Funchal Cláudia, Dall Bello Pessutto Franciele, de Almeida Lúcia Maria Vieira, de Lima Pelaez Priscila, Loureiro Samanta Oliveira, Vivian Lilian, Wajner Moacir, Pessoa-Pureur Regina
Universidade Federal do Rio Grande do Sul, Instituto de Ciências Básicas da Saúde, Departamento de Bioquímica, Rua Ramiro Barcelos 2600 anexo, 90035-003 Porto Alegre, RS, Brazil.
J Neurol Sci. 2004 Jan 15;217(1):17-24. doi: 10.1016/j.jns.2003.08.003.
In this study we investigated the effects of alpha-ketoisovaleric (KIV) and alpha-keto-beta-methylvaleric acids (KMV), metabolites accumulating in the inherited neurometabolic disorder maple syrup urine disease (MSUD), on the in vitro incorporation of 32P into intermediate filament (IF) proteins from cerebral cortex of young rats during development (9-21 days of age) We observed that KMV significantly increased the in vitro incorporation of 32P into the IF proteins studied in cortical slices of 12-day-old rats through the PKA and PKCaMII, with no alteration at the other ages. In contrast, KIV was ineffective in altering the phosphorylating system associated with IF proteins at all ages examined. A similar effect on IF phosphorylation was achieved by incubating cortical slices with gamma-aminobutiric acid (GABA). Furthermore, by using specific GABA antagonists, we verified that KMV induced a stimulatory effect on IF phosphorylation of tissue slices from 12-day-old rats mediated by GABA(A) and GABA(B) receptors. In conclusion, our results indicate the involvement of the GABAergic system in the alterations of IF phosphorylation caused by KMV, one of the branched-chain keto acids accumulating in MSUD.
在本研究中，我们调查了α-酮异戊酸（KIV）和α-酮-β-甲基戊酸（KMV）这两种在遗传性神经代谢疾病枫糖尿症（MSUD）中积累的代谢产物，对幼鼠发育过程中（9至21日龄）大脑皮质中间丝（IF）蛋白体外掺入32P的影响。我们观察到，KMV通过蛋白激酶A（PKA）和钙调蛋白依赖激酶II（PKCaMII）显著增加了12日龄大鼠皮质切片中所研究的IF蛋白的32P体外掺入量，在其他年龄则无变化。相比之下，在所有检测的年龄中，KIV对与IF蛋白相关的磷酸化系统均无作用。用γ-氨基丁酸（GABA）孵育皮质切片对IF磷酸化产生了类似的影响。此外，通过使用特异性GABA拮抗剂，我们证实KMV对12日龄大鼠组织切片IF磷酸化的刺激作用是由GABA(A)和GABA(B)受体介导的。总之，我们的结果表明，GABA能系统参与了由KMV引起的IF磷酸化改变，KMV是MSUD中积累的支链酮酸之一。
