Mouse glucose transporter 9 splice variants are expressed in adult liver and kidney and are up-regulated in diabetes
Mouse glucose transporter 9 splice variants are expressed in adult liver and kidney and are up-regulated in diabetes
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DOI：
10.1210/me.2005-0010
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发表时间：
2006-03-01
影响因子：
--
通讯作者：
Moley, KH
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文献类型：
--
作者：
Keembiyehetty, C;Augustin, R;Moley, KH
新发现的葡萄糖转运蛋白(GLUT)--小鼠GLUT9(MGLUT9)是最近从小鼠7-d胚胎中克隆的。描述了mGLUT9的几个剪接变体，其中两个被克隆(mGLUT9a和mGLUT9a((Delta 209-316)。本研究描述了另一种剪接变异体mGLUT9b的克隆和鉴定。从成人肝脏中克隆的mGLUT9b与mGLUT9a完全相同，只是在氨基末端。根据对基因组结构的分析，不同的氨基末端是由不同的转录/翻译起始点造成的。研究了这两种mGLUT9剪接变异体在正常和糖尿病成年小鼠组织和细胞系中的表达和定位。RT-PCR分析显示mGLUT9a在多种组织中表达，而mGLUT9b主要在肝脏和肾脏中表达。使用mGLUT9特异性抗体，对肝脏和肾脏的总膜部分进行Western印迹分析，检测到一条单一的、宽的条带，大约在55 kDa处迁移。当用多肽-N-糖苷酶F脱糖时，这条带移动到较低的分子质量，这两种形式都存在于肝脏和肾脏中。免疫组织化学定位显示mGLUT9在肝细胞内呈基底侧方分布，在肾脏外皮质的特定小管中有表达。在肾上皮细胞系中过表达mGLUT9a和mGLUT9b。亚细胞组分将这两种形式定位于质膜。偏振的Madin Darby犬肾细胞过度表达mGLUT9的免疫荧光染色显示两种剪接变体的基本侧向分布。最后，与非糖尿病小鼠相比，链脲佐菌素诱导的糖尿病小鼠肾脏和肝脏中mGLUT9蛋白的表达显著增加。
A novel glucose transporter (GLUT), mouse GLUT9 (mGLUT9), was recently cloned from mouse 7-d embryonic cDNA. Several splice variants of mGLUT9 were described, two of which were cloned (mGLUT9a and mGLUT9a ((Delta 209-316))). This study describes the cloning and characterization of another splice variant, mGLUT9b. Cloned from adult liver, mGLUT9b is identical to mGLUT9a except at the amino terminus. Based on analysis of the genomic structure, the different amino termini result from alternative transcriptional/ translational start sites. Expression and localization of these two mGLUT9 splice variants were examined in control and diabetic adult mouse tissues and in cell lines. RT-PCR analysis demonstrated expression of mGLUT9a in several tissues whereas mGLUT9b was observed primarily in liver and kidney. Using a mGLUT9-specific antibody, Western blot analysis of total membrane fractions from liver and kidney detected a single, wide band, migrating at approximately 55 kDa. This band shifted to a lower molecular mass when deglycosylated with peptide-N-glycosidase F. Both forms were present in liver and kidney. Immunohistochemical localization demonstrated basolateral distribution of mGLUT9 in liver hepatocytes and the expression of mGLUT9 in specific tubules in the outer cortex of the kidney. To investigate the alternative amino termini, mGLUT9a and mGLUT9b were overexpressed in kidney epithelium cell lines. Subcellular fractions localized both forms to the plasma membrane. Immunofluorescent staining of polarized Madin Darby canine kidney cells overexpressing mGLUT9 depicted a basolateral distribution for both splice variants. Finally, mGLUT9 protein expression was significantly increased in the kidney and liver from streptozotocin-induced diabetic mice compared with nondiabetic animals.