title: Mononuclear cell supernatants inhibit prolyl hydroxylation.
abstract: The effect of phytohemagglutinin(PHA)-activated human peripheral mononuclear cell supernatant (AS) on collagen production by human fibroblasts was examined. The AS inhibited collagen production in a dose- and time-dependent manner. Labeling and pulse chase experiments showed that it did not block collagen secretion, but a greater proportion of molecules synthesized in its presence accumulated within the cells. Amino acid analysis showed that when labeling was done at 24 degrees C prolyl hydroxylation in fibroblasts exposed to the AS was reduced to two-thirds of the cultures treated with control supernatant (CS), however it was not different at 37 degrees C. These results indicate that the AS inhibits collagen hydroxylation, that the un-(under)hydroxylated collagen molecules are degraded at physiological temperature and that suppression of collagen hydroxylation may be a mechanism by which the AS inhibits collagen production.
mesh_terms: D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis* / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D006900:Hydroxylation; D006909:Hydroxyproline / Q000378:metabolism*; D008214:Lymphocytes / Q000502:physiology*; D009000:Monocytes / Q000502:physiology*; D010835:Phytohemagglutinins / Q000494:pharmacology; D011392:Proline / Q000378:metabolism
chemical_list: D010835:Phytohemagglutinins; D003094:Collagen; D011392:Proline; D006909:Hydroxyproline