外周血单核细胞增殖增加核黄素内流。

J Zempleni, D M Mock
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引用次数: 0

摘要

先前我们证明了外周血单核细胞(PBMC)的增殖导致细胞对生物素的摄取增加五倍;这种增加是由PBMC表面生物素转运体数量的增加所介导的。在本研究中,我们通过确定细胞对核黄素的摄取是否也在增殖的PBMC中增加,以及这种增加是否也是由每个细胞中转运蛋白数量的增加所介导的,来研究这种现象的特异性。我们研究了静止和增殖的PBMC中[3H]核黄素的摄取。在静止PBMC中,[3H]核黄素摄取表现出饱和动力学,并通过添加未标记的核黄素(P < 0.05)或光色(P < 0.01)而减少。这些观察结果与转运蛋白介导的摄取一致。[3H]与37℃(P < 0.01)和2,4 -二硝基苯酚(P < 0.05)相比,4℃时核黄素的摄取减少,但瓦巴因和无钠培养基中孵育没有减少。这些数据为一种依赖能量但不依赖钠的转运体提供了证据。增殖PBMC的[3H]核黄素积累量约为静止PBMC的4倍(P < 0.05)。由于在静止和增殖的PBMC中,转运蛋白亲和力和每个细胞的转运蛋白数量(根据最大转运率来判断)是相似的,我们假设增殖的PBMC对核黄素摄取的增加仅仅反映了细胞体积的增加。为了验证这一假设,使用高渗透压介质减少PBMC体积;[3H]核黄素摄取降至等渗对照组的50%左右(P < 0.01)。因此,我们认为增殖的PBMC通过两种不同的机制增加了细胞中核黄素和生物素的含量。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Proliferation of peripheral blood mononuclear cells increases riboflavin influx.

Previously we demonstrated that proliferation of peripheral blood mononuclear cells (PBMC) causes a five-fold increase in cellular uptake of biotin; this increase is mediated by an increased number of biotin transporters on the PBMC surface. In the present study, we investigated the specificity of this phenomenon by determining whether the cellular uptake of riboflavin also increases in proliferating PBMC and whether the increase is also mediated by an increased number of transporters per cell. We characterized [3H]riboflavin uptake in both quiescent and proliferating PBMC. In quiescent PBMC, [3H]riboflavin uptake exhibited saturation kinetics and was reduced by addition of unlabeled riboflavin (P < 0.05) or lumichrome (P < 0.01). These observations are consistent with transporter-mediated uptake. [3H]Riboflavin uptake was reduced at 4 degrees C compared with 37 degrees C (P < 0.01) and by 2, 4-dinitrophenol (P < 0.05) but not by ouabain or incubation in sodium-free medium. These data provide evidence for an energy-dependent but sodium-independent transporter. Proliferating PBMC accumulated approximately four times more [3H]riboflavin than quiescent PBMC (P < 0.05). Because both transporter affinity and transporter number per cell (as judged by maximal transport rate) were similar in quiescent and proliferating PBMC, we hypothesize that the increased riboflavin uptake by proliferating PBMC reflects only increased cellular volume. To test this hypothesis, PBMC volume was reduced using hyperosmolar medium; [3H]riboflavin uptake decreased to about 50% of isotonic controls (P < 0.01). Thus we conclude that proliferating PBMC increase cellular content of riboflavin and biotin by two different mechanisms.

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