Adaptive responses to physiological stressors like hypoglycemia, hypotension, and exposure to cold are mediated by changes in neuroendocrine activity. The relationships between these environmental stimuli and cell responsiveness at the molecular level are central to an understanding of biological adaption throughout development and to mechanisms of phenotypic expression in maturity. Many of these relationships require tissue- specific gene control in which factors initiating transcription are critical determinants of physiological function or of choices made during development. Indeed, in this context, the next logical step in elucidating mechanisms of transcription control requires identification and isolation of factors which bind to regulatory sequences of DNA (i.e. at promoters or enhancer sites). Dr. La Gamma has identified a transsynaptic mechanism through which co-localized preproenkephalin and catecholamine transmitter genes (tyrosine hydroxylase) are related differentially in the rat adrenal medulla. Dr. LaGamma proposes to conduct experiments to describe an approach to identify and characterize putative regulatory molecules in this native eukaryotic tissue. He will employ transcription "run-off" assays, the DNA "shift" assay, and the exoIII protection assay to identify transsynaptic regulatory proteins that alter expression of enkephalin and tyrosine hydroxylase genes. Future work is planned to partially purify adrenomedullary nuclear proteins in conditions where preproenkephalin gene transcription is altered. Once purified and characterized, future work may lead to the development of synthetic molecules in this and other systems that can read large scale sequences of DNA and produce new research tools for use in molecular biology, diagnosis of disease, and even new chemotherapeutic strategies. In this way, the role of environmental stimuli on nervous system function can begin to be explained or modified at the cellular and molecular levels.
