Integrins play an essential role in multicellular life by connecting cells to the extracellular matrix. This thesis provides an overview of the distinct types of integrin-containing cell adhesion... Show moreIntegrins play an essential role in multicellular life by connecting cells to the extracellular matrix. This thesis provides an overview of the distinct types of integrin-containing cell adhesion complexes present in epithelial cells. By employing BioID we succesfully characterized the composition of focal adhesions, flat clathrin lattices, and hemidesmosomes. In addition, we investigated the role of different adhesion complexes in (cancer) cell adhesion, migration, polarity, and proliferation and in mechanotransduction. Show less
This thesis describes i) the function of an alternatively spliced coagulation factor in hemostasis, ii) the contribution of coagulation factors on cancer progression, and iii) expands our view... Show moreThis thesis describes i) the function of an alternatively spliced coagulation factor in hemostasis, ii) the contribution of coagulation factors on cancer progression, and iii) expands our view on cancer-associated thrombosis. Inhibition of Tissue Factor (TF) signaling with the antibody (Mab-10H10) resulted in decreased tumor initiating capacity and metastasis in a triple negative breast cancer (TNBC) cell line. Since this is a tumor type that is difficult to treat, and has high relapse-rates, it would be of interest to target TF signaling. Dual treatment of TNBC with conventional chemotherapy and Mab-10H10 could result in a positive treatment strategy as both highly proliferative and cancer stem cells are targeted. Furthermore, we provided a proof-of-principle study to search for novel biomarkers in patients with cancer-associated thrombosis in an unbiased manner. Up till now it is challenging to accurately predict those cancer patients with elevated risk of thrombosis. Furthermore, patients with cancer-associated thrombosis have poorer survival. Expansion of this study to validation cohorts and other tumor types will give insights in the underlying molecular mechanism of cancer-associated thrombosis. Eventually, this will aid a better prediction model to select those cancer patients with high risk of thrombosis and those who might benefit from thromboprophylaxis. Show less
Cells receive mechanical cues from the surrounding extracellular matrix (ECM). This has a strong impact on physiology and pathology in a wide range of biological settings. Integrin receptors couple... Show moreCells receive mechanical cues from the surrounding extracellular matrix (ECM). This has a strong impact on physiology and pathology in a wide range of biological settings. Integrin receptors couple the ECM to the intracellular cytoskeleton across the cell membrane through a dynamic multiprotein adhesion complex and mediate bidirectional force transmission. In this research the mechanism of cellular mechanotransduction and its role in aspects of cancer progression are studied, focusing on integrins and other integrin associated proteins. We find that the integrin expression profile of cells regulates the orientation and dynamics of force transmission at cell-matrix adhesions. Additionally, using a novel method to quantify the abundance of a molecule in a cellular complex, we show that substrate rigidity modulates the association between traction forces and molecular composition of cell-matrix adhesions. Using cell microprinting in 3D ECM scaffolds, we determine the relation between tumor-induced remote ECM network orientation and angiogenesis. Lastly, genes that regulate cancer cell migration, force application, and adhesion dynamics are identified. Overall, the work described in this thesis unravels the role of cellular mechanotransduction in different aspects of cancer progression and reveals how the molecular composition of cell-matrix adhesions relates to traction force generation. Show less
To treat various cardiac diseases, modification of gene expression for the purpose of increased or decreased expression of a particular gene, is regarded as a potential therapy. As a vehicle to... Show moreTo treat various cardiac diseases, modification of gene expression for the purpose of increased or decreased expression of a particular gene, is regarded as a potential therapy. As a vehicle to introduce the gene of choice into the heart cell, virus vectors have given the most promising results. This thesis describes studies that are undertaken to investigate how virus vectors may be used to efficiently target cardiac cells and what the effects of certain genetic interventions are on the (patho)physiology of heart cells. We used lentivirus vectors to study the effects of integrin stimulation in neonatal rat cardiomyocytes on the uptake of macromolecules by these cells and through which pathway integrin stimulation leads to cardiac hypertrophy. Furthermore, the role of gap junctional coupling in the development of arrhythmias and in the cardiac differentiation of mesenchymal stem cells was investigated by modulating the expression of connexin 43 using lentivirus vectors. As adeno-associated virus vectors in particular have shown great potential as vector system to target the heart, we aimed to develop AAV vectors that may be used to specifically target either the cardiomyocytes or fibroblasts in the heart. Show less
De activatie van zowel witte bloedcellen als complement systeem (betrokken bij het immuunsysteem) zijn geassocieerd met atherosclerose (slagaderverkalking). Het proefschrift bestaat uit drie delen;... Show moreDe activatie van zowel witte bloedcellen als complement systeem (betrokken bij het immuunsysteem) zijn geassocieerd met atherosclerose (slagaderverkalking). Het proefschrift bestaat uit drie delen; In deel I laten wij in 3 hoofdstukken zien dat vetten belangrijker zijn dan glucose voor de activatie van de witte bloedcellen en dus meer in staat zijn om een ontstekingsfenomeen op gang te brengen die leidt tot slagaderverkalking. Verder laten wij zien dat pati_nten met familiair verhoogd cholesterol (FH) en familiair verhoogd cholesterol en verhoogde voedingsvetten (triglyceriden) (FGH) na glucose-belasting een blijvende witte bloedcelactivatie hebben in tegenstelling tot gezonde vrijwilligers. Tenslotte werd aangetoond dat het structurele eiwit van de partikels waarin voedingsvetten vanuit de darmen worden vervoerd (apoB48) geassocieerd is met intima media dikte (een marker voor slagaderverkalking) In deel II associ_ren wij in 3 hoofstukken witte bloedcelactivatie met slagaderverkalking. Zo werd bijvoorbeeld aangetoond dat er in de kransslagaders met slagaderverkalking een hogere witte bloedcelactivatiestatus is dan in andere kransslagaders en bloedvaten zonder slagaderverkalking. Verder is de activatie van monocyten (een subgroep van witte bloedcellen) een voorspeller voor toekomstige hart- en vaatziekten. In deel III zijn ook 3 hoofdstukken beschreven met daarin de rol van mannose bindend lectine (MBL) die een van de routes is van complementactivatie (betrokken bij immuniteit; opruimen van lichaamsvreemde stoffen zoals bacteri_n). In hoofdstuk 1 werd beschreven dat mensen die lage MBL-waarden hebben, een minder effici_ntere vetstofwisseling hebben dan mensen met voldoende MBL-waarden. Echter, als we puur naar slagaderverkalking kijken, zien we dat MBL geen invloed heeft op de progressie van krasslagaderverkalking bij mensen met pre-existent krasslagaderverkalking. Show less
The aim of this thesis is to address how integrin-mediated signaling regulates cellular processes that have profound effects on cell morphology, motility, cancer metastasis, and FN fibrillogenesis,... Show moreThe aim of this thesis is to address how integrin-mediated signaling regulates cellular processes that have profound effects on cell morphology, motility, cancer metastasis, and FN fibrillogenesis, and how these findings can be utilized for relevant medical purposes or advancement of drug discovery. Show less
In neonatal rat ventricular cardiomyocytes (NRVCs), we activated integrins by RGD to test whether integrin stimulation produced hypertrophy. Effect of RGD was compared with pro-hypertrophic effects... Show moreIn neonatal rat ventricular cardiomyocytes (NRVCs), we activated integrins by RGD to test whether integrin stimulation produced hypertrophy. Effect of RGD was compared with pro-hypertrophic effects of phenylephrine (chapter 2). Ventricular failure is associated with disturbed collagen turnover. Myocardial collagen turnover can be assessed by plasma PINP, PIIINP, and ICTP representing collagen synthesis (PINP, PIIINP) or degradation (ICTP). We investigated the effects of cardiac resynchronization therapy (CRT) on collagen turnover in patients at baseline and after 6 months of CRT (chapter 3). Monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) and RV failure are associated with MMP activation in RV, we investigated whether NO plays role in RV hypertrophy and failure (chapter 4). In chapter 5 we reviewed novel approaches to treat experimental PAH. We investigated whether MCT-induced PAH and RV failure can be treated with mesenchymal stem cells (MSCs) from donor rats with PAH caused by MCT. At day 14 after MCT, recipient rats were treated with MSCs. In chapters 6,7 the effects of MSCs on pulmonary pathology and RV function were examined. Isolated cardiomyocytes were investigated for PAH-related changes in excitability. In chapter 8 we reported on excitability properties dependent on Kv-channel expression, proposed to play a role in arrhythmias. Show less
Identification of translational and/or post-translational modifications of cardiac proteins after acute myocardial infarction (AMI) or during the progression to congestive heart failure (CHF) is... Show moreIdentification of translational and/or post-translational modifications of cardiac proteins after acute myocardial infarction (AMI) or during the progression to congestive heart failure (CHF) is relevant to gain insight into the pathological mechanisms. Characterization of the release kinetics of these cardiac proteins from the reversibly or irreversibly injured myocardium into the circulation may lead to new diagnostic biomarkers. Although cardiac Troponin I (cTnI) is a well-known biomarker of irreversible myocardial damage in acute myocardial infarction, we demonstrated that the release of cTnI also occurs from viable cardiomyocytes by a stretch-related mechanism, mediated by integrin stimulation. This finding may explain why in several pathological conditions, such as CHF, plasma cTnI levels are elevated in the absence of myocardial necrosis. In addition, we investigated the role of Tenascin-C re-expression during the development of heart failure and the relevance of TNC as a biomarker of ventricular remodeling. In animals with pressure-overload induced ventricle dilatation, TNC gene expression was upregulated, resulting in re-expression of myocardial TNC protein levels and elevated TNC plasma levels, correlating with cardiac function. Plasma TNC levels in patients with CHF declined during cardiac resynchronization therapy. This study indicates that serial plasma TNC levels can be used as a marker of adverse or reverse ventricular remodeling. Show less
The role of the multifunctional cytokine Transforming Growth Factor-beta 1 in cervical carcinoma on the formation of tumor stroma, tumor infiltrate, PAI-1 and alpha v beta 6 is investigated.
The heart is built for life-long uninterrupted function, supporting blood flow through the organism. During life, the organism as well as its organs will become challenged by exogenous and... Show moreThe heart is built for life-long uninterrupted function, supporting blood flow through the organism. During life, the organism as well as its organs will become challenged by exogenous and endogenous stresses that should be coped with. To be able to adapt to stresses such as altered loading conditions, changes in myocardial perfusion and exposure to toxic agents, the heart possesses ample capabilities. This thesis deals with the question how cardiac cells react to different stresses in an attempt to adapt to the new circumstances. The effect of mechanical stress as well as integrin stimulation on cardiac cells was examined and described. Besides we investigated the reaction of cardiac cells to DNA damage caused by either ionizing radiation or UV-irradiation. The studies reported in this thesis confirm that cardiac cells, both myocytes and fibroblasts have the capacity to respond adequately to exogenous stresses. The responses that have been studied in detail demonstrate that these cells possess systems that sense the stress, transmit its message to the cell interior, and alter gene expression, leading to appropriate reactions. Show less
