Rieger Débora K, Cunha Rodrigo M S, Lopes Mark William, Costa Ana Paula, Budni Josiani, Rodrigues Ana Lúcia S, Walz Roger, Teixeira Edson H, Nascimento Kyria S, Cavada Benildo S, Leal Rodrigo B
Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, 88040-900, Brazil.
J Mol Recognit. 2014 Dec;27(12):746-54. doi: 10.1002/jmr.2401.
In the central nervous system, many receptors, ion channels and neurotransmitter transporters are glycoproteins, where the glycan chains are modulator elements. Lectins are proteins, which recognize and bind carbohydrate complexes. We have previously shown that ConBr, a lectin purified from Canavalia brasiliensis seeds, produced antidepressant-like effect and blocked hippocampal neurotoxicity induced by quinolinic acid and glutamate. Noteworthy, all these effects occurred in a dependence of its carbohydrate recognition domain. Therefore, the present study was undertaken in order to elucidate intracellular signaling pathways regulated by ConBr that may be potentially associated with the antidepressant and neuroprotective effects previously reported to be dependent on carbohydrate interaction. ConBr (10 µg/site) was injected into the ventricle (i.c.v.) of mice, and the hippocampi were removed 0.5, 1, 3, 6, 8, 12, 18, and 24 h after treatment. Our results showed that in the period of 0.5-3 h, ConBr induced activation of the protein kinases Akt, ERK1, and PKA. Furthermore, the phosphorylation of CREB-Ser133 was stimulated by ConBr (1-6 h), while brain-derived neurotrophic factor (BDNF) mRNA was increased at 12 h and BDNF protein at 18-24 h. Our data suggest that an early activation of protein kinases may trigger CREB-dependent BDNF transcription, resulting in a subsequent increase of BDNF protein in response to ConBr. Later, increment of Akt phosphorylation was observed 24 h after ConBr administration, possibly due to BDNF/TrkB-dependent activation of Akt. Our findings indicate that ConBr is a multifunctional molecule capable to activate signaling pathways involved in neuroplasticity and neuroprotection.
在中枢神经系统中，许多受体、离子通道和神经递质转运体都是糖蛋白，其中糖链是调节元件。凝集素是能识别并结合碳水化合物复合物的蛋白质。我们之前已经表明，从巴西刀豆种子中纯化得到的凝集素ConBr具有抗抑郁样作用，并能阻断喹啉酸和谷氨酸诱导的海马神经毒性。值得注意的是，所有这些作用都依赖于其碳水化合物识别结构域。因此，本研究旨在阐明ConBr调节的细胞内信号通路，这些通路可能与先前报道的依赖于碳水化合物相互作用的抗抑郁和神经保护作用潜在相关。将ConBr（10μg/位点）注射到小鼠脑室（脑室内注射），并在处理后0.5、1、3、6、8、12、18和24小时取出海马体。我们的结果表明，在0.5 - 3小时内，ConBr诱导蛋白激酶Akt、ERK1和PKA的激活。此外，ConBr（1 - 6小时）刺激了CREB-Ser133的磷酸化，而脑源性神经营养因子（BDNF）mRNA在12小时增加，BDNF蛋白在18 - 24小时增加。我们的数据表明，蛋白激酶的早期激活可能触发CREB依赖的BDNF转录，从而导致随后对ConBr反应中BDNF蛋白的增加。后来，在ConBr给药24小时后观察到Akt磷酸化增加，这可能是由于BDNF/TrkB依赖的Akt激活。我们的研究结果表明，ConBr是一种多功能分子，能够激活参与神经可塑性和神经保护的信号通路。
