Yokota S, Yuan D, Katagiri T, Eisenberg R A, Cohen P L, Ting J P
Lineberger Cancer Research Center, University of North Carolina, Chapel Hill 27514.
J Immunol. 1987 Oct 15;139(8):2810-7.
Mice homozygous for the lpr gene spontaneously develop massive lymphoproliferation and an associated lupus-like autoimmune disease. In addition, the total lymphoid organs from these mice express high levels of mRNA for the c-myb proto-oncogene. Since enhanced c-myb mRNA is normally observed in immature thymic lymphocytes but not normal peripheral T cells, this may be indicative of the abnormal maturation state of lpr T lymphocytes. To determine whether the abnormal Lyt-2-, L3T4- (double negative) T lymphocytes in lpr mice express high c-myb, we purified this population by complement-mediated lysis with anti-L3T4 and Lyt-2 antibody from B6/lpr lymph nodes. We found that increased c-myb mRNA is expressed by this double-negative subset. To assess whether the high level of c-myb correlated with the aberrant undifferentiated state of these cells, we examined the effects of T cell differentiation inducers, phorbol ester and calcium ionophore, on c-myb expression. We found that c-myb levels were depressed after phorbol ester and calcium ionophore treatment. Concomitantly, transcriptional activation of the interleukin 2 receptor gene and progression of these cells through the cell cycle were observed. Thus, in B6/lpr double-negative T cells, the regulation of c-myb, interleukin 2 receptor, and cell proliferation may be interrelated. A combination of Northern hybridization and nuclear run-on transcription assays revealed two levels at which c-myb can be regulated in the double-negative T cell subset. The gene is transcriptionally regulated in untreated cells, but on induction with phorbol ester and calcium ionophore, the gene is negatively regulated via post-transcriptional mechanisms.
纯合 lpr 基因的小鼠会自发出现大量淋巴细胞增殖以及相关的狼疮样自身免疫性疾病。此外，这些小鼠的整个淋巴器官中 c-myb 原癌基因的 mRNA 表达水平很高。由于增强的 c-myb mRNA 通常在未成熟胸腺淋巴细胞中观察到，而不在正常外周 T 细胞中，这可能表明 lpr T 淋巴细胞的成熟状态异常。为了确定 lpr 小鼠中异常的 Lyt-2-、L3T4-（双阴性）T 淋巴细胞是否表达高水平的 c-myb，我们通过用抗 L3T4 和 Lyt-2 抗体从 B6/lpr 淋巴结进行补体介导的裂解来纯化这个细胞群体。我们发现这个双阴性亚群表达增加的 c-myb mRNA。为了评估高水平的 c-myb 是否与这些细胞异常的未分化状态相关，我们研究了 T 细胞分化诱导剂佛波酯和钙离子载体对 c-myb 表达的影响。我们发现佛波酯和钙离子载体处理后 c-myb 水平降低。同时，观察到白细胞介素 2 受体基因的转录激活以及这些细胞通过细胞周期的进程。因此，在 B6/lpr 双阴性 T 细胞中，c-myb、白细胞介素 2 受体和细胞增殖的调节可能是相互关联的。Northern 杂交和细胞核连续转录分析相结合揭示了双阴性 T 细胞亚群中 c-myb 可以在两个水平上受到调节。该基因在未处理的细胞中受到转录调节，但在用佛波酯和钙离子载体诱导后，该基因通过转录后机制受到负调节。
