Expression of Drosophila melanogaster P-glycoproteins is associated with ATP channel activity
Expression of Drosophila melanogaster P-glycoproteins is associated with ATP channel activity
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DOI：
10.1152/ajpcell.1996.271.5.c1527
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发表时间：
1996-11-01
影响因子：
5.5
通讯作者：
Cantiello, HF
中科院分区：
文献类型：
--
作者：
Bosch, I;Jackson, GR;Cantiello, HF
先前已经鉴定了两种不同染色体来源的果蝇P-糖蛋白（Pgp）基因同源物，MDR 49和MDR 65（38）。大多数Pgps与多药耐药表型的发展有关。尽管在鉴定与Pgp功能相关的分子机制方面进行了大量努力，但这些转运分子的内源性底物在很大程度上是未知的。本实验室最近的研究表明，鼠Pgp同源物（E. H. Abraham，A. G.普拉湖Gerweck，T.塞内韦拉特纳河J. Arceci，R.克雷默，G. Guidotti和H. F.坎蒂罗Proc. Natl. Acad. Sci. USA 90：312-316，1993）和相关蛋白质，囊性纤维化跨膜传导调节因子（CFTR; I. L. Reisin，A.普拉，E. H.亚伯拉罕，J.F.阿马拉河J. Gregory，D. A. Ausiello和H. F.坎蒂罗J.Biol.Chem.269：20584-20591，1994）是新颖的ATP可渗透离子通道。这两种蛋白质的共同特征是保守的ATP结合盒（ABC）;因此结构上与ABC转运蛋白家族相连的分子也可能在功能上与ATP通道活性相关。在这项研究中，MDR 65和MDR 49 Pgps的功能性表达的Sig细胞，和膜片钳技术应用于评估这些蛋白在ATP的电扩散运动的作用。在细胞内ATP和外部NaCl的存在下，MDR 65的表达与ATP和Cl-都可渗透的线性电扩散通路相关。在对称ATP条件下，只有电压去极化激活MDR 65介导的ATP传导通路。MDR 49的表达也与对称ATP中电压激活的ATP电导相关，但在不对称条件下观察到对Cl-或ATP没有明显的渗透性。MDR 65和MDR 49的不同功能特性可能指示在该生物体中的不同生理作用。然而，这项研究表明，这两个果蝇Pgp同源物与它们的哺乳动物亲属Pgp和CFTR具有很强的功能相似性。
Two distinct Drosophila melanogaster P-glycoprotein (Pgp) gene homologues of different chromosomal origin, MDR49 and MDR65, have been previously identified (38). Most Pgps are implicated in the development of the multidrug-resistance phenotype. Despite intense efforts to identify the molecular mechanism(s) associated with Pgp function, the endogenous substrate(s) of these transport molecules is largely unknown. Recent studies from our laboratory indicate that a murine Pgp homologue (E. H. Abraham, A. G. Prat, L. Gerweck, T. Seneveratne, R. J. Arceci, R. Kramer, G. Guidotti, and H. F. Cantiello. Proc. Natl. Acad. Sci. USA 90: 312-316, 1993) and a related protein, the cystic fibrosis transmembrane conductance regulator (CFTR; I. L. Reisin, A. Prat, E. H. Abraham, J. F. Amara, R. J. Gregory, D. A. Ausiello, and H. F. Cantiello. J. Biol. Chem. 269: 20584-20591, 1994), are novel ATP-permeable ion channels. The common feature of these two proteins is the conserved ATP-binding cassettes (ABC); thus molecules structurally linked to the ABC transporter family may be also functionally associated with ATP channel activity. In this study, MDR65 and MDR49 Pgps were functionally expressed in Sig cells, and patch-clamp techniques were applied to assess the role of these proteins in the electrodiffusional movement of ATP. In the presence of intracellular ATP and external NaCl, expression of MDR65 was associated with a linear electrodiffusional pathway that was permeable to both ATP and Cl-. Under symmetrical ATP conditions, only voltage depolarization activated a MDR65-mediated ATP-conductive pathway. Expression of MDR49 was also associated with a voltage-activated ATP conductance in symmetrical ATP, but no apparent permeability to either Cl- or ATP was observed under asymmetrical conditions. The different functional properties of MDR65 and MDR49 may be indicative of distinct physiological roles in this organism. The study indicates, however, that the two Drosophila Pgp homologues share strong functional similarities with their mammalian relatives Pgp and CFTR.