Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska, USA.
Glia. 2011 Jun;59(6):997-1007. doi: 10.1002/glia.21171. Epub 2011 Mar 24.
Microglia are critical cells in mediating the pathophysiology of neurodegenerative disorders such as HIV-associated neurocognitive disorders. We hypothesize that HIV-1 glycoprotein 120 (gp120) activates microglia by enhancing outward K(+) currents, resulting in microglia secretion of neurotoxins, consequent neuronal dysfunction, and death. To test this hypothesis, we studied the effects of gp120 on outward K(+) current in cultured rat microglia. Application of gp120 enhanced outward K(+) current in a dose-dependent manner, which was blocked by voltage-gated K(+) (K(v) ) channel blockers. Western blot analysis revealed that gp120 produced an elevated expression of K(v) channel proteins. Examination of activation and inactivation of outward K(+) currents showed that gp120 shifted membrane potentials for activation and steady-state inactivation. The gp120-associated enhancement of outward K(+) current was blocked by either a CXCR4 receptor antagonist T140 or a specific protein kinase A (PKA) inhibitor H89, suggesting the involvement of chemokine receptor CXCR4 and PKA in gp120-mediated enhancement of outward K(+) current. Biological significance of gp120-induced enhancement of microglia outward K(+) current was demonstrated by experimental results showing the neurotoxic activity of gp120-stimulated microglia, evaluated by TUNEL staining and MTT assay, significantly attenuated by K(v) channel blockers. Taken together, these results suggest that gp120 induces microglia neurotoxic activity by enhancing microglia outward K(+) current and that microglia K(v) channels may function as a potential target for the development of therapeutic strategies.
小胶质细胞在介导神经退行性疾病（如 HIV 相关神经认知障碍）的病理生理学中起着关键作用。我们假设 HIV-1 糖蛋白 120（gp120）通过增强外向 K(+)电流激活小胶质细胞，导致小胶质细胞分泌神经毒素，继而导致神经元功能障碍和死亡。为了验证这一假设，我们研究了 gp120 对培养的大鼠小胶质细胞外向 K(+)电流的影响。gp120 的应用以剂量依赖性方式增强外向 K(+)电流，该电流被电压门控 K(+)（K(v)）通道阻断剂阻断。Western blot 分析显示，gp120 导致 K(v)通道蛋白表达升高。外向 K(+)电流的激活和失活的检测表明，gp120 改变了激活和稳态失活的膜电位。gp120 相关的外向 K(+)电流增强被 CXCR4 受体拮抗剂 T140 或特定的蛋白激酶 A（PKA）抑制剂 H89 阻断，表明趋化因子受体 CXCR4 和 PKA 参与了 gp120 介导的外向 K(+)电流增强。实验结果表明，gp120 刺激的小胶质细胞的神经毒性活性通过 TUNEL 染色和 MTT 测定评估，gp120 诱导的小胶质细胞外向 K(+)电流增强被 K(v)通道阻断剂显著减弱，证明了 gp120 诱导的小胶质细胞外向 K(+)电流增强的生物学意义。总之，这些结果表明，gp120 通过增强小胶质细胞外向 K(+)电流诱导小胶质细胞神经毒性活性，而小胶质细胞 K(v) 通道可能是开发治疗策略的潜在靶点。
