In Vitro Massively Parallel Screening of Human Regulatory Elements Involved in Postcranial Skeletal Development for...

Area of Science:

• Evolutionary biology
• Genomics
• Human origins

Background:

• Human skeletal features distinguish us from chimpanzees, influencing key evolutionary developments like bipedalism and brain size.
• Identifying the genetic underpinnings of these skeletal differences is challenging due to extensive human-chimp genome divergence.

Purpose of the Study:

• To pinpoint human-chimp sequence variations that affect gene expression in the developing human skeleton.
• To understand the regulatory mechanisms driving human skeletal evolution.

Main Methods:

• Utilized a massively parallel reporter assay (MPRA) to screen 70,000 regulatory elements for differential activity between human and chimpanzee genomes.
• Tested regulatory element activity in cartilage and control cell lines.

Main Results:

• Identified 30,736 (45.2%) active regulatory regions, with 11,542 (17% of total) showing differential activity between humans and chimpanzees.
• Human Ancestor Quickly Evolved Regions (HAQERs) predicted differential activity, unlike Human Accelerated Regions.
• The total number of base pair differences weakly correlated with effect size, suggesting a polygenic model.

Conclusions:

• Human skeletal evolution is characterized by widespread regulatory changes across numerous elements, rather than localized effects at a few loci.
• This polygenic model provides a framework for understanding the genetic basis of human skeletal adaptations.