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Gandhi SA, Parveen S, Alduhailan M, Tripathi R, Junedi N, Saqallah M, Sanders MA, Hoffmann PM, Truex K, Granneman JG, Kelly CV. Methods for making and observing model lipid droplets. CELL REPORTS METHODS 2024; 4:100774. [PMID: 38749444 PMCID: PMC11133809 DOI: 10.1016/j.crmeth.2024.100774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/30/2024] [Accepted: 04/19/2024] [Indexed: 05/23/2024]
Abstract
We present methods for making and testing the membrane biophysics of model lipid droplets (LDs). Methods are described for imaging LDs ranging in size from 0.1 to 40 μm in diameter with high-resolution microscopy and spectroscopy. With known LD compositions, membrane binding, sorting, diffusion, and tension were measured via fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), fluorescence lifetime imaging microscopy (FLIM), atomic force microscopy (AFM), and imaging flow cytometry. Additionally, a custom, small-volume pendant droplet tensiometer is described and used to measure the association of phospholipids to the LD surface. These complementary, cross-validating methods of measuring LD membrane behavior reveal the interplay of biophysical processes on lipid droplet monolayers.
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Affiliation(s)
- Sonali A Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Shahnaz Parveen
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Munirah Alduhailan
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Ramesh Tripathi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Nasser Junedi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Mohammad Saqallah
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Matthew A Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Peter M Hoffmann
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA; Physical Sciences Department, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, USA
| | - Katherine Truex
- Department of Physics, United States Naval Academy, Annapolis, MD 21402, USA
| | - James G Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA.
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2
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Yuan R, Liu J, Ukwatta RH, Xue F, Xiong X, Li C. Artificial oil bodies: A review on composition, properties, biotechnological applications, and improvement methods. Food Chem X 2024; 21:101109. [PMID: 38268842 PMCID: PMC10806269 DOI: 10.1016/j.fochx.2023.101109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 12/20/2023] [Accepted: 12/30/2023] [Indexed: 01/26/2024] Open
Abstract
In order to simulate the structure of natural oil body, artificial oil bodies (AOBs) are fabricated by the integration of oleosins, triacylglycerols (TAGs) and phospholipids (PLs) in vitro. Recently, AOBs have gained great research interest both in the food and biological fields due to its ability to act as a novel delivery system for bioactive compounds and as a carrier for target proteins. This review aims to summarize the composition and the preparation methods of AOBs, examine the factors influencing their stability. Moreover, this contribution focusses on exploring the application of AOBs to encapsulate functional ingredients that are prone to oxidation as well as improve efficiency involved in protein purification, renaturation and immobilization by reducing the complex steps. In addition, the improvement measures to further enhance the stability and efficacy of AOBs are also discussed. The application of AOBs is expected to be a big step towards replacing existing bioreactors and delivery systems.
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Affiliation(s)
- Ruhuan Yuan
- College of Food Science and Light Industry, Nanjing Tech University, 30 Puzhu South Road, Nanjing, 211816, PR China
| | - Jianying Liu
- College of Food Science and Light Industry, Nanjing Tech University, 30 Puzhu South Road, Nanjing, 211816, PR China
| | - Ruchika Hansanie Ukwatta
- College of Food Science and Light Industry, Nanjing Tech University, 30 Puzhu South Road, Nanjing, 211816, PR China
| | - Feng Xue
- School of Pharmacy, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, PR China
| | - Xiaohui Xiong
- College of Food Science and Light Industry, Nanjing Tech University, 30 Puzhu South Road, Nanjing, 211816, PR China
| | - Chen Li
- College of Food Science and Light Industry, Nanjing Tech University, 30 Puzhu South Road, Nanjing, 211816, PR China
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Plankensteiner L, Hennebelle M, Vincken JP, Nikiforidis CV. Insights into the emulsification mechanism of the surfactant-like protein oleosin. J Colloid Interface Sci 2024; 657:352-362. [PMID: 38043237 DOI: 10.1016/j.jcis.2023.11.165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 10/23/2023] [Accepted: 11/26/2023] [Indexed: 12/05/2023]
Abstract
Oleosins are proteins with a unique central hydrophobic hairpin designed to stabilize lipid droplets (oleosomes) in plant seeds. For efficient droplet stabilization, the hydrophobic hairpin with a strong affinity for the apolar droplet core is flanked by hydrophilic arms on each side. This gives oleosins a unique surfactant-like shape making them a very interesting protein. In this study, we tested if isolated oleosins retain their ability to stabilize oil-in-water emulsions, and investigated the underlying stabilization mechanism. Due to their surfactant-like shape, oleosins when dispersed in aqueous buffers associated to micelle-like nanoparticles with a size of ∼33 nm. These micelles, in turn, clustered into larger aggregates of up to 20 µm. Micelle aggregation was more extensive when oleosins lacked charge. During emulsification, oleosin micelles and micelle aggregates dissociated and mostly individual oleosins adsorbed on the oil droplet interface. Oleosins prevented the coalescence of the oil droplets and if sufficiently charged, droplet flocculation as well.
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Affiliation(s)
- Lorenz Plankensteiner
- Laboratory of Biobased Chemistry and Technology, Wageningen University, the Netherlands; Laboratory of Food Chemistry, Wageningen University, the Netherlands
| | - Marie Hennebelle
- Laboratory of Food Chemistry, Wageningen University, the Netherlands
| | - Jean-Paul Vincken
- Laboratory of Food Chemistry, Wageningen University, the Netherlands
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Kanduč M, Schneck E, Netz RR. Understanding the "Berg limit": the 65° contact angle as the universal adhesion threshold of biomatter. Phys Chem Chem Phys 2024; 26:713-723. [PMID: 38100091 DOI: 10.1039/d3cp05084j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Surface phenomena in aqueous environments such as long-range hydrophobic attraction, macromolecular adhesion, and even biofouling are predominantly influenced by a fundamental parameter-the water contact angle. The minimal contact angle required for these and related phenomena to occur has been repeatedly reported to be around 65° and is commonly referred to as the "Berg limit." However, the universality of this specific threshold across diverse contexts has remained puzzling. In this perspective article, we aim to rationalize the reoccurrence of this enigmatic contact angle. We show that the relevant scenarios can be effectively conceptualized as three-phase problems involving the surface of interest, water, and a generic oil-like material that is representative of the nonpolar constituents within interacting entities. Our analysis reveals that attraction and adhesion emerge when substrates display an underwater oleophilic character, corresponding to a "hydrophobicity under oil", which occurs for contact angles above approximately 65°. This streamlined view provides valuable insights into macromolecular interactions and holds implications for technological applications.
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Affiliation(s)
- Matej Kanduč
- Department of Theoretical Physics, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
| | - Emanuel Schneck
- Department of Physics, Technische Universität Darmstadt, Hochschulstrasse 8, Darmstadt 64289, Germany
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
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Zhao P, Zhao Z, Yu Z, Chen L, Jin Y, Wu J, Ren Z. Application of synthetic lipid droplets in metabolic diseases. Clin Transl Med 2023; 13:e1441. [PMID: 37997538 PMCID: PMC10668006 DOI: 10.1002/ctm2.1441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 09/16/2023] [Accepted: 10/01/2023] [Indexed: 11/25/2023] Open
Abstract
BACKGROUND The study and synthesis of membrane organelles are becoming increasingly important, not only as simplified cellular models for corresponding molecular and metabolic studies but also for applications in synthetic biology of artificial cells and drug delivery vehicles. Lipid droplets (LDs) are central organelles in cellular lipid metabolism and are involved in almost all metabolic processes. Multiple studies have also demonstrated a high correlation between LDs and metabolic diseases. During these processes, LDs reveal a highly dynamic character, with their lipid fraction, protein composition and subcellular localisation constantly changing in response to metabolic demands. However, the molecular mechanisms underlying these functions have not been fully understood due to the limitations of cell biology approaches. Fortunately, developments in synthetic biology have provided a huge breakthrough for metabolism research, and methods for in vitro synthesis of LDs have been successfully established, with great advances in protein binding, lipid function, membrane dynamics and enzymatic reactions. AIMS AND METHODS In this review, we provide a comprehensive overview of the assembly and function of endogenous LDs, from the generation of lipid molecules to how they are assembled into LDs in the endoplasmic reticulum. In particular, we highlight two major classes of synthetic LD models for fabrication techniques and their recent advances in biology and explore their roles and challenges in achieving real applications of artificial LDs in the future.
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Affiliation(s)
- Pengxiang Zhao
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
- College of Animal Science and TechnologyShandong Agricultural UniversityTaianShandongP. R. China
| | - Zichen Zhao
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
| | - Ziwei Yu
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
| | - Lupeng Chen
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
| | - Yi Jin
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
| | - Jian Wu
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
- Frontiers Science Center for Animal Breeding and Sustainable ProductionWuhanHubeiP. R. China
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal GeneticsBreeding and Reproduction of the Ministry of Education, College of Animal ScienceHuazhong Agricultural UniversityWuhanHubeiP. R. China
- Frontiers Science Center for Animal Breeding and Sustainable ProductionWuhanHubeiP. R. China
- Hubei Hongshan LaboratoryWuhanHubeiP. R. China
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Gandhi SA, Parveen S, Alduhailan M, Tripathi R, Junedi N, Saqallah M, Sanders MA, Hoffmann PM, Truex K, Granneman JG, Kelly CV. Methods for making and observing model lipid droplets. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.17.549385. [PMID: 37503132 PMCID: PMC10370146 DOI: 10.1101/2023.07.17.549385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
The mechanisms by which the lipid droplet (LD) membrane is remodeled in concert with the activation of lipolysis incorporate a complex interplay of proteins, phospholipids, and neutral lipids. Model LDs (mLDs) provide an isolated, purified system for testing the mechanisms by which the droplet composition, size, shape, and tension affects triglyceride metabolism. Described here are methods of making and testing mLDs ranging from 0.1 to 40 μm diameter with known composition. Methods are described for imaging mLDs with high-resolution microscopy during buffer exchanges for the measurement of membrane binding, diffusion, and tension via fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), fluorescence lifetime imaging microscopy (FLIM), atomic force microscopy (AFM), pendant droplet tensiometry, and imaging flow cytometry. These complementary, cross-validating methods of measuring LD membrane behavior reveal the interplay of biophysical processes in triglyceride metabolism.
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Affiliation(s)
- Sonali A. Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Shahnaz Parveen
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Munirah Alduhailan
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Ramesh Tripathi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Nasser Junedi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Mohammad Saqallah
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Matthew A. Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, USA 40201
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI USA 48201
| | - Peter M. Hoffmann
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
- Physical Sciences Department, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA 32114
| | - Katherine Truex
- Department of Physics, United States Naval Academy, Annapolis, MD, USA 21402
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, USA 40201
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI USA 48201
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI USA 48201
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Gandhi SA, Sanders MA, Granneman JG, Kelly CV. Four-color fluorescence cross-correlation spectroscopy with one laser and one camera. BIOMEDICAL OPTICS EXPRESS 2023; 14:3812-3827. [PMID: 37497523 PMCID: PMC10368031 DOI: 10.1364/boe.486937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/14/2023] [Accepted: 04/18/2023] [Indexed: 07/28/2023]
Abstract
The diffusion and reorganization of phospholipids and membrane-associated proteins are fundamental for cellular function. Fluorescence cross-correlation spectroscopy (FCCS) measures diffusion and molecular interactions at nanomolar concentration in biological systems. We have developed an economical method to simultaneously monitor diffusion and complexation with the use of super-continuum laser and spectral deconvolution from a single detector. Customizable excitation wavelengths were chosen from the wide-band source and spectral fitting of the emitted light revealed the interactions for up to four chromatically overlapping fluorophores simultaneously. This method was applied to perform four-color FCCS that we demonstrated with polystyrene nanoparticles, lipid vesicles, and membrane-bound molecules. Up to four individually customizable excitation channels were selected from the broad-spectrum fiber laser to excite the diffusers within a diffraction-limited spot. The fluorescence emission passed through a cleanup filter and a dispersive prism prior to being collected by a sCMOS or EMCCD camera with up to 1.8 kHz frame rates. The emission intensity versus time of each fluorophore was extracted through a linear least-square fitting of each camera frame and temporally correlated via custom software. Auto- and cross-correlation functions enabled the measurement of the diffusion rates and binding partners. We have measured the induced aggregation of nanobeads and lipid vesicles in solution upon increasing the buffer salinity. Because of the adaptability of investigating four fluorophores simultaneously with a cost-effective method, this technique will have wide application for examining macromolecular complex formation in model and living systems.
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Affiliation(s)
- Sonali A. Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Matthew A. Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Christopher V. Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
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Gandhi SA, Sanders MA, Granneman JG, Kelly CV. Four-color fluorescence cross-correlation spectroscopy with one laser and one camera. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.30.526256. [PMID: 36778294 PMCID: PMC9915509 DOI: 10.1101/2023.01.30.526256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The diffusion and reorganization of phospholipids and membrane-associated proteins are fundamental for cellular function. Fluorescence cross-correlation spectroscopy (FCCS) measures the diffusion and molecular interactions at nanomolar concentration in biological systems. We have developed a novel, economical method to simultaneously monitor diffusion and oligomerization with the use of super-continuum laser and spectral deconvolution from a single detector. Customizable excitation wavelengths were chosen from the wide-band source and spectral fitting of the emitted light revealed the interactions for up to four spectrally overlapping fluorophores simultaneously. This method was applied to perform four-color FCCS, as demonstrated with polystyrene nanoparticles, lipid vesicles, and membrane-bound molecules. Up to four individually customizable excitation channels were selected from the broad-spectrum fiber laser to excite the diffusers within a diffraction-limited spot. The fluorescence emission passed through a cleanup filter and a dispersive prism prior to being collected by a sCMOS or EMCCD camera with up to 10 kHz frame rates. The emission intensity versus time of each fluorophore was extracted through a linear least-square fitting of each camera frame and temporally correlated via custom software. Auto- and cross-correlation functions enabled the measurement of the diffusion rates and binding partners. We have measured the induced aggregation of nanobeads and lipid vesicles in solution upon increasing the buffer salinity. Because of the adaptability of investigating four fluorophores simultaneously with a cost-effective method, this technique will have wide application for examining complex homo- and heterooligomerization in model and living systems.
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Affiliation(s)
- Sonali A. Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA, 48201
| | - Matthew A. Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, USA, 40201
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, USA, 40201,Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI, USA. 48201
| | - Christopher V. Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA, 48201,Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI, USA. 48201,Corresponding author:
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Protocol for using artificial lipid droplets to study the binding affinity of lipid droplet-associated proteins. STAR Protoc 2022; 3:101214. [PMID: 35265861 PMCID: PMC8899027 DOI: 10.1016/j.xpro.2022.101214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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