A axila foliar em Passiflora L. (Passifloraceae) apresenta uma estrutura complexa: de um mesmo ponto parecem surgir flores e gavinhas, além de uma gema vegetativa também estar presente. A origem da gavinha foi interpretada de diferentes maneiras ao longo da história, sendo considerada desde modificações de um ramo até uma flor. Além disso, a ontogenia dessas estruturas tem início em um único meristema axilar, que geralmente é descrito como capaz de se dividir em dois ou mais meristemas (chamado de \"complexo de gemas\"), cada qual dando origem a uma estrutura diferente (gavinhas e flores). Estudos de expressão gênica demonstram a presença do ortólogo do gene LEAFY de Arabidopsis, em meristemas axilares, florais e de gavinhas, em duas espécies de Passiflora. Esse gene é tipicamente relacionado à transição de fase vegetativa para reprodutiva em diversas angiospermas. Assim, o presente estudo objetivou descrever em detalhes a ontogenia das diferentes estruturas originadas no meristema axilar de diferentes espécies, focando em diferentes fases de vida da planta, bem como averiguar a expressão de ortólogos de APETALA1 (AP1), um gene tipicamente relacionado à identidade de meristemas florais e na determinação de sépalas e pétalas. Como resultado, propomos uma nova interpretação para a ontogenia do complexo de gemas, baseada na produção de brácteas e seus meristemas associados. Demonstramos também que o ortólogo de AP1 se expressa de maneira mais ampla do que aquela encontrada no modelo Arabidopsis, possivelmente desempenhando diversas funções relacionadas à manutenção da indeterminação celular. / The leaf axil in Passiflora L. (Passifloraceae) bears a complex structure: a tendril and one or more flowers seem to arise from the same growing point. In addition, vegetative bud is also present. There are many different interpretations for the origin of the tendril in this group, ranging from modifications of flowers to side shoots. Also, the ontogeny of these structures is often understood as a single meristem which subdivides into a bud complex, comprising the tendril and flower meristems. Recently, the expression of the LEAFY ortholog was demonstrated in the axillary, tendril and floral meristems of two Passiflora species. In Arabidopsis and many angiosperms, this gene is responsible for the shift between vegetative and reproductive phase. Therefore, the present work aimed to describe, in detail, the ontogeny of the bud complex in Passiflora species belonging to different subgenera, including different life stages. The expression of the ortholog of APETALA1, a gene typically related to floral meristem identity and sepal/petal specification was also assessed. As results, we propose a different interpretation for the ontogeny of the bud complex, based on the production of bracts and their associated meristems by the original axillary meristem, which then turns into the tendril meristem. We also demonstrate that expression of AP1 is much broader than that of the Arabidopsis model, and possibly have many other functions related to cell indeterminacy.

La prééclampsie est une maladie humaine qui affecte 3-8 % des grossesses dans le monde, cliniquement définie par l’apparition de novo d’une hypertension et d’une protéinurie. La cause initiale de la maladie semble être liée à un défaut de vascularisation placentaire, ce qui entraine des cycles d'hypoxie – ré-oxygénation, une ischémie placentaire et la libération de débris placentaires dans la circulation maternelle. Ces derniers sont responsables d'une activation endothéliale généralisée, exacerbée par un état pro-coagulant et pro-inflammatoire. Pour mieux caractériser la réponse des cellules endothéliales aux facteurs plasmatiques présent dans la circulation maternelle des femmes prééclamptiques , nous avons choisi une approche à l’échelle du génome entier pour évaluer le profil d'expression génique (grâce à des puces d’expression) de la lignée de cellules endothéliales humaines de la veine ombilicale (HUVEC) cultivée avec du plasma prééclamptique, comparée au profil de cellules cultivées avec du plasma humain provenant de grossesses normales. Cette étude nous a permis d'identifier différents gènes modulés dont celui codant la protéine de dimérisation Jun 2 (JDP2, diminué près de trois fois) qui pourrait être responsable d'une partie des modifications transcriptomiques trouvées. De façon intéressante en effet, inhiber JDP2 par une approche de siRNA régule significativement à la baisse (entre autres) l'expression du VEGF, imitant ainsi les effets du plasma prééclamptique sur les HUVEC. Dans la dernière partie de mon projet, nous nous sommes particulièrement concentrés sur l'impact de l’inhibition de JDP2 sur des gènes induits par l'hypoxie. La tension partielle basse en oxygène modifie l'expression génique par l'intermédiaire de la stabilisation du facteur de transcription HIF- 1a. En fait, dans un état hypoxique, HIF- 1a échappe à la dégradation par le protéasome, il forme alors des hétérodimères avec ARNT (HIF- 1ß) et induit l'expression de gènes ayant un élément de réponse à l’hypoxie (HRE) dans leur promoteur. L'induction de l'expression du VEGF dans des conditions d’hypoxie constitue un des premiers modèles de l’effet de l’hypoxie sur l’expression génique et c’est également un des mieux caractérisés. Afin d'évaluer le rôle de JDP2 sur l'expression du VEGF, et plus généralement sur des gènes cible de l’hypoxie, nous avons cultivé des cellules HUVEC dans des conditions de normoxie et d’hypoxie. Les mêmes conditions ont été utilisées en association avec la transfection de siRNA contre JDP2. En conclusion, dans des conditions d’hypoxie, l’inhibition de JDP2 a un impact négatif sur l'expression du VEGF. De plus, JDP2 semble être un médiateur essentiel de l'expression génique induite par l'hypoxie, car il est nécessaire à une activité complète de promoteur contenant des HRE (démontré dans des essais luciférase). / Preeclamspia is a unique human disorder which affects 3-8% of pregnancies worldwide, clinically defined as the new onset of hypertension and proteinuria. The root cause of the disease seems to be linked to a defect of placental vascularization, which enhances cycles of hypoxia –reoxygenantion, placental ischemia and the release of placental debris into maternal circulation. The latter ones are responsible for a widespread endothelial activation, exacerbated pro-coagulable and pro-inflammatory state. To best characterize the response of endothelial cells to the plasma factors present in maternal circulation of preeclamptic women, we chose a genome –wide approach in order to evaluate the gene expression profile of Human Umbilical Vein Endothelial Cells (HUVEC) line cultivated with preeclamptic plasma, compared to cells cultivated with human plasma coming from normal pregnancies. This study allows us to identify the gene Jun Dimerization Protein2 (JDP2) which could be responsible for part of transcriptomic modifications. Interestingly inhibiting JDP2 by the use of siRNA significantly down- regulates VEGF expression, thus mimicking the effects of preeclamptic plasma on HUVEC. In the last part of my project we focus specifically on the impact of JDP2 knock down on hypoxia- induced genes. Low oxygen tension modifies gene expression via the stabilization of the transcription factor HIF-1a. In fact under hypoxic condition, HIF-1a escapes from proteasomal degradation, it forms heterodimers with ARNT (HIF- 1ß) and induces the expression of genes having a Hypoxia Responsive Element (HRE) in their promoter. One of the first and best characterized models of the effect of hypoxia on gene expression is the induction of VEGF expression under hypoxic condition. In order to evaluate the contribution of JDP2 to VEGF expression, and more generally to hypoxia target genes, we cultivate HUVEC in normoxic and hypoxic condition. The same conditions were used in association with transfection of siRNA against JDP2. In conclusion, under hypoxic condition, JDP2 down- regulation has a negative impact on VEGF expression. Moreover, JDP2 seems to be an essential mediator of hypoxia –induced gene expression, since it is necessary for a full HRE promoter activity (demonstrated by Luciferase assays).

A axila foliar em Passiflora L. (Passifloraceae) apresenta uma estrutura complexa: de um mesmo ponto parecem surgir flores e gavinhas, além de uma gema vegetativa também estar presente. A origem da gavinha foi interpretada de diferentes maneiras ao longo da história, sendo considerada desde modificações de um ramo até uma flor. Além disso, a ontogenia dessas estruturas tem início em um único meristema axilar, que geralmente é descrito como capaz de se dividir em dois ou mais meristemas (chamado de \"complexo de gemas\"), cada qual dando origem a uma estrutura diferente (gavinhas e flores). Estudos de expressão gênica demonstram a presença do ortólogo do gene LEAFY de Arabidopsis, em meristemas axilares, florais e de gavinhas, em duas espécies de Passiflora. Esse gene é tipicamente relacionado à transição de fase vegetativa para reprodutiva em diversas angiospermas. Assim, o presente estudo objetivou descrever em detalhes a ontogenia das diferentes estruturas originadas no meristema axilar de diferentes espécies, focando em diferentes fases de vida da planta, bem como averiguar a expressão de ortólogos de APETALA1 (AP1), um gene tipicamente relacionado à identidade de meristemas florais e na determinação de sépalas e pétalas. Como resultado, propomos uma nova interpretação para a ontogenia do complexo de gemas, baseada na produção de brácteas e seus meristemas associados. Demonstramos também que o ortólogo de AP1 se expressa de maneira mais ampla do que aquela encontrada no modelo Arabidopsis, possivelmente desempenhando diversas funções relacionadas à manutenção da indeterminação celular. / The leaf axil in Passiflora L. (Passifloraceae) bears a complex structure: a tendril and one or more flowers seem to arise from the same growing point. In addition, vegetative bud is also present. There are many different interpretations for the origin of the tendril in this group, ranging from modifications of flowers to side shoots. Also, the ontogeny of these structures is often understood as a single meristem which subdivides into a bud complex, comprising the tendril and flower meristems. Recently, the expression of the LEAFY ortholog was demonstrated in the axillary, tendril and floral meristems of two Passiflora species. In Arabidopsis and many angiosperms, this gene is responsible for the shift between vegetative and reproductive phase. Therefore, the present work aimed to describe, in detail, the ontogeny of the bud complex in Passiflora species belonging to different subgenera, including different life stages. The expression of the ortholog of APETALA1, a gene typically related to floral meristem identity and sepal/petal specification was also assessed. As results, we propose a different interpretation for the ontogeny of the bud complex, based on the production of bracts and their associated meristems by the original axillary meristem, which then turns into the tendril meristem. We also demonstrate that expression of AP1 is much broader than that of the Arabidopsis model, and possibly have many other functions related to cell indeterminacy.

Glucan is a natural product immunomodulator that has been reported to enhance early wound repair. The mechanism of glucan-stimulated wound repair was thought to be indirect via macrophage release of wound growth factors. However, recent data indicate that there are glucan-specific receptors on human fibroblasts that can modulate cellular function following interaction with the glucan ligand. In this study we examined the effect of glucan on activation of the transcription factors activator protein-1 (AP-1) and specificity protein-1 (Sp1) in normal human dermal fibroblasts. AP-1 and Sp1 are involved in the regulation of cytokine and procollagen genes. In addition, we evaluated the effect of glucan on wound growth factor and vascular endothelial growth factor (VEGF) mRNA expression in primary cultures of normal human dermal fibroblasts. Glucan (1 μg/ml) stimulated fibroblast AP-1 and Sp1 activation in a time-dependent manner, although the temporal kinetics varied between the two transcription factors. AP-1 binding activity was increased (p<0.05) at early time intervals (1, 2, 4, 8 and 12 h), while Sp1 nuclear binding activity was increased (p<0.05) at later time intervals (12, 24, 36 and 48 h). Glucan (1 μg/ml) stimulated fibroblast expression of neurotrophin 3 (NT-3), platelet derived growth factor A (PDGF-A), platelet derived growth factor B (PDGF-B), fibroblast growth factor acidic (aFGF), fibroblast growth factor basic (bFGF), transforming growth factor alpha (TGFα), transforming growth factor beta (TGFβ) and VEGF mRNA at 8 h.

Toxoplasma gondii, l'agent causal de la toxoplasmose appartient au phylum des Apicomplexes. Comme son nom l'indique, le parasite possède un complexe unique d'organites sécrétoires apicaux, les micronèmes, rhoptries et le conoïde, qui jouent un rôle essentiel dans l’invasion de la cellule hôte et la survie du parasite. T. gondii est devenu un modèle populaire de biologie cellulaire et aussi un outil de référence pour l'étude de l’organisation ultra-structurale et des différentes fonctions des autres parasites du phylum Apicomplexa tel que Plasmodium, l’agent causal de la malaria. Cette thèse porte sur deux facteurs essentiels à la survie du parasite : le complexe adapteur de la clathrine AP1 et la petite GTPase Rab11A qui jouent un rôle crucial dans la régulation de certaines voies du trafic intracellulaire de T. gondii. Ainsi, nos travaux ont permis de démontrer un rôle pour AP1 dans le triage différentiel et le transport vésiculaire des protéines MIC et ROP depuis le Trans-Golgi-Network (TGN) et les compartiments endosomaux, respectivement. D’autre part, nos résultats ont révélé un rôle original de AP1 dans la division parasitaire aux stages tardifs de la cytokinèse. Nous avons également identifié un partenaire de AP1, la protéine unique de T. gondii possédant un domaine ENTH : EpsL (pour Espin-Like Protein). Dans les autres Eucaryotes, les protéines epsines sont connues pour activer la formation des vésicules à clathrine en co-opération avec les complexes AP1 et AP2. Nos résultats ont effectivement démontré un rôle de EpsL, similaire à AP1, pour la biogénèse des rhoptries et micronèmes. Nous avons, dans un deuxième temps, examiné les différentes fonctions de la petite GTPase Rab11A. Notre étude par vidéo-microscopie, semble indiquer que Rab11A régule le transport de vésicules depuis le TGN vers la périphérie cellulaire et en particulier, les pôles basal et apical du parasite. Après sur-production de la forme mutée inactive de Rab11A, nous avons démontré un nouveau rôle de la protéine dans la sécrétion des protéines membranaires de surface et dans l'exocytose des granules denses, lors de l'invasion de la cellule hôte mais aussi durant la réplication parasitaire. Finalement, des expériences de pull-down ont permis d’identifier un partenaire intéressant liant Rab11A seulement sous sa forme activée, la protéine unique de T. gondii contenant un domaine HOOK (TgHOOK), que nous avons caractérisée au niveau fonctionnel. Nos résultats suggèrent que TgHOOK régule le transport des vésicules positives pour Rab11A d’une manière dépendante des microtubules. Par conséquent, cette dernière étude a permis de révéler de nouveaux aspects encore inexplorés, bien qu’essentiels, des mécanismes régulant la sécrétion de molécules à la surface parasitaire. / Toxoplasma gondii, the causative agent for the disease Toxoplasmosis belongs to the phylum Apicomplexa. As the name implies, the parasite possesses a unique complex of apical secretory organelles namely the micronemes, rhoptries and conoid, which favor host cell invasion and intracellular survival. T.gondii has become a popular cell biology model and also a reference tool for studying the structure and functions of other important parasites that belong to the same phylum, such as plasmodium, but also higher eukaryotes. The recent advances in dissecting protein trafficking pathways have led to a better understanding of the biogenesis of apical organelles and also to the identification of crucial protein molecules that could determine the fate of the parasite. This thesis focuses on two different molecules, the Clathrin Adaptor complex AP1 and the small GTPase Rab11A that play a crucial role in distinct trafficking pathways of the parasite contributing to a wide range of functions. First, we reveal a role of AP1 in the differential sorting of microneme and rhoptry proteins at the Tran-Golgi-Network and endosomal level, respectively. Accordingly, depletion of AP1 leads to a defect in apical organelle biogenesis. In addition, we reveal an original role of AP1 in parasite division by regulating late stages of cytokinesis. We also identified and studied a partner of AP1, the unique ENTH domain containing protein of the parasite, EpsL (for Espin-like protein). In other Eukaryotes, epsin proteins are well known regulators of clathrin-mediated vesicular budding in co-operation with AP1 and AP2. We demonstrated that EpsL shares similar functions to AP1 in regulating rhoptry and microneme formation. We next worked on the small GTPase Rab11A and defined the dynamics of the protein within the parasite by live imaging. In addition to its known role in cytokinesis, we unravelled a novel function for the molecule in the secretion of surface membrane proteins and the exocytosis of dense granules during both, parasite invasion and replication. Further, pull down experiments on active Rab11A helped us fish an interesting partner molecule, the unique HOOK-domain containing protein that we functionally characterized for the first time in T.gondii. Our data suggest a role of Rab11A in microtubule-dependent transport of vesicules in a HOOK-regulated manner. Therefore, our study provides novel molecular insights into a yet unexplored but essential aspect of constitutive secretion in the parasite.

Value at Risk (VaR) approach has been extensively used by investment and commercial banks since its development by JP Morgan in 1990s. As time passes, it has become interesting to investigate whether VaR could be used also by other financial intermediaries like pension funds and insurance companies. The aim of this paper is to outline Value at Risk (VaR) methodology by giving more emphasis on parametric approach which is used for empirical section and to investigate the applicability and usefulness of VaR in pension funds. After providing theoretical framework for VaR approach, the paper continues with pension fund systems in general and especially highlights AP funds of Swedish National pension fund system by trying to show why VaR could be an invaluable risk management tool for these funds together with other traditional risk measures used. Based on this given theoretical frame, a practical application of VaR –parametric or covariance/variance method- is executed on 50 biggest investments in the fixed income and equity portfolios of three selected Swedish national pension funds – AP1, AP2 and AP3. Results of one day VaR (DEAR) estimations on 30/12/2005 for each fund have been presented and it is aimed to show the additional information that could be obtained by using VaR and which is not always apparent from other risk measures employed by funds. According to the two traditional risk measures which are active risk and Sharpe ratio; AP2 and AP3 lie in the same risk level for 2005 which can create a contradiction by considering their different returns. On the other hand, obtained DEAR estimates show their different risk exposures even with the 50 biggest investments employed. The results give a matching relationship between return of funds and DEAR estimates meaning that; the fund with the highest return has the highest DEAR value and the fund with the lowest return has the lowest DEAR value; which is consistent with the main rule- “higher risk, higher return”. Thus, we can conclude that VaR could be applied additionally to get a better picture about real risk exposures and also to get valuable information on expected possible loss together with other traditional risk measures used. Key words: Value at Risk, DEAR, Pension funds, Risk management, Swedish pension plan, AP1, AP2, AP3

During development, intrinsic genetic programs give rise to distinct cellular lineages through the establishment of cell type specific chromatin states. These distinct chromatin states instruct gene expression primarily through the genome-wide demarcation of enhancers. In addition to maintaining cellular identity, the chromatin state of a cell provides a platform for transcriptional responses to environmental signals. However, relatively little is known about the influence of extracellular stimuli on chromatin state at enhancers, and it is not clear which enhancers among the tens of thousands that have been recently identified function to drive stimulus-responsive transcription. In the nervous system, the chromatin state of terminally differentiated neurons not only maintains neuronal identity but also provides a platform for sensory experience-dependent gene expression, which plays a critical role in the development and refinement of neural circuits and in long-lasting changes in neuronal function that underlie learning, memory, and behavior. Using chromatin-immunoprecipitation followed by high through put sequencing (ChIP-Seq), we determined the effects of neuronal stimuli on the active chromatin landscape of mouse cortical neurons. We discover that stimulation with neuronal activity and brain derived neurotrophic factor (BDNF) cause rapid, widespread, and distinct changes in the acetylation of histone H3 lysine 27 (H3K27Ac) at thousands of enhancers throughout the neuronal genome. We find that functional stimulus-responsive enhancers can be identified by stimulus- inducible H3K27Ac, and we use this dynamic chromatin signature to discover neuronal enhancers that respond to neuronal activity, BDNF, or both stimuli. Finally, we investigate the transcriptional mechanisms underlying the function of stimulus responsive enhancers. We show that a subset of stimulus-responsive enhancers in the nervous system require the coordinated action of the stimulus-general transcription factor activator protein 1 (AP1) with additional stimulus-specific factors. Our studies reveal the genome-wide basis for transcriptional specificity in response to distinct neuronal stimuli. Furthermore, the comprehensive identification of neuronal activity and BDNF-dependent enhancers in cortical neurons provides a critical resource for elucidating the role of stimulus-responsive transcription in synaptic plasticity, learning and memory, behavior, and disease. Finally, the epigenetic signature of stimulus-inducible H3K27Ac may aid in the identification and study of stimulus- regulated enhancers in other tissues.

<p>Value at Risk (VaR) approach has been extensively used by investment and commercial banks since its development by JP Morgan in 1990s. As time passes, it has become interesting to investigate whether VaR could be used also by other financial intermediaries like pension funds and insurance companies. The aim of this paper is to outline Value at Risk (VaR) methodology by giving more emphasis on parametric approach which is used for empirical section and to investigate the applicability and usefulness of VaR in pension funds. After providing theoretical framework for VaR approach, the paper continues with pension fund systems in general and especially highlights AP funds of Swedish National pension fund system by trying to show why VaR could be an invaluable risk management tool for these funds together with other traditional risk measures used. Based on this given theoretical frame, a practical application of VaR –parametric or covariance/variance method- is executed on 50 biggest investments in the fixed income and equity portfolios of three selected Swedish national pension funds – AP1, AP2 and AP3. Results of one day VaR (DEAR) estimations on 30/12/2005 for each fund have been presented and it is aimed to show the additional information that could be obtained by using VaR and which is not always apparent from other risk measures employed by funds. According to the two traditional risk measures which are active risk and Sharpe ratio; AP2 and AP3 lie in the same risk level for 2005 which can create a contradiction by considering their different returns. On the other hand, obtained DEAR estimates show their different risk exposures even with the 50 biggest investments employed. The results give a matching relationship between return of funds and DEAR estimates meaning that; the fund with the highest return has the highest DEAR value and the fund with the lowest return has the lowest DEAR value; which is consistent with the main rule- “higher risk, higher return”. Thus, we can conclude that VaR could be applied additionally to get a better picture about real risk exposures and also to get valuable information on expected possible loss together with other traditional risk measures used.</p><p>Key words: Value at Risk, DEAR, Pension funds, Risk management, Swedish pension plan, AP1, AP2, AP3</p>

The cJUN NH2-terminal kinase (JNK) pathway responds to environmental stresses and participates in many cellular processes, including cell death, survival, proliferation, migration, and genome maintenance. Importantly, genes that encode components of the JNK signaling pathway are frequently mutated in human breast cancer, but the functional consequence of these mutations in mammary carcinogenesis is unclear. Anoikis – suspension-induced apoptosis – has been implicated in oncogenic transformation and tumor cell metastasis. Anoikis also contributes to lumen formation during mammary gland development and epithelial cell clearance during post-lactational involution. JNK is known to contribute to certain forms of cell death, but the role of JNK during anoikis was unclear. I examined the requirement of JNK in anoikis and discovered that JNK promotes cell death by transcriptional and post-translational regulation of pro-apoptotic BH3-only proteins. This conclusion suggested that JNK signaling may contribute to mammary gland remodeling during involution. Indeed, JNK deficiency in mammary epithelial cells disrupted the remodeling program of gene expression and delayed involution. Finally, I sought to understand the importance of JNK in mammary carcinogenesis. I found that JNK loss in the mammary epithelium was sufficient for genomic instability and tumor formation. Moreover, JNK loss in a model of breast cancer resulted in significantly accelerated tumor development. Collectively, these studies advance our understanding of the JNK pathway and breast biology, and provide insight that informs the design of therapeutic approaches that target the JNK signal transduction pathway.

In dieser Dissertation wurde eine isolierte Brachydaktylie vom Typ E (BDE) untersucht. Grundlage war eine Familie mit autosomal-dominanten Erbgang BDE. Der genetische Hintergrund ist eine balancierte Translokation t(8;12)(q13;p11.2). Der Bruchpunkt auf derivativem Chromosom der(8) liegt 86 kb strangaufwärts des chondrogenetisch essentiellen Kandidatengens PTHLH (Parathyroid hormone like hormone). PTHLH ist für die Differenzierungsrate von proliferativen Chondrozyten verantwortlich. Positiv oder negativ reguliertes Pthlh führen zu einer Dysbalance mit Brachydaktylie-ähnlichen Phänotypen in murinen Tiermodellen. Der Leserahmen des Kaliumkanals KCNB2 auf Chromosom 8 wurde durch die Translokation in Intron 2 getrennt. Chrondrogenetische KCNB2 Funktionen konnten durch in situ Hybridisierungen ausgeschlossen werden. Der Translokationsbruchpunkt auf der(8) liegt in einer in Mammalia hochkonservierten Region und beeinhaltet ein Bindungsmotiv für AP1 Transkriptionsfaktoren. Durch die Translokation befindet sich in unmittelbarer Nähe eine Kernkonsensussequenz für ETS Transkriptionsfaktoren. AP1 und ETS Transkriptionsfaktoren interagieren und wurden auf eine potentielle PTHLH Regulation untersucht. Epigenetische Histonmodifizierungen, charakteristisch für cis-regulatorische Elemente, sowie Reportergenassays mit AP1 und ETS1 Bindungsmotiven zeigten einen Bezug zur PTHLH Regulation. Bindungsassays mit AP1 und ETS1 Transkriptionsfaktoren an den Bruchpunktsequenzen, sowie funktionelle in vitro Experimente mit Chondrozyten verifizierten die Hypothese, dass der Translokationsbruchpunkt strangaufwärts von PTHLH regulatorische Eigenschaften besitzt. Die AP1 und ETS1 Transkriptionsfaktoren regulierten PTHLH positiv in ATDC5 und C28/I2 Chondrozyten. In chondrogeninduzierten Patientenfibroblasten war die PTHLH Expression inhibiert. Die molekulare Pathogenese der BDE wurde durch die bisher unbekannte chondrogene PTHLH Fehlregulation dargestellt. / We studied a 3-generation family with Brachydactyly Type E (BDE) and identified a t(8;12)(q13;p11.2) translocation. We identified PTHLH (Parathyroid hormone like hormone) on chromosome 12p11.2 and the ionchannel KCNB2 on chromosome 8q13 as candidate genes. KCNB2 was disrupted in intron 2, while the chromosome 12 breakpoint is localized 86 kb upstream of PTHLH; only the latter gene is involved in chondrogenesis. The 12p11.2 breakpoint is conserved and features an AP1 binding site 86 kb upstream of PTHLH. Due to the translocation, an ETS binding site from 8q13 resided near the AP1 site. Since both transcription factors interact, we tested if AP1 and ETS1 can activate PTHLH in ATDC5 and C28/I2 chondrocytes. We used the breakpoint sequences of the derivative chromosomes 8 and 12 and the nonaffected chromosome 8 and 12 allele sequences in reporter-gene assays. Reporter-gene constructs containing the der(8) breakpoint revealed activation in murine and human chondrocytes. The enrichment of histone modifications, implicating cis-regulatory effects were investigated in the breakpoint area. We found the enriched histone H3K4me1 modification at the chromosome 12 breakpoint position in murine and human chondrocytes, while affected fibroblasts showed higher H3K4me1 enrichment at the der(8) breakpoint compared to wt(12) allele. Furthermore, the breakpoint sequence bound to AP1 and C-ets-1 in EMSA. Western blotting after PMA-stimulated AP1 and ETS1 activation and overexpression of different AP1 and ETS1 combinations showed activated PTHrP expression in chondrocytes. In chondrogenic induced BDE fibroblasts PTHLH was inhibited, while IHH was upregulated. We suggest that PTHLH was dysregulated by the translocation in BDE chondrocytes. This could lead to BDE. We highlight the impact to characterize genomic breakpoints in detail and demonstrate a novel AP1- and ETS1-directed chondrogenic PTHLH regulation in wild-type chondrocytes and dysregulation in the pathogenesis of BDE.