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NOMIS Insights

Research is the vital expression of humankind’s most important qualities: curiosity and imagination.

Explorers, inventors, pioneers—dedicated researchers on the frontiers of science and the humanities.

Insight, when it comes, changes everything.

Publications

The NOMIS community of researchers and partners is instrumental in driving interdisciplinary collaboration, generating insights and ultimately advancing our understanding of the world. A key component of these efforts is knowledge sharing. Comprising a unique offering of engaging scientific lectures, insightful films about our awardees’ research, and a comprehensive publication database, NOMIS Insights are designed to facilitate the sharing of knowledge. They showcase the groundbreaking findings and innovative perspectives born from NOMIS-supported research endeavors, embodying our dedication to enabling scientific progress.

Our NOMIS Insight database provides a comprehensive source of all publications resulting from NOMIS-supported research projects.

Intraneuronal protein aggregation as a trigger for inflammation and neurodegeneration in the aging brain

NOMIS Researcher(s)

Published in

January 1, 2017

Age is, by far, the greatest risk factor for Alzheimer’s disease (AD) , yet few A Ddrug candidateshave been generated that target pathways specifically associated with the aging process itself. Two ubiquitous features of the aging brain are the intracellular accumulation of aggregated proteins and inflammation. As intraneuronal amyloid protein is detected before markers of inflammation, we argue that old, age-associated, aggregated proteins in neurons can induce inflammation, resulting inmultiple forms of brain toxicities. The consequence is the increased risk of old, age-associated, neurodegenerative diseases. As most of these diseases are associated with the accumulation of aggregated proteins, it is possible that any therapeutic that reduces intracellular protein aggregation will benefit all. – Currais, A., Fischer, W., Maher, P., Schubert, D. Intraneuronal protein aggregation as a trigger for inflammation and neurodegeneration in the aging brain.

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

DOI
10.1096/fj.201601184

Mentalizing homeostasis: The social origins of interoceptive inference

NOMIS Researcher(s)

Published in

January 1, 2017

Is the self already relational in its very bodily foundations? The question of whether our mental life is initially and primarily shaped by embodied dimensions of the individual or by interpersonal relations is debated in many fields, including psychology, philosophy, psychoanalysis, and more recently, cognitive neuroscience. In this interdisciplinary target article, we put forward the radical claim that even some of the most minimal aspects of selfhood, namely the feeling qualities associated with being an embodied subject, are fundamentally shaped by embodied interactions with other people in early infancy and beyond. Such embodied interactions allow the developing organism to mentalize its homeostatic regulation. In other words, embodied interactions contribute directly to the building of mental models of the infant’s physiological states, given the need to maintain such states within a given dynamic range despite internal or external perturbations. Specifically, our position rests on the following three propositions: (1) the progressive integration and organization of sensory and motor signals constitutes the foundations of the minimal self, a process which we have linked to contemporary, computational models of brain function and named “embodied mentalization”; (2) interactions with other people are motivated and constrained by the same principles that govern the “mentalization” of sensorimotor signals in the individual-and hence the mentalization of one’s body can include signals from other bodies in physical proximity and interaction, especially in interaction with particular bodies. (3) Crucially, given the dependency of humans in early infancy, there is a “homeostatically necessary” plethora of such embodied “proximal” interactions, especially as regards interoception. Collectively, such experiences of proximal intercorporeality “sculpt” the mentalization process and hence the constitution of the minimal self, including the progressive sophistication of mental distinctions between “subject-object,” “self-other” and even “pleasure-pain.” Finally, we explore notions of cardiac and more broadly interoceptive awareness as later, cognitive acquisitions that allow us to progressively solidify such distinctions, as well as understand and empathise with other people.

Research field(s)
Health Sciences, Psychology & Cognitive Sciences, Experimental Psychology

DOI
10.1080/15294145.2017.1294031

Surgical correction of septal deviation after Le Fort I osteotomy

NOMIS Researcher(s)

Published in

December 1, 2016

Background: The Le Fort I osteotomy is one of the most widely used and useful procedure to correct the dentofacial deformities of the midface. The changes of the maxilla position affect to overlying soft tissue including the nasal structure. Postoperative nasal septum deviation is a rare and unpredicted outcome after the surgery. There are only a few reports reporting the management of this complication. Case Presentation: In our department, three cases of the postoperative nasal septum deviation after the Le Fort I osteotomy had been experienced. Via limited intraoral circumvestibular incision, anterior maxilla, the nasal floor, and the anterior aspect of the septum were exposed. The cartilaginous part of the nasal septum was resected and repositioned to the midline and the anterior nasal spine was recontoured. Alar cinch suture performed again to prevent the sides of nostrils from flaring outwards. After the procedure, nasal septum deviation was corrected and the esthetic outcomes were favorable. Conclusion: Careful extubation, intraoperative management of nasal septum, and meticulous examination of pre-existing nasal septum deviation is important to avoid postoperative nasal septum deviation. If it existed after the maxillary osteotomy, septum repositioning technique of the current report can successfully correct the postoperative septal deviation.

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

DOI
10.1186/s40902-016-0067-z

In vivo genome editing via CRISPR/Cas9 mediated homology-independent targeted integration

NOMIS Researcher(s)

Published in

December 1, 2016

Targeted genome editing via engineered nucleases is an exciting area of biomedical research and holds potential for clinical applications. Despite rapid advances in the field, in vivo targeted transgene integration is still infeasible because current tools are inefficient, especially for non-dividing cells, which compose most adult tissues. This poses a barrier for uncovering fundamental biological principles and developing treatments for a broad range of genetic disorders. Based on clustered regularly interspaced short palindromic repeat/Cas9 (CRISPR/Cas9) technology, here we devise a homology-independent targeted integration (HITI) strategy, which allows for robust DNA knock-in in both dividing and non-dividing cells in vitro and, more importantly, in vivo (for example, in neurons of postnatal mammals). As a proof of concept of its therapeutic potential, we demonstrate the efficacy of HITI in improving visual function using a rat model of the retinal degeneration condition retinitis pigmentosa. The HITI method presented here establishes new avenues for basic research and targeted gene therapies.

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

DOI
10.1038/nature20565

Disease Tolerance Trick or Treat: Give Your Brain Something Good to Eat

NOMIS Researcher(s)

Published in

September 8, 2016

The reprioritization of feeding motivations during disease is proposed to optimize host defense strategies against infection. Now, Wang et al. identify that sickness-induced anorexia differentially shapes the metabolic requirements of cellular stress adaptations, leading to opposite impact on disease tolerance upon bacterial versus viral infections.

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

DOI
10.1016/j.cell.2016.08.034

Reduced hnRNPA3 increases C9orf72 repeat RNA levels and dipeptide-repeat protein deposition

NOMIS Researcher(s)

Published in

September 1, 2016

Intronic hexanucleotide (G4C2) repeat expansions in C9orf72 are genetically associated with frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). The repeat RNA accumulates within RNA foci but is also translated into disease characterizing dipeptide repeat proteins (DPR). Repeat-dependent toxicity may affect nuclear import. hnRNPA3 is a heterogeneous nuclear ribonucleoprotein, which specifically binds to the G4C2 repeat RNA. We now report that a reduction of nuclear hnRNPA3 leads to an increase of the repeat RNA as well as DPR production and deposition in primary neurons and a novel tissue culture model that reproduces features of the C9orf72 pathology. In fibroblasts derived from patients carrying extended C9orf72 repeats, nuclear RNA foci accumulated upon reduction of hnRNPA3. Neurons in the hippocampus of C9orf72 patients are frequently devoid of hnRNPA3. Reduced nuclear hnRNPA3 in the hippocampus of patients with extended C9orf72 repeats correlates with increased DPR deposition. Thus, reduced hnRNPA3 expression in C9orf72 cases leads to increased levels of the repeat RNA as well as enhanced production and deposition of DPR proteins and RNA foci.

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

DOI
10.15252/embr.201541724

Minor intron splicing is regulated by FUS and affected by ALS-associated FUS mutants

NOMIS Researcher(s)

Published in

July 15, 2016

Fused in sarcoma (FUS) is a ubiquitously expressed RNA-binding protein proposed to function in various RNA metabolic pathways, including transcription regulation, pre-mRNA splicing, RNA transport and microRNA processing. Mutations in the FUS gene were identified in patients with amyotrophic lateral sclerosis (ALS), but the pathomechanisms by which these mutations cause ALS are not known. Here, we show that FUS interacts with the minor spliceosome constituent U11 snRNP, binds preferentially to minor introns and directly regulates their removal. Furthermore, a FUS knockout in neuroblastoma cells strongly disturbs the splicing of minor intron-containing mRNAs, among them mRNAs required for action potential transmission and for functional spinal motor units. Moreover, an ALS-associated FUS mutant that forms cytoplasmic aggregates inhibits splicing of minor introns by trapping U11 and U12 snRNAs in these aggregates. Collectively, our findings suggest a possible pathomechanism for ALS in which mutated FUS inhibits correct splicing of minor introns in mRNAs encoding proteins required for motor neuron survival.

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

DOI
10.15252/embj.201593791

Cooperative microbial tolerance behaviors in host-microbiota mutualism

NOMIS Researcher(s)

Published in

June 2, 2016

Animal defense strategies against microbes are most often thought of as a function of the immune system, the primary function of which is to sense and kill microbes through the execution of resistance mechanisms. However, this antagonistic view creates complications for our understanding of beneficial host-microbe interactions. Pathogenic microbes are described as employing a few common behaviors that promote their fitness at the expense of host health and fitness. Here, a complementary framework is proposed to suggest that, in addition to pathogens, beneficial microbes have evolved behaviors to manipulate host processes in order to promote their own fitness and do so through the promotion of host health and fitness. In this Perspective, I explore the idea that patterns or behaviors traditionally ascribed to pathogenic microbes are also employed by beneficial microbes to promote host tolerance defense strategies. Such strategies would promote host health without having a negative impact on microbial fitness and would thereby yield cooperative evolutionary dynamics that are likely required to drive mutualistic co-evolution of hosts and microbes.

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

DOI
10.1016/j.cell.2016.05.049

Understanding the molecular mechanisms of reprogramming

NOMIS Researcher(s)

Published in

May 6, 2016

Despite the profound and rapid advancements in reprogramming technologies since the generation of the first induced pluripotent stem cells (iPSCs) in 2006[1], the molecular basics of the process and its implications are still not fully understood. Recent work has suggested that a subset of TFs, so called “Pioneer TFs”, play an important role during the stochastic phase of iPSC reprogramming [2-6]. Pioneer TFs activities differ from conventional transcription factors in their mechanism of action. They bind directly to condensed chromatin and elicit a series of chromatin remodeling events that lead to opening of the chromatin. Chromatin decondensation by pioneer factors progressively occurs during cell division and in turn exposes specific gene promoters in the DNA to which TFs can now directly bind to promoters that are readily accessible[2, 6]. Here, we will summarize recent advancements on our understanding of the molecular mechanisms underlying reprogramming to iPSC as well as the implications that pioneer Transcription Factor activities might play during different lineage conversion processes.

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

DOI
10.1016/j.bbrc.2015.11.120

TAM receptors regulate multiple features of microglial physiology

NOMIS Researcher(s)

Published in

April 14, 2016

Microglia are damage sensors for the central nervous system (CNS), and the phagocytes responsible for routine non-inflammatory clearance of dead brain cells. Here we show that the TAM receptor tyrosine kinases Mer and Axl regulate these microglial functions. We find that adult mice deficient in microglial Mer and Axl exhibit a marked accumulation of apoptotic cells specifically in neurogenic regions of the CNS, and that microglial phagocytosis of the apoptotic cells generated during adult neurogenesis is normally driven by both TAM receptor ligands Gas6 and protein S. Using live two-photon imaging, we demonstrate that the microglial response to brain damage is also TAM-regulated, as TAM-deficient microglia display reduced process motility and delayed convergence to sites of injury. Finally, we show that microglial expression of Axl is prominently upregulated in the inflammatory environment that develops in a mouse model of Parkinson’s disease. Together, these results establish TAM receptors as both controllers of microglial physiology and potential targets for therapeutic intervention in CNS disease.

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

DOI
10.1038/nature17630

Monomethylated and unmethylated FUS exhibit increased binding to Transportin and distinguish FTLD-FUS from ALS-FUS

NOMIS Researcher(s)

Published in

April 1, 2016

Deposition of the nuclear DNA/RNA-binding protein Fused in sarcoma (FUS) in cytosolic inclusions is a common hallmark of some cases of frontotemporal lobar degeneration (FTLD-FUS) and amyotrophic lateral sclerosis (ALS-FUS). Whether both diseases also share common pathological mechanisms is currently unclear. Based on our previous finding that FUS deposits are hypomethylated in FTLD-FUS but not in ALS-FUS, we have now investigated whether genetic or pharmacological inactivation of Protein arginine methyltransferase 1 (PRMT1) activity results in unmethylated FUS or in alternatively methylated forms of FUS. To do so, we generated FUS-specific monoclonal antibodies that specifically recognize unmethylated arginine (UMA), monomethylated arginine (MMA) or asymmetrically dimethylated arginine (ADMA). Loss of PRMT1 indeed not only results in an increase of UMA FUS and a decrease of ADMA FUS, but also in a significant increase of MMA FUS. Compared to ADMA FUS, UMA and MMA FUS exhibit much higher binding affinities to Transportin-1, the nuclear import receptor of FUS, as measured by pull-down assays and isothermal titration calorimetry. Moreover, we show that MMA FUS occurs exclusively in FTLD-FUS, but not in ALS-FUS. Our findings therefore provide additional evidence that FTLD-FUS and ALS-FUS are caused by distinct disease mechanisms although both share FUS deposits as a common denominator.

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

DOI
10.1007/s00401-016-1544-2

Establishment of human iPSC-based models for the study and targeting of glioma initiating cells

NOMIS Researcher(s)

Published in

February 22, 2016

Glioma tumour-initiating cells (GTICs) can originate upon the transformation of neural progenitor cells (NPCs). Studies on GTICs have focused on primary tumours from which GTICs could be isolated and the use of human embryonic material. Recently, the somatic genomic landscape of human gliomas has been reported. RTK (receptor tyrosine kinase) and p53 signalling were found dysregulated in â1/490% and 86% of all primary tumours analysed, respectively. Here we report on the use of human-induced pluripotent stem cells (hiPSCs) for modelling gliomagenesis. Dysregulation of RTK and p53 signalling in hiPSC-derived NPCs (iNPCs) recapitulates GTIC properties in vitro. In vivo transplantation of transformed iNPCs leads to highly aggressive tumours containing undifferentiated stem cells and their differentiated derivatives. Metabolic modulation compromises GTIC viability. Last, screening of 101 anti-cancer compounds identifies three molecules specifically targeting transformed iNPCs and primary GTICs. Together, our results highlight the potential of hiPSCs for studying human tumourigenesis.

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

DOI
10.1038/ncomms10743

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

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

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

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

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

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