ARS | Publication request: Disruption of the human CGI-58 homologue in Arabidopsis results in lipid droplet accumulation in the cytosol of plant cells

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 15, 2010
Publication Date: July 25, 2010
Citation: James, C.N., Horn, P.J., Richardson, C.C., Gidda, S.K., Zhang, D., Mullen, R.T., Dyer, J.M., Anderson, R.G., and Chapman, K.D. (2010). Disruption of the human CGI-58 homologue in Arabidopsis results in lipid droplet accumulation in the cytosol of plant cells. FASEB Summer Research Conferences, Lipid Droplets: Metabolic Consequences of the Storage of Neutral Lipids. July 25 - 30, 2010, Steamboat, CO.

Technical Abstract: CGI-58 has been identified as the causative gene in the human neutral lipid storage disease called Chanarin-Dorfman Syndrome. This disorder results in accumulation of intracellular lipid droplets in non-adipose tissues. Here we show that disruption of the homologous CGI-58 gene in Arabidopsis thaliana results in abnormal accumulation of triacylglycerol (TAG)-containing neutral lipid droplets in leaves. On the other hand, TAG content of seeds was not altered in mutants. Mass spectroscopy of TAG isolated from leaves of cgi58 loss-of-function mutants showed they contain common leaf-specific fatty acids, containing 16:3 and no 20:1 acylgroups distinctly different from typical seed TAGs of Arabidopsis. Three-dimensional reconstructions of optical sections of cgi58 mutants by confocal laser scanning microscopy indicated that lipid droplets accumulated in the cytosol of mesophyll cells. Consistent with the extraplastidial lipid droplet location, CGI-58- GFP fusion proteins were localized to the cytosol in transient expression assays. In recent work by others, the recombinant CGI-58 protein from Arabidopsis expressed in E.coli had multiple enzymatic activities, including lysophosphatidic acid acyltranferase, phospholipase and TAG lipase (Ghosh et al., 2009, Plant Physiol 151:869). Taken together these results suggest that CGI-58 may normally regulate lipid turnover of TAG intermediates in vegetative cells and loss of this function results in cytosolic lipid droplet accumulation. We conclude that CGI-58 function in lipid homeostasis of non-fat storing tissues is generally conserved between plant and animal species. This may offer new possibilities for designing lipid rich compartments in vegetative tissues of crop plants.