The Molecular and Genomic Evolution of the Relaxin Gene Cluster in Hominoid Primates
Bayer School of Natural and Environmental Sciences
Relaxin, parturition, human evolution, labor, hominoid, selection
Relaxin is a peptide hormone expressed during pregnancy whose function is to degrade connective tissue at the pubic symphysis and soften the cervix in preparation for birth. During evolution, the expansion of the human brain created a problem unique among hominoids: passage of a large fetal skull through a pelvic inlet designed for bipedal locomotion. Relaxin may have evolved to play a key role in the adaptations necessary to solve this problem. Humans and the great apes possess the relaxin cluster, consisting of RLN1, RLN2 and INSL4. Comparative analyses were used to examine the mode of sequence evolution in these genes, in order to test the hypothesis that positive selection has driven their evolution. Since this cluster arose as the result of multiple duplication events, we determined the number of putatively functional relaxin genes in each species in the study and characterized gene conversion events in the hominoids. Lastly, comparative computational analysis of regulatory elements critical for expression of the relaxin genes were evaluated for changes that might alter the expression pattern of both genes. Observed changes in regulatory elements have been interpreted in a phylogenetic context, and under the hypothesis that evolution of the relaxin promoter regions may be responsible for adaptations related to human birth.
Brockway, H. (2007). The Molecular and Genomic Evolution of the Relaxin Gene Cluster in Hominoid Primates (Master's thesis, Duquesne University). Retrieved from https://dsc.duq.edu/etd/1719