[Oct 3]Seminar -Prof. Maria Anisimova -

2023年10月3日(火) 13:00-14:00

微研本館1F 微研ホール

Tandem repeats (TRs) are found abundantly in genomic sequences across all domains of life. they are known to contribute to fundamental biological functions and can be associated with virulence, resistance, and human diseases. A growing body of evidence suggests that natural selection shapes some TR regions. However, studies of repeats are typically non-trivial due to high mutability and heterogeneity of TR regions.  In this talk I will discuss some statistical methods for analysing TRs and present several applications. For example, we analysed TRs with long repeat units (> 10-15 residues) across eukaryotic proteomes. We found that most TRs are ancient, with TR unit number and order preserved since distant speciation events. Presumably, most protein TRs fold into stable and conserved structures that are indispensable for the function of the TR-containing protein.
In contrast, short TRs (STRs, with units of 1–6 bp) are orders of magnitude more mutable than other well-studied genotypic variants; STRs therefore make major contribution to genetic and phenotypic divergence. Our current work shows that STR mutations might regulate gene expression in colorectal cancer (CRC). We derive a set of putative expression STRs (eSTRs) for which the STR copy number is associated with gene expression levels in CRC tumours. 
We show that linear models describing eSTR-gene expression relationships allow for predictions of gene expression changes in response to eSTR mutations. Furthermore, we found an increased mutability of eSTRs in MSI tumours. This may be an early indication that eSTR mutations confer a selective advantage for some CRC tumours. Our evidence of gene regulatory roles for eSTRs in CRC highlights a largely unexplored way through which tumours may modulate their phenotype.