Neighboring Genes Show Correlated Evolution in Gene Expression

Area of Science:

• Genomics
• Evolutionary Biology
• Gene Expression

Background:

• Gene expression profiles are often assumed to evolve independently of genomic location.
• However, neighboring genes in eukaryotic genomes frequently exhibit similar expression patterns, suggesting chromatin-level influences.
• The autonomy of gene expression evolution, particularly concerning neighboring genes, remains an open question.

Purpose of the Study:

• To investigate whether changes in a focal gene's expression influence the expression evolution of its genomic neighbors.
• To examine the extent and characteristics of this influence in human gene expression evolution since the human-chimp common ancestor.

Main Methods:

• Comparative analysis of human and chimpanzee gene expression data.
• Bayesian estimation to account for ancestral states and expression level variations.
• Assessment of gene expression changes in focal genes and their genomic neighbors across tissues and sexes.

Main Results:

• Changes in a focal gene's expression significantly predict changes in its neighbors' expression across all tissues and sexes.
• This effect is strongest within 100 kb but extends over larger genomic distances.
• Sex-specific expression changes also show genomic clustering.

Conclusions:

• Gene expression evolution is likely influenced by genomic context, challenging the notion of autonomy.
• The phenomenon of "expression piggybacking" suggests that changes in one gene's expression can affect its neighbors, analogous to genetic hitchhiking.
• Chromatin-level control is the probable mechanism driving this coordinated expression evolution.