Miyata Shinji, Nadanaka Satomi, Igarashi Michihiro, Kitagawa Hiroshi
Laboratory of Molecular Bioregulation, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
Department of Biochemistry, Kobe Pharmaceutical University, Kobe, Japan.
Front Integr Neurosci. 2018 Feb 2;12:3. doi: 10.3389/fnint.2018.00003. eCollection 2018.
Aggrecan, a chondroitin sulfate (CS) proteoglycan, forms lattice-like extracellular matrix structures called perineuronal nets (PNNs). Neocortical PNNs primarily ensheath parvalbumin-expressing inhibitory neurons (parvalbumin, PV cells) late in brain development. Emerging evidence indicates that PNNs promote the maturation of PV cells by enhancing the incorporation of homeobox protein Otx2 and regulating experience-dependent neural plasticity. agglutinin (WFA), an plant lectin, binds to the CS chains of aggrecan and has been widely used to visualize PNNs. Although PNNs show substantial molecular heterogeneity, the importance of this heterogeneity in neural plasticity remains unknown. Here, in addition to WFA lectin, we used the two monoclonal antibodies Cat315 and Cat316, both of which recognize the glycan structures of aggrecan, to investigate the molecular heterogeneity of PNNs. WFA detected the highest number of PNNs in all cortical layers, whereas Cat315 and Cat316 labeled only a subset of PNNs. WFA, Cat315, and Cat316 PNNs showed different laminar distributions in the adult visual cortex. WFA, Cat315 and Cat316 detected distinct, but partially overlapping, populations of PNNs. Based on the reactivities of these probes, we categorized PNNs into four groups. We found that two subpopulation of PNNs, one with higher and one with lower WFA-staining are differentially labeled by Cat316 and Cat315, respectively. CS chains recognized by Cat316 were diminished in mice deficient in an enzyme involved in the initiation of CS-biosynthesis. Furthermore, WFA and Cat316 aggrecan were spatially segregated and formed microdomains in a single PNN. Otx2 co-localized with Cat316 but not with WFA aggrecan in PNNs. Our results suggest that the heterogeneity of PNNs around PV cells may affect the functional maturation of these cells.
聚集蛋白聚糖是一种硫酸软骨素（CS）蛋白聚糖，可形成称为神经元周围网（PNN）的晶格状细胞外基质结构。新皮质PNN主要在大脑发育后期包裹表达小白蛋白的抑制性神经元（小白蛋白，PV细胞）。新出现的证据表明，PNN通过增强同源框蛋白Otx2的掺入和调节经验依赖性神经可塑性来促进PV细胞的成熟。凝集素（WFA）是一种植物凝集素，可与聚集蛋白聚糖的CS链结合，并已被广泛用于可视化PNN。尽管PNN显示出大量的分子异质性，但这种异质性在神经可塑性中的重要性仍然未知。在这里，除了WFA凝集素外，我们还使用了两种单克隆抗体Cat315和Cat316，它们都识别聚集蛋白聚糖的聚糖结构，以研究PNN的分子异质性。WFA在所有皮质层中检测到的PNN数量最多，而Cat315和Cat316仅标记了一部分PNN。WFA、Cat315和Cat316 PNN在成年视觉皮质中显示出不同的层状分布。WFA、Cat315和Cat316检测到不同但部分重叠的PNN群体。根据这些探针的反应性，我们将PNN分为四组。我们发现，PNN的两个亚群，一个WFA染色较高，一个较低，分别被Cat316和Cat315差异标记。在缺乏参与CS生物合成起始的酶的小鼠中，Cat316识别的CS链减少。此外，WFA和Cat316聚集蛋白聚糖在单个PNN中在空间上分离并形成微结构域。在PNN中，Otx2与Cat316共定位，但不与WFA聚集蛋白聚糖共定位。我们的结果表明，PV细胞周围PNN的异质性可能会影响这些细胞的功能成熟。
