Ultrastructure of phospholipid mixtures reconstituted with surfactant proteins B and D.
Surfactant protein (SP)-D is secreted from pulmonary alveolar type II cells into the alveolar lumen where potential interactions with surfactant lipids might occur. SP-D binds phosphatidylinositol (PI), a component of mammalian surfactants that is increased in a variety of injury states. We investigated the ultrastructure and properties of lipid protein recombinants that included SP-D, PI, and SP-B and compared these with recombinants based on SP-A. SP-D had a profound effect on the organization of phospholipid vesicles containing PI and SP-B, promoting the formation of atypical but highly ordered and surface-active tubular aggregates distinct in their dimensions and shape from the classical tubular myelin formed by SP-A. We also found both types of tubules in the secretions of type II cells maintained in long-term culture. These results suggest that surface atypical tubules can be formed with SP-D in vitro and in vivo.
Poulain
F R
FR
Cardiovascular Research Institute and Departments of Pediatrics, Medicine, and Physiology, University of California San Francisco, San Francisco, California, USA. poulain@itsa.ucsf.edu
Akiyama
J
J
Allen
L
L
Brown
C
C
Chang
R
R
Goerke
J
J
Dobbs
L
L
Hawgood
S
S
D000818:Animals; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D018076:DNA, Complementary; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008854:Microscopy, Electron; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011510:Proteolipids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013499:Surface Properties
D018076:DNA, Complementary; D006023:Glycoproteins; D010743:Phospholipids; D011510:Proteolipids; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants; D011994:Recombinant Proteins