Fig. 7. Shh signaling and cholesterol synthesis. (A) Various DHCR7 mutant constructs. (B) Inhibition Hh signaling is enhanced by treatment with AY-9944. Embryos were injected with the reporter construct 8X3'Gli-BS Luc with or without Shh-N, DHCR7 mRNA and treatment with 10 µM AY-9944. (C-J) Microinjection of DHCR7 mutants that are defective in reductase activity causes cyclopic phenotypes. The overexpression of DHCR7 mRNA (E) or treatment with AY-9944 (D) caused minor defects, but a combination of both causes severe defects (F). Embryonic phenotypes caused by microinjection of 1 ng of DHCR7^R350W (H), DHCR7^IVS8-1G>C (G), DHCR7^N (J) and DHCR7^W149X (I) mutants. (K) Pax6 staining of tailbud stage embryos injected with DHCR7^R350W. Arrow marks `cyclopic' eye. (L) Modulation of Gli reporter by DHCR7 mutants using animal cap conjugation. Embryos were injected with Chordin (with or without Shh-N mRNA) or with Gli-BS Luc (with or without DHCR7 mRNA).