Filamins are highly conserved actin-crosslinking proteins that regulate organization of the actin cytoskeleton. As key components of versatile signaling scaffolds, filamins are implicated in developmental anomalies and cancer. Multiple isoforms of filamins exist, raising the possibility of distinct functions for each isoform during development and in disease. Here, we provide an initial characterization of jitterbug (jbug), which encodes one of the two filamin-type proteins in Drosophila. We generate Jbug antiserum that recognizes all of the spliced forms and reveals differential expression of different Jbug isoforms during development, and a significant maternal contribution of Jbug protein. To reveal the function of Jbug isoforms, we create new genetic tools, including a null allele that deletes all isoforms, hypomorphic alleles that affect only a subset, and UAS lines for Gal4-driven expression of the major isoforms. Using these tools, we demonstrate that Jbug is required for viability and that specific isoforms are required in the formation of actin-rich protrusions including thoracic bristles in adults and ventral denticles in the embryo. We also show that specific isoforms of Jbug show differential localization within epithelia and that maternal and zygotic loss of jbug disrupts Crumbs (Crb) localization in several epithelial cell types.

中文翻译：

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果蝇细丝蛋白型蛋白 Jitterbug (Jbug) 在发育过程中的同种型特异性作用。

细丝蛋白是高度保守的肌动蛋白交联蛋白，可调节肌动蛋白细胞骨架的组织。作为多功能信号支架的关键成分，细丝蛋白与发育异常和癌症有关。存在多种细丝蛋白亚型，提高了每种亚型在发育和疾病中发挥不同功能的可能性。在这里，我们提供了 jitterbug (jbug) 的初步特征，它编码果蝇中的两种细丝蛋白类型之一。我们生成的 Jbug 抗血清可识别所有剪接形式并揭示不同 Jbug 亚型在发育过程中的差异表达，以及 Jbug 蛋白的重要母体贡献。为了揭示 Jbug 异构体的功能，我们创建了新的遗传工具，包括删除所有异构体的无效等位基因，仅影响一个子集的亚型等位基因，以及主要亚型的 Gal4 驱动表达的 UAS 系。使用这些工具，我们证明了 Jbug 是生存所必需的，并且特定的亚型是形成富含肌动蛋白的突起所必需的，包括成人的胸鬃和胚胎的腹侧小齿。我们还表明，Jbug 的特定亚型显示上皮细胞内的差异定位，并且 jbug 的母体和合子丢失会破坏几种上皮细胞类型中的面包屑 (Crb) 定位。