Distribution of surfactant protein A in rat lung.

1994 ◽  
Vol 11 (4) ◽  
pp. 405-415 ◽  
Author(s):  
I R Doyle ◽  
H A Barr ◽  
T E Nicholas
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Rat Lung

Localization of surfactant protein A (SP-A) in alveolar macrophage subpopulations of normal and fibrotic rat lung

1994 ◽  
Vol 102 (5) ◽  
pp. 345-352 ◽  
Author(s):  
M. Kasper ◽  
G. Haroske ◽  
D. Schuh ◽  
M. M�ller ◽  
R. Koslowski ◽  
...  
Keyword(s):  
Alveolar Macrophage ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Rat Lung ◽  
Macrophage Subpopulations

ATP and adenosine 3',5'-cyclic monophosphate stimulate the synthesis of surfactant protein A in rat lung

1993 ◽  
Vol 264 (5) ◽  
pp. L431-L437 ◽  
Author(s):  
A. Wali ◽  
M. F. Beers ◽  
C. Dodia ◽  
S. I. Feinstein ◽  
A. B. Fisher
Keyword(s):  
Total Protein ◽  
Protein A ◽  
Lamellar Body ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Enzyme Linked Immunosorbent Assay ◽  
Translational Efficiency ◽  
Rat Lung ◽  
Body Protein ◽  
Cyclic Monophosphate

Synthesis and secretion of surfactant protein A (SP-A) were studied in the isolated perfused rat lung using Trans35S-label (approximately 85% methionine, 15% cysteine) in the perfusate with or without 1 mM ATP or 0.1 mM 8-bromoadenosine 3',5',-cyclic monophosphate (8-BrcAMP) for up to 6 h of perfusion. By enzyme-linked immunosorbent assay, the SP-A content was 36 +/- 0.3% of total protein in extracellular surfactant and 10.8 +/- 1.9% of total protein in lamellar bodies of control lungs; these relativr proportions were maintained in the presence of ATP or 8-BrcAMP. Incorporation of [35S]methionine (cysteine) into the surfactant and lamellar body protein fraction could be detected at 4 h of perfusion. At 6 h, specific activity of total protein [disintegrations per minute (dpm)/micrograms)] was significantly increased in both the surfactant (54%) and lamellar body fractions (30%) under the influence of either secretagogue compared with control conditions. In the presence of ATP, there was a significant increase in the SP-A immunoprecipitable counts of 61 and 72% in extra- and intracellular compartments, respectively. However, no significant change was observed in the relative abundance of SP-A mRNA between control and secretagogue-treated lungs. This dissociation of SP-A mRNA abundance and label incorporation into protein indicates that alteration in translational efficiency or posttranslational factors may be involved in the secretagogue-induced stimulation of SP-A synthesis.

Alveolar uptake of lipid and protein components of surfactant

1991 ◽  
Vol 261 (4) ◽  
pp. L334-L340 ◽  
Author(s):  
A. B. Fisher ◽  
C. Dodia ◽  
A. Chander
Keyword(s):  
Plasma Membranes ◽  
Protein A ◽  
Surfactant Protein ◽  
Lung Lavage ◽  
Surfactant Protein A ◽  
Rat Lung ◽  
Protein Breakdown ◽  
Aqueous Fraction ◽  
Natural Surfactant ◽  
Protein Components

We investigated the clearance of radiolabeled natural surfactant from the alveolar space of the isolated perfused rat lung. 3H, 35S-natural surfactant was prepared from rat lungs that had been perfused with [methyl-3H]choline and [35S]methionine. The biosynthesized material contained greater than 95% of 3H in phosphatidylcholine (PC) and approximately 80% of 35S in surfactant protein A. Natural surfactant (1 mumol PC) was instilled into the trachea; lungs were analyzed 5 min later or after 2 h perfusion to determine surfactant uptake, defined as lung lavage-resistant 3H or 35S [% of instilled disintegrations per minute(dpm)]. Uptake at 5 min was 31.4 +/- 0.37% for 3H and 31.9 +/- 0.85% for 35S (mean +/- SE, n = 4). At 2 h, uptake was 46.6 +/- 0.96% for 3H and 45.8 +/- 1.1% for 35S (n = 7). In the presence of 0.1 mM 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP), uptake at 2 h for both 3H and 35S was stimulated to approximately 57% of instilled dpm (n = 4). Microsomes and plasma membranes isolated from lung homogenates had a ratio of 3H to 35S that was similar to the original surfactant, whereas 3H/35S in isolated lamellar bodies was increased 2.1-fold. Degradation of lipid was indicated by finding 13.4 +/- 0.65% of homogenate 3H in the aqueous fraction of lung extract after 2 h perfusion; only 2.3 +/- 0.47% of 35S dpm were soluble in trichloroacetic acid, suggesting significantly less protein breakdown. Lipid degradation was increased more than twofold by 8-BrcAMP, whereas protein degradation was not changed significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Surfactant protein A is localized at the corners of the pulmonary tubular myelin lattice.

1991 ◽  
Vol 39 (10) ◽  
pp. 1331-1336 ◽  
Author(s):  
W F Voorhout ◽  
T Veenendaal ◽  
H P Haagsman ◽  
A J Verkleij ◽  
L M van Golde ◽  
...  
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Alveolar Type ◽  
Type Ii ◽  
Rat Lung ◽  
Lamellar Bodies ◽  
20 Nm

Immunogold labeling on sections of a freeze-substituted tubular myelin-enriched fraction isolated from a bronchoalveolar lavage of rat lung showed that surfactant protein A (SP-A) occurs predominantly at the corners of the tubular myelin lattice. Seventy-nine percent of the gold particles were located within 20 nm from a corner. Extracellular SP-A was detected only in the tubular myelin lattice and not in vesicles or secreted lamellar bodies. Ultra-thin cryosections of rat lung fixed in vivo showed that intracellular SP-A was distributed homogeneously over the stacked membranes of lamellar bodies in alveolar Type II cells. The presence of SP-A at the corners of the tubular myelin lattice suggests an important role of this protein in the formation and/or maintenance of this highly ordered lattice.

Surfactant Protein A Binding to Cytomegalovirus Proteins Enhances Virus Entry into Rat Lung Cells

2000 ◽  
Vol 23 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Christiane Weyer ◽  
Robert Sabat ◽  
Heide Wissel ◽  
Detlev H. Krüger ◽  
Paul A. Stevens ◽  
...  
Keyword(s):  
Virus Entry ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Lung Cells ◽  
Rat Lung

Regulation of surfactant protein A mRNA by hormones and butyrate in cultured fetal rat lung

1990 ◽  
Vol 259 (6) ◽  
pp. L488-L495 ◽  
Author(s):  
K. V. Nichols ◽  
J. Floros ◽  
D. W. Dynia ◽  
S. V. Veletza ◽  
C. M. Wilson ◽  
...  
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Rat Lung ◽  
Acid Analogue ◽  
Camp Analogue ◽  
Fetal Rat ◽  
Fetal Rat Lung ◽  
Dose Dependent Fashion ◽  
Diabetic Mothers

We have previously shown that dexamethasone, triiodothyronine (T3) and dibutyryl adenosine 3',5'-cyclic monophosphate (cAMP) stimulate phosphatidylcholine (PC) synthesis in fetal rat lung explants in culture. There are also additive interactions between these agents with regard to PC synthesis. In this study we examined the regulation of surfactant protein A (SP-A) mRNA in fetal rat lung in culture. Dexamethasone increased SP-A mRNA in the explants in a dose-dependent fashion (1–200 nM), but T3 did not. Whereas 8-bromo-cAMP increased SP-A mRNA, a decrease was observed with dibutyryl cAMP. These findings support the view that at least some of the genes involved in the synthesis of the various components of surfactant are independently regulated. Since we observed differences in the effects of a cAMP analogue which contained butyrate and one that did not, explants were then cultured with Na butyrate, a known regulator of gene expression. A significant decrease in SP-A mRNA was observed at mM concentrations. Exposure of the explants to alpha-aminobutyric acid, a butyric acid analogue which is elevated in the blood of infants of diabetic mothers, resulted in a significant decrease in SP-A mRNA at a concentration 1/25 of that required for Na butyrate. This observation raises the question of whether the decreased SP-A levels reported in fetuses of diabetic mothers may, at least in part, be related to this metabolite.

Surfactant protein-A plays an important role in lung surfactant clearance: evidence using the surfactant protein-A gene-targeted mouse

2008 ◽  
Vol 294 (2) ◽  
pp. L325-L333 ◽  
Author(s):  
Sandra R. Bates ◽  
Chandra Dodia ◽  
Jian-Qin Tao ◽  
Aron B. Fisher
Keyword(s):  
Lung Surfactant ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Type Ii Cells ◽  
Type Ii ◽  
Rat Lung ◽  
Coated Pits ◽  
Receptor Mediated Endocytosis ◽  
Mouse Lungs

Previous studies with the isolated perfused rat lung showed that both clathrin- and actin-mediated pathways are responsible for endocytosis of dipalmitoylphosphatidylcholine (DPPC)-labeled liposomes by granular pneumocytes in the intact lung. Using surfactant protein-A (SP-A) gene-targeted mice, we examined the uptake of [3H]DPPC liposomes by isolated mouse lungs under basal and secretagogue-stimulated conditions. Unilamellar liposomes composed of [3H]DPPC: phosphatidylcholine:cholesterol:egg phosphatidylglycerol (10:5:3:2 mol fraction) were instilled into the trachea of anesthetized mice, and the lungs were perfused (2 h). Uptake was calculated as percentage of instilled disintegrations per minute in the postlavaged lung. Amantadine, an inhibitor of clathrin and, thus, receptor-mediated endocytosis via clathrin-coated pits, decreased basal [3H]DPPC uptake by 70% in SP-A +/+ but only by 20% in SP-A −/− lung, data compatible with an SP-A/receptor-regulated lipid clearance pathway in the SP-A +/+ mice. The nonclathrin, actin-dependent process was low in the SP-A +/+ lung but accounted for 55% of liposome endocytosis in the SP-A −/− mouse. With secretagogue (8-bromoadenosine 3′,5′-cyclic monophosphate) treatment, both clathrin- and actin-dependent lipid clearance were elevated in the SP-A +/+ lungs while neither pathway responded in the SP-A −/− lungs. Binding of iodinated SP-A to type II cells isolated from both genotypes of mice was similar indicating a normal SP-A receptor status in the SP-A −/− lung. Inclusion of SP-A with instilled liposomes served to “rescue” the SP-A −/− lungs by reestablishing secretagogue-dependent enhancement of liposome uptake. These data are compatible with a major role for receptor-mediated endocytosis of DPPC by granular pneumocytes, a process critically dependent on SP-A.

Differential changes in SP-A and disaturated phospholipids in the isolated perfused rat lung and in vivo

1996 ◽  
Vol 271 (3) ◽  
pp. L374-L382 ◽  
Author(s):  
I. R. Doyle ◽  
H. A. Barr ◽  
K. G. Davidson ◽  
T. E. Nicholas
Keyword(s):  
Tidal Volume ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Rat Lung ◽  
Lamellar Bodies ◽  
The Relationship

Alveolar disaturated phospholipids (DSPA) increase in vivo in rats with hyperpnea and in isolated perfused lungs (IPL) in response to either salbutamol or increasing tidal volume (VT). Because surfactant protein-A (SP-A) may play a role in surfactant homeostasis, we have examined the relationship between SP-A and DSP in the alveolus lamellar bodies (LB-A), and in a vesicular (LB-B) lung subfraction. Whereas 2 h swimming increased total DSPA (approximately 48%), it had no effect on alveolar SP-A (SP-AA). In the IPL, salbutamol increased total DSPA (approximately 30%) and SP-AA (approximately 41%); increasing VT (2.5-fold) only increased DSPA (approximately 22%). SP-A and DSP also varied differentially in the tubular myelin-rich and -poor subfractions. In both the IPL and in vivo, we found inverse relationships between DSPA and SP-AA/DSPA, indicating that although SP-AA and DSPA are related, they vary independently. Whereas total SP-AA/DSPA varied between 0.046 and 0.074, it remained constant in LB-A (approximately 0.015) and LB-B (approximately 0.010), suggesting that DSP and SP-A are secreted differentially and that only a small portion of SP-AA is derived from lamellar bodies.

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