Small G proteins in peroxisome biogenesis: the potential involvement of ADP-ribosylation factor 6
1 Department of Molecular Cell Biology, Catholic University of Leuven, Herestraat 49, Leuven, Belgium
2 Institute for Anatomy and Cell Biology II, Justus-Liebig University, Aulweg 123, Giessen, Germany
3 Department of Physiological Chemistry, Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Ten-nohdai, Tsukuba, Japan
4 Department of Molecular Microbiology, VIB, Leuven, Belgium
5 Department of Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, Leuven, Belgium
BMC Cell Biology 2009, 10:58 doi:10.1186/1471-2121-10-58Published: 17 August 2009
Peroxisomes execute diverse and vital functions in virtually every eukaryote. New peroxisomes form by budding from pre-existing organelles or de novo by vesiculation of the ER. It has been suggested that ADP-ribosylation factors and COPI coatomer complexes are involved in these processes.
Here we show that all viable Saccharomyces cerevisiae strains deficient in one of the small GTPases which have an important role in the regulation of vesicular transport contain functional peroxisomes, and that the number of these organelles in oleate-grown cells is significantly upregulated in the arf1 and arf3 null strains compared to the wild-type strain. In addition, we provide evidence that a portion of endogenous Arf6, the mammalian orthologue of yeast Arf3, is associated with the cytoplasmic face of rat liver peroxisomes. Despite this, ablation of Arf6 did neither influence the regulation of peroxisome abundance nor affect the localization of peroxisomal proteins in cultured fetal hepatocytes. However, co-overexpression of wild-type, GTP hydrolysis-defective or (dominant-negative) GTP binding-defective forms of Arf1 and Arf6 caused mislocalization of newly-synthesized peroxisomal proteins and resulted in an alteration of peroxisome morphology.
These observations suggest that Arf6 is a key player in mammalian peroxisome biogenesis. In addition, they also lend strong support to and extend the concept that specific Arf isoform pairs may act in tandem to regulate exclusive trafficking pathways.