A combined approach of quantitative interaction proteomics and live-cell imaging reveals a regulatory role for endoplasmic reticulum (ER) reticulon homology proteins in peroxisome biogenesis.

Peroxisome biogenesis initiates at the endoplasmic reticulum (ER) and maturation allows for the formation of metabolically active organelles. Yet, peroxisomes can also multiply by growth and division. Several proteins, called peroxins, are known to participate in these processes but little is known about their organization to orchestrate peroxisome proliferation. Here, we demonstrate that regulation of peroxisome proliferation relies on the integrity of the tubular ER network. Using a dual track SILAC-based quantitative interaction proteomics approach, we established a comprehensive network of stable as well as transient interactions of the peroxin Pex30p, an integral membrane protein. Through association with merely ER resident proteins, in particular with proteins containing a reticulon homology domain, and with other peroxins, Pex30p designates peroxisome contact sites at ER subdomains. We show that Pex30p traffics through the ER and segregates in punctae to which peroxisomes specifically append, and we ascertain its transient interaction with all subunits of the COPI coatomer complex suggesting the involvement of a vesicle-mediated transport. We establish that the membrane protein Pex30p facilitates the connection of peroxisomes to the ER. Taken together, our data indicate that Pex30p-containing protein complexes act as focal points from which peroxisomes can form and that the tubular ER architecture organized by the reticulon homology proteins Rtn1p, Rtn2p and Yop1p controls this process.

Structural basis for competitive interactions of Pex14 with the import receptors Pex5 and Pex19.

Protein import into peroxisomes depends on a complex and dynamic network of protein-protein interactions. Pex14 is a central component of the peroxisomal import machinery and binds the soluble receptors Pex5 and Pex19, which have important function in the assembly of peroxisome matrix and membrane, respectively. We show that the N-terminal domain of Pex14, Pex14(N), adopts a three-helical fold. Pex5 and Pex19 ligand helices bind competitively to the same surface in Pex14(N) albeit with opposite directionality. The molecular recognition involves conserved aromatic side chains in the Pex5 WxxxF/Y motif and a newly identified F/YFxxxF sequence in Pex19. The Pex14-Pex5 complex structure reveals molecular details for a critical interaction in docking Pex5 to the peroxisomal membrane. We show that mutations of Pex14 residues located in the Pex5/Pex19 binding region disrupt Pex5 and/or Pex19 binding in vitro. The corresponding full-length Pex14 variants are impaired in peroxisomal membrane localisation in vivo, showing that the molecular interactions mediated by the N-terminal domain modulate peroxisomal targeting of Pex14.

PEX14 is required for microtubule-based peroxisome motility in human cells.

We have established a procedure for isolating native peroxisomal membrane protein complexes from cultured human cells. Protein-A-tagged peroxin 14 (PEX14), a central component of the peroxisomal protein translocation machinery was genomically expressed in Flp-In-293 cells and purified from digitonin-solubilized membranes. Size-exclusion chromatography revealed the existence of distinct multimeric PEX14 assemblies at the peroxisomal membrane. Using mass spectrometric analysis, almost all known human peroxins involved in protein import were identified as constituents of the PEX14 complexes. Unexpectedly, tubulin was discovered to be the major PEX14-associated protein, and direct binding of the proteins was demonstrated. Accordingly, peroxisomal remnants in PEX14-deficient cells have lost their ability to move along microtubules. In vivo and in vitro analyses indicate that the physical binding to tubulin is mediated by the conserved N-terminal domain of PEX14. Thus, human PEX14 is a multi-tasking protein that not only facilitates peroxisomal protein import but is also required for peroxisome motility by serving as membrane anchor for microtubules.

Establishing a business case for setting up early detection services for preventing psychosis.

Under standard care, psychotic disorders can have limited response to treatments, high rates of chronicity and disability, negative impacts on families, and wider social and economic costs. In an effort to improve early detection and care of individuals developing a psychotic illness, early intervention in psychosis services and early detection services have been set up in various countries since the 1980s. In April 2016, NHS England implemented a new 'access and waiting times' standard for early intervention in psychosis to extend the prevention of psychosis across England. Unfortunately, early intervention and early detection services are still not uniformly distributed in the UK, leaving gaps in service provision. The aim of this paper is to provide a business case model that can guide clinicians and services looking to set up or expand early detection services in their area. The paper also focuses on some existing models of care within the Pan-London Network for Psychosis Prevention teams.

Bacterial community composition of biological degreasing systems and health risk assessment for workers.

Biological degreasing system is a new technology based on the degradation capabilities of microorganisms to remove oil, grease, or lubricants from metal parts. No data is available about the potential biological health hazards in such system. Thus, a health risk assessment linked to the bacterial populations present in this new degreasing technology is, therefore, necessary for workers. We performed both cultural and molecular approaches in several biological degreasing systems for various industrial contexts to investigate the composition and dynamics of bacterial populations. These biological degreasing systems did not work with the original bacterial populations. Indeed, they were colonized by a defined and restricted group of bacteria. This group replaced the indigenous bacterial populations known for degrading complex substrates. Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa, and Pantoea agglomerans were important members of the microflora found in most of the biological degreasing systems. These bacteria might represent a potential health hazard for workers.

The big sell: Managing stigma and workplace discrimination following moderate to severe brain injury.

BACKGROUND: Misperceptions regarding persons with brain injuries (PWBI) can lead to stigmatization, workplace discrimination and, in turn, influence PWBIs full vocational integration. OBJECTIVE: In this study we explored how stigma may influence return-to-work processes, experiences of stigma and discrimination at the workplace for persons with (moderate to severe) brain injuries, and strategies that can be employed to manage disclosure. METHODS: Exploratory qualitative study; used in-depth interviews and an inductive thematic analytical approach in data analysis. Ten PWBI and five employment service providers participated. PWBI discussed their work experiences, relationships with supervisors and co-workers and experiences of stigma and/or discrimination at work. Employment service providers discussed their perceptions regarding PWBI's rights and abilities to work, reported incidents of workplace discrimination, and how issues related to stigma, discrimination and disclosure are managed. RESULTS: Three themes were identified: i) public, employer and provider knowledge about brain injury and beliefs about PWBI; ii) incidents of workplace discrimination; iii) disclosure. Misperceptions regarding PWBI persist amongst the public and employers. Incidents of workplace discrimination included social exclusion at the workplace, hiring discrimination, denial of promotion/demotion, harassment, and failure to provide reasonable accommodations. Disclosure decisions required careful consideration of PWBI needs, the type of information that should be shared, and the context in which that information is shared. CONCLUSIONS: Public understanding about PWBI remains limited. PWBI require further assistance to manage disclosure and incidents of workplace discrimination.