<p>The human endometrium undergoes dramatic changes in morphology and function during the menstrual cycle. Recurrent angiogenesis (the formation of new blood vessels) is of utmost importance for oxygen supply and nourishment of the rapidly growing endometrial tissue. </p><p>The importance of some growth factors known to stimulate new blood vessel formation both in vivo and in vitro in non-uterine tissues, for endometrial angiogenesis, was studied. Further, the possible relationship between the patterns of expression of some angiogenic growth factors and bleeding disturbances during the use of a progestin-only intrauterine contraceptive device was analyzed. Different ways of determining changes in the endometrial vascular density during the menstrual cycle were also evaluated. </p><p>The expression of the angiogenic growth factors vascular endothelial growth factors (VEGF) A, B, C, and D, fibroblast growth factor 2 (FGF-2), and epidermal growth factor (EGF) and their receptors was analyzed using immunohistochemistry.</p><p>VEGF-A, -B and -C, FGF-2 and EGF and their receptors were all found to be expressed in normal human endometrium, especially in and/or around blood vessels, supporting the hypothesis that these peptides most probably contribute to the regulation of angiogenesis and blood vessel function in normal human endometrium.</p><p>There were differences in expression of some of the studied ligands and receptors in endometrium from users of an LNG-IUS with and without bleeding disturbances. We conclude that changes in the expression of these growth factors and receptors might be involved in the formation of fragile and dysfunctional blood vessels that subsequently give rise to bleeding disturbances.</p><p>The three different methods that were applied for calculating endometrial blood vessel density showed similar results and none of them indicated any significant changes during the menstrual cycle. Angiogenesis thus seems to occur mainly by blood vessel elongation and the angiogenic activity is probably related to changes in endometrial thickness and coiling of the spiral arteries.</p>

<p>Angiogenesis is defined as the formation of new capillary blood vessels from pre-existing ones. This process involves several steps including: migration, proliferation and differentiation of endothelial cells into blood vessels. Angiogenesis is initiated by binding of specific growth factors, such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF), to their cell surface receptors. Shb is a ubiquitously expressed adaptor protein with the ability to bind several tyrosine kinase receptors. My aim has been to identify the role of Shb in FGF- and VEGF-signalling in endothelial cells. Shb was found to be phosphorylated in a Src-dependent manner upon both FGF- and VEGF-stimulation. This was confirmed using fibroblasts overexpressing temperature sensitive v-Src. Furthermore, Shb-induced cell spreading on collagen of immortalised brain endothelial (IBE) cells was also Src-dependent. FGF stimulation led to a direct association between Shb and FAK, which was mediated by the phosphotyrosine binding domain of Shb. IBE cells overexpressing wild-type or R522K Shb (inactive SH2 domain) displayed increased FAK activation on collagen.</p><p>The SH2-domain of Shb was found to bind to tyrosine 1175 in the VEGFR-2 in a phosphotyrosine dependent manner using PAE cells expressing VEGFR-2. Furthermore, by use of siRNA, Shb knock-down experiments revealed that Shb regulates FAK activity, cellular migration and stress fiber formation in response to VEGF stimulation of VEGFR-2. In summary, Shb binds to both FGFR-1 and VEGFR-2 and regulates the activity of FAK and thereby stress fiber formation and cellular migration, which are necessary for formation of new blood vessels. IBE cells with an inactive SH2 domain of Shb displayed disorganised formation of tubular structures in the tube formation assay, while overexpression of wild-type Shb led to accelerated tubular morphogenesis.</p><p>Taken together, my data show that the adaptor protein Shb plays an important role in the process angiogenesis, in response to angiogenic tyrosine kinase receptors, by interacting with FAK and regulating spreading, stress fiber formation and cellular migration.</p>

The human endometrium undergoes dramatic changes in morphology and function during the menstrual cycle. Recurrent angiogenesis (the formation of new blood vessels) is of utmost importance for oxygen supply and nourishment of the rapidly growing endometrial tissue. The importance of some growth factors known to stimulate new blood vessel formation both in vivo and in vitro in non-uterine tissues, for endometrial angiogenesis, was studied. Further, the possible relationship between the patterns of expression of some angiogenic growth factors and bleeding disturbances during the use of a progestin-only intrauterine contraceptive device was analyzed. Different ways of determining changes in the endometrial vascular density during the menstrual cycle were also evaluated. The expression of the angiogenic growth factors vascular endothelial growth factors (VEGF) A, B, C, and D, fibroblast growth factor 2 (FGF-2), and epidermal growth factor (EGF) and their receptors was analyzed using immunohistochemistry. VEGF-A, -B and -C, FGF-2 and EGF and their receptors were all found to be expressed in normal human endometrium, especially in and/or around blood vessels, supporting the hypothesis that these peptides most probably contribute to the regulation of angiogenesis and blood vessel function in normal human endometrium. There were differences in expression of some of the studied ligands and receptors in endometrium from users of an LNG-IUS with and without bleeding disturbances. We conclude that changes in the expression of these growth factors and receptors might be involved in the formation of fragile and dysfunctional blood vessels that subsequently give rise to bleeding disturbances. The three different methods that were applied for calculating endometrial blood vessel density showed similar results and none of them indicated any significant changes during the menstrual cycle. Angiogenesis thus seems to occur mainly by blood vessel elongation and the angiogenic activity is probably related to changes in endometrial thickness and coiling of the spiral arteries.

Angiogenesis is defined as the formation of new capillary blood vessels from pre-existing ones. This process involves several steps including: migration, proliferation and differentiation of endothelial cells into blood vessels. Angiogenesis is initiated by binding of specific growth factors, such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF), to their cell surface receptors. Shb is a ubiquitously expressed adaptor protein with the ability to bind several tyrosine kinase receptors. My aim has been to identify the role of Shb in FGF- and VEGF-signalling in endothelial cells. Shb was found to be phosphorylated in a Src-dependent manner upon both FGF- and VEGF-stimulation. This was confirmed using fibroblasts overexpressing temperature sensitive v-Src. Furthermore, Shb-induced cell spreading on collagen of immortalised brain endothelial (IBE) cells was also Src-dependent. FGF stimulation led to a direct association between Shb and FAK, which was mediated by the phosphotyrosine binding domain of Shb. IBE cells overexpressing wild-type or R522K Shb (inactive SH2 domain) displayed increased FAK activation on collagen. The SH2-domain of Shb was found to bind to tyrosine 1175 in the VEGFR-2 in a phosphotyrosine dependent manner using PAE cells expressing VEGFR-2. Furthermore, by use of siRNA, Shb knock-down experiments revealed that Shb regulates FAK activity, cellular migration and stress fiber formation in response to VEGF stimulation of VEGFR-2. In summary, Shb binds to both FGFR-1 and VEGFR-2 and regulates the activity of FAK and thereby stress fiber formation and cellular migration, which are necessary for formation of new blood vessels. IBE cells with an inactive SH2 domain of Shb displayed disorganised formation of tubular structures in the tube formation assay, while overexpression of wild-type Shb led to accelerated tubular morphogenesis. Taken together, my data show that the adaptor protein Shb plays an important role in the process angiogenesis, in response to angiogenic tyrosine kinase receptors, by interacting with FAK and regulating spreading, stress fiber formation and cellular migration.