Characterization of two baboon surfactant protein A genes

Erwei Gao, Ying Wang, Susan M. Mccormick, Jinxing Li, Steven R. Seidner, Carole R. Mendelson

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

The gene encoding surfactant protein A (SP-A) is expressed in type II pneumonocytes and is developmentally and hormonally regulated in fetal lung tissue. SP-A is encoded by a single-copy gene in rabbits, dogs, rats, and mice. By contrast, the human genome contains two similar genes, hSP-A1 and hSP-A2, which are differentially regulated during development and differentially regulated by adenosine 3',5'-cyclic monophosphate (cAMP) and glucocorticoid treatment of human fetal lung in culture. In the present study, we have isolated and characterized baboon genomic clones containing two highly similar SP-A genes. Restriction mapping of these clones, together with Southern analysis of genomic DNA, indicates that these comprise two distinct baboon SP-A genes. Sequence comparison of DNA upstream of the transcription initiation sites and within the 3'-untranslated regions encoded by exon VI indicates that one of the baboon SP-A genes (bSP-A1) is more similar to hSP-A1, whereas the other (bSP-A2) is more similar to hSP- A2. Primer extension analysis of baboon lung mRNA indicates that both baboon SP-A genes utilize conserved transcription initiation sites. Reverse transcriptase-polymerase chain reaction analysis of RNA isolated from lung tissues of fetal baboons of 160 days gestational age indicates that both bSP-A1 and bSP-A2 are expressed in baboon fetal lung and that mRNA transcripts of bSP-A1 and bSP-A2 genes are primarily comprised of sequences encoded by exons I and III-VI. However, minor transcripts of the bSP-A1 gene containing exon II and exon II plus an extension also were detected. The presence of two SP-A genes in the baboon suggests that duplication of the SP-A gene occurred >26.5 million years ago, before divergence of the baboon lineage from the man-gorilla-chimpanzee clade.

Original languageEnglish (US)
Pages (from-to)L617-L630
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume271
Issue number4 15-4
DOIs
StatePublished - Oct 1996

Keywords

  • baboon
  • primer extension
  • surfactant protein A
  • surfactant protein A1 gene
  • surfactant protein A2 gene

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology

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