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Effect of tetracycline on collagen biosynthesis in cultured embryonic bones

1969; Elsevier BV; Volume: 18; Issue: 4 Linguagem: Inglês

10.1016/0006-2952(69)90053-7

1873-2968

Jouko Halme, Kari I. Kivirikko, Ilkka Kaitila, Lauri Saxén,

dental development and anomalies

The biosynthesis of collagen was studied with 14C-proline in organ cultures of embryonic ulnae. The rate of conversion of the incorporated 14C-proline to 14C-hydroxyproline in cultured ulnae was optimal up to 6 days, provided that the medium contained ascorbate and was replaced daily. When the medium was not replaced daily, the rate of 14C-proline incorporation was reduced to about 60 per cent, and only a small part of the incorporated 14C-proline was converted to 14C-hydroxyproline. In these conditions, a considerable part of the 14C-proline was found to be in the form of protocollagen, the proline-rich and hydroxyproline-deficient polypeptide precursor of collagen. The addition of 10, 30 or 100 μgml tetracycline to the culture medium reduced the rate of incorporation of 14C-proline into protein. The rate of 14C-hydroxyproline synthesis was reduced even more, and thus a decrease was observed in the conversion of the incorporated 14C-proline to 14C-hydroxyproline. Similar changes were observed when embryonic ulnae from pregnant mice receiving tetracycline were cultured in a medium not containing tetracycline. In experiments with purified protocollagen hydroxylase, tetracycline was found to inhibit the hydroxylation of 14C-proline-labelled protocollagen, the degree of inhibition being dependent on the concentration of ferrous iron in the reaction mixture. Cultivation of the ulnae with tetracycline had no effect on the total amount of protocollagen hydroxylase activity in the bones when the determination was made in the presence of excess of ferrous iron. The results suggest that tetracycline inhibits collagen synthesis by inhibiting both the incorporation of proline into protocollagen and the conversion of protocollagen to collagen. The latter inhibition is probably due to an interaction of tetracycline with ferrous iron, which is required in the hydroxylation of proline by protocollagen hydroxylase.