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Expression of p190A during apoptosis in the regressing rat ventral prostate
C Morrissey1, S Bennett, E Nitsche
1Department of Biological Sciences, University of Notre Dame, Indiana 46556, USA.
Abstract:
After hormonal ablation, 90% of the secretory epithelial cells of the prostate undergo apoptosis, and the remaining cells are reorganized as the tissue is remodeled. Using differential display RT-PCR of total RNA extracted from the rat ventral prostate before and 4 days after castration, we have cloned and sequenced a number of complementary DNAs whose cognate messenger RNAs (mRNAs) may be either up- or down-regulated during prostatic regression. One sequence of particular interest, 25.2, is up-regulated after castration and is homologous to p190, a protein associated with cytoskeletal reorganization. RT-PCR has confirmed that the steady state level of p190A mRNA is increased in the rat ventral prostate after castration, and Western blot analysis indicates that the protein levels for p190A also increase. The steady state level of p190B mRNA, the second isoform of p190, does not appear to change significantly after hormone ablation. Immunohistochemical analysis demonstrates that p190A is up-regulated primarily in the columnar epithelial cells that actively undergo cell death after hormone ablation. As Rho-GAP signaling had been shown to be influenced by p190 levels, leading to the disassembly of focal adhesion contacts and the loss of cytoskeletal architecture, we also measured the changes in Rho-GAP during prostate regression. Rho-GAP levels do not change significantly, suggesting that changes in stoichiometry of the interaction between p190A and Rho-GAP may be a prerequisite for the initiation of cytoplasmic condensation. These intracellular events coupled with the proteolytic degradation of the extracellular matrix appear to be integral to the apoptotic process in glandular epithelia.
Insights
Hormonal ablation triggers prostate cell death, increasing p190A protein levels crucial for cytoskeletal reorganization during apoptosis. This suggests altered p190A and Rho-GAP interactions initiate programmed cell death in prostate tissue.
Area of Science:
- Cell Biology
- Molecular Biology
- Prostate Cancer Research
Background:
- Hormonal ablation causes significant prostate epithelial cell apoptosis and tissue remodeling.
- Understanding the molecular mechanisms of apoptosis in prostate regression is critical.
Purpose of the Study:
- To identify genes and proteins involved in prostate regression following hormonal ablation.
- To investigate the role of p190, a cytoskeletal protein, in prostate apoptosis.
Main Methods:
- Differential display RT-PCR to identify differentially expressed mRNAs.
- RT-PCR and Western blot to confirm changes in p190A mRNA and protein levels.
- Immunohistochemistry to localize p190A expression.
- Measurement of Rho-GAP levels during prostate regression.
Main Results:
- A cDNA sequence, 25.2, homologous to p190, was found to be upregulated after castration.
- p190A mRNA and protein levels significantly increased in the rat ventral prostate post-castration.
- p190A was primarily upregulated in columnar epithelial cells undergoing apoptosis.
- Rho-GAP levels remained relatively unchanged, suggesting altered p190A/Rho-GAP stoichiometry.
Conclusions:
- p190A upregulation is a key event in prostate epithelial cell apoptosis following hormonal ablation.
- The interaction between p190A and Rho-GAP may be critical for initiating apoptotic events like cytoplasmic condensation.
- These molecular changes, alongside extracellular matrix degradation, are integral to glandular epithelial apoptosis.