Cargo-Selected Transport from the Mitochondria to Peroxisomes Is Mediated by Vesicular Carriers

Abstract

Mitochondria and peroxisomes share a number of common biochemical processes, including the beta oxidation of fatty acids and the scavenging of peroxides. Here, we identify a new outer-membrane mitochondria-anchored protein ligase (MAPL) containing a really interesting new gene (RING)-finger domain. Overexpression of MAPL leads to mitochondrial fragmentation, indicating a regulatory function controlling mitochondrial morphology. In addition, confocal- and electron-microscopy studies of MAPL-YFP led to the observation that MAPL is also incorporated within unique, DRP1-independent, 70-100 nm diameter mitochondria-derived vesicles (MDVs). Importantly, vesicles containing MAPL exclude another outer-membrane marker, TOM20, and vesicles containing TOM20 exclude MAPL, indicating that MDVs selectively incorporate their cargo. We further demonstrate that MAPL-containing vesicles fuse with a subset of peroxisomes, marking the first evidence for a direct relationship between these two functionally related organelles. In contrast, a distinct vesicle population labeled with TOM20 does not fuse with peroxisomes, indicating that the incorporation of specific cargo is a primary determinant of MDV fate. These data are the first to identify MAPL, describe and characterize MDVs, and define a new intracellular transport route between mitochondria and peroxisomes.

The role of intracellular calcium phosphate in osteoblast-mediated bone apatite formation

“…Although the unregulated disruption of the mitochondrial membrane is ordinarily implicated in cell death and apoptosis, there is increasing evidence that regulated vesicular transport may occur between mitochondria and other cellular organelles. For example, iron may be transported to the mitochondria via endosomes (32), and more recent studies have shown that membranous vesicles bud off from mitochondria, transporting fatty acids to the peroxisome (33). The data presented here suggest a role for mitochondria in the trafficking of ions or clusters of calcium and phosphate ions to the extracellular space, facilitating mammalian mineralization.…”

E3 ubiquitin ligase SP1 regulates peroxisome biogenesis in Arabidopsis

“…S6 and Dataset S1). Human MAPL is localized to both mitochondria and peroxisomes, but its function in peroxisomes is unclear (57). It is possible that this family of E3 enzymes targets to and regulates the biogenesis of multiple organelles across diverse species.…”

Localization of mRNAs coding for peroxisomal proteins in the yeast, Saccharomyces cerevisiae

“…The large number of cells having POX1 mRNA localized to mitochondria might stem from the fact that Oxa1-RFP-labeled mitochondria fill a substantial volume of the cell. Alternatively, evidence for cargo-selective transport between mitochondria and peroxisomes has been reported (20), indicating that these organelles are in close contact. Thus, mPPs may appear juxtaposed to mitochondria, without necessarily being associated with the mitochondrial membrane.…”