Gilmore-Hebert M, Schneider J W, Greene A L, Berliner N, Stolle C A, Lomax K, Mercer R W, Benz E J
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.
J Clin Invest. 1989 Jul;84(1):347-51. doi: 10.1172/JCI114161.
Multiple isoenzymes of the Na+,K+-ATPase (alpha, alpha+, and alpha 3) have been identified by molecular cloning (Shull, G. E., J. Greeb, and J. B. Lingrel. 1986. Biochemistry. 25:8125-8132; and Schneider, J. W., R. W. Mercer, and E. J. Benz, Jr. 1987. Clin. Res. 35:585A. [Abstr.]). At least one of these, the alpha 3 chain, represents a novel form for which protein products and enzymatic activities are just beginning to be defined in rodents. We have recently demonstrated that expression of alpha 3 is largely confined to neuromuscular tissues of fetal and adult rats (Schneider, J. W., R. W. Mercer, M. Gilmore-Hebert, M. F. Utset, C. Lai, A. Greene, and E. J. Benz, Jr. 1988. Proc. Natl. Acad. Sci. USA. 85:284-288). We now report that certain human leukemia cell lines including HL60, HEL, and Molt 4 express mRNA for both alpha and alpha 3 isoforms of Na+,K+-ATPase; mRNA was not detected in several other cell lines, including K562 and U937; no cell lines expressed alpha+ mRNA. In uninduced HL60 cells, alpha 3 mRNA comprised 20-30% of total Na+,K+-ATPase mRNA. Furthermore, in HL60 and HEL cells, both alpha and alpha 3 mRNA declined after induction of maturation by DMSO, retinoic acid, or hemin. However, the reduction in alpha 3 mRNA was far more dramatic. alpha 3 mRNA virtually disappeared, but alpha mRNA declined by only approximately 50%. In contrast, when maturation of HL60 cells along the monocyte/macrophage lineage was induced by exposure to phorbol esters, alpha 3 mRNA remained abundant. Moreover, mRNA for the beta subunit of the Na+,K+-ATPase increased dramatically. Our results demonstrate that the alpha 3 isoform, formerly thought to be confined to neuromuscular tissues, is expressed in restricted lineages of hematopoietic origin. These leukemia cell lines should provide a useful model for analyzing regulation of the alpha 3 isoform gene and characterization of alpha 3 isoform activities.
通过分子克隆已鉴定出钠钾ATP酶的多种同工酶（α、α+和α3）（Shull, G. E., J. Greeb, and J. B. Lingrel. 1986. Biochemistry. 25:8125 - 8132; 以及Schneider, J. W., R. W. Mercer, and E. J. Benz, Jr. 1987. Clin. Res. 35:585A. [摘要]）。其中至少一种，即α3链，代表一种新的形式，其蛋白质产物和酶活性在啮齿动物中才刚刚开始被界定。我们最近证明，α3的表达主要局限于胎儿和成年大鼠的神经肌肉组织（Schneider, J. W., R. W. Mercer, M. Gilmore - Hebert, M. F. Utset, C. Lai, A. Greene, and E. J. Benz, Jr. 1988. Proc. Natl. Acad. Sci. USA. 85:284 - 288）。我们现在报告，某些人类白血病细胞系，包括HL60、HEL和Molt 4，表达钠钾ATP酶α和α3同工型的mRNA；在其他几种细胞系，包括K562和U937中未检测到mRNA；没有细胞系表达α+ mRNA。在未诱导的HL60细胞中，α3 mRNA占钠钾ATP酶总mRNA的20% - 30%。此外，在HL60和HEL细胞中，用二甲基亚砜、视黄酸或血红素诱导成熟后，α和α3 mRNA均下降。然而，α3 mRNA的减少更为显著。α3 mRNA几乎消失，但α mRNA仅下降约50%。相反，当通过暴露于佛波酯诱导HL60细胞沿单核细胞/巨噬细胞谱系成熟时，α3 mRNA仍然丰富。此外，钠钾ATP酶β亚基的mRNA显著增加。我们的结果表明，以前认为局限于神经肌肉组织的α3同工型在造血来源的特定谱系中表达。这些白血病细胞系应该为分析α3同工型基因的调控和α3同工型活性的表征提供一个有用的模型。
