A G protein-coupled receptor with structural characteristics of a biogenic amine GPCR was cloned from Schistosoma mansoni (SmGPCR). SmGPCR was codon-optimized and double-tagged with FLAG and His epitopes at the N- and C-terminal ends, respectively. Immunofluorescence experiments targeting these epitopes revealed that the expression of codon-optimized SmGPCR was highly increased compared to wild-type in mammalian cells. These studies also demonstrated that SmGPCR has a typical GPCR topology, the N-terminus being extracellular and C-terminus intracellular. Functional assays revealed that codon-optimized SmGPCR was responsive only to histamine, which caused a dose-dependent increase in intracellular Ca2+ (EC50 = 0.54 +/- 0.05 muM), but not cAMP, consistent with a Gq pathway of signal transduction. In vitro behavioral studies showed that treatment of S. mansoni cercaria with exogenous histamine caused a dose-dependent increase in the motility of the parasite.

Els receptors d'adenosina són receptors acoblats a proteïna G classificats en A1, A2A, A2B i A3 en funció del grau d'afinitat pel seu agonista endogen, l'adenosina. Els receptors A1 i A3 interaccionen amb l'adenilat ciclasa (AC) inhibint la seva activitat i els receptors A2A I A2B activant-la. El receptor d'adenosina A1 (A1R) té un paper clàssicament neuroprotector mentre que el receptor A2A (A2AR) està associat a neurotoxicitat, dany neuronal i mort cel·lular. Les malalties neurodegeneratives són un conjunt de patologies que presenten dèficit cognitiu o alteracions motores en funció del tipus neuronal que degenera i que, bioquímicament s'anomenen proteïnopaties, perquè acumulen agregats proteics.L'objectiu d'aquest estudi ha estat l'anàlisi dels nivells d'expressió dels receptors d'adenosina en la malaltia de grans argiròfils (AGD), la malaltia d'Alzheimer (AD) i la malaltia de Parkinson (PD). En aquest punt, hem descrit un increment dels receptors A1R en l'hipocamp de pacients amb AGD i un increment dels receptors A1R i A2AR en el còrtex frontal de pacients amb AD des de estadiatges preclínics. Paral·lelament s'ha detectat un augment dels receptors A2AR en el nucli estriat de pacients amb PD que encara no han rebut tractament farmacològic. Altres autors havien descrit increments del receptor tot i que sempre associat a tractaments de llarga durada amb Levodopa (L-Dopa). A partir d'aquest resultat i per tal de conèixer el mecanisme molecular implicat en l'increment patològic del receptor vam afrontar el segon objectiu del treball: l'estudi de la regulació transcripcional del gen ADORA2A, gen que codifica pel receptor A2AR.Es va estudiar el percentatge de metilació de l'extrem 5'UTR del gen ADORA2A, tant en línies cel·lulars com en l'estriat de pacients amb PD i el paper de dos factors de transcripció, ZBP-89 i Yin-yang 1(YY1), en l'increment patològic del receptor. La metilació de l'ADN és un dels principals mecanismes de repressió de l'expressió gènica. Hem demostrat que el percentatge de metilació en l'extrem 5'UTR del gen ADORA2A controla els nivells d'ARNm del receptor en línies cel·lulars tot i que no hem observat canvis en el percentatge de metilació en el nucli estriat de pacients amb PD respecte els pacients controls. A més, hem demostrat, per primera vegada, que els factors de transcripció ZBP-89 i YY1 actuen com activador i repressor, respectivament, del receptor A2AR en les cèl·lules SHSY-5Y. En els pacients de PD no s'han observat canvis en l'expressió del ZBP-89 però sí, un increment tant a nivell d' ARNm com de proteïna del YY1. Conjuntament, per microscopia confocal, hem observat que YY1 està localitzat tant als nuclis de les cèl·lules positives com negatives pel receptor A2AR. En conclusió, el percentatge de metilació no varia en les regions analitzades entre controls i patològics. Tot i així, hem demostrat un increment patològic de YY1 en pacients amb PD i, com que està descrit que els nivells d'AMPc controlen l'expressió del factor de transcripció, ens permet proposar la hipótesis per la qual un increment de YY1 pot representar un mecanisme de regulació retrògrada del A2AR per tal de reduir-ne els nivells a PD. / Adenosine is a nucleoside distributed throughout the entire organism as an intermediary metabolite. At the extracellular level, adenosine plays multiple physiologic roles, interacting with specific receptors: A1, A2A, A2B and A3. Adenosine receptors A1 and A2B have been related in neuroprotective role and adenosine activity through A2 receptors (A2ARs) can give rise to neurotoxicity, neuronal damage and cellular death. In this work we have devolve two main points. First of all we characterized the adenosine receptor expression levels in neurodegenerative disease: Argirofilic grains disease (AGD), Alzheimer disease (AD) and Parkinson disease (PD). We described an increase of A1R in hippocampus of patients with AGD, increased levels of A1 and A2A in frontal cortex of patients with AD in early stages. We observed an increase of de A2A levels in striatum in PD patients with any treatment at all. Trying to know the molecular reason of the pathological expression levels of A2A R we studied the percent of methylation of 5'UTR of ADORA2A which codifies by A2aR in cell lines and in post-mortem tissue of patients of PD. We conclude that DNA methylation plays a role in a constitutive A2AR cell surface level, but no changes were observed comparing PD patients and controls. By the other hand, we studied the role of two transcription factors ZBP-89 and Yin-yang 1 (YY1) in the A2AR expression level. We conclude ZBP-89 active and YY1 repress the expression of the receptor in SHSY-5Y lines.

The shock prod defensive burying test has proven incredibly reliable and instrumental in determining the underpinnings of normal anxiety in rodents. Largely ignored in tests of defensive burying, however, is the capacity for individual animals to display marked variations in active and passive coping behaviors. To unmask the neurobiological correlates of this behavioral differentiation, rats were exposed to a mousetrap that was remotely triggered upon approach to remove the quality of pain. This design invited striking variations in defensive burying behavior levels, in which some rats either buried robustly or showed little to no levels of defensive burying. Furthermore, differences in burying behavior were associated with marked differences in the central expression of arginine vasopressin (AVP) and oxytocin (OT). Thus, relative to animals showing no significant levels of defensive burying activity, rats showing sustained elevations in defensive burying expressed higher levels of AVP mRNA and increased numbers of androgen receptor positive cells in the medial amygdala and posterior bed nuclei of the stria terminalis, brain regions that integrate emotional appraisal and sensory information. In contrast, animals showing little to no defensive burying responses expressed relatively higher levels of AVP and OT mRNA within the supraoptic nucleus and subregions of the paraventricular nucleus of the hypothalamus responsible for neuroendocrine and autonomic function. CRH mRNA levels did not vary as a function of burying activity in the central nucleus of the amygdala, the anterior division of the bed nuclei of the stria terminalis, nor in the paraventricular nucleus. These findings suggest a role for central AVP and OT in mediating differential defensive behaviors, and demonstrate the utility of using a pain free test of conditioned defensive burying as a framework for exploring individual differences in behavioral coping and neuroendocrine capacity.

Novel approaches to cancer treatment in the context of Gene Therapy have been gaining popularity as an alternative to conventional therapies which have proven to lack specificity, resulting in tumour cell resistance, tumour progression and mortality. As a consequence the use of adenoviruses has been widely developed not only as a replication deficient vector for gene therapy but also as a replication competent oncolytic agent designed to selectively target and kill tumour cells. Unfortunately their success in clinical application has been limited, and it has been suggested that a lack of the primary viral attachment receptor 'CAR' could be a barrier to infection by limiting access to target cells. If Ad/CAR binding is the rate limiting step for successful Ad therapy, it is essential to establish a CAR expression profile in normal and tumour tissue, and in tumour progression, to enable more effective targeted therapy. Furthermore, in the context of using adenovirus as an anticancer strategy by exploiting its replicative lysis, it is important to explore whether Ad success is affected by CAR expression and to identify factors downstream of CAR that may be influential in this process. In the first experimental chapter, an in vivo immunohistochemical analysis of tissue array slides determined CAR expression in a range of normal and tumour tissue. CAR was differentially expressed dependent on cell of origin, with normal stem cells and basal cells displaying very high CAR, signifying its importance in early development and differentiation. Epithelial cells were also high in CAR but its expression was negligible in mesenchymal, lymphoid and neural cells. This trend was also reflected in most tumour tissue albeit with a general decrease in CAR compared to corresponding normal tissue of the same organ. An exception was the blastic tumours which displayed high CAR reflecting their embryonic state of derivation. CAR expression also decreased in high grade, poorly differentiated tumours of the prostate, stomach and breast compared to their well differentiated counterparts. In the second experimental chapter, a more comprehensive study of breast cancer biopsy specimens was undertaken, to determine both the expression of CAR and the tumour suppressor gene p53 in relation to tumour grade. The rationale being that both loss of CAR expression and p53 mutation (resulting in loss of function), have been associated with tumour progression. It is possible that CAR and p53 interact directly or indirectly and may be modulated by each other. This study revealed a decrease in both CAR and hormone receptor expression and an increase in p53 'mutational' status with increasing tumour grade. These three factors when compared independently to tumour grade are statistically significant associations, implying that CAR expression and hormone responsiveness decrease with tumour progression and p53 function is compromised or lost via mutation. There was also a significant association between CAR expression and hormone receptor status, however a significant association between CAR expression and p53 status within the tumour grades was not found. Treatment outcome with Ads will also depend on defining factors downstream of CAR attachment that affect adenovirus 'permissivity', which is ultimately measured by viral replication and cell death, relying on the bystander effect to eradicate all tumour cells. The in vitro analysis revealed statistically significant associations between CAR receptor expression, 'infectivity' (virus infection) and permissivity. Cell lines that were more susceptible to Ad5 were generally of epithelial origin, had high CAR, and were easily infected. However there were exceptions and CAR was not the sole determinant in adenovirus cell entry nor in its ability to replicate and kill the cell. Permissivity was also related to p53 status. Thus, although CAR expression may indeed be a limiting factor, it is apparent that a combination of other events contributes to a deficient infection, especially in the deregulated tumour environment. The results presented in this thesis clearly demonstrate that there is more to the story of 'CAR' which hints that its role in viro-oncotherapy is not limited solely to its function as an attachment receptor for adenovirus but may also involve its function as a cell adhesion molecule and signal transducer. The further elucidation of these aspects of CAR�s potential role in the scheme of tumour biology may alter the course and strategy of cancer therapy in the future.

Errata is tipped in between leaf 9 & 10. / Bibliography: leaves 209-235. / 235 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Focusses specifically on the role of acetylcholine in the circadian timing system of mammals, using the rat as an animal model. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1999

Thesis (M.S.)--Brigham Young University. Dept. of Physiology and Developmental Biology, 2006. / Includes bibliographical references (p. 47-50).

Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--University of Adelaide, Dept. of Physiology, 1984. / Includes bibliographical references (leaves 118-161).

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 115-123). Also available in electronic version.