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Using Mixed Methods to Examine the Role of Veterans' Illness Perceptions on Depression Treatment Utilization and HEDIS Concordance

Wed, 09/28/2016 - 11:25am

BACKGROUND: Although depression screening occurs annually in the Department of Veterans Affairs (VA) primary care, many veterans may not be receiving guideline-concordant depression treatment. OBJECTIVES: To determine whether veterans' illness perceptions of depression may be serving as barriers to guideline-concordant treatment. RESEARCH DESIGN: We used a prospective, observational design involving a mailed questionnaire and chart review data collection to assess depression treatment utilization and concordance with Healthcare Effectiveness Data and Information Set guidelines adopted by the VA. The Self-Regulation Model of Illness Behavior guided the study. SUBJECTS: Veterans who screened positive for a new episode of depression at 3 VA primary care clinics in the US northeast. MEASURES: The Illness Perceptions Questionnaire-Revised, measuring patients' perceptions of their symptoms, cause, timeline, consequences, cure or controllability, and coherence of depression and its symptoms, was our primary measure to calculate veterans' illness perceptions. Treatment utilization was assessed 3 months after the positive depression screen through chart review. Healthcare Effectiveness Data and Information Set (HEDIS) guideline-concordant treatment was determined according to a checklist created for the study. RESULTS: A total of 839 veterans screened positive for a new episode of depression from May 2009-June 2011; 275 (32.8%) completed the survey. Ninety-two (33.9%) received HEDIS guideline-concordant depression treatment. Veterans' illness perceptions of their symptoms, cause, timeline, and controllability of depression predicted receiving guideline-concordant treatment. CONCLUSIONS: Many veterans are not receiving guideline-concordant treatment for depression. HEDIS guideline measures may not be assessing all aspects of quality depression care. Conversations about veterans' illness perceptions and their specific needs are encouraged to ensure that appropriate treatment is achieved.

A novel clinical tool to classify facioscapulohumeral muscular dystrophy phenotypes

Wed, 09/28/2016 - 11:25am

Based on the 7-year experience of the Italian Clinical Network for FSHD, we revised the FSHD clinical form to describe, in a harmonized manner, the phenotypic spectrum observed in FSHD. The new Comprehensive Clinical Evaluation Form (CCEF) defines various clinical categories by the combination of different features. The inter-rater reproducibility of the CCEF was assessed between two examiners using kappa statistics by evaluating 56 subjects carrying the molecular marker used for FSHD diagnosis. The CCEF classifies: (1) subjects presenting facial and scapular girdle muscle weakness typical of FSHD (category A, subcategories A1-A3), (2) subjects with muscle weakness limited to scapular girdle or facial muscles (category B subcategories B1, B2), (3) asymptomatic/healthy subjects (category C, subcategories C1, C2), (4) subjects with myopathic phenotype presenting clinical features not consistent with FSHD canonical phenotype (D, subcategories D1, D2). The inter-rater reliability study showed an excellent concordance of the final four CCEF categories with a kappa equal to 0.90; 95 % CI (0.71; 0.97). Absolute agreement was observed for categories C and D, an excellent agreement for categories A [kappa = 0.88; 95 % CI (0.75; 1.00)], and a good agreement for categories B [kappa = 0.79; 95 % CI (0.57; 1.00)]. The CCEF supports the harmonized phenotypic classification of patients and families. The categories outlined by the CCEF may assist diagnosis, genetic counseling and natural history studies. Furthermore, the CCEF categories could support selection of patients in randomized clinical trials. This precise categorization might also promote the search of genetic factor(s) contributing to the phenotypic spectrum of disease.

Access to New Medications for Hepatitis C for Medicaid Members: A Retrospective Cohort Study

Wed, 09/28/2016 - 11:25am

BACKGROUND: Sofosbuvir (SOF)- or simeprevir (SIM)-containing regimens are highly effective for treating chronic hepatitis C virus (HCV) infection. These regimens, however, are expensive. Most payers have implemented prior authorization (PA) requirements to ensure that patients who can benefit most have priority for these medications. While many Medicaid programs limit access to those with advanced disease or to members who do not have active substance use disorder (SUD), the Massachusetts Medicaid (MassHealth) Primary Care Clinician (PCC) plan does not limit access based on disease severity or presence of SUD. Evaluating PA requests for SOF and/or SIM among MassHealth members will offer a useful example of early uptake among Medicaid members and will identify patient groups who might face barriers to treatment at the provider or patient level.

OBJECTIVES: To (a) evaluate the percentage of MassHealth PCC members with HCV who had a PA request, along with the percentage of requests approved, and (b) identify characteristics associated with PA requests for SOF or SIM among Massachusetts Medicaid (MassHealth) members with HCV.

METHODS: This retrospective cohort study used enrollment, medical claims, and PA request data from MassHealth PCC members from December 6, 2012, to July 31, 2014. The sample included members with 1 or more claims with an ICD-9-CM code for HCV during this time who were continuously enrolled from December 6, 2013, to July 31, 2014. Enrollment and medical claims data for the cohort with HCV were linked to a database containing information collected from PA requests. The overall percentage of members with HCV and a PA request for SOF and/or SIM between December 6, 2013, and July 31, 2014, and the percentage of requests approved were calculated. Chi-square statistics were used to compare demographic and clinical characteristics among members with HCV who did and did not have a request. Logistic regression was used to estimate the strength of associations between patient characteristics and a PA treatment request, adjusting for clinical and demographic variables.

RESULTS: Of 6,849 members identified with HCV, 346 (5.1%) had a PA request for SOF and/or SIM submitted to MassHealth. Compared with members with HCV who did not have a PA request for SOF or SIM, those with a PA request for these new treatments were more likely to be male (P = 0.01), older (P < 0.001), white race (P = 0.04), have standard MassHealth insurance (P = 0.01), and less likely to be homeless (P < 0.001). Members with a PA request were also more likely to have been treated for HCV in the past year and have advanced disease (hepatic decompensation, cirrhosis, or liver transplant) but less likely to have SUD (P < 0.001 for each). Ninety percent of requests for SOF or SIM were approved; few demographic or clinical characteristics were associated with approval. In adjusted analyses, predictors of PA request were aged 50-64 years (odds ratio (OR) = 2.0, 95% CI = 1.1-3.7 vs. aged < 30 years); hepatic decompensation (OR = 1.6, 95% CI = 1.2-2.3); cirrhosis (OR = 3.0, 95% CI = 2.2-4.1); liver transplant (OR = 3.0, 95% CI = 1.4-6.5); substance use (OR = 0.6, 95% CI = 0.5-0.8); recent HCV treatment (OR = 1.6, 95% CI = 1.0-2.6); comorbidity (OR = 0.95, 95% CI = 0.91-0.98) for 1-unit increase in Diagnostic Cost Group score; and care at a hospital outpatient department (OR = 2.0, 95% CI = 1.2-3.2 vs. group practice).

CONCLUSIONS: Antiviral treatment with SOF and/or SIM was requested for a relatively small proportion of MassHealth members with HCV, with nearly all approved. Prescriber prioritization or patient barriers to care, rather than the PA process, determined access to treatment in this Medicaid population. Support may be needed to ensure patients with SUD benefit from advances in HCV treatment.

Preparing Future Leaders: An Integrated Quality Improvement Residency Curriculum

Wed, 09/28/2016 - 11:25am

BACKGROUND AND OBJECTIVES: The Accreditation Council for Graduate Medical Education (ACGME) has recognized the importance of quality improvement (QI) training and requires that accredited residencies in all specialties demonstrate that residents are "integrated and actively participate in interdisciplinary clinical quality improvement and patient safety activities." However, competing demands in residency training may make this difficult to accomplish. The study's objective is to develop and evaluate a longitudinal curriculum that meets the ACGME requirement for QI and patient safety training and links to patient-centered medical home (PCMH) practices.

METHODS: Residents in the Worcester Family Medicine Residency (WFMR) participated in a faculty-developed quality improvement curriculum that included web-based tutorials, quality improvement projects, and small-group sessions across all 3 years of residency. They completed self-evaluations of knowledge and use of curricular activities annually and at graduation, and comparisons were made between two graduating classes, as well as comparison of end of PGY2 to end of PGY3 for one class.

RESULTS: Graduating residents who completed the full 3 years of the curriculum rated themselves as significantly more skilled in nine of 15 areas assessed at end of residency compared to after PGY2 and reported confidence in providing future leadership in a focus group. Five areas were also rated significantly higher than prior-year residents.

CONCLUSIONS: Involving family medicine residents in a longitudinal curriculum with hands-on practice in implementing QI, patient safety, and chronic illness management activities that are inclusive of PCMH goals increased their self-perceived skills and leadership ability to implement these new and emerging evidence-based practices in primary care.

Small Molecule Inhibitor of CBFbeta-RUNX Binding for RUNX Transcription Factor Driven Cancers

Wed, 09/28/2016 - 11:25am

Transcription factors have traditionally been viewed with skepticism as viable drug targets, but they offer the potential for completely novel mechanisms of action that could more effectively address the stem cell like properties, such as self-renewal and chemo-resistance, that lead to the failure of traditional chemotherapy approaches. Core binding factor is a heterodimeric transcription factor comprised of one of 3 RUNX proteins (RUNX1-3) and a CBFbeta binding partner. CBFbeta enhances DNA binding of RUNX subunits by relieving auto-inhibition. Both RUNX1 and CBFbeta are frequently mutated in human leukemia. More recently, RUNX proteins have been shown to be key players in epithelial cancers, suggesting the targeting of this pathway could have broad utility. In order to test this, we developed small molecules which bind to CBFbeta and inhibit its binding to RUNX. Treatment with these inhibitors reduces binding of RUNX1 to target genes, alters the expression of RUNX1 target genes, and impacts cell survival and differentiation. These inhibitors show efficacy against leukemia cells as well as basal-like (triple-negative) breast cancer cells. These inhibitors provide effective tools to probe the utility of targeting RUNX transcription factor function in other cancers.

The changing landscape of biosimilars in rheumatology

Wed, 09/28/2016 - 11:25am

Biosimilars remain a hot topic in rheumatology, and some physicians are cautious about their application in the real world. With many products coming to market and a wealth of guidelines and recommendations concerning their use, there is a need to understand the changing landscape and the real clinical and health-economic potential offered by these agents. Notably, rheumatologists will be at the forefront of the use of biosimilar monoclonal antibodies/soluble receptors. Biosimilars offer cost savings and health gains for our patients and will play an important role in treating rheumatic diseases. We hope that these lower costs will compensate for inequities in access to therapy based on economic differences across countries. Since approved biosimilars have already demonstrated highly similar efficacy, it will be most important to establish pharmacovigilance databases across countries that are adequate to monitor long-term safety after marketing approval.

Cancer of the uterus and treatment of stress incontinence: a pilot study

Wed, 09/28/2016 - 11:25am

The purpose of this pilot study was to determine whether women with early-stage endometrial cancer could be screened for stress urinary incontinence (SUI) at their initial gynecologic oncology visit and referred to a urogynecologist for concurrent treatment of their endometrial cancer and SUI.

CPEB1 mediates epithelial-to-mesenchyme transition and breast cancer metastasis

Wed, 09/28/2016 - 11:25am

In mouse mammary epithelial cells, cytoplasmic polyadenylation element binding protein 1 (CPEB1) mediates the apical localization of ZO-1 mRNA, which encodes a critical tight junction component. In mice lacking CPEB1 and in cultured cells from which CPEB has been depleted, randomly distributed ZO-1 mRNA leads to the loss of cell polarity. We have investigated whether this diminution of polarity results in an epithelial-to-mesenchyme (EMT) transition and possible increased metastatic potential. Here, we show that CPEB1-depleted mammary epithelial cells alter their gene expression profile in a manner consistent with an EMT and also become motile, which are made particularly robust when cells are treated with transforming growth factor-beta, an enhancer of EMT. CPEB1-depleted mammary cells become metastatic to the lung following injection into mouse fat pads while ectopically expressed CPEB1 prevents metastasis. Surprisingly, CPEB1 depletion causes some EMT/metastasis-related mRNAs to have shorter poly(A) tails while other mRNAs to have longer poly(A) tails. Matrix metalloproteinase 9 (MMP9) mRNA, which encodes a metastasis-promoting factor, undergoes poly(A) lengthening and enhanced translation upon CPEB reduction. Moreover, in human breast cancer cells that become progressively more metastatic, CPEB1 is reduced while MMP9 becomes more abundant. These data suggest that at least in part, CPEB1 regulation of MMP9 mRNA expression mediates metastasis of breast cancer cells.

Standardizing disease-specific quality of life measures across multiple chronic conditions: development and initial evaluation of the QOL Disease Impact Scale (QDIS(R))

Wed, 09/28/2016 - 11:25am

BACKGROUND: To document the development and evaluation of the Quality of life Disease Impact Scale (QDIS(R)), a measure that standardizes item content and scoring across chronic conditions and provides a summary, norm-based QOL impact score for each disease.

METHODS: A bank of 49 disease impact items was constructed from previously-used descriptions of health impact to represent ten frequently-measured quality of life (QOL) content areas and operational definitions successfully utilized in generic QOL surveys. In contrast to health in general, all items were administered with attribution to a specific disease (osteoarthritis, rheumatoid arthritis, angina, myocardial infarction, congestive heart failure, chronic kidney disease (CKD), diabetes, asthma, or COPD). Responses from 5418 adults were analyzed as five disease groups: arthritis, cardiovascular, CKD, diabetes, and respiratory. Unidimensionality, item parameter and scale-level invariance, reliability, validity and responsiveness to change during 9-month follow-up were evaluated by disease group and for all groups combined using multi-group confirmatory factor analysis (MGCFA), item response theory (IRT) and analysis of variance methods. QDIS was normed in an independent chronically ill US population sample (N = 4120).

RESULTS: MGCFA confirmed a 1-factor model, justifying a summary score estimated using equal parameters for each item across disease groups. In support of standardized IRT-based scoring, correlations were very high between disease-specific and standardized IRT item slopes (r = 0.88-0.96), thresholds (r = 0.93-0.99) and person-level scores (r > /= 0.99). Internal consistency, test-retest and person-level IRT reliability were consistently satisfactory across groups. In support of interpreting QDIS as a disease-specific measure, in comparison with generic measures, QDIS consistently discriminated markedly better across disease severity levels, correlated higher with other disease-specific measures in cross-sectional tests, and was more responsive in comparisons of groups with better, same or worse evaluations of disease-specific outcomes at the 9-month follow-up.

CONCLUSIONS: Standardization of content and scoring across diseases was shown to be justified psychometrically and enabled the first summary measure of disease-specific QOL impact normed in the chronically ill population. This disease-specific approach substantially improves discriminant validity and responsiveness over generic measures and provides a basis for better understanding the relative QOL impact of multiple chronic conditions in research and clinical practice.

Health Information Brokers in the General Population: An Analysis of the Health Information National Trends Survey 2013-2014

Wed, 09/28/2016 - 11:25am

BACKGROUND: Health information exchanged between friends or family members can influence decision making, both for routine health questions and for serious health issues. A health information broker is a person to whom friends and family turn for advice or information on health-related topics. Characteristics and online behaviors of health information brokers have not previously been studied in a national population.

OBJECTIVE: The objective of this study was to examine sociodemographic characteristics, health information seeking behaviors, and other online behaviors among health information brokers.

METHODS: Data from the Health Information National Trends Survey (2013-2014; n=3142) were used to compare brokers with nonbrokers. Modified Poisson regression was used to examine the relationship between broker status and sociodemographics and online information seeking.

RESULTS: Over half (54.8%) of the respondents were consulted by family or friends for advice or information on health topics (ie, they acted as health information brokers). Brokers represented 54.1% of respondents earning < $20,000 yearly and 56.5% of respondents born outside the United States. Women were more likely to be brokers (PR 1.34, 95% CI 1.23-1.47) as were those with education past high school (PR 1.42, CI 1.22-1.65). People aged > /=75 were less likely to be brokers as compared to respondents aged 35-49 (PR 0.81, CI 0.67-0.99). Brokers used the Internet more frequently for a variety of online behaviors such as seeking health information, creating and sharing online content, and downloading health information onto a mobile device; and also reported greater confidence in obtaining health information online.

CONCLUSIONS: More than 50% of adults who responded to this national survey, including those with low income and those born abroad, were providing health information or advice to friends and family. These individuals may prove to be effective targets for initiatives supporting patient engagement and disease management, and may also be well-positioned within their respective social networks to propagate health messages.

Septate Junction Proteins Play Essential Roles in Morphogenesis Throughout Embryonic Development in Drosophila

Wed, 09/28/2016 - 11:25am

The septate junction (SJ) is the occluding junction found in the ectodermal epithelia of invertebrate organisms, and is essential to maintain chemically distinct compartments in epithelial organs, to provide the blood-brain barrier in the nervous system, and to provide an important line of defense against invading pathogens. More than 20 genes have been identified to function in the establishment or maintenance of SJs in Drosophila melanogaster Numerous studies have demonstrated the cell biological function of these proteins in establishing the occluding junction, whereas very few studies have examined further developmental roles for them. Here we examined embryos with mutations in nine different core SJ genes and found that all nine result in defects in embryonic development as early as germ band retraction, with the most penetrant defect observed in head involution. SJ genes are also required for cell shape changes and cell rearrangements that drive the elongation of the salivary gland during midembryogenesis. Interestingly, these developmental events occur at a time prior to the formation of the occluding junction, when SJ proteins localize along the lateral membrane and have not yet coalesced into the region of the SJ. Together, these observations reveal an underappreciated role for a large group of SJ genes in essential developmental events during embryogenesis, and suggest that the function of these proteins in facilitating cell shape changes and rearrangements is independent of their role in the occluding junction.

ER stress in temozolomide-treated glioblastomas interferes with DNA repair and induces apoptosis

Wed, 09/28/2016 - 11:25am

Glioblastoma multiforme (GBM) is a deadly grade IV brain tumor. Radiation in combination with temozolomide (TMZ), the current chemotherapeutic for GBMs, only provides 12-14 months survival post diagnosis. Because GBMs are dependent on both activation of the DNA damage pathway and the endoplasmic reticulum (ER) stress response, we asked if a novel ER stress inducing agent, JLK1486, increases the efficacy of TMZ. We found that the combination of TMZ+JLK1486 resulted in decreased proliferation in a panel of adherent GBM cells lines and reduced secondary sphere formation in non-adherent and primary lines. Decreased proliferation correlated with increased cell death due to apoptosis. We found prolonged ER stress in TMZ+JLK1486 treated cells that resulted in sustained activation of the unfolded protein response (UPR) through increased levels of BiP, ATF4, and CHOP. In addition, TMZ+JLK1486 treatment caused decreased RAD51 levels, impairing DNA damage repair. Furthermore, we found delayed time to tumor doubling in TMZ+JLK1486 treated mice. Our data shows that the addition of JLK1486 to TMZ increases the efficaciousness of the treatment by decreasing proliferation and inducing cell death. We propose increased cell death is due to two factors. One, prolonged ER stress driving the expression of the pro-apoptotic transcription factor CHOP, and, second, unresolved DNA double strand breaks, due to decreased RAD51 levels. The combination of TMZ+JLK1486 is a potential novel therapeutic combination and suggests an inverse relationship between unresolved ER stress and the DNA damage response pathway.

Auditory Hallucinations and the Brain's Resting-State Networks: Findings and Methodological Observations

Wed, 09/28/2016 - 11:24am

In recent years, there has been increasing interest in the potential for alterations to the brain's resting-state networks (RSNs) to explain various kinds of psychopathology. RSNs provide an intriguing new explanatory framework for hallucinations, which can occur in different modalities and population groups, but which remain poorly understood. This collaboration from the International Consortium on Hallucination Research (ICHR) reports on the evidence linking resting-state alterations to auditory hallucinations (AH) and provides a critical appraisal of the methodological approaches used in this area. In the report, we describe findings from resting connectivity fMRI in AH (in schizophrenia and nonclinical individuals) and compare them with findings from neurophysiological research, structural MRI, and research on visual hallucinations (VH). In AH, various studies show resting connectivity differences in left-hemisphere auditory and language regions, as well as atypical interaction of the default mode network and RSNs linked to cognitive control and salience. As the latter are also evident in studies of VH, this points to a domain-general mechanism for hallucinations alongside modality-specific changes to RSNs in different sensory regions. However, we also observed high methodological heterogeneity in the current literature, affecting the ability to make clear comparisons between studies. To address this, we provide some methodological recommendations and options for future research on the resting state and hallucinations.

Reassessing the role of the NLRP3 inflammasome during pathogenic influenza A virus infection via temporal inhibition

Wed, 09/28/2016 - 11:24am

The inflammasome NLRP3 is activated by pathogen associated molecular patterns (PAMPs) during infection, including RNA and proteins from influenza A virus (IAV). However, chronic activation by danger associated molecular patterns (DAMPs) can be deleterious to the host. We show that blocking NLRP3 activation can be either protective or detrimental at different stages of lethal influenza A virus (IAV). Administration of the specific NLRP3 inhibitor MCC950 to mice from one day following IAV challenge resulted in hypersusceptibility to lethality. In contrast, delaying treatment with MCC950 until the height of disease (a more likely clinical scenario) significantly protected mice from severe and highly virulent IAV-induced disease. These findings identify for the first time that NLRP3 plays a detrimental role later in infection, contributing to IAV pathogenesis through increased cytokine production and lung cellular infiltrates. These studies also provide the first evidence identifying NLRP3 inhibition as a novel therapeutic target to reduce IAV disease severity.

IL-2 and IL-6 cooperate to enhance the generation of influenza-specific CD8 T cells responding to live influenza virus in aged mice and humans

Wed, 09/28/2016 - 11:24am

An age-related decline in cytolytic activity has been described in CD8+ T cells and we have previously shown that the poor CD8+ effector T cell responses to influenza A/H3N2 challenge result from a decline in the proportion and function of these cytolytic T lymphocytes (CTL). Here, we describe that addition of exogenous cytokines to influenza-stimulated PBMC from both aged mice and humans, enhances the generation of influenza specific CD8 CTL by increasing their proliferation and survival. Our data show that the addition of IL-2 and IL-6 to splenocytes from mice previously infected with influenza virus restores the aged CD8+ T cell response to that observed in young mice. In humans, IL-2 plus IL-6 also reduces the proportion of apoptotic effector CD8+ T cells to levels resembling those of younger adults. In HLA-A2+ donors, MHC Class I tetramer staining showed that adding both exogenous IL-2 and IL-6 resulted in greater differentiation into influenza-specific effector CD8+ T cells. Since this effect of IL-2/IL-6 supplementation can be reproduced with the addition of Toll-like receptor agonists, it may be possible to exploit this mechanism and design new vaccines to improve the CD8 T cell response to influenza vaccination in older adults.

Type I Interferon Induction by Neisseria gonorrhoeae: Dual Requirement of Cyclic GMP-AMP Synthase and Toll-like Receptor 4

Wed, 09/28/2016 - 11:24am

The innate immune system is the first line of defense against Neisseria gonorrhoeae (GC). Exposure of cells to GC lipooligosaccharides induces a strong immune response, leading to type I interferon (IFN) production via TLR4/MD-2. In addition to living freely in the extracellular space, GC can invade the cytoplasm to evade detection and elimination. Double-stranded DNA introduced into the cytosol binds and activates the enzyme cyclic-GMP-AMP synthase (cGAS), which produces 2'3'-cGAMP and triggers STING/TBK-1/IRF3 activation, resulting in type I IFN expression. Here, we reveal a cytosolic response to GC DNA that also contributes to type I IFN induction. We demonstrate that complete IFN-beta induction by live GC depends on both cGAS and TLR4. Type I IFN is detrimental to the host, and dysregulation of iron homeostasis genes may explain lower bacteria survival in cGAS(-/-) and TLR4(-/-) cells. Collectively, these observations reveal cooperation between TLRs and cGAS in immunity to GC infection.

CYLD Proteolysis Protects Macrophages from TNF-Mediated Auto-necroptosis Induced by LPS and Licensed by Type I IFN

Wed, 09/28/2016 - 11:24am

Tumor necrosis factor (TNF) induces necroptosis, a RIPK3/MLKL-dependent form of inflammatory cell death. In response to infection by Gram-negative bacteria, multiple receptors on macrophages, including TLR4, TNF, and type I IFN receptors, are concurrently activated, but it is unclear how they crosstalk to regulate necroptosis. We report that TLR4 activates CASPASE-8 to cleave and remove the deubiquitinase cylindromatosis (CYLD) in a TRIF- and RIPK1-dependent manner to disable necroptosis in macrophages. Inhibiting CASPASE-8 leads to CYLD-dependent necroptosis caused by the TNF produced in response to TLR4 ligation. While lipopolysaccharides (LPS)-induced necroptosis was abrogated in Tnf(-/-) macrophages, a soluble TNF antagonist was not able to do so in Tnf(+/+) macrophages, indicating that necroptosis occurs in a cell-autonomous manner. Surprisingly, TNF-mediated auto-necroptosis of macrophages requires type I IFN, which primes the expression of key necroptosis-signaling molecules, including TNFR2 and MLKL. Thus, the TNF necroptosis pathway is regulated by both negative and positive crosstalk.

A cytoplasmic peptidoglycan amidase homologue controls mycobacterial cell wall synthesis

Wed, 09/28/2016 - 11:24am

Regulation of cell wall assembly is essential for bacterial survival and contributes to pathogenesis and antibiotic tolerance in Mycobacterium tuberculosis (Mtb). However, little is known about how the cell wall is regulated in stress. We found that CwlM, a protein homologous to peptidoglycan amidases, coordinates peptidoglycan synthesis with nutrient availability. Surprisingly, CwlM is sequestered from peptidoglycan (PG) by localization in the cytoplasm, and its enzymatic function is not essential. Rather, CwlM is phosphorylated and associates with MurA, the first enzyme in PG precursor synthesis. Phosphorylated CwlM activates MurA ~30 fold. CwlM is dephosphorylated in starvation, resulting in lower MurA activity, decreased cell wall metabolism, and increased tolerance to multiple antibiotics. A phylogenetic analysis of cwlM implies that localization in the cytoplasm drove the evolution of this factor. We describe a system that controls cell wall metabolism in response to starvation, and show that this regulation contributes to antibiotic tolerance.

Cholesterol-Independent SREBP-1 Maturation Is Linked to ARF1 Inactivation

Wed, 09/28/2016 - 11:24am

Lipogenesis requires coordinated expression of genes for fatty acid, phospholipid, and triglyceride synthesis. Transcription factors, such as SREBP-1 (Sterol regulatory element binding protein), may be activated in response to feedback mechanisms linking gene activation to levels of metabolites in the pathways. SREBPs can be regulated in response to membrane cholesterol and we also found that low levels of phosphatidylcholine (a methylated phospholipid) led to SBP-1/SREBP-1 maturation in C. elegans or mammalian models. To identify additional regulatory components, we performed a targeted RNAi screen in C. elegans, finding that both lpin-1/Lipin 1 (which converts phosphatidic acid to diacylglycerol) and arf-1.2/ARF1 (a GTPase regulating Golgi function) were important for low-PC activation of SBP-1/SREBP-1. Mechanistically linking the major hits of our screen, we find that limiting PC synthesis or LPIN1 knockdown in mammalian cells reduces the levels of active GTP-bound ARF1. Thus, changes in distinct lipid ratios may converge on ARF1 to increase SBP-1/SREBP-1 activity.

Levels of Ycg1 Limit Condensin Function during the Cell Cycle

Wed, 09/28/2016 - 11:24am

During mitosis chromosomes are condensed to facilitate their segregation, through a process mediated by the condensin complex. Although several factors that promote maximal condensin activity during mitosis have been identified, the mechanisms that downregulate condensin activity during interphase are largely unknown. Here, we demonstrate that Ycg1, the Cap-G subunit of budding yeast condensin, is cell cycle-regulated with levels peaking in mitosis and decreasing as cells enter G1 phase. This cyclical expression pattern is established by a combination of cell cycle-regulated transcription and constitutive degradation. Interestingly, overexpression of YCG1 and mutations that stabilize Ycg1 each result in delayed cell-cycle entry and an overall proliferation defect. Overexpression of no other condensin subunit impacts the cell cycle, suggesting that Ycg1 is limiting for condensin complex formation. Consistent with this possibility, we find that levels of intact condensin complex are reduced in G1 phase compared to mitosis, and that increased Ycg1 expression leads to increases in both levels of condensin complex and binding to chromatin in G1. Together, these results demonstrate that Ycg1 levels limit condensin function in interphase cells, and suggest that the association of condensin with chromosomes must be reduced following mitosis to enable efficient progression through the cell cycle.