RESUMEN
Multiple proteins act co-operatively in mammalian clathrin-mediated endocytosis (CME) to generate endocytic vesicles from the plasma membrane. The principles controlling the activation and organization of the actin cytoskeleton during mammalian CME are, however, not fully understood. Here, we show that the protein FCHSD2 is a major activator of actin polymerization during CME. FCHSD2 deletion leads to decreased ligand uptake caused by slowed pit maturation. FCHSD2 is recruited to endocytic pits by the scaffold protein intersectin via an unusual SH3-SH3 interaction. Here, its flat F-BAR domain binds to the planar region of the plasma membrane surrounding the developing pit forming an annulus. When bound to the membrane, FCHSD2 activates actin polymerization by a mechanism that combines oligomerization and recruitment of N-WASP to PI(4,5)P2, thus promoting pit maturation. Our data therefore describe a molecular mechanism for linking spatiotemporally the plasma membrane to a force-generating actin platform guiding endocytic vesicle maturation.
Asunto(s)
Citoesqueleto de Actina/fisiología , Proteínas Portadoras/metabolismo , Clatrina/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas Adaptadoras del Transporte Vesicular/química , Proteínas Adaptadoras del Transporte Vesicular/genética , Proteínas Adaptadoras del Transporte Vesicular/metabolismo , Proteínas Portadoras/antagonistas & inhibidores , Proteínas Portadoras/genética , Membrana Celular/química , Membrana Celular/metabolismo , Vesículas Cubiertas por Clatrina/metabolismo , Endocitosis , Células HeLa , Humanos , Liposomas/química , Liposomas/metabolismo , Proteínas de la Membrana/antagonistas & inhibidores , Proteínas de la Membrana/genética , Microscopía Fluorescente , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Proteína Neuronal del Síndrome de Wiskott-Aldrich/química , Proteína Neuronal del Síndrome de Wiskott-Aldrich/metabolismo , Dominios Homologos srcRESUMEN
Gasdermin D (GSDMD) is the common effector for cytokine secretion and pyroptosis downstream of inflammasome activation and was previously shown to form large transmembrane pores after cleavage by inflammatory caspases to generate the GSDMD N-terminal domain (GSDMD-NT)1-10. Here we report that GSDMD Cys191 is S-palmitoylated and that palmitoylation is required for pore formation. S-palmitoylation, which does not affect GSDMD cleavage, is augmented by mitochondria-generated reactive oxygen species (ROS). Cleavage-deficient GSDMD (D275A) is also palmitoylated after inflammasome stimulation or treatment with ROS activators and causes pyroptosis, although less efficiently than palmitoylated GSDMD-NT. Palmitoylated, but not unpalmitoylated, full-length GSDMD induces liposome leakage and forms a pore similar in structure to GSDMD-NT pores shown by cryogenic electron microscopy. ZDHHC5 and ZDHHC9 are the major palmitoyltransferases that mediate GSDMD palmitoylation, and their expression is upregulated by inflammasome activation and ROS. The other human gasdermins are also palmitoylated at their N termini. These data challenge the concept that cleavage is the only trigger for GSDMD activation. They suggest that reversible palmitoylation is a checkpoint for pore formation by both GSDMD-NT and intact GSDMD that functions as a general switch for the activation of this pore-forming family.
Asunto(s)
Gasderminas , Lipoilación , Proteínas de Unión a Fosfato , Especies Reactivas de Oxígeno , Animales , Femenino , Humanos , Masculino , Ratones , Aciltransferasas/metabolismo , Microscopía por Crioelectrón , Cisteína/metabolismo , Gasderminas/química , Gasderminas/metabolismo , Inflamasomas/metabolismo , Liposomas/metabolismo , Liposomas/química , Mitocondrias/metabolismo , Proteínas de Unión a Fosfato/química , Proteínas de Unión a Fosfato/metabolismo , Piroptosis , Especies Reactivas de Oxígeno/metabolismo , Células THP-1RESUMEN
OSCA/TMEM63 channels are the largest known family of mechanosensitive channels1-3, playing critical roles in plant4-7 and mammalian8,9 mechanotransduction. Here we determined 44 cryogenic electron microscopy structures of OSCA/TMEM63 channels in different environments to investigate the molecular basis of OSCA/TMEM63 channel mechanosensitivity. In nanodiscs, we mimicked increased membrane tension and observed a dilated pore with membrane access in one of the OSCA1.2 subunits. In liposomes, we captured the fully open structure of OSCA1.2 in the inside-in orientation, in which the pore shows a large lateral opening to the membrane. Unusually for ion channels, structural, functional and computational evidence supports the existence of a 'proteo-lipidic pore' in which lipids act as a wall of the ion permeation pathway. In the less tension-sensitive homologue OSCA3.1, we identified an 'interlocking' lipid tightly bound in the central cleft, keeping the channel closed. Mutation of the lipid-coordinating residues induced OSCA3.1 activation, revealing a conserved open conformation of OSCA channels. Our structures provide a global picture of the OSCA channel gating cycle, uncover the importance of bound lipids and show that each subunit can open independently. This expands both our understanding of channel-mediated mechanotransduction and channel pore formation, with important mechanistic implications for the TMEM16 and TMC protein families.
Asunto(s)
Canales de Calcio , Microscopía por Crioelectrón , Activación del Canal Iónico , Mecanotransducción Celular , Humanos , Anoctaminas/química , Anoctaminas/metabolismo , Canales de Calcio/química , Canales de Calcio/metabolismo , Canales de Calcio/ultraestructura , Lípidos/química , Liposomas/metabolismo , Liposomas/química , Modelos Moleculares , Nanoestructuras/químicaRESUMEN
AP-1 is a clathrin adaptor complex that sorts cargo between the trans-Golgi network and endosomes. AP-1 recruitment to these compartments requires Arf1-GTP. The crystal structure of the tetrameric core of AP-1 in complex with Arf1-GTP, together with biochemical analyses, shows that Arf1 activates cargo binding by unlocking AP-1. Unlocking is driven by two molecules of Arf1 that bridge two copies of AP-1 at two interaction sites. The GTP-dependent switch I and II regions of Arf1 bind to the N terminus of the ß1 subunit of one AP-1 complex, while the back side of Arf1 binds to the central part of the γ subunit trunk of a second AP-1 complex. A third Arf1 interaction site near the N terminus of the γ subunit is important for recruitment, but not activation. These observations lead to a model for the recruitment and activation of AP-1 by Arf1.
Asunto(s)
Factor 1 de Ribosilacion-ADP/química , Factor de Transcripción AP-1/química , Factor 1 de Ribosilacion-ADP/metabolismo , Regulación Alostérica , Secuencia de Aminoácidos , Animales , Cristalografía por Rayos X , Endosomas/metabolismo , Aparato de Golgi/metabolismo , Células HeLa , Humanos , Liposomas/química , Liposomas/metabolismo , Ratones , Datos de Secuencia Molecular , Alineación de Secuencia , Factor de Transcripción AP-1/metabolismoRESUMEN
Newly synthesized membrane proteins are queried by ubiquitin ligase complexes and triaged between degradative and nondegradative fates. The mechanisms that convert modest differences in substrate-ligase interactions into decisive outcomes of ubiquitination are not well understood. Here, we reconstitute membrane protein recognition and ubiquitination in liposomes using purified components from a viral-mediated degradation pathway. We find that substrate-ligase interactions in the membrane directly influence processivity of ubiquitin attachment to modulate polyubiquitination. Unexpectedly, differential processivity alone could not explain the differential fates in cultured cells of degraded and nondegraded clients. Both computational and experimental analyses identified continuous deubiquitination as a prerequisite for maximal substrate discrimination. Deubiquitinases reduce polyubiquitin dwell times preferentially on clients that dissociate more rapidly from the ligase. This explains how small differences in substrate-ligase interaction can be amplified into larger differences in net degradation. These results provide a conceptual framework for substrate discrimination during membrane protein quality control.
Asunto(s)
Endopeptidasas/metabolismo , Retículo Endoplásmico/metabolismo , Proteínas de la Membrana/metabolismo , Antígenos CD4/química , Antígenos CD4/metabolismo , Células HEK293 , Células HeLa , Proteínas del Virus de la Inmunodeficiencia Humana/metabolismo , Humanos , Liposomas/química , Liposomas/metabolismo , Proteínas de la Membrana/química , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación , Proteínas Reguladoras y Accesorias Virales/metabolismoRESUMEN
Enzymatic cleavage of transmembrane anchors to release proteins from the membrane controls diverse signaling pathways and is implicated in more than a dozen diseases. How catalysis works within the viscous, water-excluding, two-dimensional membrane is unknown. We developed an inducible reconstitution system to interrogate rhomboid proteolysis quantitatively within the membrane in real time. Remarkably, rhomboid proteases displayed no physiological affinity for substrates (K(d) ~190 µM/0.1 mol%). Instead, ~10,000-fold differences in proteolytic efficiency with substrate mutants and diverse rhomboid proteases were reflected in k(cat) values alone. Analysis of gate-open mutant and solvent isotope effects revealed that substrate gating, not hydrolysis, is rate limiting. Ultimately, a single proteolytic event within the membrane normally takes minutes. Rhomboid intramembrane proteolysis is thus a slow, kinetically controlled reaction not driven by transmembrane protein-protein affinity. These properties are unlike those of other studied proteases or membrane proteins but are strikingly reminiscent of one subset of DNA-repair enzymes, raising important mechanistic and drug-design implications.
Asunto(s)
Membrana Celular/metabolismo , Endopeptidasas/metabolismo , Escherichia coli/citología , Escherichia coli/metabolismo , Proteolisis , Secuencia de Aminoácidos , Bacterias/enzimología , Membrana Celular/química , Membrana Celular/enzimología , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/metabolismo , Endopeptidasas/química , Escherichia coli/enzimología , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Cinética , Liposomas/química , Liposomas/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Alineación de SecuenciaRESUMEN
Lipids tailor membrane identities and function as molecular hubs in all cellular processes. However, the ways in which lipids modulate protein function and structure are poorly understood and still require systematic investigation. In this Innovation article, we summarize pioneering technologies, including lipid-overlay assays, lipid pull-down assays, affinity-purification lipidomics and the liposome microarray-based assay (LiMA), that will enable protein-lipid interactions to be deciphered on a systems level. We discuss how these technologies can be applied to the charting of system-wide networks and to the development of new pharmaceutical strategies.
Asunto(s)
Membrana Celular/metabolismo , Lípidos/química , Lipoproteínas/química , Liposomas/química , Análisis por Micromatrices/métodos , Proteínas/química , Animales , Humanos , Metabolismo de los Lípidos/fisiología , Estructura Secundaria de Proteína , Estructura Terciaria de ProteínaRESUMEN
Shallow hydrophobic insertions and crescent-shaped BAR scaffolds promote membrane curvature. Here, we investigate membrane fission by shallow hydrophobic insertions quantitatively and mechanistically. We provide evidence that membrane insertion of the ENTH domain of epsin leads to liposome vesiculation, and that epsin is required for clathrin-coated vesicle budding in cells. We also show that BAR-domain scaffolds from endophilin, amphiphysin, GRAF, and ß2-centaurin limit membrane fission driven by hydrophobic insertions. A quantitative assay for vesiculation reveals an antagonistic relationship between amphipathic helices and scaffolds of N-BAR domains in fission. The extent of vesiculation by these proteins and vesicle size depend on the number and length of amphipathic helices per BAR domain, in accord with theoretical considerations. This fission mechanism gives a new framework for understanding membrane scission in the absence of mechanoenzymes such as dynamin and suggests how Arf and Sar proteins work in vesicle scission.
Asunto(s)
Membranas Intracelulares/química , Membranas Intracelulares/metabolismo , Proteínas Adaptadoras del Transporte Vesicular/química , Proteínas Adaptadoras del Transporte Vesicular/metabolismo , Animales , Línea Celular , Membrana Celular/química , Membrana Celular/metabolismo , Células HeLa , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Liposomas/química , Liposomas/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Modelos Moleculares , Estructura Terciaria de ProteínaRESUMEN
Kinesin-1 ensembles maneuver vesicular cargoes through the three-dimensional (3D) intracellular microtubule (MT) network. To define how such cargoes navigate MT intersections, we first determined how many kinesins from an ensemble on a lipid-based cargo simultaneously engage a MT, and then determined the directional outcomes (straight, turn, terminate) for liposome cargoes at perpendicular MT intersections. Run lengths of 350-nm diameter liposomes decorated with up to 20, constitutively active, truncated kinesin-1 KIF5B (K543) were longer than single motor transported cargo, suggesting multiple motor engagement. However, detachment forces of lipid-coated beads with ~20 kinesins, measured using an optical trap, showed no more than three simultaneously engaged motors, with a single engaged kinesin predominating, indicating anticooperative MT binding. At two-dimensional (2D) and 3D in vitro MT intersections, liposomes frequently paused (~2 s), suggesting kinesins simultaneously bind both MTs and engage in a tug-of-war. Liposomes showed no directional outcome bias in 2D (1.1 straight:turn ratio) but preferentially went straight (1.8 straight:turn ratio) in 3D intersections. To explain these data, we developed a mathematical model of liposome transport incorporating the known mechanochemistry of kinesins, which diffuse on the liposome surface, and have stiff tails in both compression and extension that impact how motors engage the intersecting MTs. Our model predicts the ~3 engaged motor limit observed in the optical trap and the bias toward going straight in 3D intersections. The striking similarity of these results to our previous study of liposome transport by myosin Va suggests a "universal" mechanism by which cargoes navigate 3D intersections.
Asunto(s)
Cinesinas , Liposomas , Microtúbulos , Cinesinas/metabolismo , Cinesinas/química , Liposomas/química , Liposomas/metabolismo , Microtúbulos/metabolismo , Transporte Biológico , Animales , Proteínas Motoras Moleculares/metabolismo , Proteínas Motoras Moleculares/química , Pinzas ÓpticasRESUMEN
XK-related 8 (XKR8), in complex with the transmembrane glycoprotein basigin, functions as a phospholipid scramblase activated by the caspase-mediated cleavage or phosphorylation of its C-terminal tail. It carries a putative phospholipid translocation path of multiple hydrophobic and charged residues in the transmembrane region. It also has a crucial tryptophan at the exoplasmic end of the path that regulates its scrambling activity. We herein investigated the tertiary structure of the human XKR8-basigin complex embedded in lipid nanodiscs at an overall resolution of 3.66 Å. We found that the C-terminal tail engaged in intricate polar and van der Waals interactions with a groove at the cytoplasmic surface of XKR8. These interactions maintained the inactive state of XKR8. Point mutations to disrupt these interactions strongly enhanced the scrambling activity of XKR8, suggesting that the activation of XKR8 is mediated by releasing the C-terminal tail from the cytoplasmic groove. We speculate that the cytoplasmic tail region of XKR8 functions as a plug to prevent the scrambling of phospholipids.
Asunto(s)
Proteínas Reguladoras de la Apoptosis , Basigina , Proteínas de la Membrana , Proteínas de Transferencia de Fosfolípidos , Humanos , Proteínas Reguladoras de la Apoptosis/química , Proteínas Reguladoras de la Apoptosis/genética , Basigina/química , Membrana Celular/metabolismo , Liposomas/química , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Nanopartículas/química , Proteínas de Transferencia de Fosfolípidos/química , Proteínas de Transferencia de Fosfolípidos/genética , Fosfolípidos , Conformación Proteica en Hélice alfa , Imagen Individual de MoléculaRESUMEN
Permeabilization of the outer mitochondrial membrane by pore-forming Bcl2 proteins is a crucial step for the induction of apoptosis. Despite a large set of data suggesting global conformational changes within pro-apoptotic Bak during pore formation, high-resolution structural details in a membrane environment remain sparse. Here, we used NMR and HDX-MS (Hydrogen deuterium exchange mass spectrometry) in lipid nanodiscs to gain important high-resolution structural insights into the conformational changes of Bak at the membrane that are dependent on a direct activation by BH3-only proteins. Furthermore, we determined the first high-resolution structure of the Bak transmembrane helix. Upon activation, α-helix 1 in the soluble domain of Bak dissociates from the protein and adopts an unfolded and dynamic potentially membrane-bound state. In line with this finding, comparative protein folding experiments with Bak and anti-apoptotic BclxL suggest that α-helix 1 in Bak is a metastable structural element contributing to its pro-apoptotic features. Consequently, mutagenesis experiments aimed at stabilizing α-helix 1 yielded Bak variants with delayed pore-forming activity. These insights will contribute to a better mechanistic understanding of Bak-mediated membrane permeabilization.
Asunto(s)
Liposomas/química , Lípidos de la Membrana/química , Proteínas Proto-Oncogénicas c-bcl-2/química , Proteína Destructora del Antagonista Homólogo bcl-2/química , Proteína bcl-X/química , Sitios de Unión , Clonación Molecular , Medición de Intercambio de Deuterio , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Humanos , Cinética , Liposomas/metabolismo , Lípidos de la Membrana/metabolismo , Modelos Moleculares , Resonancia Magnética Nuclear Biomolecular , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Pliegue de Proteína , Dominios y Motivos de Interacción de Proteínas , Multimerización de Proteína , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Termodinámica , Proteína Destructora del Antagonista Homólogo bcl-2/genética , Proteína Destructora del Antagonista Homólogo bcl-2/metabolismo , Proteína bcl-X/genética , Proteína bcl-X/metabolismoRESUMEN
BAK and BAX, the effectors of intrinsic apoptosis, each undergo major reconfiguration to an activated conformer that self-associates to damage mitochondria and cause cell death. However, the dynamic structural mechanisms of this reconfiguration in the presence of a membrane have yet to be fully elucidated. To explore the metamorphosis of membrane-bound BAK, we employed hydrogen-deuterium exchange mass spectrometry (HDX-MS). The HDX-MS profile of BAK on liposomes comprising mitochondrial lipids was consistent with known solution structures of inactive BAK. Following activation, HDX-MS resolved major reconfigurations in BAK. Mutagenesis guided by our HDX-MS profiling revealed that the BCL-2 homology (BH) 4 domain maintains the inactive conformation of BAK, and disrupting this domain is sufficient for constitutive BAK activation. Moreover, the entire N-terminal region preceding the BAK oligomerisation domains became disordered post-activation and remained disordered in the activated oligomer. Removal of the disordered N-terminus did not impair, but rather slightly potentiated, BAK-mediated membrane permeabilisation of liposomes and mitochondria. Together, our HDX-MS analyses reveal new insights into the dynamic nature of BAK activation on a membrane, which may provide new opportunities for therapeutic targeting.
Asunto(s)
Liposomas/química , Lípidos de la Membrana/química , Proteínas Proto-Oncogénicas c-bcl-2/química , Proteína Destructora del Antagonista Homólogo bcl-2/química , Animales , Sitios de Unión , Clonación Molecular , Medición de Intercambio de Deuterio , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Humanos , Cinética , Liposomas/metabolismo , Lípidos de la Membrana/metabolismo , Ratones , Modelos Moleculares , Resonancia Magnética Nuclear Biomolecular , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Pliegue de Proteína , Dominios y Motivos de Interacción de Proteínas , Multimerización de Proteína , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Termodinámica , Proteína Destructora del Antagonista Homólogo bcl-2/genética , Proteína Destructora del Antagonista Homólogo bcl-2/metabolismoRESUMEN
For the delivery of drugs, different nanosized drug carriers (e.g., liposomes, lipid nanoparticles, and micelles) have been developed in order to treat diseases that afflict society. Frequently, these vehicles are formed by the self-assembly of small molecules to encapsulate the therapeutic cargo of interest. Over decades, nanoparticles have been optimized to make them more efficient and specific to fulfill tailor-made tasks, such as specific cell targeting or enhanced cellular uptake. In recent years, lipid-based nanoparticles in particular have taken center stage; however, off-targeting side effects and poor endosomal escape remain major challenges since therapies require high efficacy and acceptable toxicity.To overcome these issues, many different approaches have been explored to make drug delivery more specific, resulting in reduced side effects, to achieve an optimal therapeutic effect and a lower required dose. The fate of nanoparticles is largely dependent on size, shape, and surface charge. A common approach to designing drug carriers with targeting capability is surface modification. Different approaches to functionalize nanoparticles have been investigated since the attachment of targeting moieties plays a significant role in whether they can later interact with surface-exposed receptors of cells. To this end, various strategies have been used involving different classes of biomolecules, such as small molecules, nucleic acids, antibodies, aptamers, and peptides.Peptides in particular are often used since there are many receptors overexpressed in different specific cell types. Furthermore, peptides can be produced and modified at a low cost, enabling high therapeutic screening. Cell-penetrating peptides (CPPs) and cell-targeting peptides (CTPs) are frequently used for this purpose. Less studied in this context are fusogenic coiled-coil peptides. Lipid-based nanoparticles functionalized with these peptides are able to avoid the endolysosomal pathway; instead such particles can be taken up by membrane fusion, resulting in increased delivery of payload. Furthermore, they can be used for targeting cells/organs but are not directed at surface-exposed receptors. Instead, they recognize complementary peptide sequences, facilitating their uptake into cells.In this Account, we will discuss peptides as moieties for enhanced cytosolic delivery, targeted uptake, and how they can be attached to lipid-based nanoparticles to alter their properties. We will discuss the properties imparted to the particles by peptides, surface modification approaches, and recent examples showing the power of peptides for in vitro and in vivo drug delivery. The main focus will be on the functionalization of lipid-based nanoparticles by fusogenic coiled-coil peptides, highlighting the relevance of this concept for the development of future therapeutics.
Asunto(s)
Péptidos de Penetración Celular , Nanopartículas , Liposomas/química , Sistemas de Liberación de Medicamentos , Nanopartículas/química , Portadores de Fármacos , Péptidos de Penetración Celular/química , Lípidos/químicaRESUMEN
PIEZO1 is a mechanosensitive channel that converts applied force into electrical signals. Partial molecular structures show that PIEZO1 is a bowl-shaped trimer with extended arms. Here we use cryo-electron microscopy to show that PIEZO1 adopts different degrees of curvature in lipid vesicles of different sizes. We also use high-speed atomic force microscopy to analyse the deformability of PIEZO1 under force in membranes on a mica surface, and show that PIEZO1 can be flattened reversibly into the membrane plane. By approximating the absolute force applied, we estimate a range of values for the mechanical spring constant of PIEZO1. Both methods of microscopy demonstrate that PIEZO1 can deform its shape towards a planar structure. This deformation could explain how lateral membrane tension can be converted into a conformation-dependent change in free energy to gate the PIEZO1 channel in response to mechanical perturbations.
Asunto(s)
Microscopía por Crioelectrón , Canales Iónicos/química , Canales Iónicos/ultraestructura , Microscopía de Fuerza Atómica , Silicatos de Aluminio/química , Animales , Células HEK293 , Humanos , Canales Iónicos/metabolismo , Liposomas/química , Liposomas/metabolismo , Liposomas/ultraestructura , RatonesRESUMEN
Neurite self-recognition and avoidance are fundamental properties of all nervous systems1. These processes facilitate dendritic arborization2,3, prevent formation of autapses4 and allow free interaction among non-self neurons1,2,4,5. Avoidance among self neurites is mediated by stochastic cell-surface expression of combinations of about 60 isoforms of α-, ß- and γ-clustered protocadherin that provide mammalian neurons with single-cell identities1,2,4-13. Avoidance is observed between neurons that express identical protocadherin repertoires2,5, and single-isoform differences are sufficient to prevent self-recognition10. Protocadherins form isoform-promiscuous cis dimers and isoform-specific homophilic trans dimers10,14-20. Although these interactions have previously been characterized in isolation15,17-20, structures of full-length protocadherin ectodomains have not been determined, and how these two interfaces engage in self-recognition between neuronal surfaces remains unknown. Here we determine the molecular arrangement of full-length clustered protocadherin ectodomains in single-isoform self-recognition complexes, using X-ray crystallography and cryo-electron tomography. We determine the crystal structure of the clustered protocadherin γB4 ectodomain, which reveals a zipper-like lattice that is formed by alternating cis and trans interactions. Using cryo-electron tomography, we show that clustered protocadherin γB6 ectodomains tethered to liposomes spontaneously assemble into linear arrays at membrane contact sites, in a configuration that is consistent with the assembly observed in the crystal structure. These linear assemblies pack against each other as parallel arrays to form larger two-dimensional structures between membranes. Our results suggest that the formation of ordered linear assemblies by clustered protocadherins represents the initial self-recognition step in neuronal avoidance, and thus provide support for the isoform-mismatch chain-termination model of protocadherin-mediated self-recognition, which depends on these linear chains11.
Asunto(s)
Cadherinas/metabolismo , Cadherinas/ultraestructura , Microscopía por Crioelectrón , Neuronas/química , Neuronas/metabolismo , Animales , Cadherinas/química , Cadherinas/genética , Cristalografía por Rayos X , Liposomas/química , Liposomas/metabolismo , Ratones , Modelos Moleculares , Neuronas/ultraestructura , Dominios Proteicos , Multimerización de Proteína , ProtocadherinasRESUMEN
Safe and efficacious systemic delivery of messenger RNA (mRNA) to specific organs and cells in vivo remains the major challenge in the development of mRNA-based therapeutics. Targeting of systemically administered lipid nanoparticles (LNPs) coformulated with mRNA has largely been confined to the liver and spleen. Using a library screening approach, we identified that N-series LNPs (containing an amide bond in the tail) are capable of selectively delivering mRNA to the mouse lung, in contrast to our previous discovery that O-series LNPs (containing an ester bond in the tail) that tend to deliver mRNA to the liver. We analyzed the protein corona on the liver- and lung-targeted LNPs using liquid chromatography-mass spectrometry and identified a group of unique plasma proteins specifically absorbed onto the surface that may contribute to the targetability of these LNPs. Different pulmonary cell types can also be targeted by simply tuning the headgroup structure of N-series LNPs. Importantly, we demonstrate here the success of LNP-based RNA therapy in a preclinical model of lymphangioleiomyomatosis (LAM), a destructive lung disease caused by loss-of-function mutations in the Tsc2 gene. Our lung-targeting LNP exhibited highly efficient delivery of the mouse tuberous sclerosis complex 2 (Tsc2) mRNA for the restoration of TSC2 tumor suppressor in tumor and achieved remarkable therapeutic effect in reducing tumor burden. This research establishes mRNA LNPs as a promising therapeutic intervention for the treatment of LAM.
Asunto(s)
Sistemas de Liberación de Medicamentos/métodos , Linfangioleiomiomatosis/tratamiento farmacológico , ARN Mensajero/administración & dosificación , Animales , Femenino , Técnicas de Transferencia de Gen , Ingeniería Genética/métodos , Liposomas/química , Liposomas/farmacología , Pulmón/citología , Pulmón/patología , Enfermedades Pulmonares/tratamiento farmacológico , Enfermedades Pulmonares/metabolismo , Linfangioleiomiomatosis/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Nanopartículas/química , Corona de Proteínas/química , Corona de Proteínas/metabolismo , ARN Mensajero/genética , ARN Mensajero/farmacología , ARN Interferente Pequeño/metabolismoRESUMEN
BACKGROUND: Polyethylene glycol (PEG) is a nonprotein polymer that is present in its native (unbound) form as an excipient in a range of products. It is increasingly being utilized clinically in the form of PEGylated liposomal medications and vaccines. PEG is the cause of anaphylaxis in a small percentage of drug reactions; however, diagnosis of PEG allergy is complicated by the variable and poor diagnostic performance of current skin testing protocols. OBJECTIVE: We assessed the diagnostic performance of PEGylated lipid medications as an alternative to currently described tests that use medications containing PEG excipients. METHODS: Nine patients with a strong history of PEG allergy were evaluated by skin testing with a panel of PEG-containing medications and with a PEGylated lipid nanoparticle vaccine (BNT162b2). Reactivity of basophils to unbound and liposomal PEG was assessed ex vivo, and specificity of basophil responses to PEGylated liposomes was investigated with a competitive inhibition assay. More detailed information is provided in this article's Methods section in the Online Repository available at www.jacionline.org. RESULTS: Despite compelling histories of anaphylaxis to PEG-containing medications, only 2 (22%) of 9 patients were skin test positive for purified PEG or their index reaction-indicated PEG-containing compound. Conversely, all 9 patients were skin test positive or basophil activation test positive to PEGylated liposomal BNT162b2 vaccine. Concordantly, PEGylated liposomal drugs (BNT162b2 vaccine and PEGylated liposomal doxorubicin), but not purified PEG2000, consistently induced basophil activation ex vivo in patients with PEG allergy but not in nonallergic controls. Basophil reactivity to PEGylated nanoparticles competitively inhibited by preincubation of basophils with native PEG2000. CONCLUSION: Presentation of PEG on the surface of a lipid nanoparticle increases its in vivo and ex vivo allergenicity, and improves diagnosis of PEG allergy.
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Basófilos , Hipersensibilidad a las Drogas , Liposomas , Polietilenglicoles , Pruebas Cutáneas , Humanos , Polietilenglicoles/química , Polietilenglicoles/efectos adversos , Liposomas/química , Femenino , Masculino , Hipersensibilidad a las Drogas/diagnóstico , Hipersensibilidad a las Drogas/inmunología , Persona de Mediana Edad , Adulto , Basófilos/inmunología , Anciano , Anafilaxia/inmunología , Anafilaxia/diagnóstico , Anafilaxia/inducido químicamente , Nanopartículas/químicaRESUMEN
Efforts to prolong the blood circulation time and bypass immune clearance play vital roles in improving the therapeutic efficacy of nanoparticles (NPs). Herein, a multifunctional nanoplatform (BPP@RTL) that precisely targets tumor cells is fabricated by encapsulating ultrasmall phototherapeutic agent black phosphorus quantum dot (BPQD), chemotherapeutic drug paclitaxel (PTX), and immunomodulator PolyMetformin (PM) in hybrid membrane-camouflaged liposomes. Specifically, the hybrid cell membrane coating derived from the fusion of cancer cell membrane and red blood cell membrane displays excellent tumor targeting efficiency and long blood circulation property due to the innate features of both membranes. After collaboration with aPD-L1-based immune checkpoint blockade therapy, a boosted immunotherapeutic effect is obtained due to elevated dendritic cell maturation and T cell activation. Significantly, laser-irradiated BPP@RTL combined with aPD-L1 effectively eliminates primary tumors and inhibits lung metastasis in 4T1 breast tumor model, offering a promising treatment plan to develop personalized antitumor strategy.
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Inmunoterapia , Paclitaxel , Fósforo , Puntos Cuánticos , Puntos Cuánticos/química , Puntos Cuánticos/uso terapéutico , Animales , Fósforo/química , Ratones , Paclitaxel/química , Paclitaxel/uso terapéutico , Paclitaxel/farmacología , Paclitaxel/administración & dosificación , Femenino , Humanos , Línea Celular Tumoral , Liposomas/química , Nanopartículas/química , Ratones Endogámicos BALB CRESUMEN
The size of liposomal drugs has been demonstrated to strongly correlate with their pharmacokinetics and pharmacodynamics. While the microfluidic method successfully achieves the production of liposomes with well-controlled sizes across various buffer/lipid flow rate ratio (FRR) settings, any adjustments to the FRR inevitably influence the concentration, encapsulation efficiency (EE), and stability of liposomal drugs. Here we describe a controllable cavitation-on-a-chip (CCC) strategy that facilitates the precise regulation of liposomal drug size at any desired FRR. The CCC-enabled size-specific liposomes exhibited striking differences in uptake and biodistribution behaviors, thereby demonstrating distinct antitumor efficacy in both tumor-bearing animal and melanoma patient-derived organoid (PDO) models. Intriguingly, as the liposome size decreased to approximately 80 nm, the preferential accumulation of liposomal drugs in the liver transitioned to a predominant enrichment in the kidneys. These findings underscore the considerable potential of our CCC approach in influencing the pharmacokinetics and pharmacodynamics of liposomal nanomedicines.
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Dispositivos Laboratorio en un Chip , Liposomas , Liposomas/química , Animales , Humanos , Ratones , Distribución Tisular , Tamaño de la Partícula , Antineoplásicos/farmacocinética , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/administración & dosificación , Línea Celular Tumoral , Melanoma/tratamiento farmacológico , Melanoma/patologíaRESUMEN
The integration of sonodynamic therapy (SDT) with cuproptosis for targeted cancer treatment epitomizes a significant advancement in oncology. Herein, we present a dual-responsive therapeutic system, "CytoNano", which combines a cationic liposome infused with copper-nitride nanoparticles and oxygen-rich perfluorocarbon (Lip@Cu3N/PFC-O2), all enveloped in a biomimetic coating of neutrophil membrane and acid-responsive carboxymethylcellulose. CytoNano leverages the cellular mimicry of neutrophils and acid-responsive materials, enabling precise targeting of tumors and their acidic microenvironment. This strategic design facilitates the targeted release of Lip@Cu3N/PFC-O2 within the tumor, enhancing cancer cell uptake and mitochondrial localization. Consequently, it amplifies the therapeutic efficacy of both Cu3N-driven SDT and cuproptosis while preserving healthy tissues. Additionally, CytoNano's ultrasound responsiveness enhances intratumoral oxygenation, overcoming physiological barriers and initiating a combined sonodynamic-cuproptotic effect that induces multiple cell death pathways. Thus, we pioneer a biomimetic approach in precise sonodynamic cuproptosis, revolutionizing cancer therapy.