Primate-specific spliced PMCHL RNAs are non-protein coding in human and macaque tissues

Area of Science:

• Evolutionary biology
• Genomics
• Neuroscience

Background:

• Primate-specific genes are key to understanding human neural evolution.
• PMCHL1 originated from a pro-melanin-concentrating hormone (PMCH) antisense mRNA retroposition event.
• PMCHL1 duplicated to form PMCHL2 in hominid ancestors, with complex RNA patterns in human brain and testis.

Purpose of the Study:

• To investigate the gene structure and evolutionary history of primate-specific chimeric PMCHL genes.
• To characterize novel PMCHL transcripts and their evolutionary conservation.
• To determine the protein-coding potential of PMCHL transcripts.

Main Methods:

• Phylogenetic analysis of PMCHL genes in non-human primates.
• Identification and sequencing of novel spliced PMCHL transcripts.
• Western blot analysis to detect PMCHL-encoded proteins.

Main Results:

• Novel spliced PMCHL transcripts with an additional exon and splice sites were identified in human testis and fetal brain.
• Phylogenetic analysis dated the initial retroposition event to 30-35 Mya, coinciding with platyrrhine/catarrhine divergence and AluSg element insertion.
• Spliced PMCHL transcripts contained short ORFs (<300 bp) with low or no evolutionary conservation; no corresponding proteins were detected via Western blot.

Conclusions:

• The study enhances understanding of the structure and evolution of primate-specific PMCHL genes.
• PMCHL genes produce multiple spliced transcripts with short, non-conserved ORFs.
• These transcripts may function as mRNA-like non-coding RNAs, potentially influencing primate neural evolution.