臺灣博碩士論文加值系統

血基質氧化酵素, 主要是一個分子量32 kDa, 具可誘導性的蛋白質.在血
基質代謝中, 扮演一個速率決定步驟的角色,主要是催化血基質分子轉變
成biliverdin分子. 到目前為止, 有兩種不同形態的血基質氧化酵素被
發現, 分別是血基質氧化酵素-1及血基質氧化酵素-2. 血基質氧化酵
素-1的特性是可以被許多不同性質的誘導物所誘導, 例如, 血基質本身或
其類似物, 重金屬及氧化性的逆境等均會誘導血基質氧化酵素-1的表現.
至於血基質氧化酵素-2, 則不受誘導物的誘導. 在本研究中, 我們利用
reverse transcriptase-PCR的技術, 選殖出一段鼷鼠的血基質氧化酵
素-1的cDNA片段(840 bp), 並且也利用pGEM-T載體, 構建一個含鼷鼠的血
基質氧化酵素-1的cDNA片段的pGEM-HO1質體. 利用北方雜合分析法指
出, 鎘化物的處理的確會誘導血基質氧化酵素-1的mRNA表現, 並且隨鎘的
處理濃度增加而增加. 由動力學的分析指出, 血基質氧化酵素-1的mRNA
表現會在鎘處理4個小時後達到最大表現量. 利用protein kinase C
(PKC)的活化劑phorbol ester (TPA)及抑制劑H-7分別與鎘共同作用, 發
現H-7會抑制由鎘所誘導的血基質氧化酵素-1的mRNA表現, 而TPA則會加強
其表現. 再以無鈣的環境或以鈣離子通透劑A23187與鎘共同處理時, 同
樣也發現, 無鈣環境下,鎘誘導的血基質氧化酵素-1的mRNA表現受抑制,有
A23187時則會加強其表現. 由這些結果暗示, 血基質氧化酵素-1的 mRNA
表現, 可能受細胞內與鈣離子有關的磷酸化酵素活性的調控, 很可能是與
PKC有關.

Heme oxygenase (HO), a 32-kDa stress-induced protein, catalyzes
the oxidation of heme to biliverdin. There are two forms of
the enzyme known as HO-1 and HO-2. HO-1 is induced by
exogenous stimuli such as heme analogues, heavy metals and
oxidative stress, whereas HO-2 is not induced by such stimuli.
We generated the 840 base-pairs HO-1 cDNA by using reverse
transcriptase-PCR (RT-PCR) from sodium arsinate-induced TM3
cells. The HO-1 cDNA was subcloned into pGEM-T vector and the
sequence was determined by the dideoxy chain termination
method. The kinetics and dose-dependent expression of HO-1 mRNA
in CdCl2-treated TM3 cells were studied by Northern blot
analysis. Strong induction of HO-1 mRNA was observed following
CdCl2 treatment and the maximum induction of the HO-1 mRNA was
reached after 4 hours. The accumulation of HO-1 mRNA was
enhanced by the phorbol ester (TPA) and calcium ionophore
A23187, but inhibited by protein kinase C (PKC) inhbitor H-7
and by deprivaion of Ca2+ ions. These results suggest that PKC
is involved in the induction of HO-1 gene expression by CdCl2.