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Twitter-Delivered Behavioral Weight-Loss Interventions: A Pilot Series

Mon, 12/07/2015 - 3:03pm

BACKGROUND: Lifestyle interventions are efficacious at reducing risk for diabetes and cardiovascular disease but have not had a significant public health impact given high cost and patient and provider burden.

OBJECTIVE: Online social networks may reduce the burden of lifestyle interventions to the extent that they displace in-person visits and may enhance opportunities for social support for weight loss.

METHODS: We conducted an iterative series of pilot studies to evaluate the feasibility and acceptability of using online social networks to deliver a lifestyle intervention.

RESULTS: In Study 1 (n=10), obese participants with depression received lifestyle counseling via 12 weekly group visits and a private group formed using the online social network, Twitter. Mean weight loss was 2.3 pounds (SD 7.7; range -19.2 to 8.2) or 1.2% (SD 3.6) of baseline weight. A total of 67% (6/9) of participants completing exit interviews found the support of the Twitter group at least somewhat useful. In Study 2 (n=11), participants were not depressed and were required to be regular users of social media. Participants lost, on average, 5.6 pounds (SD 6.3; range -15 to 0) or 3.0% (SD 3.4) of baseline weight, and 100% (9/9) completing exit interviews found the support of the Twitter group at least somewhat useful. To explore the feasibility of eliminating in-person visits, in Study 3 (n=12), we delivered a 12-week lifestyle intervention almost entirely via Twitter by limiting the number of group visits to one, while using the same inclusion criteria as that used in Study 2. Participants lost, on average, 5.4 pounds (SD 6.4; range -14.2 to 3.9) or 3.0% (SD 3.1) of baseline weight, and 90% (9/10) completing exit interviews found the support of the Twitter group at least somewhat useful. Findings revealed that a private Twitter weight-loss group was both feasible and acceptable for many patients, particularly among regular users of social media.

CONCLUSIONS: Future research should evaluate the efficacy and cost-effectiveness of online social network-delivered lifestyle interventions relative to traditional modalities.

Improving Health Information Literacy of Early Adolescents Using a Lead Poisoning Curriculum

Mon, 12/07/2015 - 1:20pm

The purpose of this community outreach project was to improve health information literacy skills and lead poisoning knowledge in underserved early adolescents. An interactive curriculum focusing on one website (MedlinePlus) and one health issue (lead poisoning) was developed and used at an inner city school. Pre- and post-program surveys were used to assess the effectiveness of the curriculum. Results showed statistically significant improvements in both health information literacy skills and lead poisoning knowledge of 42 sixth graders. University-led community outreach collaborations to deliver an interactive curriculum in the school setting is a successful model for teaching health information literacy skills to early adolescents.

Human adipose tissue expansion in pregnancy is impaired in gestational diabetes mellitus

Sat, 12/05/2015 - 9:55pm

AIMS/HYPOTHESIS: During pregnancy, adipose tissue (AT) must expand to support the growing fetus and the future nutritional needs of the offspring. Limited expandability of AT is associated with insulin resistance, attributed to ectopic lipid deposition. This study aimed to investigate human AT expandability during pregnancy and its role in the pathogenesis of gestational diabetes mellitus (GDM).

METHODS: This cross-sectional study of omental (OM) and subcutaneous (SQ) AT collected at Caesarean delivery included 11 pregnant and three non-pregnant women with normal glucose tolerance (NGT), five with GDM, three with type 2 diabetes mellitus. Adipocyte size, capillary density, collagen content and capillary growth were measured. Affymetrix arrays and real-time PCR studies of gene expression were performed.

RESULTS: Mean OM adipocyte size was greater in women with GDM than in those with NGT (p = 0.004). Mean OM and SQ capillary density was lower in GDM compared with NGT (p = 0.015). Capillary growth did not differ significantly between groups. The most differentially expressed AT transcript when comparing non-pregnant and pregnant women corresponded to the IGF binding protein (IGFBP)-5, the expression levels of which was found by subsequent quantitative real-time PCR to be lower in women with GDM vs women with NGT (p < 0.0001).

CONCLUSIONS/INTERPRETATION: The relative OM adipocyte hypertrophy and decreased OM and SQ capillary density are consistent with impaired AT expandability in GDM. The induction of adipose tissue IGFBP5 in pregnancy and its decrease in GDM point to the importance of the IGF-1 signalling pathway in AT expansion in pregnancy and GDM susceptibility.

Cervical cancer screening and follow-up in 4 geographically diverse US health care systems, 1998 through 2007

Sat, 12/05/2015 - 9:55pm

BACKGROUND: Cervical cancer screening and follow-up guidelines have changed considerably in recent years, but to the authors' knowledge few published reports exist to estimate the impact of these changes in community-based settings. The authors examined the patterns and results of cervical cancer testing and follow-up over a decade in 4 geographically diverse US health care systems to inform the future evaluation of changes resulting from increased uptake of the human papillomavirus (HPV) vaccination.

METHODS: The authors studied women aged 21 to 65 years who were members of one of these health systems at any time between 1998 and 2007. Data were collected and standardized across sites, based on receipt of Papanicolaou (Pap) and HPV tests, HPV vaccination, cervical biopsies, and treatment of cervical dysplasia. Annual rates (per 1000 person-years) of Pap testing, HPV testing, and cervical biopsy and treatment procedures were calculated. Screening intervals and trends in the results of screening Pap tests and cervical biopsies also were examined.

RESULTS: Pap testing rates decreased (from 483 per 1000 person-years in 2000 to 412 per 1000 person-years in 2007) and HPV testing rates increased over the study period. Screening frequency varied across health care systems, and many women continued to receive annual testing. All 4 sites moved to less frequent screening over the study period without marked changes in the overall use of cervical biopsy or treatment.

CONCLUSIONS: Despite differences over time and across health plans in rates of cervical cancer testing and follow-up cervical procedures, the authors found no notable differences in Pap test results, diagnostic or treatment procedure rates, or pathological outcomes. This finding suggests that the longer screening intervals did not lead to more procedures or more cancer diagnoses.

An update on immunopathogenesis, diagnosis, and treatment of multiple sclerosis

Sat, 12/05/2015 - 9:55pm

BACKGROUND: Multiple sclerosis is an acquired demyelinating disease of the central nervous system. It is the second most common cause of disability in adults in United States after head trauma.

DISCUSSION: The etiology of MS is probably multifactorial, related to genetic, environmental, and several other factors. The pathogenesis is not fully understood but is believed to involve T-cell-mediated inflammation directed against myelin and other related proteins with a possible role for B cells. The McDonald criteria have been proposed and revised over the years to guide the diagnosis of MS and are based on clinical presentation and magnetic resonance imaging (MRI) of the brain and spinal cord to establish dissemination in time and space. The treatment of MS includes disease modification with immunomodulator drugs and symptom management to address the specific symptoms such as fatigue, spasticity, and pain.

CONCLUSION: An update on etiology, pathogenesis, diagnosis, and immunomodulatory treatment of MS is presented.

Perspectives in Implementing a Pragmatic Pediatric Primary Care-Based Intervention Trial

Sat, 12/05/2015 - 9:55pm

The 2013 U.S. Preventive Services Task Force (USPSTF) concluded that behavioral interventions are effective in reducing initiation of smoking in youth, recommending primary care clinicians provide education or brief counseling to prevent initiation, and that there are promising trends toward behavioral interventions improving cessation in this population. Our primary care-based intervention RCT conducted between 2000 and 2004, Air It Out, informed these USPSTF recommendations. Our trial was designed to determine whether a pediatric primary care practice-based smoking prevention and cessation intervention would be effective in increasing abstinence rates among adolescents under usual clinic conditions, to inform clinical practice. Therefore, the trial was designed to be largely a pragmatic trial. In this paper, we describe where each of the Air It Out study components falls along the pragmatic-explanatory continuum regarding participant eligibility criteria, intervention and comparison condition design, follow-up and outcomes, compliance and adherence assessments, and analysis. Such an assessment assists researchers by providing a framework to guide decisions regarding study design and implementation. We then share a few principles and lessons learned in developing and implementing the primary care-based intervention trial, focusing on study setting selection, engaging providers who will be delivering the intervention and the target population who will be receiving it in designing the trial and interventions to be tested, and the need to carefully plan recruitment and retention procedures. The hope is to increase the number of well-designed studies that can be included in the evidence reviews to guide future USPSTF recommendation statements.

Weekly Treatment of 2-Hydroxypropyl-beta-cyclodextrin Improves Intracellular Cholesterol Levels in LDL Receptor Knockout Mice

Sat, 12/05/2015 - 9:55pm

Recently, the importance of lysosomes in the context of the metabolic syndrome has received increased attention. Increased lysosomal cholesterol storage and cholesterol crystallization inside macrophages have been linked to several metabolic diseases, such as atherosclerosis and non-alcoholic fatty liver disease (NAFLD). Two-hydroxypropyl-beta-cyclodextrin (HP-B-CD) is able to redirect lysosomal cholesterol to the cytoplasm in Niemann-Pick type C1 disease, a lysosomal storage disorder. We hypothesize that HP-B-CD ameliorates liver cholesterol and intracellular cholesterol levels inside Kupffer cells (KCs). Hyperlipidemic low-density lipoprotein receptor knockout (Ldlr(-/-)) mice were given weekly, subcutaneous injections with HP-B-CD or control PBS. In contrast to control injections, hyperlipidemic mice treated with HP-B-CD demonstrated a shift in intracellular cholesterol distribution towards cytoplasmic cholesteryl ester (CE) storage and a decrease in cholesterol crystallization inside KCs. Compared to untreated hyperlipidemic mice, the foamy KC appearance and liver cholesterol remained similar upon HP-B-CD administration, while hepatic campesterol and 7alpha-hydroxycholesterol levels were back increased. Thus, HP-B-CD could be a useful tool to improve intracellular cholesterol levels in the context of the metabolic syndrome, possibly through modulation of phyto- and oxysterols, and should be tested in the future. Additionally, these data underline the existence of a shared etiology between lysosomal storage diseases and NAFLD.

Protein conformation in a vaccine matters

Sat, 12/05/2015 - 9:55pm

Virus-like particles (VLPs) are increasingly being considered as vaccine candidates for a variety of human and animal pathogens. Our results demonstrate that the conformation of antigens in VLPs is of critical importance for optimal stimulation of protective as well as durable immune responses.

Homozygous ALOXE3 Nonsense Variant Identified in a Patient with Non-Bullous Congenital Ichthyosiform Erythroderma Complicated by Superimposed Bullous Majocchi's Granuloma: The Consequences of Skin Barrier Dysfunction

Sat, 12/05/2015 - 9:55pm

Non-bullous congenital ichthyosiform erythroderma (NBCIE) is a hereditary disorder of keratinization caused by pathogenic variants in genes encoding enzymes important to lipid processing and terminal keratinocyte differentiation. Impaired function of these enzymes can cause pathologic epidermal scaling, significantly reduced skin barrier function. In this study, we have performed a focused, genetic analysis of a probrand affected by NBCIE and extended this to his consanguineous parents. Targeted capture and next-generation sequencing was performed on NBCIE associated genes in the proband and his unaffected consanguineous parents. We identified a homozygous nonsense variant c.814C > T (p.Arg272*) in ALOXE3 (NM_001165960.1) in the proband and discovered that his parents are both heterozygous carriers of the variant. The clinical manifestations of the proband's skin were consistent with NBCIE, and detailed histopathological assessment revealed epidermal bulla formation and Majocchi's granuloma. Infection with Trichophyton rubrum was confirmed by culture. The patient responded to oral terbinafine antifungal treatment. Decreased skin barrier function, such as that caused by hereditary disorders of keratinization, can increase the risk of severe cutaneous fungal infections and the formation of Majocchi's granuloma and associated alopecia. Patients with NBCIE should be alerted to the possible predisposition for developing dermatophytoses and warrant close clinical follow-up.

Evaluating implementation of methicillin-resistant Staphylococcus aureus (MRSA) prevention guidelines in spinal cord injury centers using the PARIHS framework: a mixed methods study

Sat, 12/05/2015 - 9:55pm

BACKGROUND: To prevent methicillin-resistant Staphylococcus aureus (MRSA) in Spinal Cord Injury and Disorder (SCI/D) Centers, the "Guidelines for Implementation of MRSA Prevention Initiative in the Spinal Cord Injury Centers" were released in July 2008 in the Veterans Affairs (VA) Health Care System. The purpose of this study was to use the Promoting Action on Research Implementation in Health Systems (PARiHS) framework to evaluate the experiences of implementation of SCI/D MRSA prevention guidelines in VA SCI/D Centers approximately 2-3 years after the guidelines were released.

METHODS: Mixed methods were used across two phases in this study. The first phase included an anonymous, web-based cross-sectional survey administered to providers at all 24 VA SCI/D Centers. The second phase included semi-structured telephone interviews with providers at 9 SCI/D Centers. The PARiHS framework was used as the foundation of both the survey questions and semi-structured interview guide.

RESULTS: The survey was completed by 295 SCI/D providers (43.8 % response rate) from 22 of the 24 SCI/D Centers (91.7 % participation rate). Respondents included nurses (57.3 %), therapists (24.4 %), physicians (11.1 %), physician assistants (3.4 %), and other health care professionals (3.8 %). Approximately 36 % of the SCI/D providers surveyed had not seen, did not remember seeing, or had never heard of the MRSA SCI/D guidelines, whereas 42.3 % of providers reported that the MRSA SCI/D guidelines were fully implemented in their SCI/D Center. Data revealed numerous barriers and facilitators to guideline implementation. Facilitators included enhanced leadership support and provider education, focused guideline dissemination to reach SCI/D providers, and strong perceived evidence supporting the guidelines. Barriers included lack of awareness of the guidelines among physical therapists and physician assistants and challenges in cohorting/isolating MRSA-positive patients and following contact precautions.

CONCLUSIONS: Successful implementation of MRSA infection prevention guidelines in SCI/D settings requires (1) guideline dissemination that reaches the full range of SCI/D providers working in inpatient, outpatient, and other care settings, (2) provider education that is frequent and systematic, (3) strong leadership support, and (4) that barriers unique to the recommendations are addressed. These findings may be used to inform selection of implementation strategies and optimize infection prevention beyond MRSA as well as in other specialty care populations.

Leukemic marrow infiltration reveals a novel role for Egr3 as a potent inhibitor of normal hematopoietic stem cell proliferation

Sat, 12/05/2015 - 9:55pm

Cytopenias resulting from the impaired generation of normal blood cells from hematopoietic precursors are important contributors to morbidity and mortality in patients with leukemia. However, the process by which normal hematopoietic cells are overtaken by emerging leukemia cells and how different subsets of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) are distinctly influenced during leukemic cell infiltration is poorly understood. To investigate these important questions, we used a robust nonirradiated mouse model of human MLL-AF9 leukemia to examine the suppression of HSCs and HPCs during leukemia cell expansion in vivo. Among all the hematopoietic subsets, long-term repopulating HSCs were the least reduced, whereas megakaryocytic-erythroid progenitors were the most significantly suppressed. Notably, nearly all of the HSCs were forced into a noncycling state in leukemic marrow at late stages, but their reconstitution potential appeared to be intact upon transplantation into nonleukemic hosts. Gene expression profiling and further functional validation revealed that Egr3 was a strong limiting factor for the proliferative potential of HSCs. Therefore, this study provides not only a molecular basis for the more tightened quiescence of HSCs in leukemia, but also a novel approach for defining functional regulators of HSCs in disease.

Comparative effectiveness and safety of rituximab versus subsequent anti-tumor necrosis factor therapy in patients with rheumatoid arthritis with prior exposure to anti-tumor necrosis factor therapies in the United States Corrona registry

Sat, 12/05/2015 - 9:55pm

INTRODUCTION: Patients with active rheumatoid arthritis (RA) despite anti-tumor necrosis factor(anti-TNF)agent treatment can switch to either a subsequent anti-TNF agent or a biologic with an alternative mechanism of action, such as rituximab; however, there are limited data available to help physicians decide between these 2 strategies. The objective of this analysis was to examine the effectiveness and safety of rituximab versus a subsequent anti-TNF agent in anti-TNF-experienced patients with RA using clinical practice data from the Corrona registry.

METHODS: Rituximab-naive patients from the Corrona registry with prior exposure to > /=1 anti-TNF agent who initiated rituximab or anti-TNF agents (2/28/2006-10/31/2012) were included. Two cohorts were analyzed: the trimmed population (excluding patients who fell outside the propensity score distribution overlap) and the stratified-matched population (stratified by 1 vs > /=2 anti-TNF agents, then matched based on propensity score). The primary effectiveness outcome was achievement of low disease activity (LDA)/remission (Clinical Disease Activity Index < /=10) at 1 year. Secondary outcomes included achievement of modified American College of Rheumatology (mACR) 20/50/70 responses and meaningful improvement ( > /=0.25) in modified Health Assessment Questionnaire (mHAQ) score at 1 year. New cardiovascular, infectious and cancer events were reported.

RESULTS: Estimates for LDA/remission, mACR response and mHAQ improvement were consistently better for rituximab than for anti-TNF agent users in adjusted analyses. The odds ratio for likelihood of LDA/remission in rituximab versus anti-TNF patients was 1.35 (95 % CI, 0.95-1.91) in the trimmed population and 1.54 (95 % CI, 1.01-2.35) in the stratified-matched population. Rituximab patients were significantly more likely than anti-TNF patients to achieve mACR20/50 and mHAQ improvement in the trimmed population and mACR20 and mHAQ in the stratified-matched population. The rate of new adverse events per 100 patient-years was similar between groups.

CONCLUSIONS: In anti-TNF-experienced patients with RA, rituximab was associated with an increased likelihood of achieving LDA/remission, mACR response and physical function improvement, with a comparable safety profile, versus subsequent anti-TNF agent users.

TRIAL REGISTRATION: ClinicalTrials.gov NCT01402661. Registered 25 July 2011.

Acute symptomatic sinus bradycardia in a woman treated with pulse dose steroids for multiple sclerosis: a case report

Sat, 12/05/2015 - 9:55pm

INTRODUCTION: Sinus bradycardia has been reported after administration of pulse dose steroids, although most cases have occurred in children and are asymptomatic. We report a case of acute symptomatic sinus bradycardia due to pulse dose steroids in a woman with multiple sclerosis. Interestingly, this patient also suffered from inappropriate sinus tachycardia due to autonomic involvement of multiple sclerosis.

CASE PRESENTATION: A 48-year-old Caucasian woman with multiple sclerosis and chronic palpitations due to inappropriate sinus tachycardia was prescribed a 5-day course of intravenous methylprednisolone for treatment of an acute flare. Immediately following the fourth dose of intravenous methylprednisolone, she developed dyspnea, chest heaviness, and lightheadedness. She was referred to the emergency department where an electrocardiogram showed marked sinus bradycardia (40 beats per minute). Initial laboratory test results, including a complete blood count, basic metabolic profile and cardiac biomarkers, were normal. She was admitted for observation on telemetry monitoring. Her heart rate gradually increased and her symptoms resolved. Her outpatient dose of atenolol, taken for symptomatic inappropriate sinus tachycardia, was resumed.

CONCLUSIONS: Our patient's acute symptoms were attributed to symptomatic sinus bradycardia due to pulse dose steroid treatment. Although several theories have been suggested to explain this phenomenon, the exact mechanism still remains unknown. It does not warrant any specific treatment, as it is a self-limiting side effect that resolves after discontinuing steroid infusion. Young patients who are free of any active cardiac conditions can safely be administered pulse dose steroids without monitoring. However, older patients with active cardiac conditions should have heart rate and blood pressure monitoring during infusion. Our patient also suffered from inappropriate sinus tachycardia, a manifestation of autonomic involvement of multiple sclerosis that has not been previously described. This case has implications for the pathogenesis and treatment of dysautonomia in patients with multiple sclerosis.

TCF1 Is Required for the T Follicular Helper Cell Response to Viral Infection

Sat, 12/05/2015 - 9:55pm

T follicular helper (TFH) and T helper 1 (Th1) cells generated after viral infections are critical for the control of infection and the development of immunological memory. However, the mechanisms that govern the differentiation and maintenance of these two distinct lineages during viral infection remain unclear. We found that viral-specific TFH and Th1 cells showed reciprocal expression of the transcriptions factors TCF1 and Blimp1 early after infection, even before the differential expression of the canonical TFH marker CXCR5. Furthermore, TCF1 was intrinsically required for the TFH cell response to viral infection; in the absence of TCF1, the TFH cell response was severely compromised, and the remaining TCF1-deficient TFH cells failed to maintain TFH-associated transcriptional and metabolic signatures, which were distinct from those in Th1 cells. Mechanistically, TCF1 functioned through forming negative feedback loops with IL-2 and Blimp1. Our findings demonstrate an essential role of TCF1 in TFH cell responses to viral infection.

Ultrasonography of adnexal causes of acute pelvic pain in pre-menopausal non-pregnant women

Sat, 12/05/2015 - 9:55pm

Acute-onset pelvic pain is an extremely common symptom in premenopausal women presenting to the emergency department. After excluding pregnancy in reproductive-age women, ultrasonography plays a major role in the prompt and accurate diagnosis of adnexal causes of acute pelvic pain, such as hemorrhagic ovarian cysts, endometriosis, ovarian torsion, and tubo-ovarian abscess. Its availability, relatively low cost, and lack of ionizing radiation make ultrasonography an ideal imaging modality in women of reproductive age. The primary goal of imaging in these patients is to distinguish between adnexal causes of acute pelvic pain that may be managed conservatively or medically, and those requiring emergency/urgent surgical or percutaneous intervention.

TRANSIT - A Software Tool for Himar1 TnSeq Analysis

Sat, 12/05/2015 - 9:55pm

TnSeq has become a popular technique for determining the essentiality of genomic regions in bacterial organisms. Several methods have been developed to analyze the wealth of data that has been obtained through TnSeq experiments. We developed a tool for analyzing Himar1 TnSeq data called TRANSIT. TRANSIT provides a graphical interface to three different statistical methods for analyzing TnSeq data. These methods cover a variety of approaches capable of identifying essential genes in individual datasets as well as comparative analysis between conditions. We demonstrate the utility of this software by analyzing TnSeq datasets of M. tuberculosis grown on glycerol and cholesterol. We show that TRANSIT can be used to discover genes which have been previously implicated for growth on these carbon sources. TRANSIT is written in Python, and thus can be run on Windows, OSX and Linux platforms. The source code is distributed under the GNU GPL v3 license and can be obtained from the following GitHub repository: https://github.com/mad-lab/transit.

Dynamical features of the Plasmodium falciparum ribosome during translation

Sat, 12/05/2015 - 9:55pm

Plasmodium falciparum, the mosquito-transmitted Apicomplexan parasite, causes the most severe form of human malaria. In the asexual blood-stage, the parasite resides within erythrocytes where it proliferates, multiplies and finally spreads to new erythrocytes. Development of drugs targeting the ribosome, the site of protein synthesis, requires specific knowledge of its structure and work cycle, and, critically, the ways they differ from those in the human host. Here, we present five cryo-electron microscopy (cryo-EM) reconstructions of ribosomes purified from P. falciparum blood-stage schizonts at sub-nanometer resolution. Atomic models were built from these density maps by flexible fitting. Significantly, our study has taken advantage of new capabilities of cryo-EM, in visualizing several structures co-existing in the sample at once, at a resolution sufficient for building atomic models. We have discovered structural and dynamic features that differentiate the ribosomes of P. falciparum from those of mammalian system. Prompted by the absence of RACK1 on the ribosome in our and an earlier study we confirmed that RACK1 does not specifically co-purify with the 80S fraction in schizonts. More extensive studies, using cryo-EM methodology, of translation in the parasite will provide structural knowledge that may lead to development of novel anti-malarials.

Palliative care in gynecological cancer

Sat, 12/05/2015 - 9:55pm

According to the WHO definition, “Palliative care is an approach that improves the quality of life of patients and their families facing the problems associated with life-threatening illness, through the prevention and relief of suffering by means of early identification and treatment of other problems, physical, psychosocial and spiritual” [1]. In addition, “Palliative care is required from early in the disease course, can be delivered alongside potentially curative treatment, and continues to include end-of-life or terminal care” [2].

Epigenomics and the structure of the living genome

Sat, 12/05/2015 - 9:55pm

Eukaryotic genomes are packaged into an extensively folded state known as chromatin. Analysis of the structure of eukaryotic chromosomes has been revolutionized by development of a suite of genome-wide measurement technologies, collectively termed "epigenomics." We review major advances in epigenomic analysis of eukaryotic genomes, covering aspects of genome folding at scales ranging from whole chromosome folding down to nucleotide-resolution assays that provide structural insights into protein-DNA interactions. We then briefly outline several challenges remaining and highlight new developments such as single-cell epigenomic assays that will help provide us with a high-resolution structural understanding of eukaryotic genomes.

FTD/ALS-associated poly(GR) protein impairs the Notch pathway and is recruited by poly(GA) into cytoplasmic inclusions

Sat, 12/05/2015 - 9:55pm

C9ORF72 repeat expansion is the most common genetic mutation in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Abnormal dipeptide repeat proteins (DPRs) generated from repeat-associated non-AUG (RAN) translation of repeat-containing RNAs are thought to be pathogenic; however, the mechanisms are unknown. Here we report that (GR)80 and (PR)80 are toxic in neuronal and non-neuronal cells in Drosophila. In contrast to reported shorter poly(GR) forms, (GR)80 is mostly localized throughout the cytosol without detectable accumulation in the nucleolus, accompanied by suppression of Notch signaling and cell loss in the wing. Some Notch target genes are also downregulated in brains and iPSC-derived cortical neurons of C9ORF72 patients. Increased Notch expression largely suppressed (GR)80-induced cell loss in the wing. When co-expressed in Drosophila, HeLa cells, or human neurons, (GA)80 recruited (GR)80 into cytoplasmic inclusions, partially decreasing the toxicity of (GR)80 and restoring Notch signaling in Drosophila. Thus, different DPRs have opposing roles in cell loss and we identify the Notch pathway as one of the receptor signaling pathways that might be compromised in C9ORF72 FTD/ALS.