scholarly journals Lectin activity of the major surfactant protein (SP-A) may participate in, but is not required for, binding to rat type II cells.

1992 ◽  
Vol 40 (5) ◽  
pp. 643-649 ◽  
Author(s):  
T Thorkelsson ◽  
G M Ciraolo ◽  
G F Ross ◽  
J A Whitsett ◽  
R E Morris
Keyword(s):  
Protein A ◽  
Complex Mixture ◽  
Surfactant Protein ◽  
Structural Features ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lectin Activity ◽  
Type Ii Cell

Pulmonary surfactant is a complex mixture of lipids and proteins, of which surfactant protein A (SP-A) is the most abundant glycoprotein. The SP-A molecule has several distinct structural features that include a lectin-like domain, sharing structural features with other mammalian lectins. We have tested the hypothesis that lectin activity of the SP-A molecule is required for the binding to its receptor on the surface of alveolar Type II cells. By using colloidal gold immunocytochemistry in conjunction with electron microscopy, we evaluated the ability of mannosylated proteins to inhibit canine SP-A binding to rat Type II cells in vitro. After preincubation of SP-A with the mannosylated protein horse-radish peroxidase (HRP), SP-A was incubated with isolated filter-grown Type II cells. HRP did not alter the binding of SP-A to the Type II cell surface. Evidence that SP-A did bind to HRP was shown by coincident observation of gold-labeled SP-A and HRP precipitates. These results provide visual evidence that the lectin activity associated with SP-A is not required for its binding to receptor on rat alveolar Type II epithelial cells.

Degradation of surfactant lipids and surfactant protein A by alveolar macrophages in vitro

1995 ◽  
Vol 268 (5) ◽  
pp. L772-L780 ◽  
Author(s):  
J. R. Wright ◽  
D. C. Youmans
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Dependent Manner ◽  
Type Ii ◽  
Alveolar Type Ii Cell ◽  
Degradation Rates ◽  
Type Ii Cell

Pulmonary surfactant is synthesized and secreted into the airspaces by the alveolar type II cell. After it is secreted, surfactant undergoes a series of poorly understood transformations resulting in formation of a surface tension-reducing surface at the air-liquid interface. The by-products of the surface film and/or other products of surfactant metabolism are eventually cleared from the alveolar space. Both the alveolar type II cell and the macrophage are thought to be involved in surfactant clearance and have been shown to internalize surfactant lipid in vitro. The goal of the current investigation was to characterize further and to quantitate the role of the macrophage in surfactant clearance by investigating the uptake and metabolism of surfactant lipids and surfactant protein A (SP-A) by macrophages in vitro. SP-A enhanced the uptake of lipids by macrophages in a time-, temperature-, and concentration-dependent manner. In contrast, neither of the collagen-like proteins SP-D or C1q enhanced the uptake. Phosphatidylcholine was rapidly degraded by macrophages and the degradation occurred both in the presence and absence of SP-A. In addition, macrophages degrade SP-A by a process that is time- and temperature-dependent. These results and calculations of uptake and degradation rates suggest that macrophages may contribute significantly to the process of surfactant clearance.

Exposure of surfactant protein A to ozone in vitro and in vivo impairs its interactions with alveolar cells

1992 ◽  
Vol 262 (1) ◽  
pp. L63-L68 ◽  
Author(s):  
R. S. Oosting ◽  
J. F. Van Iwaarden ◽  
L. Van Bree ◽  
J. Verhoef ◽  
L. M. Van Golde ◽  
...  
Keyword(s):  
Superoxide Anion ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Type Ii ◽  
Superoxide Anion Production ◽  
Anion Production

This study focused on the question of whether exposure of surfactant protein A (SP-A) to ozone affected properties of this protein that may be involved in regulating alveolar type II cell and alveolar macrophage functions. In vitro exposure of human or canine SP-A to ozone reduced the ability of this protein to inhibit phorbol-ester induced secretion of [3H]phosphatidylcholine by alveolar type II cells in culture. Ozone-exposed human SP-A showed a decreased ability to enhance phagocytosis of herpes simplex virus and to stimulate superoxide anion production by alveolar macrophages. Experiments with elastase showed that ozone-exposed canine SP-A was more susceptible to proteolysis. A conformational change of the protein could underlie this phenomenon. Surfactant isolated from ozone-exposed rats (0.4 ppm ozone for 12 h) was also less able to stimulate superoxide anion production by alveolar macrophages than surfactant from control rats, which suggested that SP-A in vivo was also susceptible to ozone. The results of this study suggest that SP-A-alveolar cell interactions can be inhibited by ozone exposure, which may contribute to the toxicity of ozone in the lungs.

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)

Derivation of tumorigenic and non-tumorigenic mouse alveolar type-II cell lines from fetal type-II cells after a combinedin vivo/in vitro carcinogen treatment

1992 ◽  
Vol 52 (2) ◽  
pp. 290-297 ◽  
Author(s):  
L. C. J. M. Oomen ◽  
J. Calafat ◽  
A. A. W. Ten Have-Opbroek ◽  
J. Egberts ◽  
P. Demant
Keyword(s):  
Cell Lines ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cell ◽  
Type Ii Cell

Binding and uptake of surfactant protein D by freshly isolated rat alveolar type II cells

2000 ◽  
Vol 278 (4) ◽  
pp. L830-L839 ◽  
Author(s):  
Joel F. Herbein ◽  
Jordan Savov ◽  
Jo Rae Wright
Keyword(s):  
Surfactant Protein ◽  
Surfactant Protein D ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Dependent Manner ◽  
Type Ii ◽  
Lipid Uptake ◽  
Lamellar Bodies ◽  
Alveolar Type Ii Cells ◽  
Type Ii Cell

Alveolar type II cells secrete, internalize, and recycle pulmonary surfactant, a lipid and protein complex that increases alveolar compliance and participates in pulmonary host defense. Surfactant protein (SP) D, a collagenous C-type lectin, has recently been described as a modulator of surfactant homeostasis. Mice lacking SP-D accumulate surfactant in their alveoli and type II cell lamellar bodies, organelles adapted for recycling and secretion of surfactant. The goal of current study was to characterize the interaction of SP-D with rat type II cells. Type II cells bound SP-D in a concentration-, time-, temperature-, and calcium-dependent manner. However, SP-D binding did not alter type II cell surfactant lipid uptake. Type II cells internalized SP-D into lamellar bodies and degraded a fraction of the SP-D pool. Our results also indicated that SP-D binding sites on type II cells may differ from those on alveolar macrophages. We conclude that, in vitro, type II cells bind and recycle SP-D to lamellar bodies, but SP-D may not directly modulate surfactant uptake by type II cells.

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 Ca2+-dependent binding of annexin IV to surfactant protein A and lamellar bodies in alveolar type II cells

1995 ◽  
Vol 312 (1) ◽  
pp. 175-181 ◽  
Author(s):  
H Sohma ◽  
N Matsushima ◽  
T Watanabe ◽  
A Hattori ◽  
Y Kuroki ◽  
...  
Keyword(s):  
Protein A ◽  
Immunoblot Analysis ◽  
Surfactant Protein ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lamellar Bodies ◽  
Alveolar Type Ii Cells ◽  
Sepharose 4B ◽  
Annexin Iv

Surfactant protein A (SP-A), a lung-specific glycoprotein in pulmonary surfactant, is synthesized and secreted from the alveolar type II cells. It has been shown that SP-A is a Ca(2+)-binding protein with several binding sites and that the high-affinity site(s) is located in the C-terminal region of SP-A. In the present study we isolated the proteins from bovine lung soluble fraction that bind to SP-A in a Ca(2+)-dependent manner using DEAE-Sephacel and SP-A-conjugated Sepharose 4B. At least three different protein bands with molecular masses of 24.5, 32, and 33 kDa were observed on SDS/PAGE. The main protein, with molecular mass of 32 kDa, was identified as annexin IV by the partial-amino-acid-sequence analyses and an immunoblot analysis with anti-(annexin IV) antiserum. We also found from the immunoblot analysis that the cytosolic fraction of isolated rat alveolar type II cells contains annexin IV. In addition, when rat lung cytosol was loaded on to the lung lamellar body-conjugated Sepharose 4B in the presence of Ca2+, two proteins, with molecular masses of 32 and 60 kDa on SDS/PAGE respectively, were eluted with EGTA. The 32 kDa protein was shown to be annexin IV by an immunoblot analysis with the antiserum against annexin IV. The lung annexin IV augmented the Ca(2+)-induced aggregation of the lung lamellar bodies from rats. However, the augmentation of aggregation of the lung lamellar bodies by annexin IV was attenuated when the lamellar bodies were preincubated with polyclonal anti-SP-A antibodies. SP-A bound to annexin IV under conditions where contaminated lipid was removed. These results suggest that SP-A bound to annexin IV based on protein-protein interaction, though both proteins are phospholipid-binding proteins. All these findings suggest that the interaction between SP-A and annexin IV may have some role in 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.

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