Trifunctional Sphingosine

Structure

(A) Native Sphingosine.

(A) Native Sphingosine.

(B) Trifunctional Sphingosine.

(B) Trifunctional Sphingosine.

Chemical structures drawn by Berit Blume.

Protein interactome

Cell background: Huh7

Authors

Scotland E. Farley, Frank Stein, Per Haberkant, Fikadu G. Tafesse, Carsten Schultz

Journal

ACS Chemical Biology

https://doi.org/10.1021/acschembio.3c00554

Abstract

Functions of the sphingolipids sphingosine and sphinganine in cells are not well established. While some signaling roles for sphingosine have been elucidated, the closely related sphinganine has been described only insofar as it does not elicit many of the same signaling responses. The underlying mechanisms behind the cell biological differences between these lipids are not well understood. Here, we prepared multifunctionalized derivatives of the two lipid species that only differ in a single double bond of the carbon backbone. Using these novel probes, we were able to define their spatiotemporal distribution within cells. Furthermore, we used these tools to systematically map the protein interactomes of both lipids. The lipid-protein conjugates, prepared through photo-crosslinking in live cells and extraction via click chemistry to azide beads, revealed significant differences in the captured proteins, highlighting their distinct roles in various cellular processes. This work elucidates mechanistic differences between these critical lipids and sets the foundation for further studies on the functions of sphingosine and sphinganine.

Lipid probes utilized

Trifunctional Sphingosine Trifunctional Sphingosine

Trifunctional Sphinganine Trifunctional Sphinganine

Cell line analyzed

Huh7

Uncaging & Crosslinking timeline

Lipid Probe Uptake time Uncaging time Interaction time Crosslinking time
Sph 60 min 5 min 15 min 5 min
Spa 60 min 5 min 15 min 5 min

Mass spectrometry quantification method

16-channel Tandem Mass Tagging (TMT16)

Additional sample preparation ?

Data as reported in Farley et al., 2024. Black proteins are unenriched or depleted in the presence of probe, Purple enriched candidates are defined as proteins with a false discovery rate less than 0.2 and a fold change of at least 1.5-fold, and Orange enriched hits are defined as proteins with a false discovery rate less than 0.05 and a fold change of at least 2-fold in the +UV over the -UV).

Data as reported in Farley et al., 2024. Black proteins are unenriched or depleted in the presence of probe, Purple enriched candidates are defined as proteins with a false discovery rate less than 0.2 and a fold change of at least 1.5-fold, and Orange enriched hits are defined as proteins with a false discovery rate less than 0.05 and a fold change of at least 2-fold in the +UV over the -UV).

Data as reported in Farley et al., 2024. Black proteins are unenriched or depleted in the presence of probe, Purple enriched candidates are defined as proteins with a false discovery rate less than 0.2 and a fold change of at least 1.5-fold, and Orange enriched hits are defined as proteins with a false discovery rate less than 0.05 and a fold change of at least 2-fold in the +UV over the -UV).

Gene Ontology Analysis

In beta: GO analysis still under development

(No MF pathways identified among enriched hits and candidates.)

(No BP pathways identified among enriched hits and candidates.)

Figure 1: GO Dot plots display the enrichment of GO terms among the proteins enriched to the probe. For these analyses, only proteins categorized as “enriched candidates” and “enriched hits” were subject to GO analysis. The Cell Compartment analysis assesses whether the list of enriched proteins contains a statistically significant number of proteins in the same cellular region; appropriately, the Molecular Function and Biological Process analyses does the same for molecular function and biological process, respectively. Click here for more information about Gene Ontology analysis.

Data exploration and download

Check the boxes below to filter by significance thresholds.


Cell background: HeLa

Authors

Doris Höglinger, André Nadler, Per Haberkant, Joanna Kirkpatrick, Martina Schifferer, Frank Stein, Sebastian Hauke, Forbes D. Porter, Carsten Schultz

Journal

PNAS

https://doi.org/10.1073/pnas.1611096114

Abstract

Lipid-mediated signaling events regulate many cellular processes. Investigations of the complex underlying mechanisms are difficult because several different methods need to be used under varying conditions. Here we introduce multifunctional lipid derivatives to study lipid metabolism, lipid−protein interactions, and intracellular lipid localization with a single tool per target lipid. The probes are equipped with two photoreactive groups to allow photoliberation (uncaging) and photo–cross-linking in a sequential manner, as well as a click-handle for subsequent functionalization. We demonstrate the versatility of the design for the signaling lipids sphingosine and diacylglycerol; uncaging of the probe for these two species triggered calcium signaling and intracellular protein translocation events, respectively. We performed proteomic screens to map the lipid-interacting proteome for both lipids. Finally, we visualized a sphingosine transport deficiency in patient-derived Niemann−Pick disease type C fibroblasts by fluorescence as well as correlative light and electron microscopy, pointing toward the diagnostic potential of such tools. We envision that this type of probe will become important for analyzing and ultimately understanding lipid signaling events in a comprehensive manner.

Lipid probes utilized

Sphingosine

Diacylglycerol

8-3 Fatty acid

Cell line analyzed

HeLa

Uncaging & Crosslinking timeline

Lipid Probe Uptake time Uncaging time Interaction time Crosslinking time
Sph 5 min 2.5 min 0 min 2.5 min
DAG 15 min 2.5 min 0 min 2.5 min
8-3 FA 15 min 2.5 min 0 min 2.5 min

Mass spectrometry quantification method

Peptide spectral counting