Alpha-aminoisobutyric acid transport in human leukemic lymphocytes: in vitro characteristics and inhibition by cortisol and cycloheximide.
Alpha-aminoisobutyric acid transport in human leukemic lymphocytes: in vitro characteristics and inhibition by cortisol and cycloheximide.
复制标题
人白血病淋巴细胞中的α-氨基异丁酸转运：体外特征以及皮质醇和放线菌酮的抑制。
DOI：
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发表时间：
1972
影响因子：
15.9
通讯作者：
W. Peck
中科院分区：
文献类型：
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作者：
D. Baran;M. Lichtman;W. Peck
我们研究了α-氨基异丁酸(AIB)-3-(14)C在未经治疗的慢性淋巴细胞白血病患者外周血淋巴细胞中的转运及其对皮质醇和放线菌酮的反应。AIB-3-(14)C在60min内呈线性增加，120min时达到一个明显的稳定状态。在16个不同患者的细胞中，AIB的初始蓄积速率(V(O))在1.1~10.2摩尔/kg细胞H(2O)/min之间变化，但在重复研究1-9个月以上的6个患者中，有5个患者的细胞可重现V(O)，且V(O)与淋巴细胞计数呈正相关(r=0.51，P=0.01)。用放线菌酮几乎完全抑制蛋白质合成可以减少AIB在4例AIB转运速率较高的患者细胞中的积聚，但对4例AIB积累较慢的患者细胞中的AIB转运没有影响。这些结果表明，主动转运在一定程度上依赖于不稳定蛋白的存在，其周转率在不同的细胞群体中是不同的。经10微米皮质醇处理240分钟后，16例患者细胞中AIB-3-(14)C的初始积累率(V(O))降低了43.4+/-4.1%(SE)(范围为9-66%)。在9个月的时间里，5名患者中有4名患者的抑制程度没有明显变化。皮质醇的作用与其起始浓度成正比，并在低浓度(0.1-1.0微米)下发展。皮质醇似乎通过抑制主动摄取来减少AIB的蓄积，因为它既没有促进AIB的外流，也没有抑制明显的非饱和转运。皮质醇通过从头合成蛋白质的过程间接地抑制AIB的转运，因为(A)在处理60min后才出现抑制，(B)在随后在无皮质醇的培养液中孵育60min的处理细胞中出现，(C)即使放线菌酮本身没有减少AIB的转运，但在与放线菌酮同时阻断蛋白质合成的过程中，皮质醇未能发展。
We have studied the transport of alpha-aminoisobutyric acid (AIB)-3-(14)C and its response to cortisol and cycloheximide in vitro in blood lymphocytes from untreated patients with chronic lymphocytic leukemia. The accumulation of AIB-3-(14)C increased in a linear fashion for 60 min, and reached an apparent steady state in 120 min. The initial rate of AIB accumulation (V(o)) varied from 1.1 to 10.2 mumoles/kg cell H(2)O per min in cells from 16 different patients; however, V(o) was reproducible in cells from five of six patients which were studied repeatedly over 1-9 months, and correlated positively with the lymphocyte count (r = 0.51, P = < 0.01). Virtually total inhibition of protein synthesis with cycloheximide was found to decrease the accumulation of AIB in cells from four patients which had high rates of AIB transport, but had no effect on transport in cells from four patients which accumulated AIB more slowly. These results indicate that active transport depends, in part, upon the presence of labile protein with a turnover rate which varies among different cell populations. Treatment with 10 muM cortisol for 240 min in vitro reduced the initial rate of AIB-3-(14)C accumulation (V(o)) by 43.4+/-4.1% (SE) (range, 9-66%) in cells from 16 patients. The degree of inhibition did not vary appreciably over a 9 month period in four of five patients. The effect of cortisol was proportional to its starting concentration, and developed at low concentrations (0.1-1.0 muM). Cortisol appears to decrease AIB accumulation by inhibiting active uptake, since it neither enhanced the exodus of AIB, nor inhibited apparently nonsaturable transport. Inhibition was noncompetitive in type, suggesting that cortisol decreases the total capacity of the active transport mechanism.Cortisol inhibited AIB transport indirectly by a process which involved de novo protein synthesis, since inhibition (a) appeared only after 60 min of treatment, (b) was present in treated cells which were subsequently incubated for 60 min in cortisol-free medium, and (c) failed to develop during simultaneous blockade of protein synthesis with cycloheximide, even when cycloheximide itself did not decrease AIB transport.