Accelerated Evolution of Enhancer Hotspots in the Mammal Ancestor. (29th December 2015)

• Record Type: Journal Article
• Authors: Holloway, Alisha K.; Bruneau, Benoit G.; Sukonnik, Tatyana; Rubenstein, John L.; Pollard, Katherine S.
• Is Part Of: Molecular biology and evolution. Volume 33:Number 4(2016:Apr.)
• Page Start: 1008
• Page End: 1018
• Publication Date: 2015-12-29
• Subjects: comparative genomics -- development -- enhancer evolution -- mammal-specific traits; Molecular biology -- Periodicals; Molecular evolution -- Periodicals; Evolution, Molecular -- Periodicals; Molecular Biology -- Periodicals; 572.8
• DOI: 10.1093/molbev/msv344
• Languages: English
• ISSNs: 0737-4038

Abstract

Abstract: Mammals have evolved remarkably different sensory, reproductive, metabolic, and skeletal systems. To explore the genetic basis for these differences, we developed a comparative genomics approach to scan whole-genome multiple sequence alignments to identify regions that evolved rapidly in an ancestral lineage but are conserved within extant species. This pattern suggests that ancestral changes in function were maintained in descendants. After applying this test to therian mammals, we identified 4, 797 accelerated regions, many of which are noncoding and located near developmental transcription factors. We then used mouse transgenic reporter assays to test if noncoding accelerated regions are enhancers and to determine how therian-specific substitutions affect their activity in vivo. We discovered enhancers with expression specific to the therian version in brain regions involved in the hormonal control of milk ejection, uterine contractions, blood pressure, temperature, and visual processing. This work underscores the idea that changes in developmental gene expression are important for mammalian evolution, and it pinpoints candidate genes for unique aspects of mammalian biology.