scholarly journals Molecular cloning of gene sequences regulated during squamous differentiation of tracheal epithelial cells and controlled by retinoic acid.

1987 ◽  
Vol 7 (11) ◽  
pp. 4017-4023 ◽  
Author(s):  
H L Smits ◽  
E E Floyd ◽  
A M Jetten

A cDNA library was constructed from polyadenylated RNA present in squamous differentiated rabbit tracheal epithelial cells. Screening of the cDNA library was aimed at identifying RNAs that were abundant in squamous cells and expressed at low levels in undifferentiated cells. Two different recombinants were obtained containing inserts, 0.86 and 0.77 kilobases (kb) in size, that hybridized to mRNAs 1.0 and 1.25 kb in length. These RNAs were present at approximately 50-fold higher levels in squamous cells than in proliferative or confluent retinoic acid-treated cells. The increase in the levels of the 1.0- and 1.25-kb RNAs correlated closely with the onset of squamous differentiation and was not related to induction of terminal cell division. Treatment of rabbit tracheal epithelial cells with transforming growth factor beta, which induces squamous differentiation in these cells, also resulted in elevated levels of the 1.0- and 1.25-kb RNAs. The increased levels of these RNAs in squamous cells appeared to a large extent to be regulated at a posttranscriptional level. Retinoic acid not only inhibited the increase in the levels of the 1.0- and 1.25-kb RNAs but also reversed the expression of these RNAs in squamous cells. These results suggest that retinoic acid affects, directly or indirectly, molecular events that induce alterations in the posttranscriptional processing of the transcripts corresponding to the 1.0- and 1.25-kb RNAs.

1987 ◽  
Vol 7 (11) ◽  
pp. 4017-4023
Author(s):  
H L Smits ◽  
E E Floyd ◽  
A M Jetten

A cDNA library was constructed from polyadenylated RNA present in squamous differentiated rabbit tracheal epithelial cells. Screening of the cDNA library was aimed at identifying RNAs that were abundant in squamous cells and expressed at low levels in undifferentiated cells. Two different recombinants were obtained containing inserts, 0.86 and 0.77 kilobases (kb) in size, that hybridized to mRNAs 1.0 and 1.25 kb in length. These RNAs were present at approximately 50-fold higher levels in squamous cells than in proliferative or confluent retinoic acid-treated cells. The increase in the levels of the 1.0- and 1.25-kb RNAs correlated closely with the onset of squamous differentiation and was not related to induction of terminal cell division. Treatment of rabbit tracheal epithelial cells with transforming growth factor beta, which induces squamous differentiation in these cells, also resulted in elevated levels of the 1.0- and 1.25-kb RNAs. The increased levels of these RNAs in squamous cells appeared to a large extent to be regulated at a posttranscriptional level. Retinoic acid not only inhibited the increase in the levels of the 1.0- and 1.25-kb RNAs but also reversed the expression of these RNAs in squamous cells. These results suggest that retinoic acid affects, directly or indirectly, molecular events that induce alterations in the posttranscriptional processing of the transcripts corresponding to the 1.0- and 1.25-kb RNAs.


1989 ◽  
Vol 9 (11) ◽  
pp. 4846-4851
Author(s):  
E E Floyd ◽  
A M Jetten

Squamous differentiation of rabbit tracheal epithelial cells is accompanied by an approximately 50-fold increase in the activity of type I (epidermal) transglutaminase, while the levels of type II (tissue) transglutaminase remain almost undetectable. To identify a cDNA encoding type I transglutaminase, we screened a library of cDNA clones prepared from poly(A)+ RNA isolated from squamous-differentiated rabbit tracheal epithelial cells. Four overlapping clones (represented by clone pTG-7) which span a range of 2.8 kilobases were identified; partial sequencing of pTG-7 indicated that it encodes a transglutaminaselike protein. pTG-7 hybridized to a 3.6-kilobase mRNA which is distinct from that for type II transglutaminase. pTG-7 mRNA levels were low in proliferative cells, increased dramatically in squamous-differentiated cells, and could be further enhanced by growth of the cells in high concentrations (2 mM) of calcium ions. Retinoic acid, which blocks the expression of the squamous phenotype, prevented this increase in pTG-7 mRNA levels. These changes in levels of pTG-7 mRNA parallel the changes in type I transglutaminase activity observed under similar culture conditions. These data indicate that pTG-7 encodes the mRNA for transglutaminase type I and that expression of this mRNA is negatively regulated by retinoic acid.


1989 ◽  
Vol 9 (11) ◽  
pp. 4846-4851 ◽  
Author(s):  
E E Floyd ◽  
A M Jetten

Squamous differentiation of rabbit tracheal epithelial cells is accompanied by an approximately 50-fold increase in the activity of type I (epidermal) transglutaminase, while the levels of type II (tissue) transglutaminase remain almost undetectable. To identify a cDNA encoding type I transglutaminase, we screened a library of cDNA clones prepared from poly(A)+ RNA isolated from squamous-differentiated rabbit tracheal epithelial cells. Four overlapping clones (represented by clone pTG-7) which span a range of 2.8 kilobases were identified; partial sequencing of pTG-7 indicated that it encodes a transglutaminaselike protein. pTG-7 hybridized to a 3.6-kilobase mRNA which is distinct from that for type II transglutaminase. pTG-7 mRNA levels were low in proliferative cells, increased dramatically in squamous-differentiated cells, and could be further enhanced by growth of the cells in high concentrations (2 mM) of calcium ions. Retinoic acid, which blocks the expression of the squamous phenotype, prevented this increase in pTG-7 mRNA levels. These changes in levels of pTG-7 mRNA parallel the changes in type I transglutaminase activity observed under similar culture conditions. These data indicate that pTG-7 encodes the mRNA for transglutaminase type I and that expression of this mRNA is negatively regulated by retinoic acid.


1994 ◽  
Vol 267 (6) ◽  
pp. L693-L703 ◽  
Author(s):  
S. Idell ◽  
A. Kumar ◽  
C. Zwieb ◽  
D. Holiday ◽  
K. B. Koenig ◽  
...  

The epithelial lining of the airways is subject to injury through several processes, including infections, bronchiolitis, and fume exposures. Because airway fibrin deposition influences the course of local injury, we examined how two inflammatory cytokines influenced fibrin formation and clearance in human tracheal epithelial cells (TEC). TEC were treated with transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha). TNF-alpha increased release of tissue factor (TF)-related procoagulant activity that, through generation of factor Xa, promotes assembly of the prothrombinase complex at the cell surface. Fibrinolytic activity was plasminogen dependent and due to both urokinase (uPA) and tissue plasminogen activator (tPA). The cells expressed plasminogen activator inhibitor 1 (PAI-1), but relatively little PAI-2. Depression of fibrinolysis by TGF-beta correlated with increased PAI-1. Conversely, TNF-alpha increased plasminogen activator (PA) activity due to increased uPA. Fibrinolytic activity was inhibited by actinomycin D and cyclohexamide, but changes in mRNAs for uPA, tPA, PAI-1, and TF by either cytokine were not appreciable. PAI-2 mRNA was not found. The data indicate that TGF-beta decreases the fibrinolytic capacity of TEC, suggesting that this cytokine promotes fibrin retention. TNF-alpha increases expression of both procoagulant and fibrinolytic activities; this differential regulation could favor both pericellular fibrin formation and dissolution.


1987 ◽  
Vol 54 (1) ◽  
pp. 38-51 ◽  
Author(s):  
Elizabeth M. McDowell ◽  
Theresa Ben ◽  
Bill Coleman ◽  
Seung Chang ◽  
Carnell Newkirk ◽  
...  

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