MECHANISM OF ACTION OF STEROID HORMONE

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DESCRIPTION: The long-term goal of the investigator's research is to understan the molecular and metabolic events involved in the initiation of glucocorticoi hormone actions, using model systems that will shed light on clinically important hormone effects. The current focus is on the glucocorticoid inhibition of the inducible prostaglandin G/H synthase, cyclooxygenase-2 (Cox-2), which appears to be the critical step in many diverse glucocorticoid actions. Cox-2 is an immediate-early gene, rapidly induced by agents that stimulate growth (growth factors, cytokines, mitogens, and oncogenes), and massively induced by trauma. Its increased expression plays a critical role in many pathologies that include: acute and chronic inflammatory diseases, Alzheimer's disease, cardiovascular disease, and some cancers of the lung, colon and skin. The focus of this proposal is to examine the hypothesis that E4BP4 serves as mediator of glucocorticoid actions on these and/or other genes Specific Aim 1 will study the regulation of the iNOS promoter, which responds to E4BP4, and in the course develop a stably integrated expression system to study E4BP4 actions on the cellular genes. Specific Aim 2 will analyze the Cox-2 promoter and utilize the systems developed under Specific Aim 1 to study actions of E4BP4 on the endogenous Cox-2 gene. Confirmation of the specificity of the effects will be achieved through mutations, competitive inhibitions, an expression of a specific antagonist to E4BP4. In Specific Aim 3, a more global analysis of individual cellular mRNAs and proteins will be performed to further establish the specificity of individual gene responses to glucocorticoids on the one hand, and E4BP4 on the other, by seeking identities in the responses, and by the ability of an E4BP4 antagonist to selectively block the responses of individual genes