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Possible relationship of poly(A) shortening to mRNA turnover
Abstract:
Whereas the original size of poly(A) in HeLa cells is about 200 nucleotides, at steady state most of the poly(A) in mRNA contains less than 50 nucleotides. An endonucleolytic attack on poly(A) is suggested as the most likely method to accumulate short pieces of poly(A). Both poly(A) shortening and mRNA turnover appear to be inhibited by emetine, a drug that stops translation. It is possible that a random endonucleolytic attack leads to scission of poly(A) to a size below which the mRNA is unstable.
Insights
Poly(A) tail shortening in mRNA occurs via endonucleolytic attack, leading to shorter poly(A) tails. Emetine drug inhibits both poly(A) shortening and mRNA turnover by stopping translation.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Poly(A) tails are crucial for mRNA stability and translation.
- The initial size of poly(A) in HeLa cells is approximately 200 nucleotides.
- At steady state, most mRNA poly(A) tails are significantly shorter than their original length.
Purpose of the Study:
- To investigate the mechanism of poly(A) tail shortening in mRNA.
- To understand the role of endonucleolytic activity in poly(A) processing.
- To explore the effect of translation inhibition on poly(A) metabolism and mRNA turnover.
Main Methods:
- Analysis of poly(A) tail length in HeLa cells.
- Investigation of mRNA turnover rates.
- Treatment with emetine, a translation inhibitor.
Main Results:
- Most poly(A) tails in steady-state mRNA are less than 50 nucleotides.
- Endonucleolytic attack is the proposed mechanism for generating short poly(A) fragments.
- Emetine treatment inhibits both poly(A) shortening and mRNA turnover.
Conclusions:
- Poly(A) tail shortening is likely mediated by random endonucleolytic cleavage.
- Translation inhibition by emetine stabilizes mRNA by preventing poly(A) shortening.
- A critical poly(A) length threshold may exist, below which mRNA becomes unstable.