Ascorbic acid decreases neutral endopeptidase activity in cultured osteoblastic cells

• Published in: Regulatory peptides 2005-08, Vol.130 (1), p.57-66
• Main Authors: Schmid, Christoph, Ghirlanda-Keller, Claudia, Gosteli-Peter, Martina
• Format: Article
• Language: English
• Subjects: Alkaline Phosphatase - metabolism; Animals; Ascorbic acid; Ascorbic Acid - metabolism; Ascorbic Acid - pharmacology; Biological and medical sciences; Blotting, Northern; Blotting, Western; Calcium - metabolism; Cell Membrane - metabolism; Cell Proliferation; Cells, Cultured - cytology; Dexamethasone - pharmacology; DNA - metabolism; Dose-Response Relationship, Drug; Fundamental and applied biological sciences. Psychology; Growth; Insulin-Like Growth Factor I - pharmacology; NEP; Neprilysin - chemistry; Neprilysin - pharmacology; Osteoblasts; Osteoblasts - cytology; Osteoblasts - metabolism; Peptides - chemistry; Rats; Signal Transduction; Subcellular Fractions; Thiorphan - pharmacology; Thymidine - chemistry; Thymidine - metabolism; Time Factors; Transcriptional Activation; Vertebrates: endocrinology
• ISSN: 0167-0115; 1873-1686
• DOI: 10.1016/j.regpep.2005.03.007

Neprilysin (NEP) is a plasma membrane-bound peptidase with wide expression in kidney, lung, brain and bone. Decreased NEP activity has been linked to increased growth of some cancer cells, but it is unknown whether its activity is related to growth of cells belonging to the osteoblast lineage. We assessed NEP activity in an osteoblastic cell line, PyMS, by cleavage of N-Dansyl- d-Ala-Gly- p-nitro-Phe-Gly to Dansyl- d-Ala-Gly. NEP activity was completely blocked by 1 μM thiorphan. Most agents affecting growth of these cells (e.g. calcium, insulin-like growth factor I and dexamethasone) did not regulate NEP activity. Ascorbic acid (ASA) increased thymidine incorporation into DNA and potentiated the stimulatory effect of IGF I on DNA synthesis, an effect which was attenuated by echistatin. ASA decreased NEP activity in a dose-dependent manner, and decreased Western-detectable NEP protein in plasma membranes. ASA affects both integrin receptor-mediated signalling and the processing of regulatory peptides.