Haerry T E, Khalsa O, O'Connor M B, Wharton K A
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
Development. 1998 Oct;125(20):3977-87. doi: 10.1242/dev.125.20.3977.
In Drosophila wing discs, a morphogen gradient of DPP has been proposed to determine the transcriptional response thresholds of the downstream genes sal and omb. We present evidence that the concentration of the type I receptor TKV must be low to allow long-range DPP diffusion. Low TKV receptor concentrations result, however, in low signaling activity. To enhance signaling at low DPP concentrations, we find that a second ligand, GBB, augments DPP/TKV activity. GBB signals primarily through the type I receptor SAX, which synergistically enhances TKV signaling and is required for proper OMB expression. We show that OMB expression in wing discs requires synergistic signaling by multiple ligands and receptors to overcome the limitations imposed on DPP morphogen function by receptor concentration levels.
在果蝇翅芽中，有人提出DPP的形态发生素梯度可确定下游基因sal和omb的转录反应阈值。我们提供的证据表明，I型受体TKV的浓度必须较低才能使DPP进行长距离扩散。然而，低浓度的TKV受体会导致信号传导活性较低。为了在低DPP浓度下增强信号传导，我们发现第二种配体GBB可增强DPP/TKV活性。GBB主要通过I型受体SAX发出信号，SAX可协同增强TKV信号传导，并且是omb正常表达所必需的。我们表明，翅芽中omb的表达需要多种配体和受体的协同信号传导，以克服受体浓度水平对DPP形态发生素功能造成的限制。
