Wouldn’t we all like to have a decoy, a look-alike who could stand in for us during life’s unpleasant moments? You know, like being forced to watch the “Dancing with the Stars” finale, or standing in line for 6+ hours at the DMV? A research effort spear-headed by Laura Poliseno at Beth Israel Deaconess Medical Center found that transcribed pseudogenes, long considered merely “junk” DNA, can sometimes take the fall for protein-coding transcripts targeted by miRNAs.
Pseudogenes resemble normal genes, but aren’t translated into functional proteins because of premature stop codons or other mutations. Many pseudogenes are transcribed into RNA, which suggested to the authors that they may compete for miRNAs targeted to their fully functional cousins, a novel role completely separate from its lack of protein coding abilities. Backing up their hypothesis, the researchers found:
- RNA transcribed from the PTENP1 pseudogene acts a decoy for miRNAs targeting the PTEN tumor suppressor mRNA.
- Overexpression of PTENP1 slows cell proliferation.
- The PTENP1 locus is lost in some cancers
- A similar decoy effect was observed for KRASP1, a pseudogene of the oncogene KRAS
These findings indicate that pseudogenes themselves could function as tumor suppressors or oncogenes by protecting their ancestral protein-coding genes from miRNAs. The researchers speculate that other noncoding RNAs and even mRNA transcripts could serve similar roles as miRNA decoys. Give your decoy the day off, and go read this paper for yourself at Nature, June 2010.