, have been suggested to play important roles in global biogeochemical cycles. Diplonemids are also the sister taxon of kinetoplastids, home to trypanosomatid parasites of global health importance, and thus are informative about the evolution of kinetoplastid biology. However, the genomic and cellular complement that underpins diplonemids' highly successful lifestyle is underexplored. At the same time, our framework describing cellular processes may not be as broadly applicable as presumed, as it is largely derived from animal and fungal model organisms, a small subset of extant eukaryotic diversity. In addition to uniquely evolved machinery in animals and fungi, there exist components with sporadic (i.e., "patchy") distributions across other eukaryotes. A most intriguing subset are components ("jötnarlogs") stochastically present in a wide range of eukaryotes but lost in animal and/or fungal models. Such components are considered exotic curiosities but may be relevant to inferences about the complexity of the last eukaryotic common ancestor (LECA) and frameworks of modern cell biology. Here, we use comparative genomics and phylogenetics to comprehensively assess the membrane-trafficking system of diplonemids. They possess several proteins thought of as kinetoplastid specific, as well as an extensive set of patchy proteins, including jötnarlogs. Diplonemids apparently function with endomembrane machinery distinct from existing cell biological models but comparable with other free-living heterotrophic protists, highlighting the importance of including such exotic components when considering different models of ancient eukaryotic genomic complexity and the cell biology of non-opisthokont organisms.
- Klíčová slova
- Euglenozoa, Jotnarlog, endosome, evolutionary cell biology, heterotroph, last eukaryotic common ancestor, membrane trafficking, phylogenetics,
- MeSH
- biologická evoluce MeSH
- fylogeneze MeSH
- Kinetoplastida * fyziologie genetika MeSH
- Publikační typ
- časopisecké články MeSH
Trafficking of proteins and lipids within the plant endomembrane system is essential to support cellular functions and is subject to rigorous regulation. Despite this seemingly strict regulation, endomembrane trafficking needs to be dynamically adjusted to ever-changing internal and environmental stimuli, while maintaining cellular integrity. Although often overlooked, the versatile second messenger Ca2+ is intimately connected to several endomembrane-associated processes. Here, we discuss the impact of electrostatic interactions between Ca2+ and anionic phospholipids on endomembrane trafficking, and illustrate the direct role of Ca2+ sensing proteins in regulating endomembrane trafficking and membrane integrity preservation. Moreover, we discuss how Ca2+ can control protein sorting within the plant endomembrane system. We thus highlight Ca2+ signaling as a versatile mechanism by which numerous signals are integrated into plant endomembrane trafficking dynamics.
- MeSH
- biologický transport MeSH
- buněčná membrána metabolismus MeSH
- fosfolipidy metabolismus MeSH
- fyziologie rostlin * MeSH
- rostlinné proteiny metabolismus MeSH
- transport proteinů MeSH
- vápníková signalizace * MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- fosfolipidy MeSH
- rostlinné proteiny MeSH
To compensate for their sessile lifestyle, plants developed several responses to exogenous changes. One of the previously investigated and not yet fully understood adaptations occurs at the level of early subcellular trafficking, which needs to be rapidly adjusted to maintain cellular homeostasis and membrane integrity under osmotic stress conditions. To form a vesicle, the membrane needs to be deformed, which is ensured by multiple factors, including the activity of specific membrane proteins, such as flippases from the family of P4-ATPases. The membrane pumps actively translocate phospholipids from the exoplasmic/luminal to the cytoplasmic membrane leaflet to generate curvature, which might be coupled with recruitment of proteins involved in vesicle formation at specific sites of the donor membrane. We show that lack of the AMINOPHOSPHOLIPID ATPASE3 (ALA3) flippase activity caused defects at the plasma membrane and trans-Golgi network, resulting in altered endocytosis and secretion, processes relying on vesicle formation and movement. The mentioned cellular defects were translated into decreased intracellular trafficking flexibility failing to adjust the root growth on osmotic stress-eliciting media. In conclusion, we show that ALA3 cooperates with ARF-GEF BIG5/BEN1 and ARF1A1C/BEX1 in a similar regulatory pathway to vesicle formation, and together they are important for plant adaptation to osmotic stress.
- Klíčová slova
- Arabidopsis thaliana, ARF, GEF, endocytosis, flippase, osmotic stress, protein trafficking, secretion,
- MeSH
- Arabidopsis * metabolismus MeSH
- biologický transport MeSH
- buněčná membrána metabolismus MeSH
- membránové proteiny metabolismus MeSH
- osmotický tlak MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- membránové proteiny MeSH
- proteiny huseníčku * MeSH
