Severe facial clefting in Insig-deficient mouse embryos caused by sterol accumulation and reversed by lovastatin

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Abstract

Insig-1 and Insig-2 are regulatory proteins that restrict the cholesterol biosynthetic pathway by preventing proteolytic activation of SREBPs and by enhancing degradation of HMG-CoA reductase. Here, we created Insig-double-knockout (Insig-DKO) mice that are homozygous for null mutations in Insig-1 and Insig-2. After 18.5 days of development, 96% of Insig-DKO embryos had defects in midline facial development, ranging from cleft palate (52%) to complete cleft face (44%). Middle and inner ear structures were abnormal, but teeth and skeletons were normal. The animals were lethargic and runted; they died within 1 day of birth. The livers and heads of Insig-DKO embryos overproduced sterols, causing a marked buildup of sterol intermediates. Treatment of pregnant mice with the HMG-CoA reductase inhibitor lovastatin reduced sterol synthesis in Insig-DKO embryos and reduced the pre-cholesterol intermediates. This treatment ameliorated the clefting syndrome so that 54% of Insig-DKO mice had normal faces, and only 7% had cleft faces. We conclude that buildup of pre-cholesterol sterol intermediates interferes with midline fusion of facial structures in mice. These findings have implications for the pathogenesis of the cleft palate component of Smith-Lemli-Opitz syndrome and other human malformation syndromes in which mutations in enzymes catalyzing steps in cholesterol biosynthesis produce a buildup of sterol intermediates.

Original languageEnglish (US)
Pages (from-to)2356-2365
Number of pages10
JournalJournal of Clinical Investigation
Volume116
Issue number9
DOIs
StatePublished - Sep 1 2006

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Lovastatin
Sterols
Embryonic Structures
Cholesterol
Cleft Palate
Knockout Mice
Smith-Lemli-Opitz Syndrome
Hydroxymethylglutaryl CoA Reductases
Hydroxymethylglutaryl-CoA Reductase Inhibitors
Mutation
Biosynthetic Pathways
Middle Ear
Inner Ear
Skeleton
Tooth
Head
Parturition
Liver
Enzymes
Therapeutics

ASJC Scopus subject areas

  • Medicine(all)

Cite this

@article{571f845e31504912814cc64eb56a58f0,
title = "Severe facial clefting in Insig-deficient mouse embryos caused by sterol accumulation and reversed by lovastatin",
abstract = "Insig-1 and Insig-2 are regulatory proteins that restrict the cholesterol biosynthetic pathway by preventing proteolytic activation of SREBPs and by enhancing degradation of HMG-CoA reductase. Here, we created Insig-double-knockout (Insig-DKO) mice that are homozygous for null mutations in Insig-1 and Insig-2. After 18.5 days of development, 96{\%} of Insig-DKO embryos had defects in midline facial development, ranging from cleft palate (52{\%}) to complete cleft face (44{\%}). Middle and inner ear structures were abnormal, but teeth and skeletons were normal. The animals were lethargic and runted; they died within 1 day of birth. The livers and heads of Insig-DKO embryos overproduced sterols, causing a marked buildup of sterol intermediates. Treatment of pregnant mice with the HMG-CoA reductase inhibitor lovastatin reduced sterol synthesis in Insig-DKO embryos and reduced the pre-cholesterol intermediates. This treatment ameliorated the clefting syndrome so that 54{\%} of Insig-DKO mice had normal faces, and only 7{\%} had cleft faces. We conclude that buildup of pre-cholesterol sterol intermediates interferes with midline fusion of facial structures in mice. These findings have implications for the pathogenesis of the cleft palate component of Smith-Lemli-Opitz syndrome and other human malformation syndromes in which mutations in enzymes catalyzing steps in cholesterol biosynthesis produce a buildup of sterol intermediates.",
author = "Engelking, {Luke J.} and Evers, {Bret M.} and Richardson, {James A.} and Goldstein, {Joseph L.} and Brown, {Michael S.} and Guosheng Liang",
year = "2006",
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T1 - Severe facial clefting in Insig-deficient mouse embryos caused by sterol accumulation and reversed by lovastatin

AU - Engelking, Luke J.

AU - Evers, Bret M.

AU - Richardson, James A.

AU - Goldstein, Joseph L.

AU - Brown, Michael S.

AU - Liang, Guosheng

PY - 2006/9/1

Y1 - 2006/9/1

N2 - Insig-1 and Insig-2 are regulatory proteins that restrict the cholesterol biosynthetic pathway by preventing proteolytic activation of SREBPs and by enhancing degradation of HMG-CoA reductase. Here, we created Insig-double-knockout (Insig-DKO) mice that are homozygous for null mutations in Insig-1 and Insig-2. After 18.5 days of development, 96% of Insig-DKO embryos had defects in midline facial development, ranging from cleft palate (52%) to complete cleft face (44%). Middle and inner ear structures were abnormal, but teeth and skeletons were normal. The animals were lethargic and runted; they died within 1 day of birth. The livers and heads of Insig-DKO embryos overproduced sterols, causing a marked buildup of sterol intermediates. Treatment of pregnant mice with the HMG-CoA reductase inhibitor lovastatin reduced sterol synthesis in Insig-DKO embryos and reduced the pre-cholesterol intermediates. This treatment ameliorated the clefting syndrome so that 54% of Insig-DKO mice had normal faces, and only 7% had cleft faces. We conclude that buildup of pre-cholesterol sterol intermediates interferes with midline fusion of facial structures in mice. These findings have implications for the pathogenesis of the cleft palate component of Smith-Lemli-Opitz syndrome and other human malformation syndromes in which mutations in enzymes catalyzing steps in cholesterol biosynthesis produce a buildup of sterol intermediates.

AB - Insig-1 and Insig-2 are regulatory proteins that restrict the cholesterol biosynthetic pathway by preventing proteolytic activation of SREBPs and by enhancing degradation of HMG-CoA reductase. Here, we created Insig-double-knockout (Insig-DKO) mice that are homozygous for null mutations in Insig-1 and Insig-2. After 18.5 days of development, 96% of Insig-DKO embryos had defects in midline facial development, ranging from cleft palate (52%) to complete cleft face (44%). Middle and inner ear structures were abnormal, but teeth and skeletons were normal. The animals were lethargic and runted; they died within 1 day of birth. The livers and heads of Insig-DKO embryos overproduced sterols, causing a marked buildup of sterol intermediates. Treatment of pregnant mice with the HMG-CoA reductase inhibitor lovastatin reduced sterol synthesis in Insig-DKO embryos and reduced the pre-cholesterol intermediates. This treatment ameliorated the clefting syndrome so that 54% of Insig-DKO mice had normal faces, and only 7% had cleft faces. We conclude that buildup of pre-cholesterol sterol intermediates interferes with midline fusion of facial structures in mice. These findings have implications for the pathogenesis of the cleft palate component of Smith-Lemli-Opitz syndrome and other human malformation syndromes in which mutations in enzymes catalyzing steps in cholesterol biosynthesis produce a buildup of sterol intermediates.

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