The transcriptional state of ribosomal RNA gene repeats follows strict epigenetic inheritance in humans.
Hosted by: Dr Nadine Hein
Ribosomal RNA genes, which encode the core components of ribosomes, are organized into tandem repeat arrays in most eukaryotes. A remarkable feature of ‘rDNA’ repeats is that only some are transcribed at any given time. Regulation of rDNA transcriptional state isepigenetically determined, and transcription occurs in the nucleolus. Changes in nucleolar morphology have been associated with malignancy for over a century, typically reflectingincreased rRNA transcription. Here I will examine why increased rRNA transcription mightbe associated with malignancy. I will present results from experiments testing one popular hypothesis, the ‘specialized ribosome’ hypothesis. Our results show that the transcriptional states of individual rDNA repeats are strongly inherited through cell divisions in humans, consistent with the specialized ribosome hypothesis. However, the results also suggest thatrRNA is subject to a novel, unknown form of post-transcriptional regulation. I will speculateon the nature of this regulation.
Austen is a Senior Lecturer in Genetics at the University of Auckland’s School of Biological Sciences. He received his PhD from Massey University in New Zealand, and then held post-doctoral fellowships at Duke University in the US, and the National Institute of Basic Biology in Japan. He was appointed to Assistant Professor at the National Institute of Genetics in Japan, and then returned to New Zealand to take lectureships at Massey University Auckland and then the University of Auckland. He is a past convenor of the Lorne Genome meeting and has been a visiting scientist at the University of Tokyo. His research interests are in understanding the evolutionary dynamics of genomes and the impact these dynamics have on genome function. His group uses both experimental and bioinformatic approaches, with research encompassing organisms ranging from yeast to human. In particular, Austen has a strong focus on the use of the ribosomal RNA gene repeats as a “model” genomic system, including the use of synthetic biology to probe this experimentally recalcitrant region of the genome.