Phenylalanine activates the mitochondria-mediated apoptosis through the RhoA/Rho-associated kinase pathway in cortical neurons.
Phenylketonuria (PKU) is caused by deficiency of phenylalanine hydroxylase, resulting in an accumulation of phenylalanine in brain tissue and cerebrospinal fluid of phenylketonuria patients. Phenylketonuria is neuropathologically characterized by neuronal cell loss, white matter abnormalities, dendritic simplification, and synaptic density reduction. The neuropathological effect may be due to the "toxicity" of the high concentration of phenylalanine, while the underlying mechanism remains unclear. In this study, we found that cultured cerebral cortical neurons underwent mitochondria-mediated apoptosis when exposed to phenylalanine. We further demonstrated that phenylalanine induced RhoA activation. Phenylalanine also promoted myosin light chain (MLC) phosphorylation, which might be the result of the activation of Rho-associated kinase (ROCK). The RhoA antagonist, C3 transferase (C3), Rho-associated kinase specific inhibitor, Y-27632, and the overexpression of either dominant negative RhoA or dominant negative Rho-associated kinase inhibited phenylalanine-induced caspase-3 activation and rescued neurons from apoptosis, indicating that the RhoA/Rho-associated kinase signalling pathway plays an important role in phenylalanine-induced neuronal apoptosis.
Zhang
Yongjun
Y
XinHua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China. shanghaiyjzhang@yahoo.com.cn
Gu
Xuefan
X
Yuan
Xiaobing
X
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020287:In Situ Nick-End Labeling / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure; D018696:Neuroprotective Agents / Q000494:pharmacology; D010649:Phenylalanine / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013997:Time Factors; D014162:Transfection / Q000379:methods; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
D000590:Amino Acid Chloromethyl Ketones; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D018696:Neuroprotective Agents; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D049452:Green Fluorescent Proteins; D010649:Phenylalanine; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D053148:Caspase 3; D020742:rhoA GTP-Binding Protein