Elevated autophagy and mitochondrial dysfunction in the Smith-Lemli-Opitz syndrome

Shaohua Chang, Gongyi Ren, Robert D. Steiner, Louise Merkens, Jean Baptiste Roullet, Zeljka Korade, Paul J. DiMuzio, Thomas N. Tulenko

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Smith-Lemli-Opitz Syndrome (SLOS) is a congenital, autosomal recessivemetabolic and developmental disorder caused by mutations in the enzyme which catalyzes the reduction of 7-dehydrocholesterol (7DHC) to cholesterol. Herein we show that dermal fibroblasts obtained from SLOS children display increased basal levels of LC3B-II, the hallmark protein signifying increased autophagy. The elevated LC3B-II is accompanied by increased beclin-1 and cellular autophagosome content. We also show that the LC3B-II concentration in SLOS cells is directly proportional to the cellular concentration of 7DHC, suggesting that the increased autophagy is caused by 7DHC accumulation secondary to defective DHCR7. Further, the increased basal LC3B-II levels were decreased significantly by pretreating the cells with antioxidants implicating a role for oxidative stress in elevating autophagy in SLOS cells. Considering the possible source of oxidative stress, we examined mitochondrial function in the SLOS cells using JC-1 assay and found significant mitochondrial dysfunction compared to mitochondria in control cells. In addition, the levels of PINK1 which targets dysfunctional mitochondria for removal by the autophagic pathway are elevated in SLOS cells, consistent with mitochondrial dysfunction as a stimulant of mitophagy in SLOS. This suggests that the increase in autophagic activity may be protective, i.e., to remove dysfunctional mitochondria. Taken together, these studies are consistent with a role for mitochondrial dysfunction leading to increased autophagy in SLOS pathophysiology.

Original languageEnglish (US)
Pages (from-to)431-442
Number of pages12
JournalMolecular Genetics and Metabolism Reports
Volume1
DOIs
StatePublished - 2014

Keywords

  • 7-Dehydrocholesterol
  • Birth defects
  • Lysosomes
  • Mitophagy
  • β-hydroxysterol-Δ-reductase (DHCR7)

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Endocrinology

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    Chang, S., Ren, G., Steiner, R. D., Merkens, L., Roullet, J. B., Korade, Z., DiMuzio, P. J., & Tulenko, T. N. (2014). Elevated autophagy and mitochondrial dysfunction in the Smith-Lemli-Opitz syndrome. Molecular Genetics and Metabolism Reports, 1, 431-442. https://doi.org/10.1016/j.ymgmr.2014.09.005