Transforming growth factor beta 1 (TGF beta 1) reduces cellular levels of p34cdc2, and this effect is abrogated by adenovirus independently of the E1A-associated pRB binding activity

Abraham, S. E., Carter, M. C., Moran, E. (June 1992) Transforming growth factor beta 1 (TGF beta 1) reduces cellular levels of p34cdc2, and this effect is abrogated by adenovirus independently of the E1A-associated pRB binding activity. Mol Biol Cell, 3 (6). pp. 655-665. ISSN 1059-1524 (Print)1059-1524 (Linking)

URL: http://www.ncbi.nlm.nih.gov/pubmed/1323350
DOI: 10.1091/mbc.3.6.655

Abstract

We have used E1A probes to study the roles of the p34cdc2 kinase and the retinoblastoma tumor susceptibility gene product (pRB) in transforming growth factor beta 1 (TGF beta 1)-mediated growth suppression in mink lung epithelial (Mv1Lu) cells. In agreement with previous reports, we see a decline in p34cdc2 kinase activity and a loss of pRB phosphorylation after TGF beta 1 treatment. We report here that TGF beta 1 induces not only a change in p34cdc2 kinase activity but a strong repression of p34cdc2 synthesis. Loss of p34cdc2 kinase activity is not seen until the steady-state level of p34cdc2 declines, suggesting that the intra-cellular signals induced by TGF beta 1 affect p34cdc2 at the level of expression, rather than by altering the posttranslational modifications of p34cdc2 that regulate its kinase activity. Infection with adenovirus expressing either wild-type E1A or a mutant E1A (pm928) defective for pRB binding alleviated TGF beta 1-mediated suppression of DNA synthesis, indicating that E1A does not need to bind pRB physically to keep cell growth-suppressing functions from being activated by TGF beta 1. The E1A.928 mutant virus is able to maintain p34cdc2 expression and kinase activity, as well as pRB phosphorylation in the presence of TGF beta 1, which may account for its ability to maintain cell cycle activity without directly sequestering pRB. Overall our results suggest that TGF beta 1 acts by signaling changes at the level of control of G1 gene expression, not at the level of posttranslational modification of p34cdc2 or its substrates.

Item Type: Paper
Uncontrolled Keywords: Adenoviridae/*physiology Adenovirus Early Proteins Animals CDC2 Protein Kinase/antagonists & inhibitors/metabolism/*physiology Cell Division/physiology Cell Line DNA/biosynthesis Kinetics Mink Oncogene Proteins, Viral/metabolism Phosphorylation Protamine Kinase/metabolism Retinoblastoma Protein/*metabolism Transforming Growth Factor beta/*physiology
Subjects: organism description > virus > adenovirus
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > cdc2
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein expression > phosphorylation
CSHL Authors:
Communities: CSHL labs
Depositing User: Matt Covey
Date: June 1992
Date Deposited: 28 Sep 2015 20:51
Last Modified: 28 Sep 2015 20:51
PMCID: PMC275620
Related URLs:
URI: http://repository.cshl.edu/id/eprint/31816

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