Abstract
Lipid droplets (LDs) are the major lipid storage organelles of eukaryotic cells and together with mitochondria key regulators of cell bioenergetics. LDs communicate with mitochondria and other organelles forming "metabolic synapse" contacts to ensure that lipid supply occurs where and when necessary. Although transmission electron microscopyanalysis allows an accurate and precise analysis of contacts, the characterization ofa large number ofcells and conditions can become a long-term process.In order to extend contact analysis tohundredsof cellsand multiple conditions,we have combinedconfocalfluorescence microscopy with advanced image analysis methods.In this work, wehave developed the ImageJ macro script ContactJ, a novel and straight image analysis method to identify and quantify contacts between LD and mitochondria in fluorescence microscopy images allowing the automatic analysis. This image analysis workflow combines colocalization and skeletonization methods, enabling the quantification of LD-mitochondria contacts together with a complete characterization of organelles and cellular parameters. The correlation and normalization of these parameters contribute to the complex description of cell behavior under differentexperimentalenergetic states. ContactJ is available here: https://doi.org/10.5281/zenodo.5810874.
Highlights
Lipid droplets (LDs) are the major lipid storage organelles of eukaryotic cells and together with mitochondria key regulators of cell’s bioenergetics
In order to achieve their functions, LDs communicate with mitochondria and other organelles forming membrane contact sites,2 “metabolic synapses”, to ensure that lipid provision occurs where and when necessary.[1,3,4]. Contact sites between these organelles have been described and characterized by transmission electron microscopy (TEM) as it resolves at the membrane scale where these contacts take place.[2,5]
We describe a novel and straight image analysis method (ContactJ) to identify and quantify contact regions between LD and mitochondria in fluorescence microscopy images allowing the automatic analysis of hundreds of cells and multiple conditions
Summary
Keywords Contact sites, Lipid Droplets, Mitochondria, Image Processing and Analysis, ImageJ, Fluorescence Microscopy, Bioimaging, Interactome article can be found at the end of the article. This article is included in the NEUBIAS - the Bioimage Analysts Network gateway. This article is included in the Cell & Molecular Biology gateway. This article has improved by including the following developments: Any further responses from the reviewers can be found at the end of the article
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