Hypothalamic gonadotropin-releasing hormone (GnRH) (GnRH I) is the central regulator of the mammalian reproductive system. Most vertebrates studied also possess a second form of GnRH, GnRH II. GnRH I acts on its cognate G proteincoupled receptor (GPCR) on pituitary gonadotropes and activates Gq/11-mediated signalling pathways to stimulate the biosynthesis and the release of luteinising hormone (LH) and follicle-stimulating hormone (FSH). Both GnRHs have also been suggested to inhibit cellular proliferation, an action which has largely been proposed to be mediated by the coupling of the receptor to Gi/o. However, the range of G proteins activated by the GnRH receptor and the signalling cascades involved in inducing antiproliferation remain controversial. To delineate the G protein coupling selectivity of the mammalian GnRH receptor and to identify the signalling pathways involved in GnRH I-mediated cell growth inhibition, I examined the ability of the receptor to interact with Gq/11, Gi/o and Gs in Gαq/11 knockout MEF cells. My results indicate that the receptor is unable to interact with Gi/o but can signal through Gq/11. Additionally, my data do not support the suggestion of GnRH receptor-Gs interaction. Furthermore, I show that the GnRH Iinduced inhibition of cell growth is dependent on Gq/11, src and extracellular signal regulated kinase (ERK) but is independent of the activity of protein kinase C (PKC), Ca2+, jun-N-terminal kinase (JNK) or P38. Based on these findings and previous research within our group, I propose a mechanism whereby GnRH I may induce antiproliferation. Previous studies from our laboratory suggest that the GnRH receptor can adopt distinct active conformations in response to the binding of GnRH I and GnRH II. These data thus account for our hypothesis of ligand-induced selective signalling (LiSS). Given my previous results, I examined the ability of the GnRH receptor to couple to G12/13. My work indicates that the receptor can directly activate G12/13 and the downstream signalling cascades associated with this G protein family. Indeed, I provide evidence, in several cellular backgrounds, to suggest that GnRH receptor- G12/13-mediated signalling is involved in the regulation of GnRH-induced MAPK activity, SRE-driven gene transcription and cytoskeletal reorganisation. Furthermore, I propose a role for these G proteins in the transcriptional regulation of LHβ and FSHβ. Finally, I confirm previous results from our laboratory indicating that the GnRH receptor may interact with src Tyr kinase and show that GnRH I but not GnRH II may, independently of Gq/11, stimulate the Tyr phosphorylation and thus the activation of this protein. I propose that this differential signalling accounts for the distinct effects of GnRH I and GnRH II on cellular morphology and SREpromoted transcriptional activity. The research presented within this thesis provides evidence to refute published conclusions based on largely circumstantial experimental data, describes novel GnRH receptor signalling pathways and offers support for the concept of LiSS. It may assist in the development of new therapeutic compounds which selectively target one GnRH-mediated signalling pathway while bypassing others.

G protein-coupled receptors (GPCRs) form a link between the cell and their environment when signaling pathways are activated upon ligand binding. However, the ligands and functions for many GPCRs remain to be determined. G protein-coupled receptor 50 (GPR50) is one such orphan, and its exact role is yet unknown. There is however emerging functional and genetic evidence suggesting a function for GPR50 in psychiatric illness and lipid metabolism. It was hypothesised that investigating GPR50’s protein-protein interactions would lead to a greater understanding of the role of GPR50 in normal brain functioning and in mental illness. Putative protein interactors were initially isolated by a yeast two-hybid study and were further tested here. To address GPR50’s links to mental illness, the GPR50∆502-505 deletion variant associated with mood disorders was also investigated. To test this hypothesis I sought to confirm some of the key yeast two-hybrid interactions. Using co-immunoprecipitation and immunocytochemistry the interaction of GPR50 with reticulon family members Nogo-A, Nogo-C and RTN3, and with cell-cell adhesion molecule CDH8 and lipid-associated protein ABCA2 were validated. In order to identify the location of interactions, subcellular fractionation of mouse brain and rt-PCR and immunohistochemistry in developing and adult mouse brain were performed. GPR50 and several interactors were found to be enriched at the synapse by subcellular fractionation of whole adult brain, and at embryonic day 18 (E18) and 5 weeks by rt-PCR. Colocalisation of GPR50 and interactors was found in the amygdala, hypothalamus, cortex and specific brain stem nuclei by immunohistochemistry. The discovery of GPR50 expression in noradrenergic, serotonergic and dopaminergic nuclei in the adult brain stem suggests a further role for GPR50 in neurotransmitter signaling and stress. To investigate the function of GPR50 two assays were performed that measure processes which are known to be affected by Nogo and RTN3: The first assay was a neurite outgrowth assay in Neuroscreen-1 cells, a PC12 cell clone. A significant increase in neurite length was detected after transient overexpression of GPR50 and this effect was increased in the GPR50∆502-505/T532A variant. Additionally GPR50-overexpression resulted in an increase in filopodia formation suggesting a role in actin dynamics. As a second functional assay in vitro BACE1 activity assays were performed in HEK293 cells. GPR50 but not GPR50∆502-505/T532A overexpression resulted in a significant increase in BACE1 activity. Lastly a final series of pilot experiments were performed to gain insight into the secondary structure of the C-terminal domain and the effects of the polymorphisms on structure. The 35kDa GPR50 C-terminal domain was purified and Circular Dichroism studies indicated a predominantly unstructured protein with increased a- helical content in the GPR50∆502-505 variant. The results in this thesis indicate a role for GPR50 in neuronal development and synaptic functioning. The results also strengthen an association with major mental illness, with links to several disease mechanisms.

The calcium sensing receptor (CaSR) is a G-protein coupled receptor (GPCR) that plays a central role in calcium homeostasis. Loss-of-function mutations of the CaSR cause familial hypocalciuric hypercalcaemia type 1 (FHH1), whilst gain-of-function mutations are associated with autosomal dominant hypocalcaemia (ADH). However, 35% of cases of FHH and 60% of cases of ADH are not due to CaSR mutations. This thesis demonstrates that FHH type 2 (FHH2) and the new clinical disorder, ADH type 2 (ADH2), are due to loss- and gain-of-function mutations in the G-protein subunit, Gα11, respectively. The CaSR signals through Gα11 and FHH2-associated mutations are shown to exert their effects through haploinsufficiency. Three-dimensional modelling of ADH2-associated Gα11 mutations predicts impaired GTPase activity and increases in the rate of GDP/GTP exchange. Furthermore, mouse models of FHH2 and ADH2 have been identified and re-derived to enable in vivo studies of the role of Gα11 in calcium homeostasis. I also demonstrate that FHH3 is due to loss-of-function mutations in the adaptor protein 2 sigma subunit, AP2σ2, which exert dominant-negative effects. AP2σ2 is a component of the adaptor protein 2 (AP2), which is a crucial component of clathrin-coated vesicles (CCV) and facilitates clathrin-mediated endocytosis of plasma membrane components such as GPCRs. All of the identified FHH3-associated mutations affect the Arg15 residue of AP2σ2, which forms key polar contacts with CCV cargo proteins. This thesis proposes that FHH3-associated AP2σ2 mutations impair CaSR internalisation and thus negatively impact on CaSR signalling. In addition, these studies show that these signalling defects can be rectified by the use of the CaSR allosteric modulator cinacalcet, which may represent a useful therapeutic modality for FHH3 patients. In summary, FHH2 is due to loss-of-function mutations in Gα11 causing haploinsufficiency, whilst FHH3 is due to loss-of-function mutations in AP2σ2, which exert dominant-negative effects. In contrast, ADH2 is due to gain-of-function mutations in Gα11.

Thesis advisor: Marc A.T. Muskavitch / Malaria is a life-threatening infectious disease caused by inoculation of the apicomplexan Plasmodium parasite into vertebrate hosts. Transmission of the parasite is mediated by the Anopheles mosquito, which has the capacity to efficiently transmit the parasite from host to host, as the disease vector. There are many factors that make anopheline mosquitoes competent vectors for disease transmission. The hematophagous (blood-feeding) behavior of the female mosquito is one of most fundamental factors in physical transmission of parasites, because the ingestion of blood from an infected host allows parasite entry into the mosquito and the completion of parasite sexual reproduction. In addition to this blood-feeding behavior, there are a host of biological (i.e., parasite replication) and behavioral factors (i.e., mosquito chemosensation, host preference) that contribute to the high vectorial capacity of these vector species. There are over four hundred Anopheles species worldwide, approximately forty of which are considered epidemiologically critical human malaria vectors. Anopheles gambiae, the primary vector in malaria-endemic sub-Saharan Africa, is responsible for the largest number of malaria cases in the world and is therefore one of the most important vectors to study and target with control measures. Currently, vector-targeted control strategies remain our most effective tools for reduction of malaria transmission and incidence. Although control efforts based on the deployment of insecticides have proven successful in the past and are still widely used, the threat and continuing increases of insecticide resistance motivate the discovery of novel insecticides. In this thesis, I provide evidence that G protein-coupled receptors (GPCRs) may serve as “druggable” targets for the development of new insecticides, through the modulation of developmental and sensory processes. In Chapter II, “A critical role for the Drosophila dopamine 1-like receptor Dop1R2 at the onset of metamorphosis,” I provide evidence supporting an essential role for this receptor in Drosophila melanogaster metamorphosis via transgenic RNA interference and pharmacological methods. In An. gambiae, we find that the receptor encoded by the mosquito ortholog GPRDOP2 can be inhibited in vitro using pharmacological antagonists, and that in vivo inhibition with such antagonists produces pre-adult lethality. These findings support the inference that this An. gambiae dopamine receptor may serve as a novel target for the development of vector-targeted larvicides. In Chapter III, “RNAi trigger delivery into Anopheles gambiae pupae,” I describe the development of a method for injection directly into the hemolymph of double strand RNA (dsRNA) during the pupal stage, and I demonstrate that knockdown of the translational product of the SRPN2 gene occurs efficiently, based on reductions in the levels of SRPN2 protein and formation of melanized pseudo-tumors, in SRPN2 knockdown mosquitoes. This method was developed for rapid knockdown of target genes, using a dye-labeled injection technique that allows for easy visualization of injection quality. This technique is further utilized in Chapter IV, “Uncovering the Role of an Anopheles gambiae G Protein-Coupled Receptor, GPRGR2, in the Detection of Noxious Compounds,” where the role for GPRGR2 in the detection of multiple noxious compounds is elucidated. We find that pupal stage knockdown of this receptor decreases the ability of adult Anopheles gambiae to identify multiple noxious compounds. While these findings provide a strong link between GPRGR2 and a very interesting mosquito behavior, they may also provide opportunities to develop better field-based strategies (i.e., insecticides baited traps) for vector control. The goal of this thesis is to understand the functional roles of selected mosquito GPCRs that may serve as targets for the development of new vector-targeted control strategies. Exploiting these GPCRs genetically and pharmacologically may provide insights into novel vector control targets that can be manipulated so as to decrease the vectorial capacity of An. gambiae and other malaria vectors in the field, and thereby decrease the burden of human malaria. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.

Multiple sclerosis (MS) is a neurodegenerative disease associated with immune attack of the central nervous system (CNS) leading to neuronal and axonal loss. This affects neurotransmission accumulating residual disability and the development of neurological signs such as spasticity. Numerous studies have reported a beneficial role of cannabinoids in alleviating symptoms associated with neurological damage. The endocannabinoid system has been shown to control experimental spasticity in experimental autoimmune encephalomyelitis (EAE) an animal model of multiple sclerosis (MS). The orphan G-protein coupled receptor 55 (GPR55) has been identified as a functionally -related cannabinoid receptor known to be stimulated by lysophosphatidylinositol. In the current study a novel GPR55 gene knockoutmouse and GPR55-transfected cell line was obtained and characterised andthe function and distribution of GPR55 was analyzed. Due to the lack of GPR55 specific antibodies, we attempted to generate GPR55-specific monoclonal antibodies in GPR55 knockout mice, however none of these reacted only specifically to the native protein. As alternatives to antibodies, GPR55 mRNA levels were quantified using quantitative polymerase chain reaction (qPCR) and in situ hybridization. The GPR55 knockout mice on the C57BL/6 mouse background failed to generate an autoimmune response during EAE in an initial experiment suggesting that GPR55 controls immune function. Disease was variable in the C57BL/6 mice and EAE was induced in the GPR55 knockout mice on the ABH background and animals developed spasticity. VSN16R is a drug that has shown to inhibit experimental spasticity and binds specifically to GPR55, without the typical side effects associated with cannabis. This compound was found to be an allosteric modulator of GPR55. Animals were treated with VSN16R however the anti-spastic effect remained in the GPR55 knockout mice. Hence, the effect of VSN16R is not mediated by GPR55 in EAE and a novel target needs to be identified.

G蛋白偶聯雌激素受體（GPER，又名GPR30）乃最近於各種動物包括小鼠、大鼠、人類及斑馬魚中發現之新型跨膜雌激素受體。 GPER表達於脂肪組織及多種器官之中，其已被證明能與雌激素結合並介導各式快速反應及基因轉錄。針對GPER於成脂作用中角色之研究將達致對雌激素作用之更全面了解，且GPER亦有望成為治療肥胖症之一種新型標靶。 / 脂肪發育調控乃一複雜且精妙之排程，而雌激素已被證明能抑制脂肪形成，是故雌激素替代療法可舒減絶經後婦女之脂肪代謝問題。此項研究發現GPER於小鼠腹部脂肪組織及小鼠前脂肪細胞系3T3-L1中均有表達，且其信使RNA量於受誘導之3T3-L1成脂作用中錄得上調。 / 3T3-L1細胞分化作用會被名為G1之特異性GPER激動劑阻撓於克隆擴增階段（MCE），此即表明GPER有參與成脂調控之可能。通過油紅O染色發現，受G1處理之3T3-L1細胞於分化後所產生之油滴量實比其對照組為低，但此一效果能被特異性GPER小干擾RNA預處理抹除。另外，本研究以流式細胞儀及西方墨點法對細胞週期及細胞週期因子進行分析後，認為激活GPER能觸發對G1期細胞週期停滯之抑制。另一方面，受G1處理並分化中之3T3-L1細胞出現蛋白激酶B磷酸化效應，意味雌激素與GPER結合對成脂作用有雙向調節之可能性。 / 總而言之，本研究結果斷定GPER能介導雌激素對脂肪組織發育之影響，並為成脂作用之負調節因子，故此，一系列成果將有助肥胖症藥物之研發。 / A novel transmembrane estrogen receptor, G-protein coupled estrogen receptor (GPER, also known as GPR30), is recently identified in various animals including mouse, rat, human and zebrafish. GPER is expressed in many organs including fatty tissues, and has been demonstrated to mediate various rapid responses and transcriptional events upon estrogen binding. The study on the role of GPER in adipogenesis would lead to a more comprehensive understanding of estrogenic actions, with the view of identifying novel therapeutic targets for the treatment of obesity. / Regulation of adipose development is a complex and subtly orchestrated process. Estrogen has been shown to inhibit adipogenesis. Estrogen replacement therapy therefore affects fat metabolism in post-menopausal women. In this study, GPER is identified in mouse abdominal fatty tissues; and there is an up-regulation of GPER in the mouse preadipocyte cell line 3T3-L1 during induced adipogenesis. / Differentiation of 3T3-L1 cells is perturbed by the selective GPER agonist G1 at mitotic clonal expansion (MCE), indicating a possible involvement of GPER in the regulation of adipogenesis. By means of Oil-Red-O staining, the production of oil droplets in the G1-treated, differentiated 3T3-L1 cells is shown to be lower than the untreated control; and such effect is reversed by a specific siRNA knockdown of GPER. FACS analysis and Western blot analysis of cell cycle factors during MCE suggest that GPER activation triggers an inhibition of cell cycle arrest at the G1 stage. On the other hand, phosphorylation of Akt in G1-treated differentiating cells implies a possibility of bi-directional estrogenic regulation of adipogenesis via GPER. / To conclude, it is postulated that GPER mediates estrogenic actions in adipose tissues as a negative regulator of adipogenesis. These results provide insights into the development of therapeutic agents for the treatment of human obesity. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Yuen, Man Leuk. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 144-166). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract (English version) --- p.I / Abstract (Chinese version) --- p.III / Acknowledgement --- p.V / Table of Contents --- p.VII / List of Abbreviations --- p.XI / List of Tables --- p.XII / List of Figures --- p.XIII / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1. --- Obesity and adipose tissue --- p.1 / Chapter 1.1.1. --- Obesity --- p.1 / Chapter 1.1.2. --- Fat deposition --- p.3 / Chapter 1.1.3. --- Origin and development of white adipose tissue --- p.5 / Chapter 1.2. --- Adipogenesis --- p.7 / Chapter 1.2.1. --- Origins of white adipocytes --- p.7 / Chapter 1.2.2. --- Signals for adipogenesis --- p.10 / Chapter 1.2.3. --- Regulation of gene expression during adipogenesis --- p.12 / Chapter 1.2.4. --- Common adipose cell lines --- p.16 / Chapter 1.2.5. --- Mechanism of in vitro adipogenesis --- p.21 / Chapter 1.2.5.1. --- Growth arrest --- p.23 / Chapter 1.2.5.2. --- Mitotic clonal expansion --- p.23 / Chapter 1.2.5.3. --- Early and terminal differentiation --- p.24 / Chapter 1.3. --- Estrogen and adipogenesis --- p.28 / Chapter 1.4. --- G-protein coupled estrogen receptor-1 --- p.33 / Chapter 1.4.1. --- General introduction of GPER --- p.33 / Chapter 1.4.2. --- Ligands of GPER --- p.36 / Chapter 1.4.3. --- Cellular signaling of GPER --- p.38 / Chapter 1.4.4. --- Metabolic actions of GPER: A brief introduction --- p.43 / Chapter 1.4.5. --- Metabolic actions of GPER on obesity and glucose metabolism --- p.48 / Chapter 1.4.6. --- Study objectives --- p.53 / Chapter Chapter 2: --- Expression profiles and cellular localization of Gper/GPER in mouse adipose, 3T3-L1 preadipocytes and 3T3-L1 mature adipocytes --- p.54 / Chapter 2.1. --- Introduction --- p.54 / Chapter 2.1.1. --- Expression and functional roles of GPER in adipose. --- p.55 / Chapter 2.1.2. --- Swiss mouse preadipocytes 3T3-L1 --- p.57 / Chapter 2.1.3. --- Study objectives --- p.57 / Chapter 2.2. --- Materials and Methods --- p.59 / Chapter 2.2.1. --- Reagents --- p.59 / Chapter 2.2.2. --- Animal tissues --- p.59 / Chapter 2.2.3. --- Cell culture --- p.60 / Chapter 2.2.4. --- Reverse transcription polymerase chain reaction (RT-PCR) --- p.62 / Chapter 2.2.5. --- Quantitative real-time RT-PCR (qRT-PCR) --- p.66 / Chapter 2.2.6. --- SDS-PAGE and Western blot analysis --- p.68 / Chapter 2.2.7. --- Immunofluorescence assay --- p.69 / Chapter 2.2.8. --- Statistical analysis --- p.70 / Chapter 2.3. --- Results --- p.71 / Chapter 2.3.1. --- Expression of Gper/GPER in mouse visceral adipose tissues --- p.72 / Chapter 2.3.2. --- Expression profiles of Gper/GPER in undifferentiated 3T3-L1 preadipocytes and differentiated 3T3-L1 adipocytes --- p.73 / Chapter 2.3.3. --- Cellular localization of GPER in undifferentiated 3T3-L1 preadipocytes and differentiated 3T3-L1 adipocytes --- p.75 / Chapter 2.4. --- Discussion --- p.76 / Chapter Chapter 3: --- Rapid cellular responses induced by GPER activation in 3T3-L1 preadipocytes --- p.78 / Chapter 3.1. --- Introduction --- p.78 / Chapter 3.1.1. --- Rapid cellular response of estrogen via GPER --- p.79 / Chapter 3.1.2. --- Study objectives --- p.81 / Chapter 3.2. --- Materials and Methods --- p.82 / Chapter 3.2.1. --- Reagents --- p.82 / Chapter 3.2.2. --- Cell culture --- p.82 / Chapter 3.2.3. --- SDS-PAGE and Western blot analysis --- p.83 / Chapter 3.2.4. --- Statistical analysis --- p.84 / Chapter 3.3. --- Results --- p.86 / Chapter 3.3.1. --- Phosphorylation of p44/42 MAPK after time-dependent activation of GPER by ICI182,780 and G1 --- p.87 / Chapter 3.3.2. --- Phosphorylation of p44/42 MAPK after dose-dependent activation of GPER by a combination of chemical agents --- p.88 / Chapter 3.4. --- Discussion --- p.89 / Chapter Chapter 4: --- GPER activation on cell viability of 3T3-L1 preadipocytes --- p.90 / Chapter 4.1. --- Introduction --- p.90 / Chapter 4.1.1. --- Cell proliferation mediated by GPER --- p.90 / Chapter 4.1.2. --- Study objectives --- p.92 / Chapter 4.2. --- Materials and Methods --- p.93 / Chapter 4.2.1. --- Reagents --- p.93 / Chapter 4.2.2. --- Cell culture --- p.93 / Chapter 4.2.3. --- MTT assay for cell viability --- p.94 / Chapter 4.2.4. --- Statistical analysis --- p.95 / Chapter 4.3. --- Results --- p.96 / Chapter 4.3.1. --- Cell viability of 3T3-L1 after dose-dependent activation of GPER by 17β-estradiol, ICI182,780 and G1 --- p.97 / Chapter 4.4. --- Discussion --- p.99 / Chapter Chapter 5: --- GPER-mediated estrogenic action on lipid accumulation in the mature 3T3-L1 adipocytes --- p.101 / Chapter 5.1. --- Introduction --- p.101 / Chapter 5.1.1. --- Induction of differentiation in Swiss mouse preadipocyte 3T3-L1 --- p.101 / Chapter 5.1.2. --- Study objectives --- p.102 / Chapter 5.2. --- Materials and Methods --- p.103 / Chapter 5.2.1. --- Reagents --- p.103 / Chapter 5.2.2. --- Cell culture --- p.103 / Chapter 5.2.3. --- Oil-Red-O staining and measurement of absorbance --- p.105 / Chapter 5.2.4. --- Knockdown of Gper/GPER by siRNA --- p.107 / Chapter 5.2.5. --- Reverse transcription polymerase chain reaction (RT-PCR) --- p.110 / Chapter 5.2.6. --- SDS-PAGE and Western blot analysis --- p.110 / Chapter 5.2.7. --- Statistical analysis --- p.110 / Chapter 5.3. --- Results --- p.112 / Chapter 5.3.1. --- GPER activation on 3T3-L1 differentiation --- p.114 / Chapter 5.3.2. --- Knockdown of Gper/GPER in Swiss mouse preadipocyte 3T3-L1 --- p.114 / Chapter 5.3.3. --- Phosphorylation of p44/42 MAPK in Gper/GPER-knockdown 3T3-L1 after time-dependent activation of GPER by G1 --- p.117 / Chapter 5.3.4. --- Action of drugs on differentiation of Gper/GPER-knockdown 3T3-L1 --- p.117 / Chapter 5.4. --- Discussion --- p.118 / Chapter Chapter 6: --- Role of GPER in regulating cell cycle progression during mitotic clonal expansion (MCE) stage in adipogenesis of 3T3-L1 --- p.120 / Chapter 6.1. --- Introduction --- p.120 / Chapter 6.1.1. --- Differentiation stages of Swiss mouse preadipocyte 3T3-L1 --- p.121 / Chapter 6.1.2. --- Apoptosis and cell cycle progression --- p.122 / Chapter 6.1.3. --- Study objectives --- p.126 / Chapter 6.2. --- Materials and Methods --- p.127 / Chapter 6.2.1. --- Reagents --- p.127 / Chapter 6.2.2. --- Cell culture --- p.127 / Chapter 6.2.3. --- Oil-Red-O staining and measurement of absorbance --- p.129 / Chapter 6.2.4. --- Trypan blue exclusion assay for cell viability determination --- p.129 / Chapter 6.2.5. --- SDS-PAGE and Western blot analysis --- p.131 / Chapter 6.2.6. --- Flow cytometry for analysis of cell cycle progression --- p.132 / Chapter 6.2.7. --- Statistical analysis --- p.133 / Chapter 6.3. --- Results --- p.134 / Chapter 6.3.1. --- Temporal effect of GPER activation on differentiation progress of Swiss mouse preadipocyte 3T3-L1 --- p.137 / Chapter 6.3.2. --- Effect of GPER activation on cell viability during adipogenesis --- p.139 / Chapter 6.3.3. --- Effect of GPER activation on apoptosis during adipogenesis --- p.139 / Chapter 6.3.4. --- Effect of GPER activation on cell cycle distribution during induced adipogenesis --- p.140 / Chapter 6.3.5. --- Effect of GPER activation on expression of cell cycle markers during induced adipogenesis --- p.142 / Chapter 6.3.6. --- Activation of PI3K/Akt pathway by GPER stimulation during induced adipogenesis --- p.143 / Chapter 6.4. --- Discussion --- p.144 / Chapter Chapter 7: --- Conclusions and Future Perspectives --- p.148 / References --- p.155

Ectopic and over-expression of G protein-coupled receptor (GPCR) have been reported to induce tumor formation. Mas protein is a member of GPCR family and was originally isolated from human epidermoid carcinoma. It was demonstrated that mas mRNA was abundantly expressed in human and rat brains by in situ hybridization and RNase protection assays. However, cellular mechanism that leads to such tumorigenic transformation is still an open question. / In order to identify the cellular mechanism of mas-induced tumor formation, a full-length mas cDNA was cloned into a mammalian expression vector pFRSV with dihydrofolate reductase gene as a selection marker. Detailed analyses of mas-transfected cell lines by Southern blot, Northern blot and tumorigenicity assay indicated that tumorigenicity of mas-transfected cells depended on the sites of chromosomal integration and the levels of mas expression. These results suggest that overexpression of mas is not sufficient to induce tumor formation. In line with the ability of mas-transfected cells Mc0M80 to form solid tumor in nude mice, MTT cell proliferation assay indicated that the mas-transfected cells Mc0M80 proliferated faster than vector-transfected cells. Moreover, mas-transfected cells Mc0M80 exhibited significantly increased anchorage-independent growth. Furthermore, mas-transfected cells Mc0M80 showed higher percentage cells in G2/M phase but lower in S-phase in comparison with vector-transfected cells. / Interestingly, Southern blot analysis of individual xenografted tumor tissue indicated that tumor was composed of cells not only derived from injected mas-transfected CHO cells but also cells from mouse tissues. The presence of mouse stromal cells in the tumor was confirmed by immunohistochemistry and in situ hybridization. Previously our laboratory had identified some up- and down-regulated genes in mas-transfected cells by fluorescent differential display (FluoroDD). Northern blot showed that these differential expressed genes were up- or down-regulated in mas-transfected cells and tumor samples, which might play an important role in cancerous growth. / Taken together, these results suggest that over-expression of GPCR mas up-regulated tumor-related genes, resulting in promoting excessive cell growth and tumorigenic transformation. In addition, when the tumor mass formed they secreted some growth factor(s) which altered the migration of mouse stromal cells into tumor mass. The interactions of transformed cells and stromal cells further aggravate the tumorigenicity process. / To complement our fluorescent differential display study and to compare changes of gene expression when transformed cells were exposed to the microenvironment in nude mice, protein expression profiles of mas over-expressing cells as well as tumor tissues were analyzed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and mass spectrometry. The 2D-PAGE analysis showed that a similar but distinct protein expression profiles in mas-transfected cells and in mas-induced tumor. Mass spectrometry analysis identified several cancerous growth-related proteins and they are involved in processes such as cell signaling, energy metabolism, transcription and translation and cytoskeleton organization. / Lin Wenzhen. / "December 2005." / Adviser: Cheung Wing Tai. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6381. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 222-240). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Bikkavilli Rama Kamesh. / "August 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 212-223) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The apelin system is an evolving transmitter system consisting of the G protein coupled apelin receptor and two endogenous peptide ligands, apelin and elabela. It is implicated as a potential therapeutic for a number of diseases; however, the endogenous peptides are limited by half-life and bioavailability. This study aims to identify and pharmacologically characterise apelin agonists in vitro and in vivo and to evaluate their therapeutic potential in pulmonary arterial hypertension as a model disease. CMF-019 was identified as the first G protein biased apelin agonist. To date, suitable small molecule apelin agonists as experimental tool compounds have been limited and CMF-019 represents an important advance. CMF-019 was active in vivo, producing an increase in cardiac contractility and vasodilatation, similar to apelin. These effects were achieved without receptor desensitisation, supporting the remarkable G protein bias observed in vitro. Furthermore, it was disease-modifying in vitro in an endothelial cell apoptosis assay but despite this, did not prevent pulmonary arterial hypertension in a monocrotaline rat model of the disease. An apelin mimetic peptide possessing an unnatural amino acid, MM202, conjugated chemically via a polyethylene glycol linker to an anti-serum domain antibody (AlbudAb) was also characterised. The product MM202-AlbudAb represents the first time an AlbudAb has been conjugated chemically to an unnatural peptide mimetic, providing protection from proteolysis and glomerular filtration. Importantly, it retained binding to albumin and demonstrated in vitro and in vivo activity at the apelin receptor. In conclusion, this thesis has identified and pharmacologically characterised two novel apelin agonists that possess significant advantages over the endogenous peptides. CMF-019 is suitable as an experimental tool compound and, as the first G protein biased small molecule, provides a starting point for more suitable therapeutics. In addition, MM202-AlbudAb proves that unnatural peptides can be conjugated to AlbudAb, supporting use of this technology in other small-peptide ligand transmitter systems.

Medulloblastoma is the most common malignant brain tumor in children. Genetic profiling has identified four principle tumor subgroups; each subgroup is characterized by different initiating mutations, genetic and clinical profiles, and prognoses. The two most well-defined subgroups are caused by overactive signaling in the WNT and SHH mitogenic pathways; less is known about Groups 3 and 4 medulloblastomas. Identification of tumor subgroup using molecular classification is poised to become an important component of the medulloblastoma diagnosis and staging and will likely guide therapeutic options. G-protein coupled receptors (GPCR) possess characteristics that make them ideal targets for molecular imaging and therapeutics. While expression patterns of many proteins in human medulloblastoma subgroups have been discerned, the expression pattern of GPCRs in medulloblastoma has not been investigated. We have found that clusters of medulloblastoma tumors arise based solely on differential GPCR expression patterns. Further, two of these clusters correspond with high fidelity to the WNT and SHH subgroups. Distinct over-expressed GPCRs emerge; for example, LGR5 and GPR64 are significantly and uniquely over-expressed in the WNT subgroup of tumors, while PTGER4 is over-expressed in the SHH subgroup. Uniquely under-expressed GPCRs were also observed. Our results identify GPCRs with potential to act as imaging and therapeutic targets; elucidating tumorigenic mechanisms is a secondary benefit to identifying differential GPCR expression patterns in medulloblastoma tumors. Current imaging for diagnosis, staging, and measuring response to therapy for medulloblastoma patients relies heavily on MRI; single photon emission tomography (SPECT) using 111In-DTPA-Octreotide targeting the somatostatin type 2 receptor (SSTR2) is also available. Positron emission tomography (PET) affords a more sensitive and specific imaging modality than SPECT; however, the most common tracer 18FDG, is of limited usefulness for the delineation of brain tumors. Smoothened (SMO) is a GPCR that is overexpressed in a subset of medulloblastoma; we hypothesized that SMO overexpression could be exploited as a specific PET target in these tumors. Genentech generously provided the synthetically-derived small-molecule SMO ligand, GDC-0449, for use as the lead compound for development of a PET tracer. GDC-0449 has already been demonstrated to localize in brain tumors and has Cl- atoms incorporated in positions that are predicted to readily exchange with fluorine-18 to generate a fluorinated analog of the compound. We have successfully fluorinated GDC-0449, with very high radiochemical purity. Binding assays reveal affinities of the fluorinated analog of GDC-0449 for SMO to be comparable to precursor GDC-0449, and biodistribution experiments demonstrate accumulation of the fluorinated compound in tumors. The fluorinated analog of GDC-0449 holds promise as a novel PET imaging agent in medulloblastoma, providing highly specific and sensitive imaging for use in diagnosis, staging and measurement of response-to-treatment.