A molecular toolbox for interrogation of membrane contact sites

Abstract

Membrane contact sites (MCSs) are specialized subcellular compartments formed by closely apposed membranes from two organelles. The intermembrane gap is separated by a distance ranging from 10 to 35 nm. MCSs are typically maintained through dynamic protein-protein and protein-lipid interactions. These intermembrane contact sites constitute important intracellular signalling hotspots to mediate a plethora of cellular processes, including calcium homeostasis, lipid metabolism, membrane biogenesis and organelle remodelling. In recent years, a series of genetically encoded probes and chemogenetic or optogenetic actuators have been invented to aid the visualization and interrogation of MCSs in both fixed and living cells. These molecular tools have greatly accelerated the pace of mechanistic dissection of membrane contact sites at the molecular level. In this review, we present an overview on the latest progress in this endeavour, and provide a general guide to the selection of methods and molecular tools for probing interorganellar membrane contact sites.Abstract figure legend Schematic diagram showing the interorganellar membrane contact sites (MCSs), which are intimately involved in the regulation of lipid and ion exchange, organelle biogenesis and subcellular positioning. Innovative methods and genetically encoded molecular tools have been developed to aid the visualization of MCSs and non-invasive manipulation of interorganellar communication with high spatiotemporal precision.

Relevance of Membrane Contact Sites in Cancer Progression

“…MCS are defined as areas where two different organelles physically interact without merging, and therefore the identity of each of them is preserved ( Jing et al, 2020 ; Venditti et al, 2020 ). MCS are dynamic and heterogeneous structures composed of different proteins that act as a bridge between the two membranes, exerting a binding force, that might have additional functions in the cell ( Eisenberg-Bord et al, 2016 ; Peretti et al, 2020 ).…”

“…ER contact sites allow the direct exchange of macromolecules and serve as a platform for the recruitment of machinery that regulates biogenesis, division, and trafficking of organelles ( Lee et al, 2020 ). Among the broad processes taking place at such interface are Ca 2+ homeostasis, lipid signaling, and organelle remodeling ( Jing et al, 2020 ) as well as mitochondrial fusion/fission, autophagy, apoptosis, reactive oxygen species (ROS) signaling, and unfolded protein response ( van Vliet et al, 2014 ; Silva-Palacios et al, 2020 ).…”

ER-mitochondria contact sites in neurodegeneration: genetic screening approaches to investigate novel disease mechanisms

“…probes (Fig. 6a) [106]. This technique is highly specific as it uses duel recognition from primary and secondary antibodies, it can be conducted on multiple conditions as the readout is fluorescence and specialised imaging equipment is not needed [105].…”

Current and Emerging Approaches for Studying Inter-Organelle Membrane Contact Sites

“…Lattice light-sheet microscopy (LLSM) was developed by using ultrathin light sheets from two-dimensional optical lattices to reveal organelle interactome at the systems-level in COS-7, HEK293 and MEF cells (Valm et al, 2017;D'Eletto et al, 2018). Super-resolution fluorescence microscopy (SRM) offers a unique window with extreme high temporal and spatial resolution for MCSs (Sydor et al, 2015;Sezgin, 2017;Jing et al, 2019). Recently, grazing incidence structured illumination microscopy (GI-SIM), one of SRM, was developed and applied to visualize ER-mitochondria MCS in COS-7 and U2OS cells (Guo Y. et al, 2018).…”