Isolation and characterization of VGF peptides in rat brain. Role of PC1/3 and PC2 in the maturation of VGF precursor

• Published in: Journal of neurochemistry 2002-05, Vol.81 (3), p.565-574
• Main Authors: Trani, E., Giorgi, A., Canu, N., Amadoro, G., Rinaldi, A. M., Halban, P. A., Ferri, L., Possenti, R., Schininà†, M. E., Levi, A.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Aspartic Acid Endopeptidases - genetics; Aspartic Acid Endopeptidases - metabolism; Binding Sites - physiology; Biological and medical sciences; Brain - cytology; Brain - metabolism; Brain Chemistry; Cells, Cultured; Electrophoresis, Polyacrylamide Gel; endoproteolytic processing; Fundamental and applied biological sciences. Psychology; Humans; Isolated neuron and nerve. Neuroglia; MALDI‐ToF mass spectrometry; Mice; Molecular Sequence Data; Molecular Weight; Neurons - cytology; Neurons - metabolism; Neuropeptides; Peptide Fragments - chemistry; Peptide Fragments - isolation & purification; Peptide Fragments - metabolism; Pituitary Gland - cytology; Pituitary Gland - metabolism; prohormone convertase; Proprotein Convertase 1; Proprotein Convertase 2; Proprotein Convertases; Protein Precursors - metabolism; Protein Processing, Post-Translational - physiology; Proteins - metabolism; rat brain; Rats; Sequence Analysis, Protein; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Subtilisins - genetics; Subtilisins - metabolism; Transfection; Vertebrates: nervous system and sense organs; VGF peptides
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.2002.00842.x

The neurotrophin responsive gene vgf is widely expressed in central and peripheral neurones, and in certain neuroendocrine cell populations. Its encoded VGF precursor protein (proVGF1: 617 amino acids in rat, 615 in man, > 85% homology) gives rise to several low molecular weight species. We studied a range of neuroendocrine and neuronal cells, in which VGF‐processing products were prominent with an apparent molecular weight of 20 and 10 kDa (VGF20 and VGF10, respectively). Such peptides were recognized by antibodies specific for the C‐terminal rat VGF nonapeptide, thus indicating that they included the C‐terminus of proVGF. Ectopic expression of the neuroendocrine‐specific prohormone convertases PC1/3 or PC2 in GH3 cells showed that both could generate VGF20, while VGF10 was preferentially produced by PC1/3. Site‐directed mutagenesis was used to identify the KRKRKK488 motif as the target within VGF sequence which leads to the production of VGF20. Molecular characterization of rat VGF10, on the other hand, revealed that this peptide is produced by cleavage at the RPR555 site. By the combined use of high‐resolution separation techniques, matrix‐assisted laser desorption/ionization time of flight (MALDI‐ToF) mass spectrometry and manual Edman degradation we identified in rat brain a VGF fragment analogous to bovine peptide V and two novel peptides also derived from the C‐terminal region of proVGF.