Ribosomal Research Articles

Definition and clinical management of haemodialysis central venous catheter local infections (exit site and tunnel infection): An international consensus assessment.

To evaluate the relevance of signs and symptoms for the clinical identification of ESI and TI in HD-CVC, by means of international expert consensus, and to reach a consensus on a definition and clinical management (CM) for these infections. A recent systematic review showed a high heterogeneity in the signs/symptoms used for determining exit site infection (ESI) and tunnel infection (TI) of haemodialysis central venous catheter (HD-CVC). A modified Delphi ranking process was carried out between November 2020 and March 2021, consisting of four rounds using an online questionnaire with a panel of 26 experts from 12 countries. Experts responded on the level of relevance for the identification of ESI and TI, based on a list of 22 signs/symptoms obtained from a previous systematic review, using a 4-point Likert-type scale. After reaching consensus on the signs/symptoms, they followed the same method to reach consensus on the CM. The STROBE Checklist was used to report this study. A high degree of consensus was reached to identify the presence of ESI based on nine signs/symptoms: presence of pain at the exit site (ES) during interdialysis period, with fever ≥38°C do not suspect other cause, local signs at the ES (inflammation, induration, swelling, hyperemia/erythema ≥2 cm from ES) and obvious abscess or purulent exudate at ES; and of TI. Likewise, 5 cm were agreed upon. This Delphi study provides international expert consensus definitions of ESI and TI in HD-CVC, laying the groundwork for the validation of an HD-CVC ES clinical assessment scale for early identification of ESI. In addition, this study provides a series of attitudes to consensual clinics regarding signs/symptoms of local infections in HD-CVC, which may be useful as expert opinion in clinical practice guidelines, when there is insufficient scientific evidence.

Control of CCR5 Cell-Surface Targeting by the PRAF2 Gatekeeper.

The cell-surface targeting of neo-synthesized G protein-coupled receptors (GPCRs) involves the recruitment of receptors into COPII vesicles budding at endoplasmic reticulum exit sites (ERESs). This process is regulated for some GPCRs by escort proteins, which facilitate their export, or by gatekeepers that retain the receptors in the ER. PRAF2, an ER-resident four trans- membrane domain protein with cytoplasmic extremities, operates as a gatekeeper for the GB1 protomer of the heterodimeric GABAB receptor, interacting with a tandem di-leucine/RXR retention motif in the carboxyterminal tail of GB1. PRAF2 was also reported to interact in a two-hybrid screen with a peptide corresponding to the carboxyterminal tail of the chemokine receptor CCR5 despite the absence of RXR motifs in its sequence. Using a bioluminescence resonance energy transfer (BRET)-based subcellular localization system, we found that PRAF2 inhibits, in a concentration-dependent manner, the plasma membrane export of CCR5. BRET-based proximity assays and Co-IP experiments demonstrated that PRAF2/CCR5 interaction does not require the presence of a receptor carboxyterminal tail and involves instead the transmembrane domains of both proteins. The mutation of the potential di-leucine/RXR motif contained in the third intracellular loop of CCR5 does not affect PRAF2-mediated retention. It instead impairs the cell-surface export of CCR5 by inhibiting CCR5's interaction with its private escort protein, CD4. PRAF2 and CD4 thus display opposite roles on the cell-surface export of CCR5, with PRAF2 inhibiting and CD4 promoting this process, likely operating at the level of CCR5 recruitment into COPII vesicles, which leave the ER.

Role of activation signatures in re-entrant ventricular tachycardia circuits.

Development of a rapid means to verify the ventricular tachycardia (VT) isthmus location from heart surface electrogram recordings would be a helpful tool for the electrophysiologist. Myocardial infarction was induced in 22 canines by left anterior descending coronary artery ligation under general anesthesia. After3-5 days, VT was inducible via programmed electrical stimulation at the anterior left ventricular epicardial surface. Bipolar VT electrograms were acquired from 196 to 312 recording sites using a multielectrode array. Electrograms were marked for activation time, and activation maps were constructed. The activation signal, or signature, is defined as the cumulative number of recording sites that have activated per millisecond, and it was utilized to segment each circuit into inner and outer circuit pathways, and as an estimate of best ablation lesion location to prevent VT. VT circuit components were differentiable by activation signals as: inner pathway (mean: 0.30 sites activating/ms) and outer pathway (mean: 2.68 sites activating/ms). These variables were linearly related (p < .001). Activation signal characteristics were dependent in part upon the isthmus exit site. The inner circuit pathway determined by the activation signal overlappedand often extended beyondthe activation map isthmus location for each circuit. The best lesion location estimated by the activation signal would likely block an electrical impulse traveling through the isthmus, to prevent VT in all circuits. The activation signal algorithm, simple to implement for real-time computer display, approximates the VT isthmus location and shape as determined from activation marking, and best ablation lesion location to prevent reinduction.

How is polyadenylation restricted to 3'-untranslated regions?

Polyadenylation occurs at numerous sites within 3'-untranslated regions (3'-UTRs) but rarely within coding regions. How does Pol II travel through long coding regions without generating poly(A) sites, yet then permits promiscuous polyadenylation once it reaches the 3'-UTR? The cleavage/polyadenylation (CpA) machinery preferentially associates with 3'-UTRs, but it is unknown how its recruitment is restricted to 3'-UTRs during Pol II elongation. Unlike coding regions, 3'-UTRs have long AT-rich stretches of DNA that may be important for restricting polyadenylation to 3'-UTRs. Recognition of the 3'-UTR could occur at the DNA (AT-rich), RNA (AU-rich), or RNA:DNA hybrid (rU:dA- and/or rA:dT-rich) level. Based on the nucleic acid critical for 3'-UTR recognition, there are three classes of models, not mutually exclusive, for how the CpA machinery is selectively recruited to 3'-UTRs, thereby restricting where polyadenylation occurs: (1) RNA-based models suggest that the CpA complex directly (or indirectly through one or more intermediary proteins) binds long AU-rich stretches that are exposed after Pol II passes through these regions. (2) DNA-based models suggest that the AT-rich sequence affects nucleosome depletion or the elongating Pol II machinery, resulting in dissociation of some elongation factors and subsequent recruitment of the CpA machinery. (3) RNA:DNA hybrid models suggest that preferential destabilization of the Pol II elongation complex at rU:dA- and/or rA:dT-rich duplexes bridging the nucleotide addition and RNA exit sites permits preferential association of the CpA machinery with 3'-UTRs. Experiments to provide evidence for one or more of these models are suggested.

ALS/FTD-associated mutation in cyclin F inhibits ER-Golgi trafficking, inducing ER stress, ERAD and Golgi fragmentation

Amyotrophic lateral sclerosis (ALS) is a severely debilitating neurodegenerative condition that is part of the same disease spectrum as frontotemporal dementia (FTD). Mutations in the CCNF gene, encoding cyclin F, are present in both sporadic and familial ALS and FTD. However, the pathophysiological mechanisms underlying neurodegeneration remain unclear. Proper functioning of the endoplasmic reticulum (ER) and Golgi apparatus compartments is essential for normal physiological activities and to maintain cellular viability. Here, we demonstrate that ALS/FTD-associated variant cyclin FS621G inhibits secretory protein transport from the ER to Golgi apparatus, by a mechanism involving dysregulation of COPII vesicles at ER exit sites. Consistent with this finding, cyclin FS621G also induces fragmentation of the Golgi apparatus and activates ER stress, ER-associated degradation, and apoptosis. Induction of Golgi fragmentation and ER stress were confirmed with a second ALS/FTD variant cyclin FS195R, and in cortical primary neurons. Hence, this study provides novel insights into pathogenic mechanisms associated with ALS/FTD-variant cyclin F, involving perturbations to both secretory protein trafficking and ER-Golgi homeostasis.

Monitoring the Intracellular Trafficking of Virus-Induced Structures and Intercellular Spread of Viral Infection in Plants Using Endomembrane Trafficking Pathway-Specific Chemical Inhibitor and Organelle-Selective Fluorescence Dye.

Infection by positive-strand RNA viruses induces extensive remodeling of the host endomembrane system in favor of viral replication and movement. The integral membrane protein 6K2 of potyviruses induces the formation of membranous virus replication vesicles at the endoplasmic reticulum exit site (ERES). The intracellular trafficking of 6K2-induced vesicles along with microfilaments requires the vesicular transport pathway, actomyosin motility system, and possibly post-Golgi compartments such as endosomes as well. Recent studies have shown that endocytosis is essential for the intracellular movement of potyviruses from the site of viral genome replication/assembly site to plasmodesmata (PD) to enter neighboring cells. In this chapter, we describe a detailed protocol of how to use endomembrane trafficking pathway-specific chemical inhibitors and organelle-selective fluorescence dye to study the trafficking of potyviral proteins and potyvirus-induced vesicles and to unravel the role of endocytosis and the endocytic pathway in potyvirus infection in Nicotiana benthamiana plants.

Binding of small molecule inhibitors to RNA polymerase-Spt5 complex impacts RNA and DNA stability

Spt5 is an elongation factor that associates with RNA polymerase II (Pol II) during transcription and has important functions in promoter-proximal pausing and elongation processivity. Spt5 was also recognized for its roles in the transcription of expanded-repeat genes that are related to neurodegenerative diseases. Recently, a set of Spt5-Pol II small molecule inhibitors (SPIs) were reported, which selectively inhibit mutant huntingtin gene transcription. Inhibition mechanisms as well as interaction sites of these SPIs with Pol II and Spt5 are not entirely known. In this study, we predicted the binding sites of three selected SPIs at the Pol II-Spt5 interface by docking and molecular dynamics simulations. Two molecules out of three demonstrated strong binding with Spt5 and Pol II, while the other molecule was more loosely bound and sampled multiple binding sites. Strongly bound SPIs indirectly affected RNA and DNA dynamics at the exit site as DNA became more flexible while RNA was stabilized by increased interactions with Spt5. Our results suggest that the transcription inhibition mechanism induced by SPIs can be related to Spt5-nucleic acid interactions, which were altered to some extent with strong binding of SPIs.

Improving Quality Care and Patient Safety With Implementation of an Oversew Stitch in Lumbar Drains.

The lumbar drain exit site purse string oversew stitch is a well-described bedside intervention to stop or prevent cerebrospinal fluid (CSF) leak. It is not routinely placed at the time of lumbar drain placement. Via four plan-do-study-act (PDSA) cycles, we test the effect of prophylactic utilization of the lumbar drain exit site oversew stitch on house officers' paging burden, need to redress the drain, need to oversew the drain to stop a CSF leak, and need to replace the drain. We found that the simple act of placing an oversew stitch at the time of lumbar drain placement significantly reduced paging burden and reduced the frequency at which an oversew stitch was required to stop a CSF leak. Subjectively, during PDSA cycles during which overstitches were placed prophylactically, in-house residents perceived that there were less lumbar drains on service, although objectively, the overall number was unchanged. We conclude that prophylactic lumbar drain exit site stitch placement reduces risk and bedside interventions for patients and also reduces overall call burden on house officers. This simple intervention may therefore provide a more widespread improvement in care quality beyond lumbar drain care because house officers experience less burnout during their call shifts.

ATG9A regulates the dissociation of recycling endosomes from microtubules to form liquid influenza A virus inclusions.

It is now established that many viruses that threaten public health establish condensates via phase transitions to complete their lifecycles, and knowledge on such processes may offer new strategies for antiviral therapy. In the case of influenza A virus (IAV), liquid condensates known as viral inclusions, concentrate the 8 distinct viral ribonucleoproteins (vRNPs) that form IAV genome and are viewed as sites dedicated to the assembly of the 8-partite genomic complex. Despite not being delimited by host membranes, IAV liquid inclusions accumulate host membranes inside as a result of vRNP binding to the recycling endocytic marker Rab11a, a driver of the biogenesis of these structures. We lack molecular understanding on how Rab11a-recycling endosomes condensate specifically near the endoplasmic reticulum (ER) exit sites upon IAV infection. We show here that liquid viral inclusions interact with the ER to fuse, divide, and slide. We uncover that, contrary to previous indications, the reported reduction in recycling endocytic activity is a regulated process rather than a competition for cellular resources involving a novel role for the host factor ATG9A. In infection, ATG9A mediates the removal of Rab11a-recycling endosomes carrying vRNPs from microtubules. We observe that the recycling endocytic usage of microtubules is rescued when ATG9A is depleted, which prevents condensation of Rab11a endosomes near the ER. The failure to produce viral inclusions accumulates vRNPs in the cytosol and reduces genome assembly and the release of infectious virions. We propose that the ER supports the dynamics of liquid IAV inclusions, with ATG9A facilitating their formation. This work advances our understanding on how epidemic and pandemic influenza genomes are formed. It also reveals the plasticity of recycling endosomes to undergo condensation in response to infection, disclosing new roles for ATG9A beyond its classical involvement in autophagy.

Steady-state regulation of COPII-dependent secretory cargo sorting by inositol trisphosphate receptors, calcium, and penta EF hand proteins

Recently, we demonstrated that agonist-stimulated Ca2+ signaling involving IP3 receptors modulates ER export rates through activation of the penta-EF Hand proteins apoptosis-linked gene-2 (ALG-2) and peflin. It is unknown, however, whether IP3Rs and penta-EF proteins regulate ER export rates at steady state. Here we tested this idea in normal rat kidney epithelial cells by manipulation of IP3R isoform expression. Under standard growth conditions, spontaneous cytosolic Ca2+ oscillations occurred simultaneously in successive groups of contiguous cells, generating intercellular Ca2+ waves that moved across the monolayer periodically. Depletion of IP3R-3, typically the least promiscuous IP3R isoform, caused increased cell participation in intercellular Ca2+ waves in unstimulated cells. The increased spontaneous signaling was sufficient to cause increased ALG-2 and COPII coat subunit Sec31A and decreased peflin localization at ER exit sites, resulting in increased ER-to-Golgi transport of the COPII client cargo VSV-G. The elevated ER-to-Golgi transport caused greater concentration of VSV-G at ER exit sites and had reciprocal effects on transport of VSV-G and a bulk-flow cargo, though both cargos equally required Sec31A. Inactivation of client cargo sorting using 4-phenylbutyrate had opposing reciprocal effects on client and bulk-flow cargo and neutralized any effect of ALG-2 activation on transport. This work extends our knowledge of ALG-2 mechanisms and indicates that in normal rat kidney cells, IP3R isoforms regulate homeostatic Ca2+ signaling that helps determine the basal secretion rate and stringency of COPII-dependent cargo sorting.

Multi-center, pragmatic, cluster-randomized, controlled trial of standardized peritoneal dialysis (PD) training versus usual care on PD-related infections (the TEACH-PD trial): trial protocol

BackgroundPeritoneal dialysis (PD)-related infections, such as peritonitis, exit site, and tunnel infections, substantially impair the sustainability of PD. Accordingly, PD-related infection is the top-priority research outcome for patients and caregivers. While PD nurse trainers teach patients to perform their own PD, PD training curricula are not standardized or informed by an evidentiary base and may offer a potential approach to prevent PD infections. The Targeted Education ApproaCH to improve Peritoneal Dialysis outcomes (TEACH-PD) trial evaluates whether a standardized training curriculum for PD nurse trainers and incident PD patients based on the International Society for Peritoneal Dialysis (ISPD) guidelines reduces PD-related infections compared to usual training practices.MethodsThe TEACH-PD trial is a registry-based, pragmatic, open-label, multi-center, binational, cluster-randomized controlled trial. TEACH-PD will recruit adults aged 18 years or older who have not previously undergone PD training at 42 PD treatment units (clusters) in Australia and New Zealand (ANZ) between July 2019 and June 2023. Clusters will be randomized 1:1 to standardized TEACH-PD training curriculum or usual training practice. The primary trial outcome is the time to the first occurrence of any PD-related infection (exit site infection, tunnel infection, or peritonitis). The secondary trial outcomes are the individual components of the primary outcome, infection-associated catheter removal, transfer to hemodialysis (greater than 30 days and 180 days), quality of life, hospitalization, all-cause death, a composite of transfer to hemodialysis or all-cause death, and cost-effectiveness. Participants are followed for a minimum of 12 months with a targeted average follow-up period of 2 years. Participant and outcome data are collected from the ANZ Dialysis and Transplant Registry (ANZDATA) and the New Zealand Peritoneal Dialysis (NZPD) Registry. This protocol follows the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines.DiscussionTEACH-PD is a registry-based, cluster-randomized pragmatic trial that aims to provide high-certainty evidence about whether an ISPD guideline-informed standardized PD training curriculum for PD nurse trainers and adult patients prevents PD-related infections.Trial registrationClinicalTrials.gov NCT03816111. Registered on 24 January 2019.

18F-FDG PET/CT in left ventricular assist device infections: In-depth characterization and clinical implications

BackgroundPrevious retrospective studies suggest a good diagnostic performance of 18F-FDG-PET/CT in left ventricular assist device (LVAD) infections. Our aim was to prospectively evaluate the role of PET/CT in the characterization and impact on clinical management of LVAD infections. Methods40 patients (58[53–62] years) with suspected LVAD infection and 5 controls (69[64–71] years) underwent 18F-FDG-PET/CT. Four LVAD components were evaluated: exit site and subcutaneous driveline (peripheral), pump pocket, and outflow graft. The location with maximal uptake was considered the presumed site of infection. Infection was confirmed by positive culture (exit site or blood) and/or surgical findings. ResultsVisual uptake was present in 40 patients (100%) in the infection group vs 4 (80%) control subjects. For each individual component, presence of uptake was more frequent in the infection than in the control group. The location of maximal uptake was most frequently the pump pocket (48%) in the infection group and the peripheral components (75%) in the control group. SUVmax was higher in the infection than in the control group: SUVmax (average all components):6.9[5.1-8.5] vs 3.8[3.7-4.3], p=0.002; SUVmax (location of maximal uptake):10.6±4.0 vs 5.4±1.9, p=0.01.Pump pocket infections were more frequent in patients with bacteremia than without bacteremia (79% vs 31%, p=0.011). Pseudomonas (32%) and methicillin-susceptible Staphylococcus aureus (29%) were the most frequent pathogens and were associated with pump pocket infections, while Staphylococcus epidermis (11%) was associated with peripheral infections. PET/CT affected the clinical management of 83% of patients with infection, resulting in surgical debridement (8%), pump exchange (13%), and upgrade in the transplant listing status (10%) leading to 8% of urgent transplants. Conclusions18F-FDG-PET/CT enables the diagnosis and characterization of the extent of LVAD infections, which can significantly affect the clinical management of these patients.

Inpatient peritoneal dialysis catheters placed across the United States during a 3-year period: Lessons learned from 15,000 patients

BackgroundPeritoneal dialysis is a popular option for patients with end-stage renal disease. A recent presidential executive order has incentivized in-home end-stage renal disease treatments, leading to an increase in peritoneal dialysis use. Guidelines exist for creating and maintaining peritoneal dialysis access without addressing the optimal technique. This study evaluates nationwide peritoneal dialysis catheter placement practices and their long-term outcomes. MethodsRetrospective cohort analysis of Nationwide Readmission Database from 2017 to 2019. Patients with end-stage renal disease undergoing inpatient peritoneal dialysis catheter placement were included. Six-month readmissions, mortality, and peritoneal dialysis catheter-specific outcome measures were assessed among survivors of admission, including catheter leakage, mechanical breakdown, displacement, revision or replacement, removal, exit site infections, intra-abdominal abscess, and sepsis. Binary logistic regression analyses were performed. ResultsIn the study, 14,863 patients with inpatient peritoneal dialysis catheter insertions were identified, of which 7,096 were analyzed (4,150 [59%] laparoscopic, 1,781 [25%] fluoroscopic, 1,165 [16%] open), 847 (12%) had major complications, 931 (13%) were readmitted, and 102 (1.4%) died within 6 months. Univariate analyses demonstrated that laparoscopy had higher mechanical complications, exit-site infections, catheter revision, and removal within 6 months, and fluoroscopy had higher sepsis and mortality. Multivariate analyses showed fluoroscopy was associated with intraabdominal abscess (adjusted odds ratio, 2.36; P = .025), laparoscopy with exit-site infections (adjusted odds ratio, 0.49; P = .005), and open surgery with catheter displacement (adjust odds ratio, 2.95; P = .021). ConclusionThis is the first large-scale study on inpatient peritoneal dialysis catheter placement outcomes in the United States. Fluoroscopic and open surgical placements are routinely performed, but laparoscopy remains the mainstay with fewer exit-site infections. Overall, peritoneal dialysis is a safe option, with 1 in 9 patients having an infectious or mechanical complication within 6 months. Furthermore, large-scale prospective studies are warranted to identify the optimal placement technique.

Paradigm shift of catheter ablation of atypical atrioventricular nodal tachycardia: 3D mapping-based ablation of exits of slow pathway

Abstract Background In current practice, the ablation target of atypical atrioventricular nodal tachycardia (AVNRT) is the earliest atrial activation site in the coronary sinus (CS) or conventional slow pathway (SP) region. Objectives The purpose of this study was to map the site of earliest retrograde atrial activation using electroanatomic 3D mapping during atypical AVNRT and to evaluate successful ablation sites. Methods Forty-two patients with a total of 49 AVNRTs (slow/fast 30; fast/slow 15; slow/slow 4) underwent EP study and ablation. Among them there were 14 patients (10 women, 60±19 y/o) in whom 19 atypical AVNRT (fast/slow 15; slow/slow 4) were induced. Results The intracardiac electrocardiograms or 3D mapping of the exit site during tachycardia revealed that 7 patients had exit sites solely inside the CS (left inferior extension=LIE), 3 solely in the right postero-septal tricuspid annulus (TA) (right inferior extension=RIE), and 4 had both LIE and RIE exits. The distance from the CS ostium to LIE exits was 14±6 mm. RIE exits were located on the TA posterior to the CS ostium (between 5 and 6 o’clock in the LAO projection). Ablation targeting these exits or traditional SP succeeded in long term elimination of AVNRT in 13 of the 14 patients (93%). There were no complications. Conclusions Catheter ablation targeting the exit sites of LIE or RIE mapped at the CS or TA holds promise as an effective and safe alternative approach to the current targets of ablation for atypical AVNRT cases.Distribution of exit sites during atypicthe circuit of atypical AVNRT：the exit s

V-ATPase recruitment to ER exit sites switches COPII-mediated transport to lysosomal degradation

Endoplasmic reticulum (ER)-phagy is crucial to regulate the function and homeostasis of the ER via lysosomal degradation, but how it is initiated is unclear. Here we discover that Z-AAT, a disease-causing mutant of α1-antitrypsin, induces noncanonical ER-phagy at ER exit sites (ERESs). Accumulation of misfolded Z-AAT at the ERESs impairs coat protein complex II (COPII)-mediated ER-to-Golgi transport and retains V0 subunits that further assemble V-ATPase at the arrested ERESs. V-ATPase subsequently recruits ATG16L1 onto ERESs to mediate in situ lipidation of LC3C. FAM134B-II is then recruited by LC3C via its LIR motif and elicits ER-phagy leading to efficient lysosomal degradation of Z-AAT. Activation of this ER-phagy mediated by the V-ATPase-ATG16L1-LC3C axis (EVAC) is also triggered by blocking ER export. Our findings identify a pathway which switches COPII-mediated transport to lysosomal degradation for ER quality control.

Incidence of Fungal Peritonitis and Exit Site Infections Among Peritoneal Dialysis Patients in a Mid-Sized Dialysis Provider

Incidence of Fungal Peritonitis and Exit Site Infections Among Peritoneal Dialysis Patients in a Mid-Sized Dialysis Provider

Frequency of Catheter-Related Bacterial Infection in End Stage Renal Disease Patients on Hemodialysis

Objective: To determine the frequency of catheter related bacterial infections among the patients on hemodialysis due to end stage renal disease.&#x0D; Study Design: Cross sectional study&#x0D; Place and Duration of Study: Department of Nephrology, Sharif Medical City Hospital, Lahore Pakistan, from 6 Months i.e.,Jun 2021 to Oct 2021.&#x0D; Methodology: After meeting the inclusion and exclusion criteria 171 patients were enrolled. Tips of the catheters were removed by the surgeon and transferred to laboratory in a sterile container, while at least two blood culture samples were taken before removing the catheter. Catheter related bacterial infections were noted.&#x0D; Results: In this study the most common catheter related bacterial infection in ESRD cases on hemodialysis was blood stream tunnel infection noted in 48.5% patients followed by, infective endocarditis noted in 28.1%, echo vegetation in 26.3% patients, tunnel infection in 25.1% and exit site infection in 23.4% patients.&#x0D; Conclusion: The most common catheter related bacterial infection in ESRD cases on hemodialysis was blood stream tunnel infection followed by, infective endocarditis, echo vegetation, tunnel infection and exit site infection patients.

Intrinsically disordered region-mediated condensation of IFN-inducible SCOTIN/SHISA-5 inhibits ER-to-Golgi vesicle transport

Newly synthesized proteins in the endoplasmic reticulum (ER) are sorted by coat protein complex II (COPII) at the ER exit site en route to the Golgi. Under cellular stresses, COPII proteins become targets of regulation to control the transport. Here, we show that the COPII outer coat proteins Sec31 and Sec13 are selectively sequestered into the biomolecular condensate of SCOTIN/SHISA-5, which interferes with COPII vesicle formation and inhibits ER-to-Golgi transport. SCOTIN is an ER transmembrane protein with a cytosolic intrinsically disordered region (IDR), which is required and essential for the formation of condensates. Upon IFN-γ stimulation, which is a cellular condition that induces SCOTIN expression and condensation, ER-to-Golgi transport was inhibited in a SCOTIN-dependent manner. Furthermore, cancer-associated mutations of SCOTIN perturb its ability to form condensates and control transport. Together, we propose that SCOTIN impedes the ER-to-Golgi transport through its ability to form biomolecular condensates at the ER membrane.

A CYP78As-small grain4-coat protein complex Ⅱ pathway promotes grain size in rice.

CYP78A, a cytochrome P450 subfamily that includes rice (Oryza sativa L.) BIG GRAIN2 (BG2, CYP78A13) and Arabidopsis thaliana KLUH (KLU, CYP78A5), generate an unknown mobile growth signal (referred to as a CYP78A-derived signal) that increases grain (seed) size. However, the mechanism by which the CYP78A pathway increases grain size remains elusive. Here, we characterized a rice small grain mutant, small grain4 (smg4), with smaller grains than its wild type due to restricted cell expansion and cell proliferation in spikelet hulls. SMG4 encodes a multidrug and toxic compound extrusion (MATE) transporter. Loss of function of SMG4 causes smaller grains while overexpressing SMG4 results in larger grains. SMG4 is mainly localized to endoplasmic reticulum (ER) exit sites (ERESs) and partially localized to the ER and Golgi. Biochemically, SMG4 interacts with coat protein complex Ⅱ (COPⅡ) components (Sar1, Sec23, and Sec24) and CYP78As (BG2, GRAIN LENGTH 3.2 [GL3.2], and BG2-LIKE 1 [BG2L1]). Genetically, SMG4 acts, at least in part, in a common pathway with Sar1 and CYP78As to regulate grain size. In summary, our findings reveal a CYP78As-SMG4-COPⅡ regulatory pathway for grain size in rice, thus providing new insights into the molecular and genetic regulatory mechanism of grain size.

Compliance with good practice guidelines for the prevention of vascular access infections: the multi-centre PHYDEL survey in French haemodialysis units

French guidelines for the prevention of vascular access infections in a haemodialysis setting were released in 2005. Compliance with these guidelines is currently unknown. The aim of this study was to assess compliance with the guidelines for vascular access infection prevention in French haemodialysis units, and to describe the difficulties reported. A cross-sectional survey was conducted between March and December 2019 in 200 haemodialysis units in France, selected at random. Data were collected via questionnaire, completed by telephone interview with an infection control practitioner. A practice was deemed compliant when >85% of units declared that they always complied with the guidelines. In total, 103 units (51.5%) agreed to participate. Most practices complied with the guidelines; however, some practices did not reach the 85% compliance threshold for working in pairs when connecting central venous catheter (CVC) lines, performing hand hygiene before disconnecting lines, rinsing antiseptic soap before painting CVC exit site or arteriovenous fistula (AVF) puncture site, allowing antiseptic paint to dry, handling CVC branches with antiseptic impregnated gauze, performing hand hygiene after AVF compression with gloves, wearing protective eyewear when connecting/disconnecting CVC or when puncturing AVF, and wearing a gown when puncturing AVF. The most frequently reported difficulties were understaffing, difficulties with skin preparation because of exit site skin damage, and lack of buttonhole technical expertise. Despite good overall compliance, this survey highlights some shortcomings in compliance with infection prevention guidelines, which could be associated with either higher risk of vascular access infection or increased blood-borne virus transmission.