Abstract
The Caudal-related homeodomain transcription factor Cdx2 plays a key role in intestinal cell fate determination. Reduction of Cdx2 expression is a feature of many human colon carcinomas and inactivation of one cdx2 allele facilitates the development of invasive adenocarcinoma in the murine colon. Here, we investigated the post-translational regulation of Cdx2. We showed that various forms of Cdx2 coexist in the intestine and colon cancer cell lines, some of them being phosphorylated forms. We found that cyclin-dependent kinase 2 phosphorylated Cdx2 in vitro and in vivo. Using site-specific mutagenesis, we identified serine 281 as a new key residue for Cdx2 phosphorylation. Intriguingly, serine 281 belongs to a conserved motif of four evenly spaced serines (the 4S motif) similar to the one controlling beta-catenin degradation by the proteasome pathway. A nonphosphorylated mutant Cdx2 lacking the 4S motif (4S>A) exhibited reduced polyubiquitination upon proteasome inhibition and increased stability compared to wild-type Cdx2. In addition, we found that this mutant was less efficient to suppress colony formation than wild-type Cdx2. Thus, our data highlight a novel post-translational mechanism controlling Cdx2 degradation via phosphorylation and polyubiquitination, which may be of importance for intestinal development and cancer.
Publication types
-
Comparative Study
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Adenocarcinoma / genetics
-
Adenocarcinoma / pathology
-
Alanine / metabolism
-
Alkaline Phosphatase / antagonists & inhibitors
-
Alkaline Phosphatase / metabolism
-
Alkaline Phosphatase / pharmacology
-
Amino Acid Sequence / genetics
-
Amino Acid Substitution
-
Animals
-
CDX2 Transcription Factor
-
COS Cells
-
Caco-2 Cells
-
Chlorocebus aethiops
-
Colonic Neoplasms / chemistry
-
Colonic Neoplasms / genetics*
-
Colonic Neoplasms / pathology
-
Consensus Sequence / genetics
-
Conserved Sequence / genetics
-
Cyclin-Dependent Kinase 2 / metabolism
-
Enzyme Inhibitors / pharmacology
-
Gene Expression Regulation, Neoplastic
-
Genes, Tumor Suppressor*
-
Glycine / metabolism
-
Homeodomain Proteins / chemistry
-
Homeodomain Proteins / genetics
-
Homeodomain Proteins / metabolism*
-
Humans
-
Intestinal Mucosa / drug effects
-
Intestinal Mucosa / metabolism
-
Jejunum / drug effects
-
Jejunum / metabolism
-
Mice
-
Molecular Sequence Data
-
Mutagenesis, Site-Directed
-
Phosphorylation
-
Proteasome Endopeptidase Complex / metabolism*
-
Protein Processing, Post-Translational
-
Sequence Homology, Amino Acid
-
Serine / chemistry
-
Transcription Factors / chemistry
-
Transcription Factors / genetics
-
Transcription Factors / metabolism
-
Transcription, Genetic
-
Ubiquitin / metabolism*
Substances
-
CDX2 Transcription Factor
-
CDX2 protein, human
-
Cdx2 protein, mouse
-
Enzyme Inhibitors
-
Homeodomain Proteins
-
Transcription Factors
-
Ubiquitin
-
Serine
-
CDK2 protein, human
-
Cyclin-Dependent Kinase 2
-
Alkaline Phosphatase
-
Proteasome Endopeptidase Complex
-
Alanine
-
Glycine