copi vesicle transport is a common requirement for tube expansion in drosophilacopi囊泡运输管是一种常见的要求在果蝇的扩张.pdfVIP

COPI Vesicle Transport Is a Common Requirement for Tube Expansion in Drosophila . ´ . ´ ´ ¨ ¨ Satish Arcot Jayaram , Kirsten-Andre Senti , Katarına Tiklova, Vasilios Tsarouhas, Johanna Hemphala, Christos Samakovlis* Department of Developmental Biology, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden Abstract Background: Tube expansion defects like stenoses and atresias cause devastating human diseases. Luminal expansion during organogenesis begins to be elucidated in several systems but we still lack a mechanistic view of the process in many organs. The Drosophila tracheal respiratory system provides an amenable model to study tube size regulation. In the trachea, COPII anterograde transport of luminal proteins is required for extracellular matrix assembly and the concurrent tube expansion. Principal Findings: We identified and analyzed Drosophila COPI retrograde transport mutants with narrow tracheal tubes. cCOP mutants fail to efficiently secrete luminal components and assemble the luminal chitinous matrix during tracheal tube expansion. Likewise, tube extension is defective in salivary glands, where it also coincides with a failure in the luminal deposition and assembly of a distinct, transient intraluminal matrix. Drosophila cCOP colocalizes with cis-Golgi markers and in cCOP mutant embryos the ER and Golgi structures are severely disrupted. Analysis of cCOP and Sar1 double mutants suggests that bidirectional ER-Golgi traffic maintains the ER and Golgi compartments and is required for secretion and assembly of luminal matrixes during tube expansion. Conclusions/Significance: Our results demonstrate