THE ROLE OF INSULIN IN HUMAN FETAL LUNG DEVELOPMENT

University Of Iowa, Iowa City IA

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Abstract

DESCRIPTION: (Adapted from the Investigator's Abstract): The hypothesis is that delayed lung development in the fetus of the diabetic woman is related to surfactant-associated protein deficiency caused by high levels of insulin. Aim 1 is to elucidate the signal transduction pathways involved in insulin-mediated inhibition of SP-A and SP-B gene expression. Signal transduction inhibitors, enzyme assays, characterization of signaling intermediates and transfection with dominant negative and constitutively active constructs will be used to test the hypothesis that the PI-3K signal transduction pathway mediates the effects of insulin. Aim 2 is to identify the cis-acting elements in the SP-A and SP-B genes which mediate the inhibitory effects of insulin. Luciferase reporter gene constructs will be used to localize inhibitory insulin response elements in the 5' flanking region of the human SP-A1 and SP-A2 genes. Aim 3 is to identify the transcription factors that interact with the SP-A1 and SP-B insulin response elements. Electrophoretic mobility shift assays will be used to test the hypothesis that HNF-3a and C/EBPa mediate the insulin-induced inhibition of SP-A and SP-B gene expression. Aim 4 is to describe the molecular events (phosphorylation, localization, and/or changes in gene expression) that link signal transduction to transcription factors which interact with the insulin response elements in the SP-A1 and SP-B genes.