Project: Research project

Project Details


The objective of this proposal is to elaborate the mechanism by
which glucocorticoids modulate the synthesis of the 35kDa
surfactant associated protein (PSP-A). At first the developmental
profile of PSP-A synthesis under the influence of glucocorticoids
at the protein and RNA level will be studied using an in vivo
system. The effects of various doses of steroid on PSP-A
synthesis will be examined. The steroid effect on PSP-A synthesis
as a function of gender will also be examined to determine
whether the sex of the animal modulates the glucocorticoid effect
on PSP-A synthesis. These studies may provide insight as to why
male fetuses show a higher incidence of respiratory distress
syndrome and respond poorly to glucocorticoid treatment.
Towards these goals newly synthesized PSP-A from control and
dexamethasone-treated animals will be analyzed by two-
dimensional gel electrophoresis. PSP-A primary translation
products of RNA from the same animals will be analyzed
similarly. RNA levels of PSP-A from the two groups will also be
examined directly by Northern blotting using a rat PSP-A cDNA
probe. Subsequently, experiments will be carried out to determine
whether the increased PSP-A synthesis following glucocorticoid
treatment results from an increased number of Type II epithelial
cells synthesizing PSP-A or whether higher amounts of PSP-A
message are produced per Type II cell. Using biochemical
approaches we will address the questions of whether
glucocorticoids modulate PSP-A synthesis by acting directly at
the transcriptional level. Newly synthesized PSP-A mRNA in
isolated nuclei from whole lung tissue will be obtained from
control or dexamethasone treated animals and its rate of
synthesis will be examined by filter hybridization to rat PSP-A
cDNA. The stability of PSP-A mRNA will also be examined by
pulse-chase experiments if this appears to be a factor in the
regulation of PSP-A synthesis. We will also use the morphological
technique of tissue in situ hybridization, to determine directly
whether the glucocorticoid enhanced PSP-A synthesis reflects a
higher number of Type II cells synthesizing PSP-A or increased
accumulation of PSP-A mRNA in Type II cells. The experiments
outlined here taken together will contribute significantly to our
understanding about how glucocorticoids modulate PSP-A
synthesis and accelerate lung maturity.
Effective start/end date12/31/891/31/97


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