bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.03.28.587130

Arp2/3-dependent actin assembly shapes endosomes and promotes intracellular trafficking in fission yeast

Melero, A.·Muriel-Lopez, O.·Basante-Bedoya, M.·Martin, S. G.
View original source ↗Export metadata ↓

Abstract

Endosomes serve as crucial sorting centres that streamline the distribution of cell surface proteins. The early endosome receives traffic from both the plasma membrane (PM) and the Golgi, and orchestrates the redistribution of cargoes for recycling to the PM or through retrograde movement to the Golgi, and for degradation to late endosomes and lysosomes 1. In animal cells and amoebae, Arp2/3-mediated F-actin assembly plays critical roles in many aspects of endosome function, from capturing cargo to generating the forces required for membrane deformation and creating cargo-enriched transport carriers, thus promoting both recycling and degradative trafficking routes 2. Yeast models, which allowed dissection of the major membrane trafficking routes 3, exhibit highly simplified endosomes, as shown in Saccharomyces cerevisiae, where the trans-Golgi network (TGN) functions as recycling endosome 4. Furthermore, there is no reported role for Arp2/3 or F-actin in endomembrane remodelling; in fact, the Arp2/3 activators on animal endosomes - the WASH complex promoting recycling of transmembrane receptors towards the PM or TGN 5,6, and Annexin A2 necessary for endosome maturation and the movement of cargoes towards the degradative pathway 7 - do not exist in yeast cells 8,9. Here, we report that Arp2/3 and F-actin are present on fission yeast endosomes. Through live-imaging and correlative light-electron tomography, we demonstrate that Arp2/3 activity controls endosomal morphology and that this activity is essential for trafficking from the endosome to the degradative vacuole. Thus, Arp2/3-dependent actin assembly has a deeply conserved role in shaping and promoting the function of the endomembrane trafficking system.

Source connections

Explore related subjects

cell biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Melero, A., Muriel-Lopez, O., Basante-Bedoya, M., Martin, S. G.. 2024-03-29. Arp2/3-dependent actin assembly shapes endosomes and promotes intracellular trafficking in fission yeast. https://doi.org/10.1101/2024.03.28.587130

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Differential requirement for the Ire1 luminal domain in Candida albicans drug susceptibility and pathogenicity

The opportunistic human pathogen Candida albicans depends on the unfolded protein response (UPR) for cell wall integrity, antifungal tolerance, filamentous growth, and virulence. The UPR is driven by the conserved transmembrane sensor Ire1, which is activated either by misfolded proteins through its luminal domain or by lipid bilayer stress (LBS) through its transmembrane domain. In budding yeast, these two activation modes deploy divergent transcriptional programs. Whether the requirement for these two input domains is separable in C. albicans, where the cell membrane and cell wall are themselves the targets of major antifungal drug classes, remains unknown. Here, we engineered a C. albicans strain expressing Ire1 lacking an intact luminal domain (ire1{Delta}LD), which no longer detects proteotoxic stress. The ire1{Delta}LD strain grew in the presence of the azole antifungals fluconazole and miconazole but was highly sensitive to heat shock, cell wall stress, and the echinocandin caspofungin. It was also unable to sustain filamentous growth and showed reduced virulence in a Caenorhabditis elegans infection model. RNA sequencing revealed only modest changes to the steady-state transcriptome of ire1{Delta}LD cells. Together, these findings define a differential requirement for the input domains of C. albicans Ire1, uncoupling growth under azole-induced membrane stress from the cell wall, thermal, and virulence-associated outputs that depend on proteotoxic sensing, a distinction that could inform antifungal strategies targeting the UPR.

cell biology↗
bioRxiv2026

Nucleosome Core Allostery Governs Chromatin Recognition and Cell Fate

Nucleosomes regulate chromatin folding, accessibility, and factor recruitment. Current models primarily attribute these functions to histone tail modifications, while the core is largely viewed as a structural scaffold. Yet subtle changes within the nucleosome core can produce profound functional consequences, and the mechanisms underlying these effects remain unclear. Here, we describe nucleosome core allostery as a fundamental principle of chromatin regulation that amplifies the impact of minimal nucleosome variations. Leveraging natural differences between H2A.Z variants, we show that the nucleosome core encodes distinct conformational dynamics that propagate allosterically, thereby controlling nucleosome accessibility and recognition by chromatin factors. As a result, a single buried amino acid substitution alone is sufficient to reprogram nucleosome dynamics and bias cell identity. Our findings establish the nucleosome core as an allosteric regulatory module and provide a generalizable framework for how subtle variation within nucleosomes is amplified into diverse biological outcomes in development and disease.

cell biology↗
bioRxiv2026

YAP/TAZ-controlled ERK dynamics coordinate progenitor expansion and differentiation commitment

Progenitor cells must proliferate to expand the cell population, yet terminal differentiation requires this proliferative state to end. How signaling controls the duration of this proliferative window remains poorly understood. Using adipogenesis and live single-cell imaging of differentiation, cell-cycle, and ERK-activity reporters, we show that YAP and TAZ coordinate progenitor expansion with differentiation commitment by regulating ERK dynamics. YAP/TAZ maintain cells in a fluctuating high-ERK state that promotes proliferation while actively keeping the differentiation driver PPARG below the threshold for irreversible commitment. Crucially, this differentiation block is not explained by proliferation alone: inhibiting CDK4/6 or AKT suppressed proliferation without restoring differentiation, whereas MEK-ERK inhibition restored differentiation even when YAP/TAZ activity remained high. As YAP/TAZ activity decreases, dampened ERK fluctuations trigger PPARG activation. These findings support a self-limiting model in which YAP/TAZ-driven progenitor expansion progressively increases cell density and contact-dependent Hippo signaling, reducing YAP/TAZ activity and terminating the proliferative phase. Consequently, transient YAP/TAZ activation expands the progenitor pool while preserving subsequent differentiation, whereas sustained activation suppresses commitment. Together, these findings identify YAP/TAZ-controlled ERK dynamics as the nexus coordinating progenitor expansion with terminal differentiation and suggest that slower density-dependent Hippo feedback may set the duration of this proliferative window to regulate differentiated cell-number output.

cell biology↗