Involvement of monocarboxylate transporter 7 in taurine efflux transport from rat retinal pericytes and capillary endothelial cells

IF 2.7 4区医学 Q2 PERIPHERAL VASCULAR DISEASE

Microvascular research Pub Date : 2025-09-18 DOI:10.1016/j.mvr.2025.104876

Yuma Tega , Fuki Kusakabe , Shin-ichi Akanuma , Ken-ichi Hosoya

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引用次数: 0

Abstract

Purpose

Taurine exists abundantly in the retina and plays a vital role in retinal function. Monocarboxylate transporter 7 (MCT7) is found as a facilitative taurine transporter; however, its involvement in taurine dynamics in the retina is not yet fully understood. The purpose of the present study is to clarify the protein expression and function of MCT7 in retinal cells.

Methods

Guinea pig antibodies were raised against the amino acid residues of rat MCT7, and immunostaining was performed to clarify protein expression in the rat retina. To characterize taurine influx into retinal pericytes, a [³H]taurine transport assay was conducted using TR-rPCT1 cells, immortalized rat retinal pericytes. A knockdown assay using MCT7 small interfering RNA (siRNA) was performed to examine the involvement of MCT7 in taurine efflux in TR-rPCT1 and immortalized rat retinal capillary endothelial (TR-iBRB2) cells.

Results

The MCT7 protein expression was observed throughout the retinal layer. Immunostaining of isolated retinal capillaries revealed MCT7 expression in retinal pericytes and capillary endothelial cells. [³H]Taurine influx transport in TR-rPCT1 cells depends on temperature, concentration (K_m = 11.2 μM), and extracellular Na⁺ and Cl⁻, and was inhibited by substrates for taurine transporter (TauT), suggesting the involvement of TauT in taurine influx in retinal pericytes. Moreover, MCT7 siRNA decreased MCT7 expression and [³H]taurine efflux in TR-rPCT1 and TR-iBRB2 cells, suggesting that the taurine efflux transport involves MCT7 at least partly.

Conclusions

The present study revealed that MCT7 functions as a taurine efflux transporter in both retinal pericytes and capillary endothelial cells.

查看原文本刊更多论文

单羧酸转运蛋白7参与大鼠视网膜周细胞和毛细血管内皮细胞的牛磺酸外排运输。

目的：牛磺酸在视网膜中大量存在，对视网膜功能起着至关重要的作用。单羧酸转运蛋白7 （MCT7）是一种促进性牛磺酸转运蛋白；然而，它对视网膜中牛磺酸动力学的参与尚未完全了解。本研究的目的是阐明MCT7在视网膜细胞中的蛋白表达和功能。方法：培养针对大鼠MCT7氨基酸残基的豚鼠抗体，并进行免疫染色以澄清大鼠视网膜中的蛋白表达。为了描述牛磺酸向视网膜周细胞内流的特征，使用TR-rPCT1细胞（永生化大鼠视网膜周细胞）进行了[3H]牛磺酸运输试验。使用MCT7小干扰RNA （siRNA）进行敲低实验，以检测MCT7在TR-rPCT1和永生化大鼠视网膜毛细血管内皮细胞（TR-iBRB2）中牛磺酸外排的参与。结果：MCT7蛋白在视网膜全层均有表达。分离的视网膜毛细血管免疫染色显示MCT7在视网膜周细胞和毛细血管内皮细胞中表达。[3H] TR-rPCT1细胞的牛磺酸内流转运受温度、浓度（Km = 11.2 μM）和细胞外Na+和Cl-的影响，并被牛磺酸转运蛋白（taaut）底物抑制，提示taaut参与了视网膜周细胞的牛磺酸内流。此外，MCT7 siRNA降低了TR-rPCT1和TR-iBRB2细胞中MCT7的表达和[3H]牛磺酸外排，表明牛磺酸外排运输至少部分涉及MCT7。结论：本研究表明MCT7在视网膜周细胞和毛细血管内皮细胞中均作为牛磺酸外排转运体起作用。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Microvascular research 医学-外周血管病

CiteScore

6.00

自引率

3.20%

发文量

158

审稿时长

43 days

期刊介绍： Microvascular Research is dedicated to the dissemination of fundamental information related to the microvascular field. Full-length articles presenting the results of original research and brief communications are featured. Research Areas include: • Angiogenesis • Biochemistry • Bioengineering • Biomathematics • Biophysics • Cancer • Circulatory homeostasis • Comparative physiology • Drug delivery • Neuropharmacology • Microvascular pathology • Rheology • Tissue Engineering.