Academic literature on the topic 'Fused in Sarcoma'

Abstract Objectives Soft tissue sarcomas are a group of tumors derived from the mesenchymal origin. Historically, they have been classified according to morphologic and immunohistochemical characteristics. The advent of multiplexed next-generation sequencing (NGS), specifically RNA sequencing, has modified the classification of such tumors and others by determining categorization based on molecular alterations. The NUTM1 rearrangement, previously thought to be present only in carcinomas, has recently been reported in poorly differentiated high-grade sarcomas of the soft tissue. We present the first reported case of an epithelioid hyalinizing sarcoma harboring the MGA-NUTM1 fusion in an acral site. Methods Histopathologic, immunohistochemical, and molecular testing were performed on resection tissue. Results Histologically, the tumor showed an epithelioid morphology with prominent background hyalinization. Immunohistochemically, the tumor expressed CD99 and nuclear NUT-1. By NGS the tumor harbors MGA-NUTM1 fusion. Conclusions Our findings support more extensive use of NGS for accurate sarcoma classification and identification of potential therapeutic targets. Furthermore, they corroborate the fact that NUTM1-rearranged soft tissue tumors represent a spectrum of heterogeneous morphologic entities. This case also highlights the utility of NUT-1 immunohistochemical study as a possible screening tool for NUTM1-fused sarcomas.

Tropomyosin receptor kinase (TK) is encoded by the neurotrophic tyrosine receptor kinase genes (NTRK) 1, 2, and 3, whose activation plays an important role in cell cycle proliferation and survival. Fusions of one of these genes can lead to constitutive activation of TRK, which can potentially be oncogenic. NTRK fusions are commonly present in rare histologic tumor types. Among sarcomas, infantile fibrosarcoma shows NTRK fusion in more than 90% of the cases. Many other sarcoma types are also investigated for NTRK fusions. These fusions are druggable alteration of the agnostic type, meaning that all NTRK fused tumors can be treated with NTRK-inhibitors regardless of tumor type or tissue of origin. TRK-inhibitors have shown good response rates, with durable effects and limited side effects. Resistance to therapy will eventually occur in some cases, wherefore the next-generation TRK-inhibitors are introduced. The diagnosis of NTRK fused tumors, among them sarcomas, remains an issue, as many algorithms but no guidelines exist to date. Given the importance of this diagnosis, in this paper we aim to (1) analyze the histopathological features of sarcomas that correlate more often with NTRK fusions, (2) give an overview of the TRK-inhibitors and the problems that arise from resistance to the therapy, and (3) discuss the diagnostic algorithms of NTRK fused tumors with emphasis on sarcomas.

Fused in sarcoma (FUS) is a DNA/RNA binding protein that is involved in RNA metabolism and DNA repair. Numerous reports have demonstrated by pathological and genetic analysis that FUS is associated with a variety of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and polyglutamine diseases. Traditionally, the fibrillar aggregation of FUS was considered to be the cause of those diseases, especially via its prion-like domains (PrLDs), which are rich in glutamine and asparagine residues. Lately, a nonfibrillar self-assembling phenomenon, liquid–liquid phase separation (LLPS), was observed in FUS, and studies of its functions, mechanism, and mutual transformation with pathogenic amyloid have been emerging. This review summarizes recent studies on FUS self-assembling, including both aggregation and LLPS as well as their relationship with the pathology of ALS, FTLD, and other neurodegenerative diseases.

Cases of self-infection with cancer are described by Sippel. The author describes a case of self-infection with sarcoma. Dressmaker, 14 years old; complaints of severe constant pain in the lower abdomen. Recognized the neoplasm of common Fallopian tubes, or ovaries, probably of a sarcomatous nature. Gluttony showed that the tumor, extensively fused with the surrounding organs, belongs to the right appendage. When it was separated, part of its clumpy-purulent contents poured out into the abdominal cavity. The entire tumor was removed and, carefully examined, turned out to be a round-large-cell sarcoma, containing parts of fusiform cells in places.

Neurodegenerative disease patients suffer from cognitive decline and/or motor dysfunctions, depending on the different regions affected by the neuron loss. With aging being the major risk factor and a society with increased life expectancy, there is an urgent need to develop new effective treatments to alleviate the situation faced by patients, their families and society. Although neurodegenerative diseases including Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS) or frontotemporal dementia (FTD) lead to different clinical symptoms, they share common pathomechanisms, such as protein aggregation and altered RNA metabolism. A subset of ALS and FTD cases, for instance, is pathologically characterized by neuronal cytoplasmic inclusions containing aggregated Fused in Sarcoma (FUS) protein. There is also a genetic link, since FUS mutations cause ALS with FUS pathology. FUS is a DNA/RNA-binding protein known to regulate different steps of RNA metabolism, however, its exact function and target genes in neurons were unknown. In this study, I evaluated the neuronal role of FUS in alternative splicing using a candidate approach focusing on the microtubule-associated protein TAU. TAU is one of the most widely studied proteins in neurodegeneration research due to its aggregation in different tauopathies, most notably AD. Mutations in the TAU gene MAPT, that affect alternative splicing of exon 10, are known to cause another subtype of FTD. Here, I demonstrate that FUS depleted rat neurons, although having normal viability, show aberrant alternative splicing of TAU, with increased inclusion of exon 3 and exon 10, resulting in higher expression of the 2N and 4R TAU isoforms. Importantly, reintroduction of human FUS rescues aberrant splicing of TAU in FUS depleted neurons. Accordingly, overexpression of FUS decreases expression of 2N and 4R TAU isoforms. In mouse brain lysates, I detected direct FUS binding to TAU pre-mRNA, with strong binding around the regulated exon 10, often at AUU-rich RNA stretches. Since TAU splicing is regulated differently in humans and rodents, I also confirmed the role of human FUS in TAU exon 10 splicing using a TAU minigene and a human neuronal cell line. In addition, I analyzed the morphology and development of axons to evaluate the functional consequences of FUS depletion in neurons. Although FUS depleted neurons develop neurites normally, their axons are significantly shorter than in the control cells. Similar to observations in TAU/MAP1B knockout neurons, axons of FUS depleted neurons develop significantly larger growth cones with abnormal cytoskeletal organization. The development of growth cones in vivo is an essential step in axonal maintenance and repair. Altogether, this study identified TAU as the first physiological splice target of FUS in neurons. The newly discovered role of FUS in regulating the axonal cytoskeleton indicates that aberrant axonal function could contribute to the neuron loss seen in ALS/FTD cases with FUS aggregates.
Patienten mit neurodegenerativen Erkrankungen können an kognitivem Abbau und/oder motorische Störungen leiden, je nachdem welche Gehirnregion von dem Verlust von Neuronen betroffen ist. Da sich das Risiko einer neurodegenerativen Erkrankung mit zunehmendem Alter drastisch erhöht und wir eine Gesellschaft mit steigender Lebenserwartung haben, ist es dringend notwending, neue wirksame Behandlungsmethoden zu entwickeln, um die Situation, mit der sich Patienten, ihre Familien und die Gesellschaft konfrontiert sehen, zu erleichtern. Obwohl sich verschiedene neurodegenerative Erkrankungen wie die Alzheimer-Erkrankung (AD), Amyotrophe Lateralsklerose (ALS) oder Frontotemporale Demenz (FTD) klinisch unterscheiden, gibt es gemeinsame Pathomechanismen, wie Proteinaggregation und Störungen im RNA-Metabolismus. Bei einem Teil der ALS und FTD Patienten beobachtet man Ablagerungen aus aggregiertem Fused in Sarcoma (FUS) Protein. Des Weiteren verursachen FUS Mutationen ALS mit FUS neuronalen Aggregaten. FUS ist ein DNA/RNA-bindendes Protein, das verschiedene Schritte des RNA-Metabolismus reguliert. Die genaue Funktion von FUS und seine Zielgene in Neuronen waren jedoch bisher unbekannt. In dieser Studie habe ich die Funktion von FUS auf neuronales alternatives Spleißen mit einem Kandidaten-Ansatz untersucht, und mich insbesondere auf das Mikrotubuli-bindende Protein TAU fokussiert. Tau ist eines der bekanntesten Proteine in der Demenzforschung, da TAU Aggregate in verschiedenen sogenannten Tauopathien, insbesondere AD, gefunden wurden. Mutationen im TAU Gen MAPT, die das alternative Spleißen von TAU Exon 10 beeinflussen, können einen anderen Subtyp der FTD verursachen. Diese Studie zeigt, dass die Herunterregulierung (Gen-Knockdown) von FUS in murinen Neuronen das Überleben der Neuronen nicht beeinträchtigt, aber zu verändertem alternativen Spleißen von TAU mit einem erhöhten Einschluss von Exon 3 und Exon 10 führt und somit eine höhere Expression von den 2N und 4R TAU Isoformen verursacht. Eine wichtige Beobachtung dieser Studie war auch, dass die Expression von humanem FUS in FUS knockdown Neuronen aberrantes TAU Spleißen korrigieren kann. Dementsprechend führte auch die alleinige Überexpression von FUS zu einer verminderten Expression von 2N und 4R TAU. In Lysaten von Mausgehirnen konnte ich eine direkte Interaktion zwischen FUS und TAU RNA nachweisen, und zwar mit bevorzugter FUS Bindung nahe am regulierten TAU Exon 10 und oft an AUU-reichen RNA-Abschnitten. Da das Spleißen von TAU in Menschen und Nagetieren unterschiedlich reguliert wird, bestätigte ich mit sowohl einer menschlichen neuronalen Zelllinie als auch einem TAU-Minigen Konstrukt die Rolle von humanem FUS in TAU Exon 10 Spleißen. Um die funktionalen Konsequenzen von FUS knockdown in Neuronen zu bewerten, analysierte ich die Morphologie und Entwicklung der Axone. Obwohl Neuronen mit FUS knockdown normalen Neuriten bilden, sind ihre Axone deutlich kürzer als die der Kontroll-Neuronen. Wie auch schon in TAU/MAP1B knockout Neuronen beobachtet wurde, entwickeln FUS knockdown Neuronen Axone mit einem deutlich größeren Wachstumskegel und abnormer Zytoskelett-Organisation. Die dynamische Bildung axonaler Wachstumskegel ist ein wesentlicher Schritt in der axonalen Aufrechterhaltung und Reparatur in vivo. Insgesamt konnte diese Studie TAU als erstes physiologisches splice Zielgen von FUS in Neuronen identifizieren. Die neu entdeckte Funktion von FUS bei der Regulation des axonalen Zytoskelettes spricht für eine mögliche Rolle der veränderten axonalen Funktion beim Verlust von Neuronen in ALS/FTD Fällen mit FUS Aggregaten.

Amyotrophic lateral sclerosis (ALS) is an aggressive neurodegenerative disease characterised by the loss of upper and lower motor neurons, resulting in progressive paralysis, muscular atrophy and eventual death, on average, within 2-5 years post diagnosis. In ∼5% of patients with familial ALS (fALS), causative mutations occur within the gene encoding the RNA-binding protein, Fused in Sarcoma (FUS). Normally, FUS is predominantly localised to the nucleus and has several known roles in transcription, splicing and mRNA transport. Yet, in ALS patients with mutant forms of FUS, the protein becomes dramatically mislocalised to the cytoplasm and abnormal proteinaceous inclusions of FUS in the cytoplasm are observed post-mortem. Several questions remain: How do large pathological inclusions of FUS form? Is pathology induced via a gain or loss of protein function? Can aggregation in the cytoplasm of this normally nuclear protein be sufficient to produce toxicity? This thesis provides detailed characterisation of a novel pathway through which FUS may aggregate following its mislocalisation to the cytoplasm. This pathway is distinct from recruitment into stressinduced stress granules and can lead to the formation of large RNA-based FUS aggregates in a concentration-dependent manner. It was demonstrated that reduced protein-RNA interaction through transcriptional inhibition resulted in the dissolution and reassembly of these FUS aggregates into higher order RNA-free structures, reminiscent of inclusions seen in ALS-FUS patients. We also show in vivo that an initial insult of FUS aggregation in the cytoplasm is sufficient to elicit ALS-like pathology. In addition, how loss of FUS from the nucleus could affect the nuclear architecture was investigated, highlighting an important role for FUS in the maintenance of a protective subnuclear body, the paraspeckle, the disruption of which may contribute to the pathogenesis of FUSopathies. As such, this thesis identifies several novel mechanisms involved in the development and progression of FUSopathy, which may be useful for future therapeutic strategies targeting ALS caused by FUS mutation.

The fused in sarcoma (FUS) protein has been shown to be a significant disease protein in a subgroup of patients with frontotemporal lobar degeneration (FTLD). Nevertheless, the mechanism underlying FUS associated FTLD is only poorly understood. Recent research has identified a large hexanucleotide repeat expansion in chromosome 9 open reading frame 72 (C9orf72), reinforcing the association between C9orf72 and FTLD. Moreover, an unusual histopathological change has been observed within the granule cell layer of the cerebellum in chromosome 9p-linked frontotemporal dementia with motor neuron disease. Whether this type of cerebellar pathology is a pathological marker for chromosome 9p-linked families remains unknown. The purpose of this study was to genetically, neuropathologically and biochemically characterize FUS and C9orf72 in FTLD, and also to investigate the association between the cerebellar pathology and chromosome 9p-linked families. The genetic sequencing study searching for potential genetic factors of FUS in FTLD failed to detect any pathogenic mutations or variations. Immunohistochemical study for FUS pathology in FTLD provided strong evidence for FUS being the specific pathological protein in all forms of FTLD-FUS. Immunoblotting for FUS in FTLD detected one novel disease-associated FUS aggregate (~37 kDa) in the urea fraction of atypical FTLD with ubiquitinated inclusions (aFTLD-U) frontal cortical samples, suggesting this unique protein product might be more associated with disease than the full-length protein itself. Immunohistochemical study of C9orf72 in FTLD detected a 'synaptic' staining in CA sectors, as the most prominent histological feature identified. Immunoblotting for C9orf72 protein demonstrated no distinctive bands among different diagnostic groups, in frontal and cerebellar cortical regions. The present study also confirmed the presence of cerebellar p62 neuronal cytoplasmic inclusions (NCI) in a proportion of FTLD-TDP cases. Although most of these cases showed an autosomally dominant pattern of inheritance, not all of them shared a common C9orf72 haplotype, or mutation in C9orf72.Much work is still needed to investigate the underlying pathogenesis of FTLD-FUS. Attention should still be given to identifying possible genetic risk factors in FUS using a large series of FTLD samples and searching for other possible proteins within the FUS immunoreactive neuronal inclusions. Moreover, the target protein within the cerebellar p62 NCI remains unknown, but it is clear that it is not C9orf72 protein.

La present tesi té com a objectiu estudiar des de diferents punts de vista la degeneració lobular frontotemporal (FTLD), una malaltia neurodegenerativa que es caracteritza per la pèrdua neuronal focal en els lòbuls frontals i temporals. Aquesta malaltia és molt heterogènia des del punt de vista clínic, neuropatològic i genètic, com també en els mecanismes patogènics. Aquesta heterogeneïtat fa que sovint el diagnòstic no sigui fàcil i que la seva classificació nosològica i la recerca en els seus mecanismes sigui especialment complexa. En aquesta tesi s’aborda aquesta heterogeneïtat estudiant diferents aspectes de la FTLD. Primer, s’estudia la FTLD des de un punt de vista clínic: s’avaluen els nous criteris de la variant conductual d’aquesta malaltia (bvFTD) en la cohort de pacients seguits a la Unitat de Memòria de l'hospital de la Santa Creu i Sant Pau. Des del punt de vista genètic, es caracteritzen aspectes clínics i radiològics específics dels casos de FTLD que presenten una expansió de la repetició d’hexanucleòtids en el gen C9orf72. Seguidament, des del punt de vista dels biomarcadors, es mesura en sang i líquid cefaloraquidi la proteïna TDP-43 i la seva forma fosforilada (pTDP-43). En l’últim capítol, s’aprofundeix en els mecanismes moleculars de la patogènia de la FTLD amb dipòsits de proteïnes FUS i FET (FTLD-FET), s’estudien la metilació en les arginines presents en aquests proteïnes i com aquest canvi postraduccional regula el transport citoplasma-nucli de la proteïna FUS. Finalment, es realitza un estudi neuropatològic a on es comparen les diferències en el patró de metilació de la proteïna FUS entre la FTLD-FET i la esclerosi lateral amiotròfica amb mutacions en el gen de FUS (ALS-FUS). Aquest estudi afegeix una nova diferència entre la FTLD-FET i la ALS-FUS, tot i que ambdues comparteixen els dipòsits de la proteïna FUS.
The aim of the present thesis is to study frontotemporal lobar degeneration (FTLD), a neurodegenerative disease characterised by a focal neural loss in the frontal and the temporal lobes, from different perspectives. FTLD is a very heterogeneous disease either from the clinical or the neuropathological, genetic and pathogenic perspectives. This heterogeneity makes its diagnosis challenging and its nosologic classification and pathogenesis research especially puzzling. In the present thesis, this heterogeneity is addressed through studying FTLD from different angles. First, FTLD is investigated from a clinical viewpoint: the most recent clinical criteria about the behavioural variant of FTLD (bvFTD) are evaluated through the cohort of patients followed in the Memory Unit of Hospital de la Santa Creu i Sant Pau. From a genetic perspective, specific clinical and radiological features of the FTLD patients carrying a hexanucleotide repeat expansion in the C9orf72 gene are defined. Next, and from a biomarkers angle, TDP-43 protein and its phosphorylated form (pTDP-43) are measured in blood and in cerebrospinal fluid (CSF). In the last chapter, the molecular pathogenic mechanisms of FTLD with FUS- and FET-positive inclusions (FTLD-FET) are scrutinized, in order to study the methylation pattern of the arginines present in FUS protein and how this posttranslational modification regulates the cytoplasmic-nuclear transport. Finally, a neuropathological study is performed by means of the comparison of the differences in FUS methylation pattern between FTLD-FET and amyotrophic lateral sclerosis with FUS mutations (ALS-FUS). This study provides further evidence of the differences between FTLD-FET and ALS-FUS, despite the fact that both diseases share the deposition of the protein FUS.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron death and subsequent muscle atrophy. Approximately 15% of ALS cases are inheritable, and mutations in the Fused in Sarcoma (FUS) gene contribute to approximately 5% of these cases, as well as about 2% of sporadic cases. FUS performs a diverse set of cellular functions, including being a major regulator of RNA metabolism. FUS undergoes liquid- liquid phase transition in vitro, allowing for its participation in stress granules and RNA transport granules. Phase transition also contributes to the formation of cytoplasmic inclusions found in the cell bodies of FUS ALS patients motor neurons. The nature of these inclusions has remained elusive, as the proteins localized to them have not been identified. Additionally, the functional consequence of the accumulation of cytoplasmic FUS inclusions has not been established, nor is it understood how they contribute to selective motor neuron death. We carried out two related, but independent studies to characterize the proteins that may be included in FUS-positive inclusions. In this first study, we utilized immunoprecipitation of wild-type and mutant FUS in the presence and absence of RNase, followed by LC MS/MS. The identified proteins represent those that directly or indirectly interact with FUS, with relatively high affinity that can be pulled down with immunoprecipitation. A wide variety of interacting proteins were identified and they are involved in a multitude of pathways including: chromosomal organization, transcription, RNA splicing, RNA transport, localized translation, and stress response. Their interaction with FUS varied greatly in their requirements for RNA. Most notably, FUS interacted with hnRNPA1 and Matrin-3, proteins also known to cause familial ALS. Immunofluorescent staining of proteins interacting with mutant FUS were localized to cytoplasmic inclusions. We concluded that mis-localization of these proteins potentially lead to their dysregulation or loss of function, thus contributing to FUS pathogenesis. In the second study, we developed a protocol to isolate dynamic FUS inclusions and employed LC MS/MS to identify all proteins associated with FUS inclusions. We identified a cohort of proteins involved in translation, splicing, and RNA export to be associated with the FUS inclusions. Further pathway and disease association analysis suggested that proteins associated with translation and RNA quality control pathways may be the most significant. Protein translation assays using both N2A and ALS patient fibroblasts demonstrated suppression of protein biosynthesis in mutant FUS expressing cells. However, translation initiation was not impaired. To understand how protein synthesis is suppressed by mutant FUS mediated defects in RNA metabolism, we examined changes in a well conserved RNA turnover pathway namely: nonsense mediated decay (NMD). We found that NMD is hyperactivated in cells expressing mutant FUS, likely due to chronic suppression of protein translation shifting the pathways autoregulatory circuit to allow for hyperactivation. We concluded that mutant FUS suppresses protein biosynthesis and disrupts NMD regulation. These defects together likely contribute to motor neuron death.

Neurodegenerative diseases (NDs) are characterized by specific dysfunction and damage of neurons related to pathologically changed proteins that deposit in the patient brain but also in peripheral organs. These proteins can be used for therapy or used as biomarkers. Except for a plethora of alterations revealed for dissimilar neurodegeneration-related proteins, amyloid-β, prion protein, TAR DNA-binding protein 43 (TDP-43, transactive response DNA binding protein 43 kDa), tau and α-synuclein, or fused in sarcoma protein (FUS), molecular classification of NDs depend on the full morphological assessment of protein deposits, their spreading in the brain, and their correspondence to clinical signs with specific genetic modifications. The current chapter represents the etiology of neurodegeneration, classification of NDs, concentrating on the maximum applicable biochemical and anatomical characteristics and most imperative NDs.

Fronto-temporal dementia (FTD) is a heterogenous clinical syndrome with a progressive decline in behaviour, executive function, and language. Approximately 40% of FTD patients report a family history, and 10–15% of FTD cases show an autosomal dominant pattern of inheritance. FTD often mimics psychiatric disorders because of the prominent behavioural features, and particularly in the early stages, the only manifestation of illness may be purely behavioural. There is significant clinical, pathological, and genetic overlap between FTD and motor neuron disease/amyotrophic lateral sclerosis (FTD-ALS) and two atypical Parkinsonian syndromes—progressive supranuclear palsy (PSP) and cortico-basal degeneration (CBD). FTD is associated with non-Alzheimer’s disease pathology and the molecular aggregation of specific proteins—tau, TAR-DNA binding protein (TDP), and fused in sarcoma (FUS). Advances in clinical, imaging, and molecular characterization have increased the accuracy of FTD diagnosis. At present, appropriate management of FTD symptoms involves a combination of pharmacological therapy with techniques involving behavioural, physical, and environmental manipulation.