Mididoddi S, McGuirt J P, Sens M A, Todd J H, Sens D A
Robert C. Byrd Health Sciences Center, Department of Pathology, West Virginia University, Morgantown 26506, USA.
Toxicol Lett. 1996 Apr;85(1):17-27. doi: 10.1016/0378-4274(96)03632-6.
The organization of the metallothionein (MT) gene family has been demonstrated to be much more complex in humans than in the mouse, and possibly rodents in general. For humans, the MTs are encoded by a family of genes located at 16q13 representing 10 functional and 7 non-functional MT isoforms. In the present study, the 5' and 3' untranslated region sequences of the highly conserved, functional MT genes were utilized to generate primer pairs for the analysis of isoform-specific MT mRNA using reverse transcriptase-polymerase chain reaction (RT-PCR). Human kidneys from 13 weeks gestation through adulthood were examined for the expression of MT protein and mRNA. Immunohistochemical analysis demonstrated MT immunoreactivity to be confined exclusively to the proximal tubules of the adult and developing kidney. For all MT-positive cells, MT was localized in the cytoplasm and nuclear localization was variable. There was no correlation between nuclear staining and stage of development. Of the 10 MT genes examined (MT-1A, MT-1B, MT-1E, MT-1F, MT-1G, MT-1H, MT-1X, MT-2A, MT-3, and MT-4), mRNAs representing the MT-1E, MT-1F, MT-1X, and MT-2A genes were consistently expressed in all samples regardless of gestational age. There was no indication of a 'fetal form' of MT analogous to that noted to occur in human liver. Messenger RNA for the MT-1A gene was detected in 2 of 6 renal samples without correlation to gestational age. In no instance was mRNA for the MT-1B, MT-1G, MT-1H, MT-3 or MT-4 genes detected. These studies detail the initial determination of MT gene expression in the human renal system and provide the PCR primers for testing and determination of MT gene expression in other organ systems.
金属硫蛋白（MT）基因家族的组织方式在人类中已被证明比在小鼠中，甚至可能在一般啮齿动物中更为复杂。对于人类而言，MT由位于16q13的一组基因编码，代表10种功能性和7种非功能性MT异构体。在本研究中，利用高度保守的功能性MT基因的5'和3'非翻译区序列生成引物对，通过逆转录-聚合酶链反应（RT-PCR）分析异构体特异性MT mRNA。对妊娠13周直至成年的人类肾脏进行MT蛋白和mRNA表达检测。免疫组织化学分析表明，MT免疫反应性仅局限于成年和发育中肾脏的近端小管。对于所有MT阳性细胞，MT定位于细胞质，细胞核定位则各不相同。细胞核染色与发育阶段之间无相关性。在所检测的10个MT基因（MT-1A、MT-1B、MT-1E、MT-1F、MT-1G、MT-1H、MT-1X、MT-2A、MT-3和MT-4）中，无论胎龄如何，代表MT-1E、MT-1F、MT-1X和MT-2A基因的mRNA在所有样本中均持续表达。未发现类似于人类肝脏中出现的MT“胎儿形式”的迹象。在6个肾脏样本中的2个中检测到MT-IA基因的信使RNA，与胎龄无关。未检测到MT-1B、MT-1G、MT-1H、MT-3或MT-4基因的mRNA。这些研究详细阐述了人类肾脏系统中MT基因表达的初步测定，并提供了用于检测和测定其他器官系统中MT基因表达的PCR引物。
