title: Differential range and activity of various forms of the Hedgehog protein.
abstract: BACKGROUND
  The Hedgehog (Hh) family of secreted proteins act as extracellular messengers to control and coordinate growth and differentiation. The mechanism by which Hh protein travels across a field of cells, and results in a range of specific effects relating to the distance from the source, has been the subject of much debate. It has been suggested that the range and activity of the pathway can be linked to modifications of the Hh protein, specifically the addition of lipid groups at N- and C-terminal sites.
  
  
  RESULTS
  Here we have addressed the potency of different forms of Hh protein by expressing these in Drosophila, where we are able to precisely establish pathway activity and range in naïve but responsive tissues. As expected, a construct that can produce all forms of Hh recapitulates endogenous signaling potencies. In comparison, expression of a form that lacks the cholesterol moiety (HhN) leads to an extended range, but the product is less effective at inducing maximal Hh responses. Expression of a point mutant that lacks the N-terminal palmitate binding site shows that the palmitoylation of Hh is absolutely required for activity in this system.
  
  
  CONCLUSIONS
  We conclude that the addition of the cholesterol moiety limits the range of the protein and is required for maximal activity, while addition of palmitate is required for all activity. These findings have implications for understanding how Hedgehog proteins move, and thus their potential at influencing distant sites, and concomitantly, how modifications of the signaling protein can affect the efficacy of the response in exposed cells.
authors.affiliation: MRC Functional Genetics Unit, Department of Human Anatomy and Genetics, University of Oxford, Oxford, UK. Rebecca.dawber@anat.ox.ac.uk
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Dawber
authors.forename: Stephen
authors.initials: S
authors.lastname: Hebbes
authors.forename: Bram
authors.initials: B
authors.lastname: Herpers
authors.forename: France
authors.initials: F
authors.lastname: Docquier
authors.forename: Marcel
authors.initials: M
authors.lastname: van den Heuvel
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002784:Cholesterol; D004330:Drosophila; D029721:Drosophila Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D053823:Hedgehog Proteins; D007814:Larva; D019308:Palmitic Acid; D017354:Point Mutation; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D014921:Wings, Animal / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D053823:Hedgehog Proteins; C077245:hh protein, Drosophila; D019308:Palmitic Acid; D002784:Cholesterol