MicroRNA undermines tumor suppression( FINDINGS: Scientists at the Whitehea...),Health

FINDINGS: Scientists at the Whitehead Institute for Biomedical Research and the National University of Singapore have discovered the first microRNA (miRNA) capable of directly tamping down the activity of the well known tumor-suppressor gene, p53, While p53 functions to prevent tumor formation, the p53 gene is thought to malfunction in more than 50% of cancerous tumors.

RELEVANCE: The study reports the first time a miRNA has been shown to directly affect the p53 protein level, although researchers have previously identified other genes and miRNAs that indirectly affect p53's activity.

CAMBRIDGE, Mass. (March 17, 2009) A small piece of RNA, or microRNA (miRNA), ratchets down the activity of the tumor-suppressor gene p53, according to a study by Whitehead Institute and National University of Singapore researchers.

While p53 functions to suppress tumor formation, the p53 gene is thought to malfunction in more than 50% of cancerous tumors.

The study published online March 17 in Genes and Development reports the first time that a miRNA has been shown to directly affect the p53 gene, although researchers have previously identified other genes and miRNAs that regulate p53's activity indirectly.

"For critical genes like p53, it's important that they are maintained at the right level in the cell," says Beiyan Zhou, a postdoctoral researcher in the lab of Whitehead Member Harvey Lodish and mentor to the paper's first author, Minh Le. "Le's work describes one more layer of regulatory mechanism that balances p53 gene expression."

miRNAs, short snippets of RNA, usually reduce how often a certain gene is translated into a protein. When a miRNA matches with and binds to a given messenger RNA coding for a specific protein, thereby preventing that messenger RNA from acting as a template for protein creation.

To investigate whether any miRNAs directly affect p53, Le, who is a joint graduate student in Lo
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