Alterations in membrane caveolae and BK Ca channel activity in skin fibroblasts in Smith-Lemli-Opitz syndrome

Gongyi Ren, Robert F. Jacob, Yuri Kaulin, Paul DiMuzio, Yi Xie, R. Preston Mason, G. Stephen Tint, Robert D. Steiner, Jean-Baptiste Roullet, Louise Merkens, Diana Whitaker-Menezes, Philippe G. Frank, Michael P. Lisanti, Robert H. Cox, Thomas N. Tulenko

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The Smith-Lemli-Opitz syndrome (SLOS) is an inherited disorder of cholesterol synthesis caused by mutations in DHCR7 which encodes the final enzyme in the cholesterol synthesis pathway. The immediate precursor to cholesterol synthesis, 7-dehydrocholesterol (7-DHC) accumulates in the plasma and cells of SLOS patients which has led to the idea that the accumulation of abnormal sterols and/or reduction in cholesterol underlies the phenotypic abnormalities of SLOS. We tested the hypothesis that 7-DHC accumulates in membrane caveolae where it disturbs caveolar bilayer structure-function. Membrane caveolae from skin fibroblasts obtained from SLOS patients were isolated and found to accumulate 7-DHC. In caveolar-like model membranes containing 7-DHC, subtle, but complex alterations in intermolecular packing, lipid order and membrane width were observed. In addition, the BK Ca K + channel, which co-migrates with caveolin-1 in a membrane fraction enriched with cholesterol, was impaired in SLOS cells as reflected by reduced single channel conductance and a 50mV rightward shift in the channel activation voltage. In addition, a marked decrease in BK Ca protein but not mRNA expression levels was seen suggesting post-translational alterations. Accompanying these changes was a reduction in caveolin-1 protein and mRNA levels, but membrane caveolar structure was not altered. These results are consistent with the hypothesis that 7-DHC accumulation in the caveolar membrane results in defective caveolar signaling. However, additional cellular alterations beyond mere changes associated with abnormal sterols in the membrane likely contribute to the pathogenesis of SLOS.

Original languageEnglish (US)
Pages (from-to)346-355
Number of pages10
JournalMolecular Genetics and Metabolism
Volume104
Issue number3
DOIs
StatePublished - Nov 2011

Fingerprint

Smith-Lemli-Opitz Syndrome
Large-Conductance Calcium-Activated Potassium Channels
Caveolae
Fibroblasts
Skin
Membranes
Cholesterol
Caveolin 1
Sterols
Messenger RNA
Membrane structures
Caveolins
Membrane Lipids
Plasma Cells
Proteins
Chemical activation
7-dehydrocholesterol
Plasmas
Electric potential
Enzymes

Keywords

  • β-hydroxy-steroid-Δ -reductase (DHCR7)
  • 7-dehydrocholesterol
  • Birth defects
  • Caveolin-1
  • Lipid rafts
  • Membrane structure/function

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Genetics
  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Alterations in membrane caveolae and BK Ca channel activity in skin fibroblasts in Smith-Lemli-Opitz syndrome. / Ren, Gongyi; Jacob, Robert F.; Kaulin, Yuri; DiMuzio, Paul; Xie, Yi; Mason, R. Preston; Tint, G. Stephen; Steiner, Robert D.; Roullet, Jean-Baptiste; Merkens, Louise; Whitaker-Menezes, Diana; Frank, Philippe G.; Lisanti, Michael P.; Cox, Robert H.; Tulenko, Thomas N.

In: Molecular Genetics and Metabolism, Vol. 104, No. 3, 11.2011, p. 346-355.

Research output: Contribution to journalArticle

Ren, G, Jacob, RF, Kaulin, Y, DiMuzio, P, Xie, Y, Mason, RP, Tint, GS, Steiner, RD, Roullet, J-B, Merkens, L, Whitaker-Menezes, D, Frank, PG, Lisanti, MP, Cox, RH & Tulenko, TN 2011, 'Alterations in membrane caveolae and BK Ca channel activity in skin fibroblasts in Smith-Lemli-Opitz syndrome', Molecular Genetics and Metabolism, vol. 104, no. 3, pp. 346-355. https://doi.org/10.1016/j.ymgme.2011.04.019
Ren, Gongyi ; Jacob, Robert F. ; Kaulin, Yuri ; DiMuzio, Paul ; Xie, Yi ; Mason, R. Preston ; Tint, G. Stephen ; Steiner, Robert D. ; Roullet, Jean-Baptiste ; Merkens, Louise ; Whitaker-Menezes, Diana ; Frank, Philippe G. ; Lisanti, Michael P. ; Cox, Robert H. ; Tulenko, Thomas N. / Alterations in membrane caveolae and BK Ca channel activity in skin fibroblasts in Smith-Lemli-Opitz syndrome. In: Molecular Genetics and Metabolism. 2011 ; Vol. 104, No. 3. pp. 346-355.
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abstract = "The Smith-Lemli-Opitz syndrome (SLOS) is an inherited disorder of cholesterol synthesis caused by mutations in DHCR7 which encodes the final enzyme in the cholesterol synthesis pathway. The immediate precursor to cholesterol synthesis, 7-dehydrocholesterol (7-DHC) accumulates in the plasma and cells of SLOS patients which has led to the idea that the accumulation of abnormal sterols and/or reduction in cholesterol underlies the phenotypic abnormalities of SLOS. We tested the hypothesis that 7-DHC accumulates in membrane caveolae where it disturbs caveolar bilayer structure-function. Membrane caveolae from skin fibroblasts obtained from SLOS patients were isolated and found to accumulate 7-DHC. In caveolar-like model membranes containing 7-DHC, subtle, but complex alterations in intermolecular packing, lipid order and membrane width were observed. In addition, the BK Ca K + channel, which co-migrates with caveolin-1 in a membrane fraction enriched with cholesterol, was impaired in SLOS cells as reflected by reduced single channel conductance and a 50mV rightward shift in the channel activation voltage. In addition, a marked decrease in BK Ca protein but not mRNA expression levels was seen suggesting post-translational alterations. Accompanying these changes was a reduction in caveolin-1 protein and mRNA levels, but membrane caveolar structure was not altered. These results are consistent with the hypothesis that 7-DHC accumulation in the caveolar membrane results in defective caveolar signaling. However, additional cellular alterations beyond mere changes associated with abnormal sterols in the membrane likely contribute to the pathogenesis of SLOS.",
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AU - DiMuzio, Paul

AU - Xie, Yi

AU - Mason, R. Preston

AU - Tint, G. Stephen

AU - Steiner, Robert D.

AU - Roullet, Jean-Baptiste

AU - Merkens, Louise

AU - Whitaker-Menezes, Diana

AU - Frank, Philippe G.

AU - Lisanti, Michael P.

AU - Cox, Robert H.

AU - Tulenko, Thomas N.

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