Talk by Janne Turunen on U12-dependent splicing. – University of Copenhagen

Talk by Janne Turunen on U12-dependent splicing.

On 9 February 2015 at 11.00-12.00 Janne Turunen from Karolinska Institut Stockholm will give a talk at Thorvaldsensvej 40, 1871 Frederiksberg C, room H117-3. The topic of the talk is: U12-dependent splicing - an evolutionarily conserved mechanism for post-transcriptional gene regulation.

Abstract: Two different types of introns are present in eukaryotic pre-mRNAs, known as U2 and U12-type introns, or major and minor introns, respectively. Recent bioinformatic studies have revealed that U12-type introns are present in a wide range of eukaryotic organisms, and are even found conserved in homologous positions in distantly related organisms, such as plants and animals.

However, U12-type introns comprise only a small portion (less than 1 %) of all introns in any given organism. Their removal, which is catalyzed by the specific U12-dependent spliceosome, is also less efficient than the removal of U2-type introns. Why, then, is U12-splicing conserved in a large number of organisms? The likely answer is that the reduced efficiency of U12-dependent splicing functions as a mechanism to control the expression of a specific set of genes in certain tissues and/or developmental stages. Indeed, U12-dependent splicing is necessary for the survival of the organisms with U12-type introns, and mutations in U12-type splicing factors lead to severe developmental defects in these organisms.

Furthermore, recent studies have also shown that the activity of the U12-dependent spliceosome itself is carefully regulated by feedback mechanisms and in response to external stimuli. One such regulatory mechanism functions through nonsense-mediated decay of U12-type splicing factor mRNAs, and is induced by alternative splicing. The sequence elements controlling these alternative splicing events are extremely conserved, present in both animals and plants, highlighting the ancient origin and importance of mechanisms regulating U12-dependent splicing.

For more information, see: Turunen et al. (2013) "The significant other: splicing by the minor spliceosome" WIREs RNA 4:61–76