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Deterding RR, Jacoby CR, Shannon JM. Acidic fibroblast growth factor and keratinocyte growth factor stimulate fetal rat pulmonary epithelial growth. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:L495-505. [PMID: 8897895 DOI: 10.1152/ajplung.1996.271.4.l495] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have shown that pulmonary epithelial growth and differentiation can occur if pulmonary mesenchyme is replaced with a mixture of growth factors [total growth medium (TGM)] that consists of adult rat bronchoalveolar lavage fluid, insulin, epidermal growth factor (EGF), cholera toxin (CT), acidic fibroblast growth factor (aFGF), and fetal bovine serum. In the present study, we have defined the importance of specific components of TGM. Day 14 fetal rat distal lung epithelium, devoid of mesenchyme, was enrobed in growth factor-depleted Matrigel and cultured for 5 days in various soluble factors. We found that deleting aFGF or CT from TGM significantly reduced DNA synthesis. Epithelial proliferation was not significantly different when keratinocyte growth factor (KGF) replaced aFGF in TGM. KGF, however, required the presence of a basal medium containing CT, insulin, and serum for optimal proliferation. We then added specific growth factors to the basal medium and showed that aFGF and KGF were more potent mitogens than EGF, transforming growth factor-alpha, and hepatocyte growth factor. Additionally, basal medium + KGF also allowed progression to a distal alveolar phenotype. We conclude that aFGF and KGF may be important mediators in epithelial-mesenchymal interactions.
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Sugahara K, Rubin JS, Mason RJ, Aronsen EL, Shannon JM. Keratinocyte growth factor increases mRNAs for SP-A and SP-B in adult rat alveolar type II cells in culture. THE AMERICAN JOURNAL OF PHYSIOLOGY 1995; 269:L344-50. [PMID: 7573468 DOI: 10.1152/ajplung.1995.269.3.l344] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The production of pulmonary surfactant, a complex of phospholipids and lung-specific surfactant proteins, is a primary function of alveolar type II cells. Although previous studies have demonstrated a role for cell-extracellular matrix interactions and normal cell shape in the maintenance of differentiated function in primary cultures of adult rat type II cells, a positive role for growth factors in surfactant protein gene expression in isolated normal adult type II cells has not been reported. In the present study, we have examined the effects of a panel of hormones, growth factors, and cytokines on the expression of mRNAs for surfactant proteins A, B, and C (SP-A, SP-B, and SP-C). Our results show that keratinocyte growth factor (KGF) induced a two- to threefold increase in steady-state levels of mRNAs for SP-A and SP-B, but had no effect on or decreased SP-C mRNA. The increase in SP-A mRNA was accompanied by an increase in SP-A protein. The effects of KGF were both dose and time dependent, and they could be neutralized by a monoclonal antibody against KGF. The effects of KGF were mimicked by acidic fibroblast growth factor, which will bind the KGF receptor. We conclude that KGF can support differentiation of alveolar type II cells as well as act as a mitogen, thus suggesting an important role for KGF in maintenance of the alveolar epithelium.
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Deterding RR, Shannon JM. Proliferation and differentiation of fetal rat pulmonary epithelium in the absence of mesenchyme. J Clin Invest 1995; 95:2963-72. [PMID: 7769139 PMCID: PMC295985 DOI: 10.1172/jci118004] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Previous studies have shown that pulmonary mesenchyme is required to maintain epithelial viability and to support branching morphogenesis and cytodifferentiation. We have examined whether pulmonary mesenchyme can be replaced by a medium containing a combination of soluble factors. Day 13-14 fetal rat distal lung epithelium was enzymatically separated from its mesenchyme, enrobed in EHS tumor matrix, and cultured for 5 d in medium containing concentrated bronchoalveolar lavage, EGF, acidic fibroblast growth factor, cholera toxin, insulin, and FBS (TGM), or in control medium containing only FBS. After 5 d in culture, marked growth and morphological changes occurred in epithelial rudiments cultured in TGM, whereas no changes were seen in controls. [3H]Thymidine incorporation and nuclear labeling indices during the last 24 h of culture confirmed that epithelial rudiments cultured in TGM had significant proliferative capacities. Evaluation of surfactant protein gene expression by Northern analysis, in situ hybridization, and immunocytochemistry demonstrated that distal lung epithelial differentiation progressed in TGM. Ultrastructural analysis demonstrated that fetal distal lung epithelium cultured in TGM contained lamellar bodies and deposited a basal lamina. These results are the first demonstration that sustained proliferation and differentiation of glandular stage distal pulmonary epithelium can proceed in the absence of mesenchyme.
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Danto SI, Shannon JM, Borok Z, Zabski SM, Crandall ED. Reversible transdifferentiation of alveolar epithelial cells. Am J Respir Cell Mol Biol 1995; 12:497-502. [PMID: 7742013 DOI: 10.1165/ajrcmb.12.5.7742013] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Alveolar epithelial type II (AT2) cells have been thought to be the progenitors of terminally differentiated type I (AT1) cells in the adult animal in vivo. In this study, we used an AT1 cell-specific monoclonal antibody (mAb VIII B2) to investigate expression of the AT1 cell phenotype accompanying reversible changes in expression of the AT2 cell phenotype. AT2 cells were isolated and cultured either on attached collagen gels or on gels detached 1 or 4 days after plating and maintained thereafter as floating gels. Monolayers on both attached and floating gels were harvested on days 4 and 8 and analyzed by electron microscopy for changes in morphology and binding of mAb VIII B2. Results indicate that: (1) alveolar epithelial cells (AEC) on attached gels develop characteristics of the AT1 cell phenotype, (2) AEC on gels detached on day 1 maintain features of the AT2 cell phenotype (and do not react with mAb VIII B2), and (3) the expression of AT1 cell phenotypic traits seen by day 4 on attached gels is reversed after detachment. We conclude that commitment to the AT1 and AT2 cell lineages requires continuous regulatory input to maintain the differentiated states, and that transdifferentiation between AT2 and AT1 cells may be reversible.
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Shannon JM. Induction of alveolar type II cell differentiation in fetal tracheal epithelium by grafted distal lung mesenchyme. Dev Biol 1994; 166:600-14. [PMID: 7813779 DOI: 10.1006/dbio.1994.1340] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Normal branching morphogenesis and cytodifferention of the lung require a specific interaction between the epithelial rudiment and pulmonary mesenchyme. Previous studies in the mouse have shown glandular stage pulmonary mesenchyme can elicit a lung-like pattern of branching morphogenesis when grafted onto tracheal epithelium of the same age that has been denuded of its own mesenchyme. We have examined whether are not this pattern of branching is accompanied by changes in epithelial cytodifferentiation. Purified pulmonary mesenchyme was isolated from the distal tips of day 13-14 fetal rat lungs and grafted onto a stretch of tracheal epithelium from which the mesenchyme had been removed. The grafts were cultured on semisolid 0.5% agarose in Waymouth's medium containing 10% serum for 5 days and then for an additional 2 days in the same medium containing 10(-6) M cortisol. Unoperated or operated-ungrafted tracheae and intact lung explants served as controls. Grafting distal tip pulmonary mesenchyme onto the tracheal epithelium induced a pattern of branching identical to that seen in control lung explant cultures, while ungrafted control tracheal cultures formed cystic structures. Light microscopy of the induced tracheal epithelium showed that the constituent cells exhibited a morphology virtually identical to cells in control lung explants. Ultrastructural analysis demonstrated that the induced tracheal epithelial cells contained lamellar inclusion bodies, and the lumina of the induced acinar structures contained tubular myelin figures. Reverse transcription polymerase chain reaction analysis of the induced tracheae revealed the presence of mRNAs for surfactant protein A (SP-A) and SP-B, as well as SP-C, which is a specific marker for type II cell differentiation in the adult rat. Control tracheal cultures contained mRNAs only for SP-A and SP-B. Immunocytochemistry demonstrated that many cells within the induced tracheal epithelium were positive for SP-A and SP-C proteins. Further studies demonstrated that the ability of mesenchyme to induce tracheal epithelium varied within the pulmonary tree, and that the competence of the tracheal epithelium to respond to the influence of distal tip mesenchyme was temporally restricted. Our results demonstrate that pulmonary mesenchyme can act instructively on the tracheal epithelium to induce a program of type II cell differentiation.
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Mason RJ, Leslie CC, McCormick-Shannon K, Deterding RR, Nakamura T, Rubin JS, Shannon JM. Hepatocyte growth factor is a growth factor for rat alveolar type II cells. Am J Respir Cell Mol Biol 1994; 11:561-7. [PMID: 7524567 DOI: 10.1165/ajrcmb.11.5.7524567] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Proliferation of alveolar type II cells is thought to be critical for restoration of gas exchange units after diffuse alveolar damage. However, the factors that regulate type II cell proliferation are not well understood. Hepatocyte growth factor (HGF) is a potentially important mitogen because it causes epithelial cells but not fibroblasts to proliferate and is found in the lung. We used rat alveolar type II cells in primary culture to demonstrate that HGF stimulates DNA synthesis in a concentration-dependent manner. The half maximal effect on stimulation of thymidine incorporation was less than 1 ng/ml. By autoradiography, HGF increased nuclear labeling from 1.3% of type II cells with medium alone to 9.4% with 5 ng/ml HGF. During this time, HGF modestly increased cell number in comparison to control media. However, in an assay of colony formation in low-density cultures, HGF did not consistently increase colony formation by alveolar type II cells and was less effective than acidic fibroblast growth factor or bronchoalveolar lavage fluid in this assay. The receptor for HGF (c-met proto-oncogene) was expressed in rat type II cells and whole lung but not in macrophages. In contrast, the mRNA for HGF was detected in rat macrophages and lung but not in type II cells. However, HGF message was not detected in human alveolar macrophages under conditions in which the HGF message was detected in rat alveolar macrophages and in human fibroblasts. Hence, HGF is a potential paracrine growth factor for alveolar type II cells, but there may be important species differences in the relative level of expression.
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Deterding RR, Shimizu H, Fisher JH, Shannon JM. Regulation of surfactant protein D expression by glucocorticoids in vitro and in vivo. Am J Respir Cell Mol Biol 1994; 10:30-7. [PMID: 8292379 DOI: 10.1165/ajrcmb.10.1.8292379] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
SP-D is a recently described lung-associated protein that is produced by alveolar type II cells and may function in pulmonary host defenses. Since little is known regarding the hormonal regulation of SP-D, and since the other surfactant proteins (SP-A, SP-B, and SP-C) are known to be regulated by glucocorticoids, we sought to determine the effects of glucocorticoids on SP-D mRNA and protein expression, both in vitro and in vivo, in the fetal rat lung. In vitro experiments were performed on lung explants from fetuses on gestational day 15 or 18. Explants were cultured in serum-free conditions with or without hydrocortisone for 3 days. SP-D mRNA expression was evaluated by Northern blot analysis. SP-D protein expression was analyzed using a polyclonal antibody against SP-D and standard immunohistochemical techniques. The expression of SP-D mRNA increased in fetal day 15 explants but remained unchanged in fetal day 18 explants cultured without the addition of hydrocortisone, compared with in vivo controls. The addition of hydrocortisone resulted in increases in SP-D mRNA expression at both gestational ages. This pattern of SP-D mRNA expression was compared with the expression of the other surfactant proteins and found to be most similar to that of SP-B. In vivo experiments were performed using maternal administration of dexamethasone (1 mg/kg) or an equal volume of saline on fetal days 15, 16, and 17 or on fetal day 17 with sacrifice on fetal day 18.(ABSTRACT TRUNCATED AT 250 WORDS)
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Leslie CC, McCormick-Shannon K, Mason RJ, Shannon JM. Proliferation of rat alveolar epithelial cells in low density primary culture. Am J Respir Cell Mol Biol 1993; 9:64-72. [PMID: 8338678 DOI: 10.1165/ajrcmb/9.1.64] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Alveolar type II cells proliferate to restore the alveolar epithelium after lung injury and differentiate into type I epithelial cells. A variety of factors promote rat type II cell DNA synthesis in vitro; however, only low levels of proliferation occur when type II cells are cultured at high density. We plated type II cells at low density to determine if those growth factors that stimulate thymidine incorporation also stimulate low density proliferation. Type II cells were plated at 1 x 10(3) cells/cm2 in Dulbecco's modified Eagle's medium containing 2% fetal bovine serum, cholera toxin, insulin, epidermal growth factor, acidic fibroblast growth factor (aFGF), and concentrated bronchoalveolar lavage fluid from normal rats. By 7 days, numerous colonies had grown out that exhibited an epithelial morphology and stained positively for cytokeratin. The cell number at day 7 in the presence of the combined factors was 5.9 x 10(3) (+/- 0.6 x 10(3)) cells/cm2 (n = 4). There was no colony formation in the absence of fetal bovine serum. The addition of linoleic acid to serum-free medium containing all the growth supplements was found to partially restore colony formation. When aFGF or lavage fluid was omitted from the culture medium, colony formation was dramatically reduced. The colonies lacked characteristics of differentiated type II cells, which was anticipated since these cells were cultured on tissue culture plastic. To see if these cells could express differentiated functions, we maintained the colonies under growth conditions, removed them from the plastic substratum, and then replated them on EHS matrix.(ABSTRACT TRUNCATED AT 250 WORDS)
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Kalina M, Mason RJ, Shannon JM. Surfactant protein C is expressed in alveolar type II cells but not in Clara cells of rat lung. Am J Respir Cell Mol Biol 1992; 6:594-600. [PMID: 1591008 DOI: 10.1165/ajrcmb/6.6.594] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The expression of the surfactant-associated proteins in bronchiolar cells remains to be defined. We used in situ hybridization to identify sites of message expression of the surfactant-associated proteins A, B, and C (SP-A, SP-B, and SP-C) in adult and fetal rat lung. The expression of these messages by in situ hybridization was also compared with the localization of SP-A by immunocytochemistry. The localization of SP-A was used to identify type II cells and nonciliated bronchiolar epithelial (Clara) cells in these sections. The cRNA antisense probes for SP-A, SP-B, and SP-C appeared to hybridize over type II cells. Sense probes showed no localization or apparent specific hybridization. Messages for both SP-A and SP-B were also found in nonciliated bronchiolar epithelial (Clara) cells. However, no message for SP-C was observed in these cells. Clara cells from terminal to large bronchioles lacked detectable mRNA for SP-C. Expression of surfactant protein mRNAs was not detectable in type I cells, alveolar macrophages, interstitial cells, or vascular cells. Similarly, in fetal rat lung the messages for SP-A and SP-B but not SP-C were detected in bronchiolar cells. We conclude that rat Clara cells do not express SP-C mRNA, and thus SP-C can be regarded as a specific marker for rat type II cells.
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Shannon JM, Jennings SD, Nielsen LD. Modulation of alveolar type II cell differentiated function in vitro. THE AMERICAN JOURNAL OF PHYSIOLOGY 1992; 262:L427-36. [PMID: 1566858 DOI: 10.1152/ajplung.1992.262.4.l427] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have investigated whether the loss of differentiated function observed in adult rat alveolar type II cells cultured on a substratum that promotes cell spreading and flattening represents a reversible phenotypic change. Cells were cultured for 4 and 8 days in association with fetal rat lung fibroblast feeder layers on either attached collagen gels, which promote the loss of differentiated function, or on floating collagen gels, which support differentiation. A fifth group of cultures were maintained as attached gels for 4 days, then detached and cultured as floating gels for the remaining 4 days. Expression of mRNAs for surfactant proteins A, B, and C, patterns of phospholipid biosynthesis, rates and patterns of protein synthesis, and cell morphology were evaluated as markers of differentiation. Without exception, detaching the gels after 4 days in culture resulted in significant recovery of differentiated characteristics, demonstrating that type II cells modulate differentiated function in response to the culture environment. The results are discussed in relation to the importance of normal cell architecture to normal cell function and to the possible in vitro progression of type II cells to type I cells.
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Fisher JH, McCormack F, Park SS, Stelzner T, Shannon JM, Hofmann T. In vivo regulation of surfactant proteins by glucocorticoids. Am J Respir Cell Mol Biol 1991; 5:63-70. [PMID: 1878253 DOI: 10.1165/ajrcmb/5.1.63] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Surfactant proteins have key roles in regulating surfactant secretion, in recycling, and in the assembly of the surfactant monolayer but little is known about their regulation in vivo. Surfactant proteins SP-A, SP-B, and SP-C have been shown to be upregulated by glucocorticoids in vitro, but the role of glucocorticoids in the physiologic regulation of surfactant protein synthesis remains unknown. We have studied the effects of exogenously administered glucocorticoids on the regulation of steady-state surfactant protein mRNA accumulation. We have also studied the effects of adrenalectomy on the accumulation of the surfactant protein mRNAs. Surfactant protein genes appear to have quantitatively different responses to exogenously administered glucocorticoids, with SP-C mRNA increasing at the lowest dose, SP-A and SP-B mRNA increasing in response to similar glucocorticoids doses but with SP-B yielding the highest maximum response. Adrenalectomy, however, does not alter surfactant protein mRNA levels. These observations support a minor role for glucocorticoids in maintaining the steady-state accumulation of surfactant protein mRNA. Adrenalectomy decreases total pulmonary SP-A when compared to sham-operated animals in the absence of changes in its mRNA. Therefore, glucocorticoids may have translational or post-translational effects that regulate total pulmonary SP-A accumulation, but the effects appear to be minor. These findings support a potential role for the adrenal in the pulmonary response to stress and demonstrate for the first time differential accumulation of the surfactant protein mRNAs to glucocorticoids in vivo.
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Schellhase DE, Shannon JM. Effects of maternal dexamethasone on expression of SP-A, SP-B, and SP-C in the fetal rat lung. Am J Respir Cell Mol Biol 1991; 4:304-12. [PMID: 2015097 DOI: 10.1165/ajrcmb/4.4.304] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Prenatal administration of glucocorticoids has been shown to enhance surfactant production in the fetus. Since the surfactant proteins play an important role in surfactant function and secretion, we wished to determine the effects of maternal glucocorticoid administration on their fetal expression and appearance. Daily dexamethasone (DEX) (1 mg/kg/day) or 0.9% saline was administered to timed-pregnant rats on gestational days 14 through 16 or on day 16 with sacrifice on day 17 (term day 22), and on gestational days 14 through 18, or days 16 through 18, or day 18 with sacrifice on day 19. SP-A content was determined in lung homogenates from treated and control male and female fetal rats by an enzyme-linked in lung homogenates from treated and control male and female fetal rats by an enzyme-linked immunosorbent assay. The abundance of mRNAs for SP-A, SP-B, and SP-C per fixed amount of total cellular RNA was also determined in lungs from treated and control male and female fetal rats by Northern blot analysis. In litters sacrificed on day 17, DEX administered on days 14 through 16 and on day 16 resulted in significant increases in SP-A content. Expression of SP-A mRNA, which was not detectable in control fetuses on day 17, became clearly apparent after either 1 or 3 d of DEX treatment. The abundance of mRNAs for SP-B and SP-C also increased in day-17 fetuses after either 1 or 3 d of DEX treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
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McCormack FX, Fisher JH, Suwabe A, Smith DL, Shannon JM, Voelker DR. Expression and characterization of rat surfactant protein A synthesized in Chinese hamster ovary cells. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1087:190-8. [PMID: 2171680 DOI: 10.1016/0167-4781(90)90204-f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Rat surfactant protein A (SP-A) was expressed in a Chinese hamster ovary (CHO-K1) cell line and characterized for biologic activity using assays for receptor binding and modulation of phospholipid secretion from isolated type II cells. The CHO-K1 cell line was cotransfected with separate plasmids encoding for the rat SP-A, dihydrofolate reductase and neomycin phosphotransferase, respectively. Antibiotic (Geneticin-G418)-resistant transformants were screened by ELISA for the secretion of recombinant SP-A into the media. Northern analysis of the transfected cell lines demonstrated the expression of both 1.6 kb and 0.9 kb mRNA species for SP-A, consistent with the proposed differential polyadenylation of the primary transcript. Amplification with methotrexate resulted in a dose-dependent increase in mRNA for SP-A and a 20-fold increase in the production of recombinant SP-A relative to untreated cells. Maximum production of SP-A was 370 micrograms of SP-A/l of media in a 4-day incubation. Recombinant SP-A was purified from the serum-free media of large scale cultures of transfected, amplified CHO cells by affinity chromatography on mannose-Sepharose. The recombinant SP-A migrated similarly to native SP-A by NaDodSO4-PAGE analysis under reducing and nonreducing conditions and under reducing conditions after digestion with N-glycanase. Recombinant SP-A effectively competed with 125I-native SP-A for binding to the high affinity receptor for SP-A on isolated plasma membranes from rat alveolar type II cells. The recombinant SP-A was as effective as native SP-A in the inhibition of secretion of phospholipid from isolated type II cells. We conclude that recombinant rat SP-A produced in Chinese hamster ovary cells is physically and functionally similar to native rat SP-A.
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Kawada H, Shannon JM, Mason RJ. Improved maintenance of adult rat alveolar type II cell differentiation in vitro: effect of serum-free, hormonally defined medium and a reconstituted basement membrane. Am J Respir Cell Mol Biol 1990; 3:33-43. [PMID: 2363935 DOI: 10.1165/ajrcmb/3.1.33] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We have developed a serum-free, hormonally defined medium for maintenance of differentiation of adult type II cells cultured on Engelbreth-Holm-Swarm (EHS) tumor basement membrane gels. This defined medium consists of 1:1 (vol/vol) mixture of Ham's F12 and Dulbecco's modified Eagle's media supplemented with insulin, dibutyryl cyclic AMP, hydrocortisone, epidermal growth factor, selenium, and albumin/linoleic acid complex. Compared to cells cultured on EHS gels in serum-supplemented medium, type II cells cultured on EHS gels in this defined medium showed increased acetate incorporation into total lipids (10-fold) and an increase in the relative percentage of acetate incorporated into phosphatidylcholine (PC) (87.8 +/- 0.4% versus 78.5 +/- 1.0% [mean +/- SE]; P less than 0.01), saturated phosphatidylcholine (SPC) (61.4 +/- 0.5% versus 55.2 +/- 0.9%; P less than 0.01), and phosphatidylglycerol (PG) (5.3 +/- 0.3% versus 0.8 +/- 0.1%; P less than 0.01) and decreased acetate incorporation into neutral lipids (9.7 +/- 0.8% versus 62.6 +/- 1.9%; P less than 0.01). No response to this defined medium was seen when type II cells were cultured on tissue culture plastic. Type II cells cultured on EHS gels in serum-supplemented medium for 4 d had numerous neutral lipid droplets in their cytoplasm. In contrast, neutral lipid droplets were not commonly observed within the cytoplasm of the cells cultured in serum-free, hormonally defined medium on EHS gels. This morphologic finding was consistent with the result that cells cultured in serum-supplemented medium significantly increased the relative percentage of acetate incorporated into neutral lipids. These data indicate that adult type II cells cultured on a reconstituted basement membrane (EHS gels) can be maintained in synthetic culture medium without serum. These culture conditions permit the expression of a pattern of differentiated phospholipid biosynthesis and cell morphology more similar to normal type II cell differentiation.
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Glode LM, Shannon JM, Malik N, Nett T. Protection of rat spermatogenic epithelium from damage induced by procarbazine chemotherapy. Br J Cancer 1990; 62:61-4. [PMID: 2117966 PMCID: PMC1971720 DOI: 10.1038/bjc.1990.229] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Shannon JM, Emrie PA, Fisher JH, Kuroki Y, Jennings SD, Mason RJ. Effect of a reconstituted basement membrane on expression of surfactant apoproteins in cultured adult rat alveolar type II cells. Am J Respir Cell Mol Biol 1990; 2:183-92. [PMID: 2306374 DOI: 10.1165/ajrcmb/2.2.183] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Pulmonary surfactant, which is composed of phospholipids and three lung-specific apoproteins, is synthesized and secreted by alveolar type II cells. Previous work from this laboratory (Biochim. Biophys. Acta 1987; 931:143-156) has shown that cell-extracellular matrix interactions and cuboidal cell shape affect both the ultrastructural appearance and pattern of phospholipids synthesized by cultured rat type II cells. In the present study, we have examined the effects of cell-matrix interactions and cell shape on the ability of adult rat type II cells to express the surfactant apoproteins in culture. Isolated adult rat type II cells were cultured for 2, 4, and 8 days on either tissue culture plastic, on an extract of the Engelbreth-Holm-Swarm (EHS) tumor, or on laminin-coated plastic dishes. Expression of surfactant proteins A, B, and C (SP-A, SP-B, and SP-C) was evaluated by Northern analysis using specific rat cDNA probes for these mRNAs. SP-A content was determined by enzyme-linked immunosorbent assay using a polyclonal antibody raised against rat SP-A purified from lavage. Type II cells cultured on plastic dishes assumed an attenuated morphology soon after being placed in culture. Except for an occasional positive signal on day 2 of culture, these cells were uniformly negative for the presence of mRNA for SP-A, SP-B, or SP-C. Type II cells cultured on plastic did not contain SP-A. In contrast, type II cells cultured on EHS gels formed three-dimensional aggregates on the surface of the substratum; these aggregates were composed of polarized cells that had their apical surfaces directed inward. Type II cells cultured on this substratum showed a positive signal for mRNA for all three surfactant proteins; the abundance of these mRNAs, however, was significantly below that seen in freshly isolated type II cells. While the abundance of mRNA for SP-A and SP-B steadily increased with time in culture under these conditions, the abundance of SP-C mRNA decreased, suggesting that SP-C is regulated independently of SP-A and SP-B. These cultures were also positive for SP-A content, which increased with increasing time in culture. Type II cells cultured on laminin-coated dishes initially spread more slowly across the culture surface than cells on plastic, but were extremely attenuated by day 8 in culture. These cells contained neither SP-A, nor mRNA for any of the three surfactant proteins.(ABSTRACT TRUNCATED AT 400 WORDS)
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Edelson JD, Shannon JM, Mason RJ. Effects of two extracellular matrices on morphologic and biochemical properties of human type II cells in vitro. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1989; 140:1398-404. [PMID: 2817604 DOI: 10.1164/ajrccm/140.5.1398] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Previous observations have suggested that differentiated functions of adult rat type II alveolar cells are affected in part by cell-matrix interactions. We examined several aspects of differentiated adult human type II cells cultured on either bovine corneal endothelial cell extracellular matrix (BCECM) or matrix derived from the Englebreth-Holm-Swarm tumor (EHS). Compared to cells cultured on BCECM, adult human type II cells grown on EHS assumed a more cuboidal shape, had a more defined apical-basal polarity, and appeared to contain a greater number of lamellar bodies and neutral lipid inclusions. These cells also incorporated a greater percentage of [14C]acetate into saturated phosphatidylcholine (SPC) than did their counterparts grown on BCECM. In contrast, the relative incorporation of [14C]acetate into phosphatidylglycerol (PG) was lower in cells grown on EHS than cells cultured on BCECM. The histochemical stain for alkaline phosphatase was useful in identification of human type II cells. Alkaline phosphatase expression was elevated in cells cultured on EHS compared to those cultured on BCECM. These results suggest that maintenance of a differentiated morphology, lipid synthesis, and expression of alkaline phosphatase activity by primary cultures of adult human type II cells are also influenced by cell-matrix interactions. All markers of differentiated function of type II cells except synthesis of PG are better maintained on EHS than on BCECM. Under the conditions of these experiments, synthesis of SPC and PG appears to be independently regulated.
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Abstract
Content of the 26-38-kD surfactant apoprotein (SP-A) was determined in lung homogenates from fetal (17-21 d gestation), postnatal (1-28 d of life), and adult male and female rats by a double sandwich ELISA. Expression of mRNA for SP-A as well as the hydrophobic apoproteins, SP-B and SP-C, were also determined in lung homogenates from fetal and adult rats of both sexes by Northern blot analysis. SP-A was undetectable in fetal lungs on d 17 (day of birth = d 22) and barely detectable on d 18. On d 19 there was a 3- to 4-fold increase in SP-A content above d 18 levels. Between d 19 and 21 SP-A content significantly increased another 6- to 9-fold. SP-A content on the day of birth was not significantly different from that seen on gestational d 21. SP-A content decreased 35-40% between the day of birth and postnatal d 7. After the second postnatal week SP-A content gradually increased, reaching adult levels after d 28. No sex differences in SP-A content were observed during fetal or postnatal lung maturation. SP-A mRNA was first detected in fetal lungs on d 18 and increased in relative abundance until d 21, but remained below adult levels. Developmental changes in fetal lung SP-A content closely paralleled changes in fetal expression of SP-A mRNA. SP-B mRNA was also first detected on d 18, then increased in relative abundance to adult levels by d 20. SP-C mRNA was clearly detectable on d 17, then increased in relative abundance to adult levels by d 20-21. Unlike surfactant phospholipids, there are no apparent sex differences in the expression of any of the surfactant apoproteins during late gestation. The differences observed during fetal lung maturation in the time of onset and changes in relative abundance among the three apoprotein mRNA imply that their genes may be differentially regulated in the developing rat lung.
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Kawada H, Horiuchi T, Shannon JM, Kuroki Y, Voelker DR, Mason RJ. Alveolar type II cells, surfactant protein A (SP-A), and the phospholipid components of surfactant in acute silicosis in the rat. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1989; 140:460-70. [PMID: 2764382 DOI: 10.1164/ajrccm/140.2.460] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Silica instillation causes a massive accumulation of surfactant phospholipids and the appearance of hypertrophic type II cells in the rat. We have examined the metabolic consequences of silica instillation with a special emphasis on surfactant protein A (SP-A), the major glycoprotein of surfactant. Fourteen days after instillation of 10 mg of silica, the amount of phospholipids in lavage increased 14-fold and the amount of SP-A increased 10-fold. The phospholipid composition of lavage material from silica-treated animals was altered by a reduction in the percentage of phosphatidylglycerol and an increase in phosphatidylinositol. The percentage of saturated phosphatidylcholine did not change. Type II cells isolated from rats treated with silica could be separated into cells of normal size and of increased size by centrifugal elutriation. There was an increase in phospholipid and SP-A content in the larger type II cells isolated from silica-treated rats relative to type II cells from control rats (by 45% and 70%, respectively, when expressed per micrograms protein; p less than 0.01). Activities of the phospholipid biosynthetic enzymes cholinephosphate cytidyltransferase, lysophosphatidylcholine acyltransferase, and phosphatidylglycerol phosphate synthetase increased (nmol/min/mg cell protein) in the hypertrophic type II cells relative to type II cells from control rats (by 40%, 112%, and 95%, respectively, p less than 0.05). Incorporation of (1-14C)-acetate was also increased in hypertrophic type II cells relative to type II cells from control rats (by 43%, p less than 0.05). The only difference in the distribution of acetate incorporated into individual lipids was a slight increase in the percentage incorporated into phosphatidylinositol. Although the increase in phosphatidylcholine found in the lavage could be due to increased synthesis as reflected by the changes in enzymatic activity and rate of acetate incorporation, the reduction in phosphatidylglycerol in lavage and in type II cells could not be explained simply by a reduction in synthesis on the basis of available data. There was a marked increase in SP-A content in lavage and in type II cells isolated from silica-treated rats without a significant change in the relative abundance of SP-A mRNA. This dissociation of SP-A mRNA abundance and apoprotein content suggests that factors other than transcription may be important for the observed accumulation of SP-A in silica-treated rats. We conclude that the phospholipidosis and proteinosis that occur subsequent to silica instillation in the rat lung are not solely attributable to increase in the rates of synthesis of these components.
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Shannon JM, Dietz CK. Licensing health professionals: quality, competitive health care. THE JOURNAL OF STATE GOVERNMENT 1989; 62:121-3. [PMID: 10294465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
In licensing health professionals, states need to protect the public from unqualified practitioners without limiting price competition or consumer freedom. Attorneys general play a vital role in regulating professions and in protecting consumer interests in health care.
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Fisher JH, Shannon JM, Hofmann T, Mason RJ. Nucleotide and deduced amino acid sequence of the hydrophobic surfactant protein SP-C from rat: expression in alveolar type II cells and homology with SP-C from other species. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 995:225-30. [PMID: 2706272 DOI: 10.1016/0167-4838(89)90040-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Pulmonary surfactant lowers surface tension in the lung. Its deficiency leads to the severe physiologic abnormalities seen in the respiratory distress syndrome. The hydrophobic surfactant proteins, SP-B and SP-C, appear to be especially important in the surface-spreading characteristics of pulmonary surfactant. We report the nucleotide sequence of cDNA clones for rat SP-C and compare the deduced amino acid sequence for SP-C from several species. A highly conserved domain exists within the confines of mature human SP-C. An Eisenberg plot of this region predicts a membrane-associated helix. We also demonstrate by Northern analysis the tissue-specific expression of SP-C. A comparison of signal strength between total lung RNA and RNA derived from isolated type II cells supports the idea that most SP-C messenger RNA in total lung can be accounted for by that present in alveolar type II cells.
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Emrie PA, Shannon JM, Mason RJ, Fisher JH. cDNA and deduced amino acid sequence for the rat hydrophobic pulmonary surfactant-associated protein, SP-B. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 994:215-21. [PMID: 2920185 DOI: 10.1016/0167-4838(89)90296-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Pulmonary surfactant prevents collapse of lung alveoli by lowering surface tension at the air/liquid interface. The hydrophobic surfactant associated proteins SP-B and SP-C have been shown to be important in surfactant function and metabolism. A cDNA clone for rat SP-B was isolated and sequenced. Northern analysis showed mRNA for SP-B was present in whole lung and was greatly enriched in alveolar type II cells, but was not present in brain, kidney, spleen or liver. A full length transcript of the rat SP-B cDNA clone consists of 1536 bases and encodes an open reading frame of 376 amino acids. The predicted molecular mass of the primary translation product is 42 kDa and the predicted molecular mass of the mature protein is 8 kDa. Extensive homology exists between the rat sequence for SP-B and those reported for human and canine SP-B. The position of 25 cysteine residues has been extremely well preserved across all three species. An N-linked glycosylation site in the COOH region has been conserved across all three species. A search of the NIH database revealed homology between rat SP-B and the active site for the mouse contrapsin serum proteinase inhibitor.
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Kawada H, Shannon JM, Mason RJ. Improved maintenance of adult rat alveolar type II cell differentiation in vitro: effect of hydrocortisone and cyclic AMP. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 972:152-66. [PMID: 2847805 DOI: 10.1016/0167-4889(88)90114-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have examined the effect of hydrocortisone and cyclic AMP on the maintenance of lipid synthesis in primary cultures of adult rat alveolar type II cells. These hormones were tested in the presence of either 1% or 5% charcoal-stripped rat serum (CS-rat serum). The effect of substratum on responsiveness to these hormones was evaluated by comparing cells cultured for 4 days on tissue culture plastic, on floating type I collagen gels, on rat lung fibroblast feeder layers on floating collagen gels (floating feeder layers), and on Engelbreth-Holm-Swarm (EHS) tumor basement membrane gels. Type II cells cultured on floating feeder layers in medium containing 1% CS-rat serum and 10(-5) M hydrocortisone plus 0.5 mM dibutyryl cyclic AMP exhibited significantly increased incorporation of [14C]acetate into total lipids (238% of control). The hormone combination also increased the relative percentage of acetate incorporated into phosphatidylglycerol (PG; 7.3% versus 1.9%) and saturated phosphatidylcholine (PC; 43.6% versus 37.6%). The percentage of acetate incorporated into neutral lipids was significantly decreased by the addition of hormones (28.6% versus 70.0%). The addition of hydrocortisone and cyclic AMP to medium containing 5% CS-rat serum resulted in an increase in the relative incorporation of acetate into saturated PC (51.2% versus 46.4%), but had no effect on the relative incorporation of acetate into PG or on the incorporation of acetate into total lipids. Type II cells cultured on EHS gels in medium containing 1% CS-rat serum plus hydrocortisone and cyclic AMP showed increased acetate incorporation into total lipids (204% of control) and a relative decrease in the percentage of acetate incorporated into neutral lipids (16.9% versus 47.0%). The hormone combination also increased the relative incorporation of acetate into PG (4.4% versus 2.5%) and saturated PC (49.9% versus 42.1%). Hydrocortisone and cyclic AMP added to medium containing 5% CS-rat serum concentration increased the relative incorporation of acetate into saturated PC by type II cells on EHS gels, but these additions had no effect on acetate incorporation into PG. No responses to these soluble factors were seen when type II cells were cultured on floating type I collagen gels without feeder layers or on tissue culture plastic. These data indicate that there are positive interactions between substratum, soluble factors and serum in the maintenance of differentiated function of adult rat alveolar type II cells in vitro.
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Edelson JD, Shannon JM, Mason RJ. Alkaline phosphatase: a marker of alveolar type II cell differentiation. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1988; 138:1268-75. [PMID: 2462386 DOI: 10.1164/ajrccm/138.5.1268] [Citation(s) in RCA: 148] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In an effort to identify type II cells by a method independent of staining phospholipid inclusions, we evaluated a histochemical technique for alkaline phosphatase activity in normal rat lung, in freshly isolated type II cells, and in primary culture of type II cells. In the adult rat alveolus, alkaline phosphatase staining selectively identified type II cells, although nonciliated bronchiolar (Clara) cells and loose perivascular connective tissue also stained for alkaline phosphatase activity. In cell suspensions of type II cells and other dissociated lung cells, alkaline phosphatase staining correlated closely with the modified Papanicolaou technique and was particularly useful in distinguishing type II cells from alveolar macrophages. To determine if alkaline phosphatase was related to the differentiated phenotype of type II cells, we studied conditions known to affect other type II cell functions. When type II cells were cultured on plastic substrata, the intensity of alkaline phosphatase staining decreased with increasing time in culture. To quantitate the apparent decrease in alkaline phosphatase activity, we used a biochemical assay to study the expression of alkaline phosphatase by type II cells. The specific activity of alkaline phosphatase in type II cells declined with increasing time in tissue culture on plastic substrata. Alkaline phosphatase activity was maintained, however, by culturing cells on Englebreth-Holm-Swarm (EHS) tumor matrix. Cells that had reduced levels of alkaline phosphatase activity following 48 h of culture on plastic substrata could be "rescued" by removing them from the plastic substratum and reculturing them for 48 h on EHS matrix. Alkaline phosphatase activity was also increased by culturing type II cells in the presence of cAMP or sodium butyrate.(ABSTRACT TRUNCATED AT 250 WORDS)
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Shannon JM, Mason RJ, Jennings SD. Functional differentiation of alveolar type II epithelial cells in vitro: effects of cell shape, cell-matrix interactions and cell-cell interactions. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 931:143-56. [PMID: 3663713 DOI: 10.1016/0167-4889(87)90200-x] [Citation(s) in RCA: 168] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Alveolar type II epithelial cells rapidly lose characteristics of differentiated function when cultured on plastic dishes. We have attempted to circumvent this problem by culturing type II cells under conditions that might better reproduce their environment in vivo. Cell-matrix interactions were studied by culturing isolated adult rat type II cells on Engelbreth-Holm-Swarm (EHS) tumor basement membrane. Aggregates of type II cells formed on the surface of the matrix during 4 days in culture. Microscopic examination of these aggregates revealed cuboidal cells that retained more characteristics of differentiated type II cells than did cells cultured on plastic. Type II cells cultured on EHS matrix incorporated a higher percentage of acetate into phosphatidylcholine (PC) than did cells on plastic, and a higher percentage of this PC was saturated. Phosphatidylglycerol (PG) synthesis by these cells was no different from that seen in cells on plastic. The effects of cell-cell interactions and cell shape were evaluated by culturing type II cells on feeder layers that in turn were grown on collagen gels. The feeder layer cells included fetal rat lung fibroblasts, adult rat lung fibroblasts, fetal rat skin fibroblasts, bovine aortic endothelial cells, and rat mammary tumor epithelial cells. One-half of the gels remained attached to the culture dish and one-half of the gels were detached after 24 h and allowed to float free in the medium. Type II cells grown in association with any of the attached feeder layers became flattened and lost their differentiated phenotype. These cells incorporated no greater percentage of acetate into PC than did cells on plastic. Saturated PC synthesis was modestly increased. PG synthesis declined in parallel with that seen in cells cultured on plastic. Type II cells cultured on feeder layers that were detached assumed their native cuboidal shape and also exhibited many morphological characteristics of differentiated function. These cells incorporated a significantly greater percentage of acetate into PC compared to cells on either plastic or attached feeder layers. Saturated PC synthesis also increased markedly. These cells, however, incorporated no greater percentage of acetate into PG than did cells on plastic or attached feeder layers. These data suggest an important role for cell shape and cell-matrix interactions and maintenance of type II cell differentiation. The effects of cell-cell interactions, while beneficial, appear to be non-specific.
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