Genetic diversity of human RNase 8

Area of Science:

• Genomics
• Molecular Biology
• Evolutionary Biology

Background:

• Ribonuclease 8 (RNase 8) is a primate-specific secretory ribonuclease, related to RNase 7.
• Unlike RNase 7, RNase 8's physiological function is largely unknown.
• Genetic diversity in human RNase 8 is of interest due to functional pseudogenes in other primates.

Purpose of the Study:

• To investigate the genetic diversity of human RNase 8.
• To explore the expression patterns and potential functional divergence of RNase 8.

Main Methods:

• Quantitative reverse-transcription PCR (RT-PCR) for expression analysis.
• Single-nucleotide polymorphism (SNP) and allele identification.
• Rapid amplification of cDNA ends (RACE) and RT-PCR to identify transcripts.
• Transfection assays in COS-7 cells to confirm translational start site function.

Main Results:

• RNase 8 expression detected in adult human lung, spleen, and testis.
• Low nucleotide sequence diversity (π = 0.00122) with two SNPs and four alleles identified.
• Identified a functional distal translational start site, adding 30 conserved amino acids in higher primates.

Conclusions:

• RNase 8 exhibits unique characteristics, potentially diverging significantly from canonical RNase A family members.
• The functional alternative start site and conserved amino acids suggest a unique biological role.
• Findings necessitate a re-evaluation of primate RNase 8, previously considered a potential pseudogene.