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Identification and characterization of neutral endopeptidase (EC 3. 4. 24. 11) from human prostasomes–localization in prostatic tissue and cell lines
Author(s) -
Renneberg Heiner,
Albrecht Martin,
Kurek Ralf,
Krause Eberhard,
Lottspeich Friedrich,
Aumüller Gerhard,
Wilhelm Beate
Publication year - 2001
Publication title -
the prostate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.295
H-Index - 123
eISSN - 1097-0045
pISSN - 0270-4137
DOI - 10.1002/1097-0045(20010215)46:3<173::aid-pros1021>3.0.co;2-f
Subject(s) - apocrine , neprilysin , immunoelectron microscopy , immunogold labelling , endopeptidase , stromal cell , biology , immunohistochemistry , microbiology and biotechnology , glycoprotein , secretion , immunocytochemistry , antigen , antibody , prostate , epithelium , chemistry , biochemistry , enzyme , endocrinology , cancer , cancer research , immunology , genetics , anatomy
Background An antibody directed against a 100 kDa protein was immunoselected from a polyvalent antiserum against human prostasomes. The antibody as well as biochemical characteristics of the respective antigen were used to study the structural relationship of the latter with prostate membrane specific antigen (PMSA), another 100 kDa membrane protein of the prostate. Methods The isolated purified 100 kDa protein was characterized by tryptic degradation, aminoacid‐sequencing and mass spectroscopy peptide‐fingerprinting as well as mono‐saccharide analysis and lectin binding and identified as a prostasomal neutral endopeptidase (NEP, EC 3.4.24.11). Immunohistochemistry, immunoelectron microscopy, in situ hybridization, and RT‐PCR were performed to analyze the expression and distribution of the protein in normal and malignant human prostatic tissues and cell lines. Results Prostatic NEP, which has no relationship with PMSA, is a glycosylated, integral membrane protein type II. The prevalent glycosyl residues are NeuNAc, GlcNAc, GalNAc, Gal, Man, Fuc. NEP‐mRNA is expressed in human prostatic epithelial and some stromal cells. NEP‐immunoreactivity is strong in normal prostatic epithelium and confined to the apical plasma membrane. During apocrine secretion, the enzyme is released from the secretory cells, contributing to the formation of prostasomes. In prostate cancer specimens, immunoreactivity of apical plasma membranes is lost, while generalized cytoplasmic immunoreactivity develops. Conclusions Prostatic secretory cells contain a membrane‐bound, highly glycosylated neutral endopeptidase which is restricted to the apical plasma membrane. The enzyme is released from the cells in an apocrine fashion and contributes to the formation of prostasomes. In prostate cancer cells a preferential cytoplasmic localization is observed, pointing to alterations in intracellular targeting. Prostate 46:173–183, 2001. © 2001 Wiley‐Liss, Inc.