Evolutionary Innovations in Conserved Regulatory Elements Associate With Developmental Genes in Mammals

Area of Science:

• Evolutionary biology
• Genomics
• Developmental biology

Background:

• Transcriptional enhancers control cell-specific gene expression.
• Genetic variations in enhancers contribute to phenotypic diversity, adaptation, and disease.
• The scale and patterns of regulatory evolution across mammalian phylogeny remain largely unexplored.

Purpose of the Study:

• To investigate patterns of accelerated sequence evolution in conserved mammalian enhancers.
• To identify genes and pathways enriched for regulatory evolution.
• To understand the functional consequences of enhancer evolution.

Main Methods:

• Large-scale comparative genomics analysis of conserved enhancer elements across mammalian species.
• Identification of signatures of accelerated sequence evolution.
• Functional analysis of specific enhancer evolution events, including HES1.

Main Results:

• A significant pattern of accelerated enhancer evolution was observed across the mammalian phylogeny.
• Pleiotropic genes involved in gene regulation and development were disproportionately enriched for accelerated enhancer evolution.
• Sequence acceleration in enhancers was linked to regulatory function turnover, exemplified by HES1 enhancer evolution associated with digit reduction.

Conclusions:

• Enhancer evolution is a common mechanism for regulatory innovation in conserved developmental genes in mammals.
• Pleiotropic genes with multiple enhancer connections are hotspots for regulatory evolution.
• Specific enhancer evolutionary events can coincide with major phenotypic adaptations.