Extracellular matrix modulates enterocyte growth via downregulation of c-jun but is independent of p21 and p27 expression.
Regulation of the intestinal crypt-villus axis is multifactorial and involves growth factors and extracellular matrix composition. Laminin, a component of the enterocyte basement membrane, induces enterocyte differentiation and inhibits proliferation. To investigate the mechanism of this observation, we examined the expression of cell cycle modulators in enterocytes cultured on laminin. IEC-6 enterocytes were cultured on collagen I or laminin for 24 hours in media with serum followed by 48 hours of culture in serum-free media. Cells were then stimulated with epidermal growth factor, and RNA and protein were extracted before and up to 18 hours after stimulation. c-jun mRNA expression and p21 and p27 protein expression were analyzed. Expression of c-jun was inhibited in cells grown on laminin as compared to collagen I. Expression of p21 and p27 was no different between cells grown on laminin or collagen I. The mechanism of enterocyte growth inhibition mediated by laminin involves downregulation of c-jun expression. In contrast, p21 and p27 levels were unaffected by extracellular matrix indicating that the changes in expression of these cyclin-dependent kinase inhibitors do not contribute to the effect of laminin on enterocyte proliferation.
Wolpert
S I
SI
Department of Surgery, University of Maryland, and the Baltimore VA Medical Center, Baltimore, MD, USA.
Lally
K M
KM
Li
J
J
Wang
J Y
JY
Bass
B L
BL
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003094:Collagen / Q000494:pharmacology*; D003470:Culture Media; D016895:Culture Media, Serum-Free; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors*; D015536:Down-Regulation; D020895:Enterocytes / Q000166:cytology / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000494:pharmacology*; D005786:Gene Expression Regulation; D016147:Genes, Tumor Suppressor / Q000187:drug effects / Q000235:genetics; D007797:Laminin / Q000494:pharmacology*; D008869:Microtubule-Associated Proteins / Q000032:analysis / Q000187:drug effects* / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000032:analysis / Q000187:drug effects* / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras) / Q000032:analysis / Q000187:drug effects* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D025521:Tumor Suppressor Proteins
C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D003470:Culture Media; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D007797:Laminin; D008869:Microtubule-Associated Proteins; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004815:Epidermal Growth Factor; D003094:Collagen; D018844:Cyclin-Dependent Kinases; D016283:Proto-Oncogene Proteins p21(ras)