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Publications in Health Sciences by NOMIS researchers

Amyloid proteotoxicity initiates an inflammatory response blocked by cannabinoids

NOMIS Researcher(s)

Published in

January 1, 2016

The beta amyloid (Aβ) and other aggregating proteins in the brain increase with age and are frequently found within neurons. The mechanistic relationship between intracellular amyloid, aging and neurodegeneration is not, however, well understood. We use a proteotoxicity model based upon the inducible expression of Aβ in a human central nervous system nerve cell line to characterize a distinct form of nerve cell death caused by intracellular Aβ. It is shown that intracellular Aβ initiates a toxic inflammatory response leading to the cell’s demise. Aβ induces the expression of multiple proinflammatory genes and an increase in both arachidonic acid and eicosanoids, including prostaglandins that are neuroprotective and leukotrienes that potentiate death. Cannabinoids such as tetrahydrocannabinol stimulate the removal of intraneuronal Aβ, block the inflammatory response, and are protective. Altogether these data show that there is a complex and likely autocatalytic inflammatory response within nerve cells caused by the accumulation of intracellular Aβ, and that this early form of proteotoxicity can be blocked by the activation of cannabinoid receptors.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1038/npjamd.2016.12

Nuclear envelope rupture is induced by actin-based nucleus confinement

NOMIS Researcher(s)

Published in

January 1, 2016

Repeated rounds of nuclear envelope (NE) rupture and repair have been observed in laminopathy and cancer cells and result in intermittent loss of nucleus compartmentalization. Currently, the causes of NE rupture are unclear. Here, we show that NE rupture in cancer cells relies on the assembly of contractile actin bundles that interact with the nucleus via the linker of nucleoskeleton and cytoskeleton (LINC) complex. We found that the loss of actin bundles or the LINC complex did not rescue nuclear lamina defects, a previously identified determinant of nuclear membrane stability, but did decrease the number and size of chromatin hernias. Finally, NE rupture inhibition could be rescued in cells treated with actin-depolymerizing drugs by mechanically constraining nucleus height. These data suggest a model of NE rupture where weak membrane areas, caused by defects in lamina organization, rupture because of an increase in intranuclear pressure from actin-based nucleus confinement.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1083/jcb.201603053

Birt–Hogg–Dubé syndrome: novel FLCN frameshift deletion in daughter and father with renal cell carcinomas

NOMIS Researcher(s)

Published in

January 1, 2016

Germline mutation of the FLCN gene causes Birt–Hogg–Dubé syndrome (BHD), a rare autosomal dominant condition characterized by skin fibrofolliculomas, lung cysts, spontaneous pneumothorax and renal tumours. We identified a hitherto unreported pathogenic FLCN frameshift deletion c.563delT (p.Phe188Serfs*35) in a family of a 46-year-old woman presented with macrohematuria due to bilateral chromophobe renal carcinomas. A heritable renal cancer was suspected due to the bilaterality of the tumour and as the father of this woman had suffered from renal cancer. Initially, however, BHD was overlooked by the medical team despite the highly suggestive clinical presentation. We assume that BHD is underdiagnosed, at least partially, due to low awareness of this variable condition and to insufficient use of appropriate genetic testing. Our study indicates that BHD and FLCN testing should be routinely considered in patients with positive family or personal history of renal tumours. In addition, we demonstrate how patients and their families can play a driving role in initiating genetic diagnosis, presymptomatic testing of at-risk relatives, targeted disease management, and genetic counselling of rare diseases such as BHD.

Research field(s)
Health Sciences, Clinical Medicine, Oncology & Carcinogenesis

DOI
10.1007/s10689-015-9837-5

Depletion of fat-resident T reg cells prevents age-associated insulin resistance

NOMIS Researcher(s)

Published in

December 3, 2015

Age-associated insulin resistance (IR) and obesity-associated IR are two physiologically distinct forms of adult-onset diabetes. While macrophage-driven inflammation is a core driver of obesity-associated IR, the underlying mechanisms of the obesity-independent yet highly prevalent age-associated IR are largely unexplored. Here we show, using comparative adipo-immune profiling in mice, that fat-resident regulatory T cells, termed fT reg cells, accumulate in adipose tissue as a function of age, but not obesity. Supporting the existence of two distinct mechanisms underlying IR, mice deficient in fT reg cells are protected against age-associated IR, yet remain susceptible to obesity-associated IR and metabolic disease. By contrast, selective depletion of fT reg cells via anti-ST2 antibody treatment increases adipose tissue insulin sensitivity. These findings establish that distinct immune cell populations within adipose tissue underlie ageing- and obesity-associated IR, and implicate fT reg cells as adipo-immune drivers and potential therapeutic targets in the treatment of age-associated IR.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1038/nature16151

The TAM receptor Mertk protects against neuroinvasive viral infection by maintaining blood-brain barrier integrity

NOMIS Researcher(s)

Published in

December 1, 2015

The TAM receptors Tyro3, Axl and Mertk are receptor tyrosine kinases that dampen host innate immune responses following engagement with their ligands Gas6 and Protein S, which recognize phosphatidylserine on apoptotic cells. In a form of apoptotic mimicry, many enveloped viruses display phosphatidylserine on the outer leaflet of their membranes, enabling TAM receptor activation and downregulation of antiviral responses. Accordingly, we hypothesized that a deficiency of TAM receptors would enhance antiviral responses and protect against viral infection. Unexpectedly, mice lacking Mertk and/or Axl, but not Tyro3, exhibited greater vulnerability to infection with neuroinvasive West Nile and La Crosse encephalitis viruses. This phenotype was associated with increased blood-brain barrier permeability, which enhanced virus entry into and infection of the brain. Activation of Mertk synergized with interferon-β to tighten cell junctions and prevent virus transit across brain microvascular endothelial cells. Because TAM receptors restrict pathogenesis of neuroinvasive viruses, these findings have implications for TAM antagonists that are currently in clinical development.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1038/nm.3974

T cell receptor dwell times control the kinase activity of Zap70

NOMIS Researcher(s)

Published in

August 19, 2015

Kinase recruitment to membrane receptors is essential for signal transduction. However, the underlying regulatory mechanisms are poorly understood. We investigated how conformational changes control T cell receptor (TCR) association and activity of the kinase Zap70. Structural analysis showed that TCR binding or phosphorylation of Zap70 triggers a transition from a closed, autoinhibited conformation to an open conformation. Using Zap70 mutants with defined conformations, we found that TCR dwell times controlled Zap70 activity. The closed conformation minimized TCR dwell times and thereby prevented activation by membrane-associated kinases. Parallel recruitment of coreceptor-associated Lck kinase to the TCR ensured Zap70 phosphorylation and stabilized Zap70 TCR binding. Our study suggests that the dynamics of cytosolic enzyme recruitment to the plasma membrane regulate the activity and function of receptors lacking intrinsic catalytic activity.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1038/ni.3231

The CREB/CRTC2 pathway modulates autoimmune disease by promoting Th17 differentiation

NOMIS Researcher(s)

Published in

June 2, 2015

Following their activation in response to inflammatory signals, innate immune cells secrete T-cell-polarizing cytokines that promote the differentiation of naive CD4 T cells into T helper (Th) cell subsets. Among these, Th17 cells play a prominent role in the development of a number of autoimmune diseases. Although regarded primarily as an immunosuppressant signal, cAMP has been found to mediate pro-inflammatory effects of macrophage-derived prostaglandin E2 (PGE 2) on Th17 cells. Here we show that PGE 2 enhances Th17 cell differentiation via the activation of the CREB co-activator CRTC2. Following its dephosphorylation, CRTC2 stimulates the expression of the cytokines IL-17A and IL-17F by binding to CREB over both promoters. CRTC2-mutant mice have decreased Th17 cell numbers, and they are protected from experimental autoimmune encephalitis, a model for multiple sclerosis. Our results suggest that small molecule inhibitors of CRTC2 may provide therapeutic benefit to individuals with autoimmune disease.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1038/ncomms8216

Regulatory T cell identity: Formation and maintenance

NOMIS Researcher(s)

Published in

June 1, 2015

T regulatory (Treg) cells are central to the maintenance of immune homeostasis. The transcription factor forkhead box P3 (Foxp3) is essential for specifying the Treg cell lineage during development, and continued expression of Foxp3 in mature Treg cells is necessary for suppressive function. Loss of Foxp3 expression in Treg cells is associated with autoimmune pathology. Here, we review recent insights into the mechanisms that maintain Treg cell stability and function, and place these findings within the broader understanding of mechanisms that establish Treg cell identity during development. We integrate emerging principles in Treg cell lineage maintenance with the mechanisms that allow Treg cells to sense and respond to varied inflammatory environments, and outline important areas of future inquiry in this context.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1016/j.it.2015.04.006

Mer receptor tyrosine kinase mediates both tethering and phagocytosis of apoptotic cells

NOMIS Researcher(s)

Published in

January 1, 2015

Billions of inflammatory leukocytes die and are phagocytically cleared each day. This regular renewal facilitates the normal termination of inflammatory responses, suppressing pro-inflammatory mediators and inducing their anti-inflammatory counterparts. Here we investigate the role of the receptor tyrosine kinase (RTK) Mer and its ligands Protein S and Gas6 in the initial recognition and capture of apoptotic cells (ACs) by macrophages. We demonstrate extremely rapid binding kinetics of both ligands to phosphatidylserine (PtdSer)-displaying ACs, and show that ACs can be co-opsonized with multiple PtdSer opsonins.We further show that macrophage phagocytosis of ACs opsonized with Mer ligands can occur independently of a requirement for αV integrins. Finally, we demonstrate a novel role for Mer in the tethering of ACs to the macrophage surface, and show that Mer-mediated tethering and subsequent AC engulfment can be distinguished by their requirement for Mer kinase activity. Our results identify Mer as a receptor uniquely capable of both tethering ACs to the macrophage surface and driving their subsequent internalization.

Research field(s)
Health Sciences, Biomedical Research, Biochemistry & Molecular Biology

DOI
10.1038/cddis.2015.18

Characterizing new fluorescent tools for studying 5-HT3 receptor pharmacology

NOMIS Researcher(s)

Published in

January 1, 2015

The pharmacological characterization of ligands depends upon the ability to accurately measure their binding properties. Fluorescence provides an alternative to more traditional approaches such as radioligand binding. Here we describe the binding and spectroscopic properties of eight fluorescent 5-HT3 receptor ligands. These were tested on purified receptors, expressed receptors on live cells, or in vivo. All compounds had nanomolar affinities with fluorescent properties extending from blue to near infra-red emission. A fluorescein-derivative had the highest affinity as measured by fluorescence polarization (FP; 1.14 nM), flow cytometry (FC; 3.23 nM) and radioligand binding (RB; 1.90 nM). Competition binding with unlabeled 5-HT3 receptor agonists (5-HT, mCPBG, quipazine) and antagonists (granisetron, palonosetron, tropisetron) yielded similar affinities in all three assays. When cysteine substitutions were introduced into the 5-HT3 receptor binding site the same changes in binding affinity were seen for both granisetron and the fluorescein-derivative, suggesting that they both adopt orientations that are consistent with co-crystal structures of granisetron with a homologous protein (5HTBP). As expected, in vivo live imaging in anaesthetized mice revealed staining in the abdominal cavity in intestines, but also in salivary glands. The unexpected presence of 5-HT3 receptors in mouse salivary glands was confirmed by Western blots. Overall, these results demonstrate the wide utility of our new high-affinity fluorescently-labeled 5-HT3 receptor probes, ranging from in vitro receptor pharmacology, including FC and FP ligand competition, to live imaging of 5-HT3 expressing tissues.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1016/j.neuropharm.2014.11.007

Sulfonation pathway inhibitors block reactivation of latent HIV-1

NOMIS Researcher(s)

Published in

December 1, 2014

Long-lived pools of latently infected cells are a significant barrier to the development of a cure for HIV-1 infection. A better understanding of the mechanisms of reactivation from latency is needed to facilitate the development of novel therapies that address this problem. Here we show that chemical inhibitors of the sulfonation pathway prevent virus reactivation, both in latently infected J-Lat and U1 cell lines and in a primary human CD4+ T cell model of latency. In each of these models, sulfonation inhibitors decreased transcription initiation from the HIV-1 promoter. These inhibitors block transcription initiation at a step that lies downstream of nucleosome remodeling and affects RNA polymerase II recruitment to the viral promoter. These results suggest that the sulfonation pathway acts by a novel mechanism to regulate efficient virus transcription initiation during reactivation from latency, and further that augmentation of this pathway could be therapeutically useful.

Research field(s)
Health Sciences, Biomedical Research, Virology

DOI
10.1016/j.virol.2014.08.016

An empirically derived composite cognitive test score with improved power to track and evaluate treatments for preclinical Alzheimer’s disease

NOMIS Researcher(s)

Published in

November 1, 2014

Background There is growing interest in the evaluation of preclinical Alzheimer’s disease (AD) treatments. As a result, there is a need to identify a cognitive composite that is sensitive to track preclinical AD decline to be used as a primary endpoint in treatment trials. Methods Longitudinal data from initially cognitively normal, 70- to 85-year-old participants in three cohort studies of aging and dementia from the Rush Alzheimer’s Disease Center were examined to empirically define a composite cognitive endpoint that is sensitive to detect and track cognitive decline before the onset of cognitive impairment. The mean-to-standard deviation ratios (MSDRs) of change over time were calculated in a search for the optimal combination of cognitive tests/subtests drawn from the neuropsychological battery in cognitively normal participants who subsequently progressed to clinical stages of AD during 2- and 5-year periods, using data from those who remained unimpaired during the same period to correct for aging and practice effects. Combinations that performed well were then evaluated for representation of relevant cognitive domains, robustness across individual years before diagnosis, and occurrence of selected items within top performing combinations. Results The optimal composite cognitive test score comprised seven cognitive tests/subtests with an MSDR = 0.964. By comparison, the most sensitive individual test score was Logical Memory Delayed Recall with an MSDR = 0.64. Conclusions We have identified a composite cognitive test score representing multiple cognitive domains that has improved power compared with the most sensitive single test item to track preclinical AD decline and evaluate preclinical AD treatments. We are confirming the power of the composite in independent cohorts and with other analytical approaches, which may result in refinements, have designated it as the primary endpoint in the Alzheimer’s Prevention Initiative’s preclinical treatment trials for individuals at high imminent risk for developing symptoms due to late-onset AD.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1016/j.jalz.2014.02.002

CHD1 and CHD2 are positive regulators of HIV-1 gene expression

NOMIS Researcher(s)

Published in

October 8, 2014

Background: Retroviruses encode a very limited number of proteins and therefore must exploit a wide variety of host proteins for completion of their lifecycle. Methods: We performed an insertional mutagenesis screen to identify novel cellular regulators of retroviral replication. Results: This approach identified the ATP-dependent chromatin remodeler, chromodomain helicase DNA-binding protein 2 (CHD2), as well as the highly related CHD1 protein, as positive regulators of both MLV and HIV-1 replication in rodent and human cells. RNAi knockdown of either CHD2 or the related CHD1 protein, in human cells resulted in a block to infection by HIV-1, specifically at the level of transcription. Conclusions: These results demonstrate that CHD1 and CHD2 can act as positive regulators of HIV-1 gene expression.

Research field(s)
Health Sciences, Biomedical Research, Virology

DOI
10.1186/1743-422X-11-180

Reprogramming by lineage specifiers: Blurring the lines between pluripotency and differentiation

NOMIS Researcher(s)

Published in

October 1, 2014

The generation of human induced pluripotent stem cells (iPS) has raised enormous expectations within the biomedical community due to their potential vast implications in regenerative and personalized medicine. However, reprogramming to iPS is still not fully comprehended. Difficulties found in ascribing specific molecular patterns to pluripotent cells (PSCs), and inherent inter-line and intra-line variability between different PSCs need to be resolved. Additionally, and despite multiple assumptions, it remains unclear whether the current in vitro culturing conditions for the maintenance and differentiation of PSCs do indeed recapitulate the developmental processes observed in vivo. As a consequence, basic questions such as what is the actual nature of PSCs remain unanswered and different theories have emerged in regards to the identity of these valuable cell population. Here we discuss on the published theories for defining PSC identity, the implications that the different postulated models have for the reprogramming field as well as speculate on potential future directions that might be opened once a precise knowledge on the nature of PSCs is accomplished.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1016/j.gde.2014.09.009

Developmental dyscalculia: a dysconnection syndrome?

NOMIS Researcher(s)

Published in

September 1, 2014

Numerical understanding is important for everyday life. For children with developmental dyscalculia (DD), numbers and magnitudes present profound problems which are thought to be based upon neuronal impairments of key regions for numerical understanding. The aim of the present study was to investigate possible differences in white matter fibre integrity between children with DD and controls using diffusion tensor imaging. White matter integrity and behavioural measures were evaluated in 15 children with developmental dyscalculia aged around 10 years and 15 matched controls. The main finding, obtained by a whole brain group comparison, revealed reduced fractional anisotropy in the superior longitudinal fasciculus in children with developmental dyscalculia. In addition, a region of interest analysis exhibited prominent deficits in fibres of the superior longitudinal fasciculus adjacent to the intraparietal sulcus, which is thought to be the core region for number processing. To conclude, our results outline deficient fibre projection between parietal, temporal and frontal regions in children with developmental dyscalculia, and therefore raise the question of whether dyscalculia can be seen as a dysconnection syndrome. Since the superior longitudinal fasciculus is involved in the integration and control of distributed brain processes, the present results highlight the importance of considering broader domain-general mechanisms in the diagnosis and therapy of dyscalculia.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1007/s00429-013-0597-4

Function of a foxp3 cis-element in protecting regulatory T cell identity

NOMIS Researcher(s)

Published in

August 14, 2014

The homeostasis of multicellular organisms requires terminally differentiated cells to preserve their lineage specificity. However, it is unclear whether mechanisms exist to actively protect cell identity in response to environmental cues that confer functional plasticity. Regulatory T (Treg) cells, specified by the transcription factor Foxp3, are indispensable for immune system homeostasis. Here, we report that conserved noncoding sequence 2 (CNS2), a CpG-rich Foxp3 intronic cis-element specifically demethylated in mature Tregs, helps maintain immune homeostasis and limit autoimmune disease development by protecting Treg identity in response to signals that shape mature Treg functions and drive their initial differentiation. In activated Tregs, CNS2 helps protect Foxp3 expression from destabilizing cytokine conditions by sensing TCR/NFAT activation, which facilitates the interaction between CNS2 and Foxp3 promoter. Thus, epigenetically marked cis-elements can protect cell identity by sensing key environmental cues central to both cell identity formation and functional plasticity without interfering with initial cell differentiation. © 2014 Elsevier Inc.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1016/j.cell.2014.07.030

Diversification of TAM receptor tyrosine kinase function

NOMIS Researcher(s)

Published in

January 1, 2014

The clearance of apoptotic cells is critical for both tissue homeostasis and the resolution of inflammation. We found that the TAM receptor tyrosine kinases Axl and Mer had distinct roles as phagocytic receptors in these two settings, in which they exhibited divergent expression, regulation and activity. Mer acted as a tolerogenic receptor in resting macrophages and during immunosuppression. In contrast, Axl was an inflammatory response receptor whose expression was induced by proinflammatory stimuli. Axl and Mer differed in their ligand specificities, ligand-receptor complex formation in tissues, and receptor shedding upon activation. These differences notwithstanding, phagocytosis by either protein was strictly dependent on receptor activation triggered by bridging of TAM receptor-ligand complexes to the ‘eat-me’ signal phosphatidylserine on the surface of apoptotic cells.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1038/ni.2986

Inflammasome-microbiota interplay in host physiologies

NOMIS Researcher(s)

Published in

November 13, 2013

Host defense responses against microbes are most often thought of in terms of effectors of microbial destruction. However, recent evidence demonstrates that the more complex interactions between the microbiota and innate immune mechanisms, such as the inflammasome-mediated response, cannot be readily explained within just the traditional paradigms of microbial killing mechanisms. In this review, the concepts of both resistance and tolerance are applied to inflammasome-microbiota interactions, and the various physiological consequences of this interplay, including roles in inflammation, tissue repair, tumorigenesis, and metabolism, are discussed. © 2013 Elsevier Inc.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1016/j.chom.2013.10.013

Reprogramming of human fibroblasts to pluripotency with lineage specifiers

NOMIS Researcher(s)

Published in

September 5, 2013

Since the initial discovery that OCT4, SOX2, KLF4, and c-MYC overexpression sufficed for the induction of pluripotency in somatic cells, methodologies replacing the original factors have enhanced our understanding of the reprogramming process. However, unlike in mouse, OCT4 has not been replaced successfully during reprogramming of human cells. Here we report on a strategy to accomplish this replacement. Through a combination of transcriptome and bioinformatic analysis we have identified factors previously characterized as being lineage specifiers that are able to replace OCT4 and SOX2 in the reprogramming of human fibroblasts. Our results show that it is possible to replace OCT4 and SOX2 simultaneously with alternative lineage specifiers in the reprogramming of human cells. At a broader level, they also support a model in which counteracting lineage specification networks underlies the induction of pluripotency. © 2013 Elsevier Inc.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1016/j.stem.2013.06.019

Adding an unnatural covalent bond to proteins through proximity-enhanced bioreactivity

NOMIS Researcher(s)

Published in

September 1, 2013

Natural proteins often rely on the disulfide bond to covalently link side chains. Here we genetically introduce a new type of covalent bond into proteins by enabling an unnatural amino acid to react with a proximal cysteine. We demonstrate the utility of this bond for enabling irreversible binding between an affibody and its protein substrate, capturing peptide-protein interactions in mammalian cells, and improving the photon output of fluorescent proteins. © 2013 Nature America, Inc. All rights reserved.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1038/nmeth.2595

Advances in cellular reprogramming: Moving toward a reprieve from immunogenicity

NOMIS Researcher(s)

Published in

September 1, 2013

Somatic cell nuclear reprogramming is opening new doors for the modeling of human disease phenotypes in vitro, the identification of novel therapeutic compounds and diagnostic factors as well as future autologous cell replacement therapies. Despite the potential that reprogramming technologies bring, there are remaining concerns preventing their broad application in the short-term. One of them is the safety concern associated with the use of stem cell derivatives, those generated by reprogramming or even when embryonic stem cells are employed. Here we summarize the current knowledge in the field of stem cells and reprogramming with a particular focus on the pitfalls preventing rapid translation of stem cell technologies into the clinic. We discuss the most recent findings on immunogenicity and tumorigenicity of reprogrammed cells. We additionally provide an overview on the potential applications that reprogramming approaches might bring to the immunological field and elaborate on the use of induced pluripotent stem cells (iPSCs) with pre-arranged immune receptors for the development of future immunotherapeutic approaches. The use of reprogramming approaches can represent and provide groundbreaking strategies previously unachievable for stem cell engineering aimed at modulating immune responses. In summary, we provide an overview on the different topics related to the use of stem cells and highlight the most provocative, yet perhaps currently underappreciated, aspect of combining immunological and reprogramming strategies for the treatment of human disease. © 2013 Elsevier B.V.

Research field(s)
Health Sciences, Clinical Medicine, Immunology

DOI
10.1016/j.imlet.2013.09.019

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