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Sp1 DNA binding efficiency is highly reduced in nuclear extracts from aged rat tissues
R Ammendola1, M Mesuraca, T Russo
1Department of Biochemistry and Medical Biotechnology, University of Naples Federico II, Italy.
The Journal of Biological Chemistry
|September 5, 1992
Summary
Aging reduces the DNA-binding efficiency of the Sp1 transcription factor in rat brains and livers, impacting gene expression and potentially contributing to cellular senescence.
Area of Science:
- Molecular Biology
- Aging Research
- Neuroscience
Background:
- Cellular senescence is a complex phenotype influenced by various factors.
- Transcriptional factors play a crucial role in regulating gene expression and cellular processes.
Purpose of the Study:
- To investigate the involvement of specific DNA-binding proteins in the development of the senescent phenotype.
- To analyze age-related changes in transcription factor activity in rat brain nuclear extracts.
Main Methods:
- Gel shift assays were used to assess DNA-binding efficiency of transcription factors.
- Immunoblotting quantified Sp1 protein levels.
- DNase I footprinting analyzed Sp1 binding to specific gene promoters (H ferritin, SV40 early promoter).
Main Results:
- Sp1 DNA-binding efficiency significantly decreased in aged rats (30 months) compared to young rats (4 months).
- CTF/NF1 and AP1 binding efficiencies remained unchanged with age.
- Reduced Sp1 binding correlated with decreased H ferritin mRNA expression (approx. 50%) in aged rat brains.
- This age-related decrease in Sp1 binding was also observed in liver nuclear extracts.
Conclusions:
- The reduced DNA-binding activity of Sp1, not altered protein levels, is a key factor in age-related gene expression changes.
- This diminished Sp1 function may contribute to the senescent phenotype and impact cellular function in aging brains and other tissues.