Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, China.
Department of Anesthesiology and Perioperative Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.
J Cell Physiol. 2019 Nov;234(11):20847-20858. doi: 10.1002/jcp.28689. Epub 2019 Apr 19.
Astrocyte undergoes morphology changes that are closely associated with the signaling communications at synapses. N-myc downstream-regulated gene 2 (NDRG2) is specifically expressed in astrocytes and is associated with several important astrocyte functions, but its potential role(s) relating to astrocyte morphological changes remain unknown. Here, primary astrocytes were prepared from neonatal Ndrg2 and Ndrg2 pups, and the drug Y27632 was used to induce stellation. We then used a variety of methods to measure the levels of NDRG2, α-Actinin4, and glial fibrillary acidic protein (GFAP), and the activity of RhoA, Rac1, and Cdc42 in Y27632-treated astrocytes as well as in Ndrg2 , Ndrg2 , or Ndrg2 + lentivirus (restore NDRG2 expression) astrocytes. We also conducted live-imaging and proteomics studies of the cultured astrocytes. We found that induction of astrocytes stellation (characterized by cytoplasmic retraction and process outgrowth) resulted in increased NDRG2 protein expression and Rac1 activity and in reduced α-Actinin4 protein expression and RhoA activity. Ndrg2 deletion induced astrocyte flattening, whereas the restoration of NDRG2 expression induced stellation. Ndrg2 deletion also significantly increased α-Actinin4 protein expression and RhoA activity yet reduced GFAP protein expression and Rac1 activity, and these trends were reversed by restoration of NDRG2 expression. Collectively, our results showed that Ndrg2 deletion promoted cell proliferation, interrupted stellation capability, and extensively altered the protein expression profiles of proteins that function in Rho-GTPase signaling. These findings suggest that NDRG2 functions to regulate astrocytes morphology via altering the accumulation of the Rho-GTPase signaling pathway components, thereby supporting that NDRG2 should be understood as a regulator of synaptic plasticity and thus neuronal communications.
星形胶质细胞经历形态变化，这些变化与突触处的信号通讯密切相关。N- MYC 下游调节基因 2（NDRG2）特异性表达于星形胶质细胞，并与几种重要的星形胶质细胞功能相关，但它与星形胶质细胞形态变化相关的潜在作用尚不清楚。在这里，我们从新生 Ndrg2 和 Ndrg2 幼鼠中制备原代星形胶质细胞，并使用药物 Y27632 诱导星形胶质细胞星状化。然后，我们使用多种方法来测量 Y27632 处理的星形胶质细胞以及 Ndrg2 、 Ndrg2 或 Ndrg2 + 慢病毒（恢复 NDRG2 表达）星形胶质细胞中 NDRG2、α-辅肌动蛋白 4 和神经胶质纤维酸性蛋白（GFAP）的水平，以及 RhoA、Rac1 和 Cdc42 的活性。我们还对培养的星形胶质细胞进行了实时成像和蛋白质组学研究。我们发现，诱导星形胶质细胞星状化（特征为细胞质回缩和突起生长）导致 NDRG2 蛋白表达增加和 Rac1 活性增强，α-辅肌动蛋白 4 蛋白表达减少和 RhoA 活性降低。Ndrg2 缺失诱导星形胶质细胞变平，而恢复 NDRG2 表达则诱导星状化。Ndrg2 缺失还显著增加了 α-辅肌动蛋白 4 蛋白表达和 RhoA 活性，同时降低了 GFAP 蛋白表达和 Rac1 活性，而这些趋势通过恢复 NDRG2 表达得到逆转。总的来说，我们的结果表明，Ndrg2 缺失促进细胞增殖，中断了星状化能力，并广泛改变了在 Rho-GTPase 信号转导中起作用的蛋白质的蛋白表达谱。这些发现表明，NDRG2 通过改变 Rho-GTPase 信号通路成分的积累来调节星形胶质细胞形态，从而支持 NDRG2 应该被理解为突触可塑性的调节剂，进而支持神经元通讯。
