Altered processing of pro-orphanin FQ/nociceptin and pro-opiomelanocortin-derived peptides in the brains of mice expressing defective prohormone convertase 2.
The bioactivity of neuropeptides can be regulated by a variety of post-translational modifications, including proteolytic processing. Here, gene-targeted mice producing defective prohormone convertase 2 (PC2) were used to examine the post-translational processing of two neuroendocrine prohormones, pro-opiomelanocortin (POMC) and pro-orphanin FQ (pOFQ)/nociceptin (N), in the brain. Reversed-phase HPLC and gel-exclusion chromatography were combined with specific radioimmunoassays to analyze the processing patterns of these two prohormones in the hypothalamus and the amygdala. In the case of POMC, the lack of PC2 activity completely prevented carboxy-shortening of beta-endorphins and greatly diminished conversion of beta-lipotropin to gamma-lipotropin and beta-endorphin. Although conversion of beta-lipotropin to beta-endorphin decreased, the lack of PC2 activity caused an increase in beta-lipotropin and beta-endorphin levels in the mutant animals, but no increases in POMC or biosynthetic intermediates were seen. The extent of OFQ/N production was significantly lower in PC2-deficient mice and there was an accumulation of relatively large amounts of pOFQ/N and biosynthetic intermediates. These results demonstrate that PC2 is directly involved in the biogenesis of two brain neuropeptides in vivo and suggest that the specific prohormone and cellular context influences neuropeptide processing by PCs.
Allen
R G
RG
Neuroscience and Cell Biology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA. allenr@ohsu.edu
Peng
B
B
Pellegrino
M J
MJ
Miller
E D
ED
Grandy
D K
DK
Lundblad
J R
JR
Washburn
C L
CL
Pintar
J E
JE
D000679:Amygdala / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D018390:Gene Targeting; D006579:Heterozygote; D006720:Homozygote; D007031:Hypothalamus / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011333:Pro-Opiomelanocortin / Q000378:metabolism*; D045706:Proprotein Convertase 2; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011863:Radioimmunoassay; D011957:Receptors, Opioid / Q000378:metabolism*; D013381:Subtilisins / Q000096:biosynthesis* / Q000235:genetics; D001615:beta-Endorphin / Q000096:biosynthesis; D008083:beta-Lipotropin / Q000096:biosynthesis / Q000378:metabolism
D011498:Protein Precursors; D011957:Receptors, Opioid; C119224:pronociceptin; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D008083:beta-Lipotropin; D013381:Subtilisins; D045706:Proprotein Convertase 2