ANGIOTENSIN REGULATION OF GENE EXPRESSION

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DESCRIPTION: (Adapted from the application) Chronic stimulation of Ang II receptors effects proliferation, growth and survival of cells in cardiovascular, neural, endocrine and kidney tissues. The molecular mechanism by which Ang II accesses genetic programming for the cell growth and proliferation are unknown. Their elucidation, essential for understanding physiological and pathophysiological effects of AII in neural, endocrine and cardiovascular system, is the central goal of this proposal. The principal investigator (PI's) studies have revealed a new signaling mechanism that activates cell growth and proliferation of neural, glial and smooth muscle lineages. This pathway is initiated by an induction of fibroblast growth factors (FGF-2) and FGF receptor-1 (FGFR-1) genes with the consequent accumulation of FGF-2 and FGFR-1 proteins directly into the cell nucleus. Nuclear FGF-2 and FGFR-1 activate through a feed-forward mechanism transcription of other genes and induce cell growth and entry into the cell cycle. The PI has shown that this new intracrine-nuclear FGF-2/FGFR-1 pathway is activated by Ang II receptor in adrenal medullary cells, astrocytes and smooth muscle cells. The molecular mechanisms through which Ang II activates the initial steps in FGF-2-FGFR-1 pathway is the focus of this proposal. The PI indicates that Ang II activates FGF-2 gene by inducing a multiple-protein complex with an Ang II responsive region (Ang IIRR, -555/-512 BP) of FGF-2 promotor that also mediates FGF-2 gene activation by soluble cytokines and reduced cell contact. Ang IIRR is separate from cAMP/PKC responsive sequences (-625/-556 BP), contains unique protein-binding sequences and interacts with new transcriptional factors. The PI's findings also indicate that the FGF-2 and FGFR-1 proteins accumulating in the cell nucleus, stimulate the Ang IIRR-associated transactivating complex and thereby serve to enhance Ang II activation of FGF-2 gene. Thus, based on all of this information, the central aim of this project is to identify nuclear transduction mechanism through with Ang II activates the FGF-2 gene and the type of Ang II receptors that mediate this activation. As a model, the PI will use cultured, non-transformed bovine adrenal medullary cells (BAMC). The aims are as follows: 1) To identify and clone adrenal medullary trans-acting factors that form multiple protein complex with Ang IIRR and to determine the role of AT2 and AT1 in activation of FGF-2 gene promotor, 2)To further determine the structure of Ang IIRR complex and the functions of its cloned protein components, and 3) To determine the role of nuclear FGF-2 and FGFR-1 proteins in Ang II activation of FGF-2 promotor and of Ang IIRR complex.