Poster Presentation 44th Lorne Genome Conference 2023

Mechanisms of intronic trinucleotide repeat expansion in A. thaliana (#207)

Giulia Folini 1 , Sridevi Sureshkumar 1
  1. Monash University, Clayton South, VIC, Australia

Microsatellites are a common type of repetitive sequence found in all eukaryotic genomes. An abrupt expansion in their sequence, particularly at triplet repeats, results in many neuronal genetic disorders, like Huntington's and Friedreich’s ataxia. Friedreich’s ataxia is caused by a GAA/TTC triplet repeat expansion, in the first intron of the FXN gene, that impedes the transcription. A similar phenomenon was discovered in the Arabidopsis thaliana ecotype called Bur-0. Bur-0 plants look perfectly normal when grown at 23 °C but at elevated temperatures (27 °C) they displayed misshapen leaves and growth impairment. This phenotype is caused by a GAA/TTC expansion, in the 3rd intron of IIL1 gene, that causes downregulation.

My project aims are to explore the mechanisms involved in triplet repeat expansion and decipher the genetic and molecular pathways involved in regulating the triplet repeat-mediated gene silencing at the IIL1 locus.

  1. Sureshkumar, S., Todesco, M., Schneeberger, K., Harilal, R., Balasubramanian, S., & Weigel, D. (2009). A Genetic Defect Caused by a Triplet Repeat Expansion in Arabidopsis thaliana. Science, 323(5917), 1060–1063. https://doi.org/10.1126/science.1164014
  2. Eimer, H., Sureshkumar, S., Singh Yadav, A., Kraupner-Taylor, C., Bandaranayake, C., Seleznev, A., Thomason, T., Fletcher, S. J., Gordon, S. F., Carroll, B. J., & Balasubramanian, S. (2018). RNA-Dependent Epigenetic Silencing Directs Transcriptional Downregulation Caused by Intronic Repeat Expansions. Cell, 174(5), 1095-1105.e11. https://doi.org/10.1016/j.cell.2018.06.044