33 research outputs found
Aberrant Expression of and Cell Death Induction by Engagement of the MHC-II Chaperone CD74 in Anaplastic Large Cell Lymphoma (ALCL)
SIMPLE SUMMARY: Anaplastic large cell lymphoma (ALCL) is a lymphoid malignancy considered to be derived from T cells. Currently, two types of systemic ALCL are distinguished: anaplastic lymphoma kinase (ALK)-positive and ALK-negative ALCL. Although ALK(+) and ALK(â) ALCL differ at the genomic and molecular levels, various key biological and molecular features are highly similar between both entities. We have developed the concept that both ALCL entities share a common principle of pathogenesis. In support of this concept, we here describe a common deregulation of CD74, which is usually not expressed in T cells, in ALCL. Ligation of CD74 induces cell death of ALCL cells in various conditions, and an anti-CD74-directed antibody-drug conjugate efficiently kills ALCL cell lines. Furthermore, we reveal expression of the proto-oncogene and known CD74 interaction partner MET in a fraction of ALCL cases. These data give insights into ALCL pathogenesis and might help to develop new treatment strategies for ALCL. ABSTRACT: In 50â60% of cases, systemic anaplastic large cell lymphoma (ALCL) is characterized by the t(2;5)(p23;q35) or one of its variants, considered to be causative for anaplastic lymphoma kinase (ALK)-positive (ALK(+)) ALCL. Key pathogenic events in ALK-negative (ALK(â)) ALCL are less well defined. We have previously shown that deregulation of oncogenic genes surrounding the chromosomal breakpoints on 2p and 5q is a unifying feature of both ALK(+) and ALK(â) ALCL and predisposes for occurrence of t(2;5). Here, we report that the invariant chain of the MHC-II complex CD74 or li, which is encoded on 5q32, can act as signaling molecule, and whose expression in lymphoid cells is usually restricted to B cells, is aberrantly expressed in T cell-derived ALCL. Accordingly, ALCL shows an altered DNA methylation pattern of the CD74 locus compared to benign T cells. Functionally, CD74 ligation induces cell death of ALCL cells. Furthermore, CD74 engagement enhances the cytotoxic effects of conventional chemotherapeutics in ALCL cell lines, as well as the action of the ALK-inhibitor crizotinib in ALK(+) ALCL or of CD95 death-receptor signaling in ALK(â) ALCL. Additionally, a subset of ALCL cases expresses the proto-oncogene MET, which can form signaling complexes together with CD74. Finally, we demonstrate that the CD74-targeting antibody-drug conjugate STRO-001 efficiently and specifically kills CD74-positive ALCL cell lines in vitro. Taken together, these findings enabled us to demonstrate aberrant CD74-expression in ALCL cells, which might serve as tool for the development of new treatment strategies for this lymphoma entity
Genomic loss of the putative tumor suppressor gene E2A in human lymphoma
The transcription factor E2A is essential for lymphocyte development. In this study, we describe a recurrent E2A gene deletion in at least 70% of patients with SĂ©zary syndrome (SS), a subtype of T cell lymphoma. Loss of E2A results in enhanced proliferation and cell cycle progression via derepression of the protooncogene MYC and the cell cycle regulator CDK6. Furthermore, by examining the gene expression profile of SS cells after restoration of E2A expression, we identify several E2A-regulated genes that interfere with oncogenic signaling pathways, including the Ras pathway. Several of these genes are down-regulated or lost in primary SS tumor cells. These data demonstrate a tumor suppressor function of E2A in human lymphoid cells and could help to develop new treatment strategies for human lymphomas with altered E2A activity
Building connectomes using diffusion MRI: why, how and but
Why has diffusion MRI become a principal modality for mapping connectomes in vivo? How do different image acquisition parameters, fiber tracking algorithms and other methodological choices affect connectome estimation? What are the main factors that dictate the success and failure of connectome reconstruction? These are some of the key questions that we aim to address in this review. We provide an overview of the key methods that can be used to estimate the nodes and edges of macroscale connectomes, and we discuss open problems and inherent limitations. We argue that diffusion MRI-based connectome mapping methods are still in their infancy and caution against blind application of deep white matter tractography due to the challenges inherent to connectome reconstruction. We review a number of studies that provide evidence of useful microstructural and network properties that can be extracted in various independent and biologically-relevant contexts. Finally, we highlight some of the key deficiencies of current macroscale connectome mapping methodologies and motivate future developments
A roadmap of constitutive NF-ÎșB activity in Hodgkin lymphoma: Dominant roles of p50 and p52 revealed by genome-wide analyses
The analysis of IL-4 expression heterogeneity in differentiated Th2 cells
GesamtdissertationInterleukin-4 spielt als zentrales Zytokin der Th2-vermittelten Immunantwort
sowohl eine bedeutende Rolle bei der Entwicklung und Differenzierung von
Th2-Effektorzellen als auch bei der Vermittlung wichtiger
Th2-Effektorfunktionen. Eine Dysregulation der IL-4-Expression steht dabei in
pathogenetischem Zusammenhang mit der Entstehung allergischer Erkrankungen wie
Asthma bronchiale und anaphylaktischen Reaktionen. Vor diesem Hintergrund war
es das Ziel dieser Arbeit, die stochastische Regulation der IL-4-Expression in
differenzierten Th2-Zellen, insbesondere den Status der
Transkriptionsfaktorbesetzung am IL-4-Lokus in IL-4-produzierenden und
IL-4-nichtproduzierenden Th2-Zellen, zu analysieren, um damit ein
tiefergehenderes VerstÀndnis der komplexen IL-4-Regulation auf molekularer
Ebene zu erhalten. FĂŒr die Untersuchungen wurde dafĂŒr ein etabliertes Th2-in-
vitro-Modellsystem verwendet, dass die Analyse der IL-4-Expressionsregulation
in differenzierten Th2-Zellen erlaubt. Mittels der magnetischen Chromatin-
ImmunoprÀzipitation konnte dabei zunÀchst gezeigt werden, dass nach
Aktivierung differenzierter Th2-Zellen ein Transkriptionsfaktorkomplex,
bestehend aus den Faktoren NFAT1, NFAT2, NF-ÎșB/p65, c-MAF, p300, SWI/SNF/Brg1
und GATA-3, transient an den IL-4-Promoter/CIRE-Region und an die HS Va bindet
und ĂŒber die Rekrutierung der RNA-Polymerase-II die IL-4-Transkription
induziert. Der Transkriptionsfaktor STAT6 ist hingegen sowohl in ruhenden als
auch aktivierten Th2-Zellen konstitutiv mit dem IL-4-Lokus assoziiert. Durch
Verwendung des NFAT-spezifischen Inhibitors BTP1 konnte weitergehend
demonstriert werden, dass die Rekrutierung des gesamten
Transkriptionsfaktorkomplexes an den IL-4-Promoter von der Aktivierung des
Transkriptionsfaktors NFAT abhÀngig ist. In der Analyse der
Transkriptionsfaktorbesetzung in IL-4-produzierenden und
IL-4-nichtproduzierenden Th2-Zellen zeigte sich, dass beide Zellpopulationen
durch eine Àquivalente Expression, Aktivierung und DNA-BindungsaktivitÀt der
NFAT-Faktoren NFAT1 und NFAT2 charakterisiert sind, NFAT1/2 sowie der NFAT-
vermittelte Transkriptionsfaktorkomplex jedoch selektiv nur am IL-4-Promoter
der IL-4-produzierenden Th2-Zellen gebunden ist. An der HS Va konnte ebenso
eine differentielle BindungsaktivitÀt des Transkriptionsfaktorkomplexes
nachgewiesen werden, wobei jedoch auch IL-4-Nichtproduzenten durch eine im
Vergleich zu ruhenden Th2-Zellen geringfĂŒgige Transkriptionsfaktorbesetzung
gekennzeichnet sind. FĂŒr die Transkriptionsfaktoren STAT6 und GATA-3 zeigte
sich im Gegensatz dazu eine Àquivalente BindungsaktivitÀt an der IL-4-Promoter
-/CIRE-Region bzw. der HS Va. Durch eine genomweite Genexpressionsanalyse
konnten verschiedene, zwischen IL-4-produzierenden und
IL-4-nichtproduzierenden Th2-Zellen differentiell exprimierte Gene detektiert
werden, die einen Ausgangspunkt fĂŒr weitergehende Untersuchungen zu den
zellbiologischen Mechansismen der stochastischen IL-4-Regulation darstellen.
Aus den gewonnenen Erkenntnissen der Transkriptionsfaktorbindungsanalysen
wurde zussammenfassend ein molekulares Modell der stochastisch-determinierten
IL-4-Expression entworfen. Dieses postuliert die PrÀsenz eines
transkriptionellen Repressors, der spezifisch an den IL-4-Promoter bindet und
ĂŒber die Kompetition mit NFAT um die Bindung an den IL-4-Promoter die
stochastische Regulation der IL-4-Expression vermittelt. DiesbezĂŒglich konnte
im Rahmen der differentiellen Genexpressionsanalyse der selektiv in den
IL-4-nichtproduzierenden Th2-Zellen erhöht exprimierte Faktor Interferon
regulatory factor 1 (IRF1) detektiert werden, fĂŒr den bereits eine Bindung am
IL-4-Promoter sowie eine inhibitorische AktivitÀt im Zusammenhang mit der
IL-4-Transkription beschrieben wurde. Der transkriptionelle Repressor IRF1
stellt somit einen möglichen Vermittler der stochastischen Regulation der
IL-4-Expression dar und muss diesbezĂŒglich in weiteren Untersuchungen nĂ€her
analysiert werden.Interleukin-4 is a central cytokine of the Th2-mediated immune response and is
critical for the differentiation of Th2 cells and various Th2 effector
functions. A dysregulation of IL-4 expression is often associated with
overhelming allergic reactions such as asthma bronchiale or anaphylactic
immune reactions. On the cellular level of fully differentiated Th2 effector
cells, IL-4 expression is regulated in a stochastic manner. Within a Th2 cell
population, only a part of the cells express IL-4 upon T cell receptor
stimulation. To get inside into the underlying mechanisms of the phenomenon of
IL-4 expression heterogeneity in differentiated Th2 cells we analyzed the
transcription factor recruitment to the IL-4-promoter and the hypersensitivity
site Va in separated IL-4-producing and IL-4-nonproducing, murine Th2 cells.
By using the magnetic chromatin immunoprecipitation method we could show that
a protein complex consisting of NFAT1, NFAT2, NF-ÎșB, c-MAF, p300/CBP,
SWI/SNF/Brg1, GATA-3 and STAT6 is associated with the IL-4 gene locus and
drives the rapid and stimulation-dependent IL-4 transcription . Compared to
IL-4-producing Th2 cells, IL-4-nonproducing Th2 cells are characterized by the
inability of NFAT1/2 and the other components of the transcriptional complex
c-MAF, NF-ÎșB, p300/CBP and SWI/SNF to get associated with the IL-4 gene locus
upon restimulation. However, the differential DNA binding activity of the
characterized protein complex in IL-4-producing and IL-4-nonproducing Th2
cells is restricted to the IL-4 gene locus. By performing whole genome mRNA
expression analysis we could further detect a number of genes differentially
expressed in IL-4-producing and IL-4-nonproducing Th2 cells. Based on the
differential binding activity of the analysed transcription factor complex and
various genes differentially expressed in both Th2 subpopulations we postulate
a molecular model for IL-4 expression heterogeneity in differentiated Th2
cells
Black Atlantic Hybrids: Samples of Brazilian Music of the 1960s and 1970s in U.S. American Hip Hop
Kreher S. Black Atlantic Hybrids: Samples of Brazilian Music of the 1960s and 1970s in U.S. American Hip Hop. Masterarbeiten InterAmerikanische Studien. Vol 3. Bielefeld: kipu-Verl.; 2022.This monograph examines how sampling in U.S. Hip Hop
transgresses national and regional boundaries. By contextualizing
and comparing the Brazilian source material from the 1960s and
1970s with U.S. Hip Hop from the 1990s onwards, it traces flows of
musicians, music, and ideology along the Interamerican U.S.-Brazil
axis. The fusion and recontextualization of music styles through
sampling shed light on aspects of the African American struggle
and result in transcultural musical hybrids that encompass the
African diaspora in the Americas, activism, cultural resistance, and
âdouble consciousnessâ. Building on postmodern intertextuality,
these hybrids become products of a âsonic cosmopolitanismâ for a
world shaped by the heritage of the black Atlantic
Signaling pathways and cytokine expression in human lymphoma
Der Schwerpunkt dieser Arbeit ist die Charakterisierung aktivierter Signalwege
sowie die Ursachen und Konsequenzen einer deregulierten Zytokinexpression bei
malignen Lymphomen. Dabei wurden vorrangig das klassische Hodgkin-Lymphom
(cHL), periphere T-Zell-Lymphome sowie aggressive Lymphome des ZNS (ZNSL)
analysiert. Im cHL konnte der Transkriptionsfaktor IRF5 als zentraler
Regulator des inflammatorischen PhÀnotyps der Hodgkin-/Reed-Sternberg
(HRS)-Zellen sowie als entscheidender Faktor fĂŒr die deregulierte
Zytokinexpression identifiziert werden. Weiterhin konnte gezeigt werden, dass
die Expression des myeloischen Proto-Onkogens CSF1R in HRS-Zellen durch eine
epigenetische Derepression eines long-terminal-repeat-Elementes induziert wird
und wichtige Ăberlebenssignale in HRS-Zellen vermittelt. FĂŒr die aberrante
Expression des Zytokins IL-21 konnte herausgearbeitet werden, dass dieses zur
Aktivierung von STAT3 und nachgeschalteter STAT3-Zielgene fĂŒhrt und Hodgkin-
Zellen vor CD95-induzierter Apoptose schĂŒtzt. Zudem ist IL-21 ĂŒber die
Induktion des Chemokins MIP-3 an der Ausbildung des immunsuppressiven
zellulÀren Begleitinfiltrates durch Rekrutierung regulatorischer T-Zellen
beteiligt. Im Rahmen weiterer Arbeiten konnten verschiedene
Signalwegsalterationen und genetische Aberrationen in zwei unterschiedlichen
EntitĂ€ten reifzelliger T-Zell-Lymphome, dem anaplastisch groĂzelligen T-Zell-
Lymphom sowie dem Sezary-Syndrom, identifiziert werden, die zur malignen
Transformation beitragen. Die Analyse des immunhistologischen PhÀnotyps
primÀrer ZNS-Lymphome (PCNSL) bestÀtigte den aktivierten B-Zell-PhÀnotyp und
den Post-Keimzentrums-Ursprung der PZNSL. Zudem konnte eine signifikante
prognostische Bedeutung des BCL-6-Expressionsstatus bei Patienten mit PZNSL
nachgewiesen werden. Weiterhin konnten wir zeigen, dass sich das Zytokin
Osteopontin in hoher Konzentration im Liquor von Patienten mit ZNSL nachweisen
lÀsst und eine diagnostische und prognostische Aussagekraft besitzt. Die hier
vorgestellten Ergebnisse erweitern das molekulare VerstÀndnis der Lymphom-
Pathogenese mit Ansatzpunkten fĂŒr die Entwicklung neuer Therapiestrategien.
Gleichzeitig zeigen sie am Beispiel von ZNS-Lymphomen die Bedeutung
molekularer Faktoren und Zytokine als diagnostische und prognostische
Biomarker.Human lymphomas and leukemias are characterized by aberrantly activated
transcription factors and cytokine expression. In classical Hdgkin lymphoma
(HL), a common B-cellâderived malignancy that is one of the most prominent
examples for complex patterns of deregulated TFs, we identified IRF5 as major
regulater of deregulated cytokine and chemokine expression in HL. We further
demonstrate that the aberantly expressed cytokine IL-21 protects HL cells from
CD95 death receptorâinduced apoptosis and attracts regulatory T-cells.
Furthermore, we could show that LTR derepression is involved in the
pathogenesis of HL, a finding that might have diagnostic, prognostic and
therapeutic implications
Cytokine and proinflammatory gene expression in classical Hodgkin lymphoma:Its more than NF-ÎșB!
Gene deregulation and spatial genome reorganization near breakpoints prior to formation of translocations in anaplastic large cell lymphoma
Although the identification and characterization of translocations have rapidly increased, little is known about the mechanisms of how translocations occur in vivo. We used anaplastic large cell lymphoma (ALCL) with and without the characteristic t(2;5)(p23;q35) translocation to study the mechanisms of formation of translocations and of ALCL transformation. We report deregulation of several genes located near the ALCL translocation breakpoint, regardless of whether the tumor contains the t(2;5). The affected genes include the oncogenic transcription factor Fra2 (located on 2p23), the HLH protein Id2 (2p25), and the oncogenic tyrosine kinase CSF1-receptor (5q33.1). Their up-regulation promotes cell survival and repression of T cell-specific gene expression programs that are characteristic for ALCL. The deregulated genes are in spatial proximity within the nuclear space of t(2;5)-negative ALCL cells, facilitating their translocation on induction of double-strand breaks. These data suggest that deregulation of breakpoint-proximal genes occurs before the formation of translocations, and that aberrant transcriptional activity of genomic regions is linked to their propensity to undergo chromosomal translocations. Also, our data demonstrate that deregulation of breakpoint-proximal genes has a key role in ALCL