Evolution of the MYB Gene Family of Transcription Factors

Undergraduate #90
Discipline: Biological Sciences
Subcategory: Genetics

Justin Jones - Saint Augustine's University
Co-Author(s): Mike W. Vandewege and Federico G. Hoffmann, Mississippi State University, Starkville, MS

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The MYB protein family is a group of transcription factors that regulates the expression of several target genes. Studies based on mouse identified one member of the MYB family, A-MYB, as one of the major transcription factors regulating the expression of PIWI interacting (piRNA) clusters. These clusters act as the source of piRNAs, a class of small RNAs involved in protecting genome integrity by repressing the activity of transposable elements. At present, there is great interest in elucidating how piRNAs are regulated, expressed, and processed. A reconstruction of the evolutionary history of the MYB family can shed light on when the association between A-MYB and piRNA clusters emerged. To do this we first queried MYB nucleotide sequences from both vertebrate and invertebrate genomes, and reconstructed the evolutionary history using phylogentic methods. With a few notable exceptions, MYBs were generally absent from invertebrate genomes. Interestingly, the expansion of the MYB family is notable in the early stages of vertebrate evolution: The presence of three MYB paralogs, A-MYB, B-MYB and C-MYB maps to the early branches of the vertebrate tree. Although the trees would suggest the duplications giving rise to these genes are shared between cyclostomes and gnathostomes, the former have lost traces of A-MYB. Our results would indicate that the involvement of A-MYB in regulating the expression of piRNA clusters might trace back to the common ancestor of teleost fish and tetrapods, approximately 400 million years ago.

Funder Acknowledgement(s): National Science Foundation

Faculty Advisor: Mark Melton,