Role of p27(Kip1) in human intestinal cell differentiation.
OBJECTIVE
Growth arrest and differentiation are generally considered to be temporally and functionally linked phenomena in the intestinal epithelium.


METHODS
To delineate the mechanism(s) responsible for the loss of proliferative potential as committed intestinal cells start to differentiate, we have analyzed the regulation of G(1)-phase regulatory proteins in relation to differentiation in the intact epithelium as well as in well-established intestinal cell models that allow the recapitulation of the crypt-villus axis in vitro.


RESULTS
With intestinal cell differentiation, we have observed an induction of the cell cycle inhibitors p21(Cip), p27(Kip1), and p57(Kip2) expression with an increased association of p27(Kip1) and p57(Kip2) with cyclin-dependent kinase 2 (Cdk2). At the same time, there was an accumulation of the hypophosphorylated form of the pRb proteins and a strong decline in Cdk2 activity. Stable expression of a p27(Kip1) antisense complementary DNA in Caco-2/15 cells did not prevent growth arrest induced by confluence, but repressed villin, sucrase-isomaltase, and alkaline phosphatase expression.


CONCLUSIONS
Our results indicate that the growth arrest that precedes differentiation involves the activation of Rb proteins and the inhibition of Cdk2. Furthermore, intestinal cell differentiation apparently requires a function of p27(Kip1) other than that which leads to inhibition of Cdks.
Deschênes
C
C
Medical Research Council Group in Functional Development and Physiopathology of the Digestive Tract, Département d'Anatomie et Biologie Cellulaire, Faculté de Médecine, Université de Sherbrooke, Quebec, Canada.
Vézina
A
A
Beaulieu
J F
JF
Rivard
N
N
D016375:Antisense Elements (Genetics); D042846:CDC2-CDC28 Kinases; D018938:Caco-2 Cells; D018797:Cell Cycle Proteins; D002454:Cell Differentiation / Q000502:physiology; D056741:Cyclin D; D019938:Cyclin D1 / Q000378:metabolism; D019927:Cyclin E / Q000235:genetics; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D050761:Cyclin-Dependent Kinase Inhibitor p57; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000201:enzymology; D005333:Fetus / Q000166:cytology; D016193:G1 Phase / Q000502:physiology; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology* / Q000201:enzymology*; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D016160:Retinoblastoma Protein / Q000378:metabolism; D013394:Sucrase-Isomaltase Complex / Q000235:genetics; D025521:Tumor Suppressor Proteins
D016375:Antisense Elements (Genetics); C493956:CDKN1A protein, human; C493964:CDKN1C protein, human; D018797:Cell Cycle Proteins; D056741:Cyclin D; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050761:Cyclin-Dependent Kinase Inhibitor p57; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016160:Retinoblastoma Protein; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; C495900:CDK4 protein, human; C495911:CDK6 protein, human; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases; D013394:Sucrase-Isomaltase Complex