bims-mecosi 2023-01-22 papers

Issue of 2023–01–22
four papers selected by
Verena Kohler, University of Graz

New Phytol. 2023 Jan 18.

Keep in contact: multiple roles of endoplasmic reticulum-membrane contact sites and the organelle interaction network in plants.

Pengwei Wang, Patrick Duckney, Erlin Gao, Patrick J Hussey, Verena Kriechbaumer, Chengyang Li, Jingze Zang, Tong Zhang.

Functional regulation and structural maintenance of the different organelles in plants contribute directly to plant development, reproduction and stress responses. To ensure these activities take place effectively, cells have evolved an inter-connected network amongst various subcellular compartments, regulating rapid signal transduction and the exchange of biomaterial. Many proteins that regulate membrane connections have recently been identified in plants and this is the first step in elucidating both the mechanism and function of these connections. Amongst all organelles, the endoplasmic reticulum is the key structure which likely links most of the different subcellular compartments through membrane contact sites (MCS) and the ER-PM contact sites (EPCS) have been the most intensely studied in plants. However, the molecular composition and function of plant MCS are being found to be different from other eukaryotic systems. In this article, we will summarize the most recent advances in this field, and discuss the mechanism and biological relevance of these essential links in plants.

Keywords: Autophagy; Cytoskeleton; Endoplasmic reticulum; Membrane contact sites; Membrane trafficking; Mitochondria; Organelle interactions

DOI: https://doi.org/10.1111/nph.18745

Biol Chem. 2023 Jan 20.

The role of lysosomes in lipid homeostasis.

Florian Fröhlich, Ayelén González Montoro.

Lipids function as the major building blocks of cellular membranes, as signaling molecules and as energy stores for metabolism. These important functions require a precise regulation of lipid biosynthesis, transport, turnover and storage. Lipids are exchanged among organelles through a sophisticated network of vesicular and non-vesicular transport routes. Lysosomes, as the main catabolic organelle, are at the center of this network and have recently evolved as one of the master-regulators of cellular lipid metabolism. Lipids from both endogenous and exogenous sources can be processed, sensed and sorted in and out of the lysosome. In this review, we focus on the role of the lysosome in lipid catabolism, transport and signaling. We highlight recent discoveries on the transport of lipids out of the lysosomal lumen and their exchange with other organelles via membrane contact sites. We also discuss the direct role of lysosomal lipids in the TORC1 signaling pathway, a regulator of cellular metabolism. Finally, we address lysosomal biogenesis, its role in the sorting of lipid metabolic enzymes and the dysregulation of these processes in disease.

Keywords: TORC1; contact sites; lipids; lysosome; sphingolipids; vacuole

DOI: https://doi.org/10.1515/hsz-2022-0287

Methods Mol Biol. 2023 ;2608 225-246

Invadopodia Methods: Detection of Invadopodia Formation and Activity in Cancer Cells Using Reconstituted 2D and 3D Collagen-Based Matrices.

David Remy, Anne-Sophie Macé, Philippe Chavrier, Pedro Monteiro.

Tumor dissemination involves cancer cell migration through the extracellular matrix (ECM). ECM is mainly composed of collagen fibers that oppose cell invasion. To overcome hindrance in the matrix, cancer cells deploy a protease-dependent program in order to remodel the matrix fibers. Matrix remodeling requires the formation of actin-based matrix/plasma membrane contact sites called invadopodia, responsible for collagen cleavage through the accumulation and activity of the transmembrane type-I matrix metalloproteinase (MT1-MMP). In this article, we describe experimental procedures designed to assay for invadopodia formation and for invadopodia activity using 2D and 3D models based on gelatin (denatured collagen) and fibrillar type-I collagen matrices.

Keywords: Collagen; Confocal spinning disk microscopy; Gelatin; Indirect immunofluorescence; Invadopodia; Matrix degradation

DOI: https://doi.org/10.1007/978-1-0716-2887-4_14

Nat Methods. 2023 Jan 16.

Integrated multimodality microscope for accurate and efficient target-guided cryo-lamellae preparation.

Weixing Li, Jing Lu, Ke Xiao, Maoge Zhou, Yuanyuan Li, Xiang Zhang, Zhixun Li, Lusheng Gu, Xiaojun Xu, Qiang Guo, Tao Xu, Wei Ji.

Cryo-electron tomography (cryo-ET) is a revolutionary technique for resolving the structure of subcellular organelles and macromolecular complexes in their cellular context. However, the application of the cryo-ET is hampered by the sample preparation step. Performing cryo-focused ion beam milling at an arbitrary position on the sample is inefficient, and the target of interest is not guaranteed to be preserved when thinning the cell from several micrometers to less than 300 nm thick. Here, we report a cryogenic correlated light, ion and electron microscopy (cryo-CLIEM) technique that is capable of preparing cryo-lamellae under the guidance of three-dimensional confocal imaging. Moreover, we demonstrate a workflow to preselect and preserve nanoscale target regions inside the finished cryo-lamellae. By successfully preparing cryo-lamellae that contain a single centriole or contact sites between subcellular organelles, we show that this approach is generally applicable, and shall help in innovating more applications of cryo-ET.

DOI: https://doi.org/10.1038/s41592-022-01749-z