- 學位論文
GATA-3對骨母細胞骨鈣素基因表現之角色研究
ROLES OF GATA-3 IN REGULATION OF OSTEOCALCIN GENE EXPRESSION IN RAT OSTEOBLASTS
摘要
骨母細胞(osteoblasts)參與在骨頭形成期(bone formation)，骨鈣素(osteocalcin)是其中一種小分子且能跟鈣離子結合的指標蛋白，已有研究證實很多刺激因子能刺激骨母細胞表現骨鈣素以及促進其礦物化其中包含了維他命C，很多研究證明了骨鈣素的表現受到了許多轉錄因子的調節，轉錄因子GATA-3在T淋巴球細胞中高度表現並且能調節許多不同的基因促進細胞的分化，在先前的研究證實了骨母細胞能藉由調節轉錄因子GATA-3保護細胞避免氧化壓力的傷害，也有報告指出維他命C能刺激間葉幹細胞分化為心肌細胞藉由調節轉錄因子GATA-4。因此本篇研究想進一步探討維他命C是否會藉由轉錄因子GATA-3調節骨鈣素的表現在骨母細胞礦物化過程中。 實驗結果顯示骨母細胞培養在含有 100 μg/ml 維他命C以及5 mM β-glycerophosphate下14天之後，可以觀察到礦物化的形成，另外偵測到骨鈣素基因的表現量會增加在維他命C刺激24小時之下；另外以核醣核酸干擾技術將骨母細胞內轉錄因子GATA-3表現量降低之後也發現到骨母細胞骨鈣素表現量隨之降低；對於維他命C所誘導的骨鈣素的表現也隨骨母細胞內轉錄因子GATA-3表現量降低也有抑制的情形，使用不同的MAPK的抑制劑前處理細胞後，發現維他命C所刺激的骨鈣素基因的表現會受到MAPK中的p38以及ERK兩條訊息傳遞所影響。 綜合以上結果，結論為維他命C會刺激骨母細胞礦物化以及藉由p38和ERK訊息傳遞以及轉錄因子GATA-3造成骨鈣素基因的表現。
並列摘要
Osteoblasts are involved in bone formation and have a critical role in bone remodeling. Osteocalcin is an important marker protein for binding calcium in mineralization phase. There are many factors that stimulate osteoblast mineralization and osteocalcin expression, one of which is ascorbic acid. There are also considerable evidences proving that osteocalcin expression is mediated by many transcription factors. Transcription factor GATA-3 is highly expressed in T cells and can regulate different marker genes to promote T cells’ differentiation. Previous studies have also shown that ascorbic acid can stimulate the differentiation of MS Cells into cardio-myocyte with GATA-4. In our laboratory, transcription factor GATA-3 can regulate Bax/Bcl-XL to protect osteoblasts from oxidative stress-induced cell damage. Therefore, this study wants to elucidate that transcription factor GATA-3 can be a mediator of osteocalcin expressions leading to mineralization when osteoblast is treated with ascorbic acid. Our data shows that osteoblast mineralization is detected when osteoblasts are incubated in medium containing 100 μg/ml ascorbic acid and 5 mM β-glycerophosphate for 14 days. The data has also shown that ascorbic acid has a time-depending effect on osteocalcin expression, and that both basal level and ascorbic acid-induced osteocalcin expressions decrease while GATA-3 is knocked down from osteoblasts. The data has also shown that ascorbic acid stimulates osteocalcin expression via p38 and ERK in MAPK (mitogen- activated protein kinase) cascade. In conclusion, ascorbic acid can promote osteoblast mineralization and stimulate osteocalcin expression via MAPK and transcription factor GATA-3.
參考文獻
延伸閱讀
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