Overexpression of surfactant protein-C mature peptide causes neonatal lethality in transgenic mice

Am J Respir Cell Mol Biol. 2002 Jan;26(1):85-90. doi: 10.1165/ajrcmb.26.1.4686.

Abstract

Surfactant replacement preparations containing either surfactant protein (SP)-B or SP-C significantly improve lung function in surfactant-deficient infants, suggesting that these peptides may be functionally redundant. SP-B is absent and SP-C is greatly diminished in the airspaces of SP-B (-/-) mice, which die of respiratory distress syndrome (RDS) shortly after birth. The goal of this study was to determine if elevated expression of SP-C mature peptide could reverse the neonatal lethality in SP-B (-/-) mice. SP-C peptide (residues 24-57 of mouse SP-C proprotein) with a hemagglutinin epitope (SP-C(24-57)HA) was expressed in type II cells of transgenic mice, with the goal of crossing these animals into the SP-B (-/-) background. Unexpectedly, expression of the SP-C(24-57)HA transgene resulted in delayed/arrested lung development and lethal, neonatal RDS of all transgenic progeny in two independent transgenic lines. In transgenic mice, SP-C(24-57)HA was localized predominantly to the endoplasmic reticulum and Golgi; in contrast, SP-B and SP-C were very difficult to detect in the endoplasmic reticulum of wild-type mice. These results suggest that elevated expression of SP-C(24-57)HA in type II cells resulted in aggregation of SP-C in the early secretory pathway, leading to cytotoxicity and, ultimately, altered lung development.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Western
  • Crosses, Genetic
  • Dose-Response Relationship, Drug
  • Endoplasmic Reticulum / metabolism
  • Epitopes
  • Golgi Apparatus / metabolism
  • Immunohistochemistry
  • Lung / embryology*
  • Lung / growth & development
  • Mice
  • Mice, Transgenic
  • Microscopy, Electron
  • Peptides / chemistry*
  • Phenotype
  • Polymerase Chain Reaction
  • Protein Conformation
  • Proteolipids / biosynthesis*
  • Proteolipids / metabolism
  • Pulmonary Surfactants / biosynthesis*
  • Pulmonary Surfactants / metabolism

Substances

  • Epitopes
  • Peptides
  • Proteolipids
  • Pulmonary Surfactants