Mice lacking CCAAt/enhancer-binding protein-alpha show hyperproliferation of alveolar type II cells and increased surfactant protein mRNAs

• Published in: Cell and tissue research Vol. 306; no. 1; pp. 57 - 63
• Main Authors: Sugahara, K, Iyama, K I, Kimura, T, Sano, K, Darlington, G J, Akiba, T, Takiguchi, M
• Format: Journal Article
• Language: English
• Published: Germany 01.10.2001
• Subjects: Animals; CCAAT-Enhancer-Binding Protein-alpha - deficiency; CCAAT-Enhancer-Binding Protein-alpha - genetics; Cell Division; Immunohistochemistry; In Situ Hybridization; Mice; Mice, Knockout; Proteolipids - genetics; Pulmonary Alveoli - metabolism; Pulmonary Alveoli - pathology; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants - genetics; RNA, Messenger - genetics; RNA, Messenger - metabolism
• ISSN: 0302-766X
• DOI: 10.1007/s004410100420

The lung-specific surfactant proteins (SP) are essential for normal respiratory function. Transcription factors may play an important role in the regulation of surfactant proteins. The CCAAT/enhancer-binding protein (C/EBP) family consists of transcription factors that can stimulate expression of genes in lipid-metabolizing epithelial cells. C/EBPalpha-deficient mice have been shown to exhibit abnormal pulmonary histopathology. Recently, we demonstrated that C/EBP family members are differentially expressed in alveolar type II cell proliferation and in pulmonary fibrosis. In the present study, to investigate whether the C/EBP family would be involved in the regulation of surfactant proteins, we examined the protein expression of SP-A, and SP-C, and mRNA expression of SP-A, SP-B, and SP-C in the lungs from newborn C/EBPalpha-deficient mice. Using immunohistochemistry, we demonstrated that positive cells for SP-C, specific to alveolar type II cells, in the lungs were more abundant in the newborn C/EBPalpha-deficient mice than in control mice, which suggests the hyperproliferation of alveolar type II cells in the lungs of the C/EBPalpha-deficient mice. In situ hybridization analysis revealed that expression of SP-A, SP-B, and SP-C mRNAs were increased in the lungs of newborn C/EBPalpha-deficient mice. Northern blot analysis revealed that surfactant protein mRNAs were also increased. Thus, these results suggest that C/EBPalpha may play a key role in the proliferation of alveolar type II cells and the regulation of genes of surfactant protein.