Cooper C L, Berrier A L, Roman C, Calame K L
Department of Microbiology, College of Physician and Surgeons, Columbia University, New York, NY 10032.
J Immunol. 1994 Dec 1;153(11):5049-58.
The importance of C/EBP proteins in B cell biology is suggested by the occurrence of functionally important C/EBP binding sites in Ig gene enhancers and promoters, and the knowledge that family member NF-IL-6 is induced in other systems in response to regulators of B cell differentiation. We have studied the expression pattern and activity of C/EBP family transcriptional regulators in B cells at different developmental stages by using B cell lines and normal splenic B cells. Two family members, Ig/EBP and NF-IL-6, seem to be the major regulators of C/EBP site-dependent transcriptional activity in B cells. Negative regulator Ig/EBP is predominantly present in early B cells; activator NF-IL-6 increases in more mature B cells and is induced by LPS activation of splenic B cells. LIP, an N-terminally truncated form of NF-IL-6, was found in most B cell lines tested; LIP can act as a weak transcriptional activator in B cell lines. Partly as a result of the differential amounts of C/EBP family proteins, C/EBP sites do not function as activator sites in early B cells but are activator sites in terminally differentiated B cells.
Ig基因增强子和启动子中存在功能重要的C/EBP结合位点，以及已知家族成员NF-IL-6在其他系统中会因B细胞分化调节因子而被诱导，这些都表明C/EBP蛋白在B细胞生物学中具有重要性。我们通过使用B细胞系和正常脾B细胞，研究了不同发育阶段B细胞中C/EBP家族转录调节因子的表达模式和活性。两个家族成员，即Ig/EBP和NF-IL-6，似乎是B细胞中C/EBP位点依赖性转录活性的主要调节因子。负调节因子Ig/EBP主要存在于早期B细胞中；激活因子NF-IL-6在更成熟的B细胞中增加，并由脾B细胞的LPS激活诱导产生。在大多数测试的B细胞系中发现了NF-IL-6的N端截短形式LIP；LIP在B细胞系中可作为弱转录激活因子。部分由于C/EBP家族蛋白量的差异，C/EBP位点在早期B细胞中不作为激活位点起作用，但在终末分化的B细胞中是激活位点。
