scholarly journals Alveolar type II cells express a high-affinity receptor for pulmonary surfactant protein A.

1988 ◽  
Vol 85 (15) ◽  
pp. 5566-5570 ◽  
Author(s):  
Y. Kuroki ◽  
R. J. Mason ◽  
D. R. Voelker
Keyword(s):  
Pulmonary Surfactant ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
High Affinity ◽  
High Affinity Receptor ◽  
Affinity Receptor

Pulmonary surfactant protein A-mediated uptake of phosphatidylcholine by alveolar type II cells

1993 ◽  
Vol 265 (2) ◽  
pp. L193-L199 ◽  
Author(s):  
A. Tsuzuki ◽  
Y. Kuroki ◽  
T. Akino
Keyword(s):  
Pulmonary Surfactant ◽  
Protein A ◽  
Lamellar Body ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lamellar Bodies ◽  
Pulmonary Surfactant Protein

Pulmonary surfactant protein A (SP-A)-mediated uptake of phosphatidylcholine (PC) by alveolar type II cells was investigated. SP-A enhanced the uptake of liposomes containing dipalmitoylphosphatidylcholine (DPPC), 1-palmitoyl-2-linoleoyl phosphatidylcholine (PLPC), or 1,2-dihexadecyl-sn-glycero-3-phosphocholine (DPPC-ether), a diether analogue of DPPC, but about twice as much DPPC was taken up by type II cells as PLPC or DPPC-ether. When subcellular distribution was analyzed, 51.3 +/- 2.9% (mean +/- SD, n = 3) of cell-associated radiolabeled DPPC was recovered in the lamellar body-rich fraction in the presence of SP-A, whereas only 19.3 +/- 1.9% (mean +/- SD, n = 3) was found to this fraction in the absence of SP-A. When type II cells were incubated either with DPPC at 0 degree C or with DPPC-ether at 37 degrees C, or no cells were included, low proportions of the cell-associated lipids were present in the fractions corresponding to lamellar bodies even in the presence of SP-A. Anti-SP-A antibody significantly reduced the radioactivity incorporated into the lamellar body fraction. Phosphatidylcholine that had been incorporated into lamellar bodies remained largely intact when SP-A was present. Subcellular fractionations of type II cells with radiolabeled SP-A and DPPC revealed that the sedimentation characteristics of cell-associated SP-A are different from those of DPPC, although a small broad peak of radiolabeled SP-A was found in the lamellar body fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Type II Cells, Surfactant Protein A (SP-A), and the Phospholipid Components of Surfactant in Acute Silicosis in the Rat

1989 ◽  
Vol 140 (2) ◽  
pp. 460-470 ◽  
Author(s):  
Hiroshi Kawada ◽  
Tadashi Horiuchi ◽  
John M. Shannon ◽  
Yoshio Kuroki ◽  
Dennis R. Voelker ◽  
...  
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells

scholarly journals Internalization of surfactant protein A (SP-A) into lamellar bodies of rat alveolar type II cells in vitro.

1993 ◽  
Vol 41 (1) ◽  
pp. 57-70 ◽  
Author(s):  
M Kalina ◽  
F X McCormack ◽  
H Crowley ◽  
D R Voelker ◽  
R J Mason
Keyword(s):  
Protein A ◽  
Fluid Phase ◽  
Surfactant Protein ◽  
Biologically Active ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lamellar Bodies ◽  
Alveolar Type Ii Cells

Pulmonary surfactant is thought to be internalized and processed for reuse by alveolar Type II cells. In the present study we followed the internalization and intracellular trafficking of purified surfactant protein A (SP-A) by primary cultures of alveolar Type II cells. Internalization of native rat SP-A was compared with that of recombinant rat and human SP-A isolated from a patient with alveolar proteinosis. All SP-A species were conjugated with colloidal gold for visualization by electron microscopy. The gold conjugates were biologically active, as demonstrated by inhibition of phospholipid secretion from alveolar Type II cells. The SP-A-gold conjugates were internalized to lamellar bodies (LB) via the endosomal system, which included both electron-lucent and -dense multivesicular bodies. Labeling of LB was time dependent, and after 7 hr 30-40% of these organelles were labeled. Alkylation of SP-A greatly reduced internalization, as did an excess of non-conjugated SP-A. No qualitative differences in uptake were observed with the three forms of SP-A. The percent of labeled LB was similar (30-40%) after 7 hr of internalization with the three species of SP-A. The recombinant SP-A produced using a baculovirus vector lacked hydroxyproline and had an altered oligosaccharide, but these features did not affect its internalization or the rate of LB labeling. Internalization of the gold-conjugated SP-A and endocytosis of the fluid-phase marker Lucifer Yellow were related to the shape of Type II cells. Both uptake of SP-A, which is receptor mediated, and fluid-phase endocytosis were found to be less active in the flattened than in the rounded cells. Therefore, cell shape and hence cytoskeletal organization may play an important role in SP-A recycling. However, it is possible that both morphology and decreased endocytosis are independent manifestations related to the loss of differentiated function of cultured Type II cells.

scholarly journals Human surfactant protein A with two distinct oligomeric structures which exhibit different capacities to interact with alveolar type II cells

1996 ◽  
Vol 317 (3) ◽  
pp. 939-944 ◽  
Author(s):  
Akiko HATTORI ◽  
Yoshio KUROKI ◽  
Hitoshi SOHMA ◽  
Yoshinori OGASAWARA ◽  
Toyoaki AKINO
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Dependent Manner ◽  
Type Ii ◽  
Concentration Dependent Manner ◽  
Lower Affinity ◽  
Alveolar Proteinosis

The lung lavage fluids from patients with pulmonary alveolar proteinosis have been generally used as a source for human surfactant protein A (SP-A). We have recently found that a multimerized form of SP-A oligomer (alveolar proteinosis protein-I, APP-I) exists besides the normal-sized octadecamer (APP-II) in SP-As isolated from the patients. When analysed by Bio-Gel A15m column chromatography in 5 mM Tris buffer (pH 7.4), the apparent molecular masses of APP-I and APP-II were 1.65 MDa and 0.93 MDa, respectively. Gel-filtration analysis also revealed that APP-II is clearly separated from APP-I in the presence of 2 mM Ca2+ and 150 mM NaCl. We investigated the abilities of both SP-A oligomers to regulate phospholipid secretion and to bind to alveolar type II cells. Although APP-I inhibited lipid secretion, it was clearly a less effective inhibitor than APP-II. IC50 for inhibition of lipid secretion was apparently 0.23±0.08 µg/ml (0.14±0.05 nM) and 0.055±0.019 µg/ml (0.059±0.020 nM) for APP-I and APP-II, respectively. Both proteins bound to monolayers of type II cells in a concentration-dependent manner; however, APP-I clearly had a lower affinity to bind to type II cells. The apparent dissociation contants were, Kd = 2.31±0.70 µg/ml (1.40±0.43 nM) and 0.89±0.22 µg/ml (0.95±0.24 nM) for APP-I and APP-II, respectively. Excess unlabelled rat SP-A replaced 45% of 125I-APP-I and 77% of 125I-APP-II for type II cell binding. Although 125I-APP-II competed with excess unlabelled APP-I or APP-II, 125I-APP-I failed to compete and instead its binding rather increased in the presence of unlabelled APPs. The biotinylated APP-I bound to APP-I and APP-II coated on to microtitre wells in a concentration-dependent manner, indicating that APP-I interacts with APPs. This study demonstrates that the multimerized form of human SP-A oligomer exhibits the following attributes: (1) the reduced capacity to regulate phospholipid secretion from type II cells, and (2) lower affinity to bind to type II cells, and that the integrity of a flower-bouquet-like octadecameric structure of SP-A oligomer is important for the expression of full activity of this protein, indicating the importance of the oligomeric structure of mammalian lectins with collagenous domains.

scholarly journals Role of the C-terminal domain of pulmonary surfactant protein A in binding to alveolar type II cells and regulation of phospholipid secretion

1993 ◽  
Vol 291 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Y Murata ◽  
Y Kuroki ◽  
T Akino
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
Lipid Secretion ◽  
Terminal Domain

Surfactant protein A (SP-A), with a reduced denatured molecular mass of 26-38 kDa, is characterized by a collagen-like sequence in the N-terminal half of the protein. This protein forms an oligomeric structure which is dependent upon this collagenous domain. SP-A has been demonstrated to function as an inhibitor of phospholipid secretion by primary cultures of alveolar type II cells via a cell surface receptor for the protein. However, the receptor-binding domain of SP-A has not been identified. The purpose of the present study was to investigate the role of the C-terminal domain of SP-A in binding to type II cells and regulation of phospholipid secretion. A monoclonal antibody to human SP-A, whose epitope was localized at the C-terminal domain of the protein, abolished the inhibitory activity of human SP-A on lipid secretion by type II cells, and attenuated the ability of human SP-A to compete with 125I-(rat SP-A) for receptor binding. SP-A was then digested with collagenase and the collagenase-resistant fragment (CRF), which is the C-terminal domain of SP-A (thus lacking the N-terminal domain), was isolated. Gel filtration chromatography revealed that CRF exists as a monomer in solution containing Ca2+. CRF had the ability to inhibit phospholipid secretion, although at a higher concentration than for SP-A, and was also able to compete with 125I-(rat SP-A) for binding to type II cells. A direct binding study showed that CRF bound to type II cells in a concentration-dependent manner. The present study demonstrates that the non-collagenous, C-terminal, domain of SP-A is responsible for the protein's inhibitory effect on lipid secretion and its binding to type II cells.

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