| Abstract: | 許多研究指出中樞神經系統的胰島素訊號受損與神經退化性疾病包含阿茲海默病(Alzheimer’s Disease, AD)、路易氏體失智症(Dementia of Lewy bodies, DLB)及亨丁頓舞蹈症(Huntington’s disease, HD)之間存在緊密關聯性，因此胰島素阻抗可能在這些腦部疾病的發病機制中扮演重要的角色。直至現今，使用病毒載體的基因治療仍然是治療遺傳及非遺傳性疾病的治療策略，但是此方法仍有很多問題及風險尚待克服。在本研究中，我們證明F6 (糖醇類化合物glycylglycerin與miR-302之混合物)能夠透過直接進入神經細胞，並透過恢復受損的胰島素訊息達到神經保護的作用。在第一部分研究中，結果顯示F6透過靶向PTEN基因使得Akt訊息活化，且同時刺激了Nanog表現抑制了Aβ導致的神經胰島素阻抗。此外，F6能夠調節AMPK/Sirt1訊息路徑緩解Aβ所引起的粒線體功能損傷及氧化壓力傷害，並且因此促進自噬作用與延緩細胞老化。在第二部分研究中，我們使用條件式誘導αSyn蛋白大量表現後加入Aβ模擬DLB患者腦部的病理情況。透過DLB的細胞模式，結果顯示F6能夠刺激Nanog表現對抗Aβ加成αSyn所導致的胰島素阻抗，並且透過活化自噬減緩了粒線體損傷和氧化壓力及延緩衰老。在最後一部分的研究中，我們透過轉染HttQ74模擬HD的疾病模式，探討F6是否能夠透過與前兩部分研究的類似訊息路徑達到神經保護作用。已知突變的HTT蛋白會破壞自噬作用的活性，導致神經細胞內大量的錯誤蛋白質聚集引起嚴重的神經毒性。在本部分中我們證實了F6能夠透過活化Sirt1訊息路徑恢復正常的自噬活性，進而減緩了HttQ74所誘導的粒線體損傷及氧化壓力傷害。此外，F6同樣透過活化Nanog訊息改善了HttQ74所導致的胰島素訊號受損並且延緩了異常的提早衰老現象。綜合以上，我們推論F6可透過回復神經胰島素訊息活性，提升了自噬活性及對抗衰老達到神經保護的效果。
Many studies have shown an association between impaired CNS insulin signaling and neurodegenerative disorders including Alzheimer’s Disease (AD), Dementia of Lewy bodies (DLB) and Huntington’s disease (HD), suggesting that insulin resistance might play an important role in the pathogenesis of these brain diseases. Up to the present, using a virus to conduct gene therapy is an important avenue to treatment of a large number of diseases both heritable and acquired, but numerous problems and risks exist that prevent using viral vectors. In this study, we demonstrated F6 (a mixture of glycylglycerin and miR-302) directly enters into neuronal cells to provide neuroprotection through restoring impaired insulin signaling. In the first part, the results showed that F6 activated Akt signaling through targeting PTEN, which subsequently stimulated Nanog expression to suppress Aβ-induced insulin resistance. In addition, we also found that F6 stimulates autophagy through regulating AMPK/Sirt1 signaling to alleviate Aβ-induced mitochondria dysfunction and oxidative stress. Overall, the restored insulin signaling and decreased autophagy activity may be associated with F6-mediated aging delaying. In the second part, we developed a conditional approach to induce α-synuclein overexpression, and co-treated Aβ to simulate the pathological condition similar to DLB brains. By using this in vitro model, our results showed that F6 stimulated-Nanog expression suppressed Aβ-induced insulin signaling impairments in αSyn‐overexpressed cells. Also, F6 regulated Sirt1 signaling to alleviate mitochondria dysfunction and oxidative stress though activating autophagy and delaying aging processes. In the last part, we induced HD disease condition through transient transfection of HttQ74 vector to investigate whether F6 provides neuroprotection though similar pathways similar to the first two parts. As we have known, mutant huntingtin protein leads to serious neurotoxicity and damages autophagy flux, resulting in protein aggregation in affected neuronal cells. We demonstrated F6 may activates Sirt1 signaling to restore the autophagy function, which alleviates HttQ74-induced mitochondria dysfunction and oxidative stress. Additionally, F6 stimulated Nanog expression to suppress HttQ74-induced insulin resistance and delayed aging processes. Based on our findings, F6 may provide neuroprotection through restoration of impaired insulin signaling, promotion of autophagy activity and attenuation of aging processes. |
