内皮素-1 诱导的增殖减少，内皮素 B 缺陷型视神经头星形胶质细胞中的 Ca²⁺信号增强。
Endothelin-1-induced proliferation is reduced and Ca²⁺ signaling is enhanced in endothelin B-deficient optic nerve head astrocytes.
机构信息
Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada.
出版信息
Invest Ophthalmol Vis Sci. 2011 Sep 29;52(10):7771-7. doi: 10.1167/iovs.11-7699.
PURPOSE
To characterize the influence of endothelin-1 (ET-1) on optic nerve head astrocyte (ONHA) proliferation and Ca²⁺ signaling in ONHAs lacking functional endothelin B (ETB) receptors.
METHODS
ONHAs were isolated from adult wild type (WT) and transgenic spotting lethal (TSL) rats, lacking functional ETB receptors. ONHA specificity was confirmed by positive glial fibrillary acidic protein (GFAP), negative A2B5 (a marker for type II astrocytes located outside the optic nerve head) and myelin basic protein (MBP) labeling. The mitogenic effects of 10⁻⁷ or 10⁻⁹ M ET-1, or vehicle were investigated for 48 or 72 hours in WT and TSL ONHAs. Intracellular calcium levels (Ca²⁺) were assessed in ONHAs loaded with fura-2 calcium indicator dye.
RESULTS
ET-1-induced proliferation of TSL ONHAs was blunted at 48 hours (by 37% at 10⁻⁷ M and by 33% at 10⁻⁹ M) and 72 hours (by 117% at 10⁻⁷ M and by 100% at 10⁻⁹ M) compared with WT cells. ET-1-induced ONHA fura-2 ratio increases were significantly greater in TSL ONHAs (by 20% at 10⁻⁷ M and by 48% at 10⁻⁹ M) compared with WT ONHAs. ET-1-induced fura-2 ratio increases were blocked after pretreatment with BQ-610 (ETA antagonist) in WT and TSL ONHAs, but not by BQ-788 (ETB antagonist) in WT ONHAs.
CONCLUSIONS
ET-1-induced ONHA proliferation is reduced in cells lacking functional ETB receptors, ET-1-induced Ca²⁺ increases are enhanced in the absence of functional ETB receptors, and ETA, but not ETB, is required for ET-1-induced Ca²⁺ elevation.
目的
研究内皮素-1（ET-1）对缺乏功能性内皮素 B（ETB）受体的视神经头星形胶质细胞（ONHA）增殖和 Ca²⁺信号的影响。
方法
从成年野生型（WT）和转基因斑点致死（TSL）大鼠中分离出 ONHA，这些大鼠缺乏功能性 ETB 受体。通过胶质纤维酸性蛋白（GFAP）阳性、A2B5（位于视神经头外的 II 型星形胶质细胞标志物）和髓鞘碱性蛋白（MBP）阴性标记物来确认 ONHA 的特异性。用 10⁻⁷ 或 10⁻⁹ M ET-1 或载体处理 WT 和 TSL ONHA 48 或 72 小时，研究其有丝分裂作用。用 fura-2 钙指示剂染料负载 ONHA 后，评估细胞内钙水平(Ca²⁺)。
结果
与 WT 细胞相比，ET-1 诱导的 TSL ONHA 增殖在 48 小时（10⁻⁷ M 时减少 37%，10⁻⁹ M 时减少 33%）和 72 小时（10⁻⁷ M 时增加 117%，10⁻⁹ M 时增加 100%）时受到抑制。与 WT ONHA 相比，ET-1 诱导的 TSL ONHA fura-2 比值增加明显更大（10⁻⁷ M 时增加 20%，10⁻⁹ M 时增加 48%）。在 WT 和 TSL ONHA 中，用 BQ-610（ETA 拮抗剂）预处理后可阻断 ET-1 诱导的 fura-2 比值增加，但在 WT ONHA 中用 BQ-788（ETB 拮抗剂）预处理则不能阻断。
结论
缺乏功能性 ETB 受体的 ONHA 增殖减少，在缺乏功能性 ETB 受体的情况下，ET-1 诱导的 Ca²⁺ 增加增强，而 ET-1 诱导的 Ca²⁺ 升高需要 ETA，而不是 ETB。
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