Pulmonary surfactant protein SP‐B promotes exocytosis of lamellar bodies in alveolar type II cells

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)

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Interaction of phospholipid liposomes with plasma membrane isolated from alveolar type II cells: effect of pulmonary surfactant protein A

Biochimica et Biophysica Acta (BBA) - Biomembranes ◽

10.1016/0005-2736(96)00011-9 ◽

1996 ◽

Vol 1281 (1) ◽

pp. 53-59 ◽

Cited By ~ 4

Author(s):

Yoshio Kuroki ◽

Masanori Shiratori ◽

Yoshinori Ogasawara ◽

Akiko Hattori ◽

Wataru Tsunezawa ◽

...

Keyword(s):

Pulmonary Surfactant ◽

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Alveolar Type ◽

Type Ii Cells ◽

Type Ii ◽

Alveolar Type Ii Cells ◽

Phospholipid Liposomes ◽

Pulmonary Surfactant Protein

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GM130 regulates pulmonary surfactant protein secretion in alveolar type II cells

Science China Life Sciences ◽

10.1007/s11427-020-1875-x ◽

2021 ◽

Author(s):

Qianqian Pang ◽

Chunyi Liu ◽

Yulong Qiao ◽

Jian Zhao ◽

Sin Man Lam ◽

...

Keyword(s):

Protein Secretion ◽

Pulmonary Surfactant ◽

Surfactant Protein ◽

Alveolar Type ◽

Type Ii Cells ◽

Type Ii ◽

Alveolar Type Ii Cells ◽

Pulmonary Surfactant Protein

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An En Bloc Staining Protocol Improves The Preservation of Lamellar Bodies in Alveolar Type II Epithelial Cells for Transgenic Mice Expressing Modified Pulmonary Surfactant Protein B

Microscopy and Microanalysis ◽

10.1017/s1431927600024387 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 852-853

Author(s):

C.-L. Na ◽

D. C. Beck ◽

J. S. Breslin ◽

S. E. Wert ◽

T. E. Weaver

Keyword(s):

Pulmonary Surfactant ◽

Surfactant Protein ◽

Alveolar Type ◽

Type Ii ◽

Lamellar Bodies ◽

En Bloc ◽

Surfactant Protein B ◽

Staining Protocol ◽

Pulmonary Surfactant Protein B ◽

Pulmonary Surfactant Protein

The extraction of lipids and phospholipids during dehydration and plastic embedding steps results in poor preservation of the phospholipid rich lamellar bodies (LB) in alveolar type II epithelial cells. To achieve better retention of phospholipids, we combined inflation fixation and an en bloc staining protocol using 4% aqueous uranyl acetate (UA), thereby improving the preservation of the LBs for both the wild type and transgenic mice expressing modified pulmonary surfactant protein B (SP-B; Akinbi et al., 1997).Lungs of 6-8 week-old mice were inflation fixed (Bunkingham and Weyder, 1981) with ice cold 2% paraformaldehye and 2% glutaraldehyde in 0.1 M sodium cacodylate buffer (SCB), pH 7.3, postfixed in fresh fixative at 4 °C overnight, incubated with 1% osmium tetroxide in 0.1 M SCB at room temperature for 2 hours, and stained en bloc with 4% aqueous UA overnight.

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

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.2000.278.4.l830 ◽

2000 ◽

Vol 278 (4) ◽

pp. L830-L839 ◽

Cited By ~ 15

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.

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

Biochemical Journal ◽

10.1042/bj3120175 ◽

1995 ◽

Vol 312 (1) ◽

pp. 175-181 ◽

Cited By ~ 14

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.

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

Journal of Histochemistry & Cytochemistry ◽

10.1177/41.1.8417113 ◽

1993 ◽

Vol 41 (1) ◽

pp. 57-70 ◽

Cited By ~ 18

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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Binding, uptake, and localization of surfactant protein B in isolated rat alveolar type II cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1992.262.6.l699 ◽

1992 ◽

Vol 262 (6) ◽

pp. L699-L707 ◽

Cited By ~ 8

Author(s):

J. S. Breslin ◽

T. E. Weaver

Keyword(s):

Surfactant Protein ◽

Endocytic Pathway ◽

Alveolar Type ◽

Type Ii Cells ◽

Type Ii ◽

Lamellar Bodies ◽

Coated Pits ◽

Alveolar Type Ii Cells ◽

Surfactant Protein B ◽

Protein B

This study reports the ability of rat alveolar type II cells to internalize mature bovine surfactant protein B (SP-B) in vitro. Isolated type II cells were incubated with labeled SP-B, and binding and internalization were studied biochemically and morphologically. Biochemical analyses demonstrated a time-dependent association of 125I-labeled SP-B with type II cells; binding steadily increased through 4 h and then remained constant through 20 h of incubation. The association of [3H]SP-B with type II cells was characterized via light and electron microscopic autoradiography. Significant quantities of [3H]SP-B were found at the plasma membrane, in the endocytic pathway, and in lamellar bodies. The pathway of SP-B internalization was not altered by the presence of whole rat surfactant; however, the quantity of SP-B internalized into lamellar bodies was increased. 3[H]SP-B was not associated with coated pits and colocalized with horseradish peroxidase (HRP), consistent with receptor-independent internalization. Cell-associated SP-B was not degraded and was detected in lamellar bodies undergoing exocytosis. These results suggest that SP-B may follow a recycling pathway similar to that previously reported for surfactant phospholipids.

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