89 research outputs found
Roles for the ESCRT Machinery and the Septin Complex in Membrane Abscission During Cytokinesis
No full textAbscission occurs during the final phase of cytokinesis, effectively partitioning a mother
cell into two separate daughter cells. The process involves the scission of the
membranous intracellular bridge, resulting in the release of the midbody stmcture. Proper membrane remodeling and removal of the midbody are requirements for successful abscission, and thus the location and trafficking of the midbody can be utilized as a marker for the final steps of abscission. The septin complex and the ESCRT machinery have been linked to membrane scission and midbody removal, but their regulation and
coordination during abscission are not fully characterized. The project proposed herein
aims to utilize fluorescence microscopy-based approaches to define the interdependent and cooperative roles of the septin and ESCR T machineries during the process of abscission, using the early Caenorhabditis elegans embryo as a model system
In vivo imaging of C. elegans endocytosis
No full texta b s t r a c t Over the past decade, the early Caenorhabditis elegans embryo has proven to be a useful animal model to study a variety of membrane trafficking events, at least in part due to its large size, optical transparency, and ease of manipulation. Importantly, the stereotypic nature of membrane remodeling that occurs during early embryogenesis has enabled quantitative measurement of endocytic flux. In the absence of exogenous stimulation, resumption of the cell cycle triggered by fertilization is coupled to a dramatic redistribution of plasma membrane content. Numerous proteins are rapidly internalized via clathrinmediated endocytosis, and the fate of these cargoes can be followed precisely using live imaging in utero. Key to these studies is the maintenance of animal health and their immobilization, which can become technically challenging during extended imaging sessions. Here we highlight recent advances in live imaging techniques that have facilitated the interrogation of endocytic transport in live animals. We focus on the use of transgenic C. elegans strains that stably express fluorescently-tagged proteins, including components of the endosomal system and cargo molecules that traverse this network of membranes. Our findings demonstrate the utility of the C. elegans embryo in defining regulatory mechanisms that control the numerous steps of endocytic trafficking
Stt4 PI 4-Kinase Localizes to the Plasma Membrane and Functions in the Pkc1-Mediated MAP Kinase Cascade
No full text
Stt4 PI 4-Kinase Localizes to the Plasma Membrane and Functions in the Pkc1-Mediated MAP Kinase Cascade
No full textAbstractProduction of the essential phospholipid PI4P at the Golgi by the Pik1 kinase is required for protein secretion, while a distinct pool of PI4P generated by the Stt4 kinase is critical for normal actin cytoskeleton organization. We identify a transmembrane protein that stabilizes Stt4 at the plasma membrane where it directs synthesis of PI4P, which is required for activation of the Rho1/Pkc1-mediated MAP kinase cascade. Inactivation of Stt4 or the PI4P 5-kinase Mss4 results in mislocalization of the Rho-GTPase GEF Rom2. Rom2 binds PI4,5P2 through its PH domain and represents the first identified effector in the Stt4-Mss4 pathway. Based on these results, we propose that Stt4-Mss4 generates PI4,5P2 at the plasma membrane, required to recruit/activate effector proteins such as Rom2
- …
