Multiple pathways for cationic amino acid transport in rat seminiferous tubule cells
Multiple pathways for cationic amino acid transport in rat seminiferous tubule cells
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DOI：
10.1095/biolreprod.106.056168
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发表时间：
2007-02-01
影响因子：
3.6
通讯作者：
Bauche, Francoise
中科院分区：
文献类型：
--
作者：
Cerec, Virginie;Piquet-Pellorce, Claire;Bauche, Francoise
精氨酸和鸟氨酸在睾丸的各种生物过程中都很重要，但细胞外阳离子氨基酸向精小管细胞的传递仍然知之甚少。我们研究了阳离子氨基酸转运蛋白在离体大鼠支持细胞、小管周围细胞、粗线精母细胞和早期精子细胞中的活性和表达。我们评估了l -精氨酸摄取动力学、转运对Na+的依赖性、阳离子和中性氨基酸对摄取的顺式抑制谱以及阳离子氨基酸转运体对反式刺激的敏感性，并通过RT-PCR研究了编码它们的基因的表达。我们的数据表明，L-精氨酸主要通过系统y(+)L （SLC3A2/SLC7A6）和系统y(+) （SLC7A1和SLC7A2）被支持细胞和小管周围细胞吸收，系统B0+也有少量贡献。相比之下，系统B0+与系统y(+)L （SLC3A2/SLC7A7和SLC7A6）相关，在粗线精母细胞和早期精母细胞中对阳离子氨基酸的运输做出了重要贡献。支持细胞的l -精氨酸转运率高于其他精小管细胞。Sertoli细胞中精氨酸运输的高效率以及在这些细胞中占主导地位的y(+)L系统的特性强烈表明，Sertoli细胞在向生殖细胞提供L-精氨酸和其他阳离子氨基酸方面发挥了关键作用。此外，虽然细胞因子诱导小管周围细胞和支持细胞产生一氧化氮（NO），但在这些细胞中观察到细胞因子很少或没有上调精氨酸运输。因此，NO的合成不依赖于这些体小管细胞中精氨酸运输的刺激。
Arginine and ornithine are known to be important for various biological processes in the testis, but the delivery of extracellular cationic amino acids to the seminiferous tubule cells remains poorly understood. We investigated the activity and expression of cationic amino acid transporters in isolated rat Sertoli cells, peritubular cells, pachytene spermatocytes, and early spermatids. We assessed the L-arginine uptake kinetics, Na+ dependence of transport, profiles of cis inhibition of uptake by cationic and neutral amino acids, and sensitivity to trans stimulation of cationic amino acid transporters, and studied the expression of the genes encoding them by RT-PCR. Our data suggest that L-arginine is taken up by Sertoli cells and peritubular cells, principally via system y(+)L (SLC3A2/SLC7A6) and system y(+) (SLC7A1 and SLC7A2), with system B0+ making a minor contribution. By contrast, system B0+, associated with system y(+)L (SLC3A2/SLC7A7 and SLC7A6), made a major contribution to the transport of cationic amino acids in pachytene spermatocytes and early spermatids. Sertoli cells had higher rates Of L-arginine transport than the other seminiferous tubule cells. This high efficiency of arginine transport in Sertoli cells and the properties of the y(+)L system predominating in these cells strongly suggest that Sertoli cells play a key role in supplying germ cells with L-arginine and other cationic amino acids. Furthermore, whereas cytokines induce nitric oxide (NO) production in peritubular and Sertoli cells, little or no upregulation of arginine transport by cytokines was observed in these cells. Thus, NO synthesis does not depend on the stimulation of arginine transport in these somatic tubular cells.