Plasma membrane furrow formation is crucial in cell division and cytokinesis. Furrow formation in early syncytial Drosophila embryos is exceptionally rapid, with furrows forming in as little as 3.75 min. Here, we use 4D imaging to identify furrow formation, stabilization, and regression periods, and identify a rapid, membrane-dependent pathway that is essential for plasma membrane furrow formation in vivo. Myosin II function is thought to provide the ingression force for cytokinetic furrows, but the role of membrane trafficking pathways in guiding furrow formation is less clear. We demonstrate that a membrane trafficking pathway centered on Ras-like protein A (RalA) is required for fast furrow ingression in the early fly embryo. RalA function is absolutely required for furrow formation and initiation. In the absence of RalA and furrow function, chromosomal segregation is aberrant and polyploid nuclei are observed. RalA localizes to syncytial furrows, and mediates the movement of exocytic vesicles to the plasma membrane. Sec5, which is an exocyst complex subunit and localizes to ingressing furrows in wild-type embryos, becomes punctate and loses its cortical association in the absence of RalA function. Rab8 also fails to traffic to the plasma membrane and accumulates aberrantly in the cytoplasm in RalA disrupted embryos. RalA localization precedes F-actin recruitment to the furrow tip, suggesting that membrane trafficking might function upstream of cytoskeletal remodeling. These studies identify a pathway, which stretches from Rab8 to RalA and the exocyst complex, that mediates rapid furrow formation in early Drosophila embryos.
Pubmed ID: 26092850 RIS Download
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Collects, maintains and distributes Drosophila melanogaster strains for research. Emphasis is placed on genetic tools that are useful to a broad range of investigations. These include basic stocks of flies used in genetic analysis such as marker, balancer, mapping, and transposon-tagging strains; mutant alleles of identified genes, including a large set of transposable element insertion alleles; defined sets of deficiencies and a variety of other chromosomal aberrations; engineered lines for somatic and germline clonal analysis; GAL4 and UAS lines for targeted gene expression; enhancer trap and lacZ-reporter strains with defined expression patterns for marking tissues; and a collection of transposon-induced lethal mutations.
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