Thakral, P. | bioRxiv Science

bioRxiv2026

Orthogonal Chemical Proteomic Strategies Reveal the Cholesteryl Ester Interactome in Mammalian Cells

Cholesteryl esters (CEs) are widely regarded as inert storage forms of cholesterol, yet their potential to directly engage cellular proteins remains largely unexplored. Here, we establish an integrated chemical proteomic platform to systematically define CE-protein interactions in mammalian cells. We developed and comparatively deployed three orthogonal photoaffinity labeling strategies: (i) metabolic assembly of a bifunctional CE probe through endogenous acyl-CoA:cholesterol acyltransferase activity, (ii) direct delivery of a structurally defined diazirine-alkyne CE analog, and (iii) fragment-assisted subtraction using sterol and fatty acyl control probes to resolve interactions dependent on the intact esterified scaffold. Each probe system was rigorously validated by lipidomics and UV-dependent crosslinking prior to quantitative proteomic analysis. Integration of these complementary modalities identified 495 CE-associated proteins spanning enzymes, transporters, scaffolding proteins, and canonical sterol-binding families. The limited overlap across strategies reveals that lipid-protein engagement is strongly conditioned by biosynthetic origin, probe topology, and intracellular routing. Functional and database annotations further demonstrate enrichment of druggable and disease-linked proteins, connecting CE interactions to metabolic, neurological, and cardiovascular pathways. Collectively, this work provides the first systems-level map of CE-protein interactions and establishes a generalizable, multimodal framework for chemically resolving lipid-protein interactomes.

biochemistry↗

bioRxiv2026

Episodic and semantic memory contributions to imagination and creativity

The ability to generate novel creative ideas (divergent thinking) is closely linked with our ability to imagine novel future events (episodic simulation). Here, we employed an individual differences approach to examine whether divergent thinking and episodic simulation are differentially associated with episodic and semantic retrieval ability. In response to object word cues, participants generated meanings and definitions (semantic memory), remembered a past event (episodic memory), imagined a novel future event (episodic simulation), or generated novel uses (divergent thinking). Replicating previous findings, divergent thinking ability was predicted by the number of episodic details generated during episodic simulation. When directly comparing episodic and semantic memory, the strongest predictor of divergent thinking was semantic memory. In contrast, episodic simulation ability was predicted by both episodic and semantic memory. We interpret these findings as support for the semantic scaffold hypothesis of imagination, according to which semantic memory provides the necessary scaffold or framework for flexible expressions of cognition such as divergent thinking and episodic simulation. As episodic simulation, relative to divergent thinking, was associated with both episodic and semantic retrieval, these findings are taken to reflect common reliance on event construction processes recruited during both episodic remembering and imagining.

neuroscience↗