A complex selection signature at the human AVPR1B gene.

Area of Science:

• Genetics
• Evolutionary Biology
• Neuroscience

Background:

• The vasopressin receptor type 1b (AVPR1B) gene is primarily found in pituitary corticotropes.
• AVPR1B mediates arginine vasopressin's (AVP) stimulation of ACTH release.
• AVPR1B variations are linked to human mood and anxiety disorders, and receptor gene absence in rodents causes behavioral and stress response alterations.

Purpose of the Study:

• To investigate evidence of natural selection acting on the AVPR1B gene in humans.
• To analyze the genetic diversity and evolutionary pressures on AVPR1B exons.

Main Methods:

• Analysis of the two exons of the AVPR1B gene.
• Examination of nucleotide diversity, allele frequencies, and phylogenetic relationships within human populations.
• Comparison of within-species diversity to interspecific divergence.

Main Results:

• Evidence suggests AVPR1B has undergone natural selection in humans.
• Exon 2 analysis indicates balancing selection in African and European populations, characterized by high nucleotide diversity and excess intermediate-frequency alleles.
• Exon 1 shows unusual features, suggesting directional selection may have acted on a nonsynonymous variant (Gly191Arg).

Conclusions:

• This study presents one of the first examples of a gene associated with mood disorders being subject to natural selection in humans.
• The findings support the hypothesis that mood regulation mechanisms might have conferred an evolutionary advantage.
• Further research is needed to identify the specific selective pressures on the AVPR1B gene.