The polarity protein Yurt associates with the plasma membrane via basic and hydrophobic motifs embedded in its FERM domain.

The subcellular distribution of the polarity protein Yurt (Yrt) is subjected to a spatio-temporal regulation in Drosophila melanogaster embryonic epithelia. After cellularization, Yrt binds to the lateral membrane of ectodermal cells and maintains this localization throughout embryogenesis. During terminal differentiation of the epidermis, Yrt accumulates at septate junctions and is also recruited to the apical domain. Although the mechanisms through which Yrt associates with septate junctions and the apical domain have been deciphered, how Yrt binds to the lateral membrane remains as an outstanding puzzle. Here, we show that the FERM domain of Yrt is necessary and sufficient for membrane localization. Our data also establish that the FERM domain of Yrt directly binds negatively charged phospholipids. Moreover, we demonstrate that positively charged amino acid motifs embedded within the FERM domain mediates Yrt membrane association. Finally, we provide evidence suggesting that Yrt membrane association is functionally important. Overall, our study highlights the molecular basis of how Yrt associates with the lateral membrane during the developmental time window where it is required for segregation of lateral and apical domains.

Chlorhexidine plus alcohol versus povidone iodine plus alcohol, combined or not with innovative devices, for prevention of short-term peripheral venous catheter infection and failure (CLEAN 3 study): an investigator-initiated, open-label, single centre, randomised-controlled, two-by-two factorial trial.

BACKGROUND: Two billion peripheral venous catheters are sold globally each year, but the optimal skin disinfection and types of devices are not well established. We aimed to show the superiority of disinfection with 2% chlorhexidine plus alcohol over 5% povidone iodine plus alcohol in preventing infectious complications, and of closed integrated catheters, positive displacement needleless-connectors, disinfecting caps, and single-use prefilled flush syringes used in combination (innovation group) over open catheters and three-way stopcocks for treatment administration (standard group) in preventing catheter failure. METHODS: We did an open-label, randomised-controlled trial with a two-by-two factorial design, for which we enrolled adults (age ≥18 years) visiting the emergency department at the Poitiers University Hospital, France, and requiring one peripheral venous catheter before admission to the medical wards. Before catheter insertion, patients were randomly assigned (1:1:1:1) using a secure web-based random-number generator to one of four treatment groups based on skin preparation and type of devices (innovative devices or standard devices; 2% chlorhexidine plus alcohol or 5% povidone iodine plus alcohol). Primary outcomes were the incidence of infectious complications (local infection, catheter colonisation, or bloodstream infections) and time between catheter insertion and catheter failure (occlusion, dislodgment, infiltration, phlebitis, or infection). This study is registered with ClinicalTrials.gov, NCT03757143. FINDINGS: 1000 patients were recruited between Jan 7, and Sept 6, 2019, of whom 500 were assigned to the chlorhexidine plus alcohol group and 500 to the povidone iodine plus alcohol group (250 with innovative solutions and 250 with standard devices in each antiseptic group). No significant interaction was found between the two study interventions. Local infections occurred less frequently with chlorhexidine plus alcohol than with povidone iodine plus alcohol (0 [0%] of 496 patients vs six [1%] of 493 patients) and the same was observed for catheter colonisation (4/431 [1%] vs 70/415 [17%] catheters among the catheters cultured; adjusted subdistribution hazard ratio 0·08 [95% CI 0·02-0·18]). Median time between catheter insertion and catheter failure was longer in the innovation group compared with the standard group (50·4 [IQR 29·6-69·4] h vs 30·0 [16·6-52·6] h; p=0·0017). Minor skin reactions occurred in nine (2%) patients in the chlorhexidine plus alcohol group and seven (1%) patients in the povidone iodine plus alcohol group. INTERPRETATION: For skin antisepsis, chlorhexidine plus alcohol provides greater protection of peripheral venous catheter-related infectious complications than does povidone iodine plus alcohol. Use of innovative devices extends the catheter complication-free dwell time. FUNDING: Becton Dickinson.

Oligomerization of the FERM-FA protein Yurt controls epithelial cell polarity.

Drosophila melanogaster Yurt (Yrt) and its mammalian orthologue EPB41L5 limit apical membrane growth in polarized epithelia. EPB41L5 also supports epithelial-mesenchymal transition and metastasis. Yrt and EPB41L5 contain a four-point-one, ezrin, radixin, and moesin (FERM) domain and a FERM-adjacent (FA) domain. The former contributes to the quaternary structure of 50 human proteins, whereas the latter defines a subfamily of 14 human FERM proteins and fulfills unknown roles. In this study, we show that both Yrt and EPB41L5 oligomerize. Our data also establish that the FERM-FA unit forms an oligomeric interface and that multimerization of Yrt is crucial for its function in epithelial cell polarity regulation. Finally, we demonstrate that aPKC destabilizes the Yrt oligomer to repress its functions, thereby revealing a mechanism through which this kinase supports apical domain formation. Overall, our study highlights a conserved biochemical property of fly and human Yrt proteins, describes a novel function of the FA domain, and further characterizes the molecular mechanisms sustaining epithelial cell polarity.