Regulation of MMP-TIMP extracellular matrix remodeling system as a result of crosstalk between steroid hormones and MAPK signaling network : lessons from the human endometrium
(2005)
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- In the present PhD thesis, we focused on two main questions: what are the changes of expression levels of certain matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) during the menstrual cycle and what are the molecular mechanisms governing these changes? In the first part of the work, we analyzed by the quantitative method of Real Time PCR, the fluctuations of MMP and TIMP mRNA during the menstrual cycle. Several groups of genes could be distinguished: one comprising MMP-1, -3, -10 and -8, whose expression strongly increases around the menstrual phase of the cycle and one comprising TIMP-1, -2 and -3 with relatively high level of expression throughout all the phases of the cycle. Particularly interesting was the profile of TIMP-3 mRNA expression, showing highest levels during the late secretory phase with a sharp decrease in the mid perimenstrual phase. MMP-7 showed a relatively high level of expression throughout the menstrual cycle with significant up-regulation around the menstrual phase. By using endometrial explants as a model system, we showed the key role of combined estradiol and progesterone in the regulation of MMP and TIMP expression, as they inhibited expression of MMPs, TIMP-1 and TIMP-2 but stimulated that of TIMP-3. To overcome some of the limitations of the explant cultures, we used primary endometrial stromal cells as a model system. This allowed us to reproduce the effects of ovarian steroids and to further investigate the mechanisms of coordinated expression of MMP/TIMP system by using promoter constructs, confocal microscopy and Real Time PCR. First, we determined regions in MMP-1 and TIMP-3 promoters, that are responsible for the differential response to ovarian steroids of these two genes. Secondly, we used Real Time PCR technique and mitogen activated protein kinases (MAPK) inhibitors to analyze the relative contribution of the three main signaling pathways of MAPK network in regulating the IL-1 alpha-induced MMP expression. The most potent inhibitor was U0126, suggesting a primary role of the ERK signaling pathway in IL-1 alpha-dependent expression of MMP-1. Confocal microscopy revealed the ability of IL-1 alpha to also accelerate the exit of the progesterone receptor from the nucleus upon progesterone withdrawal. The same effect was reproduced for glucocorticoid receptor upon dexamethasone withdrawal. U0126 was able to inhibit the nuclear exit of the progesterone receptor suggesting the involvement of ERK signaling pathway. We thus demonstrated the presence of multilevel crosstalk between MAPK pathways and steroid receptors contributing to the overall regulation of MMP and TIMP expression.
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Vassilev, V. (2005). Regulation of MMP-TIMP extracellular matrix remodeling system as a result of crosstalk between steroid hormones and MAPK signaling network : lessons from the human endometrium. https://hdl.handle.net/2078.5/110647