Dissertations / Theses on the topic 'Suppression history'

We apply a combination of suppression and release criteria to reconstruct the disturbance history of a ponderosa pine – Douglas-fir stand in central Idaho. In this stand, disturbance, likely fire, induced growth releases in some trees, and sudden, severe suppressions in others. To characterize growth release following disturbance, we developed boundary-line release criteria for Douglas-fir and ponderosa pine. Suppression criteria were applied to identify disturbances defined as a growth reduction of more than 1.8 standard deviations sustained for a minimum of five years. To prevent confusing a true release event with growth increases associated with recovery from suppression, release events were not tallied for at least fifteen years following a suppression event. Release and suppression events were combined to create a disturbance chronology characterized by a high frequency of disturbance between 1820 and 1920. This period of disturbance likely reflects post-European settlement land uses such as grazing and logging as well as an increase in fire frequency. Fire suppression in the latter part of the 20th Century likely explains the decrease in disturbance after 1940. We believe that a combination of release as well as suppression criteria best describes the disturbance history of this stand.

Thesis (MMil)--Stellenbosch University, 2006.
ENGLISH ABSTRACT: The use of military force to suppress internal unrest has been an integral part of South African history. The European colonisation of South Africa from 1652 was facilitated by the use of force. Boer commandos and British military regiments and volunteer units enforced the peace in outlying areas and fought against the indigenous population as did other colonial powers such as France in North Africa and Germany in German South West Africa, to name but a few. The period 1912 to 1945 is no exception, but with the difference that military force was used to suppress uprisings of white citizens as well. White industrial workers experienced this military suppression in 1907, 1913, 1914 and 1922 when they went on strike. Job insecurity and wages were the main causes of the strikes and militant actions from the strikers forced the government to use military force when the police failed to maintain law and order. Public reaction to the use of force was strong and the government, particularly Gen. J.C. Smuts, was severely criticised resulting in a defeat in the 1924 election. Over the period 1921 to 1932 indigenous populations in South Africa and South West Africa such as the Israelites (1921), the Bondelswarts (1922), the Rehoboth Basters (1925) and the Ukuambi (1932), were suppressed through punitive expeditions by the police and military forces of the Union of South Africa. The indigenous populations were a.o. grieved by the government’s implementation of branding laws, enforced indentured labour, dog and hut tax. The government’s prevailing racial policy of that time, manifested in a master and servant attitude towards the indigenous populations, exacerbated an existing grievance of restrictive political rights. The government reacted quickly and economically in suppressing any indigenous population’s protests involving militant action. Although the use of aeroplanes was criticised, it was a force multiplier and greatly assisted the small number of police and military forces deployed in minimising casualties on both sides. The government also had to suppress militant Afrikaner uprisings during the First and Second World Wars. In 1914 and 1915, prominent Afrikaner leaders and veterans of the Anglo-Boer War reacted militantly against the government’s participation in the First World War. Gen. L. Botha and Gen. Smuts were the architects of their suppression through quick mobilisation of the Active Citizen Force, using mostly Afrikaans speaking volunteers. The period between the two world wars saw the growth of the Afrikaners on a political, social and limited economical level. This gave rise to further dispute on political and social levels when the government once again opted to fight alongside Britain in the Second World War. Old animosities between the Afrikaners and British were relived and militant elements within Afrikaner society mobilised to impede this participation. The government resorted to using the Union Defence Forces and SA Police to facilitate internment, for spying and to guard strategic objectives in an effort to prevent sabotage and other serious damage to the war effort. Smuts received severe criticism from mostly Afrikaners who were against participation in the war, and the general public who had to suffer under the conditions of martial law.
AFRIKAANSE OPSOMMING: Die gebruik van militêre mag in die onderdrukking van interne onrus is ‘n algemene verskynsel in die geskiedenis van Suid-Afrika. Sedert 1652 het die Europese koloniale besetting van Suid-Afrika gepaard gegaan met geweld. Boerekommando’s en Britse militêre regimente en vrywilligereenhede het die vrede in verafgeleë gebiede gehandhaaf en die plaaslike bevolkings onderwerp, net soos ander koloniale moondhede, byvoorbeeld, Frankryk in Noord-Afrika en Duitsland in Duits-Suidwes-Afrika gedoen het. Die periode van 1912 tot 1945 was geen uitsondering nie, maar met die verskil dat opstande ook onder die blanke bevolking onderdruk is. In 1907, 1913, 1914 en 1922 het die blanke industriële werkers sodanige onderdrukking ervaar. Werksonsekerheid en loongeskille was die dryfkrag agter die stakings en die stakers se militante optrede het die regering gedwing om militêre mag te gebruik om die opstande te onderdruk, nadat die polisie se pogings om wet en orde te handhaaf, misluk het. Die publiek was sterk gekant teen sulke hardhandige optrede en Genl. J.C. Smuts het veral onder kritiek deurgeloop, wat tot sy politieke nederlaag gelei het. Opstandige inheemse bevolkings in Suid-Afrika en Suidwes-Afrika soos die Israeliete (1921), die Bondelswarts (1922), die Rehoboth Basters (1925) en die Ukuambi (1932) het deurgeloop onder strafekspidisies van elemente van die Unie van Suid-Afrika se polisie en weermag. Die inheemse bevolking is gegrief deur die regering se implimentering van brandmerkwette, geforseerde kontrakarbeid, hut- en hondebelasting. Die regering se rassebeleid van die tyd het ‘n meester-en-onderdaan-houding teenoor die inheemse bevolkings geskep, wat die teer kwessie van beperkte politieke regte vererger het. Opstande deur inheemse bevolkings wat militant van aard was, is op ‘n vinnige en ekonomiese manier onderdruk, dog het skerp kritiek uitgelok. Die benutting van vliegtuie om die opstande te onderdruk was ‘n magsvermenigvuldiger wat die klein polisie- en weermag gehelp het om verliese tydens die onderdukking van opstande aan beide kante te beperk. Die regering het ook opstande van Afrikanergroepe tydens die Eerste en Tweede Wêreldoorlog onderdruk. In 1914-1915 het prominente Afrikanerleiers en veterane van die Anglo-Boereoorlog militant opgeruk teen die regering in verset oor die regering se deelname aan die Eerste Wêreldoorlog. Genl. L. Botha en Genl. Smuts was die argitekte van die vinnige onderdrukking van die opstande deur die Aktiewe Burgermag op te roep en hoofsaaklik Afrikaanssprekende vrywilligers te gebruik. Die periode tussen die twee Wêreldoorloë is gekenmerk deur die groei van die Afrikaner op politieke, sosiale en in ‘n beperkte mate, ook ekonomiese gebied. Hieruit het verdere onenigheid op politieke en sosiale vlak onstaan toe die regering weer besluit het aand die kant van Brittanje tot die Tweede Wêreldoorlog toe te tree. Ou vyandighede tussen Afrikaans- en Engelssprekendes het herleef en militante elemente binne die Afrikanersamelewing het gemobiliseer om die deelname te belemmer. Die regering het die Unieverdedigingsmag en die SA Polisie gebruik vir internering, spioenering en die beveiliging van strategiese doelwitte teen sabotasie en ander aktiwiteite wat die oorlogsdeelname sou belemmer. Smuts het die meeste kritiek ontvang van Afrikaners wat gekant was teen die oorlog, asook die publiek in die algemeen wat gebuk gegaan het onder krygswet.

This thesis examines the Royal Navy’s efforts to suppress the transatlantic slave trade between 1807 and the mid-1860s. The role of the West Africa squadron in detaining slave ships embarking from the West African coast was instrumental in the transformation of Britain’s profile from a prolific slave trading nation to the principal emancipator of enslaved Africans. The wider framework for naval suppression encompassed international law, official policy and diplomacy, but at the operational frontline of the campaign were naval personnel. This history of suppression shifts the emphasis from political and diplomatic contexts to the experiences of naval officers tasked with the delivery of the anti-slavery message, positioning them at the heart of Britain’s abolitionist campaign on the West African coast. Through officers’ narratives and personal testimonies – found in letters, journals, report books and diaries – it examines the reactions, relations and encounters of these agents of change, and their contributions to the exchange of information crucial to Britain’s anti-slavery efforts in West Africa. The personal, social and cultural experiences of naval officers provide insight into attitudes towards the key themes of Britain’s abolitionist mission, namely anti-slavery beliefs, burgeoning empire, and national identity. In their responsibilities to confront the human trauma of the slave trade and liberate enslaved Africans, officers engaged with humanitarian ideals and anti-slavery rhetoric. These ideas had significant impact on how they conceived their identity as Britons and the nature of their duty as naval personnel, but could be undermined by their disgust at the conditions of service on the West African coast. Officers were also at the forefront of Britain’s broader anti-slavery assault on shore, intended to reform West African society to European, ‘civilised’ standards. In their encounters with slavery and African peoples, officers faced numerous concerns, including concepts of racial identity, paternalism and the true meanings of freedom.

The main purpose of this research is to re-examine Chartism by analysing how the Home Office’s suppression of the movement affected the development of the British State and the machinery of public order during the 1830s and 1840s. In recent years, the study of Chartism has become a domain for historians engaged in cultural history. As a result, studies of both a political and localised nature have been neglected. The poverty of recent research in these areas has occurred since the major dispute between Dorothy Thompson and Gareth Stedman Jones, over the ‘linguistic’ turn and the meaning of the language of Chartism took place during the 1980s. Since the early-1990s, the debate has now moved on towards what Patrick Joyce and James Vernon have identified as ‘the language of politics’. The aim of this research is to move the debate away from a cultural perspective and, instead, to examine how government policy changed to deal with Chartism. The purpose of this study is, therefore, not to examine the legislative effects of social, political and economic reforms as suggested by Gareth Stedman Jones, but to offer a more thorough investigation of the lines of argument pursued by Dorothy Thompson and James Vernon. Thompson argued that state suppression played a huge role in the demise of Chartism, whilst Vernon has asserted that during the first half of the nineteenth century the political system gradually became closed and disciplined. Mass movements such as Chartism, it is argued, failed in their quest to bring about major changes to the political system in the early nineteenth century, largely because they succumbed to huge pressure from the state and its institutions. In order to establish the influence of the Home Office, this study has analysed how its policy impacted upon the Chartists in the West Riding. This involved a struggle for hegemony between central government and local agencies which ultimately brought about significant changes to the way in which the state functioned, along with many improvements to its machinery of control. These reforms included the advent of better policing and a gradual redefining of the roles of traditional forms of control such as the magistracy, army, militia and yeomanry. From a thorough investigation of both primary and secondary source materials, the evidence suggests that Dorothy Thompson was generally correct in her observation that the Home Office suppression of Chartism allowed the state to learn from its mistakes and become more effective in managing public order. However, this study will argue that the process was not as clear cut as Thompson implied. The implementation of reforms was a gradual process in which the Home Office played a significant role in the management of tensions that existed amongst various central and local government agencies. In doing so, the state became more efficient in controlling disorder. It remains for others to investigate the view of Gareth Stedman Jones that Chartism was by-passed by a reforming state.

Doctor of Philosophy
Department of History
Donald J. Mrozek
During the Cold War, the United States’ foreign policy relied heavily on its ability to project military power. More often than not, the central component of force projection rested on the United States military’s effectiveness in employing air power both by establishing air superiority and through accurate delivery of ordnance. As the primary service tasked with conducting aerial warfare, the United States Air Force (USAF) was expected to maintain this capability either to achieve deterrence or, when necessary, to military action. In January 1973, the USAF seemed incapable of performing the latter task due to the North Vietnamese Integrated Air Defense System’s (NV-IAD’s) effectiveness in Operation Rolling Thunder and its successor, Operation Linebacker. Eighteen years later, Air Force aircraft spearheaded the Coalition’s air attack on the Iraqi Integrated Air Defense System (I-IADS) in January 1991. Considered by many to be the most effective air defense system outside the Soviet Union’s, the I-IADS was expected to exact heavy casualties from the allied forces. Instead, in less than twenty days, the USAF’s dominance was so complete that politicians, analysts and military historians quickly proclaimed a “Revolution in Military Affairs” (RMA). The majority of the current historiography credits advances in precision-guided munitions (PGMs), airframes, and computer technology as the impetus for the RMA. Others have claimed that the USAF’s training methodology and construction of advanced training sites such as the Red Flag complex at Nellis Air Force Base were the primary drivers for the Air Force’s success. While acknowledging the role all of these factors played, this dissertation also demonstrates the key role played by the development of Suppression of Enemy Air Defense (SEAD) doctrine from January 1973 through August 1991. In the aftermath of the American war in Vietnam, the Air Force considered defense suppression a tactical task that was secondary to the primary mission of putting ordnance on target. At the end of Desert Storm, proponents of the Air Force’s SEAD doctrine had convincing evidence that an enemy IADS was not just an ancillary weapons array, but functioned a critical national system just like manufacturing, government, or the people’s will. The process by which this viewpoint changed had effects on the development of the United States Air Force’s Cold War conventional capability in general, and the development of training methods, electronic warfare platforms, and modern airframes specifically.

The European Witch-Hunts reached their peak in the sixteenth and seventeenth centuries. Betweeen 1590 and 1661, approximately 1500 women and men were accused of, and executed for, the crime of witchcraft in Scotland. England suffered the largest witch-hunt in its history during the Civil Wars of the 1640s, which produced the majority of the 500 women and men executed in England for witchcraft. Evidence indicates, however, that only three women were executed in Ireland between 1533 and 1670. Given the presence of both English and Scottish settlers in Ireland during the sixteenth and seventeenth centuries, the dramatic discrepancy of these statistics indicate that conditions existed in early modern Ireland that tended to suppress the mechanisms that produced witchcraft accusations and larger scale witch-hunts. In broad terms those conditions in Ireland were the persistence of Gaelic culture and the ongoing conditions of open, inter-religious conflict. In particular, two artifacts of Gaelic Irish culture had distinct impact upon Irish witchcraft beliefs. The office of the Poet, or fili (singular for filid), seems to have had a similar impact upon Gaelic culture and society as the shaman has on Siberian witchcraft beliefs. The Gaelic/Celtic Poet was believed to have magical powers, which were actually regulated by the Brehon Law codes of Ireland. The codification of the Poet’s harmful magic seems to have eliminated some of the mystique and menace of magic within Gaelic culture. Additionally, the persistent belief in fairies as the source of harmful magic remained untainted by Christianity throughout most of Ireland. Faeries were never successfully demonized in Ireland as they were in Scotland. The Gaelic Irish attributed to fairies most of the misfortunes that were otherwise blamed on witchcraft, including the sudden wasting away and death of children. Faerie faith in Ireland has, in fact, endured into the twentieth century. The ongoing ethno-religious conflict between the Gaelic, Catholic Irish and the Protestant “New English” settlers also undermined the need for witches in Ireland. The enemy, or “other” was always readily identifiable as a member of the opposing religious or ethnic group. The process of dual confessionalisation, as described by Ute Lotz-Huemann, facilitated the entrenchment of Catholic resistence to encroaching Protestantism that both perpetuated the ethno-religious conflict and prevented the penetration of Protestant ideology into Gaelic culture. This second effect is one of the reasons why fairies were never successfully associated with demons in Ireland. Witch-hunts were complex events that were produced and influenced by multiple causative factors. The same is true of those factors that suppressed witchcraft accusations. Enduring Gaelic cultural artifacts and open ethno-religious conflict were not the only factors that suppressed witchcraft accusations and witch-hunts in Ireland; they were, however, the primary factors.

In 2009, the Archdiocese of New Orleans went through a reorganization that resulted in the closure of numerous parishes under its direction. This thesis will look at how one of the parishes closed during this reorganization, St. Henry’s, had already faced, and survived, numerous attempts at closure. A study of these previous attempts reveals that internal church politics were often on display and the driving force behind the decisions. Using documents from the Archdiocesan Archives of New Orleans, this thesis looks at the history and leadership of St. Henry’s parish, and examines how the survival of a church often has more to do with the personalities of those in leadership positions and less to do with the propagation of faith.

Thesis (Ph. D.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed March 23, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 234-247).

Le gène suppresseur de tumeur LKB1 code une protéine sérine/thréonine kinase qui régule le métabolisme et la polarité cellulaires. LKB1 exerce une partie de ses fonctions biologiques en phosphorylant et en activant les 14 kinases appartenant à la famille des protéines kinases activées par l'AMP (AMPK). Le membre éponyme de cette famille, AMPK, agit comme un senseur nutritionnel essentiel dans la cellule. La recherche que j'ai conduite au cours de ma thèse a porté sur le mode de régulation de LKB1. L'holoenzyme LKB1, un hétérotrimère comprenant deux autres protéines appelées STRAD et MO25, est dotée d'une activité catalytique constitutive. Mon travail a permis de montrer que la lysine 48 de LKB1 est acétylée par l´acétyltransférase GCN5. Par des approches biochimiques et des techniques d'imagerie, j'ai montré que l'acétylation de LKB1 par GCN5 favorise sa localisation nucléaire, la fraction non-acétylée étant localisée à la fois dans le cytoplasme et le noyau. GCN5 promeut également l´export cytoplasmique de LKB1 de manière HAT-indépendente et régule son niveau d´expression. Afin de préciser la contribution de cette acétylation à la fonction in vivo de LKB1, j'ai utilisé le modèle expérimental de la crête neurale (CN) chez le poulet. En effet, j'ai été impliquée au cours de ma thèse dans une étude issue du laboratoire, qui a établi que l'activité de LKB1 est requise pour la délamination, la migration polarisée et la survie des cellules de la CN céphalique. Ces dernières contribuent à la formation de la majorité du squelette cranio-facial des vertébrés. Le signal LKB1 dans ces cellules est relayé par l'AMPK et la kinase ROCK et converge sur le moteur moléculaire dépendant de l'actine, la Myosine II. A l'aide du même modèle expérimental, j'ai montré que GCN5 est exprimé dans les cellules de la CN au cours de l'embryogenèse et que l'interaction fonctionnelle entre LKB1 et GCN5 est nécessaire à l'activité de LKB1 au cours de l'ontogénie des cellules de la CN céphalique et donc de la formation de la tête
The tumor suppressor gene LKB1 encodes a serine/threonine kinase which regulates the cellular metabolism and polarity. Its biological activity is partly exerted through the phosphorylation and activation of 14 kinases which belong to the AMP-activated protein kinases (AMPK). The eponym member of this family acts as an essential nutritional sensor in the cell. The research that I conducted during my PhD focused on the regulation of LKB1. The LKB1 holoenzyme is a constitutively active heterotrimer comprising two other proteins called STRAD and MO25. My PhD project shows that LKB1 is acetylated on the lysine 48 residue by the acetyltransferase GCN5. Using biochemical approaches and cell imaging, I have shown that the acetylation of LKB1 by GCN5 favors its nuclear localization, while the non-acetylated fraction is localized in both the nucleus and the cytoplasm. GCN5 also promotes the cytoplasmic export of LKB1 in an HAT-independent manner and regulates its expression levels. In order to investigate the contribution of this acetylation to the functions of LKB1 in vivo, I have used the experimental model of the neural crest (NC) in chick embryos. Indeed, during my PhD, I have contributed to a study, initiated by my host laboratory, in which we show that LKB1 is required for the delamination, polarized migration and survival of neural crest cells (NCCs) which contribute to the formation of most craniofacial structures in vertebrates. LKB1 signaling is mediated by AMPK and the ROCK kinase and converges towards the actin-dependent molecular motor, Myosin II. Using the same experimental model, I have shown that GCN5 is expressed in NCCs during embryogenesis and that the functional interaction between GCN5 and LKB1 is essential for the activity of LKB1 in the cephalic NCCs ontogenesis and head formation

The NAD-dependent deacetylase SIRT1 regulates several factors involved in stress response and cell survival but its function in cancer is largely unknown. Research suggests that SIRT1 influences several transcription factors and molecules that are important components of pathways often deregulated in cancer. Our experiments have shown that SIRT1 knock down by short hairpin RNA accelerates tumor xenograft formation by HCT116 colon cancer cells, whereas SIRT1 overexpression inhibits tumor formation. We have also found that, pharmacological inhibition of SIRT1 stimulates cell proliferation under conditions of growth factor deprivation suggesting a tumor suppressive function of SIRT1. Paradoxically, SIRT1 inhibition sensitizes the same cells to apoptosis by chemotherapeutic drugs. Immunohistochemical staining of a colon tumor microarray revealed high SIRT1 expression levels in normal colon mucosa and benign adenomas. SIRT1 overexpression was observed in nearly 25% of stage I/II/III colorectal adenocarcinomas but rarely found in advanced stage IV tumors. Furthermore, about 30% of carcinomas showed lower than normal SIRT1 expression. These results suggest a pleiotropic effect of SIRT1 in cancer, i.e., anti-proliferative as well as anti-apoptotic. Further experiments along these lines and examination of a larger patient cohort could provide a rationale for the use of SIRT1 activators and inhibitors in the prevention and treatment of cancer.

BACKGROUND: Prostate cancer (PCa) is the most commonly diagnosed solid tumor and the second leading cancer death in the United States, and also one of the major cancer-related deaths in Chinese. Androgen deprivation therapy (ADT) is the first line treatment for metastatic PCa. PCa ultimately relapses with subsequent ADT treatment failure and becomes castrate-resistant (CR). It is important to develop effective therapies with a surrogate marker towards CR PCa. METHOD: Histone deacetylase (HDAC) inhibitors were examined to determine their effects in androgen receptor (AR)/ cellular prostatic acid phosphatase (cPAcP)-positive PCa cells, including LNCaP C-33, C-81, C4-2 and C4-2B and MDA PCa2b androgen-sensitive and androgen-independent cells, and AR/cPAcP-negative PCa cells, including PC-3 and DU 145 cells. Cell growth was determined by cell number counting. Western blot analyses were carried out to determine AR, cPAcP and PSA protein levels. RESULTS: cPAcP protein level was increased by HDAC inhibitor treatment. Valproic acid, a HDAC inhibitor, suppressed the growth of AR/cPAcP-positive PCa cells by over 50% in steroid-reduced conditions, higher than on AR/cPAcP-negative PCa cells. Further, HDAC inhibitor pretreatments increased androgen responsiveness as demonstrated by PSA protein level quantitation. CONCLUSION: Our results clearly demonstrate that HDAC inhibitors can induce cPAcP protein level, increase androgen responsiveness, and exhibit higher inhibitory activities on AR/cPAcP-positive PCa cells than on AR/cPAcP-negative PCa cells. Upon HDAC inhibitor pretreatment, PSA level was greatly elevated by androgens. This data indicates the potential clinical importance of cPAcP serving as a useful biomarker in the identification of PCa patient sub-population suitable for HDAC inhibitor treatment.

During hematopoiesis, multilineage progenitor cells and the precursors are committed to individual hematopoietic lineages. In normal myelopoiesis, the immature myeloid cells (IMCs) differentiate into macrophages, neutrophils or dendritic cells. However, under tumor burden, these IMCs differentiate into myeloid derived suppressor cells (MDSCs) result in an up-regulation of immune suppressive factors and pro-tumor effect. The development of normal or malignant is tightly controlled by endogenous signals such as transcription factors and epigenetic regulations. HDAC11 is the newest identified members of the histone deacetylase (HDAC) family. Previous study in our group had identified HDAC11 as a negative regulator of interleukin 10 (IL-10) production in antigen-presenting cells (APCs). However, the mechanisms of HDAC11 in regulating myeloid cells differentiation and function remained unclear. We have uncovered for the first time that in the absence of HDAC11, upon LPS stimulation, neutrophils isolated form mice displays an over-production of pro-inflammatory cytokines such as TNF-alpha and IL-6. Strikingly, these HDAC11KO neutrophils showed a significantly higher migratory and phagocytosis activity, resulting from an overexpression of the migratory receptor and cytokine CXCR/L2. We have performed Chromatin Immunoprecipitation (ChIP) analysis on the neutrophils and discovered that HDAC11 was recruited to the promoter regulatory region of these genes we have identified. This part of data will be discussed mainly in chapter 2. Not only does HDAC11 plays a crucial role in the neutrophil function, our group have also found out that lacking of HDAC11 result in an increased suppressive activity of the Myeloid-derived Suppressor Cells (MDSCs). The previous publication of our group had shown that the tumor bearing mice experienced a much more aggressive growth pattern in the HDAC11 KO mice compare with C57BL/6 wild type control. MDSCs isolated from mice lacking HDAC11 appeared to gain increased capability to suppress the function of antigen-specific CD8+ T cells in vitro. Followed by this initial study, in chapter 3, we observed an up-regulation of both expression and enzymatic activity of arginase 1 and Nos2, two enzymes that are crucial in regulating MDSCs suppressive function. The aberrant enzymatic activity of Arg1 and Nos2 in HDAC11KO MDSCs is possibly result from an over-expression of the lineage-specific transcription factor C/EBPβ, which is previously proved to be essential for the differentiation of functional MDSCs. Furthermore, our ChIP data confirmed that HDAC11 may play as an negative regulator of C/EBPβ. Recently, our lab had demonstrated that T cells lacking HDAC11 gained a hyperactive phenotype and anti-tumor effect, indicating that HDAC11 may play a dual role in the host immune system. We further performed an adoptive transfer therapy to C57BL/6 tumor bearing mice. Our data showed that the additional administration of HDAC11KO MDSCs could eliminate, at least partially, the anti-tumor effect by adoptive transfer of HDAC11KO T cells. Taken together, we have uncovered a previously unknown role for HDAC11 as a transcriptional regulator in the myeloid cells differentiation and function. Based on our data and previous work from our lab, we propose a dual role of HDAC11 played in the host immune system. In the absence of HDAC11, host defenders such as neutrophils and T cells are functionally more aggressive against intruders such as pathogen and cancer. However, the immune suppressors such as MDSCs became more suppressive. The contradictory role HDAC11 played in the immune system may provide some insights for the assessment of the pharmacological value of HDAC11 and contribute to the development of novel immunotherapeutic strategies.

La production des métabolites secondaires par les cultures de cellules indifférenciées est souvent limitée par la méconnaissance des voies métaboliques et de leur régulation. Dans le but d'étudier la relation entre l'accumulation de la S-adénosylméthionine (unique agent de méthylation dans les cellules) et la production des alcaloïdes nicotiniques du tabac, des protoplastes de tabac ont été transformés avec le gène sam-1 d'Arabidopsis thaliana. Des lignées transgéniques ont été obtenues et des plantes ont été régénérées à partir de certaines de ces lignées. L'analyse de l'activité SAM-s de ces lignées a permis de mettre en évidence qu'un certain nombre de transformant présente le phénomène de silence des gènes. L'analyse du contenu alcaloïdique dans ces cals de tabac a permis de mettre en évidence d'importants changements en fonction de la quantité de SAM présente dans les cellules. Les plantes transgéniques de tabac présentent jusqu'à deux fois plus de nicotine et de nornicotine que les témoins. Ces résultats confirment la notion de plasticité du métabolisme des plantes décrite par plusieurs auteurs. Le clonage d'ADNc correspondant à la S-adénosylhomocystéine hydrolase et à des homologues d'histones déacétylases d'Arabidopsis thaliana est aussi présenté.

Le travail s'intéresse à la Compagnie de Jésus sur une période qui englobe son temps de suppression. La perspective microhistoirique déploie le questionnement sur un cas d'étude – le collège de Fribourg en Suisse– qui permet d'envisager les liens entre ancienne et nouvelle Compagnie
The work focuses on the Society of Jesus over a period that includes its time of suppression. The micro-history perspective deploys the questioning on a case study - the college of Fribourg in Switzerland - which makes it possible to consider the links between the old and the new Company

In vivo DNA is compacted tightly, via its association with histones and non-histone proteins, into higher-order chromatin structure. In this state, the DNA is refractory to the cellular factors that require access to DNA. The repressive nature of chromatin is alleviated in part by the action enzymes that modify chromatin structure. There are two major groups of chromatin modifying enzymes: those that post-translationally modify histones by the addition of small chemical moieties and those that utilize the energy derived from ATP hydrolysis to physically disrupt chromatin structure. The SWI/SNF enzyme belongs to this latter group. The SWI/SNF complex was identified originally in yeast. Several of its subunits are required for the expression of a subset of inducible genes. The ATPase activity is provided by the SWI2/SNF2 protein. In mammals, there are two biochemically separable SWI/SNF complexes that contain either BRG1 or BRM, both homologs of yeast SWI2/SNF2. The yeast and mammalian SWI/SNF complexes are able to disrupt the Dnase I digestion pattern of in vitro assembled mononucleosomes and arrays, as well as facilitate the accessibility of restriction nucleases and transcription factors. The mechanism by which SWI/SNF functions has yet to be elucidated. SNF5 is a component of the yeast SWI/SNF complex. It is required for sucrose fermentation and mating type switching. The mammalian homolog of Snf5 is SNF5/INI1. SNF5/INI1 was identified simultaneously by two groups as a protein that shares homology with Snf5 and via a yeast two hybrid assay as a protein that interacts with HIV integrase (INtegrase Interactor). INI1 is a component of all mammalian SWI/SNF complexes purified to date. In humans, mutations and/or deletions in INI1 are associated with a variety of cancers, including malignant rhabdoid tumors, choroid plexus carcinomas, medullablastomas, primitive neuralectodermal tumors, and some cases of leukemia. Furthermore, constitutional mutations within INI1in individuals presenting with these tumors support the role of INI1 as a tumor suppressor. In this thesis, we show that Ini1 also functions as a tumor suppressor in mice. Approximately 20% of mice heterozygous for Ini1 present with tumors. Most of these tumors are undifferentiated or poorly differentiated sarcomas with variable rhabdoid features. All tumors examined to date show loss of heterozygosity at the Ini1 locus. We also show that Ini1 is essential for embryonic development. Mice homozygous-null for Ini1die between days 4 and 5.5 post-fertilization due to an inability to adhere to their substratum, form trophectoderm, and expand their inner cell mass. We further characterize the function of Ini1 in tumor suppression by generating mice heterozygous for both Ini1 and either Rb or p53. While heterozygosity at the Ini1 locus appears to have no effect on the rate of tumorigenesis in Rb-heterozygous mice, many of the tumors arising in compound heterozygous mice present with an altered morphology. This finding suggests that Ini1 may contribute to tumor progression due to loss of Rb. In contrast, mice compound heterozygous for Ini1 and p53 show a marked reduction in the rate of tumorigenesis compared to p53-heterozygous mice. Furthermore, the tumor spectrum is altered in these compound heterozygous mice. These findings suggest that Ini1 may function normally to repress p53 activity. Lastly, we show that expression of the Ini1 tumor suppressor itself is regulated tightly. Tissues and cells heterozygous for Ini1 express roughly equivalent levels of Ini1 protein and mRNA as their wild-type counterparts. We further show that this compensation is mediated by an increase in the rate of transcription from the wild-type Ini1 allele. Moreover, when exogenous Ini1 is introduced into Ini1-heterozygous cells, expression from the Ini1 promoter is reduced. These data indicate that a compensatory mechanism exists to ensure that the steady-state levels of Ini1 are constant. In summary, research detailed in this thesis has contributed to our understanding of the regulation of Ini1 as well as the role this protein plays in mammalian development and tumor suppression.

Le suppresseur de tumeur DOK1 (downstream of tyrosine kinases1) est une protéine régulatrice de voies de signalisation impliquées dans des processus cellulaires tel que la prolifération, la migration et l'apoptose. Le rôle suppresseur de tumeur de DOK1 a été démontré dans des modèles animaux. Les souris knock-out pour DOK1 présentent une forte susceptibilité de développer des leucémies, des tumeurs malignes hématologiques, des adénocarcinomes pulmonaires, ainsi que des sarcomes histiocytaires agressifs. En outre, nous avons rapporté précédemment que le gène DOK1 peut être muté et son expression réprimée dans différentes tumeurs malignes humaines, telles que les lignées cellulaires de lymphome de Burkitt (BL) et la leucémie lymphoïde chronique (LLC). Cependant, les mécanismes de dérégulation de DOK1 restent inconnus, notamment dans les processus de carcinogenèse induite ou non par des oncovirus. Dans ce projet de thèse, nous avons d'abord caractérisé le promoteur de DOK1 et le rôle du facteur de transcription E2F1 comme le principal régulateur de l'expression de DOK1. Nous avons démontré pour la première fois la contribution de DOK1 dans la réponse cellulaire au stress par son rôle suppresseur de prolifération cellulaire et promoteur d'apoptose. Nous avons trouvé que l'expression du gène DOK1 est réprimée dans une variété de cancers humains, y compris le cancer de la tête et du cou, les lymphomes de Burkitt et les cancers du poumon. Cette répression est due à l'hyperméthylation aberrante de DOK1. Nous avons donc étudié les événements épigénétiques, qui sont souvent altérés dans les cancers, et leurs implications dans la répression de DOK1 dans les lignes cellulaire cancéreuses de la tête et du cou. Nous nous sommes par la suite intéressés aux mécanismes de dérégulation de DOK1 par le virus d'Epstein Barr dans le cadre de sa propriété oncogénique dans les lymphocytes B humains ainsi que dans les lignes cancéreuses du lymphome de Burkitt. Nos résultats apportent de nouvelles informations sur les mécanismes de régulation de l'expression de DOK1 dans la carcinogenèse induite ou non par des oncovirus, ce qui pourrait le définir comme un biomarqueur potentiel de cancer et comme une cible intéressante pour des thérapies épigénétiques
The newly identified tumor suppressor DOK1 (downstream of tyrosine kinases1) inhibits cell proliferation, negatively regulates MAP kinase activity, opposes leukemogenesis, and promotes cell spreading, motility, and apoptosis. DOK1 also plays a role in the regulation of immune cell activation, including B cells. The tumor suppressor role of DOK1 was demonstrated in animal models. DOK1 knockout mice show a high susceptibility to develop leukemia, hematological malignancies as well as lung adenocarcinomas and aggressive histiocytic sarcoma. In addition, we previously reported that the DOK1 gene can be mutated and its expression is down-regulated in human malignancies such as Burkitt’s lymphoma cell lines (BL) and chronic lymphocytic leukemia (CLL). However, very little is known about the mechanisms underlying DOK1 gene regulation and silencing in viral- and non viral-related tumorigenesis. In the present project, we first characterized the DOK1 promoter. We have shown the role of E2F1 transcription factor as the major regulator of DOK1 expression and how DOK1 plays a role in DNA stress response though opposing cell proliferation and promoting apoptosis. We demonstrated that DOK1 gene expression is repressed in a variety of human cancers, including head and neck, Burkitt’s lymphoma and lung cancers, as a result of aberrant hypermethylation. We investigated the link between the epigenetic events and DOK1 silencing in non viral head and neck cancer cell lines, and by Epstein Barr virus in relation to its oncogenic activity in human B cells and neoplasia such as Burkitt’s lymphoma. These data provide novel insights into the regulation of DOK1 in viral and non viral-related carcinogenesis, and could define it as a potential cancer biomarker and an attractive target for epigeneticbased therapy

The MBD2-NuRD co-repressor complex is an epigenetic regulator of the developmental silencing of embryonic and fetal β-type globin genes in adult erythroid cells as well as aberrant methylation-dependent silencing of tumor suppressor genes in neoplastic diseases. Biochemical characterization of the MBD2-NuRD complex in chicken erythroid cells identified RbAp46/48, HDAC1/2, MTA1/2/3, p66α/β, Mi2α/β and MBD2 to comprise this multi-protein complex. In the work presented in Chapter 2, we have pursued biophysical and molecular studies to describe a previously uncharacterized domain of human MBD2 (MBD2IDR). Biophysical analyses show that MBD2IDR is an intrinsically disordered region (IDR). Despite this inherent disorder, MBD2IDR increases the overall binding affinity of MBD2 for methylated DNA. MBD2IDR also recruits the histone deacetylase core components (RbAp48, HDAC2 and MTA2) of NuRD through a critical area of contact requiring two contiguous amino acid residues, Arg286 and Leu287. Mutation of these critical residues abrogates interaction of MBD2 with the histone deacetylase core and impairs the ability of MBD2 to repress the methylated tumor suppressor gene Prostasin in MDA-MB-435 breast cancer cells. These findings expand our knowledge of the multi-dimensional interactions of the MBD2-NuRD complex that govern its function. In Chapter 3, we have discussed a novel mechanism for MBD2-mediated silencing of the fetal γ-globin gene. Through microarray expression analyses in adult erythroid cells of MBD2-/- mice, we identified ZBTB32 and miR-210 as downstream targets of MBD2. Over-expression of ZBTB32 and miR-210 in adult erythroid cells causes increased expression of the silenced fetal γ-globin gene. Thus, our results indicate that MBD2 may regulate γ-globin gene expression indirectly though ZBTB32 and miR-210 in adult erythroid cells.

This dissertation examines social and political conflict over gambling policy in the United States and Brazil from 1960 to the present with a particular focus on New York City and Rio de Janeiro. The study accounts for the process by which illegal numbers gambling in New York and the jogo do bicho in Rio de Janeiro were determined to be the basis for widespread corruption and lawlessness. As policy makers proposed enhanced government lotteries as a solution for the problem of illegal gambling, numerous groups scrambled for position within shifting gambling frameworks. Tens of thousands of persons who had long worked in illegal numbers networks pressed for access to legal gambling jobs, corporate entities partnering with government lotteries pushed to secure monopoly concessions, while many citizens and religious groups opposed any and all forms of gambling legalization. As gambling workers, bettors, clergy, police officers, politicians and corporate lobbyists all struggled over how gambling would be conducted going forward, an intense debate unfolded in both Brazil and the United States with issues relating to police corruption, welfare, public safety, state sovereignty, personal liberty, and distribution of the tax burden all under examination. While there are many comparative elements of this study, it is ultimately transnational in that the narrative histories of gambling policy in Brazil and the United States eventually converge through the gambling technology corporation Gtech, which emerged as a powerhouse in the government lottery sectors of both nations. As the low stakes illegal gambling games of the numbers and the jogo do bicho are suppressed in favor of legal government lotteries, a vast new array of gambling habits are introduced to the gambling public in both Brazil and the United States. Of particular importance to this study is the growth of multimillion-dollar jackpot games offered by governments and their corporate partners. As players leave behind the old games with their reasonable odds and their modest payouts, they take up new games with astronomical odds and obscene jackpots. In the argument of this study, jackpot style gambling has brought the gambling habits of the poor and working classes into accord with contemporary patterns of wealth distribution.

This thesis examines the Schultz Fire as a case study to explain the complex history of fire suppression management in America’s forests, and to gain further understanding of how management practices have affected the increase in fire severity levels and how forests respond to such a disturbance. The thesis objectives were: (1) to analyze the causes of the fire severity of the Schultz Fire, especially: topography, fuels, or weather; (2); to examine the possible correlation between fire severity and tree density; (3) to investigate whether post-fire species richness was related to fire severity two years after the Schultz Fire; (4) to investigate whether post-fire plant species richness, plant cover, and tree regeneration was related to fire severity two years after the Schultz Fire; and (5) to interlink and convey how these factors relate to the history of fire management and policy and public perception. The history of fire related policy and management has significantly changed the dynamics of America's national parks and forests. Understanding the larger context of this history, both of national fire management and of the effects of language and perception on policy and public reaction, is part of understanding the Schultz Fire as a whole. Based on modeling, high winds combined with the presence of high surface fuel load were the main causes of the Schultz Fire's high fire severity levels. As fire severity increased there was a statistically significant increase in species richness. Severity level had little variation on percentage of cover by plants. No statistically significant relationship between tree density and fire severity levels was found. These findings underline the need for fuel treatments in southwest Ponderosa Pine forests, and effective cooperation between communities, managers, and ecologists. The Schultz Fire serves as an example in understanding the intricacies of how history affects the present and future of fire management. How fire has been managed and portrayed in the past has left an indelible mark on how fire is presently viewed. Without a clear understanding of the history of fire management and the role of fire in the ecology, future policies towards fire will be unable to account for and manage for the diversity of ecosystems and fires effects on those ecosystems across the United States.
Graduation date: 2013

The submitted work aims to clerify changes of the image of the site of pilgrimage called Křemešník in social memory during the dynamic 20th century. Author leans on her bachelor's thesis, which was focused on Křemešník in the first thirty years of the 20th century. Now she tried to describe rivalry of ecclesiastic and touristic segment in the first half of the 20th century, replaced by establishment of the communist dictatorship. The reports of the church secretaries helped to find out the attitude of ruling power to Křemešník, means of changing or deleting the memory of the site and the success rate of this effort. Attention was also paid to perception of Křemešník by ordinary people, compared with contemporary state using a questionnaire. Extant written sources were supplemented with memories of contemporary witnesses.

abstract: Cancer is a disease which can affect all animals across the tree of life. Certain species have undergone natural selection to reduce or prevent cancer. Mechanisms to block cancer may include, among others, a species possessing additional paralogues of tumor suppressor genes, or decreasing the number of oncogenes within their genome. To understand cancer prevention patterns across species, I developed a bioinformatic pipeline to identify copies of 545 known tumor suppressor genes and oncogenes across 63 species of mammals. I used phylogenetic regressions to test for associations between cancer gene copy numbers and a species’ life history. I found a significant association between cancer gene copies and species’ longevity quotient. Additional paralogues of tumor suppressor genes and oncogenes is not solely dependent on body size, but rather the balance between body size and longevity. Additionally, there is a significance association between life history traits and genes that are both germline and somatic tumor suppressor genes. The bioinformatic pipeline identified large tumor suppressor gene and oncogene copy numbers in the naked mole rat (Heterocephalus glaber), armadillo (Dasypus novemcinctus), and the two-fingered sloth (Choloepus hoffmanni). These results suggest that increased paralogues of tumor suppressor genes and oncogenes are these species’ modes of cancer resistance.
Dissertation/Thesis
Pipeline results for cancer genes
Phylogenetic regressions with correction tests
Pipeline results for housekeeping genes
Masters Thesis Biology 2019

碩士
長庚大學
生物醫學研究所
101
Obesity is known to cause many health problems. Obesity is characterized by increased volume of adipose tissue, resulting in imbalance of energy homeostasis, leading to metabolic diseases such as diabetes. Adipose tissue secretes adipokines that regulate energy balance. The secretion is abnormal in obesity, including elevated secretion of the proinflammatory cytokine TNFα. TNFα induces inflammation and lipolysis in adipose tissue, leading to elevated serum levels of free fatty acids (FFAs) ; both inflammation and elevated FFAs are linked to insulin resistance and diabetes. Diabetic drug thiazolidinedione (TZD) suppresses inflammation and reduces serum levels of FFAs, thereby improving insulin sensitivity and relieving the symptom of diabetes patients. TZD is the ligand of peroxisome proliferator-activated receptor γ (PPARγ), a transcriptional factor whose function can be regulated by cofactors including coactivators and corepressors. Previous studies in macrophages shown that corepressors and histone deacetylase (HDACs) modulate TZD action of suppressing proinflammatory gene expression. However, the role of HDACs in TZD-mediated suppression of TNFα-induced lipolysis in adipocytes has not been studied. We applied HDAC inhibitor (HDACI) trichostatin A (TSA) to test if HDACs are involved in TZD suppression of TNFα-induced lipolysis. As in literature, TZD suppressed TNFα-induced lipolysis. TSA treatment not only increased basal lipolysis, but also attenuated TZD suppression of TNFα-induced lipolysis. Since TSA inhibits both class I and class II HDACs, we applied class-specific HDACIs in the experiments. Surprisingly, treatments with class I or class II HDACI, or the combination of both HDACIs did not show the same effect as TSA, suggesting the effect of TSA may not through HDAC inhibition. Interestingly, TSA treatment reduced the expression of PPARγ, which may account for its attenuation of TZD-mediated suppression of TNFα-induced lipolysis. Moreover, modulation of the activity of extracellular signal-regulated kinases and the levels of perilipin, a lipid droplet protein, may be involved in TSA action on lipolysis. Further experiments will be required to elucidate the mechanism by which TSA treatment reduces the expression of PPARγ, and to clarify if HDACs are involved in TZD-mediated suppression of TNFα-induced lipolysis.

Array-CGH analysis of the gastric cancer cell lines suggested that TXNIP loci were intact, suggesting that allelic loss might not be the major mechanism responsible for the downregulation of TXNIP in these cells. Furthermore, our data suggested that promoter hypermethylation of TXNIP may not be an important epigenetic mechanism that regulate the silencing of this gene. Chromatin immunoprecipitation (ChIP) assay revealed that SAHA induced hyperacetylation of histone H3 and H4 at the 5' flanking region of TXNIP gene, suggesting SAHA could promote TXNIP gene transcription via modification of histones located at the promoter region. Our data revealed that the loss or reduced expression of TXNIP in gastric cancer cells is associated with epigenetic histone acetylation mechanism.
Gastric cancer is a common cancer especially in Asian countries and is associated with high morbidity and mortality. Epigenetic inactivation of tumor suppressor is a common mechanism involved in carcinogenesis of a variety of human cancers and recent evidence suggested that targeting epigenetic modifications may be an approach to combat cancer. Our group and others have demonstrated frequent promoter methylation of cancer related genes in gastric cancer. In this study, we aim to identify cancer associated genes regulated by another important epigenetic mechanism, namely histone acetylation.
In addition, we demonstrated that over-expression of TXNIP significantly reduced cell migration ability and inhibited cell invasiveness in gastric cancer cells. Furthermore, absence or reduced expression of TXNIP in gastric cancer was associated with diffuse-type gastric cancer, advanced stage disease and predicted a poor disease specific survival. The findings supported that TXNIP is a functional tumor suppressor gene and may be a potential biomarker in gastric cancer.
We analyzed 25 paired gastric cancer and non-cancer gastric mucosa and found that expression of TXNIP mRNA level was reduced in 84% of gastric cancer and was significantly downregulated as compared to the paired non-cancer gastric tissues (p=0.002). Expression of TXNIP protein by western blot was down-regulated in 3 out of 5 cases. Furthermore, by immunohistochemical staining of TXNIP in tissue array containing 150 cases of gastric cancer also showed frequent down-regulation of TXNIP expression and ∼26% with complete lack of TXNIP expression.
We first showed that suberoylanilide hydroxamic acid (SAHA), a well known histone deacetylase inhibitor, has anti-proliferative effect in a panel of gastric cancer cell lines (MKN1, MKN7, MKN28, MKN45, SNU1, SNU16, AGS, N87 and KatoIII cells). We compared gene expression profiles of SAHA treated vs control AGS cells to identify a set of genes that were differentially upregulated by SAHA treatment. Based on our microarray analysis in nine gastric cancer cell lines (MKN1, MKN7, MKN28, MKN45, SNU1, SNU16, AGS, N87 and KatoIII) and normal gastric tissues, a set of commonly downregulated genes in gastric cancer cells was elucidated. Analysis of these data sets with subsequent confirmation using real-time PCR analysis, genes that were downregulated in gastric cancer cells but upregulated upon SAHA treatment were identified. Among these selected genes, Thioredoxin Interacting Protein (also known as VDUP-1/TBP2/TXNIP ) was down-regulated in all cancer cell lines tested, and its protein expression was significantly induced by SAHA treatment in a numbers of gastric cancer cell lines including AGS, MKN1, MKN45, N87 and KatoIII. Thus, we focused on the TXNIP in the subsequent studies.
Tang, Angie.
Adviser: To Ka Fai.
Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references (leaves 180-202).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.

Xiao, Zhangang.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references (leaves 118-131).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts also in Chinese.

L’ubiquitination est une modification post-traductionnelle des protéines qui consiste à attacher, d’une manière covalente, le groupement ubiquitine sur un résidu lysine de la protéine cible. Cette modification peut avoir un impact considérable sur la fonction, la localisation et la stabilité de ces cibles. Une fois établie par des enzymes appelées E3 ligases, l’ubiquitination peut être enlevée par des enzymes spécifiques appelées déubiquitinases, modulant ainsi les effets causés par cette modification. BAP1 (BRCA1-Associated Protein 1) est une déubiquitinase de la famille des UCH (Ubiquitin C-terminal Hydrolases) qui a été initialement identifiée comme partenaire du suppresseur de tumeurs BRCA1 (BReast Cancer Associated gene 1). De nombreux groupes de recherche, incluant le nôtre, ont montré que BAP1 est associée avec d’autres cofacteurs formant un large complexe multiprotéique. Ce dernier est impliqué dans plusieurs processus cellulaires comme la transcription des gènes, la régulation de la chromatine, la coordination du cycle cellulaire et la réponse aux dommages à l’ADN. La cible majeure de BAP1 est l’histone H2A ubiquitinée sur la lysine 119, une marque d’histone qui a été souvent associée avec une conformation répressive de la chromatine. Quels sont les mécanismes régulant le complexe BAP1 lui permettant d’exécuter ces fonctions biologiques? Cela implique-t-il des modifications post-traductionnelles touchant les partenaires de BAP1 ? Ces questions restent encore sans réponse définitive. Ainsi, les objectifs de cette thèse sont de caractériser le mécanisme et la fonction du complexe BAP1 en étudiant les modifications post-traductionnelles de ses partenaires. Pour répondre à ces questions nous avons étudié les modifications post-traductionnelles touchant BAP1 et ses cofacteurs mutuellement exclusifs ASXL1 et ASXL2 (Additional Sex Comb-like 1,2). Nous avons démontré qu’ASXL1 et ASXL2 sont monoubiquitinés uniquement lorsqu’ils sont associés à BAP1. Sachant que les complexes BAP1/ASXLs sont conservés au cours de l’évolution, nous avons aussi démontré que la monoubiquitination des ASXLs est conservée chez la Drosophile. En utilisant des méthodes de déplétion de protéines par siARN et CRISPR/Cas9 ainsi que des mutants de perte de fonction de BAP1 et ASXL2, nous avons identifié les enzymes responsables de la monoubiquitination des ASXLs ainsi que leur effet sur l’activité catalytique de BAP1. D’autre part, nous avons étudié le développement chez la Drosophile ainsi que le cycle cellulaire des cellules humaines pour identifier la fonction biologique de la monoubiquitination de ASXL2. Nos résultats démontrent que la monoubiquitination d’ASXL2 sur la lysine 370 en présence de BAP1 est une modification post-traductionnelle conservée et catalysée directement par la famille UBE2Es des enzymes de conjugaison de l’ubiquitine (UBE2E1,2,3 chez les mammifères et UbcD2 chez la Drosophile). Cette monoubiquitination stimule l’activité catalytique de BAP1 chez les mammifères et de son orthologue Calypso chez la Drosophile envers H2Aub. Le blocage de la monoubiquitination des ASXLs par des mutations ciblant la lysine K370 induit une inhibition de l’activité de BAP1, ce qui cause une dérégulation du cycle cellulaire chez les cellules mammifères et une transformation homéotique haltère-aile chez la Drosophile. De plus, il nous a été possible de constater l’importance de cette monoubiquitination dans le cancer en démontrant la forte corrélation d’expression de BAP1/ASXL2 et les UBE2Es au niveau du mésotheliome, un cancer connu pour la dérégulation de BAP1. Nos résultats indiquent l’importance des modifications post-traductionnelles, dont la monoubiquitination, dans la régulation de la fonction et la stabilité du complexe BAP1. De plus, nous décrivons un nouveau mécanisme d’activation d’une deubiquitinase par la monoubiquitination de son cofacteur. D’autres études seront nécessaires afin de comprendre le lien entre l’activation de BAP1/ASXL2 par monoubiquitination et la fonction suppresseur de tumeurs de BAP1 via la deubiquitination d’H2Aub. D’autre part, nous avons fait l’observation que la déplétion de la deubiquitinase associée à la particule régulatrice du protéasome, PSMD14, induit non seulement une réduction drastique d’H2Aub dans la cellule, mais aussi une mort cellulaire rapide. Ceci nous a poussé initialement à investiguer l’implication de l’activité catalytique du protéasome dans la régulation d’H2Aub en lien avec la mort cellulaire. Malgré le fait que nous n’ayons pas trouvé un lien direct entre PSMD14 et la deubiquitination d’H2Aub, nous avons identifié plusieurs candidats (DUBs et E2s) impliqués dans l’induction de la mort cellulaire tout en surmontant une résistance acquise contre des inhibiteurs ciblant l’activité catalytique du protéasome. Ces candidats pourraient représenter des cibles intéressantes pour développer des inhibiteurs spécifiques afin de contrecarrer la résistance aux inhibiteurs du protéasome.
Ubiquitination is a post-translational modification of proteins that involves covalently attaching the ubiquitin moiety to the lysine residues of the target protein. This modification has been reported to have a significant impact on the function, localization and stability of these targets. Once established by enzymes called E3 ligases, ubiquitination can be removed by specific enzymes called deubiquitinases, thus modulating the effects caused by this modification. BAP1 (or BRCA1-Associated Protein1) is a deubiquitinase, from the UCH (Ubiquitin C-terminal Hydrolases) family, that was originally identified as a partner of the BRCA1 (BReast Cancer Associated gene 1) tumor suppressor. We and other research groups have shown that BAP1 is associated with other co-factors forming a multi-protein complex involved in several cellular processes such as gene transcription, chromatin regulation, cell cycle regulation and DNA damage response. The major target of BAP1 is ubiquitinated histone H2A, a histone mark that has been frequently associated with a repressive chromatin conformation. What are the mechanisms regulating the BAP1 complex allowing it to perform its biological functions? Does this involve post-translational modifications affecting BAP1 partners? These questions are still incompletely answered. Thus, the objectives of our studies are to characterize the mechanism and the function of the BAP1 complex by studying the post-translational modifications that could affect its obligate partners including ASXLs. To address these questions, we studied the post-translational modifications affecting BAP1 and its two mutually exclusive co-factors ASXL1 and ASXL2 (Additional Sex Comb-like 1,2). We demonstrated that ASXL1 and ASXL2 are mono-ubiquitinated only when associated with BAP1. Taking into account that the BAP1/ASXLs complexes are highly conserved during evolution, we also demonstrated that the mono-ubiquitination of ASXLs is important for Drosophila development. Using RNAi and CRISPR/Cas9 gene depletion methods and loss-of-function mutants of BAP1 and ASXL2, we identified the precise site of ASXLs ubiquitination, the enzymes responsible for establishing this mono-ubiquitination as well as its effect on catalytic activity of BAP1. On the other hand, we investigated Drosophila development as well as human cell cycle progression to identify the biological function of ASXLs mono-ubiquitination. Our results indicate that the mono-ubiquitination of ASXL2 on lysine 370 in the presence of BAP1 is a conserved post-translational modification catalyzed directly by the UBE2E family of ubiquitin-conjugating enzymes (UBE2E1, 2, 3 in mammals and UbcD2 in Drosophila). This mono-ubiquitination event stimulates the catalytic activity of BAP1 in mammals and its Drosophila ortholog Calypso towards H2Aub in vivo and in vitro. Blocking the mono-ubiquitination of ASXLs, by mutations targeting lysine K370, induces an inhibition of BAP1 catalytic activity causing a deregulation of human cell cycle progression and a haltere-to-wing homeotic transformation in Drosophila. In addition, we were able to assess the importance of ASXLs mono-ubiquitination in cancer using the mesothelioma tumor model, demonstrating a strong correlation between the expression of BAP1/ASXL2 and UBE2Es. Our results indicate the importance of post-translational modifications, including mono-ubiquitination, in the regulation of the function and stability of the BAP1 complex. Moreover, we describe a novel mechanism of activation of a deubiquitinase by the mono-ubiquitination of its co-factor. Further studies will be needed to shed more light on the link between BAP1/ASXLs activation by mono-ubiquitination and the tumor suppressor function of BAP1 via H2Aub deubiquitination. On the other hand, we have noticed that the depletion of PSMD14, a deubiquitinase associated with the proteasome regulatory particle, induces not only a drastic reduction of H2Aub in the cell, but also rapid cell death. This prompted us initially to investigate the involvement of the catalytic activity of the proteasome in the regulation of H2Aub in connection with cell death. Although we did not find a direct link between PSMD14 and H2Aub deubiquitination, we identified several candidates (DUBs and E2s) involved in the induction of cell death while overcoming acquired resistance against proteasome catalytic inhibitors. These candidates may represent attractive targets for developing specific inhibitors to counteract resistance to proteasome inhibitors.