Role of Specific CCAAT/Enhancer-binding Protein Isoforms in Intestinal Epithelial Cells

Intestinal epithelial cells participate in the acute phase response in response to inflammation. We have shown that acute phase protein genes are induced during intestinal acute phase response, and that the CCAAT/enhancer binding protein family of transcription factors are involved. To address the role of specific C/EBP isoforms, we generated IEC-6 rat intestinal epithelial cell lines expressing different C/EBP isoforms, by retroviral infection. Overexpression of C/EBPα p30 and C/EBPδ led to increases in C/EBPβ LAP and C/EBPβ LIP endogenous protein levels, as determined by electrophoretic mobility shift assays and Western blot. Inhibition of C/EBP activity with dominant negative C/EBPs (C/EBPβ LIP, 3hF, 4hF) decreased glucocorticoid-, cAMP- and IL-1 responsiveness of the endogenous haptoglobin gene, while overexpression of each C/EBP isoform increased the responsiveness to these regulators. In contrast, dominant negative C/EBPs or C/EBP isoforms did not alter the expression of α-acid glycoprotein in response to dexamethasone and of C/EBPβ and C/EBPδ in response to various regulators as assessed by Northern blot. These data show that the three C/EBP isoforms are involved in the regulation of haptoglobin and that C/EBPβ, C/EBPδ, and α-acid glycoprotein expression are not induced by C/EBP isoforms in contrast to other cell types. C/EBPβ LAP-expressing cells showed an inhibition of cell growth characterized by a delay in p27Kip1decrease in response to serum and a decrease in cyclin D isoforms and cyclin E protein levels. Finally, C/EBP isoforms interact with the E2F4 transcription factor. Thus, specific C/EBP isoforms are involved in the differential expression of acute phase protein genes in response to hormones and cytokines. Furthermore, C/EBP isoforms may play a role in the control of cell cycle progression. Intestinal epithelial cells participate in the acute phase response in response to inflammation. We have shown that acute phase protein genes are induced during intestinal acute phase response, and that the CCAAT/enhancer binding protein family of transcription factors are involved. To address the role of specific C/EBP isoforms, we generated IEC-6 rat intestinal epithelial cell lines expressing different C/EBP isoforms, by retroviral infection. Overexpression of C/EBPα p30 and C/EBPδ led to increases in C/EBPβ LAP and C/EBPβ LIP endogenous protein levels, as determined by electrophoretic mobility shift assays and Western blot. Inhibition of C/EBP activity with dominant negative C/EBPs (C/EBPβ LIP, 3hF, 4hF) decreased glucocorticoid-, cAMP- and IL-1 responsiveness of the endogenous haptoglobin gene, while overexpression of each C/EBP isoform increased the responsiveness to these regulators. In contrast, dominant negative C/EBPs or C/EBP isoforms did not alter the expression of α-acid glycoprotein in response to dexamethasone and of C/EBPβ and C/EBPδ in response to various regulators as assessed by Northern blot. These data show that the three C/EBP isoforms are involved in the regulation of haptoglobin and that C/EBPβ, C/EBPδ, and α-acid glycoprotein expression are not induced by C/EBP isoforms in contrast to other cell types. C/EBPβ LAP-expressing cells showed an inhibition of cell growth characterized by a delay in p27Kip1decrease in response to serum and a decrease in cyclin D isoforms and cyclin E protein levels. Finally, C/EBP isoforms interact with the E2F4 transcription factor. Thus, specific C/EBP isoforms are involved in the differential expression of acute phase protein genes in response to hormones and cytokines. Furthermore, C/EBP isoforms may play a role in the control of cell cycle progression. acute phase proteins Dulbecco's modified Eagle's medium fetal bovine serum immunoprecipitation-electrophoretic mobility shift assays green fluorescent protein mitogen-activated protein Intestinal epithelial cells form a critical mucosal barrier between the host's internal milieu and the external environment and serve as an integral component of the mucosal immune system (1Chang E.B. Inflammatory Bowel Diseases. W. B. Saunders, Philadelphia, PA2000: 3-19Google Scholar). The inflammatory response in the gastrointestinal tract is mediated by the concerted actions of cellular and humoral elements, including cytokines, reactive oxygen metabolites, and bacterial products (2Mayer L. Inflammatory Bowel Diseases. W. B. Saunders, Philadelphia, PA2000: 280-297Google Scholar). An increasing body of evidence has demonstrated that intestinal epithelial cells can actively participate in the generation of an immune response (3Sanderson A.R. Walker W.A. Inflammatory Bowel Diseases. W. B. Saunders, Philadelphia, PA2000: 65-73Google Scholar). In fact, intestinal epithelial cells participate in intestinal homeostasis and mucosal immunity by secreting and responding to cytokines (4Podolsky D.K. Fiocchi C. Inflammatory Bowel Diseases. W. B. Saunders, Philadelphia, PA2000: 191-207Google Scholar).The intestinal inflammatory response leads to the establishment of an acute phase response characterized by the local production of acute phase proteins (APPs)1 in response to cytokines and hormones (5Mackiewicz A. Int. J. Cytol. 1997; 170: 225-300Crossref PubMed Google Scholar). For example, we have shown that the APP gene haptoglobin is induced in various rat models of intestinal inflammation (6Boudreau F. Bardati T. Nadeau A. Blouin R. Asselin C. Gastroenterology. 1997; 112 (Abstr. 940)Google Scholar) and in the rat intestinal epithelial cell line IEC-6 in response to cAMP and glucocorticoids (7Pelletier N. Boudreau F. S.-J. Yu Zannoni S. Boulanger V. Asselin C. FEBS Lett. 1998; 439: 275-280Crossref PubMed Scopus (27) Google Scholar, 8Yu S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar). The CCAAT/enhancer-binding protein family of transcription factors is one class of transactivators involved in the regulation of APP expression in various tissues, including the intestine (9Poli V. J. Biol. Chem. 1998; 273: 29279-29282Abstract PubMed Scopus Google Scholar). These genes to a class of transcription factors with and that the various C/EBP isoforms to form or M. Int. J. 1998; PubMed Scopus Google Scholar). C/EBP isoforms show differential expression during and and during the acute phase response in tissues, including the intestine M. Int. J. 1998; PubMed Scopus Google Scholar). C/EBPα a role in J. Biol. Chem. 1998; 273: PubMed Scopus Google Scholar) and is a of homeostasis in J. J. Biol. Chem. 1998; 273: PubMed Scopus Google Scholar). C/EBPα cell in cell lines Res. PubMed Scopus Google Scholar) and may control the acute phase response in Biol. 1998; PubMed Scopus Google Scholar). In to a role in the of C/EBPβ and C/EBPδ are of the acute phase response in (9Poli V. J. Biol. Chem. 1998; 273: 29279-29282Abstract PubMed Scopus Google Scholar) and intestinal epithelial cells S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar, F. S. Asselin C. Res. PubMed Scopus Google Scholar, A. S.-J. Yu Asselin C. Biochem. Biophys. Res. Commun. PubMed Scopus Google Scholar). Furthermore, C/EBPβ is involved in the control of cell in J. Biol. Chem. 1998; 273: PubMed Scopus Google Scholar). have shown that C/EBP isoforms control the of C/EBPβ Biol. PubMed Scopus Google Scholar) and C/EBPδ T. T. S. T. M. Biochem. Biophys. Res. Commun. 1998; PubMed Scopus (27) Google Scholar) in cell by and to a C/EBPδ, are induced in intestine inflammation induced by the (6Boudreau F. Bardati T. Nadeau A. Blouin R. Asselin C. Gastroenterology. 1997; 112 (Abstr. 940)Google Scholar, An J. J. Biol. Chem. PubMed Google Scholar) and the protein (6Boudreau F. Bardati T. Nadeau A. Blouin R. Asselin C. Gastroenterology. 1997; 112 (Abstr. 940)Google Scholar, W. J. PubMed Scopus (15) Google Scholar). we have shown that C/EBP isoforms are involved in the regulation of APP genes in intestinal epithelial cells S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar, F. S. Asselin C. Res. PubMed Scopus Google Scholar, A. S.-J. Yu Asselin C. Biochem. Biophys. Res. Commun. PubMed Scopus Google Scholar). while the role of specific C/EBP isoforms, C/EBPβ, and C/EBPδ as as isoforms C/EBPβ J. J. Biol. Chem. 1998; 273: PubMed Scopus Google Scholar) is in other tissues, role in the control of intestinal APP gene expression or intestinal epithelial cell is not The of the to the expression of specific C/EBP isoforms or to C/EBP activity in the rat intestinal epithelial cell line IEC-6 and to the of these cell lines to the regulation of the acute phase response as as of cell data in show that C/EBP isoforms are involved in the regulation of the acute phase protein gene inhibition of C/EBP activity by the dominant negative C/EBPβ LIP Scopus Google Scholar) or by dominant negative binding 4hF) M. C. J. PubMed Scopus Google Scholar) leads to a decrease in haptoglobin expression in response to and the of C/EBP isoforms in the regulation of haptoglobin in intestinal epithelial overexpression of C/EBPα C/EBPβ and C/EBPδ leads to increased of the of haptoglobin in response to and IL-1 is increased C/EBP isoforms are that the C/EBPβ and C/EBPδ isoforms are the of haptoglobin expression (7Pelletier N. Boudreau F. S.-J. Yu Zannoni S. Boulanger V. Asselin C. FEBS Lett. 1998; 439: 275-280Crossref PubMed Scopus (27) Google Scholar, 8Yu S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar). show that C/EBPα an role in the regulation of haptoglobin in intestinal epithelial has demonstrated by the response to inflammation in C/EBPα that C/EBPα expression haptoglobin expression in as to Biol. 1998; PubMed Scopus Google Scholar). is that C/EBPα p30 is isoforms of C/EBPα the of different S. A. PubMed Scopus Google Scholar, V. S. A. PubMed Scopus Google Scholar). The C/EBPα as to the C/EBPα has a decreased to the of of three to determined the of C/EBPα p30 to haptoglobin expression to the endogenous of C/EBPβ in IEC-6 cells contrast, C/EBP isoforms are not involved in the regulation of α-acid glycoprotein by dexamethasone in intestinal epithelial overexpression of dominant negative the or the binding not α-acid glycoprotein by overexpression of specific C/EBP isoforms not α-acid glycoprotein levels. that the of α-acid glycoprotein expression is the in contrast to α-acid glycoprotein regulation in rat or in other glucocorticoids a of a C/EBP in the α-acid glycoprotein T. N. Biophys. PubMed Scopus Google Scholar). In rat and in other a between the and C/EBPs is that is not α-acid glycoprotein regulation by glucocorticoids in intestinal epithelial in the IEC-6 cell have shown that C/EBP isoforms may control the of C/EBPβ Biol. PubMed Scopus Google Scholar) and C/EBPδ T. T. S. T. M. Biochem. Biophys. Res. Commun. 1998; PubMed Scopus (27) Google Scholar) by in other cell types. Furthermore, the C/EBPα is by C/EBPα in C. Res. PubMed Scopus Google Scholar) and cells N. S. M. Biol. PubMed Google Scholar). dominant negative in cells the expression of C/EBPα J. Biol. Chem. PubMed Scopus Google Scholar). In contrast to these overexpression of dominant negative of C/EBPs or of specific C/EBP isoforms did not C/EBP isoform levels. Furthermore, C/EBPα protein not in C/EBP cell that C/EBP isoforms are not to in IEC-6 intestinal epithelial the in C/EBPβ LAP and C/EBPβ LIP endogenous protein C/EBPα p30 or C/EBPδ overexpression not is of the involved in of C/EBP isoforms in the may the that may in one isoform may alter the of by increasing the of increasing the of the C/EBP isoform the other C/EBP isoforms may with other proteins to interact with C/EBPs with For example, C/EBPα with the transcription J. J. Biol. Chem. PubMed Scopus Google Scholar). in C/EBPα protein may the of C/EBP as to increasing C/EBP binding have that C/EBPα overexpression leads to growth in IEC-6 cells not as in other cell Res. PubMed Scopus Google Scholar). cell growth the regulation of the M. M. PubMed Scopus Google Scholar) or the protein M. Biol. 1997; PubMed Google Scholar) in different cell C/EBPα has shown to cell growth by of transcription Biol. PubMed Scopus Google Scholar) and may M. Biol. 1999; PubMed Google Scholar). The involved in growth in IEC-6 cells not a regulation of not C/EBP isoforms may to control intestinal epithelial cell For example, overexpression of the C/EBP isoform the growth of cell M. Int. J. 1998; PubMed Scopus Google including IEC-6 cells not In we have shown that C/EBPβ LAP overexpression IEC-6 cell in contrast to C/EBPα C/EBPβ LIP, and C/EBPβ LAP-expressing cells are characterized by a of and a not in response to serum and by decreased of cyclin and cyclin of the and are not C/EBPβ has shown to cell M. M. J. PubMed Scopus Google Scholar). In contrast, C/EBPβ is induced by in M. V. M. T. 1999; PubMed Scopus Google Scholar). data that C/EBPβ LAP overexpression leads to a delay in of intestinal epithelial involved in the growth delay to show that C/EBP isoforms may interact with the E2F4 transcription to the of C/EBP isoforms to C/EBP isoforms p30 and LIP are by the E2F4 in IEC-6 cells these isoforms, as determined by the E2F4 C/EBPα and C/EBPβ isoforms intestinal epithelial of p30 and LAP proteins cells leads to the of the E2F4 transcription as determined by a with a These data that the involved in the with E2F4 the C/EBP and that the of C/EBPα and C/EBPβ are C/EBPβ LIP is of of the of C/EBPβ and C/EBPα p30 of three including a M. Biol. 1999; PubMed Google Scholar). C/EBP isoforms to E2F4 by the C/EBPα Res. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google Scholar) and C/EBPβ LAP growth may that the of the of C/EBPα and C/EBPβ LAP in the of to expression of as cyclin D and cyclin and decreased cell In the of these may in the of these to the we have shown the of different C/EBP isoform as as acute phase protein gene expression in intestinal epithelial C/EBP isoforms are involved in the differential expression of APP genes in response to hormones and cytokines. Furthermore, C/EBP isoforms, including C/EBPβ, may play an role in the control of intestinal epithelial cell Intestinal epithelial cells form a critical mucosal barrier between the host's internal milieu and the external environment and serve as an integral component of the mucosal immune system (1Chang E.B. Inflammatory Bowel Diseases. W. B. Saunders, Philadelphia, PA2000: 3-19Google Scholar). The inflammatory response in the gastrointestinal tract is mediated by the concerted actions of cellular and humoral elements, including cytokines, reactive oxygen metabolites, and bacterial products (2Mayer L. Inflammatory Bowel Diseases. W. B. Saunders, Philadelphia, PA2000: 280-297Google Scholar). An increasing body of evidence has demonstrated that intestinal epithelial cells can actively participate in the generation of an immune response (3Sanderson A.R. Walker W.A. Inflammatory Bowel Diseases. W. B. Saunders, Philadelphia, PA2000: 65-73Google Scholar). In fact, intestinal epithelial cells participate in intestinal homeostasis and mucosal immunity by secreting and responding to cytokines (4Podolsky D.K. Fiocchi C. Inflammatory Bowel Diseases. W. B. Saunders, Philadelphia, PA2000: 191-207Google Scholar). The intestinal inflammatory response leads to the establishment of an acute phase response characterized by the local production of acute phase proteins (APPs)1 in response to cytokines and hormones (5Mackiewicz A. Int. J. Cytol. 1997; 170: 225-300Crossref PubMed Google Scholar). For example, we have shown that the APP gene haptoglobin is induced in various rat models of intestinal inflammation (6Boudreau F. Bardati T. Nadeau A. Blouin R. Asselin C. Gastroenterology. 1997; 112 (Abstr. 940)Google Scholar) and in the rat intestinal epithelial cell line IEC-6 in response to cAMP and glucocorticoids (7Pelletier N. Boudreau F. S.-J. Yu Zannoni S. Boulanger V. Asselin C. FEBS Lett. 1998; 439: 275-280Crossref PubMed Scopus (27) Google Scholar, 8Yu S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar). The CCAAT/enhancer-binding protein family of transcription factors is one class of transactivators involved in the regulation of APP expression in various tissues, including the intestine (9Poli V. J. Biol. Chem. 1998; 273: 29279-29282Abstract PubMed Scopus Google Scholar). These genes to a class of transcription factors with and that the various C/EBP isoforms to form or M. Int. J. 1998; PubMed Scopus Google Scholar). C/EBP isoforms show differential expression during and and during the acute phase response in tissues, including the intestine M. Int. J. 1998; PubMed Scopus Google Scholar). C/EBPα a role in J. Biol. Chem. 1998; 273: PubMed Scopus Google Scholar) and is a of homeostasis in J. J. Biol. Chem. 1998; 273: PubMed Scopus Google Scholar). C/EBPα cell in cell lines Res. PubMed Scopus Google Scholar) and may control the acute phase response in Biol. 1998; PubMed Scopus Google Scholar). In to a role in the of C/EBPβ and C/EBPδ are of the acute phase response in (9Poli V. J. Biol. Chem. 1998; 273: 29279-29282Abstract PubMed Scopus Google Scholar) and intestinal epithelial cells S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar, F. S. Asselin C. Res. PubMed Scopus Google Scholar, A. S.-J. Yu Asselin C. Biochem. Biophys. Res. Commun. PubMed Scopus Google Scholar). Furthermore, C/EBPβ is involved in the control of cell in J. Biol. Chem. 1998; 273: PubMed Scopus Google Scholar). have shown that C/EBP isoforms control the of C/EBPβ Biol. PubMed Scopus Google Scholar) and C/EBPδ T. T. S. T. M. Biochem. Biophys. Res. Commun. 1998; PubMed Scopus (27) Google Scholar) in cell by C/EBPβ, and to a C/EBPδ, are induced in intestine inflammation induced by the (6Boudreau F. Bardati T. Nadeau A. Blouin R. Asselin C. Gastroenterology. 1997; 112 (Abstr. 940)Google Scholar, An J. J. Biol. Chem. PubMed Google Scholar) and the protein (6Boudreau F. Bardati T. Nadeau A. Blouin R. Asselin C. Gastroenterology. 1997; 112 (Abstr. 940)Google Scholar, W. J. PubMed Scopus (15) Google Scholar). we have shown that C/EBP isoforms are involved in the regulation of APP genes in intestinal epithelial cells S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar, F. S. Asselin C. Res. PubMed Scopus Google Scholar, A. S.-J. Yu Asselin C. Biochem. Biophys. Res. Commun. PubMed Scopus Google Scholar). while the role of specific C/EBP isoforms, C/EBPβ, and C/EBPδ as as isoforms C/EBPβ J. J. Biol. Chem. 1998; 273: PubMed Scopus Google Scholar) is in other tissues, role in the control of intestinal APP gene expression or intestinal epithelial cell is not The of the to the expression of specific C/EBP isoforms or to C/EBP activity in the rat intestinal epithelial cell line IEC-6 and to the of these cell lines to the regulation of the acute phase response as as of cell data in show that C/EBP isoforms are involved in the regulation of the acute phase protein gene inhibition of C/EBP activity by the dominant negative C/EBPβ LIP Scopus Google Scholar) or by dominant negative binding 4hF) M. C. J. PubMed Scopus Google Scholar) leads to a decrease in haptoglobin expression in response to and the of C/EBP isoforms in the regulation of haptoglobin in intestinal epithelial overexpression of C/EBPα C/EBPβ and C/EBPδ leads to increased of the of haptoglobin in response to and IL-1 is increased C/EBP isoforms are that the C/EBPβ and C/EBPδ isoforms are the of haptoglobin expression (7Pelletier N. Boudreau F. S.-J. Yu Zannoni S. Boulanger V. Asselin C. FEBS Lett. 1998; 439: 275-280Crossref PubMed Scopus (27) Google Scholar, 8Yu S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar). show that C/EBPα an role in the regulation of haptoglobin in intestinal epithelial has demonstrated by the response to inflammation in C/EBPα that C/EBPα expression haptoglobin expression in as to Biol. 1998; PubMed Scopus Google Scholar). is that C/EBPα p30 is isoforms of C/EBPα the of different S. A. PubMed Scopus Google Scholar, V. S. A. PubMed Scopus Google Scholar). The C/EBPα as to the C/EBPα has a decreased to the of of three to determined the of C/EBPα p30 to haptoglobin expression to the endogenous of C/EBPβ in IEC-6 cells contrast, C/EBP isoforms are not involved in the regulation of α-acid glycoprotein by dexamethasone in intestinal epithelial overexpression of dominant negative the or the binding not α-acid glycoprotein by overexpression of specific C/EBP isoforms not α-acid glycoprotein levels. that the of α-acid glycoprotein expression is the in contrast to α-acid glycoprotein regulation in rat or in other glucocorticoids a of a C/EBP in the α-acid glycoprotein T. N. Biophys. PubMed Scopus Google Scholar). In rat and in other a between the and C/EBPs is that is not α-acid glycoprotein regulation by glucocorticoids in intestinal epithelial in the IEC-6 cell have shown that C/EBP isoforms may control the of C/EBPβ Biol. PubMed Scopus Google Scholar) and C/EBPδ T. T. S. T. M. Biochem. Biophys. Res. Commun. 1998; PubMed Scopus (27) Google Scholar) by in other cell types. Furthermore, the C/EBPα is by C/EBPα in C. Res. PubMed Scopus Google Scholar) and cells N. S. M. Biol. PubMed Google Scholar). dominant negative in cells the expression of C/EBPα J. Biol. Chem. PubMed Scopus Google Scholar). In contrast to these overexpression of dominant negative of C/EBPs or of specific C/EBP isoforms did not C/EBP isoform levels. Furthermore, C/EBPα protein not in C/EBP cell that C/EBP isoforms are not to in IEC-6 intestinal epithelial the in C/EBPβ LAP and C/EBPβ LIP endogenous protein C/EBPα p30 or C/EBPδ overexpression not is of the involved in of C/EBP isoforms in the may the that may in one isoform may alter the of by increasing the of increasing the of the C/EBP isoform the other C/EBP isoforms may with other proteins to interact with C/EBPs with For example, C/EBPα with the transcription J. J. Biol. Chem. PubMed Scopus Google Scholar). in C/EBPα protein may the of C/EBP as to increasing C/EBP binding have that C/EBPα overexpression leads to growth in IEC-6 cells not as in other cell Res. PubMed Scopus Google Scholar). cell growth the regulation of the M. M. PubMed Scopus Google Scholar) or the protein M. Biol. 1997; PubMed Google Scholar) in different cell C/EBPα has shown to cell growth by of transcription Biol. PubMed Scopus Google Scholar) and may M. Biol. 1999; PubMed Google Scholar). The involved in growth in IEC-6 cells not a regulation of not C/EBP isoforms may to control intestinal epithelial cell For example, overexpression of the C/EBP isoform the growth of cell M. Int. J. 1998; PubMed Scopus Google including IEC-6 cells not In we have shown that C/EBPβ LAP overexpression IEC-6 cell in contrast to C/EBPα C/EBPβ LIP, and C/EBPβ LAP-expressing cells are characterized by a of and a not in response to serum and by decreased of cyclin and cyclin of the and are not C/EBPβ has shown to cell M. M. J. PubMed Scopus Google Scholar). In contrast, C/EBPβ is induced by in M. V. M. T. 1999; PubMed Scopus Google Scholar). data that C/EBPβ LAP overexpression leads to a delay in of intestinal epithelial involved in the growth delay to show that C/EBP isoforms may interact with the E2F4 transcription to the of C/EBP isoforms to C/EBP isoforms p30 and LIP are by the E2F4 in IEC-6 cells these isoforms, as determined by the E2F4 C/EBPα and C/EBPβ isoforms intestinal epithelial of p30 and LAP proteins cells leads to the of the E2F4 transcription as determined by a with a These data that the involved in the with E2F4 the C/EBP and that the of C/EBPα and C/EBPβ are C/EBPβ LIP is of of the of C/EBPβ and C/EBPα p30 of three including a M. Biol. 1999; PubMed Google Scholar). C/EBP isoforms to E2F4 by the C/EBPα Res. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google Scholar) and C/EBPβ LAP growth may that the of the of C/EBPα and C/EBPβ LAP in the of to expression of as cyclin D and cyclin and decreased cell In the of these may in the of these to the we have shown the of different C/EBP isoform as as acute phase protein gene expression in intestinal epithelial C/EBP isoforms are involved in the differential expression of APP genes in response to hormones and cytokines. Furthermore, C/EBP isoforms, including C/EBPβ, may play an role in the control of intestinal epithelial cell The data in show that C/EBP isoforms are involved in the regulation of the acute phase protein gene inhibition of C/EBP activity by the dominant negative C/EBPβ LIP Scopus Google Scholar) or by dominant negative binding 4hF) M. C. J. PubMed Scopus Google Scholar) leads to a decrease in haptoglobin expression in response to and the of C/EBP isoforms in the regulation of haptoglobin in intestinal epithelial overexpression of C/EBPα C/EBPβ and C/EBPδ leads to increased of the of haptoglobin in response to and IL-1 is increased C/EBP isoforms are that the C/EBPβ and C/EBPδ isoforms are the of haptoglobin expression (7Pelletier N. Boudreau F. S.-J. Yu Zannoni S. Boulanger V. Asselin C. FEBS Lett. 1998; 439: 275-280Crossref PubMed Scopus (27) Google Scholar, 8Yu S.-J. Boudreau F. Désilets A. Houde M. Rivard N. Asselin C. Biochem. Biophys. Res. Commun. 1999; 259: 544-549Crossref PubMed Scopus (15) Google Scholar). show that C/EBPα an role in the regulation of haptoglobin in intestinal epithelial has demonstrated by the response to inflammation in C/EBPα that C/EBPα expression haptoglobin expression in as to Biol. 1998; PubMed Scopus Google Scholar). is that C/EBPα p30 is isoforms of C/EBPα the of different S. A. PubMed Scopus Google Scholar, V. S. A. PubMed Scopus Google Scholar). The C/EBPα as to the C/EBPα has a decreased to the of of three to determined the of C/EBPα p30 to haptoglobin expression to the endogenous of C/EBPβ in IEC-6 cells In contrast, C/EBP isoforms are not involved in the regulation of α-acid glycoprotein by dexamethasone in intestinal epithelial overexpression of dominant negative the or the binding not α-acid glycoprotein by overexpression of specific C/EBP isoforms not α-acid glycoprotein levels. that the of α-acid glycoprotein expression is the in contrast to α-acid glycoprotein regulation in rat or in other glucocorticoids a of a C/EBP in the α-acid glycoprotein T. N. Biophys. PubMed Scopus Google Scholar). In rat and in other a between the and C/EBPs is that is not α-acid glycoprotein regulation by glucocorticoids in intestinal epithelial in the IEC-6 cell have shown that C/EBP isoforms may control the of C/EBPβ Biol. PubMed Scopus Google Scholar) and C/EBPδ T. T. S. T. M. Biochem. Biophys. Res. Commun. 1998; PubMed Scopus (27) Google Scholar) by in other cell types. Furthermore, the C/EBPα is by C/EBPα in C. Res. PubMed Scopus Google Scholar) and cells N. S. M. Biol. PubMed Google Scholar). dominant negative in cells the expression of C/EBPα J. Biol. Chem. PubMed Scopus Google Scholar). In contrast to these overexpression of dominant negative of C/EBPs or of specific C/EBP isoforms did not C/EBP isoform levels. Furthermore, C/EBPα protein not in C/EBP cell that C/EBP isoforms are not to in IEC-6 intestinal epithelial Thus, the in C/EBPβ LAP and C/EBPβ LIP endogenous protein C/EBPα p30 or C/EBPδ overexpression not is of the involved in of C/EBP isoforms in the may the that may in one isoform may alter the of by increasing the of increasing the of the C/EBP isoform the other C/EBP isoforms may with other proteins to interact with C/EBPs with For example, C/EBPα with the transcription J. J. Biol. Chem. PubMed Scopus Google Scholar). in C/EBPα protein may the of C/EBP as to increasing C/EBP binding We have that C/EBPα overexpression leads to growth in IEC-6 cells not as in other cell Res. PubMed Scopus Google Scholar). cell growth the regulation of the M. M. PubMed Scopus Google Scholar) or the protein M. Biol. 1997; PubMed Google Scholar) in different cell C/EBPα has shown to cell growth by of transcription Biol. PubMed Scopus Google Scholar) and may M. Biol. 1999; PubMed Google Scholar). The involved in growth in IEC-6 cells not a regulation of not C/EBP isoforms may to control intestinal epithelial cell For example, overexpression of the C/EBP isoform the growth of cell M. Int. J. 1998; PubMed Scopus Google including IEC-6 cells not In we have shown that C/EBPβ LAP overexpression IEC-6 cell in contrast to C/EBPα C/EBPβ LIP, and C/EBPβ LAP-expressing cells are characterized by a of and a not in response to serum and by decreased of cyclin and cyclin of the and are not C/EBPβ has shown to cell M. M. J. PubMed Scopus Google Scholar). In contrast, C/EBPβ is induced by in M. V. M. T. 1999; PubMed Scopus Google Scholar). data that C/EBPβ LAP overexpression leads to a delay in of intestinal epithelial The involved in the growth delay to show that C/EBP isoforms may interact with the E2F4 transcription to the of C/EBP isoforms to C/EBP isoforms p30 and LIP are by the E2F4 in IEC-6 cells these isoforms, as determined by the E2F4 C/EBPα and C/EBPβ isoforms intestinal epithelial of p30 and LAP proteins cells leads to the of the E2F4 transcription as determined by a with a These data that the involved in the with E2F4 the C/EBP and that the of C/EBPα and C/EBPβ are C/EBPβ LIP is of of the of C/EBPβ and C/EBPα p30 of three including a M. Biol. 1999; PubMed Google Scholar). C/EBP isoforms to E2F4 by the C/EBPα Res. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google Scholar) and C/EBPβ LAP growth may that the of the of C/EBPα and C/EBPβ LAP in the of to expression of as cyclin D and cyclin and decreased cell In the of these may in the of these to the Thus, we have shown the of different C/EBP isoform as as acute phase protein gene expression in intestinal epithelial C/EBP isoforms are involved in the differential expression of APP genes in response to hormones and cytokines. Furthermore, C/EBP isoforms, including C/EBPβ, may play an role in the control of intestinal epithelial cell We S. L. C. and N. A. the and the cell and

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.