High impact information on sdt

• Initially discovered in the landmark genetic screen for Drosophila developmental mutants, bazooka, crumbs, shotgun and stardust mutants exhibit severe disruption in apicobasal polarity in embryonic epithelia, resulting in multilayered epithelia, tissue disintegration, and defects in cuticle formation [1].
• Drosophila Stardust interacts with Crumbs to control polarity of epithelia but not neuroblasts [1].
• Here we report that stardust encodes single PDZ domain MAGUK (membrane-associated guanylate kinase) proteins that are expressed in all primary embryonic epithelia from the onset of gastrulation [1].
• The Stardust proteins represent versatile candidates as structural and possibly regulatory constituents of the SAC, a crucial element in the control of epithelial cell polarity [2].
• Cells lacking crumbs or the functionally related gene stardust fail to organize a continuous ZA and to maintain cell polarity [2].

Biological context of sdt

• In sdt mutant embryos CRB is present only during gastrulation, but becomes undetectable during germ band extension; the protein is again visible during early organogenesis, at the time when the sdt mutant phenotype becomes apparent [3].
• The Drosophila genes crumbs and stardust are involved in the biogenesis of adherens junctions [4].
• Loss-of-function mutations in the Drosophila genes crumbs and stardust lead to the loss of cell polarity in most ectodermally derived epithelia, followed in some, such as the epidermis, by extensive apoptosis [4].
• Although loss of function of the Crumbs or Stardust genes prevents the stabilization of a belt of adherens junctions at the apico-lateral border of the cells, no phenotype has been described for the Dpatj gene and its role in epithelial morphogenesis and polarity remains unknown [5].

Anatomical context of sdt

• Distinct roles of Bazooka and Stardust in the specification of Drosophila photoreceptor membrane architecture [6].
• Here, we show that the development of these cellular structures involves two distinct processes: the establishment of apical-basal polarity that requires Bazooka (Baz), and the regionalization of apical membrane into stalk membranes and rhabdomeres that requires Stardust (Sdt) [6].
• armadillo, bazooka, and stardust are critical for early stages in formation of the zonula adherens and maintenance of the polarized blastoderm epithelium in Drosophila [7].
• We propose to rename this PDZ protein after its vertebrate homolog, Patj (Pals-associated tight junction protein) [8].

Associations of sdt with chemical compounds

• We provide evidence that the genes crumbs (crb) and stardust (sdt) encode critical components of a pathway that acts at the apical pole of epithelial cells to control the cytoarchitecture of ectodermally derived epithelia of the Drosophila embryo [3].

Physical interactions of sdt

• Drosophila PATJ or Drosophila Lin-7 are stabilised whenever a Sdt variant that contains the respective binding site is present, independently of where the variant is localised [9].

Co-localisations of sdt

• Stardust colocalizes with Crumbs at the apicolateral boundary, although their expression patterns in sensory organs differ [1].

Other interactions of sdt

• Computer modelling in combination with in vitro studies reveals similar binding affinities of Drosophila Crumbs for the PDZ domains of Stardust and DmPar-6 [10].
• Drosophila Stardust is a partner of Crumbs in the control of epithelial cell polarity [2].
• In Drosophila, this complex colocalizes with the Crumbs-Stardust (Sdt)-Pals1-associated TJ protein (Patj) complex [11].
• Drosophila Crumbs also interacts with two other polarity genes, Stardust and Discs Lost [12].
• In mutations with an increased amount of cell death (knirps; stardust; fork head), this figure approaches 100% [13].

References