Back to Search
Start Over
Translation inhibition during cell cycle arrest and apoptosis: Mcl-1 is a novel target for RNA binding protein CUGBP2.
- Source :
-
American journal of physiology. Gastrointestinal and liver physiology [Am J Physiol Gastrointest Liver Physiol] 2008 Apr; Vol. 294 (4), pp. G1025-32. Date of Electronic Publication: 2008 Feb 21. - Publication Year :
- 2008
-
Abstract
- CUGBP2, a translation inhibitor, induces colon cancer cells to undergo apoptosis. Mcl-1, an antiapoptotic Bcl-2 family protein, interferes with mitochondrial activation to inhibit apoptosis. Here, we have determined the effect of CUGBP2 on Mcl-1 expression. We developed a HCUG2 cell line by stably expressing CUGBP2 in the HCT-116 colon cancer cells. HCUG2 cells demonstrate decreased levels of proliferation and increased apoptosis, compared with HCT-116 cells. Flow cytometry analysis demonstrated higher levels of cells in the G(2)-M phase. Western blot analyses demonstrated that there was decreased Bcl-2 and Mcl-1 protein but increased expression of Bax, cyclin B1, and Cdc2. Immunocytochemistry also demonstrated increased levels of cyclin B1 and Cdc2 in the nucleus of HCUG2 cells. However, there was colocalization of phosphorylated histone H3 with transferase-mediated dUTP nick-end labeling (TUNEL). Furthermore, immunostaining for alpha-tubulin demonstrated that there was disorganization of microtubules. These data suggest that CUGBP2 expression in HCUG2 cells induces the cells to undergo apoptosis during the G(2)-M phase of the cell cycle. We next determined the mechanism of CUGBP2-mediated reduction in Mcl-1 expression. Mcl-1 protein, but not Mcl-1 mRNA, was lower in HCUG2 cells, suggesting translation inhibition. CUGBP2 binds to Mcl-1 3'-untranslated region (3'-UTR) both in vitro and in HCUG2 cells. Furthermore, CUGBP2 increased the stability of both endogenous Mcl-1 and luciferase mRNA containing the Mcl-1 3'-UTR. However, luciferase protein expression from the luciferase-Mcl-1 3'-UTR mRNA was suppressed. Taken together, these data demonstrate that CUGBP2 inhibits Mcl-1 expression by inhibiting Mcl-1 mRNA translation, resulting in driving the cells to apoptosis during the G(2) phase of the cell cycle.
- Subjects :
- 3' Untranslated Regions
Blotting, Western
CDC2 Protein Kinase
CELF Proteins
Cell Proliferation
Colonic Neoplasms enzymology
Colonic Neoplasms genetics
Colonic Neoplasms pathology
Cyclin B metabolism
Cyclin B1
Cyclin-Dependent Kinases
Flow Cytometry
Genes, Reporter
HCT116 Cells
Histones metabolism
Humans
Immunohistochemistry
Mitosis
Myeloid Cell Leukemia Sequence 1 Protein
Neoplasm Proteins genetics
Nerve Tissue Proteins genetics
Phosphorylation
Protein Binding
Proto-Oncogene Proteins c-bcl-2 genetics
RNA Processing, Post-Transcriptional
RNA Stability
RNA, Messenger metabolism
RNA-Binding Proteins genetics
Transfection
Tubulin metabolism
bcl-2-Associated X Protein metabolism
Apoptosis genetics
Cell Cycle genetics
Colonic Neoplasms metabolism
Gene Expression Regulation, Neoplastic
Neoplasm Proteins metabolism
Nerve Tissue Proteins metabolism
Protein Biosynthesis
Proto-Oncogene Proteins c-bcl-2 metabolism
RNA-Binding Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0193-1857
- Volume :
- 294
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- American journal of physiology. Gastrointestinal and liver physiology
- Publication Type :
- Academic Journal
- Accession number :
- 18292181
- Full Text :
- https://doi.org/10.1152/ajpgi.00602.2007