Acute cardiovascular clinical events such as myocardial infarction and cerebral stroke represent the major cause of death in Western societies. These pathologies are primarily resulting from... Show moreAcute cardiovascular clinical events such as myocardial infarction and cerebral stroke represent the major cause of death in Western societies. These pathologies are primarily resulting from atherosclerosis, a progressive condition characterized by the accumulation of lipids, immune cells, and fibrous elements in large arteries. The pathogenesis of atherosclerosis involves complex interactions between a wide variety of cells, including monocytes, macrophages, neutrophils, and lymphocytes. It is essential to identify novel targets for therapeutic application in order to reduce the residual atherosclerotic cardiovascular disease risk in current and future patients. Recent studies have suggested that members of the protein arginine methyltransferase (PRMT) family can potentially serve as novel therapeutic targets for atherosclerosis because of their regulatory role in inflammation and metabolism. To validate the contribution of PRMTs in the progression of atherosclerosis, in the studies presented in this thesis we have investigated the effect of inhibition of PRMT functionality on atherosclerosis susceptibility in established atherosclerotic mouse models.To address the role of PRMTs in atherosclerosis, we therefore made use of specific PRMT inhibitors, i.e. TC-E 5003 for PRMT1 inhibition, TP-064 for PRMT4 inhibition, and GSK3326595 for PRMT5 inhibition, that thus far have primarily been applied in vivo in the context of cancer treatment. Show less
Invasive lobular carcinoma (ILC) is the second most common type of breast cancer. Hallmarks of ILC include disruption of adherens junctions and hyperactivation of phosphoinositide 3-kinase (PI3K)... Show moreInvasive lobular carcinoma (ILC) is the second most common type of breast cancer. Hallmarks of ILC include disruption of adherens junctions and hyperactivation of phosphoinositide 3-kinase (PI3K)-mTOR signaling. The tumor suppressor PTEN regulates PI3K signaling. We present a preclinical mouse model of ILC metastasis, based on inactivation of the adherens junction protein E-cadherin and the tumor suppressor p53 and surgical excision of primary tumors. In this model, pharmacological mTOR inhibition blocks growth of primary tumors as well as metastatic disease, and this response is partially dependent on the adaptive immune system. Loss of E-cadherin mouse mammary epithelium leads to apoptosis, and PTEN activation alone results in squamous metaplastic mammary tumors, but a combination of these events leads to ILC formation, indicating a causal role of PI3K signaling together with E-cadherin loss in ILC. Combined somatic loss of the adherens junction molecule p120 and p53 in the mouse mammary gland leads to metaplastic mammary tumors, and loss of p120 in breast cancer cell lines promotes anoikis resistance through hypersensitization of growth factor receptor (GFR) signaling. Combined inactivation of E-cadherin, p120 and p53 induces basal-like tumors, with an epithelial-to- mesenchymal-transition (EMT) phenotype, and no ILC formation. Show less
The research in this thesis is aimed at the elucidation of the role of the glucocorticoid receptor (GR) in hippocampal neuroplasticity and functioning. To achieve this, we have developed a novel... Show moreThe research in this thesis is aimed at the elucidation of the role of the glucocorticoid receptor (GR) in hippocampal neuroplasticity and functioning. To achieve this, we have developed a novel method to specifically knockdown GR in a discrete cell population of the mouse brain. In this thesis I report silencing of GR expression selectively in a population of neuronal progenitors and immature neurons of the dentate gyrus, using RNA-interference (RNAi) delivered by a lentiviral vector. Characterization of these cells resulted in the discovery that GR knockdown causes a striking modulation of hippocampal neurogenesis and remodelling of hippocampal circuitry. Functional studies further revealed consequences of GR knockdown for contextual memory performance and behavioural coping strategies during stressful conditions. The results demonstrate the feasibility to apply RNAi in discrete cell populations for study of the action mechanism of glucocorticoids underlying control of neuroplasticity and behaviour. Show less
