Publications by authors named "Casey A Ydenberg"
The patterning of actin cytoskeleton structures in vivo is a product of spatially and temporally regulated polymer assembly balanced by polymer disassembly. While in recent years our understanding of actin assembly mechanisms has grown immensely, our knowledge of actin disassembly machinery and mechanisms has remained comparatively sparse. Saccharomyces cerevisiae is an ideal system to tackle this problem, both because of its amenabilities to genetic manipulation and live-cell imaging and because only a single gene encodes each of the core disassembly factors: cofilin (COF1), Srv2/CAP (SRV2), Aip1 (AIP1), GMF (GMF1/AIM7), coronin (CRN1), and twinfilin (TWF1).
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- The study reveals how Coronin, Cofilin, and AIP1 collaboratively destabilize and disassemble filamentous actin networks through a sequential and efficient mechanism.
- Cor1B initiates the process by binding to actin filaments, which enhances the binding of Cof1, resulting in stabilized filaments.
- Cof1 then brings in AIP1, which rapidly sever the filaments and caps the new barbed ends, preventing growth, allowing for visualization of dynamic actin behavior during polymerization and disassembly.
Article Synopsis
- Asymmetric cell growth and division in budding yeast depend on the actin cytoskeleton, which is controlled by proteins, including formins.
- Hof1, a protein involved in cell division, also plays a key role in directing polarized growth by regulating the formin Bnr1, impacting the organization of actin cables and vesicle transport.
- Hof1 inhibits Bnr1's activity through specific interactions, ensuring the proper shape and function of actin cables without affecting their overall levels.
Article Synopsis
- GMF promotes the debranching of actin filament networks crucial for processes like cell movement and transport, acting similarly to the cofilin protein.
- The study identifies that GMF interacts with the Arp2/3 complex and uses two distinct binding surfaces to facilitate this debranching process.
- The mechanism of GMF's activity is conserved across different species, indicating its fundamental role in actin dynamics.
Article Synopsis
- Cell fusion is a crucial process in fertilization and is essential for forming a diploid zygote in eukaryotes, but the exact molecular mechanisms in yeast are not well understood.
- Research identifies Cdc42p, a key protein in morphogenesis, as a core component of the yeast cell fusion pathway and highlights a specific mutant version, cdc42-138, that is defective in this process.
- The study shows that Cdc42p's role in cell fusion occurs later in the fusion process and involves a specific binding with Fus2p, a regulator crucial for cell fusion, which is disrupted by the cdc42-138 mutation.
Article Synopsis
- Membrane protrusion at the front of moving cells is primarily caused by the growth of actin filaments.
- Recent advanced imaging studies sparked debate over the shape and structure of these filaments, but a consensus is starting to emerge.
- This ongoing discussion has prompted a more thorough examination of the actin networks that support cell movement and has outlined new challenges for future research.
Article Synopsis
- Yeast cells respond to mating pheromone by stopping their cell cycle in early G1, undergoing transcriptional changes, and orienting themselves towards the pheromone source.
- Fus2p, crucial for cell fusion, accumulates in the nucleus during G2/M, but is exported to the mating tip when cells arrest in G1.
- The regulation of Fus2p's export is linked to its phosphorylation by Fus3p and the activity of cyclin/Cdc28p, highlighting how yeast manage protein functions during the shift from mitosis to mating.
Article Synopsis
- Haploid yeast cells combine to create diploid zygotes, which are similar to the fertilization process in other organisms.
- Their mating process mirrors aspects of somatic cell fusion, even though it’s fundamentally sexual.
- Research on genetic mutations affecting yeast mating has revealed detailed information about cell fusion, and modern imaging and genetic techniques are enhancing our understanding of this process, shedding light on key cellular mechanisms.
Article Synopsis
- Fus2p is a protein in yeast that plays a crucial role in cell fusion during mating, showing dynamic localization in response to pheromones.
- When yeast cells respond to pheromones, Fus2p-GFP shifts from the nucleus to the cytoplasm and moves rapidly, a process reliant on Rvs161p and actin, indicating transport along actin filaments.
- At the cell junction in zygotes, Fus2p-GFP forms a ring structure and then returns to the nucleus after cell fusion is complete.