Biology subjects

Ashton-Rickardt, I.

Publications and source records attributed to Ashton-Rickardt, I..

3 recordsLinked to original sources

bioRxiv2026

Lipid Imbalance Generates Golgi Whorls that Sequester Small GTPases

Small GTPases are generally viewed as organizers of organelle identity, with different families recruited to specific membranes by compartment-selective targeting mechanisms. Here, we identify a membrane state that reverses this relationship. Excessive peptide S-palmitoylation at Golgi generates multilamellar, filipin-poor whorls that recruit ARF, Rab, and Rho family GTPases normally associated with distinct cellular compartments. The whorls simultaneously excluded Golgi transmembrane residents, coat proteins, ER proteins, a GPI-anchored protein, and other palmitoylated proteins, demonstrating that they were selective membrane compartments rather than nonspecific protein aggregates. Preventing myristoylation of ARF6 or geranylgeranylation of Rab11a strongly reduced recruitment, whereas prenylation alone was insufficient, indicating recognition of a composite membrane-targeting code. Lowering cellular cholesterol promoted whorl formation, whereas cholesterol supplementation suppressed it. Chemically distinct lipid perturbations generated GTPase-positive Golgi whorls, suggesting convergence on a shared membrane-remodeling state. As whorls accumulated, endocytic recycling and anterograde trafficking declined, survival signaling decreased, and viability became poorly reversible. These findings show that lipid imbalance can redirect small GTPases across normal organelle boundaries, converting Golgi-derived membranes into selective sinks for trafficking regulators.

cell biology↗

bioRxiv2025

Cycling Molecular Assemblies (CyMA) for Ultrasensitive Golgi Imaging

The Golgi apparatus is central to intracellular trafficking, yet its dynamic visualization remains constrained by probes that require high concentrations and long incubations. Here we present cycling molecular assemblies (CyMA), a design concept that harnesses endogenous dynamic enzymatic futile cycle to drive ultrasensitive imaging. The BODIPY-CyMA probe operates through reversible palmitoylation-depalmitoylation mediated by palmitoyl acyltransferases and thioesterases, establishing a nonequilibrium steady-state that actively concentrates the probe at the Golgi. This enzymatic cycling converts diffusion-limited localization into self-amplifying signal generation, enabling morphology imaging at concentrations as low as 100 pM and real-time tracking of Golgi dynamics within minutes at nanomolar levels. This probe requires minimal incubation time, exhibits negligible cytotoxicity, faithfully reports pharmacological Golgi disassembly, and functions in vivo in Drosophila larvae. BODIPY-CyMA exemplifies how coupling molecular self-assembly to endogenous enzymatic cycles affords a general strategy for constructing dynamic, non-perturbative probes for live cell and in vivo imaging.

biochemistry↗

bioRxiv2025

Cycling Molecular Assemblies for Selective Cancer Cell Golgi Disruption

The Golgi apparatus is a critical organelle responsible for intracellular trafficking and signaling, orchestrating essential processes such as protein and lipid sorting1-5. Dysregulation of its function has been implicated in various pathologies, including obesity, diabetes, and cancer, highlighting its importance as a potential therapeutic target. Despite this, the development of tools to selectively target the Golgi in specific cell types remain a significant unmet challenge in imaging and drug discovery. Golgi-specific enzyme activities, such as those mediated by protein acyltransferases and thioesterases6, offer an untapped opportunity to develop subcellularly localized therapeutics. Current approaches predominantly rely on direct protein binding but lack the necessary cell selectivity7, underscoring the unmet need for innovative strategies to selectively disrupt Golgi function in cancer cells. Here, we report the development of cycling molecular assemblies (CyMA), a novel class of small peptide derivatives (e.g., dipeptides), which exploit the unique enzymatic environment of the Golgi to establish futile cycles of reversible S-acylation. These assemblies selectively accumulate in cancer cell Golgi, interfering with protein S-acylation cycles and disrupting organelle homeostasis. CyMA impair key Golgi functions, including protein trafficking, glycosylation, and secretion, while demonstrating selective sparing hepatocytes and immune cells such as M1 macrophages. This selective activity represents a paradigm shift, utilizing an enzyme switch and leveraging intracellular environment rather than direct protein binding. Unlike conventional approaches, CyMA reduce tumor growth, drug resistance, and metastasis by pleiotropically disrupting Golgi related functions. By demonstrating the potential of futile cycles as a therapeutic strategy8, this study introduces a generalizable method for targeting organelle-specific enzyme activities. These findings not only underscore the therapeutic potential of CyMA in cancer but also pave the way for future applications in other Golgi-associated diseases.

biochemistry↗