Molecular pathological study on the expression of Metallothionein gene in the brain of aged dog.

我们分离并测定了犬金属硫蛋白-I（MT-I）和MT-III的cDNA全序列，预测的犬MT-III的氨基酸序列具有很高的同源性犬MT-III相对于已知的哺乳动物MT-I和MT-II具有两个插入：第四个氨基酸后的苏氨酸和靠近羧基末端的六个氨基酸的嵌段。我们合成了犬MT-III的特异性多肽（Cys-Lys-Gly-Gly-Glu-Gly-Thr-Glu-Ala-Glu-Glu-Glu-Lys），制备了犬MT-III的多克隆抗体。MT-III免疫组化也支持这一发现。原位杂交显示MT-I表达的年龄相关性增加，而MT-III显示在出生时通过大脑表达。MTs的表达与淀粉样蛋白沉积之间无相关性。

We have isolated and determined the complete nucleotide sequence of canine metallothionein-I (MT-I) and MT-III cDNA.The predicted amino acid sequence of the canine MT-III showed a high homology (93%, 87% identity) to that of human and mouse MT-III.The canine MT-III had two insertions relative to known mammalian MT-I and MT-II : a threonine after the fourth amino acid and a block of six amino acids near the carboxyl terminus. Following sysnthesis of a polypeptide specific for canine MT-III (Cys-Lys-Gly-Gly-Glu-Gly-Thr-Glu-Ala-Glu-Alu-Glu-Lys), we have generated a polyclonal antibody canine MT-III.Expression of the canine MT-III mRNA was found exclusively in the central nervous system, where neurons in the olfactory bulb, hippocampus, thalamus and cerebral cortex showed predominant signals. The findings were also supported by the MT-III immunohistochemistry. In situ hybridization demonstrated age-related increases of MT-I expression, whereas MT-III was shown to be expressed through the brain at birth. There was no relationship between the MTs expression and amyloid deposition.