Disruption of endoplasmic reticulum structure and integrity in lipotoxic cell death

Nica M. Borradaile, Xianlin Han, Jeffrey D. Harp, Sarah E. Gale, Daniel S. Ory, Jean E. Schaffer

Research output: Contribution to journalArticle

368 Scopus citations

Abstract

Cell dysfunction and death induced by lipid accumulation in nonadipose tissues, or lipotoxicity, may contribute to the pathogenesis of obesity and type 2 diabetes. However, the mechanisms leading to lipotoxic cell death are poorly understood. We recently reported that, in Chinese hamster ovary (CHO) cells and in H9c2 cardiomyoblasts, lipid overload induced by incubation with 500 μM palmitate leads to intracellular accumulation of reactive oxygen species, which subsequently induce endoplasmic reticulum (ER) stress and cell death. Here, we show that palmitate also impairs ER function through a more direct mechanism. Palmitate was rapidly incorporated into saturated phospholipid and triglyceride species in microsomal membranes of CHO cells. The resulting membrane remodeling was associated with dramatic dilatation of the ER and redistribution of protein-folding chaperones to the cytosol within 5 h, indicating compromised ER membrane integrity. Increasing β-oxidation, through the activation of AMP-activated protein kinase, decreased palmitate incorporation into microsomes, decreased the escape of chaperones to the cytosol, and decreased subsequent caspase activation and cell death. Thus, palmitate rapidly increases the saturated lipid content of the ER, leading to compromised ER morphology and integrity, suggesting that impairment of the structure and function of this organelle is involved in the cellular response to fatty acid overload.

Original languageEnglish (US)
Pages (from-to)2726-2737
Number of pages12
JournalJournal of lipid research
Volume47
Issue number12
DOIs
StatePublished - Dec 2006
Externally publishedYes

Keywords

  • Fatty acid
  • Lipid synthesis
  • Lipotoxicity
  • Palmitate

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Cell Biology

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  • Cite this

    Borradaile, N. M., Han, X., Harp, J. D., Gale, S. E., Ory, D. S., & Schaffer, J. E. (2006). Disruption of endoplasmic reticulum structure and integrity in lipotoxic cell death. Journal of lipid research, 47(12), 2726-2737. https://doi.org/10.1194/jlr.M600299-JLR200