The physiological AKT-MTORC1 and AMPK signaling pathways are considered key nodes in the regulation of anabolism-catabolism, and particularly of macroautophagy/autophagy. Indeed, it is reported that these are altered processes in neurodegenerative proteinopathies such as Alzheimer disease (AD), mainly characterized by deposits of β-amyloid (Aβ) and hyperphosphorylated MAPT. These accumulations disrupt the optimal neuronal proteostasis, and hence, the recovery/enhancement of autophagy has been proposed as a therapeutic approach against these proteinopathies. The purpose of the present study was to characterize the modulation of autophagy by MTORC1 and AMPK signaling pathways in the highly specialized neurons, as well as their repercussions on Aβ production. Using a double transgenic mice model of AD, we demonstrated that MTORC1 inhibition, either in vivo or ex vivo (primary neuronal cultures), was able to reduce amyloid secretion through moderate autophagy induction in neurons. The pharmacological prevention of autophagy in neurons augmented the Aβ secretion and reversed the effect of rapamycin, confirming the anti-amyloidogenic effects of autophagy in neurons. Inhibition of AMPK with compound C generated the expected decrease in autophagy induction, though surprisingly did not increase the Aβ secretion. In contrast, increased activity of AMPK with metformin, AICAR, 2DG, or by gene overexpression did not enhance autophagy but had different effects on Aβ secretion: whereas metformin and 2DG diminished the secreted Aβ levels, AICAR and PRKAA1/AMPK gene overexpression increased them. We conclude that AMPK has a significantly different role in primary neurons than in other reported cells, lacking a direct effect on autophagy-dependent amyloidosis.Abbreviations: 2DG: 2-deoxy-D-glucose; Aβ: β-amyloid; ACACA: acetyl-CoA carboxylase alpha; ACTB: actin beta; AD: Alzheimer disease; AICAR: 5-aminoimidazole-4-carboxamide-1-β-riboside; AKT: AKT kinases group (AKT1 [AKT serine/threonine kinase 1], AKT2 and AKT3); AMPK: adenosine 5'-monophosphate (AMP)-activated protein kinase; APP: amyloid beta precursor protein; APP/PSEN1: B6.Cg-Tg (APPSwe, PSEN1dE9) 85Dbo/J; ATG: autophagy related; ATP: adenosine triphosphate; BafA1: bafilomycin A1; CA: constitutively active; CGN: cerebellar granule neuron; CoC/compound C: dorsommorphin dihydrochloride; ELISA: enzyme-linked immunosorbent assay; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; Gmax: GlutaMAX™; IN1: PIK3C3/VPS34-IN1; KI: kinase-inactive; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3; MAPT/TAU: microtubule associated protein tau; Metf: metformin; MRT: MRT68921; MTORC1: mechanistic target of rapamycin kinase complex 1; NBR1: NBR1 autophagy cargo receptor; PRKAA: 5'-AMP-activated protein kinase catalytic subunit alpha; PtdIns3K: phosphatidylinositol 3-kinase; Rapa: rapamycin; RPS6KB1/S6K: ribosomal protein S6 (RPS6) kinase polypeptide 1; SCR: scramble; SQSTM1/p62: sequestosome 1; ULK1/2: unc-51 like autophagy activating kinase 1/2; WT: wild type.

中文翻译：

---

与 MTORC1 抑制相比，AMPK 激活不会增强神经元中的自噬：对 β-淀粉样蛋白清除的不同影响。

生理学 AKT-MTORC1 和 AMPK 信号通路被认为是调节合成代谢-分解代谢，尤其是巨自噬/自噬的关键节点。事实上，据报道，这些是神经退行性蛋白质病如阿尔茨海默病 (AD) 的改变过程，主要特征是 β-淀粉样蛋白 (Aβ) 和过度磷酸化 MAPT 的沉积。这些积累破坏了最佳的神经元蛋白质稳态，因此，自噬的恢复/增强已被提议作为针对这些蛋白质病的治疗方法。本研究的目的是表征高度特化神经元中 MTORC1 和 AMPK 信号通路对自噬的调节，以及它们对 Aβ 产生的影响。使用 AD 的双转基因小鼠模型，我们证明了 MTORC1 抑制，无论是体内还是体外（原代神经元培养物），都能够通过神经元中的适度自噬诱导来减少淀粉样蛋白的分泌。神经元自噬的药理学预防增加了 Aβ 分泌并逆转了雷帕霉素的作用，证实了神经元自噬的抗淀粉样蛋白生成作用。用化合物 C 抑制 AMPK 产生了预期的自噬诱导减少，但令人惊讶的是并没有增加 Aβ 分泌。相比之下，二甲双胍、AICAR、2DG 或通过基因过表达增加的 AMPK 活性不会增强自噬，但对 Aβ 分泌有不同的影响：而二甲双胍和 2DG 减少了分泌的 Aβ 水平，AICAR 和 PRKAA1/AMPK 基因过表达增加了它们。我们得出结论，AMPK 在原代神经元中的作用与其他报道的细胞显着不同，对自噬依赖性淀粉样变性缺乏直接影响。缩写：2DG：2-脱氧-D-葡萄糖；Aβ：β-淀粉样蛋白；ACACA：乙酰辅酶A羧化酶α；ACTB：肌动蛋白β；AD：阿尔茨海默病；AICAR：5-氨基咪唑-4-甲酰胺-1-β-核糖苷；AKT：AKT 激酶组（AKT1 [AKT 丝氨酸/苏氨酸激酶 1]、AKT2 和 AKT3）；AMPK：腺苷 5'-单磷酸 (AMP) 活化蛋白激酶；APP：淀粉样β前体蛋白；APP/PSEN1：B6.Cg-Tg（APPSwe、PSEN1dE9）85Dbo/J；ATG：自噬相关；ATP：三磷酸腺苷；BafA1：巴弗洛霉素A1；CA：组成型活性；CGN：小脑颗粒神经元；CoC/化合物C：dorsommorphin二盐酸盐；ELISA：酶联免疫吸附测定；GAPDH：3-磷酸甘油醛脱氢酶；绿色荧光蛋白：绿色荧光蛋白；Gmax：GlutaMAX™；IN1：PIK3C3/VPS34-IN1；KI：激酶失活；MAP1LC3B/LC3：微管相关蛋白1轻链3；MAPT/TAU：微管相关蛋白 tau；Metf：二甲双胍；捷运：MRT68921；MTORC1：雷帕霉素激酶复合物 1 的机制靶点；NBR1：NBR1 自噬货物受体；PRKAA：5'-AMP 活化蛋白激酶催化亚基 α；PtdIns3K：磷脂酰肌醇3-激酶；Rapa：雷帕霉素；RPS6KB1/S6K：核糖体蛋白S6（RPS6）激酶多肽1；SCR：加扰；SQSTM1/p62：sequestosome 1；ULK1/2：unc-51 样自噬激活激酶 1/2；WT：野生型。雷帕霉素激酶复合物 1 的机制靶点；NBR1：NBR1 自噬货物受体；PRKAA：5'-AMP 活化蛋白激酶催化亚基 α；PtdIns3K：磷脂酰肌醇3-激酶；Rapa：雷帕霉素；RPS6KB1/S6K：核糖体蛋白S6（RPS6）激酶多肽1；SCR：加扰；SQSTM1/p62：sequestosome 1；ULK1/2：unc-51 样自噬激活激酶 1/2；WT：野生型。雷帕霉素激酶复合物 1 的机制靶点；NBR1：NBR1 自噬货物受体；PRKAA：5'-AMP 活化蛋白激酶催化亚基 α；PtdIns3K：磷脂酰肌醇3-激酶；Rapa：雷帕霉素；RPS6KB1/S6K：核糖体蛋白S6（RPS6）激酶多肽1；SCR：加扰；SQSTM1/p62：sequestosome 1；ULK1/2：unc-51 样自噬激活激酶 1/2；WT：野生型。