RT Journal Article SR Electronic T1 The mitochondrial Rho-GTPase, Miro, is resident at peroxisomes and regulates peroxisomal trafficking and morphology JF bioRxiv FD Cold Spring Harbor Laboratory SP 241208 DO 10.1101/241208 A1 Christian Covill-Cooke A1 Guillermo López-Doménech A1 Nicol Birsa A1 Josef T. Kittler YR 2017 UL http://biorxiv.org/content/early/2017/12/30/241208.abstract AB Peroxisomes are essential for a number of cellular functions, including reactive oxygen species metabolism, fatty acid β-oxidation and lipid biosynthesis. To ensure optimal functionality of peroxisome-dependent processes throughout the cell they must be trafficked; however, peroxisomal transport remains poorly characterised. Here we show that Miro1 and Miro2, outer mitochondrial membrane proteins essential for mitochondrial trafficking, are also localised to peroxisomes. Peroxisomal localisation of Miro1 is negatively regulated by its first GTPase domain and is mediated by an interaction through its transmembrane domain with the peroxisomal-membrane protein chaperone, Pex19. By using Miro1/2 double knockout mouse embryonic fibroblasts (MEFs) we find that the loss of Miro1/2 leads to a significant reduction in short-range microtubule-independent peroxisomal motility. Additionally, Miro regulates peroxisomal size and morphology. Our results contribute to the fundamental understanding of peroxisomal trafficking and morphology, supporting a complex crosstalk between peroxisomal and mitochondrial biology.