The Journal of Neuroscience, June 28, 2006, ():
Heparan Sulphation Patterns Generated by Specific Heparan Sulfotransferase Enzymes Direct Distinct Aspects of Retinal Axon Guidance at the Optic Chiasm
J. Neurosci. Pratt et al.
26: 6911
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Supplementary Figure S 1
(A) Summary of heparan sulphate proteoglycan (HSPG) biosynthesis. Glycosaminoglycan (GAG) side chains are added to HSPG core proteins by a series of enzymes including EXT1. The GAG chains are then modified by enzymes including heparan sulphotransferase (HST) enzymes Hs2st and Hs6st1 which add sulphate groups in chemically distinct patterns designated as ‘2S’ and ‘6S’. (B) Abolition of GAG synthesis and subsequent HSPG sulphation by conditional ablation of the EXT1 gene (Nes; EXT1-/- mutants) results in numerous RGCs misprojecting to the opposite eye. The chiasm structure in these mutants was not reported in detail so is marked ‘?’. Based on data from Inatini et al., 2003. (C) Summary of Slit1 and Slit2 expression and the RGC axon navigation errors made in Slit1-/-; Slit2-/- double mutants (based on data from Erskine et al., 2000; Plump et al., 2002). There is considerable co-incidence between regions expressing Slit 1/2 and those expressing Hs2st (Fig. 6) and/or Hs6st1 (Fig. 7). There is also a striking resemblance between the mutant phenotypes; Hs6st1-/- (Fig. 4) phenocopies the misprojection into the opposite eye seen in Slit double mutants and the disorganisation at the chiasm seen is Hs2st-/- mutants (Fig. 3) is reminiscent of the Slit double mutant phenotype. Note that we did not see the ‘ectopic chiasm’ characteristic of Slit double mutants in either the Hs2st or Hs6st1 mutants. Abbreviations: distal (Di); proximal (Pr); anterior (A); posterior (P).
