Differential regulation of baboon SP-A1 and SP-A2 genes: structural and functional analysis of 5'-flanking DNA.
Surfactant protein (SP) A gene transcription is developmentally regulated and stimulated by hormones and factors that increase intracellular cAMP. The baboon (b) genome contains two highly similar SP-A genes, bSP-A1 and bSP-A2. With the use of a ribonuclease protection assay with gene-specific probes, the two bSP-A genes were found to be differentially regulated during baboon fetal lung development in that expression of the bSP-A2 gene appeared to be induced to a high level at a later time in gestation than that of the bSP-A1 gene. Both the bSP-A1 and bSP-A2 genes were found to be highly responsive to the inductive effects of cAMP in baboon fetal lung explants in culture. By DNase I footprinting and electrophoretic mobility shift assays with bacterially expressed thyroid transcription factor-1 (TTF-1) and type II cell nuclear extracts, three TTF-1 binding elements were identified within the 255-bp region flanking the 5'-end of each bSP-A gene; however, these differed in position and spacing for the two bSP-A genes. To functionally define the genomic regions that are required for cAMP regulation of bSP-A gene expression in type II cells, fusion genes composed of various amounts of 5'-flanking DNA from the bSP-A1 and bSP-A2 genes linked to the human growth hormone structural gene as a reporter were transfected into type II cells in primary culture. We found that 255 bp of 5'-flanking DNA, which contain three TTF-1 binding elements, from bSP-A1 and bSP-A2 genes were sufficient to mediate high basal and cAMP-inducible expression in type II cells. We also observed that there were no obvious differences in the magnitude of the responses of these fusion genes to cAMP treatment.
Li
J
J
Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, Dallas 75235-9038, Texas, USA.
Gao
E
E
Seidner
S R
SR
Mendelson
C R
CR
D000818:Animals; D001483:Base Sequence / Q000235:genetics; D001665:Binding Sites / Q000502:physiology; D003994:Bucladesine / Q000494:pharmacology; D046508:Culture Techniques; D004247:DNA / Q000235:genetics* / Q000502:physiology*; D005333:Fetus / Q000166:cytology / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology*; D016678:Genome; D006801:Humans; D008168:Lung / Q000166:cytology / Q000196:embryology; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D010215:Papio / Q000196:embryology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011510:Proteolipids / Q000235:genetics*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D013329:Structure-Activity Relationship; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000378:metabolism
C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D012333:RNA, Messenger; C445842:SFTPA1 protein, human; C445843:SFTPA2 protein, human; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D003994:Bucladesine; D004247:DNA