Composition of extracellular matrix of type II pulmonary epithelial cells in primary culture

1995 ◽  
Vol 269 (6) ◽  
pp. L754-L765 ◽  
Author(s):  
S. E. Dunsmore ◽  
C. Martinez-Williams ◽  
R. A. Goodman ◽  
D. E. Rannels
Keyword(s):  
Extracellular Matrix ◽  
Epithelial Cells ◽  
Primary Culture ◽  
Biological Effects ◽  
Primary Cultures ◽  
Matrix Composition ◽  
Type Ii Cells ◽  
Type Ii ◽  
Pulmonary Epithelial Cells ◽  
Culture Surface

Type II pulmonary epithelial cells in primary culture synthesize and deposit an extracellular matrix which has reciprocal biological effects on cellular differentiation. The present work establishes conditions for metabolic labeling of matrix constituents and for separation of cells from the associated matrix; it also defines matrix composition, which does not appear to change qualitatively between days 2 and 6 of primary culture. Type II cells synthesize and deposit a spectrum of radiolabeled components on the culture surface. These include fibronectin, laminin, type IV collagen, and plasminogen activator inhibitor-1, along with additional unidentified proteins. Few radiolabeled proteins in medium conditioned by type II cells bind nonspecifically to the culture surface in the absence of cells. Fibroblasts and macrophages, which may contaminate the primary cultures, do not appear to contribute substantially to the type II cell matrix. These results demonstrate that type II cells synthesize and deposit a complex multicomponent extracellular matrix. The work provides a basis for further investigations of bidirectional interactions between type II cells and the extracellular matrix.

Extracellular matrix synthesis and turnover by type II pulmonary epithelial cells

1992 ◽  
Vol 262 (5) ◽  
pp. L582-L589 ◽  
Author(s):  
D. E. Rannels ◽  
S. E. Dunsmore ◽  
R. N. Grove
Keyword(s):  
Extracellular Matrix ◽  
Steady State ◽  
Epithelial Cells ◽  
Primary Cultures ◽  
Calf Serum ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Pulmonary Epithelial Cells ◽  
Type Ii Cell

Both type I and type II pulmonary epithelial cells contact the extracellular matrix (ECM). Type II cell-ECM interactions are bidirectional; they involve matrix-mediated modulation of type II cell differentiation, as well as cellular synthesis and deposition of ECM components. The present experiments examine the kinetics of accumulation of newly synthesized proteins in cell and matrix fractions from primary cultures of type II pneumocytes. Cycloheximide-sensitive incorporation of [3H]leucine into total protein of both the cell and ECM fractions was linear for 24–30 h, when steady-state labeling was reached and maintained to at least day 8. Over this interval, the cells enlarged but did not divide. Newly synthesized proteins recovered in the matrix fraction averaged 1–2% of those in the cells. Relative rates of radiolabeling of matrix proteins peaked at culture day 2 and increased in the absence of serum. In short-pulse studies, initial rates of protein synthesis were equal on culture days 1 and 3; this suggested that the steady-state labeling kinetics above reflected protein turnover. This was supported by rapid loss of radioactivity from the ECM after fresh type II cells were seeded on a prelabeled, cell-free matrix surface. Fresh or conditioned Dulbecco's modified Eagle's medium containing 10% fetal calf serum had little effect on matrix stability. These results demonstrate regulated deposition and turnover of a complex ECM by type II cells and provide a basis for further investigations of factors that control these processes.

Adrenal hormone regulation of fibronectin synthesis by type II pulmonary epithelial cells

1997 ◽  
Vol 273 (1) ◽  
pp. L86-L92
Author(s):  
S. E. Dunsmore ◽  
Y. C. Lee ◽  
D. E. Rannels
Keyword(s):  
Extracellular Matrix ◽  
Epithelial Cells ◽  
Cell Phenotype ◽  
Type Ii Cells ◽  
Mrna Levels ◽  
Hormone Regulation ◽  
Type Ii ◽  
Adrenal Hormone ◽  
Pulmonary Epithelial Cells ◽  
Type Ii Cell

Previous work suggested an association between changes in the alveolar extracellular matrix and epithelial cell growth in lungs of adrenalectomized rats in vivo. Other studies demonstrated that adrenal hormones modulate extracellular matrix synthesis by type II pulmonary epithelial cells in vitro. Adrenal hormone regulation of type II cell fibronectin synthesis was thus examined. Fibronectin synthesis was quantitated by immunoprecipitation of the metabolically labeled molecule from cells, extracellular matrix, and culture medium. On day 1 of primary culture, synthesis of matrix fibronectin by type II cells isolated from the lungs of adrenalectomized animals was more than twice that by cells isolated from control rats. Adrenalectomy elevated steady-state fibronectin mRNA levels in primary isolates of type II cells cultured for 1 or 3 days. These results suggest that altered fibronectin synthesis and deposition into the extracellular matrix accompany changes in type II cell phenotype that occur after adrenalectomy.

Synthesis of fibronectin and laminin by type II pulmonary epithelial cells

1996 ◽  
Vol 270 (2) ◽  
pp. L215-L223 ◽  
Author(s):  
S. E. Dunsmore ◽  
Y. C. Lee ◽  
C. Martinez-Williams ◽  
D. E. Rannels
Keyword(s):  
Extracellular Matrix ◽  
Epithelial Cells ◽  
Primary Culture ◽  
Messenger Rna ◽  
Type Ii ◽  
Matrix Deposition ◽  
Pulmonary Epithelial Cells ◽  
The Matrix ◽  
Average Proportion ◽  
Type Ii Cell

Previous investigations demonstrated that type II pulmonary epithelial cells regulate extracellular matrix deposition as a function of time in primary culture. In those studies, the matrix fraction was analyzed as a whole. The present work focused on two components of the type II cell matrix, fibronectin and laminin. These glycoproteins have differing effects on differentiation of type II cells in primary culture. Fibronectin synthesis was quantitated between day 1 and day 6 in the cells, matrix, and medium; laminin synthesis was quantitated only in the cells. Although total fibronectin synthesis was regulated as a function of time in culture, reaching its greatest value on day 2, the average proportion of newly synthesized fibronectin in the cells (35%), medium (50%), and matrix (15%) remained constant over a 6-day interval. Between day 2 and day 6, the relative abundance of fibronectin messenger RNA increased 6.5-fold. Rates of cellular laminin synthesis did not vary with time in culture. These results support a role for differential regulation of fibronectin and laminin synthesis to determine the composition of the type II cell extracellular matrix.

Turnover of extracellular matrix by type II pulmonary epithelial cells

1995 ◽  
Vol 268 (2) ◽  
pp. L336-L346 ◽  
Author(s):  
S. E. Dunsmore ◽  
D. E. Rannels
Keyword(s):  
Extracellular Matrix ◽  
Epithelial Cells ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Alveolar Epithelium ◽  
Kinetic Studies ◽  
Type Ii Cells ◽  
Type Ii ◽  
Pulmonary Epithelial Cells ◽  
Matrix Stability

Rat type II pulmonary epithelial cells synthesize and assemble a multicomponent extracellular matrix (ECM) which can modulate cellular differentiation in primary culture. This study defines turnover of the type II cell matrix. Turnover kinetics were analyzed in two types of pulse-chase protocols based on loss of radioactive ECM components. To estimate turnover of previously synthesized ECM, type II cells were plated on extracted matrix that was radiolabeled 2, 3, or 6 days; alternatively, ECM was radiolabeled in pulse-chase experiments to measure turnover by the same cells that synthesized the matrix. Rapid initial rates of ECM turnover were evident in both cases. While overall matrix stability appeared to change with culture time, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed a similar spectrum of proteins in the ECM over the course of kinetic studies. The results reveal rapid turnover of ECM by type II cells and suggest that matrix stability may be regulated. These observations provide a basis for future investigations of the physiological significance of turnover of individual ECM components by the alveolar epithelium.

Roles of SP-A, SP-B, and SP-C in modulation of lipid uptake by pulmonary epithelial cells in vitro

1996 ◽  
Vol 270 (1) ◽  
pp. L69-L79 ◽  
Author(s):  
A. D. Horowitz ◽  
B. Moussavian ◽  
J. A. Whitsett
Keyword(s):  
Epithelial Cells ◽  
Lipid Vesicles ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lipid Uptake ◽  
3T3 Cells ◽  
Alveolar Cell ◽  
Pulmonary Epithelial Cells ◽  
Nih 3T3

The effects of the surfactant proteins (SP)-A, SP-B, and SP-C on binding and endocytosis of fluorescently labeled lipid vesicles were studied in rat type II epithelial cells and in MLE-12 cells, a pulmonary adenocarcinoma cell line with alveolar cell characteristics. Incorporation of SP-C in lipid vesicles markedly stimulated binding to the cell membrane at 4 degrees C and endocytosis of lipids at 37 degrees C. SP-C enhanced lipid uptake in MLE-12 cells, type II cells, and NIH 3T3 cells. SP-B stimulated lipid uptake in MLE-12 cells, but to a lesser degree. SP-B decreased the amount of lipid uptake stimulated by SP-C, SP-A did not increase endocytosis of lipids by MLE-12 cells or type II cells, but aggregates of lipid were observed associated with the cell surface in the presence of SP-A. Maintenance of active surfactant in the lung may be achieved through the selective uptake and degradation of surfactant subfractions depleted in SP-A and SP-B.

Extracellular matrix fibronectin alters connexin43 expression by alveolar epithelial cells

2001 ◽  
Vol 280 (4) ◽  
pp. L680-L688 ◽  
Author(s):  
Andrea I. Alford ◽  
D. Eugene Rannels
Keyword(s):  
Extracellular Matrix ◽  
Epithelial Cells ◽  
Gap Junction ◽  
Primary Culture ◽  
Alveolar Epithelial Cells ◽  
Dependent Manner ◽  
Type Ii ◽  
Cx43 Expression ◽  
Cx43 Protein ◽  
Alveolar Epithelial

Alveolar type II epithelial cells undergo phenotypic changes and establish gap junction intercellular communication as they reach confluence in primary culture. The pattern of gap junction protein (connexin) expression changes in parallel. Although connexin (Cx)43 mRNA and protein increase significantly by culture day 2, Cx26 and Cx32 expression decline. Along with increasing Cx43 expression, the cells assemble fibronectin derived both from serum in the culture medium and from de novo synthesis into the extracellular matrix (ECM). The present studies indicate that this ECM regulates Cx43 expression. Culture of type II cells in DMEM containing 8–10% fetal bovine serum (FBS) promotes assembly of a fibronectin-rich ECM that stimulates expression of both Cx43 mRNA and protein. Although Cx43 protein expression increased in response to FBS in a dose-dependent manner, fibronectin also elevated Cx43 protein in the absence of FBS. Anti-fibronectin antibody significantly reduced the serum-dependent increase in Cx43 expression. These results support the premise that fibronectin in the ECM contributes to the regulation of Cx43 expression by alveolar epithelial cells in primary culture.

Functional IL-2 receptors are expressed by rat lung type II epithelial cells

1997 ◽  
Vol 273 (3) ◽  
pp. L495-L503 ◽  
Author(s):  
O. Lesur ◽  
K. Arsalane ◽  
J. Berard ◽  
J. P. Mukuna ◽  
A. J. de Brum-Fernandes ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Thymidine Incorporation ◽  
Primary Cultures ◽  
Epithelial Cell Line ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Gamma Chain ◽  
Ifn Gamma

Interferon (IFN)-gamma-induced inhibition of type II epithelial cell thymidine incorporation (45% decrease vs. control) was restored by cocultures with mitogen-activated peripheral blood mononuclear cells (PBMC) and conditioned media (CM) from mitogen-activated PBMC. Successive exposure of type II cells to IFN-gamma and interleukin (IL)-2 produced similar alterations in thymidine incorporation. Given that IL-2 is a powerful pleiotropic cytokine produced by lymphoid and myeloid cells, the presence of IL-2 receptors (IL-2R) was assessed in primary cultures of rat type II pneumocytes (TIIP) and the nontransformed alveolar type II epithelial cell line L2. The presence of IL-2R membrane protein on rat type II cells was established by immunodetection assays. The expression of all three murine IL-2R alpha-, beta-, and gamma-chain RNA transcripts in primary TIIP cultures and L2 cells was highlighted by reverse transcriptase-polymerase chain reaction analysis. Overall, these experiments demonstrate, for the first time, that type II epithelial cells can express functional IL-2R, confirming TIIP as a potential "partner" in the lung immune system. Consequently, it can be speculated that TIIP are new cellular targets for lymphokines using (IL-2R) gamma-chain-bearing receptors in lung distal air-spaces.

Parathyroid hormone-related protein, an autocrine regulatory factor in alveolar epithelial cells

1996 ◽  
Vol 270 (3) ◽  
pp. L353-L361 ◽  
Author(s):  
R. H. Hastings ◽  
D. Summers-Torres ◽  
T. C. Cheung ◽  
L. S. Ditmer ◽  
E. M. Petrin ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Primary Cultures ◽  
A549 Cells ◽  
Alveolar Epithelial Cells ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Epithelial ◽  
Parathyroid Hormone Related Protein ◽  
Pthrp Receptor

Alveolar epithelial cells in vivo, primary cultures of adult rat type II cells, and human A549 alveolar carcinoma cells express parathyroid hormone-related protein (PTHrP). Here we demonstrated that type II cells and A549 cells also express the PTHrP receptor and that they exhibit differentiation-related responses to the amino-terminal PTHrP fragment, PTHrP-(1-34). PTHrP receptor expression in A549 cells was shown by detection of a 0.3-kb reverse transcriptase polymerase chain reaction product formed by primers specific for PTHrP receptor. In situ hybridization studies localized the site of production of PTHrP and PTHrP receptor mRNA in rat lung cells with morphology and location typical of type II cells. Primary cultures of such type II cells also expressed PTHrP receptor mRNA. Incubation with PTHrP-(1-34) stimulated disaturated phosphatidylcholine (DSPC) synthesis in A549 cells and increased the release of newly synthesized DSPC by cultured type II cells and A549 cells. In addition, PTHrP-(1-34) increased the number of lamellar bodies per type II cell and increased their expression of alkaline phosphatase in a dose-dependent manner. Thus PTHrP-(1-34) promoted a differentiated type II cell phenotype. Since cultured type II cells, alveolar epithelial cells in vivo, and A549 cells express PTHrP and the PTHrP receptor, PTHrP-(1-34) may be an autocrine regulatory factor in type II cells and lung cancer cells.

Alveolar type II cells synthesize hydrophobic cell-associated proteoglycans with multiple core proteins

1992 ◽  
Vol 263 (3) ◽  
pp. L348-L356 ◽  
Author(s):  
W. M. Maniscalco ◽  
M. H. Campbell
Keyword(s):  
Extracellular Matrix ◽  
Cell Surface ◽  
Heparan Sulfate ◽  
Core Protein ◽  
Primary Cultures ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
Core Proteins

Type II alveolar epithelial cells interact with the extracellular matrix via cell surface receptors for matrix ligands. Cell surface proteoglycans, which are hydrophobic due to their membrane insertion domains, are one of several classes of molecules that may be receptors for matrix ligands. To analyze the hydrophobic proteoglycans synthesized by adult alveolar type II cells, we labeled these cells with 35SO4 and [3H]leucine in short-term primary cultures. Cell-associated hydrophobic proteoglycans and culture medium-derived proteoglycans were purified and characterized. Both the hydrophobic proteoglycans and medium-derived proteoglycans, which were not hydrophobic, had mainly heparan sulfate glycosaminoglycans. Analysis of core proteins of the hydrophobic proteoglycans showed three proteins, 47, 65, and 90 kDa. The 47- and 65-kDa core proteins were substituted only with heparan sulfate chains. The 90-kDa core protein was seen only after digestion with both heparitinase and chondroitin ABC lyase, suggesting it was a hybrid having both heparan sulfate and chondroitin-dermatan sulfate chains. These findings were confirmed by iodination of the core proteins. The hydrophobic cell-associated proteoglycans inserted into artificial liposomes, whereas the medium-derived molecules did not. These data document heterogeneity in core protein and glycosaminoglycan chains among hydrophobic proteoglycans synthesized in vitro by adult alveolar type II cells. These molecules may have diverse functions in regulating type II cell interaction with the extracellular matrix.

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