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Aberrant α-synuclein (α-Syn) accumulation resulting from proteasome dysfunction is considered as a prominent factor to initiate and aggravate the neurodegeneration in Parkinson's disease (PD). Although the involvement of 26S proteasome in proteostasis imbalance has been widely accepted, our knowledge about the regulation of immunoproteasome function and its potential role in α-Syn pathology remains limited. Immunoproteasome abundance and proteolytic activities depend on the finely tuned assembly process, especially β-ring formation mediated by the only well-known chaperone proteasome maturation protein (POMP). Here, we identified that α-Syn overexpression was associated with a reduction in immunoproteasome function, which in turn limited the degradation of polo-like kinase 2 (PLK2), exacerbated α-Syn Ser129 phosphorylation and aggregation, ultimately leading to the neurodegeneration. These effects could be dramatically attenuated by β5i overexpression. Mechanistically, α-Syn suppressed the transcriptional regulation of POMP by nuclear factor erythroid 2-related factor 2 (NRF2), thereby preventing the assembly of immunoproteasome β subunits. Dopaminergic neurons-specific overexpression of NRF2-POMP axis effectively rescued the aggregation of α-Syn and PD-like phenotypes. These findings characterized abnormal immunoproteasome assembly as a key contributor governing α-Syn accumulation and neurodegeneration, which might open up a new perspective for the implication of immunoproteasome in PD and provide approaches of manipulating immunoproteasome assembly for therapeutic purposes., Graphical abstract Image 1, Highlights • α-Syn negatively regulated immunoproteasome by inhibiting POMP-mediated assembly. • Immunoproteasome deficiency prevented PLK2 degradation to aggravate neurotoxicity. • Enhanced immunoproteasome assembly via NRF2-POMP axis alleviated α-Syn pathology.

While multiple myeloma (MM) treatment with proteasome inhibitors and other agents yields encouraging results, primary and secondary resistance remains an emerging problem. An important factor in such treatment resistance is the overexpression of several proteins. The present study comprehensively evaluates the expression of POMP, PSMB5, NRF2, XBP1, cMAF and MAFb proteins in plasma cells isolated from the bone marrow of 39 MM patients treated with bortezomib-based regimens using an enzyme-linked immunosorbent assay (ELISA). The proteins were selected on the basis of previous laboratory and clinical studies in bortezomib-treated MM patients. It was found that the expression of the investigated proteins did not significantly differ between bortezomib-sensitive and bortezomib-refractory patients. However, the expression of some proteins correlated with overall survival (OS), this was significantly shorter in patients with higher POMP expression (HR 2.8, 95% CI: 1.1–7.0, p = 0.0277) and longer in those with higher MAFB expression (HR 0.32, 95% CI: 0.13–0.80, p = 0.0147). Our results indicate that a high expression of POMP and MAFB in MM plasma cells may serve as predictors of OS in MM patients treated with bortezomib-based regimens. However, further studies are needed to determine the role of these factors in effective strategies for improving anti-myeloma therapy.

Proteasome inhibitors, like bortezomib, play a key role in the treatment of multiple myeloma (MM), however, most patients eventually relapse and eventually show multiple drug resistance, and the molecular mechanisms of this resistance remain unclear. The aim of our study is to assess the expression of previously described genes that may influence the resistance to bortezomib treatment at the mRNA level (ABCB1, CXCR4, MAF, MARCKS, POMP, PSMB5, RPL5, TXN, and XBP1) and prognosis of MM patients. mRNA expression was determined in 73 MM patients treated with bortezomib-based regimens (30 bortzomib-sensitive and 43 bortezomib-refractory patients) and 11 healthy controls. RPL5 was significantly down-regulated in multiple myeloma patients as compared with healthy controls. Moreover, POMP was significantly up-regulated in MM patients refractory to bortezomib-based treatment. In multivariate analysis, high expression of PSMB5 and CXCR and autologous stem cell transplantation were independent predictors of progression-free survival, and high expression of POMP and RPL5 was associated with shorter overall survival.

[EN] I analyze the symbolism of the chest jewels that women wore at festivals and solemnities in the viceroyalty of Peru, during the first years of the 18th century. An adjacent reading that is based on a double synecdoche, considering women’s hearts as metaphors for loyalty and their chest jewels as a political symbol and part of the total festive simulacrum. Specifically, I will take the entries that the Diario de noticias sobresalientes en Lima y noticias de Europa (1700-1711) collects., [ES] Este trabajo analiza la simbología de las joyas de pecho que lucían las mujeres en las fiestas y solemnidades en el virreinato del Perú, durante los primeros años del siglo XVIII. Es una lectura adyacente que se basa en una doble sinécdoque, al considerar los corazones de las mujeres como metáforas de lealtad y sus joyas de pecho como símbolo político y parte del simulacro festivo total. En concreto, tomaré las entradas que recoge el Diario de noticias sobresalientes en Lima y noticias de Europa (1700-1711)., Este texto forma parte del Proyecto de Investigación «En los bordes del archivo II: escrituras efímeras desde los virreinatos de Indias» (FFI2015-63878-C2-2-P) financiado por el Ministerio de Ciencia, Inno- vación y Universidades de España.

The objective of this study was to determine the correlation between single-nucleotide polymorphism rs4769628 in POMP gene and the development of allergic disease in children. Methods. Genotyping of single nucleotide polymorphism rs4769628 in POMP gene in children with manifestations of atopic march and apparently healthy children using real-time polymerase chain reaction. Results. 62.26 % of children with atopic diseases and 53.06 % healthy children had major allele rs4769628 in POMP gene. 33.67 and 37.76 % of children, respectively, had heterozygous AG variant. Minor GG genotype was not detected in children with atopic diseases, 9.18 % of healthy people are carriers of minor allele (р < 0.05). Conclusions. Minor G allele of rs4769628 in РОМР gene is associated with reduced risk of atopic diseases in children. Polymorphism rs4769628 in РОМР gene can be used as an important prognostic marker for the development of atopic diseases in children., Целью данного исследования было определить связь однонуклеотидного полиморфизма rs4769628 гена РОМР с развитием атопических заболеваний у детей. Методы: генотипирование полиморфизма rs4769628 гена POMP у детей с манифестацией атопического марша и практически здоровых детей с помощью ПЦР в реальном времени. Результаты. У 62,26 % детей с атопическими заболеваниями и у 53,06 % здоровых детей встречается мажорная аллель rs4769628 гена РОМР. 33,67 и 37,76 % детей соответственно имеют гетерозиготний вариант АG. Минорный генотип GG у детей, страдающих атопическими заболеваниями, не встречается, 9,18 % здоровых особей являются носителями минорной аллели (р, Метою даного дослідження було визначити зв’язок між наявністю однонуклеотидного поліморфізму rs4769628 гена РОМР та розвитком алергічних захворювань у дітей. Методи: генотипування поліморфізму rs4769628 гена POMP у дітей з маніфестацією атопічного маршу та практично здорових дітей із застосуванням методики ПЛР в реальному часі. Результати. У 62,26 % дітей, хворих на атопічні захворювання, і 53,06 % здорових дітей зустрічається мажорна алель rs4769628 гена РОМР. 33,67 % і 37,76 % дітей відповідно мають гетерозиготний варіант АG. Мінорний генотип GG у дітей, хворих на атопічні захворювання, не зустрічається, 9,18 % здорових осіб є носіями мінорної алелі (р < 0,05). Висновки. Мінорна алель G rs4769628 гена РОМР асоційована зі зниженим ризиком розвитку атопічних захворювань у дітей. Поліморфізм rs4769628 гена РОМР може використовуватись як важливий прогностичний маркер розвитку атопічних захворювань у дітей.

Regulation of proteasome abundance to meet cell needs under stress conditions is critical for maintaining cellular homeostasis. However, the effects of aging on this homeostatic response remain unknown. In this report, we analyzed in young and aged rat hippocampus, the dynamics of proteasome recovery induced by proteasome stress. Proteasome inhibition in young rats leads to an early and coordinate transcriptional and translational up-regulation of both the catalytic subunits of constitutive proteasome and the proteasome maturation protein. By contrast, aged rats up-regulated the inducible catalytic subunits and showed a lower and shorter expression of proteasome maturation protein. This resulted in a faster recovery of proteasome activity in young rats. Importantly, proteasome inhibition highly affected pyramidal cells, leading to the accumulation of ubiquitinated proteins in perinuclear regions of aged, but not young pyramidal neurons. These data strongly suggest that age-dependent differences in proteasome level and composition could contribute to neurodegeneration induced by proteasome dysfunction in normal and pathological aging. © 2012 International Society for Neurochemistry., This work was supported by grant PS09/00848 (to DR)from the Carlos III Health Institute, Spain. CP was recipient of afellowship from the Spanish Ministry of Education and Science(MEC), Spain. EG is supported by a fellowship from JA and MPGby a Juan de la Cierva contract from MICINN, Spain.

Monogenic disorders, i.e., disorders caused by mutations in a single gene, are rare and clinically heterogeneous conditions. Identification of the genetic cause of monogenic traits can bring new insights into molecular pathways and disease mechanisms. The aims of the present study were to identify the mutant genes in two autosomal recessive skin disorders and to characterize the functions of the mutated genes. In order to identify candidate genes for the two disorders whole-genome SNP analysis, homozygosity mapping and gene sequencing were used. Autosomal recessive congenital ichthyosis (ARCI) is a group of disorders characterized by extensive scaling and redness of the skin. A subgroup of ARCI patients (n=27) was selected based on specific ultrastructural aberrations in their skin, revealed by electron microscopy. Mutations were identified in the Ichthyin gene in 93% of the selected patients, indicating a strong association between mutant Ichthyin and the specific morphological abnormalities. Ichthyin mRNA levels were shown to increase during keratinocyte differentiation in cells from healthy and affected individuals. Electron microscopy revealed a localization of ichthyin protein to keratins and desmosomes in epidermis. Staining of epidermal lipids identified aberrant lipid aggregates in skin sections of patients with Ichthyin mutations, indicating a role for Ichthyin in epidermal lipid metabolism. In twelve KLICK syndrome patients with ichthyosis, palmoplantar keratoderma and keratotic striae on joints, a single-nucleotide deletion was identified in the 5’ region of the proteasome maturation protein (POMP) gene. The deletion caused an increase in the proportion of POMP transcripts with long 5’ UTR’s in patient keratinocytes. Immunohistochemical analysis of differentiated skin cell layers revealed aberrant expression of POMP, proteasome subunits and the skin protein filaggrin in patients. CHOP expression, associated with endoplasmic reticulum stress, was increased in the same layers. siRNA silencing of POMP in cell cultures reduced proteasome subunit levels and induced expression of CHOP. The results indicate that the mutation in KLICK patients causes POMP and proteasome insufficiency with subsequent cellular stress. This study conclusively contributes to the understanding of epidermal physiology and the pathogenesis of two inherited skin diseases.

Das Proteasomsystem ist die Hauptquelle von Peptiden für die MHC Klasse I Antigen-Präsentation. In Vertebraten kann dieses durch die Expression verschiedener Subtypen des 20S Proteasoms moduliert werden. Die häufigsten Subtypen sind konstitutive Proteasomen (c20S) mit den katalytischen Untereinheiten beta1, beta2 und beta5 und Immunoproteasomen (i20S) mit den Immunountereinheiten beta1i, beta2i und beta5i. Die Expression von i20S optimiert in der Regel die MHC Klasse I Antigen-Präsentation, indem die Bildung von Peptiden mit hoher Affinität zu MHC I Molekülen verstärkt wird. Die Bildung von i20S wird momentan durch ein Modell der kooperativen Assemblierung erklärt, das auf der präferentiellen Interaktion zwischen den Immunountereinheiten beruht. In dieser Arbeit wurde die Assemblierung von 20S Proteasomen in beta5i defizienten Mäusen nach Infektion mit Listeria monocytogenes analysiert. In diesem Modell konnte keine präferentielle Interaktion zwischen den Untereinheiten festgestellt werden. Stattdessen zeigen die Ergebnisse, daß die Integration von konstitutiven oder Immunountereinheiten durch direkte Kompetition reguliert wird. Des Weiteren wurde während der Infektion eine beta5i-abhängige Zunahme der zellulären Proteasommenge festgestellt und somit ein neuer Mechanismus zur Regulation des zellulären Proteasomgehaltes entdeckt. Funktionell führt die beta5i-Defizienz zu einer verringerten MHC I Expression auf antigenpräsentierenden Zellen und zu einer verminderten Prozessierung des bakteriellen Antigens LLO296-304. Bei der Analyse der LLO296-304 spezifischen CD8 T Zell Antwort konnte jedoch kein Unterschied zwischen Wildtyp- und beta5i defizienten Mäusen festgestellt werden .Die Kontrolle der Infektion in den beta5i defizienten Mäusen ist jedoch in der Leber verzögert. Dies deutet darauf hin, dass die Erkennung und Elimination infizierter Zellen durch cytotoxische CD8 T Zellen auf Grund der geringeren MHC Klasse I Präsentation bakterieller Antigene behindert wird. The proteasome-system is the main source of peptides for MHC class I antigen presentation. In vertebrates this system can be modulated by the expression of different subtypes of the 20S proteasome. The most common subtypes are constitutive proteasomes (c20S) with the catalytic subunits beta1, beta2 and beta5 and immunoproteasomes (i20S) with the immunosubunits beta1i, beta2i and beta5i. Expression of i20S generally optimizes MHC class I antigen presentation by increasing the generation of peptides with high affinity to MHC class I molecules. Currently, the formation of i20S is explained by a model of cooperative proteasome assembly, which is based on preferential interactions among the immunosubunits. Here, the assembly of 20S proteasomes was analysed in beta5i deficient mice during an ongoing infection with Listeria monocytogenes. In this model, no preferential interactions among constitutive subunits or immunosubunits could be determined. Instead, the results show that the integration of constitutive subunits or immunosubunits is regulated by direct competition. Further, a beta5i-dependent increase in cellular proteasome quantity was observed following infection. This reveals a novel mechanism for the regulation of cellular proteasome quantity, which is based on the differential expression of beta5i. Functionally, the deficiency in beta5i results in a reduced MHC class I cell surface expression on professional antigen presenting cells and a drastically diminished processing of the bacterial antigen LLO296-304. However, the analyses of LLO296-304 specific CD8 T cells did not reveal differences in the frequencies of these T cells between wild-type and beta5i deficient mice. Still, the control of infection in the liver of beta5i deficient mice was delayed. This phenotype suggests that the recognition and elimination of infected target cells by cytotoxic CD8 T cells is constrained due to the lowered MHC class I presentation of bacterial antigens.

Titelblatt und Inhaltsverzeichnis Einleitung Ergebnisse und Diskussion Literaturverzeichnis, Für die intrazelluläre Homöostase und Aktivität energieabhängiger Proteolysesysteme in Pro- und Eukaryonten ist eine strenge Kontrolle essentiell. Während eubakterielle Clp-Proteasen weitestgehend nur über differentielle Genexpression kontrolliert werden, werden die eukaryontischen 26S Proteasomen sowohl über Genexpression als auch über den Einbau und die Aktivierungskinetik ihrer aktiven b-Untereinheiten reguliert. Wir konnten zeigen, dass in Gram-positiven Bakterien die Proteasen ClpCP und ClpEP negativ durch die differentielle Stabilität des CtsR Repressors reguliert werden. Säugerzellen sind in der Lage, ein Absenken der proteasomalen Enzymaktivität durch die Neuformation von Proteasomen in einem positiven autoregulatorischen feed-back Mechanismus zu kompensieren. Ein komplexes und immer noch nicht vollständig verstandenes Biogeneseprogramm, das die Biosynthese aller Untereinheiten und deren Assemblierung und Maturierung umfasst, führt zur Bildung von konstitutiven (c20S) oder Immunoproteasomen (i20S). Das Helferprotein POMP ist dabei essentiell für die koordinierte Rekrutierung und Prozessierung der beta-Untereinheiten. Zwei Hemiproteasom-Intermediate dimerisieren unter Konformationsänderungen zum Preholoproteasom-Intermediat, wo die finale Reifung unter Freisetzung der aktiven Zentren und die Degradierung von POMP stattfindet. Interferon-gamma induziert POMP und die Immunountereinheiten, die nach einem prinzipiell gleichen Schema zu i20S assemblieren. Die Dynamik des Prozesses wird durch die schnelle Aktivierung von beta5i/LMP7 und die sofortige beta5i/LMP7-abhängige Degradation von POMP bestimmt. Infolge dieser molekularen Interaktionen ist die Biogenese von i20S etwa vierfach schneller als die von c20S. i20S besitzen allerdings auch im Vergleich zu c20S eine wesentlich kürzere Halbwertszeit, so dass es sich bei der i20S Biogenese um eine transiente Antwort handelt. Viren und maligne entartete Zellen haben Strategien entwickelt, um einer effizienten Eliminierung durch das Immunsystem zu entgehen. So trägt die Blockierung der Proteasomenaktivität von HIV-Tat in vivo durch direkte Interaktion mit a- und b-Untereinheiten direkt zum immune escape des HI-Virus bei. Ein neuer Mechanismus, der zum Prozess der Onkogenese beiträgt, wurde für humane Tumorzelllinien beschrieben. Die preferentielle Expression der nichtfunktionellen beta5i-Isoform LMP7_E1 in humanen Tumorzellen resultiert in beta5i/LMP7-Mangel und daraus folgend in i20S-Defizienz., A stringent control of the intracellular balance and activity of energy- dependent proteolysis systems is vital for pro- and eukaryotic cells. While eubacterial Clp-proteases are mainly controlled by gene expression, eukaryotic 26S proteasomes can be controlled by gene-expression as well by the incorporation and activation dynamics of their active beta-subunits. We reported, that the proteases ClpCP and ClpEP in Gram-positive bacteria are negatively regulated by the differential stability of the CtsR repressor. Mammalian cells are able to compensate for the inhibition of intracellular proteasomal activity by de novo formation of proteasome complexes in a positive autoregulatory feed-back loop. Both, constitutive (c20S) as well as immunoproteasomes (i20S) are exclusively formed de novo following a sophisticated and not yet fully understood biogenesis program involving the biosynthesis of all subunits, their assembly and maturation processes. Importantly, biogenesis of eukaryotic 20S complexes is assisted by helper factors. The proteasome maturation protein POMP is essentially required for coordination of the recruitment of the beta-subunit proforms and their processing by a cis- and trans autocatalysis. Final activation of the beta- subunits requires the formation of the preholoproteasome assembly intermediate by dimerization of two hemiproteasome intermediates that undergo structural rearrangements. Concomitantly, the cis and trans-autocatalytic removal of the beta-subunit-propeptides liberates the active site threonines of the now fully active 20S core proteasome. At this stage the degradation of POMP signals the successful completion of the proteasome biogenesis program. Assembly of i20S basically follows the same principle after the coincident induction of POMP and the three immunosubunits by Interferon-gamma. The dynamics of this process is determined by the rapid activation of beta5i/ LMP7 and the immediate beta5i/LMP7-dependent degradation of POMP. The molecular interplay between POMP and the beta5i subunit LMP7 essentially accelerate immunoproteasome biogenesis compared to constitutive 20S proteasome assembly nearly four-fold. Moreover, i20S formation is a transient response, since immunoproteasomes exhibit a considerably shortened half-life compared to constitutive proteasomes. Viruses and malignant cells have developed strategies to escape elimination of the immune system. The inhibition of proteasome activity in cells by HIV-1 Tat through direct interaction with alpha- and beta-subunits contributes to the immune escape of the HI-virus. In addition, we described a novel mechanism that supports to the process of oncogenesis. Human cancer cells preferentially express the non-functional immunosubunit-variant LMP7E1, which results in i20S deficiency.

Das 20S Proteasom bildet den Protein degradierenden Teil des Ubiquitin-Proteasom-Systems (UPS) und ist damit an wichtigen zellulären Prozessen wie Genexpressionskontrolle, Zellzykluskontrolle, Apoptose, Peptidgenerierung zur MHC Klasse I Präsentation und Degradation fehlgefalteter Proteine beteiligt. Die einzelnen Schritte der Biogenese des 20S Proteasoms in Eukaryoten sind bisher nur in Ansätzen verstanden. In dieser Arbeit wird die Untereinheitenzusammensetzung von Biogeneseintermediaten und ihre subzelluläre Lokalisation und Organisation in humanen Zelllinien untersucht. Durch die Etablierung eines in vitro Systems konnten distinkte Assemblierungsintermediate humaner Proteasomen generiert werden und ein (-Ring als früheres Intermediat im in vitro System nachgewiesen werden. Aufschluss über den weiteren Vorgang der Assemblierung wurden durch in vivo Experimente mit radioaktiv markierten HeLa Zellextrakten gewonnen. So konnten vor allem neu synthetisierte und zuletzt eingebaute Untereinheiten identifiziert werden. Hierzu gehören die Untereinheiten ?1 und (7, die aufgrund ihrer in trans agierenden C-terminalen Verlängerungen einen Dimerisierungsprozess zweier Halbproteasom-Vorläuferkomplexe forcieren. Darüber hinaus kann die Untereinheit (1 aufgrund der gewonnen Erkenntnisse als die wahrscheinlich den (-Ring schließende Untereinheit im Vorläuferkomplex postuliert werden. Proteasomale Assemblierungsintermediate konnten außerdem durch immuncytochemische und biochemische Methoden am ER von humanen Zelllinien lokalisiert werden. Dabei scheint dem Assemblierungsfaktor POMP eine Schlüsselrolle zuzukommen, da dieser eine Assoziation der Vorläuferkomplexe mit dem ER erst ermöglicht. In dieser Arbeit sind weitere Schritte des komplexen Biogenese-Vorgangs konstitutiver 20S Proteasomen in humanen Zelllinien aufgeklärt worden und es konnte erstmals die subzelluläre Lokalisation für Assemblierungsintermediate in humanen Zellen beschrieben werden., The 20S Proteasom represents the protein degrading part of the Ubiquitin- Proteasom- System and is therefore a participant in important cellular processes like gene expression, cell cycle control, apoptosis, peptide generation for MHC class I presentation and degradation of misfolded proteins. Only the beginnings of the individual steps of the 20S proteasome biogenesis in eucaryotes are so far understood. Tis work examines the subunit composition of assembly intermediates and their subcellular localisation and organisation in eucaryotic cells. Distinct assembly intermediates of human proteasomes have been generated by establishing an in vitro system. As an earlier intermediate in the in vitro system an (-ring could be identified. In vivo experiments using radioactive marked total lysates of HeLa cells shed light on the following sequence of assembly. Thus new synthesised and finally incorporated subunits could be indentified. Two of this subunits are (1 and (7 which could force the dimerisation process of two half-proteasome-precursor by their trans acting c-terminal extensions. Furthermore the (1 subunit has been identified as the (-ring completing subunit in the precursor complex. In addition it was possible to detect proteasomal assembly intermediates through immuncytochemical and biochemical methods on the ER of human cell lines. Thereby the assembly factor POMP plays a key role as it allows in the first place the precursor association with the ER. This work clarifies further steps of complex procedure of biogenesis of constitutive 20S proteasomes in human cell lines and allows the characterisation of the subcellular localisation of assembly intermediates in human cells for the first time.

Das Proteasom spielt eine zentrale Rolle beim Proteinabbau und der Antigen-Generierung für die adaptive Immunantwort. Vertebraten exprimieren zwei Typen des proteolytischen 20S-Kernkomplexes: das konstitutive c20S (mit den aktiven Untereinheiten beta 1, 2, 5) und das Immunoproteasom i20S (mit den Immunountereinheiten LMP2, MECL-1, LMP7). Die i20S-Expression wird durch Interferon_gamma (IFNg) induziert, was die Antigen-Präsentation auf MHC Klasse I und die Immunantwort gegen infizierte bzw. maligne entartete Zellen durch cytotoxische T-Zellen steigert. Proteasomen werden über komplexe, bisher unvollständig verstandene Biogenese-Prozesse formiert. Die initialen Schritte der humanen 20S-Formation wurden in dieser Arbeit untersucht und eine Methode zur Isolation früher Assemblierungsintermediate (EPIs) etabliert. Die 20S-Biogenese bedarf der Assistenz von Hilfsfaktoren wie dem Proteasom-Maturierungsprotein POMP. Diese Komponente von Precursorkomplexen stellt das erste Substrat gereifter c20S dar. In dieser Arbeit konnte erstmalig gezeigt werden, dass POMP ebenfalls die i20S-Formation vermittelt und sich die Biogenese von c20S und i20S hinsichtlich der Maturierungskinetik unterscheidet. POMP wird durch IFNg induziert und interagiert mit der Immunountereinheit LMP7. Dieses molekulare Zusammenspiel bewirkt eine schnellere Maturierung von i20S- im Vergleich zu c20S- Precursorkomplexen, wodurch POMP einem schnelleren Abbau unterliegt. Die forcierte i20S-Biogenese ist eine intrinsische Eigenschaft und unabhängig von weiteren, IFNg-induzierten Faktoren. Nur die LMP7_E2-Variante vermittelt die schnelle Degradation von POMP, während das nicht funktionelle LMP7_E1 mit einer anderen Prosequenz nicht in i20S-Vorläufer inkorporiert wird. Somit führt die alleinige LMP7_E1-Expression in IFNg-stimulierten Carcinom-Zellen zu einer i20S-Defizienz, was eine mögliche Immunevasions-Strategie darstellt. Weiterhin besitzen beide 20S-Typen unterschiedliche Halbwertszeiten: i20S sind, unabhängig von weiteren IFNg-induzierten Proteinen, signifikant instabiler als c20S. Somit werden i20S sowohl schneller formiert als auch zügiger wieder abgebaut als c20S, womit sie typische Eigenschaften cytokin-regulierter Proteine aufweisen. Die i20S-Formation ist also eine transiente Antwort und stellt ein effizientes Instrument zur schnellen Reaktion auf immunologische Herausforderungen wie z.B. eine Infektion dar. Nach einer wirksamen Immunantwort erlaubt die geringere i20S-Stabilität eine schnelle Rückkehr zur standardmäßigen c20S-Expression. The proteasome plays a crucial role in protein degradation and antigen generation for the adaptive immune response. Vertebrates express two types of the proteolytic 20S core complex: the constitutive proteasome c20S (with the active subunits beta 1, 2 and 5) and the immunoproteasome i20S (with the immunosubunits LMP2, MECL-1 and LMP7). Interferon_gamma (IFNg) induces the i20S expression, that supports a more efficient MHC class I antigen presentation and an effective immune response against infected or malignant cells by cytotoxic T-cells. Proteasomes are formed by a complex and not well understood biogenesis program. The initial steps in the human 20S formation have been analyzed in this thesis and a method for the isolation of ´early proteasome assembly intermediates´ (EPIs) has been established. The 20S biogenesis requires the assistance of accessory factors like the proteasome maturation protein POMP. This component of precursor complexes becomes the first substrate of the matured c20S. The described experiments demonstrate for the first time that POMP mediates the i20S formation and that biogenesis of c20S and i20S differ in their maturation kinetics. POMP is induced by IFNg and interacts with the immunosubunit LMP7. This molecular interplay provokes a faster maturation of i20S compared to c20S precursor complexes, whereby POMP becomes subject to a faster degradation. The accelerated i20S biogenesis is an intrinsic characteristic and independent of additional IFNg-induced factors. Exclusively the LMP7_E2 variant causes the rapid degradation of POMP, whereas the non-functional LMP7_E1 bearing another prosequence is not incorporated into i20S precursor complexes. Thus, LMP7_E1 expression in IFNg-stimulated carcinoma cells leads to a i20S deficiency pointing out a possible immune evasion strategy. In addition, both 20S types display different half-life values: i20S are, independent of other IFNg-induced proteins, significantly less stable than c20S. Thus, i20S are not only faster assembled, but also more quickly decomposed compared to c20S, showing typical attributes of proteins regulated by cytokines. Consequently, i20S formation is a transient response and represents an efficient instrument for a rapid adjustment to varying immunological challenges like an infection. Once the immune response has been effective, the lower stability of i20S permits an expeditious return to the standard c20S expression.

The Cyropaedia is a long text involving many different approaches; and yet there is a major split in the work: the taking of Babylon which, at the end of Book 7, marks the end of Cyrus' military conquest. Indeed, while throughout the first part, the young conqueror was at the head of a kind of "travelling Republic" and was deliberately rejecting the slightest display of luxury, the circumstances turn to be entirely different with the defeat and the fall of the enemy capital town. Cyrus settles down in the palace under Hestia's patronage. The last conquests are swiftly reported in just a few sentences. And then, a crucial pattern appears, the development of which gives a framework to the whole beginning of Book 8: the notion that the sovereign must be very parsimonious and cautious in his public appearances. From then on, the conqueror decides to wear the Median dress, as well as shoes with thick soles, and to make up his eyes.For a long time, scholars have been puzzled by this adoption of Eastern pomp – apparently praised by Xenophon. In order to elude the questions raised by this part of the text, some doubts have sometimes been expressed as to its authenticity. Some interpreters have also avoided the problem by assuming that Xenophon mentioned this episode in order to suggest that he was himself keeping his hero at a distance for moral reasons. I will assume here that this adoption of a foreign ceremonial by Xenophon's hero has a political meaning, and not a moral one. The adoption of Eastern pomp is a new governmental technê, which is related to Cyrus' settling in his palace; it is also linked to his wish to deal with issues of imperial deportment and of territorial security and no longer with military problems. For Xenophon, the problem is to find a good and exact balance between what is required by the ruling of such a huge empire – which obliges the ruler to resort to luxurious pomp – and those requirements imposed by the ruling of his own body – and, especially, the necessary inner asceticism of a good leader.