Calcium-calmodulin signaling induced by epithelial cell differentiation upregulates BRAK/CXCL14 expression via the binding of SP1 to the BRAK promoter region
Calcium-calmodulin signaling induced by epithelial cell differentiation upregulates BRAK/CXCL14 expression via the binding of SP1 to the BRAK promoter region
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DOI：
10.1016/j.bbrc.2012.01.157
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发表时间：
2012-04-06
影响因子：
3.1
通讯作者：
Kubota, Eiro
中科院分区：
文献类型：
--
作者：
Ikoma, Takeharu;Ozawa, Shigeyuki;Kubota, Eiro
趋化因子BRAK/CXCL 14（BRAK）在正常鳞状上皮中表达，但在头颈部鳞状细胞癌中不表达或以可忽略的水平表达。已知恶性细胞与正常上皮细胞相比是去分化的，这表明分化线索在BRAK表达中的作用。因此，我们研究了上皮细胞中BRAK表达和分化水平阶段之间的关系。免疫组化结果显示，BRAK蛋白表达于正常上皮棘细胞层以上的细胞。在培养的HSC-3细胞中，BRAK mRNA的表达通过细胞接触以细胞密度依赖性方式显著上调，并且细胞分化标记物如外皮蛋白、半胱氨酸蛋白酶抑制剂-A、TGM 1、TGM 3和TGM 5的mRNA表达伴随增加。此外，由细胞接触诱导的BRAK上调被氯丙嗪抑制，氯丙嗪是一种特异性钙调蛋白抑制剂。我们以前报道过GC盒和BRAK启动子区的TATA样序列与BRAK的表达相关。使用启动子测定和ChIP，我们证明了刺激蛋白-1（SP1）转录因子与BRAKE转录起始位点上游的GC盒的结合对于BRAKE的细胞密度依赖性上调是必要的。这些结果表明，上调的BRAK是伴随着由钙/钙调素信号诱导的上皮细胞的分化，和SP1结合到BRAM启动子区在这个信号中发挥了重要作用。(C)2012 Elsevier Inc. All rights reserved.
The chemokine BRAK/CXCL14 (BRAK) is expressed in normal squamous epithelium, but is not expressed or is expressed at negligible levels in head and neck squamous cell carcinoma. Malignant cells are known to be dedifferentiated compared with normal epithelial cells, suggesting a role for differentiation cues in the expression of BRAK. Thus, we examined the relationship between BRAK expression and stages of differentiation level in epithelial cells. Immunohistochemical analysis showed that BRAK protein was expressed in cells above the spinous cell layer in normal epithelia. In HSC-3 cells in culture, expression of BRAK mRNA was significantly upregulated by cell contact in a cell density-dependent manner, and mRNA expression of cell differentiation markers such as involucrin, cystatin-A, TGM1, TGM3, and TGM5 was concomitantly augmented. Furthermore, the upregulation of BRAK induced by cell contact was suppressed by chlorpromazine, a specific inhibitor of calmodulin. We previously reported that GC boxes and a TATA-like sequence in the BRAK promoter region are associated with the expression of BRAK. Using a promoter assay and ChIP, we demonstrated that binding of the stimulating protein-1 (SP1) transcription factor to a GC box upstream of the BRAK transcription start site was necessary for cell density-dependent upregulation of BRAK. These results indicated that upregulation of BRAK was accompanied by differentiation of epithelial cells induced by calcium/calmodulin signaling, and that SP1 binding to the BRAM promoter region played an important role in this signaling. (C) 2012 Elsevier Inc. All rights reserved.