Cell Signal. 2026 Nov 12. pii: S0898-6568(26)00669-8. [Epub ahead of print]
113009
The mechanistic target of rapamycin (mTOR) coordinates cell growth, metabolism, protein synthesis, autophagy, and survival by integrating nutrient availability, growth factors, energy status, mechanical cues, and cellular stress. Beyond classical biochemical cascades, mTOR signaling specificity is fundamentally governed by subcellular localization, temporal recruitment, and microenvironmental context. This review synthesizes current insights into the spatial architecture of mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) across lysosomes, endosomes, plasma-membrane microdomains, organelle contact sites, neuronal processes, the nucleus, and biomolecular condensates. We examine how physical principles-including membrane composition and curvature, molecular confinement, macromolecular crowding, scaffold-mediated multivalent interactions, organelle positioning, mechanical tension, and localized translation-dictate signaling outcomes. Furthermore, we contrast membrane-anchored molecular assemblies with three-dimensional biomolecular condensates, detailing their interplay during stress adaptation. Spatial constraints in specialized cell geometries, such as neuronal compartments and developing tissues, illustrate how identical signaling machinery yields divergent functional outputs under altered diffusion environments. We also evaluate how advances in spatial multi-omics and super-resolution imaging extend these subcellular paradigms to tissue-scale heterogeneity. Finally, we highlight major translational hurdles, including the trade-off between spatial resolution and dynamic temporal tracking in current technologies, as well as the inability of conventional pharmacotherapies to selectively target discrete subcellular mTOR pools. Establishing spatial organization as a primary determinant of mTOR signaling clarifies context-dependent physiological outputs and provides a roadmap for developing next-generation spatially targeted therapeutics.
Keywords: Biomolecular condensates; Localized translation; Mechanistic target of rapamycin (mTOR); Membrane microdomains; Metabolic signaling; Spatial regulation; Subcellular compartmentalization