AMP蛋白激酶/RhoA信号通路在苯丙氨酸致神经损伤中的作用及机制探讨

Phenylketonuria (PKU), one of the most prevalent metabolic genetic disorders of amino acid metabolism, results from a severe deficiency in the activity of phenylalanine hydroxylase. Dysfunction of this hydroxylase, leads to abnormal accumulation of phenylalanine and its metabolites in the body, which cause severe brain injury and even mental retardation in untreated PKU patients. The exact pathogenetic mechanisms underlying phenylalanine and its metabolites-induced brain injury in this neurometabolic disorder have not yet been elucidated. Our previous in vitro experiments showed that high levels of phenylalanine inhibited the outgrowth of neuronal dendrites through activation of RhoA. Blocking RhoA signaling pathway could inhibit this effect. In addition, we demonstrated that in vitro phenylalanine stimulation at high concentrations upregulated neuronal AMPK phosphorylation.In this study, AMPK phosphorylation and RhoA activity in the cerebrocortical areas of PKU mice was determined and the effects of blocking AMPK/RhoA signaling pathway on the length and density of neuronal dendrites and dendrite spines in the cerebrocortical regions were studied,in order to demonstrate the role of AMPK/RhoA signaling pathway in PKU-associated brain injury. In vitro primary neuronal culture system was established to elucidate the effects of AMPK/RhoA on phenylalanine- induced inhibition of outgrowth of dendrites and dendrite spines and its interaction, which is helpful in in-depth understanding of the pathophysiology of PKU-associated brain injury and provides significant theoretical evidence for prevention and treatment of brain injury in PKU.

苯丙酮尿症(PKU)是最常见的氨基酸代谢障碍性遗传病，因苯丙氨酸羟化酶缺陷导致苯丙氨酸及多种酸性代谢物在体内堆积，引起脑损伤，患者出现严重智能落后。苯丙氨酸及其代谢物致脑损伤的确切机制尚未阐明。本课题组前期的体外实验研究表明：高苯丙氨酸能通过激活RhoA抑制神经元树突的生长，阻断RhoA 信号通路能改善苯丙氨酸诱导的神经元树突减少。与此同时，我们也发现体外高苯丙氨酸刺激能上调神经细胞AMPK的磷酸化水平。本课题将通过测定PKU小鼠大脑皮层中AMPK磷酸化和RhoA活性水平，以及阻断AMPK/RhoA信号通路对大脑皮层中树突及树突棘长度和密度的影响，来研究AMPK/RhoA信号通路在PKU脑损伤中的作用，在体外用原代培养的皮层神经细胞进一步探讨AMPK/RhoA对高苯丙氨酸抑制树突及树突棘生长的影响及其相互作用，这对深入理解PKU脑损伤的病理生理学机制，为防治PKU脑损伤提供重要的理论依据。