Deoxysphingolipids, Novel Biomarkers for Type 2 Diabetes, Are Cytotoxic for Insulin-Producing Cells

  1. Sabrina Sonda7
  1. 1Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital Zurich, Zurich, Switzerland
  2. 2Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
  3. 3Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
  4. 4Competence Centre for Systems Physiology and Metabolic Diseases, Zurich, Switzerland
  5. 5Institute of Parasitology, University of Zurich, Zurich, Switzerland
  6. 6Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
  7. 7Swiss Hepato-Pancreatico-Biliary (HPB)-Center, Division of Surgical Research, Department of Visceral and Transplantation Surgery, University Hospital Zurich, Zurich, Switzerland
  1. Corresponding author: Sabrina Sonda, sabrina.sonda{at}usz.ch.
  1. R.A.Z. and T.H. contributed equally to this work.

Abstract

Irreversible failure of pancreatic β-cells is the main culprit in the pathophysiology of diabetes, a disease that is now a global epidemic. Recently, elevated plasma levels of deoxysphingolipids, including 1-deoxysphinganine, have been identified as a novel biomarker for the disease. In this study, we analyzed whether deoxysphingolipids directly compromise the functionality of insulin-producing Ins-1 cells and primary islets. Treatment with 1-deoxysphinganine induced dose-dependent cytotoxicity with senescent, necrotic, and apoptotic characteristics and compromised glucose-stimulated insulin secretion. In addition, 1-deoxysphinganine altered cytoskeleton dynamics, resulting in intracellular accumulation of filamentous actin and activation of the Rho family GTPase Rac1. Moreover, 1-deoxysphinganine selectively upregulated ceramide synthase 5 expression and was converted to 1-deoxy-dihydroceramides without altering normal ceramide levels. Inhibition of intracellular 1-deoxysphinganine trafficking and ceramide synthesis improved the viability of the cells, indicating that the intracellular metabolites of 1-deoxysphinganine contribute to its cytotoxicity. Analyses of signaling pathways identified Jun N-terminal kinase and p38 mitogen-activated protein kinase as antagonistic effectors of cellular senescence. The results revealed that 1-deoxysphinganine is a cytotoxic lipid for insulin-producing cells, suggesting that the increased levels of this sphingolipid observed in diabetic patients may contribute to the reduced functionality of pancreatic β-cells. Thus, targeting deoxysphingolipid synthesis may complement the currently available therapies for diabetes.

Footnotes

  • Received July 3, 2013.
  • Accepted December 14, 2013.

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  1. Diabetes vol. 63 no. 4 1326-1339
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