The long term goal of this project is to elucidate the developmental and hormonal regulation of the genes for surfactant lipid biosynthesis. Glucocorticoids stimulate phosphatidylcholine (PC) synthesis in late gestation fetal lung. Of the enzymes involved in PC synthesis, fatty- acid synthase (FAS) is the only one whose gene expression is increased by the hormone. Fatty acids are integral components of lipids and hence of surfactant and there is evidence that they also have a role in the activation of the rate limiting enzyme in PC biosynthesis. Enhanced expression of the FAS gene is, therefore, a critical factor in glucocorticoid stimulated surfactant production in fetal lung. The objective of this proposal is to determine how glucocorticoids enhance expression of the FAS gene and to elucidate the importance of FAS in overall surfactant production in fetal lung.
The Specific Aims are to: (1) Identify the sequences in the FAS gene and flanking regions that are responsible for the glucocorticoid effect. A glucocorticoid responsive region of the FAS gene was identified by deletion analysis and reporter gene expression. DNase footprinting, expression of mutated sequences in reporter gene assays, gel shift and supershift assays and Southwestern blotting will be used to further characterize the precise DNA sequences involved in the glucocorticoid effect and to identify transcription factors binding to them. (2) Determine the effect of inhibiting FAS expression and/or activity on glucocorticoid stimulated surfactant phospholipid production. An antisense strategy will be used to inhibit FAS expression and a metabolic inhibitor to suppress its activity in fetal rat lung explants. (3). Determine if glucocorticoids increase FAS expression in fetal type II cells. A deficiency in surfactant leads to the Respiratory Distress Syndrome (RDS) which remains a serious problem in premature infants. The incidence of RDS can be diminished by maternal glucocorticoid administration. To design better treatment strategies for the prevention of RDS, it is imperative to elucidate how the hormone stimulates surfactant production. Because of its pivotal position in surfactant synthesis, it is therefore crucial to elucidate the mechanism by which glucocorticoids regulate FAS expression.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL043320-26
Application #
6530646
Study Section
Human Embryology and Development Subcommittee 1 (HED)
Program Officer
Berberich, Mary Anne
Project Start
1989-09-01
Project End
2004-02-28
Budget Start
2002-03-01
Budget End
2004-02-28
Support Year
26
Fiscal Year
2002
Total Cost
$404,640
Indirect Cost
Name
Yale University
Department
Pediatrics
Type
Schools of Medicine
DUNS #
082359691
City
New Haven
State
CT
Country
United States
Zip Code
06520
Feng, Nan-Hsiung; Lin, Hen-I; Wang, Jinn-Shyan et al. (2005) Differential expression of a V-type ATPase C subunit gene, Atp6v1c2, during culture of rat lung type II pneumocytes. J Biomed Sci 12:899-911
Roberts, Harold R; Escobar, Miguel; Monroe, Dougald M (2004) More information on patients with factor XI deficiency. Anesthesiology 101:1253-4
Gobran, Laurice I; Rooney, Seamus A (2004) Pulmonary surfactant secretion in briefly cultured mouse type II cells. Am J Physiol Lung Cell Mol Physiol 286:L331-6
Homer, Robert J; Zheng, Tao; Chupp, Geoff et al. (2002) Pulmonary type II cell hypertrophy and pulmonary lipoproteinosis are features of chronic IL-13 exposure. Am J Physiol Lung Cell Mol Physiol 283:L52-9
Beneke, S; Rooney, S A (2001) Glucocorticoids regulate expression of the fatty acid synthase gene in fetal rat type II cells. Biochim Biophys Acta 1534:56-63
Gobran, L I; Rooney, S A (2001) Regulation of SP-B and SP-C secretion in rat type II cells in primary culture. Am J Physiol Lung Cell Mol Physiol 281:L1413-9
Lu, Z; Gu, Y; Rooney, S A (2001) Transcriptional regulation of the lung fatty acid synthase gene by glucocorticoid, thyroid hormone and transforming growth factor-beta 1. Biochim Biophys Acta 1532:213-22
Rooney, S A (2001) Regulation of surfactant secretion. Comp Biochem Physiol A Mol Integr Physiol 129:233-43
Isohama, Y; Rooney, S A (2001) Glucocorticoid enhances the response of type II cells from newborn rats to surfactant secretagogues. Biochim Biophys Acta 1531:241-50
Hei, D J; Grass, J; Lin, L et al. (1999) Elimination of cytokine production in stored platelet concentrate aliquots by photochemical treatment with psoralen plus ultraviolet A light. Transfusion 39:239-48

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