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Zamaletdinov MF, Miettinen MS, Lipowsky R. Probing the elastic response of lipid bilayers and nanovesicles to leaflet tensions via volume per lipid. SOFT MATTER 2023; 19:6929-6944. [PMID: 37664906 DOI: 10.1039/d3sm00351e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Biological and biomimetic membranes are based on lipid bilayers, consisting of two monolayers or leaflets. One important but challenging physical parameter of these membranes is their tension. For a long time, this tension was explicitly or implicitly taken to be the bilayer tension, acting on the whole bilayer membrane. More recently, it has been realized that it is useful to decompose the bilayer tension into two leaflet tensions and that these tensions are accessible to molecular dynamics simulations. To divide the bilayer up into two leaflets, it is necessary to introduce a midsurface that defines the spatial extent of the two leaflets. In previous studies, this midsurface was obtained from the density profiles across the bilayer and was then used to compute the molecular area per lipid. Here, we develop an alternative approach based on three-dimensional Voronoi tessellation and molecular volume per lipid. Using this volume-based approach, we determine the reference states with tensionless leaflets as well as the optimal volumes and areas per lipid. The optimal lipid volumes have practically the same value in both leaflets, irrespective of the size and curvature of the nanovesicles, whereas the optimal lipid areas are different for the two leaflets and depend on the vesicle size. In addition, we introduce lateral volume compressibilities to describe the elastic response of the lipid volume to the leaflet tensions. We show that the outer leaflet of a nanovesicle is more densely packed and less compressible than the inner leaflet and that this difference becomes more pronounced for smaller vesicles.
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Affiliation(s)
- Miftakh F Zamaletdinov
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
| | - Markus S Miettinen
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
- University of Bergen, Department of Chemistry, 5007 Bergen, Norway
- Computational Biology Unit, Department of Informatics, 5008 Bergen, Norway.
| | - Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
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Lipowsky R, Ghosh R, Satarifard V, Sreekumari A, Zamaletdinov M, Różycki B, Miettinen M, Grafmüller A. Leaflet Tensions Control the Spatio-Temporal Remodeling of Lipid Bilayers and Nanovesicles. Biomolecules 2023; 13:926. [PMID: 37371505 DOI: 10.3390/biom13060926] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 05/24/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023] Open
Abstract
Biological and biomimetic membranes are based on lipid bilayers, which consist of two monolayers or leaflets. To avoid bilayer edges, which form when the hydrophobic core of such a bilayer is exposed to the surrounding aqueous solution, a single bilayer closes up into a unilamellar vesicle, thereby separating an interior from an exterior aqueous compartment. Synthetic nanovesicles with a size below 100 nanometers, traditionally called small unilamellar vesicles, have emerged as potent platforms for the delivery of drugs and vaccines. Cellular nanovesicles of a similar size are released from almost every type of living cell. The nanovesicle morphology has been studied by electron microscopy methods but these methods are limited to a single snapshot of each vesicle. Here, we review recent results of molecular dynamics simulations, by which one can monitor and elucidate the spatio-temporal remodeling of individual bilayers and nanovesicles. We emphasize the new concept of leaflet tensions, which control the bilayers' stability and instability, the transition rates of lipid flip-flops between the two leaflets, the shape transformations of nanovesicles, the engulfment and endocytosis of condensate droplets and rigid nanoparticles, as well as nanovesicle adhesion and fusion. To actually compute the leaflet tensions, one has to determine the bilayer's midsurface, which represents the average position of the interface between the two leaflets. Two particularly useful methods to determine this midsurface are based on the density profile of the hydrophobic lipid chains and on the molecular volumes.
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Affiliation(s)
- Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
| | - Rikhia Ghosh
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
- Icahn School of Medicine Mount Sinai, New York, NY 10029, USA
| | - Vahid Satarifard
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
- Yale Institute for Network Science, Yale University, New Haven, CT 06520, USA
| | - Aparna Sreekumari
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
- Department of Physics, Indian Institute of Technology Palakkad, Palakkad 678 623, India
| | - Miftakh Zamaletdinov
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
| | - Bartosz Różycki
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Markus Miettinen
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
- Department of Chemistry, University of Bergen, 5020 Bergen, Norway
| | - Andrea Grafmüller
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
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Chen S, Pounraj S, Sivakumaran N, Kakkanat A, Sam G, Kabir MT, Rehm BHA. Precision-engineering of subunit vaccine particles for prevention of infectious diseases. Front Immunol 2023; 14:1131057. [PMID: 36817419 PMCID: PMC9935699 DOI: 10.3389/fimmu.2023.1131057] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
Vaccines remain the best approach for the prevention of infectious diseases. Protein subunit vaccines are safe compared to live-attenuated whole cell vaccines but often show reduced immunogenicity. Subunit vaccines in particulate format show improved vaccine efficacy by inducing strong immune responses leading to protective immunity against the respective pathogens. Antigens with proper conformation and function are often required to induce functional immune responses. Production of such antigens requiring post-translational modifications and/or composed of multiple complex domains in bacterial hosts remains challenging. Here, we discuss strategies to overcome these limitations toward the development of particulate vaccines eliciting desired humoral and cellular immune responses. We also describe innovative concepts of assembling particulate vaccine candidates with complex antigens bearing multiple post-translational modifications. The approaches include non-covalent attachments (e.g. biotin-avidin affinity) and covalent attachments (e.g. SpyCatcher-SpyTag) to attach post-translationally modified antigens to particles.
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Affiliation(s)
- Shuxiong Chen
- Centre for Cell Factories and Biopolymers (CCFB), Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia,*Correspondence: Bernd H. A. Rehm, ; Shuxiong Chen,
| | - Saranya Pounraj
- Centre for Cell Factories and Biopolymers (CCFB), Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Nivethika Sivakumaran
- Centre for Cell Factories and Biopolymers (CCFB), Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Anjali Kakkanat
- Centre for Cell Factories and Biopolymers (CCFB), Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Gayathri Sam
- Centre for Cell Factories and Biopolymers (CCFB), Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Md. Tanvir Kabir
- Centre for Cell Factories and Biopolymers (CCFB), Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Bernd H. A. Rehm
- Centre for Cell Factories and Biopolymers (CCFB), Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia,Menzies Health Institute Queensland (MHIQ), Griffith University, Gold Coast, QLD, Australia,*Correspondence: Bernd H. A. Rehm, ; Shuxiong Chen,
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Wang J, Zhang Y, Liu C, Zha W, Dong S, Xing H, Li X. Multifunctional Lipid Nanoparticles for Protein Kinase N3 shRNA Delivery and Prostate Cancer Therapy. Mol Pharm 2022; 19:4588-4600. [PMID: 35731922 DOI: 10.1021/acs.molpharmaceut.2c00244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Protein kinase N3 (PKN3), by virtue of its abnormal expression in prostate cells, has been widely used as a target of RNAi (shRNA, siRNA, miRNA) therapy. The major challenges of PKN3 RNAi therapy lie in how to design effective interference sequences and delivery systems. Herein, new PKN3 shRNA sequences (shPKN3-2459 and shPKN3-3357) were designed, and bioreducible, biodegradable, ionizable lipid-based nanoparticles were developed for shPKN3 delivery. First, an ionizable lipid (DDA-SS-DMA) bridged with disulfide bond and ester bonds was synthesized by a three-step reaction and confirmed by MS, 1H NMR, and 13C NMR. The ionizable lipid was mixed with cholesterol, DSPC, PEG-lipid, and shPKN3 by a microfluidic mixer to prepare lipid nanoparticles (LNP-shPKN3) which were characterized by DLS and TEM. Afterward, the pH and glutathione (GSH)-responsiveness of the DDA-SS-DMA based LNP delivery system were investigated by lysosome escape and gel electrophoresis assays. Compared with the commercial transfection reagent Lipo2000, the DDA-SS-DMA based delivery system showed higher transfection efficiency and lower toxicity. Western blot analysis, invasion tests, and migration assays were performed to evaluate the silencing effect of shPKN3 in vitro. In in vivo studies, high tumor suppression (65.8%) and treatment safety were evident in the LNP-shPKN3-2459 treatment group. Taken together, the DDA-SS-DMA based delivery system encapsulating shPKN3-2459 showed significant antitumor efficacy and might be a promising formulation for the treatment of prostate cancer.
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Affiliation(s)
- Ji Wang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 214122, PR China
| | - Yanhao Zhang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 214122, PR China
| | - Chao Liu
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 214122, PR China
| | - Wenhui Zha
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 214122, PR China
| | - Shuo Dong
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 214122, PR China
| | - Hanlei Xing
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 214122, PR China
| | - Xinsong Li
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 214122, PR China
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Sreekumari A, Lipowsky R. Large stress asymmetries of lipid bilayers and nanovesicles generate lipid flip-flops and bilayer instabilities. SOFT MATTER 2022; 18:6066-6078. [PMID: 35929498 DOI: 10.1039/d2sm00618a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Much effort has been devoted to lipid bilayers and nanovesicles with a compositional asymmetry between the two leaflets of the bilayer membranes. Here, we address another fundamental asymmetry related to lipid densities and membrane tensions. To avoid membrane rupture, the osmotic conditions must be adjusted in such a way that the bilayer membranes are subject to a relatively low bilayer tension. However, even for vanishing bilayer tension, the individual leaflets can still experience significant leaflet tensions if one leaflet is stretched whereas the other leaflet is compressed. Such a stress asymmetry between the two leaflets can be directly controlled in molecular dynamics simulations by the initial assembly of the lipid bilayers. This stress asymmetry is varied here over a wide range to determine the stability and instability regimes of the asymmetric bilayers. The stability regime shrinks with decreasing size and increasing membrane curvature of the nanovesicle. In the instability regimes, the lipids undergo stress-induced flip-flops with a flip-flop rate that increases with increasing stress asymmetry. The onset of flip-flops can be characterized by a cumulative distribution function that is well-fitted by an exponential function for planar bilayers but has a sigmoidal shape for nanovesicles. In addition, the bilayer membranes form transient non-bilayer structures that relax back towards ordered bilayers with a reduced stress asymmetry. Our study reveals intrinsic limits for the possible magnitude of the transbilayer stress asymmetry and shows that the leaflet tensions represent key parameters for the flip-flop rates.
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Affiliation(s)
- Aparna Sreekumari
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany.
| | - Reinhard Lipowsky
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany.
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