Pseudogenization of the tumor-growth promoter angiogenin in a leaf-eating monkey

Area of Science:

• Evolutionary Biology
• Genetics
• Primate Physiology

Background:

• Gene-knockout studies in model organisms like mice are crucial for understanding human gene function.
• Challenges arise when gene duplication and functional redundancy occur, complicating genotype-phenotype correlations.
• Angiogenin, a protein involved in blood vessel growth and tumor development, presents such a challenge due to differing gene copy numbers between humans and mice.

Purpose of the Study:

• To investigate the physiological role of angiogenin in primates using an evolutionary approach.
• To identify natural gene inactivation events that could serve as functional models for human genes.
• To assess the dispensability of primate angiogenin in a wild setting.

Main Methods:

• Comparative genomics and sequencing of the angiogenin gene in douc langurs (Pygathrix nemaeus) and related colobine species.
• Identification of genetic variations, specifically premature stop codons, within the angiogenin gene.
• Analysis of the evolutionary history and species-specific fixation of identified genetic mutations.

Main Results:

• A single-nucleotide deletion in the sixth codon of the mature angiogenin peptide was identified in douc langurs, creating a premature stop codon.
• This deletion was present in multiple unrelated douc langur individuals, indicating it is fixed in the species.
• Intact angiogenin genes were found in closely related colobine species, suggesting a recent, lineage-specific pseudogenization event in douc langurs.

Conclusions:

• The douc langur serves as a natural model for angiogenin knockout, demonstrating that primate angiogenin is dispensable in the wild.
• Evolutionary analysis is vital for biomedical research, offering unique insights into gene function and potential therapeutic targets.
• Further studies on douc langur physiology can illuminate the role of angiogenin in primate and human health.