Cultured Astrocytes and Neurons Synthesize and Secrete Carboxypeptidase E, a Neuropeptide‐Processing Enzyme

Marie‐Hélène ‐H Vilijn, Banasree Das, John A. Kessler, Lloyd D. Flicker

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Abstract: Carboxypeptidase E (EC 3.4.17.10) is a carboxy‐peptidase B‐like enzyme associated with the biosynthesis of many peptide hormones and neurotransmitters. Media collected from cultured astrocytes contain a carboxypeptidase E‐like activity. Cultured astrocytes secrete ∼73% of their cellular level of carboxypeptidase E per hour, and secretion is not substantially influenced by 35 mM KCI. In contrast, neurons secrete only 29% of their cellular carboxypeptidase E per hour, but secretion increases to 86% on stimulation with 35 mM KCI. Secretion of carboxypeptidase E activity from both neuronal and astrocyte cultures is relatively selective; neither acid phosphatase or acetylglucosaminidase is secreted in appreciable amounts. Cultured neurons and astrocytes express a carboxypeptidase E mRNA of a similar size. The levels of this mRNA differ in astrocytes cultured from different brain regions, with high levels in striatal, cortical, hippocampal, and hypothalamic astrocytes and low levels in cerebellar astrocytes. The level of carboxypeptidase E mRNA in hypothalamic astrocyte cultures is four‐ to fivefold higher than the level in hypothalamic neuronal cultures. These results indicate that cultured astrocytes express carboxypeptidase E mRNA and enzymatic activity and thus contain one of the enzymes required in the biosynthesis of many peptide hormones and neurotransmitters.

Original languageEnglish (US)
Pages (from-to)1487-1493
Number of pages7
JournalJournal of Neurochemistry
Volume53
Issue number5
DOIs
StatePublished - Nov 1989

Keywords

  • Carboxypeptidase B‐like enzyme
  • Carboxypeptidase E
  • Carboxypeptidase H
  • Enkephalin convertase
  • Neuropeptide processing

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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