Selective protection of murine cerebral Gi/o-proteins from inactivation by parenterally injected pertussis toxin
Selective protection of murine cerebral Gi/o-proteins from inactivation by parenterally injected pertussis toxin
复制标题
DOI：
10.1007/s00109-019-01854-1
复制
发表时间：
2020-01-01
影响因子：
4.7
通讯作者：
Nuernberg, Bernd
中科院分区：
文献类型：
--
作者：
Vega, Salvador Castaneda;Leiss, Veronika;Nuernberg, Bernd
百日咳毒素（PTX）是百日咳患者中的一种强效毒力因子，但其解毒版本可用于疫苗接种。它被认为有助于疾病的病理学，包括各种CNS功能障碍。基于其酶活性，PTX通过修饰异源三聚体G（i/o）蛋白的α亚基来破坏GPCR依赖性信号传导。它也被广泛用作研究体内和体外神经元功能的研究工具。然而，证明PTX从血液渗透到大脑的数据缺失。在这里，我们检查了G α（i/o）修饰活性的PTX在小鼠脑后，其胃肠外应用。[I-124]-PTX的离体生物分布分析显示，脑分布较差，而胰腺中可见相对较高的浓度。PTX影响中枢神经系统和胰腺内分泌功能，分别通过旷场和葡萄糖耐量试验显示。然而，虽然胰岛G α（i/o）-蛋白被修饰，但它们在脑组织中的神经元对应物对PTX具有抗性，如不同的放射自显影和免疫印迹SDS-PAGE分析所示。相比之下，PTX容易在体外修饰脑G α（i/o）-蛋白。通过应用高渗甘露醇来增加BBB通透性的尝试没有显示对神经元G蛋白的PTX活性。与这些发现一致，体内MRI分析并未指出PTX治疗后血脑屏障（BBB）通透性增加。我们的数据表明，中枢神经系统是保护免受PTX。因此，我们假设BBB阻碍PTX渗透到CNS中并将其酶活性递送到脑G α（i/o）-蛋白。关键信息i.p.应用的PTX在脑中保留较差，而在胰腺中达到高浓度。腹膜内给予PTX可修饰胰岛G α i/o-蛋白，但不修饰脑G α i/o-蛋白。来自分离的脑细胞膜的G α i/o-蛋白容易被PTX离体修饰。保护CNS免受腹膜内给予的PTX。PTX不透化BBB。
Pertussis toxin (PTX) is a potent virulence factor in patients suffering from whooping cough, but in its detoxified version, it is applied for vaccination. It is thought to contribute to the pathology of the disease including various CNS malfunctions. Based on its enzymatic activity, PTX disrupts GPCR-dependent signaling by modifying the alpha-subunit of heterotrimeric G(i/o)-proteins. It is also extensively used as a research tool to study neuronal functions in vivo and in vitro. However, data demonstrating the penetration of PTX from the blood into the brain are missing. Here, we examined the G alpha(i/o)-modifying activity of PTX in murine brains after its parenteral application. Ex vivo biodistribution analysis of [I-124]-PTX displayed poor distribution to the brain while relatively high concentrations were visible in the pancreas. PTX affected CNS and endocrine functions of the pancreas as shown by open-field and glucose tolerance tests, respectively. However, while pancreatic islet G alpha(i/o)-proteins were modified, their neuronal counterparts in brain tissue were resistant towards PTX as indicated by different autoradiographic and immunoblot SDS-PAGE analyses. In contrast, PTX easily modified brain G alpha(i/o)-proteins ex vivo. An attempt to increase BBB permeability by application of hypertonic mannitol did not show PTX activity on neuronal G proteins. Consistent with these findings, in vivo MRI analysis did not point to an increased blood-brain barrier (BBB) permeability following PTX treatment. Our data demonstrate that the CNS is protected from PTX. Thus, we hypothesize that the BBB hinders PTX to penetrate into the CNS and to deliver its enzymatic activity to brain G alpha(i/o)-proteins. Key messagesi.p. applied PTX is poorly retained in the brain while reaches high concentration in the pancreas. Pancreatic islet G alpha i/o- but not cerebral G alpha i/o-proteins are modified by i.p. administered PTX. G alpha i/o-proteins from isolated cerebral cell membranes were easily modified by PTX ex vivo. CNS is protected from i.p. administered PTX. PTX does not permeabilize the BBB.