• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1026
  • 255
  • 199
  • 163
  • 93
  • 47
  • 37
  • 32
  • 18
  • 15
  • 14
  • 13
  • 10
  • 9
  • 9
  • Tagged with
  • 2287
  • 484
  • 367
  • 274
  • 255
  • 229
  • 204
  • 202
  • 189
  • 186
  • 176
  • 161
  • 142
  • 138
  • 137
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Function of IRAK2 in macrophages and HECTD1 in B cells / Funktion von IRAK2 in makrophagen und HECTD1 in B zellen

Joshi, Hemant Kumar January 2021 (has links) (PDF)
The Immune system exerts its response against invading pathogens via a cumulative, sequential cooperation of immune cells coordinated by their secreted products. Immune cells, such as macrophages and dendritic cells (DCs), express toll-like receptors (TLRs) to sense the presence of pathogens through pathogen-associated molecular patterns (PAMPs). The interaction of PAMPs with TLRs elicits a cytosolic signaling cascade that enhances the expression of genes to stimulate inflammation. Interleukin 1 receptor-associated kinase 2 (IRAK2) is a component of the TLR signaling pathway. IRAK2 transduces the TLR signal via a direct interaction with TNF receptor-associated factor 6 (TRAF6) and subsequent enhancement of its ubiquitination. During my PhD thesis, I determined that a 55-amino acid long stretch at the C-terminal end of IRAK2 is important for TLR signaling. Overexpression of C-terminal truncated IRAK2 (IRAK2Δ55) in the murine macrophage cell line RAW 264.7 led to impaired CD40 expression after TLR4 stimulation by Lipopolysaccharide (LPS). I observed attenuated competency of IRAK2Δ55 in restoring a full TLR signaling response i.e. IL-6 secretion, NO production and CD40 expression in IRAK2-deficient RAW cells generated via CRISPR-Cas9 approach. Additionally, diminished TLR4 induced activation of nuclear factor κB (NF-κB) and extracellular signal related kinase (ERK) was observed with IRAK2Δ55 reconstituted RAW cells as compared to cell reconstituted with wildtype IRAK2. IRAK2Δ55 reconstituted RAW cells also exhibited reduced TLR4-induced cell death and phosphorylation of receptor interacting protein kinase 3 (RIP3). Co-immunoprecipitation experiments in HEK 293T cells showed that IRAK2Δ55 was still able to bind to TRAF6 alike IRAK2 but failed to induce ubiquitination of TRAF6. In conclusion, the results suggest that the IRAK2 TRAF6 interaction is not sufficient to sustain full TLR signaling. An C-terminus-dependent unknown molecular mechanism is also involved. Through my PhD work, I also analyzed a B cell lineage-specific HECTD1 knock-out mice. HECTD1 is an E3 ubiquitin ligase for various substrate proteins, such as heat shock protein 90 (HSP90), adenomatous polyposis coli and phosphatidylinositol phosphate kinase type 1 γ. Hsp90 regulates a variety of signaling molecules in NF-κB activation pathways which are essential for an optimal B cell response. HECTD1-deficient pro-B cells developed normally into mature B cells. However, TLR4 stimulated HECTD1-deficient B cells displayed reduced immunoglobulin (Ig) production in in vitro cultures. In addition, mice with HECTD1-deficient B cells showed a diminished Ig response after nitrophenylacetyl-keyhole limpet hemocyanin immunization. Thus, HECTD1 is necessary for efficient Ig secretion. / Auf das Eindringen von Pathogenen in den Körper antwortet das Immunsystem mit einer kumulativen, sequenziellen und wechselseitigen Zusammenarbeit zwischen Immunzellen, ihren Oberflächenrezeptoren sowie den von ihnen sezernierten Mediatoren. Immunzellen, wie Makrophagen und dendritische Zellen (DZ), sind dabei in der Lage mittels Toll-like Rezeptoren (TLRs) das Vorhandensein von Pathogenen über Pathogen-assoziierte molekulare Muster (pathogen-associated molecular patterns, PAMPs) zu detektieren. Die Bindung von PAMPs an TLRs führt über intrazelluläre Signalkaskaden zu einer verstärkten Expression pro-inflammatorischer Gene und damit zur Initiierung einer Immunreaktion. Die Interleukin 1 Rezeptor-assoziierte Kinase 2 (IRAK2) ist einer Komponente der TLR Signalkaskade. IRAK2 bindet direkt an den TNF-Rezeptor-assozierten Faktor 6 (TRAF6), welcher daraufhin verstärkt ubiquitiniert wird. In meiner Promotionsarbeit habe ich einen 55 Aminosäure langen Abschnitt im C-Terminus von IRAK2 identifiziert, der für die Signalleitung von TLRs essentiell ist. Die Überexpression von mutierten IRAK2, dem dieser C-terminale Bereich fehlt (IRAK2∆55), in der murinen Macrophagen Zelllinie RAW 264.7 führte zu einer verminderten Expression von CD40 nach Stimulation des TLR4 durch Lipopolysaccharid (LPS). Wurden IRAK2-defiziente RAW Zellen mit dem mutierten IRAK2∆55 Gen rekonstituiert, zeigten diese Zellen verglichen mit Zellen, die mit dem wildtypischen Gen rekonstituiert wurden, eine verminderte Aktivierung des nuclear factor κB (NF-κB) und der extracellular signal related kinase (ERK) nach Stimulation des TLR4. Ebenso waren die Expression von CD40, die Sekretion von IL-6 und NO gestört. In IRAK2-defizienten und IRAK2∆55 RAW Zellen war eine Reduktion des durch TLR4 induzierten Zelltodes sowie der TLR4-induzierten Phosphorylierung der Rezeptor-interagierenden Proteinkinase 3 (RIP3) zu beobachten. Ko-Immunpräzipitationsexperimente mit HEK 293T Zellen zeigten, dass IRAK2∆55 genauso wie intaktes IRAK2 zwar in der Lage ist, TRAF6 zu binden, aber nicht dessen Ubiquitinylierung zu induzieren. Die Ergebnisse dieser Arbeit zeigen, dass die Interaktion von IRAK2 mit TRAF6 für ein optimales TLR-Signal nicht ausreichend ist und deshalb ein bisher unbekannter Mechanismus an der Signalweiterleitung beteiligt sein muss. Dieser Mechanismus ist vom C-terminalen Ende von IRAK2 abhängig. In einem zweiten Teil meiner Doktorarbeit analysierte ich B-Zellen von Mäusen, in denen HECTD1-spezifisch in der B-Zellentwicklungslinie deletiert wurde. HECTD1 ist eine E3 Ubiquitin-Ligase für zahlreiche Substratproteine, wie bspw. dem Hitzeschock-Protein (heat-shock-protein, HSP90), dem adenomatösen Polyposis coli Protein oder der Phosphatidylinositol Phosphatkinase Typ 1 γ. HSP90 reguliert eine Vielzahl an Signalmolekülen im NF-κB Signalweg, die für eine optimale B-Zell-Antwort wesentlich sind. HECTD1-defiziente pro-B-Zellen entwickelten sich normal zu reifen B-Zellen. Die Stimulation des TLR4 auf HECTD1-defizienten B-Zellen führte in vitro zu einer im Vergleich zu wildtypischen B-Zellen reduzierten Immunglobulin-Sekretion. Eine reduzierte Immunglobulin-Antwort konnte auch in B-Zell-spezifischen hectd1-/- Mäusen beobachtet werden, wenn diese zuvor mit Schlitzschnecken-Hämocyanin (Keyhole Limpet Hemocyanin, NP-KLH) immunisiert wurden. Die reduzierte Produktion von Antikörpern durch HECTD1-defiziente B-Zellen zeigt, dass dieses Protein für diese zentrale Aufgabe von B-Zellen notwendig ist.
42

Identification of Rtg2P Functional Domain Involved in Retrograde Signaling in Saccharomyces Cerevisiae

Jiang, Jian 06 May 2017 (has links)
In S. cerevisiae, the accumulation of dysfunctional mitochondria activates a retrograde signal that is mediated through multiple cytosolic regulators. Central to activation is the cytosolic regulator Rtg2p which through its interaction with Mks1p, promotes the nuclear translocation of Rtg1p/3p. Nuclear localized Rtg1p/3p promotes transcription of target genes. Prior work has shown Rtg2p interaction with Mks1p is required for downstream signaling, however the Mks1p binding site within Rtg2p is unknown. To identify this motif, random mutations were generated in RTG2 and a red-white screening strategy was used to assess 14,001 clones. Sequence analysis identified four mutants with amino acid mutations in the carboxy-terminus of Rtg2p that gave rise to defects in CIT2 transcription and loss of Mks1p interaction. Relative to RTG2, all mutants had reduced Rtg2p protein half-lives. Together these results suggest that the carboxy-terminal domain of Rtg2p is essential for retrograde signaling as it may contain the Mks1p binding site.
43

Impact Of Oxybenzone On Innate Immune Signaling

Medeiros, Brenda S 28 June 2022 (has links)
EDCs are commonly thought to bind or interfere with estrogen, androgen, progesterone, thyroid, and retinoid receptors. Oxybenzone is considered to be an endocrine-disrupting chemical and approximately 97% of people in the United States were found to have BP3 in their urine. This thesis will address how BP3 affects the innate immune system, in particular myeloid cells. My Master’s thesis aims to address two main overarching questions. Does BP3 alter macrophage polarization, cytokine/chemokine secretion, the viability in vitro? Does exposure to BP3 in vivo during pregnancy/lactation affect the RNA expression of cytokines and immunosuppressant factors associated with the myeloid population? It is unknown how BP3 impacts immune subpopulations in a neoplastic setting. Additionally, it is important to consider how these effects may contribute to malignant behaviors. My thesis evaluates the effects of BP3 on the Raw 264.7 cell lines as well as tumor tissues from mice exposed to BP3 during pregnancy and lactation. We hypothesized that BP3 exposures induce changes in myeloid cell interactions in the immune system through ER-mediated mechanisms. We anticipated that BP3 would increase the growth and migration of 4T1 cells through indirect signals imparted by myeloid cell populations. We also hypothesized that there will be a decrease in T cell proliferation following BP3 exposure and an alteration in gene expression consistent with a shift from Th1 to Th2. Finally, we expected that BP3 exposure would increase the number of myeloid cells in mouse tumors. Our research shows that oxybenzone appears to enhance the pro-inflammatory state of RAW264.7 cells and may result in the release of unidentified factors that can impact 4T1 cell anchorage-independent cell growth in these pro-inflammatory conditions. BP3 may also impact the metabolic activity of recovering RAW264.7 cells following LPS-induced activity. Additionally, BP3 may impact the release of factors from macrophages that control T cell activation-induced proliferation. By using the p53-/- mouse tumors we found that exposure to 3mg/kg/day BP3 during pregnancy and lactation did alter IDO1 RNA expression but this was not associated with markers of immunosuppressive cell types.
44

A PHOSPHOPROTEOMICS STUDY REVEALS PAK2 AS A THERAPEUTIC TARGET DURING CD44-INDUCED DIFFERENTIATION OF AML CELLS

Jalal Ahmed, Heba M. 05 1900 (has links)
Acute myeloid leukemia (AML) is a clonal malignant disease characterized by a blockage in the differentiation of myeloid cells resulting in the accumulation of highly proliferating immature blast cells. With the success of All Trans Retinoic acid (ATRA) in acute promyelocytic leukemia (AML3), differentiation therapy has become a very attractive treatment option. Ligation of CD44 (a cell surface antigen) with anti-CD44 monoclonal antibodies (mAbs) is reported to reverse the blockage of differentiation and suppress the proliferation of blasts derived from most AML subtypes. However, the molecular mechanisms underlying this apparent ‘normalization’ (reversal) of AML cells induced by CD44 have not been fully elucidated. To expand our understanding of the cellular regulation and circuitry involved, we aimed to apply a quantitative phosphoproteomic approach using Stable Isotope Labeling with Amino acids in Cell culture (SILAC) to monitor dynamic changes of phosphorylation states in HL60 cells following treatment with CD44-mAbs. Phosphoproteomic analysis identified differentially phosphorylated proteins among CD44-mAb treated and control HL60 cells that are involved in a number of major signaling pathways as determined by the Ingenuity Pathway analysis (IPA®) platform. Among others, Rho signaling emerged as a major pathway significantly changed by CD44-mAb treatment. Rho GTPases are well-recognized regulators of the actin cytoskeleton but have also been implicated in diverse cellular events such as cell polarity, microtubule dynamics, membrane trafficking, transcriptional regulation, cell growth control and development. An interesting Rho family member, PAK2 was identified in our search. PAK2 is a ubiquitously expressed serine/threonine protein kinase, which is a direct target for small GTPases and has been identified as a switch between cell survival and cell death signaling depending on its mode of activation. Western-blot analyses of cell lysates of CD44-mAb treated and control HL60 cells confirmed that the phosphorylation of PAK2 ,as well as protein level,were altered as early as 5 minutes following treatment. PAK2 knockdown decreased the effect of CD44-mAb induction of proliferation and inhibition of proliferation proving its importance for mediating it’s signaling transduction. PAK1, a structural homologue of PAK2 had the opposite effect of augmenting CD44-mAb effects suggesting a different mechanism involved. This specificity is attributed to the specific mode of activation that PAK2 exhibits which is not shared with the rest of PAK group I members. Caspase-mediated cleavage of PAK2 producing pro-apoptotic fragments is hypothesized to be the signaling transduction mediated by CD44-mAb. In-Vivo experiments show that PAK2 is essential for leukemic cell migration to the spleen. Additionally, it proved essential for CD44-mAb inhibition of leukemic cells migration to the spleen. Further validation and characterization of PAK2’s activation mode, phosphorylation dynamics, subcellular localization as well as its role in invivo migration are essential in understanding its role in AML.
45

Entrepreneurial signaling eine theoretische und empirische Analyse des Einflusses von höheren Bildungssignalen und Patenten auf innovative Unternehmensgründungen

Werner, Arndt January 2006 (has links)
Zugl.: Köln, Univ., Diss., 2006
46

Zur Rolle des Signaling bei Unternehmensgründungen eine ökonomische Analyse /

Ten Eikelder, Moritz. January 2008 (has links) (PDF)
Bachelor-Arbeit Univ. St. Gallen, 2008.
47

Exploring Notch signaling pathways for breast cancer treatment

Han, Jianxun 11 1900 (has links)
Breast cancer is the most common cancer and the leading cause of cancer-related death among Canadian women. Despite improvements in treatment and early detection, there is still a need to develop novel therapies for breast cancer management. Aberrant Notch signaling is tumorigenic and is associated with poor clinical outcomes in breast cancer, as well as in several other types of cancer. Activation of Notch signaling requires -secretase-mediated Notch receptor cleavage. Thus, strategies to inhibit Notch signaling, including -secretase inhibition, are being evaluated for potential anti-tumor effects. The strongest justification for targeting Notch in breast cancer, and more specifically for using -secretase inhibitors, came from two studies that reported that the -secretase inhibitor (GSI) Z-LLNle-CHO inhibited the growth of breast cancer cells both in vitro and in vivo without causing significant side effects. In Chapter 2, we compared the enzymatic activities and cytotoxicity of Z-LLNle-CHO to those of two other specific GSIs and three proteasome inhibitors and demonstrated that the cytotoxicity of Z-LLNle-CHO in breast cancer cells is mediated by proteasome inhibition, not by -secretase inhibition. In Chapter 3, we characterized the protein complexes formed in breast cancer cells by the intracellular domains (NICD) of the four Notch paralogs. We found that the assembly of NICD protein complexes is dose-dependent and availability of MAML proteins becomes the limiting factor for continuous formation of NICD/RBPj/MAML transactivation complex. This suggests that the formation of some non-canonical NICD complex might occur preferentially at high levels of NICD, conditions under which aberrant Notch signaling induces tumorigenesis in breast cancer. Consequently, these non-canonical interactions might be good targets to specifically block oncogenic, but not physiological, Notch signaling. In addition, we found that the relative affinities of individual NICD paralogs to several known NICD-interacting proteins were different. This may account for the paralog-specific activities of Notch that have been previously reported. Together, these results may be of value for the development of new reagents to block Notch signaling for therapeutic benefit in breast cancer treatment. / Experimental Oncology
48

The Role of Myosin Light Chain Kinase and Non Muscle Myosin II In Ras Signaling to ERK

Khan, Protiti 01 January 2008 (has links)
We have previously reported that non-muscle myosin II (NMMII) and myosin light chain kinase (MLCK) are required for oncogenic Ras signaling to ERK in Ki-Ras transformed rat fibroblsasts (Helfman and Pawlak, J. Cell Biochem. 95(5), 1069-80, 2005). Here I examine if MLCK plays a role in ERK signaling in various tumor derived human epithelial cell lines. I also determined whether genetic inhibition of NMMII isoforms IIA and IIB, or MLCK also inhibits ERK activation in the MCF 10A human breast epithelial cell line expressing oncogenic H-Ras. Inhibition of MLCK by pharmacological inhibitors such as ML-7 and ML-9 was used to determine the role of MLCK in ERK signaling in an array of H/K-Ras transformed and tumor derived cell lines: T-24 bladder carcinoma, HCT 116 colon carcinoma, and MCF 10A Ras breast cancer cells. Genetic inhibition was carried out using specific siRNA targeted towards MLCK and NMMIIA or IIB. The knock down of NMM IIA and IIB did not inhibit active ERK, which suggested either a redundant function of NMM IIC or an alternate substrate for MLCK. Inhibition of MLCK by ML-7/ML-9 reduced activated ERK in all H/K-Ras transformed, or human tumor derived cell lines we tested. The possible mechanism of how MLCK could play a role in ERK signaling was tested by co-immunoprecipitation (co-IP) of MAPK scaffolding proteins with MLCK. That the ERK scaffold KSR1 regulates ERK signaling in MCF 10A Ras, was demonstrated through inhibition of KSR1 with siRNA. Moreover, KSR was shown to interact with MLCK because it was found to co-precipitate with MLCK.
49

Insulin signaling, mitochondrial DNA copy number regulation and aging in Caenorhabditis elegans

Hu, Xiaobin 11 1900 (has links)
Mitochondrial dysfunction is considered as a key mechanism of aging but little is known about the impact of mitochondrial biogenesis. Mitochondrial DNA (mtDNA) copy number control is an important aspect of mitochondrial biogenesis and is highly regulated in eukaryotic organisms. By studying mtDNA copy number, our aim is to gain a better understanding of the relationship between mitochondrial biogenesis and aging. We developed an optimized protocol for measuring mtDNA copy number in Caenorhabditis elegans using quantitative real-time PCR (qPCR). We investigated how mtDNA regulation is affected by a variety of aging-related pathways. We found the insulin/IGF-1 signaling (IIS) pathway regulates mtDNA content in a DAF-16- and UCP-4-dependent manner. By utilizing RNA interference (RNAi) against polg-1, we showed that mitochondrial stress likely modulates lifespan through the IIS pathway. Our work identifies IIS as a communications pathway between mitochondria and the nucleus in modulating mitochondrial biogenesis and lifespan in Caenorhabditis elegans.
50

The role of Phosphoinositide 3-Kinase in the Regulation of Cardiac Morphology and Function

Guo, Danny 06 1900 (has links)
The traditional PI3K pathway relies on agonist mediated stimulation of PI3Kα through RTKs and PI3Kγ through GPCRs, which stimulate downstream enzymes such as Akt. This pathway has been found to be important in cardiomyocytes and cardiofibroblasts for regulating cardiac morphology and function. However, evidence has suggested that this traditional pathway does not fully represent the PI3K signaling cascade. We demonstrated that PI3Kγ regulates calcium through kinase independent interactions. PI3KγKO hearts rapidly develop systolic dysfunction and dilated cardiomyopathy in response to pressure overload due to excess matrix metalloproteinase mediated degradation of N-cadherin adhesion complexes. We also show a connection between the PI3K/PTEN and Casein Kinase 2, an enzyme that deactivates PTEN. Finally, our results demonstrate crosstalk between GPCRs and PI3Kα via transactivation of growth factor receptors. Our results provide insight into the regulation and the complexity of the PI3K/PTEN pathway. / Experimental Medicine

Page generated in 0.1357 seconds