Brückner G, Grosche J, Schmidt S, Härtig W, Margolis R U, Delpech B, Seidenbecher C I, Czaniera R, Schachner M
Paul Flechsig Institute for Brain Research, University of Leipzig, D-04109 Leipzig, Germany.
J Comp Neurol. 2000 Dec 25;428(4):616-29. doi: 10.1002/1096-9861(20001225)428:4<616::aid-cne3>3.0.co;2-k.
The extracellular matrix glycoprotein tenascin-R (TN-R), colocalizing with hyaluronan, phosphacan, and aggregating chondroitin sulphate proteoglycans in the white and grey matter, is accumulated in perineuronal nets that surround different types of neurons in many brain regions. To characterize the role of TN-R in the formation of perineuronal nets, we studied their postnatal development in wild-type mice and in a TN-R knock-out mutant by using the lectin Wisteria floribunda agglutinin and an antibody to nonspecified chondroitin sulphate proteoglycans as established cytochemical markers. We detected the matrix components TN-R, hyaluronan, phosphacan, neurocan, and brevican in the perineuronal nets of cortical and subcortical regions. In wild-type mice, lectin-stained, immature perineuronal nets were first seen on postnatal day 4 in the brainstem and on day 14 in the cerebral cortex. The staining intensity of these nets for TN-R, hyaluronan, phosphacan, neurocan, and brevican was extremely weak or not distinguishable from that of the surrounding neuropil. However, all markers showed an increase in staining intensity of perineuronal nets reaching maximal levels between postnatal days 21 and 40. In TN-R-deficient animals, the perineuronal nets tended to show a granular component within their lattice-like structure at early stages of development. Additionally, the staining intensity in perineuronal nets was reduced for brevican, extremely low for hyaluronan and neurocan, and virtually no immunoreactivity was detectable for phosphacan. The granular configuration of perineuronal nets became more predominant with advancing age of the mutant animals, indicating the continued abnormal aggregation of chondroitin sulphate proteoglycans complexed with hyaluronan. As shown by electron microscopy in the cerebral cortex, the disruption of perineuronal nets was not accompanied by apparent changes in the synaptic structure on net-bearing neurons. The regional distribution patterns and the temporal course of development of perineuronal nets were not obviously changed in the mutant. We conclude that the lack of TN-R initially and continuously disturbs the molecular scaffolding of extracellular matrix components in perineuronal nets. This may interfere with the development of the specific micromilieu of the ensheathed neurons and adjacent glial cells and may also permanently change their functional properties.
细胞外基质糖蛋白腱生蛋白-R（TN-R）与透明质酸、磷蛋白聚糖以及聚集的硫酸软骨素蛋白聚糖共定位于白质和灰质中，在许多脑区围绕不同类型神经元的神经周网中积累。为了表征TN-R在神经周网形成中的作用，我们通过使用紫藤凝集素和针对非特异性硫酸软骨素蛋白聚糖的抗体作为既定的细胞化学标记，研究了其在野生型小鼠和TN-R基因敲除突变体中的出生后发育。我们在皮质和皮质下区域的神经周网中检测到了基质成分TN-R、透明质酸、磷蛋白聚糖、神经蛋白聚糖和短蛋白聚糖。在野生型小鼠中，凝集素染色的未成熟神经周网最早在出生后第4天出现在脑干，在第14天出现在大脑皮质。这些神经周网对TN-R、透明质酸、磷蛋白聚糖、神经蛋白聚糖和短蛋白聚糖的染色强度极其微弱，或与周围神经纤维网的染色强度无法区分。然而，所有标记物均显示神经周网的染色强度增加，在出生后第21天至40天之间达到最高水平。在TN-R缺陷动物中，神经周网在发育早期往往在其晶格状结构内显示出颗粒成分。此外，神经周网中短蛋白聚糖的染色强度降低，透明质酸和神经蛋白聚糖的染色强度极低，几乎检测不到磷蛋白聚糖的免疫反应性。随着突变动物年龄的增长，神经周网的颗粒状结构变得更加明显，表明与透明质酸复合的硫酸软骨素蛋白聚糖持续异常聚集。如大脑皮质的电子显微镜所示，神经周网的破坏并未伴随着承载神经网的神经元突触结构的明显变化。突变体中神经周网的区域分布模式和发育时间进程没有明显改变。我们得出结论，TN-R的缺乏最初并持续干扰神经周网中细胞外基质成分的分子支架。这可能会干扰被包裹神经元和相邻神经胶质细胞的特定微环境的发育，也可能会永久改变它们的功能特性。
