Thesis (doctoral)--Ludwig Maximilians-Universität zu München, 1978.

Thesis (doctoral)--Universität Hamburg, 1979.

Thesis (Ph.D.) -- Virginia Commonwealth University, 2006. / Prepared for: Dept. of Microbiology and Immunology. Bibliography: p. 152-184. Also available online.

Lymphocyte activation and trafficking are indispensable to the immune system. CD44, an adhesion molecule, plays important roles in T cell activation, lymphocyte homing/trafficking, and tumor metastasis. Although the functions of CD44 have been shown in T cells and other leukocytes, little is known about its role in B cells. The effects of CD44 cross-linking on murine B cell activation via CD40L/IL-4 was explored using the anti-CD44 mAbs RK3G9 and IM7. Immobilized RK3G9 and IM7 could strongly inhibit B cell proliferation and Ig production, with IgE inhibition being prominent. Soluble anti-CD44 had no effect. The inhibitory effect of RK3G9 was not influenced by addition of anti-FCγRII, indicating no role for the inhibitory receptor. The effects of delayed addition of immobilized anti-CD44 mAbs were studied, and the results indicated no inhibition after 96 hrs of culture. B cells were also activated by either LPS or anti-IgM F(ab')2. While LPS-induced B cell activation was inhibited by immobilized anti-CD44 mAbs, anti-IgM activation was refractory. Interestingly, addition of both anti-IgM and CD40L or LPS resulted in some modulation of the inhibitory activity. Additionally, FACS and Elispot revealed that RK3G9-treated cells had reduced numbers of plasma cells. Taken together, these results suggest that CD44 cross-linking could control polyclonal B cell activation by CD40L, but allow sIgM/CD40L activation to continue.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 6 uppsatser.

Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (leaves 115-126).

Thesis (Ph. D.)--Cornell University, 1989. / Vita. Includes bibliographical references.

MALA-2 (Murine Lymphocyte Activated Antigen-2) is a murine cell surface antigen that is detected at high concentration on activated, proliferating lymphocytes, but only weakly on resting lymphocytes. It is thought to play an important role in lymphocyte activation since the rat monoclonal antibody YN1/1.7.4 which recognizes MALA-2 is capable of inhibiting the mixed lymphocyte reaction. Considering the central role of lymphocyte activation to the generation and maintenance of the immune response, I undertook the purification and biochemical characterization of MALA-2. In these studies, MALA-2 was isolated and purified to homogeneity using immobilized YN1/1.7.4 monoclonal antibody and sodium docecylsulphate-polyacrylamide gel electrophoresis. Biochemical characterization studies revealed that MALA-2 is a Mr 95-100 kD glycoprotein containing a protein backbone of approximately 66 kD, and N-linked carbohydrate chains amounting to a Mr of approximately 35 kD. Two dimensional gel electrophoresis suggested that MALA-2 has an isoelectric point of 4.9. Although it was previously suspected that MALA-2 might be associated with the transferrin receptor on the cell surface, this was shown not to be the case on NS-1 cells. Additionally, ³²P-orthophosphate labelling of MALA-2 on NS-1 or MBL-2 cells could not be detected. Finally, the partial amino acid sequence of MALA-2 was determined by sequencing trypsin-generated peptides from purified MALA-2. Computer-assisted homology comparisons of the MALA-2 partial amino acid sequences with other known sequences showed that MALA-2 shared its most consistent homology with a class of proteins known as the immunoglobulin superfamily. Subsequent to this study, the partial amino acid sequences obtained within this study were used to construct oligonucleotide probes. These probes were used for the screening of cDNA libraries, facilitating the successful cloning of the MALA-2 gene. This, in turn, resulted in the identification of MALA-2 as the murine counterpart of the human ICAM-1 molecule, a protein known to play a significant role in intercellular adhesion and lymphocyte activation within the immune system. Significantly, results obtained from the biochemical characterization of MALA-2 carried out in this thesis have been confirmed by the subsequent nucleotide sequence data from the cloning of MALA-2. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Le facteur de transcription NF-KB joue un rôle essentiel dans le développement, l’homéostasie, la survie du système immunitaire, mais également dans la propagation de certains lymphomes. L’activation optimale de NF-ΚB en réponse à l’engagement de nombreux immunorécepteurs repose sur la mise en place de larges signalosomes dans lesquels des adaptateurs spécifiques sont recrutés et poly-Ubiquitinylés de façon non-Dégradative. En réponse à des cytokines pro-Inflammatoires ou à l’activation des récepteurs antigéniques, ces adaptateurs ubiquitinylés s’accumulent sur la face cytoplasmique du réticulum endoplasmique (RE) via la protéine du RE metadherine (MTDH) qui assure la propagation du signal NF-KB. Toutefois, la nature des E3 ligases en charge de relayer NF-KB au niveau des organites intracellulaires reste méconnue. C’est pourquoi j’ai réalisé le crible par bioluminescence d’une librairie de siRNA dirigée contre les 46 E3 ubiquitine ligases humaines pourvues d’un domaine transmembranaire qui les ancrent au niveau de différents compartiments cellulaires afin d’étudier leur impact sur l’activation de NF-KB en réponse à une stimulation antigénique dans un modèle de lymphocytes T immortalisés Jurkat. Nous avons identifié la protéine du RE TRIM13 comme un régulateur positif de la signalisation NF-ΚB. Nos données suggèrent un modèle dans lequel TRIM13 régule l’activation de NF-KB en modulant indépendamment l’activation de deux membres clés de la famille NF-KB au cours de l’activation lymphocytaire, RelA (p65) et c-Rel.Lors de cette thèse, j’ai également participé au crible d’une librairie de siRNA ciblant les 96 déubiquitinases (DUBs) codées par le génome humain afin d’identifier celles en charge de ramener les cellules vers leur état basal. Ceci a permis la caractérisation de la protéase spécifique de l’ubiquitine USP34 (Ubiquitin specific protease 34). La réduction des niveaux endogènes de USP34 potentialise l’activation de NF-KB en réponse à l’engagement du récepteur antigénique T ou du récepteur au TNFa et la liaison de NF-KB à l’ADN est accrue. Collectivement, ces résultats suggèrent que USP34 est un nouvel acteur impliqué dans la régulation négative de NF-KB.Ces résultats illustrent l’importance des processus d’ubiquitination réversibles dans la régulation de la signalisation NF-ΚB et introduisent les cribles génétiques comme un outil efficace pour l’identification de régulateurs de processus biologiques divers. / The transcription factor NF-KappaB plays a critical role in the development, homeostasis, the survival of the immune system, but also in the propagation of certain lymphomas. The optimal activation of NF-KappaB in response to the engagement of many immunoreceptors rely on the implementation of large signalosomes where specific adaptors are recruited and poly-Ubiquitinylated in a non-Degradative manner. In response to proinflammatory cytokines or activation of antigen receptors, these Ubiquitinylated adaptors accumulate on the cytoplasmic leaflet of the endoplasmic reticulum (ER) via the ER protein metadherin (MTDH) providing NF-KappaB signal propagation . However, the nature of the E3 ligases responsible for relaying NF-KappaB in intracellular organelles remains unknown. This is why I made the screen ingby bioluminescence of a library of siRNAs targeting the 46 human ubiquitin E3 ligases provided with a transmembrane domain that anchor them at different cellular compartments to study their impact on the NF-KappaB activation in response to antigenic stimulation in immortalized T lymphocytes Jurkat. We identified the ER-Protein TRIM13 as a positive regulator of NF-KappaB signaling. Our data suggest a model in which TRIM13 regulates the activation of NF-KappaB activation by modulating independently two key members of the NF-KappaB family during lymphocyte activation, RelA (p65) and c-Rel. In this thesis, I also participated in the screening of a library of siRNAs targeting the 98 deubiquitinases (DUBs) encoded by the human genome to identify those in charge of the reset of the system to basal state. This screen allowed the characterization of the ubiquitin-Specific protease USP34 (ubiquitin specific protease 34). The reduction of endogenous levels of USP34 potentiates the activation of NF-KappaB in response to engagement of the antigen receptor or T receptor antagonists and enhances NF-KappaB DNA binding. Collectively, these results suggest that USP34 is a new player involved in the negative regulation of NF-KappaB. These results illustrate the importance of reversible ubiquitination process in the regulation of the NF-KappaB signaling and introduce genetic screens as an effective tool to identify regulators of diverse biological processes.