Aplysia neurons express a gene encoding multiple FMRFamide neuropeptides.

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• The neuroactive peptide Phe-Met-Arg-Phe-NH2 (FMRF-amide) exhibits diverse effects across mammalian and invertebrate tissues.
• FMRFamide-like immunoreactivity is widespread throughout the animal kingdom, indicating its conserved biological importance.

Purpose of the Study:

• To isolate and characterize a cDNA clone encoding the FMRF-amide precursor protein in Aplysia.
• To investigate the structure, processing, and distribution of FMRF-amide peptides within the Aplysia nervous system.

Main Methods:

• cDNA library screening from Aplysia abdominal ganglion.
• Gene sequencing and analysis.
• Immunohistochemical analysis of peptide distribution.

Main Results:

• A cDNA clone encoding a precursor protein for up to 19 FMRF-amide peptides was isolated and characterized.
• FMRF-amide sequences within the precursor are flanked by Lys-Arg and Gly-Lys residues, suggesting enzymatic cleavage sites.
• The gene exists as a single copy and produces multiple transcripts via alternative splicing.
• Immunohistochemistry revealed widespread FMRF-amide presence in Aplysia neurons projecting to various tissues.

Conclusions:

• A single precursor protein in Aplysia can generate a large family of FMRF-amide peptides.
• The processing of FMRF-amide peptides is regulated by specific flanking residues and alternative RNA splicing.
• FMRF-amide plays a significant role in neuronal signaling across the Aplysia nervous system and its associated tissues.