2011-08-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/656647摘要：神經精神病變是一種人類社會獨特且盛行率高的慢性疾病。通常這一類疾病會在青少年時期發作、並須經過多年病程方使得此種病情完全發作。過去的流行病學研究咸認為精神病變係肇因於多重基因因子與環境因子的交互複雜作用。雖然近年來基因體醫學及非侵入性之生物影像技術高度發展，但人類精神病變真正的致病機轉及其生物功能之全貌仍未能完全得知。近十年的研究漸漸認可精神病變是一種神經發育的疾病。特別針對精神官能分裂症(schizophrenia), 其由 genetic linkage analysis所找出之致病危險因子(susceptibility risk factors)如neuregulin, ErbB, BACE1, 和DISC1, 皆在實驗動物模式中被加以證實在胚胎神經發育中扮演重要角色。而藉由實驗動物疾病模式的研究，定義明確之生物傳導訊息及細胞與分子生物之作用機制可因此而被發現，並進一步被應用到治療標的之設計及新藥物分子之效能篩檢。是以藉此實驗動物疾病模式的研究， DISC1 被發現在神經發育過程中，在神經細胞內藉由與不同分子在不同的胞器位子交互作用，來調控包括神經母細胞分裂增生（progenitor cell proliferation）、神經細胞移動路徑（radialmigration）、神經細胞樹突分枝形態 (dendritic arborization )、及神經細胞彼此接觸訊息傳導之突觸的建立（synapse formation )等多方面之生物功能。我們實驗室經由yeast-two-hybrid 和 coimmunoprecipitation 實驗，發現 DISC1 和 Fbxl14 (F-box andleucine-rich repeat protein 14) 可互相作用而形成蛋白複合体。 Fbxl14 是一藉由人類基因體研究所發現之新穎基因，並在2004年被標誌為一種屬於 F-Box proteins 家族之新成員。至今，Fbxl14之生物功能仍未被研究揭曉。我們觀察到的Fbxl14與DISC1交互作用之新發現，令我們合理的假設 Fbxl14在 DISC1所調控之神經發育過程中扮演某種角色，並且可能參與由DISC1基因變異所衍生之精神病變。所有F-box proteins皆在其蛋白質N-端含有 F-box domain，此 domain 被用於和Cullin、Skp 形成 SCF complex因而具有 E3 ligase 活性，可在被辨認之受體進行ubiquitination。目前已知的F-box proteins生物功能包括細胞分裂週期調控（cell cycleprogression), 生物時鐘週期（the circadian rhythm), 和巴金森氏症 (Parkison’s disease) 。近年實驗動物之基因研究更顯示F-box proteins參與調控神經發育包括突觸的建立（synapse formation), 突觸的排除 （synapse elimination) 和神經軸突路徑之導引及建立（axonal trajectory involved for correct wiring of neural circuitry)。有趣的是，我們觀察到在不同發育時期的鼠胚大腦其 Fbxl14與DISC1表現區域有大部份的重疊或雷同，顯示Fbxl14與DISC1兩者可能在胚胎神經系統發育中有功能性之交互作用。而最近甚且有報導一臨床病例，其將過動/注意力缺失症狀連結到可能肇因於Fbxl14之缺失。是以，更加顯示Fbxl14與調控精神功能之神經發育有某種程度之相關。我們之前已產出 Fbxl14基因剔除鼠（Fbxl14-knockout mouse）及Fbxl14低功效鼠（Fbxl14-hypomorph mouse）--亦即ENU突變鼠P131。ENU突變鼠P131經由我們的研究，已證實其帶有 missense mutated Fbxl14(T370A)。另外，我們和Dr. HJ Cheng at UC, Davis合作，於 C. elegans 成功的建立heterologous mDISC1 transgenic system，藉以評估與schizophrenia相關之細胞與分子生物和相關訊息傳導機制。而此 C. elegans動物模式亦被我們證實可運用於抗精神藥物之藥效評估。 是以，我們於本計畫提出經由研究這些動物模式，以揭示 Fbxl14在胚胎神經發育之功能及其與DISC1如何共同調控與認知功能相關之神經發育與神經精神病變。<br> Abstract: Neuropsychiatric diseases such as schizophrenia, bipolar disorder, autism, and majordepression are chronic debilitating and highly prevalent, all of which are generally caused bya combination of genetic factors and environmental insults. Despite the rapid progress innoninvasive imaging technology and advance in human genomics, the biology of mentalillness is incompletely understood. Accumulating evidences indicate that mental illness is aneurodevelopmental disorder. In particular, previous human genetic linkage analyses forschizophrenia have identified susceptibility risk factors, all of which play important roles inneurodevelopment. DISC1 (disrupted-in-schizophrenia 1) is one of such genes. Geneticallyengineered animal models of DISC1 provide defined mechanisms of pathogenesis, suggestingthat DISC1 mediates various neurodevelopmental processes including neural progenitor cellproliferation, radial migration, dendritic arborization, and synapse formation by selectiveinteraction with different proteins in different subcellular compartments. Our pioneer studyvia yeast-two-hybrid and coimmunoprecipitation assay has identified Fbxl14 (F-box andleucine-rich repeat protein 14) interacts with DISC1. Fbxl14, annotated in 2004, is a novelmember of F-Box proteins and remains functionally unknown. The fact that DISC1 formsprotein complex with Fbxl14 prompts us to investigate Fbxl14’s involvement inDISC1-mediated neurodevelopmental processes as well as DISC1-related neuropathy.F-box proteins (FBPs) are a group of evolutionarily conserved proteins sharing F-boxdomain at the N-terminus. They mediate a wide variety of cellular and pathological processesthat include cell cycle progression, synapse formation, regulation of circadian rhythm, andformation of Parkison’s disease. Recent genetic studies highlight the critical role of FBPs as asubunit of E3 ubiquitin ligase SCF complex in regulating synapse formation, synapseelimination and axon guidance. Intriguingly, our pioneer study shows that Fbxl14 is expressedin the neocortex and other brain regions of developing mouse embryos with temporal andspatial regulated patterns concordant with DISC1 expression. Noticeably, a clinical case withattention-deficit/hyperactive disorder and developmental delay has recently been linked withdeletion of a locus harboring Fbxl14 gene, further suggesting Fbxl14’s involvement in neuraldevelopment.To study how Fbxl14 interacts with DISC1 to regulate neural development, we haveobtained an ENU mutant mouse line (called P131) that is a FBXl14 hypomorph with amissense Fbxl14(T370A) mutation. We have also generated a null mutant of Fbxl14. By collaboration with Dr. HJ Cheng at UC, Davis, we also established a heterologous mDISC1transgenic system in C. elegans motor neurons that has been demonstrated as a heterologousanimal model for schizophrenia. Moreover, we have demonstrated that such heterologousmDISC1 transgenic model is useful to evaluate the effect of anti-psychotic drugs, suggestingthe potential to screen for small molecules or chemicals with therapeutic effects onDISC1-related abnormalities. With these animal models in hand, we aim to uncover thebiology of FBXL14 in the development of the nervous system and its pathological role inDISC1-mediated schizophrenia.Fbxl14DISC1精神官能分裂症神經組織Fbxl14基因剔除鼠DISC1schizophreniaFbxl14neuron-specific fbxl14-null mouse