Mercado-Gómez Octavio, Landgrave-Gómez Jorge, Arriaga-Avila Virginia, Nebreda-Corona Adriana, Guevara-Guzmán Rosalinda
Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510 México, DF, Mexico.
Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510 México, DF, Mexico.
Epilepsy Res. 2014 Dec;108(10):1694-704. doi: 10.1016/j.eplepsyres.2014.09.019. Epub 2014 Oct 19.
Seizures have been shown to upregulate the expression of numerous extracellular matrix molecules. Tenascin C (TNC) is an extracellular matrix protein involved in several physiological roles and in pathological conditions. Though TNC upregulation has been described after excitotoxins injection, to date there is no research work on the signal transduction pathway(s) participating in TNC protein overproduction. The aim of this study was to evaluate the role of TGF-β signaling pathway on TNC upregulation. In this study, we used male rats, which were injected with saline or pilocarpine to induce status epilepticus (SE) and killed 24h, 3 and 7 days after pilocarpine administration. For evaluating biochemical changes, we measured protein content of TNC, TGF-β1 and phospho-Smad2/3 for localization of TNC in coronal brain hippocampus at 24h, 3 and 7 days after pilocarpine-caused SE. We found a significant increase of TNC protein content in hippocampal homogenates after 1, 3, and 7 days of pilocarpine-caused SE, together with an enhancement of TNC immunoreactivity in several hippocampal layers and the dentate gyrus field where more dramatic changes occurred. We also observed a significant enhancement of protein content of both the TGF-β1 and the critical downstream transduction effector phospho-Smad2/3 throughout the chronic exposure. Interestingly, animals injected with SB-431542, a TGF-β-type I receptor inhibitor, decreased TNC content in cytosolic fraction and diminished phospho-Smad2/3 content in both cytoplasmic and nuclear fraction compared with pilocarpine vehicle-injected. These findings suggest the participation of TGF-β signaling pathway on upregulation of TNC which in turn support the idea that misregulation of this signaling pathway produces changes that may contribute to disease.
癫痫发作已被证明可上调多种细胞外基质分子的表达。腱生蛋白C（TNC）是一种细胞外基质蛋白，参与多种生理作用及病理过程。尽管在注射兴奋性毒素后已观察到TNC上调，但迄今为止，尚无关于参与TNC蛋白过量产生的信号转导途径的研究报道。本研究的目的是评估转化生长因子-β（TGF-β）信号通路在TNC上调中的作用。在本研究中，我们使用雄性大鼠，给它们注射生理盐水或毛果芸香碱以诱导癫痫持续状态（SE），并在注射毛果芸香碱后24小时、3天和7天处死大鼠。为评估生化变化，我们在毛果芸香碱诱发SE后的24小时、3天和7天，测量了冠状脑海马中TNC、TGF-β1和磷酸化Smad2/3的蛋白含量，以确定TNC的定位。我们发现，在毛果芸香碱诱发SE后的1天、3天和7天，海马匀浆中TNC蛋白含量显著增加，同时在几个海马层和齿状回区域TNC免疫反应性增强，其中变化更为显著。我们还观察到，在整个慢性暴露过程中，TGF-β1和关键的下游转导效应物磷酸化Smad2/3的蛋白含量均显著增加。有趣地是，与注射毛果芸香碱溶媒的动物相比，注射TGF-β I型受体抑制剂SB-431542的动物，其细胞溶质部分的TNC含量降低，细胞质和细胞核部分的磷酸化Smad2/3含量均减少。这些发现表明TGF-β信号通路参与了TNC的上调，这反过来支持了这样一种观点，即该信号通路的失调产生的变化可能导致疾病。
