Two components of a secreted cell number-counting factor bind to cells and have opposing effects on cAMP signal transduction in Dictyostelium
Two components of a secreted cell number-counting factor bind to cells and have opposing effects on cAMP signal transduction in Dictyostelium
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DOI：
10.1074/jbc.m309101200
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发表时间：
2003-12-26
影响因子：
4.8
通讯作者：
Gomer, RH
中科院分区：
文献类型：
--
作者：
Brock, DA;Ehrenman, K;Gomer, RH
一种被称为计数因子（CF）的分泌的450 kDa蛋白质复合物是负反馈回路的一部分，该负反馈回路调节由发育中的网骨藻细胞形成的群体的大小。CF的两个组分是计数和CF 50。重组countin和重组CF 50均减少网骨藻中的群大小。countin（-）细胞具有降低的cAMP刺激的cAMP脉冲，而重组countin增强cAMP脉冲。我们发现，cf 50（-）细胞有一个增加的cAMP脉冲，而重组CF 50降低cAMP脉冲，表明计数和CF 50有相反的作用cAMP信号转导。此外，countin和CF 50对cAMP刺激的Erk 2活化具有相反的作用。然而，与重组计数素一样，重组CF 50增加细胞运动性。我们以前发现细胞结合重组计数蛋白的Hill系数接近2，K-H为60 pM，并且接近53个位点/细胞。我们发现细胞也结合I-125-重组CF 50，希尔系数接近2，K-H接近15 ng/ml（490 pM），并且接近56个位点/细胞。Countin和CF 50需要彼此的存在才能影响群体大小，但Countin的存在不是CF 50与细胞结合所必需的，CF 50也不是Countin与细胞结合所必需的。我们的工作假设是，由countin结合细胞激活的信号转导途径调节由CF 50结合细胞激活的信号转导途径，反之亦然，这两种途径可以通过它们对cAMP信号转导的影响来区分。
A secreted 450-kDa complex of proteins called counting factor (CF) is part of a negative feedback loop that regulates the size of the groups formed by developing Dictyostelium cells. Two components of CF are countin and CF50. Both recombinant countin and recombinant CF50 decrease group size in Dictyostelium. countin(-) cells have a decreased cAMP-stimulated cAMP pulse, whereas recombinant countin potentiates the cAMP pulse. We find that cf50(-) cells have an increased cAMP pulse, whereas recombinant CF50 decreases the cAMP pulse, suggesting that countin and CF50 have opposite effects on cAMP signal transduction. In addition, countin and CF50 have opposite effects on cAMP-stimulated Erk2 activation. However, like recombinant countin, recombinant CF50 increases cell motility. We previously found that cells bind recombinant countin with a Hill coefficient of similar to2, a K-H of 60 pM, and similar to53 sites/cell. We find here that cells also bind I-125-recombinant CF50, with a Hill coefficient of similar to2, a K-H of similar to15 ng/ml (490 pM), and similar to56 sites/cell. Countin and CF50 require each other's presence to affect group size, but the presence of countin is not necessary for CF50 to bind to cells, and CF50 is not necessary for countin to bind to cells. Our working hypothesis is that a signal transduction pathway activated by countin binding to cells modulates a signal transduction pathway activated by CF50 binding to cells and vice versa and that these two pathways can be distinguished by their effects on cAMP signal transduction.