Brandenberger R, Kammerer R A, Engel J, Chiquet M
Department of Biophysical Chemistry, Biocenter, University of Basel, Switzerland.
J Cell Biol. 1996 Dec;135(6 Pt 1):1583-92. doi: 10.1083/jcb.135.6.1583.
After denervation of muscle, motor axons reinnervate original synaptic sites. A recombinant fragment of the synapse specific laminin beta 2 chain (s-laminin) was reported to inhibit motor axon growth. Consequently, a specific sequence (leucine-arginine-glutamate, LRE) of the laminin beta 2 chain was proposed to act as a stop signal and to mediate specific reinnervation at the neuromuscular junction (Porter, B.E., J. Weis, and J.R. Sanes. 1995. Neuron. 14:549-559). We demonstrate here that native chick laminin-4, which contains the beta 2 chain and is present in the synaptic basement membrane, does not inhibit but rather promotes motor axon growth. In native heterotrimeric laminin, the LRE sequence of the beta 2 chain is found in a triple coiled-coil region that is formed by all three subunits. We show here that the effect of LRE depends on the structural context. Whereas a recombinant randomly coiled LRE peptide indeed inhibited outgrowth by chick motoneurons, a small recombinant triple coiled-coil protein containing this sequence did not.
肌肉去神经支配后，运动轴突会重新支配原来的突触位点。据报道，突触特异性层粘连蛋白β2链（s-层粘连蛋白）的重组片段可抑制运动轴突生长。因此，有人提出层粘连蛋白β2链的一个特定序列（亮氨酸-精氨酸-谷氨酸，LRE）可作为一种终止信号，并介导神经肌肉接头处的特异性再支配（波特，B.E.，J. 魏斯，和J.R. 萨内斯。1995年。《神经元》。第14卷：549 - 559页）。我们在此证明，天然鸡层粘连蛋白-4含有β2链且存在于突触基底膜中，它并不抑制反而促进运动轴突生长。在天然异三聚体层粘连蛋白中，β2链的LRE序列位于由所有三个亚基形成的三股卷曲螺旋区域。我们在此表明，LRE的作用取决于结构背景。虽然重组随机卷曲的LRE肽确实抑制了鸡运动神经元的生长，但含有该序列的小重组三股卷曲螺旋蛋白却没有。
