Differential splicing of transcripts encoding the orphanin FQ/nociceptin precursor

Area of Science:

• Molecular Biology
• Neuroscience
• Genetics

Background:

• Orphanin FQ/nociceptin (OFQ/N) is a peptide agonist for the NOP receptor, synthesized from a precursor protein, preproOFQ/N.
• Alternative splicing of the mouse OFQ/N transcript between exons 3 and 4 has been previously reported, leading to precursor proteins with varied C-termini.

Purpose of the Study:

• To investigate alternative splicing of preproOFQ/N transcripts in humans and rats.
• To identify novel human splice variants and analyze their potential impact on protein structure and function.

Main Methods:

• Reverse transcription polymerase chain reaction (RT-PCR) was used to analyze preproOFQ/N transcripts.
• In vitro translation of cRNAs was performed to study the products of novel splice variants.

Main Results:

• Alternative splicing between exons 3 and 4 of preproOFQ/N transcripts was confirmed in humans and rats.
• Two novel human preproOFQ/N splice variants were identified, characterized by the excision of exon 2 and alternative splicing between exons 3 and 4.
• In vitro translation of exon 2-deficient transcripts produced shorter proteins initiated from an alternative methionine within exon 3, lacking a signal peptide.

Conclusions:

• The identified alternative splicing events in human and rat preproOFQ/N transcripts suggest conserved regulatory mechanisms.
• Novel human splice variants lacking exon 2 may lead to proteins with altered signal peptide sequences, impacting cellular localization and processing.
• These findings contribute to understanding the molecular diversity and regulation of OFQ/N precursor protein production.