Prodynorphin transcripts and proteins differentially expressed and regulated in the adult human brain
Transcription from multiple promoters along with alternative mRNA splicing constitutes the basis for cell-specific gene expression and mRNA and protein diversity. The prodynorphin gene (PDYN) gives rise to prodynorphin (PDYN), precursor to dynorphin opioid peptides that regulate diverse physiological functions and are implicated in various neuropsychiatric disorders. Here, we characterized PDYN transcripts and proteins in the adult human brain and studied PDYN processing and intracellular localization in model cell lines. Seven PDYN mRNAs were identified in the human brain; two of the transcripts, FL1 and FL2, encode the full-length PDYN. The dominant, FL1 transcript shows high expression in limbic-related structures such as the nucleus accumbens and amygdala. The second, FL2 transcript is only expressed in few brain structures such as the claustrum and hypothalamus. FL-PDYN was identified for the first time in the brain as the dominant PDYN protein product. Three novel PDYNs expressed from spliced or truncated PDYN transcripts either lack a central segment but are still processed into dynorphins, or are translated into N-terminally truncated proteins. One truncated PDYN is located in the cell nucleus, suggesting a novel nonopioid function for this protein. The complexity of PDYN expression and diversity of its protein products may be relevant for diverse levels of plasticity in adaptive responses for the dynorphin system.