Dual roles of histone H3 lysine-4 in antagonizing Polycomb group function and promoting target gene expression.

Tight control over cell identity gene expression is necessary for proper adult form and function. The opposing activities of Polycomb and trithorax complexes determine the ON/OFF state of targets like the Hox genes. Trithorax encodes a methyltransferase specific to histone H3 lysine-4 (H3K4). However, there is no direct evidence that H3K4 regulates Polycomb group target genes in vivo . Here, we demonstrate two key roles for replication-dependent histone H3.2K4 in target control. We find that H3.2K4 antagonizes Polycomb group catalytic activity and that it is required for proper target gene activation. We conclude that H3.2K4 directly regulates expression of Polycomb targets.

LONG-TERM NATURAL HISTORY OF PRESUMPTIVE DIVERTICULAR HEMORRHAGE.

OBJECTIVES: The natural history of patients with well-documented presumptive diverticular hemorrhage (TICH) is unknown. Our aims are to report: 1) rebleeding rates and clinical outcomes of presumptive TICH patients with and without rebleeding, 2) conversion to definitive TICH during long-term follow-up (F/U), and 3) risk factors for presumptive TIC rebleeding. METHODS: This was a retrospective cohort study of prospectively collected results of presumptive TICH patients from 1994 to 2023. Presumptive TICH was diagnosed for patients with TIC's without stigmata of recent hemorrhage and no other cause of bleeding found on anoscopy, enteroscopy, capsule endoscopy, computerized tomography angiography, or tagged red blood cell scan. Patients with ≤ 6 months of F/U were excluded. RESULTS: Of 139 patients with presumptive TICH, 104 were males and 35 females. Median age was 76 years. There were no significant differences in baseline demographics of rebleeders and non-rebleeders. During long-term median F/U of 73 months, 24.5% (34/139) rebled. 56% (19/34) of rebleeders were diagnosed as definitive TICH and they had significantly higher rates of readmission (p<0.001), reintervention (p<0.001), and surgery (p<0.001). During F/U, there were significantly higher rates of newly diagnosed hypertension (HTN) and/or atherosclerotic cardiovascular disease (ASCVD) in rebleeders (p = 0.033 from logistic model). All-cause mortality was 42.8%, but none was from TICH. CONCLUSIONS: For presumptive TICH during long-term F/U: 1) 75.5% did not rebleed and 24.5% rebled. 2) 56% of rebleeders were diagnosed as definitive TICH. 3) New development of HTN and ASCVD were risk factors for TIC rebleeding.

Redesigning the Drosophila histone gene cluster: An improved genetic platform for spatiotemporal manipulation of histone function.

Mutating replication-dependent (RD) histone genes is an important tool for understanding chromatin-based epigenetic regulation. Deploying this tool in metazoan models is particularly challenging because RD histones in these organisms are typically encoded by many genes, often located at multiple loci. Such RD histone gene arrangements make the ability to generate homogenous histone mutant genotypes by site-specific gene editing quite difficult. Drosophila melanogaster provides a solution to this problem because the RD histone genes are organized into a single large tandem array that can be deleted and replaced with transgenes containing mutant histone genes. In the last ∼15 years several different RD histone gene replacement platforms have been developed using this simple strategy. However, each platform contains weaknesses that preclude full use of the powerful developmental genetic capabilities available to Drosophila researchers. Here we describe the development of a newly engineered platform that rectifies many of these weaknesses. We used CRISPR to precisely delete the RD histone gene array ( HisC ), replacing it with a multifunctional cassette that permits site-specific insertion of either one or two synthetic gene arrays using selectable markers. We designed this cassette with the ability to selectively delete each of the integrated gene arrays in specific tissues using site-specific recombinases. We also present a method for rapidly synthesizing histone gene arrays of any genotype using Golden Gate cloning technologies. These improvements facilitate generation of histone mutant cells in various tissues at different stages of Drosophila development and provide an opportunity to apply forward genetic strategies to interrogate chromatin structure and gene regulation.

Examining trauma, anxiety, and depression as predictors of dropout from residential treatment for substance use disorders.

Substance use disorders (SUDs) are highly prevalent and have deleterious effects on one's health and well-being. Inpatient treatment for SUDs reduces patient relapse, which subsequently ameliorates these negative effects on the individual and society. Additionally, those who complete treatment are less likely to relapse compared to those who do not complete treatment. Thus, maintaining patient engagement in treatment and reducing the rates of those leaving against medical advice (AMA) is particularly important. Examining the factors and comorbidities that may contribute to treatment dropout has the potential to identify at-risk patients in need of additional individualized intervention. The current study aimed to examine comorbid anxiety, depression, and posttraumatic stress disorder (PTSD) symptoms as predictors of dropout AMA in a residential substance use treatment population. Results showed that patients with social anxiety were more likely to leave treatment AMA, while those with PTSD were more likely to complete treatment. Findings suggest that PTSD-specific treatment, as offered in this facility, may help with patient retention, while group focused therapy may be distressing to those with social anxiety. Clinical implications of this research may include incorporating evidence-based practice for social anxiety early during inpatient treatment to reduce anxiety such that patients may better engage with SUDs treatment.

Patient Outcomes of Definitive Diverticular Hemorrhage After Colonoscopic, Medical, Surgical, or Embolization Treatment.

BACKGROUND: There are few reports of clinical outcomes or the natural history of definitive diverticular hemorrhage (DDH). AIMS: To describe 1-year clinical outcomes of patients with documented DDH treated with colonoscopic hemostasis, angioembolization, surgery, or medical treatment. METHODS: DDH was diagnosed when active bleeding or other stigmata of hemorrhage were found in a colonic diverticulum during urgent colonoscopy or extravasation on angiography or red blood cell (RBC) scanning. This was a retrospective analysis of prospectively collected data of DDH patients from two referral centers between 1993 and 2022. Outcomes were compared for the four treatment groups. The Kaplan-Meier analysis was for time-to-first diverticular rebleed. RESULTS: 162 patients with DDH were stratified based on their final treatment before discharge-104 colonoscopic hemostasis, 24 medical treatment alone, 19 colon surgery, and 15 angioembolization. There were no differences in baseline characteristics, except for a higher Glasgow-Blatchford score in the angioembolization group vs. the colonoscopic group. Post-treatment, the colonoscopic hemostasis group had the lowest rate of RBC transfusions and fewer hospital and ICU days compared to surgical and embolization groups. The medical group had significantly higher rates of rebleeding and reintervention. The surgical group had the highest postoperative complications. CONCLUSIONS: Medically treated DDH patients had significantly higher 1-year rebleed and reintervention rates than the three other treatments. Those with colonoscopic hemostasis had significantly better clinical outcomes during the index hospitalization. Surgery and embolization are recommended as salvage therapies in case of failure of colonoscopic and medical treatments.

The SWI/SNF nucleosome remodeler constrains enhancer activity during Drosophila wing development.

Chromatin remodeling is central to the dynamic changes in gene expression that drive cell fate determination. During development, the sets of enhancers that are accessible for use change globally as cells transition between stages. While transcription factors and nucleosome remodelers are known to work together to control enhancer accessibility, it is unclear how the short stretches of DNA that they individually unmask yield the kilobase-sized accessible regions characteristic of active enhancers. Here, we performed a genetic screen to investigate the role of nucleosome remodelers in control of dynamic enhancer activity. We find that the Drosophila Switch/Sucrose Non-Fermenting complex, BAP, is required for repression of a temporally dynamic enhancer, brdisc. Contrary to expectations, we find that the BAP-specific subunit Osa is dispensable for mediating changes in chromatin accessibility between the early and late stages of wing development. Instead, we find that Osa is required to constrain the levels of brdisc activity when the enhancer is normally active. Genome-wide profiling reveals that Osa directly binds brdisc as well as thousands of other developmentally dynamic regulatory sites, including multiple genes encoding components and targets of the Notch signaling pathway. Transgenic reporter analyses demonstrate that Osa is required for activation and for constraint of different sets of target enhancers in the same cells. Moreover, Osa loss results in hyperactivation of the Notch ligand Delta and development of ectopic sensory structures patterned by Notch signaling early in development. Together, these findings indicate that proper constraint of enhancer activity is necessary for regulation of dose-dependent developmental events.

Case Report: Methotrexate and hydroxychloroquine in combination for the treatment of NOD2-mutation-associated Blau syndrome.

Mutations in nucleotide binding oligomerization domain containing 2 receptor (NOD2) are associated with Blau syndrome (also known as early-onset sarcoidosis)-a rare autosomal dominant, chronic granulomatous disease that typically presents before 5 years of age. Blau syndrome is characterized by the clinical triad of arthritis, granulomatous dermatitis, and recurrent uveitis. Here, we report a case of NOD2-mutation-associated early-onset sarcoidosis in which a combination of methotrexate and hydroxychloroquine was used to achieve improvement in arthritis, granulomatous dermatitis, and uveitis. A 13-month-old boy presented with a sudden-onset cutaneous eruption affecting the face, trunk, and extremities that initially mimicked papular atopic dermatitis but progressively worsened despite topical steroid therapy. The patient had no other known medical comorbidities or abnormalities except for heterochromia of the right eye. However, prior to presentation to dermatology, the patient began experiencing frequent falls, conjunctival injection, and apparent eye and joint pain. Skin biopsy from the right shoulder demonstrated rounded aggregates of epithelioid histiocytes and multinucleated giant cells without a significant lymphocytic component ("naked granulomas"), consistent with sarcoidal granulomatous dermatitis. Given the concern for Blau syndrome, the patient was sent for evaluation by ophthalmology and was found to have bilateral subconjunctival nodules. Our patient underwent genetic testing and was found to have a mutation in codon 1000 C > T (protein R334W) in the NOD2 gene. The patient responded to oral prednisolone 2 mg/kg/day for 8 weeks, but quickly relapsed, requiring a second 8-week course with taper upon starting methotrexate 7.5 mg subcutaneously weekly with 1 mg folic acid orally daily. After 8 weeks on methotrexate, due to persistent arthritis, conjunctival injection, and pruritus, and in consultation with rheumatology, the patient was started on hydroxychloroquine 75 mg orally daily along with continuation of 7.5 mg methotrexate subcutaneously weekly for 8 weeks, achieving significant reduction in arthritis, pruritus, and uveitis. After 8 weeks of this combination therapy, due to concerns of long-term macular toxicity, hydroxychloroquine was discontinued in favor of continuing methotrexate alone. The patient has remained free of significant side effects and stable with good disease control on 7.5 mg methotrexate weekly injected subcutaneously.

Alcohol Use and Compulsive Sexual Behaviors in College Students: The Moderating Effect of Alcohol-Related Sexual Expectancies.

Compulsive sexual behaviors (CSB) and alcohol use are prevalent among college students. Alcohol use frequently co-occurs with CSB; however, further examination of risk factors of co-occurring alcohol use and CSB is needed. We examined the moderating effect of alcohol-related sexual expectancies, specifically sexual drive and affect expectancies, on the association between alcohol use/problems and CSB among 308 college students from a large university in the southeastern United States. Alcohol use/problems and CSB had a positive significant relationship among college students high in sexual drive expectancies and high and average in sexual affect expectancies. These findings suggest that alcohol-related sexual expectancies may be a risk factor for alcohol-related CSB.

Distinct roles for canonical and variant histone H3 lysine-36 in Polycomb silencing.

Polycomb complexes regulate cell type-specific gene expression programs through heritable silencing of target genes. Trimethylation of histone H3 lysine 27 (H3K27me3) is essential for this process. Perturbation of H3K36 is thought to interfere with H3K27me3. We show that mutants of Drosophila replication-dependent (H3.2K36R) or replication-independent (H3.3K36R) histone H3 genes generally maintain Polycomb silencing and reach later stages of development. In contrast, combined (H3.3K36RH3.2K36R) mutants display widespread Hox gene misexpression and fail to develop past the first larval stage. Chromatin profiling revealed that the H3.2K36R mutation disrupts H3K27me3 levels broadly throughout silenced domains, whereas these regions are mostly unaffected in H3.3K36R animals. Analysis of H3.3 distributions showed that this histone is enriched at presumptive Polycomb response elements located outside of silenced domains but relatively depleted from those inside. We conclude that H3.2 and H3.3 K36 residues collaborate to repress Hox genes using different mechanisms.

Opportunistic binding of EcR to open chromatin drives tissue-specific developmental responses.

Steroid hormones perform diverse biological functions in developing and adult animals. However, the mechanistic basis for their tissue specificity remains unclear. In Drosophila, the ecdysone steroid hormone is essential for coordinating developmental timing across physically separated tissues. Ecdysone directly impacts genome function through its nuclear receptor, a heterodimer of the EcR and ultraspiracle proteins. Ligand binding to EcR triggers a transcriptional cascade, including activation of a set of primary response transcription factors. The hierarchical organization of this pathway has left the direct role of EcR in mediating ecdysone responses obscured. Here, we investigate the role of EcR in controlling tissue-specific ecdysone responses, focusing on two tissues that diverge in their response to rising ecdysone titers: the larval salivary gland, which undergoes programmed destruction, and the wing imaginal disc, which initiates morphogenesis. We find that EcR functions bimodally, with both gene repressive and activating functions, even at the same developmental stage. EcR DNA binding profiles are highly tissue-specific, and transgenic reporter analyses demonstrate that EcR plays a direct role in controlling enhancer activity. Finally, despite a strong correlation between tissue-specific EcR binding and tissue-specific open chromatin, we find that EcR does not control chromatin accessibility at genomic targets. We conclude that EcR contributes extensively to tissue-specific ecdysone responses. However, control over access to its binding sites is subordinated to other transcription factors.

miR-130b/301b Is a Negative Regulator of Beige Adipogenesis and Energy Metabolism In Vitro and In Vivo.

Thermogenic brown or beige adipocytes dissipate energy in the form of heat and thereby counteract obesity and related metabolic complications. The miRNA cluster miR-130b/301b is highly expressed in adipose tissues and has been implicated in metabolic diseases as a posttranscriptional regulator of mitochondrial biogenesis and lipid metabolism. We investigated the roles of miR-130b/301b in regulating beige adipogenesis in vivo and in vitro. miR-130b/301b declined in adipose progenitor cells during beige adipogenesis, while forced overexpression of miR-130b-3p or miR-301b-3p suppressed uncoupling protein 1 (UCP1) and mitochondrial respiration, suggesting that a decline in miR-130b-3p or miR-301b-3p is required for adipocyte precursors to develop the beige phenotype. Mechanistically, miR-130b/301b directly targeted AMP-activated protein kinase (AMPKα1) and suppressed peroxisome proliferator-activated receptor γ coactivator-1α (Pgc-1α), key regulators of brown adipogenesis and mitochondrial biogenesis. Mice lacking the miR-130b/301b miRNA cluster showed reduced visceral adiposity and less weight gain. miR-130b/301b null mice exhibited improved glucose tolerance, increased UCP1 and AMPK activation in subcutaneous fat (inguinal white adipose tissue [iWAT]), and increased response to cold-induced energy expenditure. Together, these data identify the miR-130b/301b cluster as a new regulator that suppresses beige adipogenesis involving PGC-1α and AMPK signaling in iWAT and is therefore a potential therapeutic target against obesity and related metabolic disorders.

A basal actinopterygian melanocortin receptor: Molecular and functional characterization of an Mc2r ortholog from the Senegal bichir (Polypterus senegalus).

In bony vertebrates, melanocortin 2 receptor (Mc2r) specifically binds adrenocorticotropic hormone (ACTH) and is responsible for mediating anterior pituitary signaling that stimulates corticosteroid production in the adrenal gland/interrenal cells. In bony fishes Mc2r requires the chaperoning of an accessory protein (Mrap1) to traffic to the membrane surface and bind ACTH. Here, we evaluated the structure and pharmacological properties of Mc2r from the Senegal bichir (Polypterus senegalus), which represents the most basal bony fish from which an Mc2r has been pharmacologically studied to date. In our experiments, cDNA constructs of the Mc2r from the Senegal bichir (sbMc2r) and various vertebrate Mrap1s were heterologously co-expressed in Chinese hamster ovary (CHO) cells, stimulated by ACTH or melanocyte-stimulating hormone (α-MSH) ligands, and assessed using a luciferase reporter gene assay. When expressed without an Mrap1, sbMc2r was not activated by ACTH. When co-expressed with Mrap1 from either chicken (Gallus gallus) or bowfin (Amia calva), sbMc2r could be activated in a dose-dependent manner by ACTH, but not α-MSH. Co-expression of sbMrap2 with sbMc2r resulted in no detectable activation of the receptor. Collectively, these results demonstrate that sbMc2r has pharmacological properties similar to those of Mc2rs of later-evolved bony fishes, such as Mrap1 dependence and ACTH selectivity, indicating that these qualities of Mc2r function are ancestral to all bony fish Mc2rs.

Impact of maternal diabetes exposure on soluble adhesion molecules in the offspring.

BACKGROUND AND AIMS: Soluble adhesion molecules are associated with cardiovascular disease and increased in individuals with diabetes. This study assesses the impact of diabetes exposure in utero on the abundance of circulating adhesion molecules in cord serum and soluble adhesion molecules released from human umbilical vein endothelial cells (HUVEC) exposed to high glucose concentrations. METHODS AND RESULTS: Women with and without diabetes were recruited. DM was diagnosed based on the American Diabetes Association criteria. Primary cultures of HUVEC were cultured in 5 mM and 25 mM glucose with 25 mM mannitol osmotic control. The soluble adhesion molecules, intracellular adhesion molecule (ICAM), vascular cell adhesion molecule (VCAM) and E-selectin were measured by ELISA in the cord blood serum and conditioned HUVEC media. The mothers with DM were older with higher BMI (p = 0.027 and 0.008, respectively). In a fully adjusted model, VCAM was significantly increased in the cord serum of infants born to mothers with diabetes (p = 0.046), but ICAM and E-selectin were not different. ICAM was also significantly correlated with maternal HbA1c (r2 = 0.16, p = 0.004) and cord serum non-esterified fatty acids (r2 = 0.08, p = 0.013). From the HUVEC media, the abundance of adhesion molecules was not different based on DM or high glucose exposure; however, VCAM abundance in the HUVEC supernatant was significantly correlated with ICAM (r2 = 0.27, p = 0.010) and cord serum c-peptide (R2 = 0.19, p = 0.043). CONCLUSIONS: Alterations in soluble adhesion molecule abundance in infants exposed to the diabetic milieu of pregnancy may reflect early alterations in vascular function predicting future cardiovascular disease.

Outcomes of patients with ischemic colitis causing severe hematochezia managed medically or surgically.

PURPOSE: To compare short- and long-term outcomes of hospitalized patients with ischemic colitis (IC) presenting with severe hematochezia and treated medically or colectomy and also those with inpatient vs. outpatient start of hematochezia. METHODS: A retrospective analysis of prospectively collected data for IC patients hospitalized for severe hematochezia from two teaching hospitals was done from 1994 to 2020, with the diagnosis of IC made colonoscopically and confirmed histologically. RESULTS: Ninety-seven patients initially all had medical management for IC. Seventy-two (74.2%) were stable and had no further bleeding; 17 (17.5%) had colon resection; and 8 were critically ill and not surgical candidates. Surgical patients and non-surgical candidate had higher comorbidity scores; received more red blood cell (RBC) transfusion (median (IQR) 5 (3-10) vs. 4.5 (3-6.5) vs. 1 (0-4) units, p < 0.001); had significantly longer hospital and ICU days; had higher severe complication rates (35.3% vs. 100%. vs. 5.6%, p < 0.001); and had higher 30-day all-cause mortality rates (23.5% vs. 87.5% vs. 0, p < 0.001). Inpatients developing IC hemorrhage had more RBC transfusions, more complications, longer hospital stays, and higher mortality than patients whose IC bleeding started as outpatients. CONCLUSIONS: The majority of IC patients hospitalized for severe hematochezia were successfully treated medically. Patients who were not surgical candidate had the highest rates of severe complications and mortality. Surgical patients and those who were not surgical candidate had worse outcomes than the medical group. Patients with inpatient start of bleeding from IC had significantly worse outcomes than those with outpatient start of bleeding.

Metabolic and Genetic Risk Factors Are the Strongest Predictors of Severity of Alcohol-Related Liver Fibrosis.

BACKGROUND & AIMS: Individual risk for developing alcohol-related liver disease (ALD) varies greatly. We hypothesized that metabolic risk factors and genetic polymorphisms predict severity of ALD. METHODS: Biopsy-controlled, cross-sectional study in patients with a history of excessive drinking. We measured the homeostatic model assessment of insulin resistance (HOMA-IR), plasma triglycerides, high- and low-density lipoproteins (HDL, LDL), and total cholesterol. Moreover, we genotyped four single nucleotide polymorphisms in PNPLA3 (rs738409C>G), TM6SF2 (rs58542926C>T), MBOAT7 (rs641738C>T), and HSD17B13 (rs72613567T>TA). We assessed predictors of higher fibrosis stage using multivariable ordered logistic regression. RESULTS: Of 325 included patients, 25% had severe fibrosis or cirrhosis and 59% had HOMA-IR ≥2.5. HOMA-IR increased for each fibrosis stage, while there was a similar decrease in LDL and total cholesterol. Individuals with risk variant PNPLA3 rs738409-G or TM6SF2 rs58542926-T had higher fibrosis stage. In multivariable regression, HOMA-IR ≥2.5 (OR = 3.04, 95% CI 1.90-4.87), LDL <2.60 mmol/L (OR = 2.05, 95% CI 1.33-3.16), TM6SF2 rs58542926-T (OR = 1.99, 95% CI 1.17-3.37), age above 50 years (OR = 1.66, 95% CI 1.03-2.70), and PNPLA3 rs738409-G (OR = 1.54, 95% CI 1.11-2.12) independently predicted higher fibrosis stage. Independent predictors of hepatic inflammatory activity were HOMA-IR, active drinking, age, and PNPLA3 risk variant. Active drinking, elevated triglycerides, and PNPLA3 risk variant predicted steatosis. CONCLUSIONS: Insulin resistance is the strongest predictor of liver fibrosis stage and hepatic inflammation in patients with alcohol-related liver disease. Genetic susceptibility further aggravates this risk. These data highlight the clinical value of detailed metabolic and genetic profiling of patients with excessive alcohol use.

Severe Upper Gastrointestinal Hemorrhage Caused by Reflux Esophagitis.

BACKGROUND: There are few reports about reflux esophagitis (RE) as a cause of severe upper gastrointestinal bleeding (UGIB). AIMS: This study aims to evaluate (1) changes in its prevalence over the last three decades and (2) clinical and endoscopic characteristics and 30-day outcomes among RE patients with and without focal esophageal ulcers (EUs) and stigmata of recent hemorrhage (SRH). METHODS: A retrospective study of prospectively collected data of esophagitis patients hospitalized with severe UGIB between 1992 and 2020. Descriptive analysis and statistical comparisons were performed. RESULTS: Of 114 RE patients, the mean age was 61.1 years and 76.3% were males. 38.6% had prior gastroesophageal reflux disease (GERD) symptoms; overall 36% were on acid suppressants. Over three consecutive decades, the prevalence of RE as a cause of severe UGIB increased significantly from 3.8 to 16.7%. 30-day rebleeding and all-cause mortality rates were 11.4% and 6.1%. RE patients with focal EUs and SRH (n = 23) had worse esophagitis than those with diffuse RE (n = 91) (p = 0.012). There were no differences in 30-day outcomes between RE patients with and without EUs and SRH. CONCLUSIONS: For patients with severe UGIB caused by RE, (1) the prevalence has increased significantly over the past three decades, (2) the reasons for this increase and preventive strategies warrant further study, (3) most patients lacked GERD symptoms and did not take acid suppressants, and (4) those with focal ulcers and SRH had more severe esophagitis and were treated endoscopically.

A DELPHI consensus statement on antiplatelet management for intracranial stenting due to underlying atherosclerosis in the setting of mechanical thrombectomy.

PURPOSE: There is little data and lack of consensus regarding antiplatelet management for intracranial stenting due to underlying intracranial atherosclerosis in the setting of endovascular treatment (EVT). In this DELPHI study, we aimed to assess whether consensus on antiplatelet management in this situation among experienced experts can be achieved, and what this consensus would be. METHODS: We used a modified DELPHI approach to address unanswered questions in antiplatelet management for intracranial stenting due to underlying atherosclerosis in the setting of EVT. An expert-panel (19 neurointerventionalists from 8 countries) answered structured, anonymized on-line questionnaires with iterative feedback-loops. Panel-consensus was defined as agreement ≥ 70% for binary closed-ended questions/≥ 50% for closed-ended questions with > 2 response options. RESULTS: Panel members answered a total of 5 survey rounds. They acknowledged that there is insufficient data for evidence-based recommendations in many aspects of antiplatelet management for intracranial stenting due to underlying atherosclerosis in the setting of EVT. They believed that antiplatelet management should follow a standardized regimen, irrespective of imaging findings and reperfusion quality. There was no consensus on the timing of antiplatelet-therapy initiation. Aspirin was the preferred antiplatelet agent for the peri-procedural period, and oral Aspirin in combination with a P2Y12 inhibitor was the favored postprocedural regimen. CONCLUSION: Data on antiplatelet management for intracranial stenting due to underlying atherosclerosis in the setting of EVT are limited. Panel-members in this study achieved consensus on postprocedural antiplatelet management but did not agree upon a preprocedural and intraprocedural antiplatelet regimen. Further prospective studies to optimize antiplatelet regimens are needed.

Role of metformin in epigenetic regulation of placental mitochondrial biogenesis in maternal diabetes.

Adverse maternal environments, such as diabetes and obesity, impair placental mitochondrial function, which affects fetal development and offspring long-term health. The underlying mechanisms and effective interventions to abrogate such effect remain unclear. Our previous studies demonstrated impaired mitochondrial biogenesis in male human placenta of diabetic mothers. In the present studies, epigenetic marks possibly related to mitochondrial biogenesis in placentae of women with diabetes (n = 23) and controls (n = 23) were analyzed. Effects of metformin were examined in human placental explants from a subgroup of diabetic women and in a mouse model of maternal high fat diet feeding. We found that maternal diabetes was associated with epigenetic regulation of mitochondrial biogenesis in human placenta in a fetal sex-dependent manner, including decreased histone acetylation (H3K27 acetylation) and increased promoter methylation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). In male placenta, the levels of H3K27 acetylation and PGC-1α promoter methylation correlated significantly with the activity of AMP-activated protein kinase (AMPK). Metformin treatment on male diabetic placental explant activated AMPK and stimulated PGC-1α expression, concomitant with increased H3K27 acetylation and decreased PGC-1α promoter methylation. In vivo, we show that maternal metformin treatment along with maternal high fat diet significantly increased mouse placental abundance of PGC-1α expression and downstream mitochondrial transcription factor A (TFAM) and inhibited maternal high fat diet-impaired placental efficiency and glucose tolerance in offspring. Together, these findings suggest the capability of metformin to stimulate placental mitochondrial biogenesis and inhibit the aberrant epigenetic alterations occurring in maternal diabetes during pregnancy, conferring protective effects on offspring.

Lysine 27 of replication-independent histone H3.3 is required for Polycomb target gene silencing but not for gene activation.

Proper determination of cell fates depends on epigenetic information that is used to preserve memory of decisions made earlier in development. Post-translational modification of histone residues is thought to be a central means by which epigenetic information is propagated. In particular, modifications of histone H3 lysine 27 (H3K27) are strongly correlated with both gene activation and gene repression. H3K27 acetylation is found at sites of active transcription, whereas H3K27 methylation is found at loci silenced by Polycomb group proteins. The histones bearing these modifications are encoded by the replication-dependent H3 genes as well as the replication-independent H3.3 genes. Owing to differential rates of nucleosome turnover, H3K27 acetylation is enriched on replication-independent H3.3 histones at active gene loci, and H3K27 methylation is enriched on replication-dependent H3 histones across silenced gene loci. Previously, we found that modification of replication-dependent H3K27 is required for Polycomb target gene silencing, but it is not required for gene activation. However, the contribution of replication-independent H3.3K27 to these functions is unknown. Here, we used CRISPR/Cas9 to mutate the endogenous replication-independent H3.3K27 to a non-modifiable residue. Surprisingly, we find that H3.3K27 is also required for Polycomb target gene silencing despite the association of H3.3 with active transcription. However, the requirement for H3.3K27 comes at a later stage of development than that found for replication-dependent H3K27, suggesting a greater reliance on replication-independent H3.3K27 in post-mitotic cells. Notably, we find no evidence of global transcriptional defects in H3.3K27 mutants, despite the strong correlation between H3.3K27 acetylation and active transcription.