Large scale comparison of global gene expression patterns in human and mouse

Area of Science:

• Comparative genomics
• Gene expression analysis
• Systems biology

Background:

• Orthologous genes are typically conserved in sequence and function across species.
• The conservation of gene expression patterns for orthologous genes remains largely unclear.

Purpose of the Study:

• To investigate the conservation of gene expression patterns for orthologous genes between humans and mice.
• To determine if tissue-specific expression is conserved across species.

Main Methods:

• Comparative analysis of gene expression data from 2,557 human and 1,267 mouse samples.
• Utilized data from the ArrayExpress public microarray repository.
• Employed principal component analysis (PCA) on orthologous probesets.

Main Results:

• Human and mouse samples clustered distinctly by tissue type (nervous system, muscle/heart, liver, cell lines) in PCA.
• Overall expression patterns showed striking similarity between human and mouse tissues.
• Highly variable genes were enriched with tissue-specific orthologs, while least variable genes were enriched with housekeeping orthologs.

Conclusions:

• Global patterns of tissue-specific gene expression are conserved between humans and mice.
• Groups of orthologous genes exhibit co-varying expression in both species.
• Conservation extends to both highly variable and ubiquitously expressed genes.