Le Roux I, Joliot A H, Bloch-Gallego E, Prochiantz A, Volovitch M
Centre National de la Recherche Scientifique Unité Recherche Associée 1414, Ecole Normale Supérieure, Paris, France.
Proc Natl Acad Sci U S A. 1993 Oct 1;90(19):9120-4. doi: 10.1073/pnas.90.19.9120.
In previous reports we have demonstrated that the 60-aa peptide corresponding to the homeodomain of the Drosophila protein Antennapedia (pAntp) translocates through the membrane of neurons in culture, accumulates in neuronal nuclei, and promotes neurite growth. To analyze the importance of specific pAntp DNA-binding properties in this phenomenon we have constructed three mutant versions of pAntp that differ in their ability to translocate through the membrane and to bind specifically the cognate sequence for homeodomains present in the promoter of HoxA5. We demonstrate that removing two hydrophobic residues of the third helix inhibits pAntp internalization and suppresses its neurotrophic activity. We also show that pAntp neurotrophic activity is lost when mutations are introduced in positions preserving its penetration and nuclear accumulation but abolishing its capacity to bind specifically the cognate DNA-binding motif for homeoproteins. Our results strongly suggest that pAntp neurotrophicity requires both its internalization and its specific binding to homeobox cognate sequences. We propose that homeoproteins might regulate important events in the morphological differentiation of the postmitotic neuron.
在先前的报告中，我们已经证明，与果蝇蛋白触角足蛋白（pAntp）的同源结构域相对应的60个氨基酸的肽可穿过培养的神经元膜，积聚在神经元细胞核中，并促进神经突生长。为了分析特定pAntp DNA结合特性在此现象中的重要性，我们构建了三个pAntp突变体版本，它们在穿过膜的能力以及特异性结合HoxA5启动子中存在的同源结构域的同源序列方面存在差异。我们证明，去除第三个螺旋的两个疏水残基会抑制pAntp的内化并抑制其神经营养活性。我们还表明，当在保留其穿透和核积累但消除其特异性结合同源蛋白的同源DNA结合基序能力的位置引入突变时，pAntp的神经营养活性丧失。我们的结果强烈表明，pAntp的神经营养性需要其内化以及与同源框同源序列的特异性结合。我们提出，同源蛋白可能调节有丝分裂后神经元形态分化中的重要事件。
