Scientists have long wanted to get a closer look at the movement of lipids around a cell, but it’s tough to visualize with traditional light microscopy. UC San Diego researchers have unveiled a new technology with the power to see cells in unprecedented detail.

P116 is an adaptive, all-in-one lipid acquisition machinery fit for any host environment.

Static protein structures can capture the association of lipids, but it is unclear whether the association is due to lipids acting as long-lived ligands or the solvation of preferred lipids around the protein. A computational-experimental framework has now shown that for the protein CLC-ec1, it is the change in lipid solvation energies that drives dimerization, with preferred lipids around the protein modulating this driving force.

An approach combining bioorthogonal chemistry with genetically encoded fluorogen-activating proteins enables subcellular imaging of phospholipids and glycans, as well as the visualization of lipid tra...

Directional, non-vesicular lipid transport is responsible for fast, species-selective lipid sorting into organelle membranes.

Organelles feature characteristic lipid compositions that lead to differences in membrane properties. In cells, membrane ordering and fluidity are commonly measured using the solvatochromic dye Laurdan, whose fluorescence is sensitive to lipid packing. As a general lipophilic dye, Laurdan stains all hydrophobic environments in cells; therefore, it is challenging to characterize membrane properties in specific organelles or assess their responses to pharmacological treatments in intact cells. Here, we describe the synthesis and application of Laurdan-derived probes that read out the membrane packing of individual cellular organelles. The set of organelle-targeted Laurdans (OTL) localizes to the ER, mitochondria, lysosomes, and Golgi compartments with high specificity while retaining the spectral resolution needed to detect biological changes in membrane ordering. We show that ratiometric imaging with OTLs can resolve membrane heterogeneity within organelles as well as changes in lipid packing resulting from inhibition of trafficking or bioenergetic processes. We apply these probes to characterize organelle-specific responses to saturated lipid stress. While the ER and lysosomal membrane fluidity is sensitive to exogenous saturated fatty acids, that of mitochondrial membranes is protected. We then use differences in ER membrane fluidity to sort populations of cells based on their fatty acid diet, highlighting the ability of organelle-localized solvatochromic probes to distinguish between cells based on their metabolic state. These results expand the repertoire of targeted membrane probes and demonstrate their application in interrogating lipid dysregulation.

Depletion of a transcriptional factor ZBTB11 using molecular glue degraders can overcome oxidative-phosphorylation-mediated KRAS inhibitor resistance in pancreatic ductal adenocarcinoma with low acute...

The Shi lab at Rutgers-New Brunswick is seeking a postdoctoral researcher to study biomolecular condensates and/or mechanosensitive membrane proteins. To see more information and apply, please go to t...

Spatiotemporal control of proteins is crucial for cellular phenomena such as signal integration, propagation, as well as managing crosstalk. In membrane-associated signaling, this regulation is often enabled by lipids, wherein highly dynamic, sequential recruitment of interacting proteins is key to successful signaling. Here, we present dual SLIPT (self-localizing ligand-induced protein translocation), a lipid-analog tool, capable of emulating this lipid-mediated sequential recruitment of any two proteins of interest. Dual SLIPT self-localizes to the inner leaflet of the plasma membrane (PM). There, dual SLIPT presents trimethoprim (TMP) and HaloTag ligand (HTL) to cytosolic proteins of interest (POIs), whereupon POIs fused to the protein tags iK6eDHFR, or to HOB are recruited. A systematic extension of the linkers connecting the two mutually orthogonal headgroups was implemented to overcome the steric clash between the recruited POIs. Using Förster resonance energy transfer (FRET), we verify that the resulting probe is capable of simultaneous binding of both proteins of interest, as well as their dimerization. Dual SLIPT was found to be particularly suitable for use in physiologically relevant concentrations, such as recruitment via tightly regulated, transient lipid species. We further expanded dual SLIPT to the photocontrollable dual SLIPTNVOC, by introducing a photocaging group onto the TMP moiety. Dual SLIPTNVOC enables sequential and spatiotemporally defined dimerization upon blue light irradiation. Thus, dual SLIPTNVOC serves as a close mimic of physiology, enabling interrogation of dynamic cytosol-to-plasma membrane recruitment events and their impact on signaling.

The metabolism of ergosterol shapes this lipid to allow the formation of fluid membrane domains in yeast cells.

Summary: An examination of the morphological similarities between prokaryotic intracytoplasmic membranes and mitochondrial inner membranes, and whether cristae evolution has driven specialization of t...

This work challenges a major assumption in cell biology by showing that lipid bilayers can have drastically different phospholipid abundances between their two leaflets. This lipid abundance asymmetry...