CHD2 Regulates Neuron-glioma Interactions in Pediatric Glioma

High-grade gliomas (HGG) are deadly diseases for both adult and pediatric patients. Recently, it has been shown that neuronal activity promotes progression of multiple subgroups of HGG. However, epigenetic mechanisms that govern this process remain elusive. Here we report that the chromatin remodeler CHD2 regulates neuron-glioma interactions in diffuse midline glioma (DMG) characterized by onco-histone H3.1K27M. Depletion of CHD2 in H3.1K27M DMG cells compromises cell viability and neuron-to-glioma synaptic connections in vitro, neuron-induced proliferation of H3.1K27M DMG cells in vitro and in vivo, activity-dependent calcium transients in vivo, and extends the survival of H3.1K27M DMG-bearing mice. Mechanistically, CHD2 coordinates with the transcription factor FOSL1 to control the expression of axon-guidance and synaptic genes in H3.1K27M DMG cells. Together, our study reveals a mechanism whereby CHD2 controls the intrinsic gene program of the H3.1K27M DMG subtype, which in turn regulates the tumor growth-promoting interactions of glioma cells with neurons.

Learning dynamic graph representations through timespan view contrasts

The rich information underlying graphs has inspired further investigation of unsupervised graph representation. Existing studies mainly depend on node features and topological properties within static graphs to create self-supervised signals, neglecting the temporal components carried by real-world graph data, such as timestamps of edges. To overcome this limitation, this paper explores how to model temporal evolution on dynamic graphs elegantly. Specifically, we introduce a new inductive bias, namely temporal translation invariance, which illustrates the tendency of the identical node to keep similar labels across different timespans. Based on this assumption, we develop a dynamic graph representation framework CLDG that encourages the node to maintain locally consistent temporal translation invariance through contrastive learning on different timespans. Except for standard CLDG which only considers explicit topological links, our further proposed CLDG＋＋additionally employs graph diffusion to uncover global contextual correlations between nodes, and designs a multi-scale contrastive learning objective composed of local-local, local-global, and global-global contrasts to enhance representation capabilities. Interestingly, by measuring the consistency between different timespans to shape anomaly indicators, CLDG and CLDG＋＋are seamlessly integrated with the task of spotting anomalies on dynamic graphs, which has broad applications in many high-impact domains, such as finance, cybersecurity, and healthcare. Experiments demonstrate that CLDG and CLDG＋＋both exhibit desirable performance in downstream tasks including node classification and dynamic graph anomaly detection. Moreover, CLDG significantly reduces time and space complexity by implicitly exploiting temporal cues instead of complicated sequence models. The code and data are available at https://github.com/yimingxu24/CLDG.

Coordination of histone chaperones for parental histone segregation and epigenetic inheritance

Chromatin-based epigenetic memory relies on the accurate distribution of parental histone H3-H4 tetramers to newly replicated DNA strands. Mcm2, a subunit of the replicative helicase, and Dpb3/4, subunits of DNA polymerase ε, govern parental histone H3-H4 deposition to the lagging and leading strands, respectively. However, their contribution to epigenetic inheritance remains controversial. Here, using fission yeast heterochromatin inheritance systems that eliminate interference from initiation pathways, we show that a Mcm2 histone binding mutation severely disrupts heterochromatin inheritance, while mutations in Dpb3/4 cause only moderate defects. Surprisingly, simultaneous mutations of Mcm2 and Dpb3/4 stabilize heterochromatin inheritance. eSPAN (enrichment and sequencing of protein-associated nascent DNA) analyses confirmed the conservation of Mcm2 and Dpb3/4 functions in parental histone H3-H4 segregation, with their combined absence showing a more symmetric distribution of parental histone H3-H4 than either single mutation alone. Furthermore, the FACT histone chaperone regulates parental histone transfer to both strands and collaborates with Mcm2 and Dpb3/4 to maintain parental histone H3-H4 density and faithful heterochromatin inheritance. These results underscore the importance of both symmetric distribution of parental histones and their density at daughter strands for epigenetic inheritance and unveil distinctive properties of parental histone chaperones during DNA replication.

Perioperative duloxetine improves postoperative outcomes after anterior talofibular ligament repair for chronic lateral ankle instability for patients with depression: A prospective randomized clinical trial

BACKGROUND

Recent studies have indicated that depression is associated with persistent postoperative pain and decreased satisfaction following foot and ankle surgery. This study aimed to evaluate the effect of perioperative duloxetine on postoperative outcomes of anterior talofibular ligament (ATFL) surgical repair for chronic ankle instability (CAI) in patients with depression. We further sought to evaluate patients' satisfaction and side effects related to duloxetine.

MATERIAL AND METHODS

Patients undergoing ATFL repair were screened for depression preoperatively with the Patient Health Questionnaire (PHQ-9). Among 249 patients who underwent arthroscopic or open surgical Brostrom repair of the ATFL, 120 patients were identified as being "possibly depressed" and were included in the study. Sixty patients were randomly assigned to the duloxetine group (one day preoperatively and for 6 weeks postoperatively), and the other sixty were randomized to the placebo group. Painkillers and opioid consumption, pain scores, and patient satisfaction were recorded at 12, 24, 48, and 72 hours postoperatively and at follow-up visits 1, 3, and 6 months after surgery. Patient-reported outcome measures (PROMs) were assessed preoperatively and at 3, 6, 12 and 24 months postoperatively. Duloxetine-related side effects such as nausea/vomiting and fatigue were also recorded.

RESULTS

The patients in the duloxetine group reported a significantly longer time to rescue analgesic and reduced opioid requirements (including celecoxib, pregabalin, acetaminophen, and tramadol). The patients experienced decreased pain intensity and greater satisfaction with their pain management at 24, 48, 72 h and 1 and 3 months after surgery (P < 0.05). The duloxetine group also had significantly better clinical and functional outcomes at 3 and 6 month follow-up compared to the placebo group (P < 0.05). The occurrence and rate of symptoms of duloxetine side effects was not significant.

DISCUSSION

Depression is an important factor to consider and address because its presence before surgery can predict poor postoperative outcomes, including more severe postoperative pain, persistent postoperative pain, and increased consumption of painkillers and opioids.

CONCLUSION

Perioperative administration of duloxetine following ATFL repair for CAI in patients with depression increased the time to first postoperative rescue analgesic request and reduced both opioid consumption and postoperative pain. This approach also led to a high level of patient satisfaction. In addition, duloxetine improved the quality of recovery without leading to significant side effects.

LEVEL OF EVIDENCE

I; prospective randomized controlled trial.

[Progress on microneedle drug delivery systems for the treatment of corneal diseases]

Corneal diseases are prevalent eye conditions in China, and the lack of effective treatment in the short term can lead to blindness. However, delivering drugs to the cornea safely and effectively poses a significant challenge due to the presence of ocular barriers and clearance mechanisms. Conventional drug delivery methods exhibit low bioavailability, making it difficult to achieve therapeutic effects. Microneedles, with their ability to penetrate ocular surface barriers effectively, offer a low-invasive and highly promising drug delivery technology. This article introduces the main delivery barriers on the ocular surface, classifies microneedles, and highlights the latest developments in the treatment of corneal diseases. Finally, the potential challenges of applying microneedle delivery systems to the ocular surface are analyzed, aiming to provide insights for the clinical application of microneedles in corneal diseases.

Association of Molecular Subtypes with Pathologic Response, PFS, and OS in a Phase II Study of COXEN with Neoadjuvant Chemotherapy for Muscle-invasive Bladder Cancer

PURPOSE

The Coexpression Extrapolation (COXEN) gene expression model with chemotherapy-specific scores [for methotrexate, vinblastine, adriamycin, cisplatin (ddMVAC) and gemcitabine/cisplatin (GC)] was developed to identify responders to neoadjuvant chemotherapy (NAC). We investigated RNA-based molecular subtypes as additional predictive biomarkers for NAC response, progression-free survival (PFS), and overall survival (OS) in patients treated in S1314.

EXPERIMENTAL DESIGN

A total of 237 patients were randomized between four cycles of ddMVAC (51%) and GC (49%). On the basis of Affymetrix transcriptomic data, we determined subtypes using three classifiers: TCGA (k = 5), Consensus (k = 6), and MD Anderson (MDA; k = 3) and assessed subtype association with path response to NAC and determined associations with COXEN. We also tested whether each classifier contributed additional predictive power when added to a model based on predefined stratification (strat) factors (PS 0 vs. 1; T2 vs. T3, T4a).

RESULTS

A total of 155 patients had gene expression results, received at least three of four cycles of NAC, and had pT-N response based on radical cystectomy. TCGA three-group classifier basal-squamous (BS)/neuronal, luminal (Lum), Lum infiltrated, and GC COXEN score yielded the largest AUCs for pT0 (0.59, P = 0.28; 0.60, P = 0.18, respectively). For downstaging (

CONCLUSIONS

The Consensus classifier, based in part on the TCGA and MDA classifiers, modestly improved prediction for pathologic downstaging but subtypes were not associated with PFS or OS.

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Key Words Collapse

MESH Headings

• Humans
• Cisplatin/therapeutic use
• Cystectomy/methods
• Deoxycytidine/therapeutic use
• Muscles/pathology
• Neoadjuvant Therapy/methods
• Neoplasm Invasiveness
• Progression-Free Survival
• Retrospective Studies
• Urinary Bladder Neoplasms/drug therapy
• Urinary Bladder Neoplasms/genetics
• Urinary Bladder Neoplasms/pathology

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Grants

• UG1 CA233320 NCI NIH HHS
• UG1 CA233324 NCI NIH HHS
• UG1 CA180830 NCI NIH HHS
• UG1 CA233160 NCI NIH HHS
• U10 CA032102 NCI NIH HHS
• UG1 CA233196 NCI NIH HHS
• U10 CA180888 NCI NIH HHS
• U24 CA114748 NCI NIH HHS
• U10 CA180819 NCI NIH HHS
• UG1 CA233328 NCI NIH HHS

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Asymmetric distribution of parental H3K9me3 in S phase silences L1 elements

In eukaryotes, repetitive DNA sequences are transcriptionally silenced through histone H3 lysine 9 trimethylation (H3K9me3). Loss of silencing of the repeat elements leads to genome instability and human diseases, including cancer and ageing1-3. Although the role of H3K9me3 in the establishment and maintenance of heterochromatin silencing has been extensively studied4-6, the pattern and mechanism that underlie the partitioning of parental H3K9me3 at replicating DNA strands are unknown. Here we report that H3K9me3 is preferentially transferred onto the leading strands of replication forks, which occurs predominantly at long interspersed nuclear element (LINE) retrotransposons (also known as LINE-1s or L1s) that are theoretically transcribed in the head-on direction with replication fork movement. Mechanistically, the human silencing hub (HUSH) complex interacts with the leading-strand DNA polymerase Pol ε and contributes to the asymmetric segregation of H3K9me3. Cells deficient in Pol ε subunits (POLE3 and POLE4) or the HUSH complex (MPP8 and TASOR) show compromised H3K9me3 asymmetry and increased LINE expression. Similar results were obtained in cells expressing a MPP8 mutant defective in H3K9me3 binding and in TASOR mutants with reduced interactions with Pol ε. These results reveal an unexpected mechanism whereby the HUSH complex functions with Pol ε to promote asymmetric H3K9me3 distribution at head-on LINEs to suppress their expression in S phase.

Prognostic Significance of the Novel Nutrition-Inflammation Marker of Lymphocyte-C-Reactive Protein Ratio in Patients with Nasopharyngeal Carcinoma Receiving Concurrent Chemoradiotherapy

PURPOSE/OBJECTIVE(S)

Recent studies indicate that the novel lymphocyte-C-reactive protein ratio (LCR) is strongly associated with the survival of various tumors, but its prognostic value in nasopharyngeal carcinoma (NPC) is understudied. This study aimed to explore the relationship between the LCR and overall survival (OS) in NPC and to develop a predictive model.

MATERIALS/METHODS

A total of 841 NPC patients received concurrent chemoradiotherapy (CCRT) were retrospectively enrolled and randomly divided into training cohort (n = 589) and validation cohort (n = 252). Univariate and multivariate Cox analyses were performed to identify variables associated with OS and construct a predictive nomogram. The predictive accuracy of the nomogram was evaluated and independently validated.

RESULTS

The LCR score differentiated NPC patients into two groups with distinct prognoses (HR = 0.53; 95% CI: 0.32-0.89, P = 0.014). Multivariate analysis showed that age, T stage, N stage, EBV-DNA status, and LCR score were independently associated with OS and a predictive nomogram was developed. The nomogram had a good performance for the prediction of OS [C-index = 0.770 (95% CI: 0.675-0.864)] and outperformed the traditional staging system [C-index = 0.589 (95% CI: 0.385-0.792)]. The results were internally validated using an independent cohort.

CONCLUSION

The novel nutrition-inflammation marker of LCR could serve as a simplified, affordable, easy-to-obtain, non-invasive, and readily promotive prognostic marker for NPC patients received CCRT, and the LCR-based prognostic nomogram outperformed the conventional staging system in terms of predictive power.

Anterior Cruciate Ligament Reconstruction Using Autologous Hamstrings Augmented with Ligament Augmentation and Reconstruction Systems (LARS) or Synthetic Meshwork of LARS Compared with Four-Strand Hamstring Tendon Grafts Alone, a Prospective, Randomized Clinical Study with 2- to 8-Year Follow-Up

Purpose

To compare the long-term outcomes of anterior cruciate ligament (ACL) reconstruction using a four-strand hamstring tendon graft alone (hamstring group) or with synthetics (Ligament Augmentation and Reconstruction System, LARS group) or synthetic meshwork of LARS (meshwork group).

Methods

Patients who underwent ACL reconstruction using four-strand hamstring tendon grafts (hamstring group), autologous hamstrings augmented with the LARS (LARS group), or synthetic meshwork of LARS (meshwork group) were selected in this prospective randomized clinical study. Patient-reported outcome measures (PROMs) were obtained preoperatively; at 6, 12, and 18 months postoperatively; and at final follow-up between 3 and 8 years. Second-look arthroscopic findings were used to evaluate graft morphology based on graft tension, graft tear, and synovial coverage.

Results

A total of 141 consecutive patients underwent ACL reconstruction, 47 patients in each group, and 21 patients were lost to follow-up during the study period. At the 6-month follow-up, the IKDC scores and Lysholm scores were significantly better in the LARS group (P < 0.05). At the 6- and 12-month follow-ups, the KOS-ADLS, KOOS-activities of daily living and quality of life, NSARS scores, GRC scores, Tegner scores, and ACL-RSI scores were significantly better in the LARS group (P < 0.05). For the LARS group, hamstring group, and meshwork group, the cumulative failure rates were 8.5%, 12.8%, and 4.3%, respectively. Malposition of the femoral tunnel was significantly associated with cumulative failure (P < 0.05). There was no difference between the groups in other outcomes at any other time, including radiographic and arthroscopic outcomes.

Conclusions

ACL reconstruction using autologous hamstring augmented with LARS resulted in significantly better clinical scores with a faster return to sports and comparative side-to-side differences in graft laxity by 6 and 12 months follow-up. Despite these findings, no statistically significant differences were seen among the three patient groups in terms of objective outcomes and clinical scores at the 18-month, 3-year and 8-year follow-ups. Additionally, a malpositioned femoral tunnel was associated with graft failure.

Uncovering the active constituents and mechanisms of Rujin Jiedu powder for ameliorating LPS-induced acute lung injury using network pharmacology and experimental investigations

Background: Acute lung injury (ALI) is a common clinical disease with high mortality. Rujin Jiedu powder (RJJD) has been clinically utilized for the treatment of ALI in China, but the active constituents in RJJD and its protective mechanisms against ALI are still unclear. Methodology: ALI mice were established by intraperitoneal injection of LPS to test the effectiveness of RJJD in treating ALI. Histopathologic analysis was used to assess the extent of lung injury. An MPO (myeloperoxidase) activity assay was used to evaluate neutrophil infiltration. Network pharmacology was used to explore the potential targets of RJJD against ALI. Immunohistochemistry and TUNEL staining were performed to detect apoptotic cells in lung tissues. RAW264.7 and BEAS-2B cells were used to explore the protective mechanisms of RJJD and its components on ALI in vitro. The inflammatory factors (TNF-α, IL-6, IL-1β and IL-18) in serum, BALF and cell supernatant were assayed using ELISA. Western blotting was performed to detect apoptosis-related markers in lung tissues and BEAS-2B cells. Results: RJJD ameliorated pathological injury and neutrophil infiltration in the lungs of ALI mice and decreased the levels of inflammatory factors in serum and BALF. Network pharmacology investigations suggested that RJJD treated ALI via regulating apoptotic signaling pathways, with AKT1 and CASP3 as crucial targets and PI3K-AKT signaling as the main pathway. Meanwhile, baicalein, daidzein, quercetin and luteolin were identified as key constituents in RJJD targeting on the above crucial targets. Experimental investigations showed that RJJD significantly upregulated the expression of p-PI3K, p-Akt and Bcl-2, downregulated the expression of Bax, caspase-3 and caspase-9 in ALI mice, and attenuated lung tissue apoptosis. Four active constituents in RJJD (baicalein, daidzein, quercetin and luteolin) inhibited the secretion of TNF-α and IL-6 in LPS-induced RAW264.7 cells. Among these components, daidzein and luteolin activated the PI3K-AKT pathway and downregulated the expression of apoptosis-related markers induced by LPS in BEAS-2B cells. Conclusion: RJJD alleviates the inflammatory storm and prevents apoptosis in the lungs of ALI mice. The mechanism of RJJD in treating ALI is related to the activation of PI3K-AKT signaling pathway. This study provides a scientific basis for the clinical application of RJJD.

Tourniquet Use Improves Intraoperative Parameters, Leading to Similar Postoperative Outcomes Compared With No Tourniquet Use in Anterior Cruciate Ligament Reconstruction: A Prospective, Double-Blind, Randomized Clinical Trial

PURPOSE

To examine the effect of tourniquet use in arthroscopic anterior cruciate ligament reconstruction in terms of: (1) intraoperative visualization with operative time and consumption of sterile saline, and (2) intra- and postoperative blood loss, postoperative pain, opioid consumption, swelling, serum creatine phosphokinase (CPK) and hemoglobin (Hb) concentrations, clinical outcomes, and graft healing.

METHODS

In this prospective randomized clinical trial, patients were assigned to tourniquet inflation (tourniquet-up) or tourniquet deflation (tourniquet-down) groups. Primary outcomes were intraoperative visualization with operative time and sterile saline consumption. Secondary outcomes were intra- and postoperative blood loss, postoperative pain, opioid consumption, swelling, serum CPK, Hb concentration, subjective and objective functional scores, and graft healing.

RESULTS

Intraoperative visualization was satisfactory in 100 of 100 cases in the tourniquet-up group and 64 of 100 cases in the tourniquet-down group (P < .05). The mean operative time was 58.4 ± 5.7 minutes in the tourniquet-up group and 72.5 ± 8.6 minutes in the tourniquet-down group (P < .05). The mean sterile saline consumption was 6.4 ± 2.5 L in the tourniquet-up group and 8.7 ± 4.6 L in the tourniquet-down group (P < .05). The respective amounts of estimated intraoperative and postoperative blood loss were 95.3 ± 25.1 mL and 240.3 ± 44.5 mL in the tourniquet-up group and 230.2 ± 22.3 mL and 75.6 ± 15.3 mL in the tourniquet-down group (P < .05). Our results showed no significant difference in postoperative pain, opioid consumption, percentage of patients using opioids, swelling, mean serum CPK and Hb levels, subjective and objective functional scores, or graft healing (P > .05) between the 2 groups.

CONCLUSIONS

Tourniquet use during anterior cruciate ligament reconstruction significantly improves intraoperative visualization, shortens operative time, and decreases intraoperative sterile saline consumption and blood loss without serious adverse events or greater complication rates based on early postoperative outcomes.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

Comparative investigation between raw and stir-frying processed Cuscutae Semen based on HPLC fingerprints coupled with chemometric methods

BACKGROUND

The curative effect of Cuscutae Semen could be adjusted after stir-frying, and it's difficult to distinguish between the raw Cuscutae Semen (CS) and stir-frying processed Cuscutae Semen (SFCS) in clinical practice.

OBJECTIVE

The paper aims to establish the fingerprints of raw and fried Cuscutae Semen products by high performance liquid chromatography (HPLC) so that could analyze the compounds in raw and stir fried products qualitatively and quantitatively. At the same time, the chemometrics method was used to evaluate the difference between CS and SFCS to provide reference for the research of traditional Chinese medicine Cuscutae Semen.

METHOD

The raw and stir-frying processed Cuscutae Semen products related substances were separated on C18 column (250 mm × 4.6 mm, 5 µm) maintained at 30 °C (column temperature). The mobile phase comprised 0.1% formic acid aqueous solution (A) and acetonitrile (B), and a detection wavelength of 328 nm. The datas were imported into statistical software for chemometric analysis.

RESULTS

The developed HPLC method exhibits good linearity and has good systematic applicability. The content of these 12 compounds in the samples was further determined and the data analysed by chemometrics. The results showed that the composition of CS changed on heating and HCA showed that CS and SFCS could be clearly distinguished. PCA showed that six components caused differences, namely neochlorogenic acid, cryptophyllogenic acid, caffeic acid, quercetin, isorhamnetin and kaempferol.

CONCLUSIONS

This study unequivocally establishes a chromatographic fingerprint method intended for the extensive analysis of raw and stir-frying processed CS, which could substantially enhance the quality control of Cuscutae Semen and the rational development and utilization of traditional Chinese medicine (TCMs) resources.

HIGHLIGHTS

This method for the simultaneous quantification of multiple compounds in CS and SFCS, and revealing the components responsible for the differences between raw and processed products. This will provide support for quality control of this herbal medicine.

Landscape of MicroRNA Regulatory Network Architecture and Functional Rerouting in Cancer

Somatic mutations are a major source of cancer development, and many driver mutations have been identified in protein coding regions. However, the function of mutations located in miRNA and their target binding sites throughout the human genome remains largely unknown. Here, we built detailed cancer-specific miRNA regulatory networks across 30 cancer types to systematically analyze the effect of mutations in miRNAs and their target sites in 3' untranslated region (3' UTR), coding sequence (CDS), and 5' UTR regions. A total of 3,518,261 mutations from 9,819 samples were mapped to miRNA-gene interactions (mGI). Mutations in miRNAs showed a mutually exclusive pattern with mutations in their target genes in almost all cancer types. A linear regression method identified 148 candidate driver mutations that can significantly perturb miRNA regulatory networks. Driver mutations in 3'UTRs played their roles by altering RNA binding energy and the expression of target genes. Finally, mutated driver gene targets in 3' UTRs were significantly downregulated in cancer and functioned as tumor suppressors during cancer progression, suggesting potential miRNA candidates with significant clinical implications. A user-friendly, open-access web portal (mGI-map) was developed to facilitate further use of this data resource. Together, these results will facilitate novel noncoding biomarker identification and therapeutic drug design targeting the miRNA regulatory networks.

SIGNIFICANCE

A detailed miRNA-gene interaction map reveals extensive miRNA-mediated gene regulatory networks with mutation-induced perturbations across multiple cancers, serving as a resource for noncoding biomarker discovery and drug development.

Epigenome Programming by H3.3K27M Mutation Creates a Dependence of Pediatric Glioma on SMARCA4

Patients with diffuse midline gliomas that are H3K27 altered (DMG) display a dismal prognosis. However, the molecular mechanisms underlying DMG tumorigenesis remain poorly defined. Here we show that SMARCA4, the catalytic subunit of the mammalian SWI/SNF chromatin remodeling complex, is essential for the proliferation, migration, and invasion of DMG cells and tumor growth in patient-derived DMG xenograft models. SMARCA4 colocalizes with SOX10 at gene regulatory elements to control the expression of genes involved in cell growth and the extracellular matrix (ECM). Moreover, SMARCA4 chromatin binding is reduced upon depletion of SOX10 or H3.3K27M, a mutation occurring in about 60% DMG tumors. Furthermore, the SMARCA4 occupancy at enhancers marked by both SOX10 and H3K27 acetylation is reduced the most upon depleting the H3.3K27M mutation. Taken together, our results support a model in which epigenome reprogramming by H3.3K27M creates a dependence on SMARCA4-mediated chromatin remodeling to drive gene expression and the pathogenesis of H3.3K27M DMG.

SIGNIFICANCE

DMG is a deadly pediatric glioma currently without effective treatments. We discovered that the chromatin remodeler SMARCA4 is essential for the proliferation of DMG with H3K27M mutation in vitro and in vivo, identifying a potentially novel therapeutic approach to this disease. See related commentary by Beytagh and Weiss, p. 2730. See related article by Panditharatna et al., p. 2880. This article is highlighted in the In This Issue feature, p. 2711.

Mcm2 promotes stem cell differentiation via its ability to bind H3-H4

Mcm2, a subunit of the Mcm2-7 helicase best known for its role in DNA replication, contains a histone binding motif that facilitates the transfer of parental histones following DNA replication. Here we show that Mcm2 is important for the differentiation of mouse embryonic stem (ES) cells. The Mcm2-2A mutation defective in histone binding shows defects in silencing of pluripotent genes and the induction of lineage specific genes. The defects in the induction of lineage specific genes in the mutant cells are likely, at least in part, due to reduced binding to Asf1a, a histone chaperone that binds Mcm2 and is important for nucleosome disassembly at bivalent chromatin domains containing repressive H3K27me3 and active H3K4me3 modifications during differentiation. Mcm2 localizes at transcription starting sites and the binding of Mcm2 at gene promoters is disrupted in both Mcm2-2A ES cells and neuro-precursor cells (NPCs). Reduced Mcm2 binding at bivalent chromatin domains in Mcm2-2A ES cells correlates with decreased chromatin accessibility at corresponding sites in NPCs. Together, our studies reveal a novel function of Mcm2 in ES cell differentiation, likely through manipulating chromatin landscapes at bivalent chromatin domains.

Generalized pulp canal obliteration in a patient on long-term glucocorticoids: a case report and literature review

BACKGROUND

The calcification of the tooth pulp is a pathological condition that occurs in response to various factors. A uncommon haematological condition known as paroxysmal nocturnal haemoglobinuria (PNH) is characterized by bouts of haemolysis, and it requires long-term use of glucocorticoids (GCs).

CASE PRESENTATION

A female patient who was diagnosed with PNH and had a history of long-term use of GCs came to our department for root canal therapy (RCT) for teeth 25, 26, and 27. The radiographs showed generalized pulp canal obliteration (PCO) in most of the patients. None of these teeth (25, 26, or 27) were sensitive to percussion, and they did not respond to thermal or electrical sensitivity tests. A diagnose of pulp necrosis was made for these teeth. RCT was carried out with the help of an oral microscope, and then a prosthodontic procedure was created for the teeth.

CONCLUSIONS

Based on the patient's long history use of GCs and a series of related studies, we conclude that the long-term usage of GCs contributes significantly to the onset of PCO.

Stable inheritance of H3.3-containing nucleosomes during mitotic cell divisions

Newly synthesized H3.1 and H3.3 histones are assembled into nucleosomes by different histone chaperones in replication-coupled and replication-independent pathways, respectively. However, it is not clear how parental H3.3 molecules are transferred following DNA replication, especially when compared to H3.1. Here, by monitoring parental H3.1- and H3.3-SNAP signals, we show that parental H3.3, like H3.1, are stably transferred into daughter cells. Moreover, Mcm2-Pola1 and Pole3-Pole4, two pathways involved in parental histone transfer based upon the analysis of modifications on parental histones, participate in the transfer of both H3.1 and H3.3 following DNA replication. Lastly, we found that Mcm2, Pole3 and Pole4 mutants defective in parental histone transfer show defects in chromosome segregation. These results indicate that in contrast to deposition of newly synthesized H3.1 and H3.3, transfer of parental H3.1 and H3.3 is mediated by these shared mechanisms, which contributes to epigenetic memory of gene expression and maintenance of genome stability.

How nucleosome assembly of parental histones is regulated following DNA replication is still an open question. Here the authors show that unlike deposition of new histones H3.1 and H3.3 that utilizes different histone chaperones, parental H3.1 and H3.3 are both stably inherited during mitotic cell division in mouse embryonic stem cells, and this involves histone chaperones Mcm2, Pole3 and Pole4.

Role of ANO1 in tumors and tumor immunity

Dysregulation of gene amplification, cell-signaling-pathway transduction, epigenetic and transcriptional regulation, and protein interactions drives tumor-cell proliferation and invasion, while ion channels also play an important role in the generation and development of tumor cells. Overexpression of Ca²⁺-activated Cl- channel anoctamin 1 (ANO1) is shown in numerous cancer types and correlates with poor prognosis. However, the mechanisms involved in ANO1-mediated malignant cellular transformation and the role of ANO1 in tumor immunity remain unknown. In this review, we discuss recent studies to determine the role of ANO1 in tumorigenesis and provide novel insights into the role of ANO1 in the context of tumor immunity. Furthermore, we analyze the roles and potential mechanisms of ANO1 in different types of cancers, and provide novel notions for the role of ANO1 in the tumor microenvironment and for potential use of ANO1 in clinical applications. Our review shows that ANO1 is involved in tumor immunity and microenvironment, and may, therefore, be an effective biomarker and therapeutic drug target.

Economic evaluations of interventions against influenza at workplaces: systematic review

BACKGROUND

The burden of influenza is mostly felt by employees and employers because of increased absenteeism rates, loss of productivity and associated direct costs. Even though interventions against influenza among working adults are effective, patronage and compliance to these measures especially vaccination are low compared to other risk groups.

AIMS

This study was aimed to assess evidence of economic evaluations of interventions against influenza virus infection among workers or in the workplace setting.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) reporting guideline for systematic reviews was followed. Three databases, PubMed, Web of Science and EconLit, were searched using keywords to identify relevant articles from inception till 25 October 2020. Original peer-reviewed papers that conducted economic evaluations of influenza interventions using cost-benefit, cost-effectiveness or cost-utility analysis methods focused on working-age adults or work settings were eligible for inclusion. Two independent teams of co-authors extracted and synthesized data from identified studies.

RESULTS

Twenty-four articles were included: 21 were cost-benefit analyses and 3 examined cost-effectiveness analyses. Two papers also presented additional cost-utility analysis. Most of the studies were pharmaceutical interventions (n = 23) primarily focused on vaccination programs while one study was a non-pharmaceutical intervention examining the benefit of paid sick leave. All but two studies reported that interventions against influenza virus infection at the workplace were cost-saving and cost-effective regardless of the analytic approach.

CONCLUSIONS

Further cost-effectiveness research in non-pharmaceutical interventions against influenza in workplace settings is warranted. There is a need to develop standardized methods for reporting economic evaluation methods to ensure comparability and applicability of future research findings.

Research on the dynamic hammering method for identifying weak parts in cantilever structures

Identification of the vulnerabilities in the structural stiffness is one of the most crucial issues in improving this property of machine tools. In this paper, the Flexibility Matrix Diagonal element method, based on hammer testing, is proposed as an effective approach to identifying the stiffness weakness of cantilever structures. To verify the proposed method, the element stiffness weakening is used to simulate the weak parts regarding stiffness. Several scenarios, with single and multiple weakness points, including various noise levels, are studied, using finite element simulations. Next, a novel method, to measure the accuracy of the algorithm and quantify the weakness level, under noise conditions, is proposed. The advantage of this method, compared to the ones based on Flexibility Difference Method, is the higher identification accuracy under noise interference. Finally, the cantilever beam with elastic support is experimentally studied. The natural frequencies and modal shapes are obtained, according to the singular value decomposition method, to establish the flexibility matrix. In addition, using only the lowest three modes, a series of numerical examples and experiments are provided, to illustrate the validity and the considerable practical engineering value of the method.

Efficient and strand-specific profiling of replicating chromatin with enrichment and sequencing of protein-associated nascent DNA in mammalian cells

Faithful duplication of both genetic and epigenetic information is essential for all eukaryotic cells. DNA replication initiates from replication origins and proceeds bidirectionally but asymmetrically, with the leading strand being synthesized continuously and the lagging strand discontinuously as Okazaki fragments by distinct DNA polymerases. Unraveling the underlying mechanisms of chromatin replication at both strands is crucial to better understand DNA replication and its coupled processes, including nucleosome assembly, sister chromatid cohesion and DNA mismatch repair. Here we describe the enrichment and sequencing of protein-associated nascent DNA (eSPAN) method to analyze the enrichment of proteins of interest, including histones and their modifications at replicating chromatin in a strand-specific manner in mammalian cells. Briefly, cells are pulsed with the thymidine analog bromodeoxyuridine to label newly synthesized DNA. After cell permeabilization, the target proteins are sequentially bound by antibodies and protein A-fused transposase, which digests and tags genomic DNA of interest once activated by magnesium. The strand specificity is preserved through oligo-replacement. Finally, the resulting double-strand DNA is denatured and immunoprecipitated with antibodies against bromodeoxyuridine to enrich nascent DNA associated with proteins of interest. After PCR amplification and next-generation sequencing, the mapped reads are used to calculate the relative enrichment of the target proteins around replication origins. Compared with alternative methods, the eSPAN protocol is simple, cost-effective and sensitive, even in a relatively small number of mammalian cells. The whole procedures from cell collection to generation of sequencing-ready libraries can be completed in 2 days.

mi-IsoNet: systems-scale microRNA landscape reveals rampant isoform-mediated gain of target interaction diversity and signaling specificity

MicroRNA (miRNA) is not a single sequence, but a series of multiple variants (also termed isomiRs) with sequence and expression heterogeneity. Whether and how these isoforms contribute to functional variation and complexity at the systems and network levels remain largely unknown. To explore this question systematically, we comprehensively analyzed the expression of small RNAs and their target sites to interrogate functional variations between novel isomiRs and their canonical miRNA sequences. Our analyses of the pan-cancer landscape of miRNA expression indicate that multiple isomiRs generated from the same miRNA locus often exhibit remarkable variation in their sequence, expression and function. We interrogated abundant and differentially expressed 5' isomiRs with novel seed sequences via seed shifting and identified many potential novel targets of these 5' isomiRs that would expand interaction capabilities between small RNAs and mRNAs, rewiring regulatory networks and increasing signaling circuit complexity. Further analyses revealed that some miRNA loci might generate diverse dominant isomiRs that often involved isomiRs with varied seeds and arm-switching, suggesting a selective advantage of multiple isomiRs in regulating gene expression. Finally, experimental validation indicated that isomiRs with shifted seed sequences could regulate novel target mRNAs and therefore contribute to regulatory network rewiring. Our analysis uncovers a widespread expansion of isomiR and mRNA interaction networks compared with those seen in canonical small RNA analysis; this expansion suggests global gene regulation network perturbations by alternative small RNA variants or isoforms. Taken together, the variations in isomiRs that occur during miRNA processing and maturation are likely to play a far more complex and plastic role in gene regulation than previously anticipated.

Research on the dynamic identification method of weak parts in cantilever structures

Determining the weak parts of a structure is one of the key issues in the field of machine tool stiffness improvement. However, studies show that overcoming the static deformation with acquisition difficulty is a complex problem in practical structures. This study considers the machine tool cantilever structure, as a cantilever beam and bar structure, where the objective is to propose a weakness index, to identify the weak part, using system reconstruction to extract the measured static deformation data and the fitting data. Stiffness reduction is used to simulate weak parts, while the effectiveness of the method is evaluated, in the case of various weakness values and of different noise levels, using the finite element simulation approach. The validity of the proposed method is illustrated through comparison of the theoretical results to the experimental ones, using the cantilever structure of a test machine tool. The research content provides some means of improving the machining accuracy of machine tools.

SHCBP1 Promotes the Progression of Esophageal Squamous Cell Carcinoma Via the TGFβ Pathway

Esophageal cancer (EC) is known as a type of common malignant tumor, with the incidence ranking eighth worldwide. Because of the high metastasis of advanced EC, the total survival rate has been quite low. Esophageal squamous cell carcinoma (ESCC) is a main type of EC. Targeted therapy for ESCC has become a new direction; however, newly therapeutic targets are also badly needed. Shc SH2 domain-binding protein (SHCBP1) is located on 16q11.2, which is a downstream protein of the Shc adaptor. SHCBP1 participates in the regulation of several physiological and pathologic processes, such as cytokinesis. Recent studies have found that SHCBP1 was abnormally upregulated in multiple types of tumors, such as breast cancer and liver cancer, and that it affects the proliferation and motility of cancer cells in vitro. However, it remains unclear whether SHCBP1 is related to the progression of EC. Herein, we found the upregulation of SHCBP1 in human EC tissues. Our findings further demonstrated that SHCBP1 expression was related to the clinical features of ESCC patients. We found that SHCBP1 depletion inhibited the proliferation and motility of ESCC cells via the transforming growth factor β pathway and that it suppressed the growth of tumors in mice. We, therefore, concluded that SHCBP1 could serve as a promising EC molecular target.

Prognostic model for risk stratification of de novo metastatic nasopharyngeal carcinoma patients treated with chemotherapy followed by locoregional radiotherapy

BACKGROUND

There is no clinically applicable prognostic model designed for patients with de novo metastatic nasopharyngeal carcinoma (mNPC) treated with chemotherapy followed by locoregional radiotherapy (LRRT). We sought to develop a predictive tool of overall survival for individualized prediction and risk stratification in this heterogeneous patient population.

PATIENTS AND METHODS

A total of 244 eligible patients with de novo mNPC, who were treated with platinum-based first-line chemotherapy followed by LRRT, were included in this retrospective study. We divided patients into the training and validation sets based on the date of initial treatment, with 152 patients treated between 2008 and 2013 comprising the training set for model development and 92 patients treated at a later time (2014 to 2015) forming the validation set. We applied Cox proportional hazards model to examine factors associated with overall survival (OS). We developed and subsequently validated a prognostic model to predict OS. We assessed the performance of this prognostic model and stratified patients based on prognostic scores obtained from this proposed model.

RESULTS

The median OS of the entire cohort was 60.9 months. C-creative protein, number of metastatic sites, liver metastasis, post-treatment Epstein-Barr virus DNA, and response of metastasis were significantly associated with OS. A prognostic model for individual survival prediction was developed and graphically represented as a nomogram. The model showed favorable discrimination (C-index: 0.759), predictive accuracy [time dependent area under the curve (tAUC) at 5 years: 0.800], and calibration, and was further validated in an independent dataset. A risk stratification derived from the model can stratify these patients into three prognostic subgroups with significantly different survival.

CONCLUSION

We developed and validated a prognostic model that exhibited adequate performance in individualized prediction and risk stratification for patients with de novo mNPC treated with chemotherapy followed by LRRT.

Exosomal miR-499a-5p Inhibits Endometrial Cancer Growth and Metastasis via Targeting VAV3

Background/Aim

The current therapeutic strategies for endometrial cancer are limited and unsatisfactory. Accumulating evidence suggest that microRNAs (miRNAs) participate in tumor growth and metastasis. Mesenchymal stem cells (MSCs) derived exosomes (Exos) are considered as better miRNA delivery vehicles. Here, we investigated the therapeutic effect of exosomal miR-499a-5p (miR-499) in human endometrial cancer metastasis.

Methods

Microarray analysis and RT-PCR were performed to detect the relative expression of miR-499 in endometrial cancer tissues and cell lines. MSC-derived Exos were characterized by transmission electron microscope (TEM), Western blot (WB), and nanoparticle tracking analysis (NTA). miR-499 was loading into Exos using electroporation. Cell proliferation and angiogenesis capacity were tested by 5-ethynyl-29-deoxyuridine (EdU) assay and tube formation assay, respectively. Dual-luciferase reporter assay (DLR) was used to confirm the connection of miR-499 and VAV3.

Results

We found that the expression of miR-499 was significantly downregulated in cancer tissues compared with adjacent tissues in endometrial cancer patients. Moreover, exosomal miR-499 not only dramatically suppressed endometrial cancer cells proliferation, endothelial cells tube formation in vitro, but also inhibited tumor growth and angiogenesis in vivo. In addition, we confirmed that miR-499 directly targets the 3'UTR sequence of VAV3.

Conclusion

The novel identified exosomal miR-499 functions as a tumor suppressor in endometrial cancer though regulating VAV3, and these findings could be a valid molecular target for endometrial cancer therapy.

The opposing roles of the mTOR signaling pathway in different phases of human umbilical cord blood-derived CD34+ cell erythropoiesis

As an indispensable, even lifesaving practice, red blood cell (RBC) transfusion is challenging due to several issues, including supply shortage, immune incompatibility, and blood-borne infections since donated blood is the only source of RBCs. Although large-scale in vitro production of functional RBCs from human stem cells is a promising alternative, so far, no such system has been reported to produce clinically transfusable RBCs due to the poor understanding of mechanisms of human erythropoiesis, which is essential for the optimization of in vitro erythrocyte generation system. We previously reported that inhibition of mammalian target of rapamycin (mTOR) signaling significantly decreased the percentage of erythroid progenitor cells in the bone marrow of wild-type mice. In contrast, rapamycin treatment remarkably improved terminal maturation of erythroblasts and anemia in a mouse model of β-thalassemia. In the present study, we investigated the effect of mTOR inhibition with rapamycin from different time points on human umbilical cord blood-derived CD34⁺ cell erythropoiesis in vitro and the underlying mechanisms. Our data showed that rapamycin treatment significantly suppressed erythroid colony formation in the commitment/proliferation phase of erythropoiesis through inhibition of cell-cycle progression and proliferation. In contrast, during the maturation phase of erythropoiesis, mTOR inhibition dramatically promoted enucleation and mitochondrial clearance by enhancing autophagy. Collectively, our results suggest contrasting roles for mTOR in regulating different phases of human erythropoiesis.

Two cosine wave elastic-plastic contact model

Based on Hertz elastic contact theory, the contact mechanics model of two cosine wave is established. The mechanical characteristics of the model in the elastic, elastic-plastic, and plastic stages were studied. The influence of load on contact deformation and other characteristics is considered. The finite element method is used to analyze the deformation process of the model, and the results are compared with those of the mechanical model. The effects of amplitude and wavelength of cosine wave on its mechanical characteristics are discussed. The results show that the model reflects the relationship between the load and the mechanical characteristics of the model, and the difference of amplitude and wavelength will affect this characteristic.

Photorefractive effect in LiNbO3-based integrated-optical circuits for continuous variable experiments

We investigate the impact of the photorefractive effect on lithium niobate integrated quantum photonic circuits dedicated to continuous variable on-chip experiments. The circuit main building blocks, i.e. cavities, directional couplers, and periodically poled nonlinear waveguides, are studied. This work demonstrates that photorefractivity, even when its effect is weaker than spatial mode hopping, might compromise the success of on-chip quantum photonics experiments. We describe in detail the characterization methods leading to the identification of this possible issue. We also study to which extent device heating represents a viable solution to counter this effect. We focus on photorefractive effect induced by light at 775 nm, in the context of the generation of non-classical light at 1550 nm telecom wavelength.

Self-rated health scores predict mortality among people with type 2 diabetes differently across three different country groupings: findings from the ADVANCE and ADVANCE-ON trials

AIMS

To explore whether there is a different strength of association between self-rated health and all-cause mortality in people with type 2 diabetes across three country groupings: nine countries grouped together as 'established market economies'; Asia; and Eastern Europe.

METHODS

The ADVANCE trial and its post-trial follow-up were used in this study, which included 11 140 people with type 2 diabetes from 20 countries, with a median follow-up of 9.9 years. Self-rated health was reported on a 0-100 visual analogue scale. Cox proportional hazard models were fitted to estimate the relationship between the visual analogue scale score and all-cause mortality, controlling for a range of demographic and clinical risk factors. Interaction terms were used to assess whether the association between the visual analogue scale score and mortality varied across country groupings.

RESULTS

The visual analogue scale score had different strengths of association with mortality in the three country groupings. A 10-point increase in visual analogue scale score was associated with a 15% (95% CI 12-18) lower mortality hazard in the established market economies, a 25% (95% CI 21-28) lower hazard in Asia, and an 8% (95% CI 3-13) lower hazard in Eastern Europe.

CONCLUSIONS

Self-rated health appears to predict 10-year all-cause mortality for people with type 2 diabetes worldwide, but this relationship varies across groups of countries.

DNA polymerase α interacts with H3-H4 and facilitates the transfer of parental histones to lagging strands

How parental histones, the carriers of epigenetic modifications, are deposited onto replicating DNA remains poorly understood. Here, we describe the eSPAN method (enrichment and sequencing of protein-associated nascent DNA) in mouse embryonic stem (ES) cells and use it to detect histone deposition onto replicating DNA strands with a relatively small number of cells. We show that DNA polymerase α (Pol α), which synthesizes short primers for DNA synthesis, binds histone H3-H4 preferentially. A Pol α mutant defective in histone binding in vitro impairs the transfer of parental H3-H4 to lagging strands in both yeast and mouse ES cells. Last, dysregulation of both coding genes and noncoding endogenous retroviruses is detected in mutant ES cells defective in parental histone transfer. Together, we report an efficient eSPAN method for analysis of DNA replication-linked processes in mouse ES cells and reveal the mechanism of Pol α in parental histone transfer.

Down-regulation of miR-1181 indicates a dismal prognosis for nasopharyngeal carcinoma and promoted cell proliferation and metastasis by modulating Wnt/β-catenin signaling

OBJECTIVE

Our study aimed to investigate the expression pattern, clinicopathological feature and prognostic role of miR-1181 in nasopharyngeal carcinoma (NPC), and to determine the functional effects and potential mechanism of miR-1181 in NPC.

PATIENTS AND METHODS

The expression levels of miR-1181 were determined in NPC tissues and cell lines by RT-PCR. The clinical data were interpreted by chi-square test, univariate analysis, and multivariate analysis. The effect of PVT1 on proliferation was evaluated by CCK-8 and colony formation assays, and migration and invasion ability were evaluated by transwell and wound-healing assays. The association between miR-1181 and Wnt/β-catenin pathway was analyzed by Western blot.

RESULTS

We found that miR-1181 expression was significantly down-regulated in both NPC tissues and cell lines. Low expression of miR-1181 was significantly associated with N stage (p=0.013), clinical stage (p=0.037) and grade (p=0.033). Clinical assays showed that patients with low miR-1181 expression had shorter overall survival time than those with high miR-1181 expression (p=0.0007). Multivariate analysis revealed that miR-1181 expression was independently associated with the overall survival. Functional investigations indicated that overexpression of miR-1181 suppressed NPC cells proliferation, migration and invasion. Mechanistically, forced miR-1181 expression suppressed the activity of Wnt/β-catenin pathway.

CONCLUSIONS

Our findings proved that miR-1181 may serve as a candidate prognostic biomarker and target for new therapies in NPC patients.

primirTSS: an R package for identifying cell-specific microRNA transcription start sites

SUMMARY

The R/Bioconductor package primirTSS is a fast and convenient tool that allows implementation of the analytical method to identify transcription start sites of microRNAs by integrating ChIP-seq data of H3K4me3 and Pol II. It further ensures the precision by employing the conservation score and sequence features. The tool showed a good performance when using H3K4me3 or Pol II Chip-seq data alone as input, which brings convenience to applications where multiple datasets are hard to acquire. This flexible package is provided with both R-programming interfaces as well as graphical web interfaces.

AVAILABILITY AND IMPLEMENTATION

primirTSS is available at: http://bioconductor.org/packages/primirTSS. The documentation of the package including an accompanying tutorial was deposited at: https://bioconductor.org/packages/release/bioc/vignettes/primirTSS/inst/doc/primirTSS.html.

CONTACT

jwang@nju.edu.cn.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Chromatin Assembly Factor 1 (CAF-1) facilitates the establishment of facultative heterochromatin during pluripotency exit

Establishment and subsequent maintenance of distinct chromatin domains during embryonic stem cell (ESC) differentiation are crucial for lineage specification and cell fate determination. Here we show that the histone chaperone Chromatin Assembly Factor 1 (CAF-1), which is recruited to DNA replication forks through its interaction with proliferating cell nuclear antigen (PCNA) for nucleosome assembly, participates in the establishment of H3K27me3-mediated silencing during differentiation. Deletion of CAF-1 p150 subunit impairs the silencing of many genes including Oct4, Sox2 and Nanog as well as the establishment of H3K27me3 at these gene promoters during ESC differentiation. Mutations of PCNA residues involved in recruiting CAF-1 to the chromatin also result in defects in differentiation in vitro and impair early embryonic development as p150 deletion. Together, these results reveal that the CAF-1-PCNA nucleosome assembly pathway plays an important role in the establishment of H3K27me3-mediated silencing during cell fate determination.

Research on the elastic-plastic external contact mechanical properties of cylinder

Based on Hertz contact theory, an elastic-plastic contact mechanics model of outer cylinder under different contact angles of axis is proposed. The relationship among contact angle, load and contact deformation, contact stiffness and contact area is established. The finite element method is used to simulate the elastic-plastic contact process of the cylinder. The influence of the load and radius of the cylinder model on the contact deformation and the contact stiffness is compared and analyzed under different contact angles. The error of the analysis results of the finite element and the mechanical model is within 9%. On this basis, the influence of contact deformation, contact area and contact angle on the contact stiffness of the outer cylinder in elastic and plastic stage is explored. The results show that in the stage of elastic and plastic deformation, the amount of contact deformation and contact area increase with the increase of load. The contact stiffness decreases with the increase of contact angle and increases with the increase of cylinder radius. The amount of contact deformation decreases with the increase of cylinder radius, and tends to constant gradually. In the elastic stage, the contact stiffness increases with the increase of load. The contact area decreases with the increase of contact angle and increases with the increase of cylinder radius. In the plastic stage, the contact stiffness is constant with the increase of load, and the contact area is independent of contact angle and cylinder radius.

Heterozygous deletion of Seipin in islet beta cells of male mice has an impact on insulin synthesis and secretion through reduced PPARγ expression

AIMS/HYPOTHESIS

Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) is an autosomal recessive disorder characterised by lipodystrophy and insulin resistance. BSCL2 is caused by loss-of-function mutations in the Seipin gene (also known as Bscl2). Deletion of this gene in mice induces insulin resistance, glucose intolerance and a loss of adipose tissue. This study evaluated the effects of genetic deletion of Seipin on islet beta cell function.

METHODS

We examined seipin expression in islet cells and measured glucose profiles, insulin synthesis, glucose-stimulated insulin secretion (GSIS), islet expression of peroxisome proliferator-activated receptor γ (PPARγ), levels of Pdx-1, Nkx6.1, Glut2 (also known as Slc2a2) and proinsulin mRNA, nuclear translocation of pancreatic duodenal homeobox 1 (PDX-1), islet numbers, and beta cell mass and proliferation in male and female Seipin-knockout homozygous (Seipin^-/-) and heterozygous (Seipin^+/-) mice.

RESULTS

Male and female Seipin^-/- mice displayed glucose intolerance, insulin resistance, hyperinsulinaemia and a lack of adipose tissue. By contrast, male but not female Seipin^+/- mice showed glucose intolerance without adipose tissue loss or insulin resistance. Seipin was highly expressed in islet beta cells in wild-type mice. Expression of islet PPARγ was reduced in male Seipin^-/- and Seipin^+/- mice but not in female Seipin^-/- or Seipin^+/- mice. Treatment of male Seipin^+/- mice with rosiglitazone corrected the glucose intolerance. Male Seipin^+/- mice displayed a decrease in islet insulin concentration and GSIS with low expression of Pdx-1, Nkx6.1, Glut2 and proinsulin, and a decline in PDX-1 nuclear translocation; these changes were rescued by rosiglitazone administration. Male Seipin^-/- mice showed obvious, but rosiglitazone-sensitive, increases in islet insulin concentration, islet number and beta cell mass and proliferation, with a notable decline in GSIS. Ovariectomised female Seipin^+/- mice displayed glucose intolerance and deficits in insulin synthesis and secretion, with a decline in islet PPARγ level; these deleterious effects were reversed by administration of oestradiol or rosiglitazone.

CONCLUSIONS/INTERPRETATION

Heterozygous deletion of Seipin in islet beta cells impacts on insulin synthesis and secretion through reduced PPARγ expression. This leads to glucose intolerance and is relieved by oestradiol, which rescues PPARγ expression.