Absence of ventral cell populations in the developing brain in a rat model of the Smith-Lemli-Opitz syndrome.
The Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive condition involving craniofacial and central nervous system malformations with occasional holoprosencephaly (HPE). It is caused by a defect in the 7-dehydrocholesterol (7-DHC) reductase, the enzyme catalyzing the last step of cholesterol biosynthesis. Treatment of pregnant rats with inhibitors of 7-DHC reductase, either AY9944 or BM15.766, has provided a valuable model to study the pathogenesis in SLOS. Recently, cholesterol has been shown to be involved in the post-translational activation of the signaling protein Sonic Hedgehog. To identify the early defects associated with HPE in a rat model of SLOS, and to compare the phenotype of the treated embryos with that of the Shh(-/-) mutants, we examined brain morphology and expression of three developmental genes (Shh, Otx2, and Pax6 ) in 23-somite stage embryos from AY9944-treated dams. We report clearly abnormal morphology of the developing brain, concerning primarily the ventral aspect of the neural tube. We observed a reduced or absent expression of Shh and Otx2 in their ventral domain associated with extended ventral expression of Pax6. The results suggest an absence of the midline ventral cell type at all levels of the cranial neural tube. They provide further evidence that cholesterol-deficiency-induced HPE originates from impaired Shh signaling activity in the ventral neural tube.
Gofflot
F
F
Unit of Developmental Genetics, Université Catholique de Louvain, Bruxelles, Belgium. francoise.gofflot@gede.ucl.ac.be
Kolf-Clauw
M
M
Clotman
F
F
Roux
C
C
Picard
J J
JJ
D000818:Animals; D001921:Brain / Q000196:embryology / Q000473:pathology*; D002784:Cholesterol / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D004195:Disease Models, Animal; D005314:Embryonic and Fetal Development / Q000235:genetics; D004791:Enzyme Inhibitors / Q000633:toxicity*; D005136:Eye Proteins; D005260:Female; D005315:Fetal Diseases / Q000139:chemically induced; D005326:Fetal Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency* / Q000235:genetics; D005865:Gestational Age; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D008297:Male; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D009436:Neural Tube Defects / Q000139:chemically induced / Q000196:embryology* / Q000235:genetics; D009474:Neurons / Q000473:pathology*; D051857:Otx Transcription Factors; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000172:deficiency* / Q000235:genetics; D044925:Oxidoreductases Acting on CH-CH Group Donors; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D011247:Pregnancy; D016548:Prosencephalon / Q000196:embryology / Q000473:pathology; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012097:Repressor Proteins; D012249:Rhombencephalon / Q000196:embryology / Q000473:pathology; D015398:Signal Transduction / Q000502:physiology; D019082:Smith-Lemli-Opitz Syndrome / Q000235:genetics; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D001371:trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride / Q000633:toxicity*
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005136:Eye Proteins; D005326:Fetal Proteins; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D051857:Otx Transcription Factors; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605733:Pax6 protein, rat; D011506:Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D001371:trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride; D002784:Cholesterol; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019995:7-dehydrocholesterol reductase