High impact information on S

• Both Star and Rhomboid-1 have been assumed to work at the cell surface to control ligand activation [1].
• Coexpression of Star promotes translocation of Spi to a compartment where Rho is present both in cells and in embryos [2].
• Intracellular trafficking by Star regulates cleavage of the Drosophila EGF receptor ligand Spitz [2].
• We also obtained dominant-negative and neomorphic Star mutations, which have phenotypes similar to those of rho NOVA alleles, as well as dominant-negative Egf-r alleles [3].
• To gain insights into the mechanisms underlying Rho and Star function, we developed a mutagenesis scheme to isolate novel overexpression activity (NOVA) alleles [3].

Biological context of S

• Enhancer trap insertions reveal that Star expression in the eye disc is restricted to the developing R8, R2, and R5 cells [4].
• Early in oogenesis, Star mRNA expression is higher in StarKojak egg chambers than in wild-type egg chambers, consistent with its gain-of-function phenotype [5].
• The Star/asteroid (S/ast) region of Drosophila melanogaster has been cloned by P element transposon tagging using the snw chromosome as a source of defective P elements [6].
• Complete loss of Star function during retinal development, analyzed in mosaic animals, results in cell death, visible as scars in the adult eye [7].

Anatomical context of S

• Taken together with the expression pattern at the morphogenetic furrow, these results demonstrate an early role for Star in photoreceptor development [8].
• Here, we show that the Star protein is expressed perinuclearly in the early female germline and later is found in the oocyte cytoplasm [9].
• The loss-of-function Star mutation (StarX155) dominantly suppressed the defects in the argos optic lobes, suggesting that these two genes act in an antagonistic fashion during optic lobe development [10].

Physical interactions of S

• We show that alleles of Gl and dynein genetically interact with both Star and EGFR alleles [11].

Regulatory relationships of S

• rhomboid and Star interact synergistically to promote EGFR/MAPK signaling during Drosophila wing vein development [12].

Other interactions of S

• The ventrolateral genes include spitz, which encodes an EGF-like ligand, and Star [13].
• This observation suggests a sequential activity of Star and Rho in mSpi processing [2].
• However, a mutant form of mSpi that is not cleaved still signals to DER in a Rhomboid and Star-dependent manner [14].
• The ectodermal defects of spitz, rho or Star mutant embryos could be rescued by inducing the expression of the respective normal genes only in the midline cells [15].
• Mutations in Star and l(2)43Bb had no significant effect upon the lambdatop eggshell defect whereas smt3 and dock alleles significantly suppressed the lambdatop phenotype [16].

Analytical, diagnostic and therapeutic context of S

• Expression in mammalian cell cultures reveals interdependent, but distinct, functions for Star and Rhomboid proteins in the processing of the Drosophila transforming-growth-factor-alpha homologue Spitz [17].

References