Hemoglobin expression in alveolar type II cells.
Newton-DA; Rao-M; Baatz-JE
Proc Am Thorac Soc 2005 May; 2(Abstracts):A227
Hemoglobin gene expression has been previously reported in activated macrophages from adult mice, and recent studies indicate that alveolar epithelial cells can be derived from hematopoietic stem cells. Our laboratory has now produced strong preliminary evidence that hemoglobin is expressed by alveolar type II (ATII) cells, important stem cells of the pulmonary epithelium and producers of surfactant. RT-PCR was used to measure the expression of nearly all possible transcripts from both the alpha globin (HBA) and beta globin (HBB) gene clusters in several human and rodent ATII cells. Surprisingly, PCR products of the predicted sizes were obtained in human A549 cells (HBA and HBB, the two major globins expressed by adult erythroid cells), mouse MLE-15 cells (HBA ortholog), and primary ATII cells isolated from normal rat and mouse lungs (HBA and HBB orthologs). As controls, these cells also demonstrated expression of genes characteristic of pulmonary epithelial cells (e.g., surfactant proteins), but not other erythroid-specific genes like the erythrocyte anion-exchanger (band 3 protein). PCR products were subjected to DNA sequencing to verify that they were indeed the result of specific amplification of globin gene cDNAs. These cells also expressed hemoglobin protein subunits as determined by probing Western blots with three different anti-hemoglobin antibodies. In addition, tandem mass spectrometry sequencing was used to verify the expression of both alpha and beta globin polypeptides in rat primary ATII cells. The function(s) of hemoglobin expression by cells of the pulmonary epithelium will be determined by future studies, but this novel finding could potentially have enormous implications on the physiology and pathology of the lung.
Laboratory-animals; Animals; Animal-studies; Surfactants; Genes; Mass-spectrometry; Lung; Physiology; Pathology; Cell-cultures
Abstract; Conference/Symposia Proceedings
Issue of Publication
Proceedings of the American Thoracic Society. 2005 ATS International Conference, May 20-25, 2005, San Diego, California