Catron K M, Purkerson J M, Isakson P C, Bender T P
Department of Microbiology, School of Medicine, University of Virginia, Charlottesville 22908.
J Immunol. 1992 Feb 1;148(3):934-42.
The expression of c-myb mRNA is differentially regulated in murine B lymphoid tumors such that B cell lymphomas and plasmacytomas contain significantly less c-myb mRNA than pre-B cell lymphomas. To examine the low level of c-myb mRNA expression in the murine B cell lymphoma cell line BCL1, nonessential amino acid starvation was used to block these cells in a G1 state. When BCL1 cells were released from this block, a 7- to 10-fold increase in c-myb mRNA was detected in late G1 and S phase cells relative to that detected in exponentially growing BCL1 cells. This increase was not inhibited by aphidicolin. To determine whether cell cycle regulation of c-myb mRNA expression occurred during exponential growth in both murine pre-B cell lymphoma and B cell lymphoma cell lines, elutriation was used to separate exponentially growing cell populations. An increase in c-myb mRNA expression was seen in late G1 and S phase fractions from B cell lymphoma cell lines. In contrast, c-myb mRNA levels remained constant in elutriation fractions isolated from pre-B cell lymphoma cell lines. Expression of c-myb mRNA was not detected in exponentially growing or in Go serum-stimulated murine fibroblasts. These results indicate that constitutive vs cell cycle regulation of c-myb mRNA expression is related to the state of differentiation in murine B lymphoid tumors and suggest that a switch in regulation may occur during normal B cell development.
c-myb mRNA的表达在鼠B淋巴细胞瘤中受到差异调节，使得B细胞淋巴瘤和浆细胞瘤所含的c-myb mRNA明显少于前B细胞淋巴瘤。为了检测鼠B细胞淋巴瘤细胞系BCL1中c-myb mRNA的低水平表达，采用非必需氨基酸饥饿法将这些细胞阻滞于G1期。当BCL1细胞从这种阻滞状态释放时，相对于指数生长的BCL1细胞，在G1晚期和S期细胞中检测到c-myb mRNA增加了7至10倍。这种增加不受阿非迪霉素的抑制。为了确定在鼠前B细胞淋巴瘤和B细胞淋巴瘤细胞系的指数生长过程中是否发生c-myb mRNA表达的细胞周期调控，采用淘洗法分离指数生长的细胞群体。在B细胞淋巴瘤细胞系的G1晚期和S期部分中观察到c-myb mRNA表达增加。相反，从前B细胞淋巴瘤细胞系分离的淘洗部分中c-myb mRNA水平保持恒定。在指数生长的或G0期血清刺激的鼠成纤维细胞中未检测到c-myb mRNA的表达。这些结果表明，c-myb mRNA表达的组成型与细胞周期调控与鼠B淋巴细胞瘤的分化状态有关，并提示在正常B细胞发育过程中可能发生调控的转变。
