Expression and processing of human preprogastrin in murine medullary thyroid carcinoma cells.
Gastrin, the primary hormonal mediator of postprandial gastric acid secretion, is produced from its precursor progastrin by a series of posttranslational processing reactions including dibasic residue cleavage and carboxyl-terminal alpha-amidation. Progastrin contains three dibasic cleavage signals, Arg57Arg58, Lys74Lys75, and Arg94Arg95, that appear to be cleaved differently in different tissues. Differential processing is a potential means by which the production of biologically active peptides may be regulated in a tissue-specific manner. To study these reactions further, we used the pZipNeo SV(X) retroviral vector to express human gastrin cDNA in a heterologous cell line (MTC 6-23) known to be capable of processing other peptide precursors. The psi 2 packaging cell line transfected with the gastrin cDNA-retroviral construct (pSVXgas) produced progastrin, but no substantial amounts of processed amidated gastrin were detected. amounts of processed amidated gastrin were detected. In contrast, MTC 6-23 cells infected with the viral stock obtained from the supernatant of pSVXgas-transfected psi 2 cells produced carboxyl-terminally amidated gastrin in all of its standard molecular forms, including sulfated and nonsulfated forms of tetratriacontagastrin (G-34), heptadecagastrin (G-17), and tetradecagastrin (G-14). These studies indicate that heterologous endocrine cell lines infected with a retroviral-peptide cDNA construct can serve as useful models for peptide hormone posttranslational processing.
Daugherty
D F
DF
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109.
Dickinson
C J
CJ
Takeuchi
T
T
Bachwich
D
D
Yamada
T
T
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D005755:Gastrins / Q000032:analysis / Q000235:genetics* / Q000302:isolation & purification; D015870:Gene Expression; D005822:Genetic Vectors; D006801:Humans; D007124:Immunoenzyme Techniques; D051379:Mice; D008969:Molecular Sequence Data; D010957:Plasmids; D011061:Poly A / Q000235:genetics / Q000302:isolation & purification; D011498:Protein Precursors / Q000235:genetics*; D011499:Protein Processing, Post-Translational; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger; D011863:Radioimmunoassay; D015183:Restriction Mapping; D013964:Thyroid Neoplasms; D014162:Transfection
D005755:Gastrins; D011498:Protein Precursors; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; C042873:preprogastrin