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Rhomboid
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Symbol: rho Flybase ID: {Flybase_ID}
Synonyms: veinlet (ve) {GadFly}
Function: provein gene {LocusLink}
Keywords: {Keywords} {Interactive_Fly}


  • serine protease - transmembrane protein involved with Epidermal growth factor receptor signaling - required for the processing of Spitz, the Egfr ligand.
Function/Pathway
  • Regulates the cleavage of Spitz and turns it into a soluble active ligand of Egfr (Schweitzer et al., 1995)
  • Rhom contributes to the formation of denticle types 1-4 (Wiellette, 1999)
Genetic interactions
  • Collier/Knot
    • In col1 mutant discs, two types of changes are observed: first, whereas rho is only expressed in a few cells in the dorsal presumptive L4 vein, it is expressed in two to four rows of cells, rather than a single one, in the presumptive L3 vein (Fig. 4B). Second, the distance separating the L3 and residual L4 veins is reduced (Fig. 4B), suggesting a posterior shift, in addition to widening, of the presumptive L3m vein, compared with L3. (Crozatier, 2002)
    • In col1 mutant discs, the L3m rho and col expression domains partially overlapped, confirming that the position of L3m vein has been shifted posteriorwards by several cell diameters relative to wild type (Fig. 4C,D), as previously deduced from Ci labelling of 24 hours APF pupae (Fig. 2D). However, rho labelling did not abut the AP boundary, indicating that rho transcription remained repressed in the anterior cells, which express En (Blair, 1992) (Fig.4I) (Crozatier, 2002)
  • Spitz
    • Since Veinlet (rhom) activates Spitz and since Spitz is expressed everywhere (Rutledge et al., 1992), the stripes of veinlet (rhom) expression are believed to be a source of active Spitz.
  • Wingless
    • rhomboid expression is abolished by continuous and uniform expression of Wingless (using the transgene combination arm-Gal4/UAS-wg). Also delayed addition of Wingless up to mid-stage 11 with UAS-winglessts also wipes out rhomboid expression. Later ectopic expression, induced at late stage 11, inhibits rhomboid transcription only in the midventral region (Fig 3C), and if sibling embryos are left to develop, they make ectopic naked cuticle in the same region (Figure 3D) (Sanson, 1999)
  • Since rho activates Spitz and since Spitz is expressed everywhere the stripes of rho expression are believed to be a source of active Spitz
  • contributes to the formation of denticle types 1-4
Physical interactions
{Physical interactions}
Transcriptional Regulation
  • Wg signaling represses rho expression (Sanson et al., 1999; Gritzan et al ., 1999)
  • Hh and Serrate both contribute positively to rho expression while Serrate is negatively regulated by both Hh and Wg (Alexandre, 1999)
Structure
  • 7-transmembrane protein
Location (protein and transcript)
  • Embryo
    • In the ventral ectoderm of late embryos, veinlet is expressed in stripes at the posterior of the en domain, a region due to make denticles (Bier, 1990; O'Keefe, 1997; Szüts, 1997)
    • rhomboid is expressed in the cells secreting rows 2-4 (Fig 4B) (Sanson, 1999)
  • Wing imaginal discs
    • Expressed in the primordia of all the longitudial veins at the end of the 3rd larval instar, as well as in two stripes flanking the presumptive wing margin (Sturtevant, 1995)
    • In wild-type third instar imaginal discs, rho-expressing cells flanked the col expression domain on both sides, with one to two rows of intercalary cells expressing neither gene (Fig. 4C). (Crozatier, 2002)
Protein Modifications and Regulation
{Modifications}
Related to
  • Large protein family conserved from bacteria to man: novel family of proteases likely to be involved in a variety of different processes
  • Drosophila itself has seven different Rhomboid-like proteins, three of which (Rhomboid-1, Rhomboid-2 and Rhomboid-3) have been associated with EGF receptor signalling (Wasserman, J.D. et al. 2000; Guichard, A. et al. 2000)
Mutations
{Mutations}
Overexpression / Ectopic expression
{Overexpression}
Reagents
{Reagents}


 

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