Distribution and regional expression of citrin in human tissues, genetic abnormality and possible role in clinical features of type II citrullinemia

II型瓜氨酸血症是一种常染色体隐性遗传病，其特征是成人起病后反复出现意识障碍和/或因脑病合并高氨血症和严重脑水肿而导致的异常行为。CTLN2患者的组织病理学研究显示，精氨酸琥珀酸合成酶(ASS)严重缺乏肝脏特异性，该酶与肝细胞胞浆氨代谢有关。本病未发现ASS基因突变或基因表达异常。SLC25A13基因突变已被确定为CTLN2的遗传原因。SLC25A13基因编码线粒体溶质载体蛋白Citrin。最近的研究表明，SLC25A13突变也可引起特发性新生儿肝炎(NICCD)。目的：研究Citrin蛋白和信使核糖核酸(Citrin)在人体多器官中的分布和表达。方法：对5例因各种疾病死亡的患者的心脏、肾脏、肝脏、胰腺、骨骼肌、肺和脑进行…检查。更多的爱德。用抗Citrin多克隆抗体进行免疫组织化学染色和原位杂交，以确定详细的区域分布。我们还在人体控制器官中进行了蛋白质印迹。结果：免疫印迹显示，Citrin抗体仅在肝脏和肾脏、胰腺和脑中、肺中、心脏和骨骼肌中检测到一条74 kDa的条带。免疫组织化学显示肝组织肝细胞、近、远端小管上皮细胞、肾组织足细胞、胰腺组织中央腺泡细胞、脑组织星形胶质细胞、肺组织肺泡细胞呈强阳性表达。原位杂交组织化学显示Citrin基因的分布与免疫组织化学结果基本一致。结论：Citrin蛋白和信使核糖核酸在多个器官中的分布有限。Citrin在肝细胞中大量表达，提示Citrin分子功能障碍可能导致高氨性脑病和脂肪肝。我们的研究还表明，星形胶质细胞和中央腺泡细胞上的Citrin功能障碍可能是CTLN2脑病和慢性胰腺炎的促进因素之一。较少

Type II citrullinemia (CTLN2) is autosomal recessive disorder, characterized by adult-onset recurrent consciousness disturbance and/or abnormal behavior due to encephalopathy associated with hyperammonemia and severe brain edema. Histopathological study of CTLN2 patients shows severe liver-specific deficiency of argininosuccinate synthetase (ASS), which relates to ammonia metabolism in cytosole of hepatocytes. No mutations or abnormal mRNA expression in ASS gene have been found in this disorder. Mutations in SLC25A13 gene have been identified as genetic cause of the CTLN2. SLC25A13 gene encodes a mitochondrial solute carrier protein named citrin. Recent study showed that mutation of SLC25A13 also cause idiopathic neonatal hepatitis (NICCD). OBJECTIVE: To examine distribution and regional expression of citrin protein and mRNA in multiple human organs. METHODS: The hearts, kidneys, livers, pancreas, skeletal muscles, lungs and brains from 5 patients died with various diseases were examin … More ed. Detailed regional distributions were determined by immunohistochemistry with using polyclonal antibody to citrin and in situ hybridization. We also conducted western blotting in human control organs. RESULTS: On western blotting, only one band of 74 kDa was detected by the antibody to citrin predominantly in liver and kidney, moderately in pancreas and brain, slightly in lung, but not in heart and skeletal muscle. Immunohistochemistry using the antibody to citrin showed positive staining strongly in hepatocytes of liver tissues, epithelial cells of proximal and distal tubules, and podocyte in kidney tissues, moderately in centroacinar cells of pancreas tissues, astrocytes in brain tissues, and pneumocytes in lung tissues. In situ hybridization histochemistry revealed that mRNA of citrin was showed almost the same distribution in comparison with immunohistochemistry. CONCLUSIONS: Distributions of citrin protein and mRNA were limited in several organs. Citrin was greatly expressed in hepatocyte, indicating that dysfunction of this molecule might cause hyperammonic encephalopathy and fatty liver seen in this disorder. Our study also indicated that citrin dysfunction in astrocytes and centroacinar cells might plays a role of the promotion factor about encephalopathy and chronic pancreatitis in CTLN2. Less