Osmotic regulation of Na-myo-inositol cotransporter mRNA level and activity in endothelial and neural cells.
Osmotic regulation of Na-myo-inositol cotransporter mRNA level and activity in endothelial and neural cells.
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DOI：
10.1152/ajpcell.1996.270.4.c990
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发表时间：
1996-04
期刊：
影响因子：
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通讯作者：
T. J. Wiese;J. Dunlap;C. Conner;J. Grzybowski;W. Lowe;M. Yorek
中科院分区：
文献类型：
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作者：
T. J. Wiese;J. Dunlap;C. Conner;J. Grzybowski;W. Lowe;M. Yorek
肌醇（MI）是合成磷酸肌醇的重要因子，作为渗透剂，MI有助于调节细胞体积。在肾源性细胞中，高渗导致钠依赖性MI转运蛋白（SMIT）mRNA水平和MI转运增加。然而，它是未知的，是否渗透压的变化调节MI在神经或内皮细胞的运输。在这些研究中，将神经细胞和内皮细胞暴露于高渗培养基长达48小时，并确定对MI转运的影响。细胞在高渗介质中暴露24 h可最大程度地增加MI的转运。高亲和力MI运输的动力学分析表明，增加的表观最大速度，没有显着变化的表观Km。MI运输的高渗诱导被封锁的放线菌酮，表明蛋白质合成的要求，并与SMIT mRNA水平的增加。与高渗的影响相反，神经和内皮细胞暴露于低渗条件下导致SMIT mRNA水平和MI运输内皮细胞中的减少。这些研究表明，在肾外细胞类型中，渗透压的变化也调节SMIT活性和mRNA水平。
Myo-inositol (MI) is an important factor in the synthesis of phosphoinositides, and as an osmolyte, MI contributes to the regulation of cell volume. In cells of renal origin, hypertonicity causes an increase in sodium-dependent MI transporter (SMIT) mRNA levels and MI transport. However, it is unknown whether changes in osmolarity regulate transport of MI in neural or endothelial cells. IN these studies, neural and endothelial cells were exposed to hyperosmotic medium for up to 48 h, and the effect on MI transport was determined. Transport of MI was maximally increased by exposing the cells to hyperosmotic medium for 24 h. Kinetic analysis of high-affinity MI transport demonstrated an increase in the apparent maximal velocity with no significant change in the apparent Km. The hyperosmotic induction of MI transport was blocked by the addition of cycloheximide, indicating a requirement for protein synthesis, and was associated with increased levels of SMIT mRNA. In contrast to the effect of hypertonicity, exposure of neural and endothelial cells to hypotonic conditions caused a decrease in SMIT mRNA levels and MI transport in endothelial cells. These studies demonstrate that, in extrarenal cell types, changes in osmolarity also regulate SMIT activity and mRNA levels.