Snee Mark J, Macdonald Paul M
Institute for Cellular and Molecular Biology, Section of Molecular, Cell, and Developmental Biology, University of Texas, Austin, Texas 78712, USA.
Dev Biol. 2009 Apr 15;328(2):434-44. doi: 10.1016/j.ydbio.2009.02.003. Epub 2009 Feb 13.
Bicaudal C and trailer hitch are both required for dorsoventral patterning of the Drosophila oocyte. Each mutant produces ventralized eggs, a phenotype typically associated with failure of the oocyte to provide a dorsalization signal--the Gurken protein--to the follicle cells. Bicaudal C and trailer hitch are both implicated in post-transcriptional gene regulation. Bicaudal C acts in recruiting a deadenylase to specific mRNAs, leading to translational repression. The role of trailer hitch is less well defined, but mutants have defects in protein secretion, and show aberrant distribution of an endoplasmic reticulum exit site marker whose mRNA is associated with Trailer hitch protein. We show that Bicaudal C and trailer hitch interact genetically. Mutants of these two genes have shared defects in localization of gurken and other anteriorly-localized mRNAs, as well as altered microtubule organization which may underlie the mRNA localization defects. Bicaudal C and trailer hitch mutants also share a syndrome of actin-related abnormalities, including the formation of ectopic actin cages near the anterior of the oocyte. The cages sequester Gurken protein, blocking its secretion and thus interfering with signaling of the follicle cells to specify dorsal fate.
双尾C和拖车挂钩蛋白对于果蝇卵母细胞的背腹模式形成都是必需的。每个突变体都会产生腹化的卵，这种表型通常与卵母细胞无法向滤泡细胞提供背化信号—— Gurken蛋白——有关。双尾C和拖车挂钩蛋白都与转录后基因调控有关。双尾C作用于招募一种去腺苷酸化酶到特定的mRNA上，导致翻译抑制。拖车挂钩蛋白的作用尚不清楚，但突变体在蛋白质分泌方面存在缺陷，并且显示出一种内质网出口位点标记物的异常分布，其mRNA与拖车挂钩蛋白相关。我们发现双尾C和拖车挂钩蛋白在遗传上相互作用。这两个基因的突变体在gurken和其他前部定位的mRNA的定位上存在共同缺陷，以及微管组织的改变，这可能是mRNA定位缺陷的基础。双尾C和拖车挂钩蛋白突变体还存在一系列与肌动蛋白相关的异常，包括在卵母细胞前部附近形成异位肌动蛋白笼。这些笼子隔离了Gurken蛋白，阻止其分泌，从而干扰滤泡细胞指定背侧命运的信号传递。
