No Brasil, como no mundo, o carcinoma epidermóide bucal está entre os dez tipos mais comum de câncer e acomete mais de 13 mil pessoas por ano. Apesar de ser um sério problema devido a sua morbidade e mortalidade, alguns casos desta doença têm um comportamento biológico menos agressivo. A proteína ciclina D1, depois que forma complexos com as proteínas CDK4 e CDK6, tem como principal função fosforilar a proteína Retinoblastoma. Após sua fosforilação, a proteína libera um fator de transcrição, o E2F, que leva a célula à progressão da fase G1 para fase S do ciclo celular. A proteína c-jun, que faz parte do fator de transcrição AP-1, tem participação ativa no ciclo celular, principalmente durante a transcrição da fase G0 a G1. O gene retinoblastoma é um supressor de tumor. Este gene codifica uma fosfoproteína nuclear, que recebe o mesmo nome. Essa proteína regula o ciclo celular através de múltiplas funções. Também regula outros processos que afetam a proliferação celular, a diferenciação terminal e a apoptose. O HPV é um vírus de DNA que é encontrado em vários tipos de câncer e é o principal agente etiológico do carcinoma de colo uterino. Este trabalho comparou a expressão das proteínas ciclina D1, c-jun e do retinoblastoma em carcinomas epidermóides de baixo e alto grau de malignidade e tentou analisar se o HPV é um fator etiológico desta neoplasia. Apesar das lesões de baixo grau de malignidade expressarem as proteínas num maior número de células que as lesões de alto grau, só houve diferença estatística, entre os dois grupos estudados, para a proteína do retinoblastoma. Não foi encontrado o DNA do HPV em nenhum dos casos estudados. De acordo com este trabalho e com a literatura, a proteína do retinoblastoma é expressa em um número menor de células em carcinomas epidermóides bucais mais agressivos e o HPV não é um agente etiológico de todos os casos desta doença / In Brazil, as in the world, the oral squamous cell carcinoma is among the ten more common types of cancer e affects more than 13 thousand of people by year. Even though it is a serious problem due to its morbidity and mortality, some cases of this disease have a less aggressive biological behavior. The cyclin D1 protein after it forms complexes with the CDK4 and CDK6 proteins has as main function phosphorylate the Retinoblastoma protein. After its prosphorylation, the protein releases a transcription factor, the E2F, that leads the cell to the progression from the phase G1 to the phase S of the cell cycle. The c-jun protein, that is part of the transcription factor AP-1, has active participation in the cell cycle, mainly during the transcription from the phase G0 to G1. The retinoblastoma gene is a tumour suppressor. This gene codifies a nuclear phosphoprotein that receives the same name. This protein regulates the cell cycle through multiple functions. It also regulates other processes that affect the cell proliferation, the terminal differentiation and apoptosis. The HPV is a DNA virus that is found in many types of cancer and is the main etiological agent of the cervical cancer. This study compared the protein expression of the cilin D1, c-jun and retinoblastoma in low and high grade squamous cell carcinoma and tried to analyze if the HPV is a etiological factor for this neoplasm. In spite of the low grade of malignancy lesions express the protein in a greater number of cells than in the high grade lesion, there only was statistical difference, among the two studied groups, for the retinoblastoma protein. It was not found DNA of the HPV in any of the studied cases. According with this study and with the literature the retinoblastoma protein is expressed in a lower number of cells in the more aggressive oral squamous cell carcinomas and the HPV is not the etiological agent in all of the cases of this disease.

O carcinoma adenóide cístico e o adenocarcinoma polimorfo de baixo grau de malignidade são neoplasmas de glândulas salivares. O carcinoma adenóide cístico pode apresentar-se em glândulas salivares maiores e menores, porém o adenocarcinoma polimorfo de baixo grau de malignidade acomete principalmente as glândulas salivares menores distribuidas na cavidade oral. Ambos os tumores compartilham muitas características comuns, como a alta propensão de invasão perineural e o padrão de infiltracão: sólido, tubular e cribriforme. Mas o carcinoma adenoide cístico e o adenocarcinoma polimorfo de baixo grau são tipos distintos de adenocarcinomas com prognóstico diferente, que ocasionalmente podem resultar em um diágnóstico errado. As proteínas c-jun e junB são membros da familia JUN, capazes de homodimerizar ou heterodimerizar com c-fos ou com outras proteinas bzip. Evidências das funcões específicas das subunidades do AP-1 foram mostradas por cjun e junB, que atúam antagónicamente no controle da transformação celular, diferenciação e expressão do AP-1 dependente do gene alvo. Mas a função de ambos é complexa e pode depender do tipo celular. O objetivo deste estudo foi determinar a expressão imunoistoquímica das proteínas c-jun e junB em 13 casos de carcinoma adenoide cístico e 12 de adenocarcinoma polimorfo de baixo grau de malignidade de glándulas salivares. Espécimes de mucosa normal foram incluídos e evidenciaram forte marcação nuclear e citoplasmática para junB e c-jun respectivamente. No presente estudo, independente da arquitetura histológica, ambos tumores mostraram muitas células tumorais com marcação nuclear e citoplasmática para a proteína c-jun e ausente para a proteína junB. As lesões do adenocarcinoma polimorfo de baixo grau de malignidade expressaram um maior número de células com marcação nuclear quando comparados ao do carcinoma adenoide císticode de mais baixo grau. De acordo com este estudo e com alguns estudos publicados na literatura, a c-jun é expressa em tumores de baixo grau e parece estar mais relacionada à diferenciação celular do que à proliferação celular. / Adenoid cystic carcinoma and polymorphous low grade are salivary gland neoplasms. ACC can arise in both, major or minor salivary glands. However, Polymorphous lowgrade adenocarcinoma, occurs specifically in minor salivary glands dispersed in the oral cavity. They share many common histologic features, as infiltrating solid, tubular and cribiform patterns and also high propensity for perineural invasion. Nevertheless, adenoid cystic carcinoma and polymorphous low grade are distinct types of adenocarcinomas with different prognosis, which occasionally may result in a diagnostic pitfall. C-jun and junB are family JUN members that may form homodimerizes or heterodimerizes with c-fos or other bzip proteins. Evidence for specific functions of AP-1 subunits was shown for c-jun and junB, which act antagonistically to control cell transformation, differentiation and expression of AP-1 depending on the target genes. However, the role of both of them is complex and it depends on cell type. The aim of this study was to determine immunohistochemistry of c -jun and junB expression in 13 cases of adenoid cystic carcinoma and 12 cases of polymorphous carcinoma low-grade adenocarcinoma of salivary glands. Moreover slides of normal mucosa were included and there were strong nuclei and cytoplasmic for junB and c-jun respectly. In the present study, independent of the histologic architecture, in both tumors shown many tumoral cells presented nuclear and cytoplasmic staining of c-jun and were absent to the protein junB. In polymorphous low-grade adenocarcinoma lesions expressed in a greater number cells staining than in the adenoid cystic carcinoma of the most lowgrade. According with this study and with some studies of the literature, the c-jun is expressed in low-grade tumors and seems to be related to cell differentiation more than with cell proliferation.

No Brasil, como no mundo, o carcinoma epidermóide bucal está entre os dez tipos mais comum de câncer e acomete mais de 13 mil pessoas por ano. Apesar de ser um sério problema devido a sua morbidade e mortalidade, alguns casos desta doença têm um comportamento biológico menos agressivo. A proteína ciclina D1, depois que forma complexos com as proteínas CDK4 e CDK6, tem como principal função fosforilar a proteína Retinoblastoma. Após sua fosforilação, a proteína libera um fator de transcrição, o E2F, que leva a célula à progressão da fase G1 para fase S do ciclo celular. A proteína c-jun, que faz parte do fator de transcrição AP-1, tem participação ativa no ciclo celular, principalmente durante a transcrição da fase G0 a G1. O gene retinoblastoma é um supressor de tumor. Este gene codifica uma fosfoproteína nuclear, que recebe o mesmo nome. Essa proteína regula o ciclo celular através de múltiplas funções. Também regula outros processos que afetam a proliferação celular, a diferenciação terminal e a apoptose. O HPV é um vírus de DNA que é encontrado em vários tipos de câncer e é o principal agente etiológico do carcinoma de colo uterino. Este trabalho comparou a expressão das proteínas ciclina D1, c-jun e do retinoblastoma em carcinomas epidermóides de baixo e alto grau de malignidade e tentou analisar se o HPV é um fator etiológico desta neoplasia. Apesar das lesões de baixo grau de malignidade expressarem as proteínas num maior número de células que as lesões de alto grau, só houve diferença estatística, entre os dois grupos estudados, para a proteína do retinoblastoma. Não foi encontrado o DNA do HPV em nenhum dos casos estudados. De acordo com este trabalho e com a literatura, a proteína do retinoblastoma é expressa em um número menor de células em carcinomas epidermóides bucais mais agressivos e o HPV não é um agente etiológico de todos os casos desta doença / In Brazil, as in the world, the oral squamous cell carcinoma is among the ten more common types of cancer e affects more than 13 thousand of people by year. Even though it is a serious problem due to its morbidity and mortality, some cases of this disease have a less aggressive biological behavior. The cyclin D1 protein after it forms complexes with the CDK4 and CDK6 proteins has as main function phosphorylate the Retinoblastoma protein. After its prosphorylation, the protein releases a transcription factor, the E2F, that leads the cell to the progression from the phase G1 to the phase S of the cell cycle. The c-jun protein, that is part of the transcription factor AP-1, has active participation in the cell cycle, mainly during the transcription from the phase G0 to G1. The retinoblastoma gene is a tumour suppressor. This gene codifies a nuclear phosphoprotein that receives the same name. This protein regulates the cell cycle through multiple functions. It also regulates other processes that affect the cell proliferation, the terminal differentiation and apoptosis. The HPV is a DNA virus that is found in many types of cancer and is the main etiological agent of the cervical cancer. This study compared the protein expression of the cilin D1, c-jun and retinoblastoma in low and high grade squamous cell carcinoma and tried to analyze if the HPV is a etiological factor for this neoplasm. In spite of the low grade of malignancy lesions express the protein in a greater number of cells than in the high grade lesion, there only was statistical difference, among the two studied groups, for the retinoblastoma protein. It was not found DNA of the HPV in any of the studied cases. According with this study and with the literature the retinoblastoma protein is expressed in a lower number of cells in the more aggressive oral squamous cell carcinomas and the HPV is not the etiological agent in all of the cases of this disease.

No description available.

No description available.

Dementia causes an increasing social and economic burden worldwide, demanding action regarding its diagnosis, treatment and everyday management. Recent years have seen many advances in neurodegeneration research, but the search for new truly disease modifying therapies for Alzheimer's disease (AD) and frontotemporal dementia (FTD) has so far not been successful. This is mainly due to a lack of understanding of the precise intracellular events that lead up to neuronal dysfunction in early and in late stages of the disease. This thesis describes the approaches taken to extend the current knowledge about the intracellular effects of neuronal amyloid-beta and the signalling pathways causing neuronal death or disturbed synaptic function in dementia. Endophilin-1(Ep-1), amyloid-binding alcohol dehydrogenase (ABAD), peroxiredoxin-2 (Prx-2) and the EF-hand domain family, member D2 (EFHD2) have been found to be elevated in the human brain with dementia and in mouse models for frontotemporal lobar degeneration (FTLD) or AD. The expression of these proteins as well as the expression of c-Jun N-terminal kinase (JNK), c-Jun and APP were analysed by western blotting and real-time PCR in human brains affected by AD or FTLD as well as in mouse models for AD. This provided a new insight into the regulation of these proteins in relation to each other in the ageing brain and uncovered a new potential link between elevated levels of EFHD2, Prx-2 and APP in FTLD. By studying the effects of the overexpression of Ep-1 in neurons, this research has led to a better understanding of its role in JNK-activation. It furthermore verified a protective role for Prx-2 against neurotoxicity and pointed towards a new function for Prx-2 in the regulation of JNK-signalling. The analysis of the effect of increased levels of EFHD2 uncovered for the first time its involvement in the PI3K-signalling cascade in neuronal cells. The current work has therefore contributed to the knowledge about the cellular processes that are affected by Ep-1, Prx-2 and EFHD2 in different types of dementia and will greatly benefit future research into their actions in the neuronal network.

Chronic hyperglycemia, a hallmark of type 2 diabetes, can decrease β-cell function and mass (β-cell glucotoxicity); however, the mechanisms are incompletely understood. The objective was to examine the mechanisms of β-cell glucotoxicity using in vivo and ex vivo models. The hypothesis is that oxidative stress plays a causal role in high glucose-induced β-cell dysfunction in vivo via pathways that involve endoplasmic reticulum (ER) stress and JNK. The model of β-cell glucotoxicity was achieved by prolonged i.v. glucose infusion (to achieve hyperglycemia). In Study 1, 48h glucose infusion increased total and mitochondrial superoxide levels in islets, and impaired β-cell function in vivo and ex vivo. Co-infusion of the superoxide dismutase mimetic Tempol decreased total and mitochondrial superoxide, and prevented high glucose-induced β-cell dysfunction in vivo and ex vivo. These results suggest that increased superoxide generation plays a role in β-cell glucotoxicity. In Study 2, 48h glucose infusion increased activation of the unfolded protein response (XBP-1 mRNA splicing and phospho-eIF2α levels). This was partially prevented by Tempol. Co-infusion of the chemical chaperone 4-phenylbutyrate with glucose decreased spliced XBP-1 levels, and prevented high glucose-induced β-cell dysfunction in vivo and ex vivo. Co-infusion of 4-phenylbutyrate also decreased total and mitochondrial superoxide induced by high glucose. These results suggest that 1) ER stress plays a causal role in high glucose-induced β-cell dysfunction, and 2) there is a link between oxidative stress and ER stress in high glucose-induced β-cell dysfunction in vivo. In Study 3, JNK inhibition using the inhibitor SP600125 in rats or JNK-1 null mice prevented high glucose-induced β-cell dysfunction ex vivo and in vivo. SP600125 prevented high-glucose-induced β-cell dysfunction without decreasing total and mitochondrial superoxide levels. Both Tempol and 4-phenylbutyrate prevented JNK activation induced by high glucose. These results suggest a role of JNK activation in high glucose-induced β-cell dysfunction downstream of increased superoxide generation and ER stress in vivo. Together, the results suggest that 1) oxidative stress, ER stress and JNK activation are causally involved in β-cell glucotoxicity, and 2) High glucose-induced oxidative stress and ER stress are linked, and both impair β-cell dysfunction via JNK activation in vivo.

Chronic hyperglycemia, a hallmark of type 2 diabetes, can decrease β-cell function and mass (β-cell glucotoxicity); however, the mechanisms are incompletely understood. The objective was to examine the mechanisms of β-cell glucotoxicity using in vivo and ex vivo models. The hypothesis is that oxidative stress plays a causal role in high glucose-induced β-cell dysfunction in vivo via pathways that involve endoplasmic reticulum (ER) stress and JNK. The model of β-cell glucotoxicity was achieved by prolonged i.v. glucose infusion (to achieve hyperglycemia). In Study 1, 48h glucose infusion increased total and mitochondrial superoxide levels in islets, and impaired β-cell function in vivo and ex vivo. Co-infusion of the superoxide dismutase mimetic Tempol decreased total and mitochondrial superoxide, and prevented high glucose-induced β-cell dysfunction in vivo and ex vivo. These results suggest that increased superoxide generation plays a role in β-cell glucotoxicity. In Study 2, 48h glucose infusion increased activation of the unfolded protein response (XBP-1 mRNA splicing and phospho-eIF2α levels). This was partially prevented by Tempol. Co-infusion of the chemical chaperone 4-phenylbutyrate with glucose decreased spliced XBP-1 levels, and prevented high glucose-induced β-cell dysfunction in vivo and ex vivo. Co-infusion of 4-phenylbutyrate also decreased total and mitochondrial superoxide induced by high glucose. These results suggest that 1) ER stress plays a causal role in high glucose-induced β-cell dysfunction, and 2) there is a link between oxidative stress and ER stress in high glucose-induced β-cell dysfunction in vivo. In Study 3, JNK inhibition using the inhibitor SP600125 in rats or JNK-1 null mice prevented high glucose-induced β-cell dysfunction ex vivo and in vivo. SP600125 prevented high-glucose-induced β-cell dysfunction without decreasing total and mitochondrial superoxide levels. Both Tempol and 4-phenylbutyrate prevented JNK activation induced by high glucose. These results suggest a role of JNK activation in high glucose-induced β-cell dysfunction downstream of increased superoxide generation and ER stress in vivo. Together, the results suggest that 1) oxidative stress, ER stress and JNK activation are causally involved in β-cell glucotoxicity, and 2) High glucose-induced oxidative stress and ER stress are linked, and both impair β-cell dysfunction via JNK activation in vivo.

Defining the mechanics and consequences of protein adduction is crucial to understanding the toxicity of reactive electrophiles. Application of tandem mass spectrometry and data analysis algorithms enables detection and mapping of chemical adducts at the level of amino acid sequence. Nevertheless, detection of adducts does not indicate relative reactivity of different sites. In this dissertation I describe a method to measure the kinetics of competing adduction reactions at different sites on the same protein using quantitative mass spectrometry. Adducts are formed by electrophiles at Cys-14 and Cys-47 on the metabolic enzyme glutathione-S-transferase P1-1 and accompanied by a loss of enzymatic activity. Relative quantitation of protein adducts was done by tagging N-termini of peptide digests with isotopically labeled phenyl isocyanate and tracking the ratio of light-tagged peptide adducts to heavy-tagged reference samples. This method was used to measure rate constants for adduction at both positions with two different model electrophiles, IAB and BMCC. The results indicate that Cys-47 was approximately 2-3-fold more reactive toward both electrophiles than was Cys-14. This result was consistent with the relative reactivity of these electrophiles in a complex proteome system. Quantitative analyses of protein modifications provide a means of determining the reactivity and selectivity of damaging protein modifications in chemical toxicity.Another area of study explored in this dissertation is looking at the effects of protein alkylation on activating cellular signaling pathways, specifically the JNK signaling pathway. Protein adduction has been shown to be selective between different alkylating agents. It would then be reasonable to think this selectivity of adduction translates to selectivity of downstream consequences or cellular events directly tied to specific adductions. My work will show how treatment of HEK293 cells with either IAB or BMCC leads to differences in activation of JNK signaling. In addition, I've been able to show a difference in selectivity of a number of adducted targets by each alkylating agent, which are directly involved in regulation of the JNK signaling pathway. These studies illustrate not only the significance of protein adduction, but the importance for continual research to better understand their behavior in living systems.

T cells are involved in cellular pathways which enable the immune system to protect us against infection and cancer. However, the same mechanisms also allow T cells to generate chronic inflammatory conditions, including autoimmunity and allergy. Thus a concerted effort has been made to try to understand how the immune system functions in order to inhibit responses which may have harmful effects on tissues and organs. There is a continued search for new immunosuppressants which can only be accomplished through a better understanding of the pathways that regulate T cell function. This includes the intracellular signalling pathways which modulate T cell proliferation and cytokine production. While the Mitogen-Activated Protein Kinases (MAPK), extracellular signal-regulated protein kinases (ERK) and p38 have received attention, the role of the stress-activated protein kinases or c-jun N-terminal kinases (JNK) remains controversial. To overcome some of the limitations in studying the role of JNK, a new approach was taken in this thesis. The investigations used recently described peptides (TAT-JIP[subscript]153-163 and TAT-JIP[subscript]153-172) derived from the scaffold protein, JIP-1, which have previously been demonstrated to act as JNK pathway inhibitors. The research characterised the specificity of these inhibitors to enable the appropriate interpretation of data. Using these inhibitors, we were able to show that JNK regulated human T cell proliferation and cytokine production in T cell responses induced independently of TCR ligation (PHAPMA) or via the TCR (anti-CD3-anti-CD28 antibodies, Mixed Lymphocyte Reaction (MLR), Tetanus Toxoid and Der p 2). The data demonstrated that JNK primarily regulated the Th1 cytokine patterns (IFNγ, IL2 and LT) with minimal effect on Th2 cytokine production (IL4, IL10) in response to all stimulatory models. However, while the JNK signalling pathway promoted T cell proliferation and cytokine production in response to PHA-PMA, the pathway depressed these responses following stimulation with anti-CD3-anti-CD28 antibodies and Tetanus Toxoid. Thus activation of JNK with microbial pathogens such as Pseudomonas aeruginosa (PA), which non-specifically activate T cells, may promote lymphocyte proliferation and the release of Th1 cytokines, such as IFNγ. In contrast, JNK activation resulting from engagement of the T cell receptor (TCR) (i.e. Tetanus Toxoid), down-regulates Th1 cytokine production. Therefore, it is likely that the JNK signalling pathway may dampen the development of chronic inflammatory conditions resulting from infection with intracellular parasites and autoimmune diseases. In contrast to Tetanus Toxoid, responses to the recombinant house dust mite allergen, Dermatophagoides pteronyssinus (Der p 2) were promoted by JNK, leading to an increase in Th1 cytokine production. Thus the results suggest that the use of JNK inhibitors could exacerbate both inflammatory conditions (autoimmunity and allergy) and this may also apply to p38 but not the ERK signalling pathway. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1374669 / Thesis (Ph.D.) - University of Adelaide, School of Molecular and Biomedical Science, 2009