Apoptosis Induced by Zinc Deficiency in Rat Osteoblast: Possible Involvement of Protein Kinase C

Key words: 
• Zinc Deficiency /
• zinc deficiency /
• gel electrophoresis /
• DNA fragmentation /
• flow cytometry /
• fetal rat /
• in order

Abstract: Rat osteoblasts were isolated from the 21-day fetal rat calvarias. The cells were grown in DMEM plus 10% FBS, and were treated for 24 h. With 10 μmol/L TPEN or 10 μmol/L TPEN supplemented with 10 μmol/L Zn2+ . Apoptosis of osteoblasts were measured by flow cytometry, electron microscopy and DNA fragmentation analyzed by gel electrophoresis. In addition, IP3 production and PKC activity were measured in order to show whether they are involved in apoptosis in osteoblast induced by zinc deficiency. The results showed that 10 μmol/L TPEN could induce apoptosis in osteoblast in 24 h. But cells treated with 10 μmol/L TPEN supplemented with 10 μmol/L Zn2+showed no apoptotic changes in 24 h. TPEN significantly reduced the formation of IP3 and PKC activity after 24 h incubation. No differences were observed between the cells treated with TPEN supplemented with Zn2 + simultaneously and the untreated cells. It can be inferred that apoptosis induced by zinc deficiency may be due to the decreased activity of PKC which is impaired by reduced formation of IP3.