Comparative analysis of estrogen receptor gene polymorphisms in apes

Area of Science:

• Evolutionary genetics
• Primate genomics
• Molecular evolution

Background:

• Polymorphic microsatellite repeats in human estrogen receptor alpha (ESRalpha) promoter and estrogen receptor beta (ESRbeta) intron 6 regions are known.
• Understanding the evolutionary history of these repeats in closely related species is crucial for interpreting their functional significance.

Purpose of the Study:

• To investigate the evolutionary patterns of microsatellite repeats in ESRalpha and ESRbeta genes across great apes and gibbons.
• To determine the origins and diversification of these repeat regions in primate evolution.

Main Methods:

• DNA sequencing of the promoter region of ESRalpha and intron 6 of ESRbeta genes.
• Analysis of microsatellite repeat sequences in samples from chimpanzees, bonobos, gorillas, orangutans, and four gibbon species.

Main Results:

• ESRalpha TA repeats show expansion in great apes, with specific CA dinucleotide expansions appearing in the common ancestor of chimpanzees and bonobos.
• Gibbons possess a shorter TA repeat (TA)(2) in ESRalpha, suggesting a divergence from great apes.
• ESRbeta repeat patterns are highly complex and variable across apes and gibbons, with unique repeat motifs (TATG, TATC) observed in gibbons and a deletion in orangutans.

Conclusions:

• The evolution of ESRalpha microsatellite repeats involved expansions and lineage-specific changes, with CA dinucleotide expansion originating in the chimpanzee-bonobo lineage.
• ESRbeta microsatellite regions exhibit significant structural diversity and rapid evolution across hominoids, indicating distinct evolutionary trajectories.
• These findings provide insights into the dynamic nature of non-coding DNA and its evolution in primates.