Abstract
Bax inhibitor-1 (BI-1) is an endoplasmic reticulum-localized cell death suppressor widely conserved in animals and plants. Our recent studies have revealed that Arabidopsis BI-1 (AtBI-1) interacts with sphingolipid-metabolic enzymes, leading us to further analyses to elucidate roles of BI-1-modulated sphingolipids on cell death regulation. Sphingolipids are well-known to play an important role for formation of liquid-ordered membrane microdomain in plants as well as animals. Here we show compositional alterations of plasma membrane microdomain in AtBI-1 overexpressing rice cells. Glycosphingolipid composition in plasma membrane microdomain was elevated in AtBI-1 overexpressor. Furthermore, shotgun proteomics combined with label-free comparative analysis revealed significant decreases of microdomain-localized proteins possible to participate in cell death regulation, such as hypersensitive cell death-associated proteins and scaffolds for protein complexes in microdomain. Based on these results, we will discuss functional roles of microdomain remodeling in the cell death regulatory mechanism of BI-1.
