In Vitro Selections for Lanthanide Aptamers

The aim of this project is to develop a specific luminescent tracer of RNA by means of in vitro selection for short RNA oligonucleotides (aptamers) that bind lanthanide metals. Lanthanides are luminescent elements that absorb light poorly on their own, but are capable of receiving energy, transferred from an antenna molecule that can absorb light. An RNA aptamer for lanthanides could serve as an antenna enabling energy transfer from RNA to the metal, thus enhancing luminescence. A luminescent RNA aptamer has the potential to be used as a molecular genetics tool for quantifying expression levels of RNA, as well as observing localization of tagged RNA transcripts. In addition, a lanthanide-RNA complex can be used for other applications, such as nuclear magnetic resonance. Lanthanides are paramagnetic and are capable of inducing relaxation and chemical shift changes in surrounding RNA spins, and can induce partial magnetic alignment of the whole RNA. Selections have been performed for several lanthanide-aptamer complexes. Clones of individual RNA aptamers are being tested for binding and luminescence enhancement of lanthanides complexes. These lanthanide-aptamer complexes have many promising advantages over commonly used fluorescent or luminescent tools to observe RNA and provide a novel approach to temporal and spatial tracking of RNA in vivo.