Association of Fructosamine Levels with Glycemic Control in Children with Type 1 Diabetes as Determined by Continuous Glucose Monitoring: Results from the CGM TIME Trial.

OBJECTIVES: To determine the correlation between fructosamine, used to assess glycemia when HbA1c is not appropriate, with average blood glucose as measured by continuous glucose monitoring (CGM) in children with type 1 diabetes. METHODS: 97 blood samples were collected from 70 participants in the CGM TIME Trial. Each eligible participant had 3 weeks of CGM data with at least 60% CGM adherence prior to blood collection. Ordinary least squares linear regression incorporating restricted cubic splines was used to determine association between fructosamine and mean blood glucose. RESULTS: An association was found between fructosamine levels and mean blood glucose with F-statistic of 9.543 p-value <0.001). Data were used to create formulae and a conversion chart for calculating mean blood glucose from fructosamine levels for clinical use. CONCLUSIONS: There is a complex relationship between average blood glucose and fructosamine.

Implementation of the Mind Youth Questionnaire (MY-Q) for routine health-related quality of life screening of adolescents with type 1 diabetes in a large tertiary care center.

OBJECTIVES: Prevalence of diabetes distress and mental health comorbidities among adolescents with type 1 diabetes (T1D) is high. Despite recommendations for routine psychosocial risk assessment, there is little guidance for their implementation. This study aims to describe the implementation and baseline outcomes of the Mind Youth Questionnaire (MY-Q), a validated psychosocial screening tool for health-related quality of life (QoL) including mood, among adolescents living with T1D. METHODS: Adolescents aged 13-18 years completed the MY-Q from October 1, 2019-April 1, 2023. Baseline characteristics, MY-Q results including categories flagged positive (noting possible areas of concern), debrief duration, and frequency of social work or mental health referral were collected and analyzed using descriptive statistics. RESULTS: A total of 343 adolescents (mean age 15.3 years; 52 % female) completed a baseline MY-Q. Median overall MY-Q debrief time (IQR) was 10.0 min (6.0, 20.0). About 290 (84.5 %) adolescents had at least one of seven categories flagged, most commonly "Family" (61 %). About 30 % of adolescents had "Mood" flagged, and 2.9 % of adolescents were referred to mental health following debrief. CONCLUSIONS: Without the need for additional resources, implementation of the MY-Q in a pediatric tertiary care diabetes clinic successfully identified QoL issues and mental health concerns among adolescents with T1D.

cGAS Mediates the Inflammatory Responses of Human Microglial Cells to Genotoxic DNA Damage.

Genomic instability is a key driving force for the development and progression of many age-related neurodegenerative diseases and central nervous system (CNS) cancers. Recently, the cytosolic DNA sensor, cyclic GMP-AMP synthase (cGAS), has been shown to detect and respond to self-DNA accumulation resulting from DNA damaging insults in peripheral cell types. cGAS has been shown to be important in the responses of microglia to DNA viruses and amyloid beta, and we have reported that it underlies the responses of human microglia to exogenous DNA. However, the role of this cytosolic sensor in the detection of self-DNA by glia is poorly understood and its ability to mediate the cellular responses of human microglia to genotoxic DNA damage has not been established. Here, we describe the ability of ionizing radiation and oxidative stress to elicit genomic DNA damage in human microglial cells and to stimulate the production of key inflammatory mediators by these cells in an NF-kB dependent manner. Importantly, we have utilized CRISPR/Cas9 and siRNA-mediated knockdown approaches and a pharmacological inhibitor of the cGAS adaptor protein stimulator of interferon genes (STING) to demonstrate that the cGAS-STING pathway plays a critical role in the generation of these microglial immune responses to such genotoxic insults. Together, these studies support the notion that cGAS mediates the detection of cytosolic self-DNA by microglia, providing a potential mechanism linking genomic instability to the development of CNS cancers and neurodegenerative disorders.

Implementation and evaluation of a longitudinal diabetes educational programme for adolescents.

INTRODUCTION: International guidelines recommend structured and continuous educational programmes to expand diabetes knowledge and self-efficacy in youth. To address these recommendations within a paediatric diabetes clinic, we conducted a three-phase quality improvement project aimed at improving adolescents' confidence in diabetes self-management skills. METHODS: In phase 1, the Diabetes Learning Centre (DLC), an educational programme for adolescents with type 1 diabetes (T1D) ages 13-17 years, was developed and implemented. Programme feasibility was evaluated through programme attendance rates. Phase 2 aimed to guide ongoing programme development and optimisation. DLC attendees rated their baseline confidence in overall and individual T1D self-management skills on a 5-point Likert scale. Patient characteristics were summarised using descriptive statistics and the association between patient characteristics and overall confidence in T1D self-management was evaluated. Phase 3 used patient surveys to evaluate patient satisfaction and reported change in confidence in self-management skills following DLC attendance. RESULTS: In phase 1, 232 (81%) of eligible adolescents attended the DLC during the study period. In phase 2, median overall confidence in diabetes management on a Likert scale (0-4) was 3, representing 'quite confident', although confidence was low in some essential self-management skills. Higher confidence was associated with lower HbA1c (p<0.001). In phase 3, 77 (85%) of participants reported high levels of satisfaction with the DLC. 106 (82%) of completed worksheets were associated with improved confidence in the diabetes self-management skill addressed. CONCLUSIONS: Implementation of a longitudinal T1D educational model was feasible with good uptake in an existing T1D programme. While confidence at baseline was quite high for overall T1D self-management, it was low in some essential self-management skills, highlighting the need for this programme and specific educational gaps. Adolescents reported improvements in confidence and high levels of satisfaction following DLC attendance. Our model provides a replicable programme template to address longitudinal education needs.

An Intervention of Four Weeks of Time-Restricted Eating (16/8) in Male Long-Distance Runners Does Not Affect Cardiometabolic Risk Factors.

Timing of nutrient intake for athletes may affect exercise performance and cardiometabolic factors. Our objective was to examine the effect of time-restricted eating (TRE) on cardiometabolic health. Using a cross-over study design, 15 endurance-trained male runners were randomized to either a normal dietary pattern (ND) first (12 h eating/fasting times) followed by time-restricted eating (TRE) pattern (16 h fast; 8 h eating) or the reverse, with a 4-week washout period between interventions. Body composition, resting energy expenditure, blood pressure and serum insulin, glucose and lipids were measured using standard laboratory methods. Exercise training and dietary intake (calories and macronutrients) were similar across interventions. No significant differences were observed in resting energy expenditure, markers of insulin resistance, serum lipids or blood pressure. Body composition did change significantly (p < 0.05) with whole body fat mass (-0.8 ± 1.3 kg with TRE vs. +0.1 ± 4.3 kg with ND), leg fat mass (-0.3 ± 0.5 kg with TRE vs. +0.1 ± 0.4 kg with ND), and percent body fat (-1.0 ± 1.5% with TRE vs. +0.1 ± 1.3% with ND) declining more in the TRE intervention, with no change in fat-free mass. This study is one of a few to investigate the effects of an isocaloric 16/8 TRE eating pattern in trained endurance athletes and confirms no change in cardiometabolic risk factors. In conclusion, TRE is not detrimental to cardiometabolic health in endurance-trained male runners but could be beneficial on exercise performance by reducing fat mass.

Satiety Associated with Calorie Restriction and Time-Restricted Feeding: Peripheral Hormones.

Calorie restriction (CR) is a common approach to inducing negative energy balance. Recently, time-restricted feeding (TRF), which involves consuming food within specific time windows during a 24-h day, has become popular owing to its relative ease of practice and potential to aid in achieving and maintaining a negative energy balance. TRF can be implemented intentionally with CR, or TRF might induce CR simply because of the time restriction. This review focuses on summarizing our current knowledge on how TRF and continuous CR affect gut peptides that influence satiety. Based on peer-reviewed studies, in response to CR there is an increase in the orexigenic hormone ghrelin and a reduction in fasting leptin and insulin. There is likely a reduction in glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and cholecystokinin (CCK), albeit the evidence for this is weak. After TRF, unlike CR, fasting ghrelin decreased in some TRF studies, whereas it showed no change in several others. Further, a reduction in fasting leptin, insulin, and GLP-1 has been observed. In conclusion, when other determinants of food intake are held equal, the peripheral satiety systems appear to be somewhat similarly affected by CR and TRF with regard to leptin, insulin, and GLP-1. But unlike CR, TRF did not appear to robustly increase ghrelin, suggesting different influences on appetite with a potential decrease of hunger after TRF when compared with CR. However, there are several established and novel gut peptides that have not been measured within the context of CR and TRF, and studies that have evaluated effects of TRF are often short-term, with nonuniform study designs and highly varying temporal eating patterns. More evidence and studies addressing these aspects are needed to draw definitive conclusions.

The Omega-3 Index Response to an 8 Week Randomized Intervention Containing Three Fatty Fish Meals Per Week Is Influenced by Adiposity in Overweight to Obese Women.

BACKGROUND: The Dietary Guidelines for Americans (DGA) recommends consuming ~225 g/wk of a variety of seafood providing >1.75 g/wk of long-chain omega-3 fatty acids to reduce cardiovascular disease risk, however individual responses to treatment vary. OBJECTIVE: This study had three main objectives. First, to determine if a DGA-conforming diet (DGAD), in comparison to a typical American diet (TAD), can increase the omega-3 index (OM3I), i.e., the red blood cell mol% of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA). Second, to identify factors explaining variability in the OM3I response to dietary treatment. Third to identify factors associated with the baseline OM3I. DESIGN: This is a secondary analysis of a randomized, double-blind 8 wk dietary intervention of overweight/obese women fed an 8d rotating TAD (n = 20) or DGAD (n = 22) registered at www.clinicaltrials.gov as NCT02298725. The DGAD-group consumed 240 g/wk of Atlantic farmed salmon and albacore tuna in three meals with an estimated EPA + DHA of 3.7 ± 0.6 g/wk. The TAD-group consumed ~160 g/wk of farmed white shrimp and a seafood salad containing imitation crab in three meal with an estimated EPA + DHA of 0.45 ± 0.05 g/wk. Habitual diet was determined at baseline, and body composition was determined at 0 and 8wks. Red blood cell fatty acids were measured at 0, 2 and 8 wk. RESULTS: At 8 wk, the TAD-group OM3I was unchanged (5.90 ± 1.35-5.80 ± 0.76%), while the DGAD-group OM3I increased (5.63 ± 1.27-7.33 ± 1.36%; p < 0.001). In the DGAD-group 9 of 22 participants achieved an OM3I >8%. Together, body composition and the baseline OM3I explained 83% of the response to treatment variability. Baseline OM3I (5.8 ± 1.3%; n = 42) was negatively correlated to the android fat mass (p = 0.0007) and positively correlated to the FFQ estimated habitual (EPA+DHA) when expressed as a ratio to total dietary fat (p = 0.006). CONCLUSIONS: An 8 wk TAD did not change the OM3I of ~6%, while a DGAD with 240 g/wk of salmon and albacore tuna increased the OM3I. Body fat distribution and basal omega-3 status are primary factors influencing the OM3I response to dietary intake in overweight/obese women.

Satiety Associated with Calorie Restriction and Time-Restricted Feeding: Central Neuroendocrine Integration.

This review focuses on summarizing current knowledge on how time-restricted feeding (TRF) and continuous caloric restriction (CR) affect central neuroendocrine systems involved in regulating satiety. Several interconnected regions of the hypothalamus, brainstem, and cortical areas of the brain are involved in the regulation of satiety. Following CR and TRF, the increase in hunger and reduction in satiety signals of the melanocortin system [neuropeptide Y (NPY), proopiomelanocortin (POMC), and agouti-related peptide (AgRP)] appear similar between CR and TRF protocols, as do the dopaminergic responses in the mesocorticolimbic circuit. However, ghrelin and leptin signaling via the melanocortin system appears to improve energy balance signals and reduce hyperphagia following TRF, which has not been reported in CR. In addition to satiety systems, CR and TRF also influence circadian rhythms. CR influences the suprachiasmatic nucleus (SCN) or the primary circadian clock as seen by increased clock gene expression. In contrast, TRF appears to affect both the SCN and the peripheral clocks, as seen by phasic changes in the non-SCN (potentially the elusive food entrainable oscillator) and metabolic clocks. The peripheral clocks are influenced by the primary circadian clock but are also entrained by food timing, sleep timing, and other lifestyle parameters, which can supersede the metabolic processes that are regulated by the primary circadian clock. Taken together, TRF influences hunger/satiety, energy balance systems, and circadian rhythms, suggesting a role for adherence to CR in the long run if implemented using the TRF approach. However, these suggestions are based on only a few studies, and future investigations that use standardized protocols for the evaluation of the effect of these diet patterns (time, duration, meal composition, sufficiently powered) are necessary to verify these preliminary observations.

Four Weeks of 16/8 Time Restrictive Feeding in Endurance Trained Male Runners Decreases Fat Mass, without Affecting Exercise Performance.

BACKGROUND: Time restricted Feeding (TRF) is a dietary pattern utilized by endurance athletes, but there is insufficient data regarding its effects on performance and metabolism in this population. The purpose of this investigation was to examine the effects of a 16/8 TRF dietary pattern on exercise performance in trained male endurance runners. METHODS: A 4-week randomized crossover intervention was used to compare an 8-h TRF to a 12-h normal diet (ND) feeding window. Exercise training and dietary intake were similar across interventions. Runners completed a dual-energy X-ray absorptiometry (DXA) scan to assess body composition, a graded treadmill running test to assess substrate utilization, and ran a 10 km time trial to assess performance. RESULTS: There was a significant decrease in fat mass in the TRF intervention (-0.8 ± 1.3 kg with TRF (p = 0.05), vs. +0.1 ± 4.3 kg with ND), with no significant change in fat-free mass. Exercise carbon dioxide production (VCO2) and blood lactate concentration were significantly lower with the TRF intervention (p ≤ 0.02). No significant changes were seen in exercise respiratory exchange ratio or 10 km time trial performance (-00:20 ± 3:34 min:s TRF vs. -00:36 ± 2:57 min:s ND). CONCLUSION: This investigation demonstrated that adherence to a 4-week 16/8 TRF dietary intervention decreased fat mass and maintained fat-free mass, while not affecting running performance, in trained male endurance runners.

Motivational Stage at Continuous Glucose Monitoring (CGM) Initiation in Pediatric Type 1 Diabetes Is Associated With Current Glycemic Control but Does Not Predict Future CGM Adherence or Glycemic Control.

OBJECTIVES: The Timing of Initiation of Continuous Glucose Monitoring in Established Pediatric Diabetes (CGM TIME) Trial is a multicenter, randomized controlled trial in children with type 1 diabetes, comparing simultaneous pump and CGM with CGM initiation 6 months later (Paradigm, Veo, Enlite Sensor, Medtronic Canada). This study addresses the ability of SOCRATES (Stages Of Change Readiness And Treatment Eagerness Scale) to classify children and parents into distinct motivational stages and identify the stages' association with glycated hemoglobin (A1C) at trial entry and outcomes 6 months after CGM initiation. METHODS: Ninety-eight of 99 eligible children 10 to 18 years of age and 137 of 141 eligible parents completed SOCRATES at trial entry and 6 months later. Parent-child agreement for motivational stage was determined by weighted kappa. Linear regression was used to examine association between motivational stage and i) A1C at trial entry and ii) change in A1C and CGM adherence 6 months after CGM initiation. RESULTS: More than 87% of children and 88% of parents were classified into distinct motivational stages, with weak parent-child agreement. At trial entry, motivational stage was associated with A1C, which was 1.02% higher for children in the Action stage than in the Precontemplation stage (p<0.0001). When compared with children of parents in Precontemplation, A1C for children of parents in the Maintenance and Action stages were 0.83% (p=0.02) and 0.36% (p=0.048) higher, respectively. Precontemplation was associated with shorter diabetes duration. Motivational stage at CGM initiation did not predict change in A1C or CGM adherence 6 months later. CONCLUSIONS: SOCRATES can categorize children with type 1 diabetes and their parents into motivational stages. Although motivational stage was associated with glycemic control at trial entry, it did not predict future diabetes-related behaviour or A1C.

BBLN-1 is essential for intermediate filament organization and apical membrane morphology.

Epithelial tubes are essential components of metazoan organ systems that control the flow of fluids and the exchange of materials between body compartments and the outside environment. The size and shape of the central lumen confer important characteristics to tubular organs and need to be carefully controlled. Here, we identify the small coiled-coil protein BBLN-1 as a regulator of lumen morphology in the C. elegans intestine. Loss of BBLN-1 causes the formation of bubble-shaped invaginations of the apical membrane into the cytoplasm of intestinal cells and abnormal aggregation of the subapical intermediate filament (IF) network. BBLN-1 interacts with IF proteins and localizes to the IF network in an IF-dependent manner. The appearance of invaginations is a result of the abnormal IF aggregation, indicating a direct role for the IF network in maintaining lumen homeostasis. Finally, we identify bublin (BBLN) as the mammalian ortholog of BBLN-1. When expressed in the C. elegans intestine, BBLN recapitulates the localization pattern of BBLN-1 and can compensate for the loss of BBLN-1 in early larvae. In mouse intestinal organoids, BBLN localizes subapically, together with the IF protein keratin 8. Our results therefore may have implications for understanding the role of IFs in regulating epithelial tube morphology in mammals.

Timing of CGM initiation in pediatric diabetes: The CGM TIME Trial.

OBJECTIVE: To determine whether timing of CGM initiation offering low glucose suspend (LGS) affects CGM adherence in children and youth starting insulin pump therapy. METHODS: A 5-site RCT of pump-naïve subjects (aged 5-18 years) with type 1 diabetes (T1D) for at least 1 year compared simultaneous pump and CGM initiation offering LGS vs standard pump therapy with CGM initiation delayed for 6 months. Primary outcome was CGM adherence (hours per 28 days) (MiniMed™ Paradigm™ Veo™ system; CareLink Pro™ software) over 6 months after CGM initiation. Secondary outcome HbA1c was measured centrally. Linear mixed-models and ordinary least squares models were fitted to estimate effect of intervention, and covariates baseline age, T1D duration, HbA1c, gender, ethnicity, hypoglycemia history, clinical site, and association between CGM adherence and HbA1c. RESULTS: The trial randomized 144/152 (95%) eligible subjects. Baseline mean age was 11.5 ± 3.3(SD) years, T1D duration 3.4 ± 3.1 years, and HbA1c 7.9 ± 0.9%. Six months after CGM initiation, adjusted mean difference in CGM adherence was 62.4 hours per 28 days greater in the Simultaneous Group compared to Delayed Group (P = .007). There was no difference in mean HbA1c at 6 months. However, for each 100 hours of CGM use per 28-day period, HbA1c was 0.39% (95% CI 0.10%-0.69%) lower. Higher CGM adherence was associated with reduced time with glucose >10 mmol/L (P < .001). CONCLUSION: CGM adherence was higher after 6 months when initiated at same time as pump therapy compared to starting CGM 6 months after pump therapy. Greater CGM adherence was associated with improved HbA1c.

Fear of hypoglycemia in children with type 1 diabetes and their parents: Effect of pump therapy and continuous glucose monitoring with option of low glucose suspend in the CGM TIME trial.

To determine if pump therapy with continuous glucose monitoring offering low glucose suspend (LGS) decreases fear of hypoglycemia among children with type 1 diabetes and their parents. The CGM TIME trial is a multicenter randomized controlled trial that enrolled 144 children with type 1 diabetes for at least 1 year (mean duration 3.4 ± 3.1 years) starting pump therapy (MiniMed™ Veo™, Medtronic Canada). CGM (MiniMed™ Enlite™ sensor) offering LGS was introduced simultaneously or delayed for 6 months. Hypoglycemia Fear Scale (HFS) was completed by children ≥10 years old and all parents, at study entry and 12 months later. Simultaneous and Delayed Group participants were combined for all analyses. Subscale scores were compared with paired t-tests, and individual items with paired Wilcoxon tests. Linear regression examined association with CGM adherence. 121/140 parents and 91/99 children ≥10 years had complete data. Mean Behavior subscale score decreased from 21.1 (SD 5.9) to 17.2 (SD 6.1) (p < .001) for children, and 20.7 (SD 7.5) to 17.4 (7.4) (p < .001) for parents. Mean Worry subscale score decreased from 17.9 (SD 11.9) to 11.9 (SD 11.4) (p < .001) for children, and 23.1 (SD 13.2) to 17.6 (SD 10.4) (p < .001) for parents. Median scores for 10/25 child items and 12/25 parent items were significantly lower at 12 months (p < .001). Linear regression found no association between HFS scores and CGM adherence. Insulin pump therapy with CGM offering LGS significantly reduced fear of hypoglycemia not related to CGM adherence in children with type 1 diabetes and their parents.

Intestinal intermediate filament polypeptides in C. elegans: Common and isotype-specific contributions to intestinal ultrastructure and function.

The abundance and diversity of intermediate filaments (IFs) in the C. elegans intestine indicate important contributions to intestinal function and organismal wellbeing. Fluorescent IF reporters localize below the actin-rich brush border and are highly enriched in the lumen-enveloping endotube, which is attached to the C. elegans apical junction. Mapping intestinal viscoelasticity by contact-free Brillouin microscopy reveals that the IF-rich endotube is positioned at the interface between the stiff brush border and soft cytoplasm suggesting a mechanical buffering function to deal with the frequent luminal distortions occurring during food intake and movement. In accordance, depletion of IFB-2, IFC-2 and IFD-2 leads to intestinal lumen dilation although depletion of IFC-1, IFD-1 and IFP-1 do not. Ultrastructural analyses of loss of function mutants further show that IFC-2 mutants have a rarefied endotube and IFB-2 mutants lack an endotube altogether. Remarkably, almost all IFB-2- and IFC-2-deficient animals develop to fertile adults. But developmental retardation, reduced brood size, altered survival and increased sensitivity to microbial toxin, osmotic and oxidative stress are seen in both mutants albeit to different degrees. Taken together, we propose that individual intestinal IF polypeptides contribute in different ways to endotube morphogenesis and cooperate to cope with changing environments.

Bioflavonoids cause DNA double-strand breaks and chromosomal translocations through topoisomerase II-dependent and -independent mechanisms.

Bioflavonoids have a similar chemical structure to etoposide, the well-characterized topoisomerase II (Top2) poison, and evidence shows that they also induce DNA double-strand breaks (DSBs) and promote genome rearrangements. The purpose of this study was to determine the kinetics of bioflavonoid-induced DSB appearance and repair, and their dependence on Top2. Cells were exposed to bioflavonoids individually or in combination in the presence or absence of the Top2 catalytic inhibitor dexrazoxane. The kinetics of appearance and repair of γH2AX foci were measured. In addition, the frequency of resultant MLL-AF9 breakpoint cluster region translocations was determined. Bioflavonoids readily induced the appearance of γH2AX foci, but bioflavonoid combinations did not act additively or synergistically to promote DSBs. Myricetin-induced DSBs were mostly reduced by dexrazoxane, while genistein and quercetin-induced DSBs were only partially, but significantly, reduced. By contrast, luteolin and kaempferol-induced DSBs increased with dexrazoxane pre-treatment. Sensitivity to Top2 inhibition correlated with a significant reduction of bioflavonoid-induced MLL-AF9 translocations. These data demonstrate that myricetin, genistein, and quercetin act most similar to etoposide although with varying Top2-dependence. By contrast, luteolin and kaempferol have distinct kinetics that are mostly Top2-independent. These findings have implications for understanding the mechanisms of bioflavonoid activity and the potential of individual bioflavonoids to promote chromosomal translocations. Further, they provide direct evidence that specific Top2 inhibitors or targeted drugs could be developed that possess less leukemic potential or suppress chromosomal translocations associated with therapy-related and infant leukemias.

APE1 senses DNA single-strand breaks for repair and signaling.

DNA single-strand breaks (SSBs) represent the most abundant type of DNA damage. Unrepaired SSBs impair DNA replication and transcription, leading to cancer and neurodegenerative disorders. Although PARP1 and XRCC1 are implicated in the SSB repair pathway, it remains unclear how SSB repair and SSB signaling pathways are coordinated and regulated. Using Xenopus egg extract and in vitro reconstitution systems, here we show that SSBs are first sensed by APE1 to initiate 3'-5' SSB end resection, followed by APE2 recruitment to continue SSB end resection. Notably, APE1's exonuclease activity is critical for SSB repair and SSB signaling pathways. An APE1 exonuclease-deficient mutant identified in somatic tissue from a cancer patient highlighted the significance of APE1 exonuclease activity in cancer etiology. In addition, APE1 interacts with APE2 and PCNA, although PCNA is dispensable for APE1's exonuclease activity. Taken together, we propose a two-step APE1/APE2-mediated mechanism for SSB end resection that couples DNA damage response with SSB repair in a eukaryotic system.

Plant AtEH/Pan1 proteins drive autophagosome formation at ER-PM contact sites with actin and endocytic machinery.

The Arabidopsis EH proteins (AtEH1/Pan1 and AtEH2/Pan1) are components of the endocytic TPLATE complex (TPC) which is essential for endocytosis. Both proteins are homologues of the yeast ARP2/3 complex activator, Pan1p. Here, we show that these proteins are also involved in actin cytoskeleton regulated autophagy. Both AtEH/Pan1 proteins localise to the plasma membrane and autophagosomes. Upon induction of autophagy, AtEH/Pan1 proteins recruit TPC and AP-2 subunits, clathrin, actin and ARP2/3 proteins to autophagosomes. Increased expression of AtEH/Pan1 proteins boosts autophagosome formation, suggesting independent and redundant pathways for actin-mediated autophagy in plants. Moreover, AtEHs/Pan1-regulated autophagosomes associate with ER-PM contact sites (EPCS) where AtEH1/Pan1 interacts with VAP27-1. Knock-down expression of either AtEH1/Pan1 or VAP27-1 makes plants more susceptible to nutrient depleted conditions, indicating that the autophagy pathway is perturbed. In conclusion, we identify the existence of an autophagy-dependent pathway in plants to degrade endocytic components, starting at the EPCS through the interaction among AtEH/Pan1, actin cytoskeleton and the EPCS resident protein VAP27-1.

Host Vesicle Fusion Protein VAPB Contributes to the Nuclear Egress Stage of Herpes Simplex Virus Type-1 (HSV-1) Replication.

The primary envelopment/de-envelopment of Herpes viruses during nuclear exit is poorly understood. In Herpes simplex virus type-1 (HSV-1), proteins pUL31 and pUL34 are critical, while pUS3 and some others contribute; however, efficient membrane fusion may require additional host proteins. We postulated that vesicle fusion proteins present in the nuclear envelope might facilitate primary envelopment and/or de-envelopment fusion with the outer nuclear membrane. Indeed, a subpopulation of vesicle-associated membrane protein-associated protein B (VAPB), a known vesicle trafficking protein, was present in the nuclear membrane co-locating with pUL34. VAPB knockdown significantly reduced both cell-associated and supernatant virus titers. Moreover, VAPB depletion reduced cytoplasmic accumulation of virus particles and increased levels of nuclear encapsidated viral DNA. These results suggest that VAPB is an important player in the exit of primary enveloped HSV-1 virions from the nucleus. Importantly, VAPB knockdown did not alter pUL34, calnexin or GM-130 localization during infection, arguing against an indirect effect of VAPB on cellular vesicles and trafficking. Immunogold-labelling electron microscopy confirmed VAPB presence in nuclear membranes and moreover associated with primary enveloped HSV-1 particles. These data suggest that VAPB could be a cellular component of a complex that facilitates UL31/UL34/US3-mediated HSV-1 nuclear egress.

The intestinal intermediate filament network responds to and protects against microbial insults and toxins.

The enrichment of intermediate filaments in the apical cytoplasm of intestinal cells is evolutionarily conserved, forming a sheath that is anchored to apical junctions and positioned below the microvillar brush border, which suggests a protective intracellular barrier function. To test this, we used Caenorhabditiselegans, the intestinal cells of which are endowed with a particularly dense intermediate filament-rich layer that is referred to as the endotube. We found alterations in endotube structure and intermediate filament expression upon infection with nematicidal B.thuringiensis or treatment with its major pore-forming toxin crystal protein Cry5B. Endotube impairment due to defined genetic mutations of intermediate filaments and their regulators results in increased Cry5B sensitivity as evidenced by elevated larval arrest, prolonged time of larval development and reduced survival. Phenotype severity reflects the extent of endotube alterations and correlates with reduced rescue upon toxin removal. The results provide in vivo evidence for a major protective role of a properly configured intermediate filament network as an intracellular barrier in intestinal cells. This notion is further supported by increased sensitivity of endotube mutants to oxidative and osmotic stress.