Ma Z J, Yamaguchi M
Laboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, Japan.
Calcif Tissue Int. 2001 Sep;69(3):158-63. doi: 10.1007/s00223-001-2010-1.
The effect of zinc on in vitro deoxyribonucleic acid (DNA) synthesis activity in the femoral-diaphyseal and metaphyseal tissues of newborn rats was investigated to determine a role of zinc in bone growth. In vitro DNA synthesis was assayed in a reaction mixture containing the 100 g centrifugation supernatant, which includes the nucleus of bone cells, of bone issue homogenate with incorporation of [3H]-deoxythymidine 5'-triphosphate (dTTP). DNA synthesis activity in the femoral-diaphyseal and metaphyseal tissues of newborn rats was significantly raised with increasing age (1-21 days) after birth. The presence of dipicolinate (10(-3) M), a chelator of zinc, in the reaction mixture caused a significant decrease in DNA synthesis activity in the diaphyseal and metaphyseal tissues of newborn rats at 7 and 14 days after birth. The addition of zinc sulfate (10(-6) - 10(-4) M) resulted in a significant increase in DNA synthesis activity in the diaphyseal and metaphyseal tissues. When the diaphyseal and metaphyseal tissues of newborn rats at 7 days after birth were cultured for 24 hours in a serum-free medium containing either vehicle, zinc sulfate (10(-4) M), insulin-like growth factor-I (IGF-I; 10(-8) M) or transforming growth factor-beta (TGF-beta; 10(-10) M), bone DNA synthesis activity was significantly elevated. Culture with both zinc and IGF-I enhanced additively bone DNA synthesis activity. Such an effect was not seen in the case of zinc and TGF-beta. The effect of zinc, IGF-I, or zinc plus IGF-I in increasing bone DNA synthesis activity was completely prevented by culture with PD98059 (10(-5) M), an inhibitor of mitogen-activated protein (MAP) kinase. Also, the effect of zinc, TGF-beta. or zinc plus TGF-beta in elevating bone DNA synthesis activity was significantly inhibited by culture with staurosporine (10(-6) M), an inhibitor of protein kinase C. The present study demonstrates that zinc, like bone growth factors, has a stimulatory effect on bone DNA synthesis in newborn rats.
为确定锌在骨骼生长中的作用，研究了锌对新生大鼠股骨干和干骺端组织体外脱氧核糖核酸（DNA）合成活性的影响。在含有100 g离心上清液（包括骨细胞的细胞核）的反应混合物中，通过掺入[3H]-脱氧胸苷5'-三磷酸（dTTP）来测定体外DNA合成，该离心上清液来自骨组织匀浆。新生大鼠股骨干和干骺端组织中的DNA合成活性在出生后随着年龄增长（1 - 21天）显著升高。反应混合物中锌螯合剂吡啶二羧酸（10(-3) M）的存在导致新生大鼠在出生后7天和14天时骨干和干骺端组织中的DNA合成活性显著降低。添加硫酸锌（10(-6) - 10(-4) M）导致骨干和干骺端组织中的DNA合成活性显著增加。当出生后7天的新生大鼠的骨干和干骺端组织在含有溶剂、硫酸锌（10(-4) M）、胰岛素样生长因子-I（IGF-I；10(-8) M）或转化生长因子-β（TGF-β；10(-10) M）的无血清培养基中培养24小时时，骨DNA合成活性显著升高。锌和IGF-I共同培养可增强骨DNA合成活性。锌和TGF-β共同培养则未观察到这种效果。用丝裂原活化蛋白（MAP）激酶抑制剂PD9,8059（10(-5) M）培养可完全阻止锌、IGF-I或锌加IGF-I增加骨DNA合成活性的作用。同样，用蛋白激酶C抑制剂星形孢菌素（10(-6) M）培养可显著抑制锌、TGF-β或锌加TGF-β提高骨DNA合成活性的作用。本研究表明，锌与骨生长因子一样，对新生大鼠的骨DNA合成具有刺激作用。
