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Increased fatty acid desaturation and enhanced expression of stearoyl coenzyme A desaturase protects pancreatic beta-cells from lipoapoptosis


Increased availability of fatty acids causes cell death and dysfunction in beta-cell lines, isolated islets, and animal models of diabetes. From the MIN6 beta-cell line, we selected two subpools that are resistant to palmitate-induced apoptosis. Protection was not universal because palmitate-resistant cells remained sensitive to cytokine- and streptozotocin-induced apoptosis. Palmitate oxidation and incorporation into cholesterol ester (but not triglycerides) were significantly higher in palmitate-resistant cells than in control cells. Consistent with these findings, transcript profiling revealed increased expression in palmitate-resistant cells of several beta-oxidation genes as well as a 2.8-fold upregulation of stearoyl-CoA desaturase 1 (SCD1). Correspondingly, the oleate-to-palmitate ratio of palmitate-resistant cells was double that of palmitate-pretreated control cells. At least some of this additional oleate in palmitate-resistant cells was incorporated into cholesterol ester stored in the form of large cytosolic lipid bodies. However, blocking cholesterol ester formation did not render palmitate-resistant cells sensitive to palmitate-induced apoptosis. On the other hand, an inhibitor of SCD1, 10,12-conjugated linoleic acid, dose dependently overcame the resistance of palmitate-resistant cells to lipoapoptosis. Our results suggest that desaturation per se is more important in protecting beta-cells from the cytotoxic effects of palmitate than is the nature of neutral lipid storage pool thus generated.

Type Journal
ISBN 0012-1797 (Print)
Authors Busch, A. K.;Gurisik, E.;Cordery, D. V.;Sudlow, M.;Denyer, G. S.;Laybutt, D. R.;Hughes, W. E.;Biden, T. J. :
Responsible Garvan Author A/Prof Ross Laybutt
Publisher Name DIABETES
Published Date 2005-01-01
Published Volume 54
Published Issue 10
Published Pages 2917-24
Status Published in-print
URL link to publisher's version