Abcg2a 是在斑马鱼血脑屏障表达的人 ABCG2 的功能同源物。
Abcg2a is the functional homolog of human ABCG2 expressed at the zebrafish blood-brain barrier.
机构信息
Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 2108, Bethesda, MD, 20892, USA.
Molecular Histopathology Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD, USA.
出版信息
Fluids Barriers CNS. 2024 Mar 15;21(1):27. doi: 10.1186/s12987-024-00529-5.
BACKGROUND
A principal protective component of the mammalian blood-brain barrier (BBB) is the high expression of the multidrug efflux transporters P-glycoprotein (P-gp, encoded by ABCB1) and ABCG2 (encoded by ABCG2) on the lumenal surface of endothelial cells. The zebrafish P-gp homolog Abcb4 is expressed at the BBB and phenocopies human P-gp. Comparatively little is known about the four zebrafish homologs of the human ABCG2 gene: abcg2a, abcg2b, abcg2c, and abcg2d. Here we report the functional characterization and brain tissue distribution of zebrafish ABCG2 homologs.
METHODS
To determine substrates of the transporters, we stably expressed each in HEK-293 cells and performed cytotoxicity and fluorescent efflux assays with known ABCG2 substrates. To assess the expression of transporter homologs, we used a combination of RNAscope in situ hybridization probes and immunohistochemistry to stain paraffin-embedded sections of adult and larval zebrafish.
RESULTS
We found Abcg2a had the greatest substrate overlap with ABCG2, and Abcg2d appeared to be the least functionally similar. We identified abcg2a as the only homolog expressed at the adult and larval zebrafish BBB, based on its localization to claudin-5 positive brain vasculature.
CONCLUSIONS
These results demonstrate the conserved function of zebrafish Abcg2a and suggest that zebrafish may be an appropriate model organism for studying the role of ABCG2 at the BBB.
背景
哺乳动物血脑屏障（BBB）的主要保护成分是多药外排转运蛋白 P-糖蛋白（P-gp，由 ABCB1 编码）和 ABCG2（由 ABCG2 编码）在内皮细胞腔面的高表达。斑马鱼 P-gp 同源物 Abcb4 在 BBB 中表达，并模拟人类 P-gp。相比之下，关于人类 ABCG2 基因的四个斑马鱼同源物（abcg2a、abcg2b、abcg2c 和 abcg2d）知之甚少。在这里，我们报告了斑马鱼 ABCG2 同源物的功能特征和脑组织分布。
方法
为了确定转运蛋白的底物，我们将每种蛋白稳定表达在 HEK-293 细胞中，并使用已知的 ABCG2 底物进行细胞毒性和荧光外排测定。为了评估转运蛋白同源物的表达，我们使用 RNAscope 原位杂交探针和免疫组织化学相结合的方法来染色成年和幼鱼斑马鱼的石蜡包埋切片。
结果
我们发现 Abcg2a 与 ABCG2 的底物重叠最大，而 Abcg2d 似乎功能上最不相似。我们根据其在 Claudin-5 阳性脑血管中的定位，将 abcg2a 鉴定为唯一在成年和幼鱼斑马鱼 BBB 中表达的同源物。
结论
这些结果证明了斑马鱼 Abcg2a 的保守功能，并表明斑马鱼可能是研究 ABCG2 在 BBB 中的作用的合适模型生物。
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