부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.mod.2006.08.004 Byline: Gudrun Wahlstrom (a), Hanna-Leena Norokorpi (a), Tapio I. Heino (a)(b) Keywords: [alpha]-Actinin mutant; Ena; Integrin; Usp; Oogenesis; Dorsal appendages; Stress fibres Abstract: [alpha]-Actinin is an evolutionarily conserved actin filament crosslinking protein with functions in both muscle and non-muscle cells. In non-muscle cells, interactions between [alpha]-actinin and its many binding partners regulate cell adhesion and motility. In Drosophila, one non-muscle and two muscle-specific [alpha]-actinin isoforms are produced by alternative splicing of a single gene. In wild-type ovaries, [alpha]-actinin is ubiquitously expressed. The non-muscle [alpha]-actinin mutant Actn.sup.[DELTA]233 , which is viable and fertile, lacks [alpha]-actinin expression in ovarian germline cells, while somatic follicle cells express [alpha]-actinin at late oogenesis. Here we show that this latter population of [alpha]-actinin, termed FC-[alpha]-actinin, is absent from the dorsoanterior follicle cells, and we present evidence that this is the result of a negative regulation by combined Epidermal growth factor receptor (EGFR) and Decapentaplegic signalling. Furthermore, EGFR signalling increased the F-actin bundling activity of ectopically expressed muscle-specific [alpha]-actinin. We also describe a novel morphogenetic event in the follicle cells that occurs during egg elongation. This event involves a transient repolarisation of the basal actin fibres and the assembly of a posterior [beta]-integrin-dependent adhesion site accumulating [alpha]-actinin and Enabled. Clonal analysis using Actn null alleles demonstrated that although [alpha]-actinin was not necessary for actin fibre formation or maintenance, the cytoskeletal remodelling was perturbed, and Enabled did not localise in the posterior adhesion site. Nevertheless, epithelial morphogenesis proceeded normally. This work provides the first evidence that [alpha]-actinin is involved in the organisation of the cytoskeleton in a non-muscle tissue in Drosophila. Author Affiliation: (a) Developmental Biology Programme/Institute of Biotechnology, Viikki Biocenter, P.O. Box 56 (Viikinkaari 9), FIN-00014, University of Helsinki, Finland (b) Department of Environmental and Biological Sciences, Viikki Biocenter, P.O. Box 56 (Viikinkaari 5D), FIN-00014, University of Helsinki, Finland Article History: Received 16 December 2005; Revised 4 August 2006; Accepted 16 August 2006