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C-terminal fragment signaling of membrane-anchored growth factor HB-EGF

膜锚定生长因子 HB-EGF 的 C 端片段信号传导

基本信息

批准号：
15390097
负责人：
HIGASHIYAMA Shigeki
金额：
$ 9.92万
依托单位：
Ehime University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15390097/
关键词：
HB-EGF Shedding Transcriptional repressor PLZF EGF family metalloprotease gene regulation shedding repressor

项目摘要

Heparin-binding EGF-like growth factor(HB-EGF) is initially synthesized as a type I transmembrane protein (proHB-EGF). The proHB-EGF is shed by specific metalloproteases, releasing the N-terminal fragment into the extracellular space as a soluble growth factor (HB-EGF) and the C-terminal fragment (HB-EGF-C) into the intracellular space, where it prevents transcriptional repression by the promyelocytic leukemia zinc finger protein (PLZF). The goal of the present study was to characterize regulation of proHB-EGF shedding and study its temporal variations in HB-EGF-C localization throughout the cell cycle. Quantitative combination analyses of cell surface proHB-EGF and HB-EGF in conditioned medium showed that proHB-EGF shedding occurred during the G1 cell cycle phase. Laser scanning cytometry revealed that HB-EGF-C was internalized into the cytoplasm during the late G1 phase and accumulated in the nucleus beginning in the S phase. Subsequent nuclear export of PLZF occurred during the late S phase. Further, HB-EGF-C was localized around the centrosome following breakdown of the nuclear envelope and was localized to the interzonal space with chromosome segregation in the late M phase. Temporal variations in HB-EGF localization throughout the cell cycle were also characterized by time-lapse imaging of cells expressing YFP-tagged proHB-EGF, and these results were consistent with those obtained in cytometry studies. Furthermore, we identified BCL-6 and BAZF as transcriptional repressors targeted by HB-EGF-C. These results indicate that proHB-EGF shedding and subsequent HB-EGF-C signaling are related with progression of the cell cycle and may provide a clue to understand the unique biological significance of non-receptor-mediated signaling of proHB-EGF in cell growth.

肝素结合egf样生长因子（HB-EGF）最初是作为I型跨膜蛋白（proHB-EGF）合成的。proHB-EGF通过特定的金属蛋白酶脱落，将n端片段作为可溶性生长因子（HB-EGF）释放到细胞外空间，将c端片段（HB-EGF- c）释放到细胞内空间，在那里它阻止早幼粒细胞白血病锌指蛋白（PLZF）的转录抑制。本研究的目的是表征proHB-EGF脱落的调节，并研究其在整个细胞周期中HB-EGF-C定位的时间变化。在条件培养基中对细胞表面的proHB-EGF和HB-EGF进行定量联合分析，结果表明，proHB-EGF在细胞G1周期发生脱落。激光扫描细胞术显示HB-EGF-C在G1期晚期被内化到细胞质中，并在S期开始在细胞核中积累。PLZF的后续核出口发生在S阶段后期。此外，HB-EGF-C在核膜破裂后定位于中心体周围，并在M期后期定位于染色体分离的带间空间。通过对表达yfp标记的proHB-EGF的细胞进行延时成像，我们也发现了HB-EGF在整个细胞周期中定位的时间变化，这些结果与细胞术研究结果一致。此外，我们发现BCL-6和BAZF是HB-EGF-C靶向的转录抑制因子。这些结果表明，proHB-EGF的脱落和随后的HB-EGF-C信号传导与细胞周期的进展有关，并可能为理解非受体介导的proHB-EGF信号传导在细胞生长中的独特生物学意义提供线索。