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Kislev N, Eidelheit S, Perlmutter S, Benayahu D. How to follow lipid droplets dynamics during adipocyte metabolism. J Cell Physiol 2022; 237:4157-4168. [PMID: 35986713 PMCID: PMC9804707 DOI: 10.1002/jcp.30857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 07/07/2022] [Accepted: 08/03/2022] [Indexed: 01/09/2023]
Abstract
Lipid droplets (LDs) are important cellular organelles due to their ability to accumulate and store lipids. LD dynamics are associated with various cellular and metabolic processes. Accurate monitoring of LD's size and shape is of prime importance as it indicates the metabolic status of the cells. Unintrusive continuous quantification techniques have a clear advantage in analyzing LDs as they measure and monitor the cells' metabolic function and droplets over time. Here, we present a novel machine-learning-based method for LDs analysis by segmentation of phase-contrast images of differentiated adipocytes (in vitro) and adipose tissue (in vivo). We developed a new workflow based on the ImageJ waikato environment for knowledge analysis segmentation plugin, which provides an accurate, label-free, live single-cell, and organelle quantification of LD-related parameters. By applying the new method on differentiating 3T3-L1 cells, the size of LDs was analyzed over time in differentiated adipocytes and their correlation with other morphological parameters. Moreover, we analyzed the LDs dynamics during catabolic changes such as lipolysis and lipophagy and demonstrated its ability to identify different cellular subpopulations based on their structural, numerical, and spatial variability. This analysis was also implemented on unstained ex vivo adipose tissues to measure adipocyte size, an important readout of the tissue's metabolism. The presented approach can be applied in different LD-related metabolic conditions to provide a better understanding of LD biogenesis and function in vivo and in vitro while serving as a new platform that enables rapid and accurate screening of data sets.
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Affiliation(s)
- Nadav Kislev
- Department of Cell and Developmental Biology, Sackler School of MedicineTel Aviv UniversityTel AvivIsrael
| | - Shira Eidelheit
- Department of Cell and Developmental Biology, Sackler School of MedicineTel Aviv UniversityTel AvivIsrael
| | - Shaked Perlmutter
- Department of Cell and Developmental Biology, Sackler School of MedicineTel Aviv UniversityTel AvivIsrael
| | - Dafna Benayahu
- Department of Cell and Developmental Biology, Sackler School of MedicineTel Aviv UniversityTel AvivIsrael
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Alshammari MA, Alshammari TK, Laezza F. Improved Methods for Fluorescence Microscopy Detection of Macromolecules at the Axon Initial Segment. Front Cell Neurosci 2016; 10:5. [PMID: 26909021 PMCID: PMC4754416 DOI: 10.3389/fncel.2016.00005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 01/11/2016] [Indexed: 11/13/2022] Open
Abstract
The axonal initial segment (AIS) is the subcellular compartment required for initiation of the action potential in neurons. Scaffolding and regulatory proteins at the AIS cluster with ion channels ensuring the integrity of electrical signaling. Interference with the configuration of this protein network can lead to profound effects on neuronal polarity, excitability, cell-to-cell connectivity and brain circuit plasticity. As such, the ability to visualize AIS components with precision provides an invaluable opportunity for parsing out key molecular determinants of neuronal function. Fluorescence-based immunolabeling is a sensitive method for morphological and molecular characterization of fine structures in neurons. Yet, even when combined with confocal microscopy, detection of AIS elements with immunofluorescence has been limited by the loss of antigenicity caused by fixative materials. This technical barrier has posed significant limitations in detecting AIS components alone or in combination with other markers. Here, we designed improved protocols targeted to confocal immunofluorescence detection of the AIS marker fibroblast growth factor 14 (FGF14) in combination with the cytoskeletal-associated protein Ankyrin-G, the scaffolding protein βIV-spectrin, voltage-gated Na+ (Nav) channels (especially the Nav1.6 isoform) and critical cell type-specific neuronal markers such as parvalbumin, calbindin, and NeuN in the mouse brain. Notably, we demonstrate that intracardiac perfusion of animals with a commercially available solution containing 1% formaldehyde and 0.5% methanol, followed by brief fixation with cold acetone is an optimal and sensitive protocol for FGF14 and other AIS marker detection that guarantees excellent tissue integrity. With variations in the procedure, we also significantly improved the detection of Nav1.6, a Nav isoform known for its fixative-sensitivity. Overall, this study provides an ensemble of immunohistochemical recipes that permit excellent staining of otherwise invisible molecules within well-preserved tissue architecture. While improving the specific investigation of AIS physiology and cell biology, our thorough study can also serve as a roadmap for optimizing immunodetection of other fixative-sensitive proteins expanding the repertoire of enabling methods for brain studies.
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Affiliation(s)
- Musaad A Alshammari
- Graduate Studies Abroad Program, King Saud UniversityRiyadh, Saudi Arabia; Department of Pharmacology and Toxicology, University of Texas Medical BranchGalveston, TX, USA
| | - Tahani K Alshammari
- Graduate Studies Abroad Program, King Saud UniversityRiyadh, Saudi Arabia; Department of Pharmacology and Toxicology, University of Texas Medical BranchGalveston, TX, USA
| | - Fernanda Laezza
- Department of Pharmacology and Toxicology, University of Texas Medical BranchGalveston, TX, USA; Mitchell Center for Neurodegenerative Diseases, University of Texas Medical BranchGalveston, TX, USA; Center for Addiction Research, University of Texas Medical BranchGalveston, TX, USA; Center for Biomedical Engineering, University of Texas Medical BranchGalveston, TX, USA
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Sanders MA, Madoux F, Mladenovic L, Zhang H, Ye X, Angrish M, Mottillo EP, Caruso JA, Halvorsen G, Roush WR, Chase P, Hodder P, Granneman JG. Endogenous and Synthetic ABHD5 Ligands Regulate ABHD5-Perilipin Interactions and Lipolysis in Fat and Muscle. Cell Metab 2015; 22:851-60. [PMID: 26411340 PMCID: PMC4862007 DOI: 10.1016/j.cmet.2015.08.023] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 06/15/2015] [Accepted: 08/27/2015] [Indexed: 12/18/2022]
Abstract
Fat and muscle lipolysis involves functional interactions of adipose triglyceride lipase (ATGL), α-β hydrolase domain-containing protein 5 (ABHD5), and tissue-specific perilipins 1 and 5 (PLIN1 and PLIN5). ABHD5 potently activates ATGL, but this lipase-promoting activity is suppressed when ABHD5 is bound to PLIN proteins on lipid droplets. In adipocytes, protein kinase A (PKA) phosphorylation of PLIN1 rapidly releases ABHD5 to activate ATGL, but mechanisms for rapid regulation of PLIN5-ABHD5 interaction in muscle are unknown. Here, we identify synthetic ligands that release ABHD5 from PLIN1 or PLIN5 without PKA activation and rapidly activate adipocyte and muscle lipolysis. Molecular imaging and affinity probe labeling demonstrated that ABHD5 is directly targeted by these synthetic ligands and additionally revealed that ABHD5-PLIN interactions are regulated by endogenous ligands, including long-chain acyl-CoA. Our results reveal a new locus of lipolysis control and suggest ABHD5 ligands might be developed into novel therapeutics that directly promote fat catabolism.
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Affiliation(s)
- Matthew A Sanders
- Center for Integrative Metabolic and Endocrine Research, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Franck Madoux
- Lead Identification Division, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Ljiljana Mladenovic
- Center for Integrative Metabolic and Endocrine Research, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Huamei Zhang
- Center for Integrative Metabolic and Endocrine Research, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Xiangqun Ye
- Center for Integrative Metabolic and Endocrine Research, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Michelle Angrish
- Center for Integrative Metabolic and Endocrine Research, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Emilio P Mottillo
- Center for Integrative Metabolic and Endocrine Research, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Joseph A Caruso
- Institute of Environmental Health Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Geoff Halvorsen
- Department of Chemistry, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - William R Roush
- Department of Chemistry, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Peter Chase
- Lead Identification Division, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Peter Hodder
- Lead Identification Division, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - James G Granneman
- Center for Integrative Metabolic and Endocrine Research, Wayne State University School of Medicine, Detroit, MI 48201, USA; John Dingell Veterans Administration Medical Center, Detroit, MI 48201, USA.
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