Current advances in the function and biogenesis of peroxisomes and their roles in health and disease.

The 7th Open European Peroxisome Meeting (OEPM) was held on the 15th and 16th of October 2020 due to the Corona pandemic as ZOOM conference. The OEPM is a biannual meeting organized by European expert researchers in peroxisome biology. Previous meetings were held in Leuven, Belgium (2006), Lunteren, The Netherlands (2010), Dijon, France (2012), Neuss, Germany (2014), Vienna, Austria (2016), and Groningen, The Netherlands (2018). For the 2020 meeting nearly 200 participants registered from 10 European countries, as well as Israel, Canada, the USA, Japan, Russia, and South Korea. At the OEPM, it is tradition that only young peroxisome researchers (PhD students or junior Post-docs) present their work to an international audience. At this year’s meeting, 46 talks were presented in eight sessions. During the meeting, the OEPM 2020 Peroxisome Research Young Investigator Award (sponsored by Ruhr-University of Bochum) was awarded. This award is given to the early career researcher, who was first author of the best publication in the peroxisome field over the last 2 years. At this meeting, the award was given to Victoria Riccio from the group of Peter Kim at the University of Toronto (Canada). The awarded paper describes that the deubiquitinating enzyme USP30 prevents pexophagy by counteracting the action of the peroxisomal E3 ubiquitin ligase PEX2. They also show that USP30 can rescue the peroxisome loss observed in some disease-causing peroxisome mutations, pointing to a potential therapeutic target (Riccio et al. 2019). Victoria Riccio received the prize during the meeting and presented the Young Investigator Award lecture about the paper. Members of the jury were Myriam Baes (Leuven), Mustapha Cherkaoui-Malki (Dijon), Ralf Erdmann (Bochum), Marc Fransen (Leuven), Aurora Pujol (Barcelona), Sigrun Reumann (Hamburg), Maya Schuldiner (Rehovot), Ron Wanders (Amsterdam), Bettina Warscheid (Freiburg), Hans Waterham (Amsterdam), and Einat Zalckvar (Rehovot). Iulia Revenco (KU Leuven, Belgium) and Marc Pilegaard Pedersen (University of Groningen, The Netherlands) presented the Marie Sklodowska-Curie Innovative European Training Network ‘PerICo’ (Peroxisome Interactions and Communication) that is coordinated by Prof. Dr. Ida van der Klei (University of Groningen). PerICo brings together ten full partners and five partner organizations, from seven European countries, together with Israel and Canada, and fosters the education of 15 PhD-students in projects aimed at uncovering how peroxisomes participate in cellular interactions and signaling. In the evening session, Andrew Longenecker presented ‘Diego’s story’, the case of his son Diego, who suffers from a PEX10 Zellweger Spectrum Disorder (ZSD), a peroxisome biogenesis disorder (PBD). In his presentation, he reported on a non-profit PBD-project (DiegoZSDResearch@gmail.com) that he and his wife created to engage with the research community and other parents. Peroxisomes are ubiquitous cell organelles of eukaryotic cells. They are surrounded by a single membrane and harbor a highly variable enzyme composition that determines the function of these multi-purpose organelles. Common functions of peroxisomes include β-oxidation of fatty acids and containment of pathways that produce hydrogen peroxide, which is then detoxified by catalase. Examples for species-specific peroxisomal pathways are alpha-oxidation of branched-chain fatty acids and synthesis of plasmalogens in humans, and contribution to the synthesis of penicillin in fungi or bile acids in humans (Wanders and Waterham 2006). Defects in peroxisomal enzymes or biogenesis of the organelle result in peroxisomal disorders, like X-linked Adrenoleukodystrophy or the Zellweger syndrome, respectively (Waterham et al. 2016). There is an increasing interest in peroxisome research, which is fueled by the fact that major questions concerning the biology of these fascinating organelles are still unanswered. Such as the import of folded, even oligomeric proteins into peroxisomes with the underlying mechanism still being unresolved (Baker et al. 2016; Walter and Erdmann 2019). Our knowledge on the biogenesis, dynamics (fission, transport), degradation by autophagy (pexophagy), etc. is still scarce, leaving room for exciting discoveries (Costello and Schrader 2018; Islinger et al. 2018; Mast et al. 2020; Mahalingam et al. 2020). Moreover, peroxisomes function in concert with other organelles, including metabolic interaction and signal transduction. In this context, an emerging theme is the investigation of physical contacts of peroxisomes and mitochondria, lipid droplets, vacuoles (lysosomes), and the ER via contact sites (Shai et al. 2016; Islinger et al. 2018; Farre et al. 2019; Schrader et al. 2020). Moreover, glycosomes, as peroxisomes of trypanosomatid parasites are called (due to the localization of glycolytic enzymes) have been identified as suitable targets for novel leads compounds for therapy of diseases like African sleeping sickness, Chagas Disease and Leishmaniasis (Dawidowski et al. 2017). Another reason for the steadily increasing interest is the perception that the cellular duties of these fascinating organelles go well beyond their undoubted metabolic functions. Peroxisomes turned out to have important non-metabolic roles, such as their function as signaling platform in antiviral response and thus their contribution to innate immunity (Ferreira et al. 2019), and their contribution to cooperative cell defense mechanisms against oxidative stress (Fujiki et al. 2020). Moreover, peroxisomes are critical contributors to ageing, longevity (Deori et al. 2018) and age-related disorders, including Alzheimer’s disease and cancer (Berger et al. 2016; Islinger et al. 2018; Dahabieh et al. 2018). Below is an overview of the sessions and talks of this very successful and inspiring OEPM. The order of talks at the meeting were essentially ordered alphabetically.