INCREASE IN RECEPTOR-LIKE PROTEIN-TYROSINE-PHOSPHATASE ACTIVITY AND EXPRESSION LEVEL ON DENSITY-DEPENDENT GROWTH ARREST OF ENDOTHELIAL-CELLS
INCREASE IN RECEPTOR-LIKE PROTEIN-TYROSINE-PHOSPHATASE ACTIVITY AND EXPRESSION LEVEL ON DENSITY-DEPENDENT GROWTH ARREST OF ENDOTHELIAL-CELLS
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DOI：
10.1042/bj3110097
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发表时间：
1995-10-01
影响因子：
4.1
通讯作者：
CHAP, H
中科院分区：
文献类型：
--
作者：
GAITS, F;LI, RY;CHAP, H
在两种细胞系中检测了蛋白酪氨酸磷酸酶（PTO 2）活性：人脐静脉内皮（HUVE）细胞，其显示细胞生长的接触抑制，和A427人腺癌细胞，其已经失去了这种能力。以高密度收获的HUVE细胞显示膜相关PTK活性增加10倍。A427细胞则无此现象。此外，通过刺激剂如碱性成纤维细胞生长因子或通过阻断化合物如胸苷或苏拉明修饰HUVE细胞生长速率导致PTK活性无变化，表明在融合时观察到的膜相关活性增加是细胞-细胞接触定向生长停滞的特异性。在HUVE和A427细胞中检测了各种PTOmRNA的表达。在所测试的受体样PTPases中，两种仅在HUVE细胞中表达（PTP γ和HPTP β）。只有HPTP β，这是在其细胞外区域的免疫球蛋白超家族的细胞粘附受体的结构相似，展示了一种模式的表达相关的PTTP活性的增加。竞争性PCR用于定量其在细胞培养期间的表达。检测到HPTP β mRNA表达增加12倍，并且与PTTP活性的时间过程平行。这一观察结果强烈暗示受体样PTPases在密度依赖性生长停滞。
Protein tyrosine phosphatase (PTPase) activity was examined in two cell lines: human umbilical vein endothelial (HUVE) cells, which display contact inhibition of cell growth, and A427 human adenocarcinoma cells, which have lost this ability. HUVE cells harvested at high density displayed a 10-fold increase in membrane-associated PTPase activity. A427 cells exhibited no such phenomenon. Moreover, modification of HUVE cell growth rate by a stimulating agent such as basic fibroblast growth factor or by blocking compounds such as thymidine or suramin resulted in no change in PTPase activity, suggesting that the observed increase in membrane-associated activity at confluency was specific for cell-cell-contact-directed growth arrest. The expression of various PTPase mRNAs was examined in HUVE and A427 cells. Of the receptor-like PTPases tested, two were exclusively expressed in HUVE cells (PTP gamma and HPTP beta). Only HPTP beta, which is structurally similar in its extracellular region to cell-adhesion receptors of the immunoglobulin superfamily, displayed a pattern of expression related to the increase in PTPase activity. Competitive PCR was used to quantify its expression during cell culture. A 12-fold increase in HPTP beta mRNA expression was detected and it parallelled the time course of PTPase activity. This observation strongly implicates receptorlike PTPases in density-dependent growth arrest.