Changes in organelle position and epithelial architecture associated with loss of CrebA

• Published in: Biology open Vol. 4; no. 3; pp. 317 - 330
• Main Authors: Fox, Rebecca M, Andrew, Deborah J
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Ltd 15.03.2015; The Company of Biologists
• Subjects: Creb3-like; CrebA; Defects; Drosophila; Embryos; Epithelium; Genes; Localization; Membranes; Morphology; Mutants; Mutation; Organelles; Phenotypes; Salivary gland; Salivary glands; Secretion; Secretory organelles; Secretory vesicles; Septate junction; CrebA; Creb3-like; Secretion; Drosophila; Septate junction; Salivary gland; Secretory organelles
• ISSN: 2046-6390; 2046-6390
• DOI: 10.1242/bio.201411205

Drosophila CrebA facilitates high-level secretion by transcriptional upregulation of the protein components of the core secretory machinery. In CrebA mutant embryos, both salivary gland (SG) morphology and epidermal cuticle secretion are abnormal, phenotypes similar to those observed with mutations in core secretory pathway component genes. Here, we examine the cellular defects associated with CrebA loss in the SG epithelium. Apically localized secretory vesicles are smaller and less abundant, consistent with overall reductions in secretion. Unexpectedly, global mislocalization of cellular organelles and excess membrane accumulation in the septate junctions (SJs) are also observed. Whereas mutations in core secretory pathway genes lead to organelle localization defects similar to those of CrebA mutants, they have no effect on SJ-associated membrane. Mutations in tetraspanin genes, which are normally repressed by CrebA, have mild defects in SJ morphology that are rescued by simultaneous CrebA loss. Correspondingly, removal of several tetraspanins gives partial rescue of the CrebA SJ phenotype, supporting a role for tetraspanins in SJ organization.