PEX11β induces peroxisomal gene expression and alters peroxisome number during early Xenopus laevis development

Microinjecting haemagglutinin (HA) tagged Pex11β in early embryos resulted in increased RNA levels for peroxisome related genes PMP70 and catalase at developmental stages 10 and 20, versus uninjected embryos. Catalase and PMP70 proteins were found in punctate structures at stage 20 in control embryos, whereas the injection of ectopic HA-Pex11β induced their earlier localization in punctate structures at stage 10. Furthermore, the peroxisomal marker GFP-SKL, which was found localized as peroxisome-like structures at stage 20, was similarly found at stage 10 when co-microinjected with HA-Pex11β.Overexpressed Pex11β altered peroxisomal gene levels and induced the early formation of peroxisomes-like structures during development, both of which demonstrate that Pex11β may be a key regulator of peroxisome number in early Xenopus embryos.Peroxisomes are single-membrane bound organelles found ubiquitously in eukaryotic cells. They house more than 50 matrix enzymes that participate in a diverse array of metabolic processes including the β-oxidation of very long chain fatty acids (VLCFA) and α-oxidation of long branched-chain fatty acids [1]. Peroxisomes also contain oxidases that produce the corrosive byproduct hydrogen peroxide (H2O2) [2]. H2O2 and other dangerous reactive oxygen species (ROS) are then converted to innocuous products such as water and molecular oxygen by catalase and other enzymes within the peroxisome and in other cellular compartments [3]. Because of their complex roles in both cellular metabolism and ROS elimination, peroxisome function is strongly related to cellular development and eventual cellular senescence when their functionality begins to fail.While cellular aging and senescence are well characterized by peroxisomal dysfunction [4], little is known about the origin of these organelles, particularly during embryonic development. Important players in the regulation of overall peroxisome numbers are the peroxisome proliferator-activated receptors (P