Participation of chicken GGAAA repeat in sex differentiation

Tandem repeating elements that form extended polypurine/polypyrimidine tract sequences have been found in the genomes of various species. Their structural properties bend the DNA helix and cause a transition to non-canonical DNA secondary structures. The modern scientific literature describes many examples of the involvement of such elements in the regulation of gene expression and the formation of alternative transcripts in cells of different types of differentiation (Matos-Rodrigues et al., 2023). Previously, we described the (GGAAA)n repeating element of chicken (Gallus gallus domesticus), which is predominantly localized on the sex chromosome W and makes up about 1% of the female genome (Komissarov et al., 2018). Here we describe the localization peculiarities of this tandem repeat in the chicken genome within autosomes and the sex chromosome Z. The study identified a number of genes carrying tandemly repeated (GGAAA)n elements within non-coding transcribed regulatory regions that can influence expression intensity and the formation of alternative transcripts. Functional characterization of genes carrying stacks of (GGAAA)n allowed us to suggest the involvement of these tandem repeats in regulating the differential activity of genes important for the development of sexual dimorphism traits in chicken.