Alveolar cell differentiation markers in human lungs.
We describe two apical surface integral membrane glycoproteins which appear to be differentiation markers of the human pulmonary alveolar type 2 cell which has as a major function the production of pulmonary surfactant. These membrane glycoproteins bind the lectin, Maclura pomifera agglutinin and can be found in detergent extract of whole lungs, lung membranes and isolated type 2 cells. One of the MPA binding glycoproteins (MPA-gp330) has an apparent molecular weight of 330 kD and is analogous to a similar membrane glycoprotein found in rat and rabbit type 2 cells. The other glycoprotein (MPA-gp350/390) is an antigen found on the surface of many human cancer cells. In studies of human fetal lung tissue we found that MPA-gp350/390 is expressed before known surfactant functions of the type 2 cell while MPA-gp330 appears later. Neither glycoprotein is influenced by glucocorticoids yet surfactant synthesis is hormone-dependent. These studies demonstrate that pulmonary type 2 cell differentiation is a more complex process than previously appreciated and that differentiation markers are expressed in a discoordinate fashion and regulated by different factors.
Brody
J S
JS
Pulmonary Center, Boston University School of Medicine, MA 02118.
Joyce-Brady
M
M
D000328:Adult; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000302:isolation & purification; D015415:Biomarkers; D002454:Cell Differentiation; D006801:Humans; D037102:Lectins; D008562:Membrane Glycoproteins / Q000378:metabolism; D008970:Molecular Weight; D037121:Plant Lectins; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000276:immunology / Q000378:metabolism
D015295:Antigens, Tumor-Associated, Carbohydrate; D015415:Biomarkers; D037102:Lectins; D008562:Membrane Glycoproteins; D037121:Plant Lectins; C034551:maclurin