mTOR 途径抑制剂抗衰老的地点和方式: 雷帕霉素、白藜芦醇和二甲双胍

0 Comments

Where and How in the mTOR Pathway Inhibitors Fight Aging: Rapamycin, Resveratrol, and Metformin

Abstract

摘要

The molecular mechanisms underlying the quality and quantity of life extension appear to sometimes be orthogonal. For example, while resveratrol has continued to prove beneficial in reducing obesity, it has had less efficacy in extending lifespan. On the other hand, rapamycin and the chemically similar rapalogs extend lifespan across genera of life from yeast, to nematodes, to mice. Caloric restriction (CR) and bioavailable small molecules, which mimic a fasted state, upregulate autophagy, catabolism of fats over anabolism of carbohydrates, and decrease oxidative stress and inflammation. CR mimics are currently being investigated to elucidate the best dosage, route of administration, timing in life, where best to inhibit in the mTOR pathway, and effects of long-term use on mTORC1 verse mTORC2 complexes. Comparisons between rapamycin, resveratrol, and metformin targets, downstream pathway effects, dosage, and clinical trials will be discussed.

延长寿命的质量和数量的分子机制有时似乎是正交的。例如,虽然白藜芦醇在减少肥胖方面继续被证明是有益的,但在延长寿命方面却没有多少功效。另一方面,雷帕霉素和化学结构相似的雷帕霉素延长了酵母、线虫和小鼠等生物属的寿命。热量限制(CR)和生物可利用小分子,模拟禁食状态,上调自噬,分解代谢脂肪超过合成代谢的碳水化合物,并减少氧化应激和炎症。目前正在研究 CR 模拟物以阐明 mTORC1复合物的最佳剂量、给药途径、生命时间、 mTOR 通路中最佳抑制位置以及长期使用对 mTORC1复合物的影响。将讨论雷帕霉素、白藜芦醇和二甲双胍靶点、下游通路效应、剂量和临床试验之间的比较。

Keywords

关键词

  • rapamycin 雷帕霉素
  • rapalogs 猛禽
  • resveratrol 白藜芦醇
  • metformin 二甲双胍
  • mTOR
  • senescence 衰老
  • aging 老化
  • longevity 寿命
  • autophagy 自噬作用
  • inflammation 炎症

Chapter and author info

第一章及作者简介

Show + 展示 +

1. Introduction

1. 引言

It has been shown across the animal kingdom that caloric restriction (CR) extends lifespan. It is logistically harder to test this in longer living animals due to the length of studies needed, but there are studies in non-human primates [1] and ongoing human test groups who show fewer signs of cardiovascular aging [2]. Two trials calorically constricting macaques began in the 1980s and initially had conflicting results. A study out of University of Wisconsin found a drastic 30% increased survival in the CR group compared to control [3], while a latter study by the National Institute on aging (NIA) did not find a statistically relevant effect [4]. It was later found that in the NIA study, control monkeys consumed fewer calories than expected, and some in the CR groups began consuming reduced calories as juveniles, which is known to reduce lifespan. A reanalysis of all data by both groups agreed caloric restriction appears to increase macaque longevity by almost 10% (3 years in macaques which would translate to 9 years in humans) [1].

整个动物王国都表明,限制热量摄入(CR)可以延长寿命。由于所需的研究时间较长,在寿命较长的动物身上进行这项实验在逻辑上更加困难,但是在非人类灵长类动物身上进行的研究和正在进行的人类实验群体中,心血管衰老的迹象较少。20世纪80年代开始的两项试验,对恒河猴进行了热量收缩试验,最初的结果相互矛盾。威斯康星大学麦迪逊分校的一项研究发现,与对照组相比,CR 组的存活率大幅提高了30% ,而国家衰老研究所(NIA)的后一项研究没有发现有统计学相关性的影响。后来在 NIA 的研究中发现,对照组的猴子摄入的卡路里比预期的要少,而 CR 组的一些猴子在幼年时期就开始摄入减少的卡路里,众所周知,这会减少寿命。两个研究小组对所有数据进行了重新分析,一致认为限制热量似乎可以使猕猴的寿命延长近10% (猕猴的寿命为3年,人类的寿命为9年)。

In general results have seemed positive, extending life, but to a lesser degree than in small animal models, such as mice which have seen up to a 50% increase in lifespan from CR [5]. The search for pharmaceuticals to mimic CR life extension will need to continue the long and expensive process of large human studies due to humans’ unique interaction with calories in our post-industrial world. Study designs for larger caloric restriction studies are often questioned. Particularly concerning humans, the ability to accurately track caloric consumption in people living outside a clinical setting has often relied on caloric approximations such as food diaries, pictures of food eaten [678], or dietary consumption habits at a national level when comparing between countries. The larger percentage life extension effects from CR has been seen across many simpler organisms with budding yeast, fruit flies and worms having their lifespan increased 2–3 fold. However, no mammals have had such large effects. Indeed no one has suggested humans could achieve such great gains with CR which would extend our current upper lifespan from ~100 years to over 200 years. However, mammals such as rats and mice have shown a 20–50% reduction in calories can result in a lifespan increase of up to 50% [910].

总的来说,研究结果看起来是积极的,可以延长寿命,但是与小动物模型相比,其延长寿命的程度要小一些,比如小鼠的寿命由 CR [5]延长了50% 。由于后工业时代人类与卡路里的独特相互作用,模仿 CR 生命延长的药物研究将需要继续漫长而昂贵的大规模人体研究过程。大规模热量限制研究的设计经常受到质疑。特别是对于人类来说,在不同国家之间进行比较时,准确追踪生活在临床环境之外的人的热量消耗的能力往往依赖于热量近似值,如食物日记、食物摄入图片[6,7,8]或国家层面的饮食消耗习惯。来自 CR 的更大比例的延长寿命效应已经在许多简单的生物体中被发现,比如芽殖酵母、果蝇和蠕虫的寿命增加了2-3倍。然而,没有哺乳动物有这么大的影响。事实上,没有人认为人类可以通过 CR 获得如此巨大的收益,从而将我们目前的高寿命从100岁延长到超过200岁。然而,哺乳动物,比如大鼠和老鼠,已经显示出20-50% 的热量减少可以导致寿命增加50% [9,10]。

Even with these qualifiers in mind, it seems likely that a 30–60% reduction in calories could extend human life 10–20%. This gain of ~1% of lifetime for every ~3% reduction in calories translates to a likely ~10–20 years of extra life for humans, which is similar to the 9-year human equivalent life extension seen in the recent reanalysis of primates undergoing CR [1]. This 1:3 ratio of %lifetimeExtension:%caloricRestriction (LE:CR) may end up being 1:4 or 1:2 in humans, but in either scenario it is most likely caloric restriction will show a statistically significant life extension in humans. However, it is not likely to be a panacea that would give us 50 extra years bringing us past 150 years-of-age, despite that relative effect in mice.

即使考虑到这些限定条件,似乎30-60% 的卡路里减少可能会延长人类10-20% 的寿命。热量每减少3% ,寿命就增加1% ,这意味着人类可能多活10-20年,类似于最近重新分析灵长类动物经历 CR [1]时所看到的相当于人类寿命延长9年的情况。这个1:3% 的寿命延长率对人类来说可能是1:4或1:2,但是在任何一种情况下,热量限制都极有可能显示出人类寿命延长的统计学意义。然而,它不太可能是一个灵丹妙药,可以让我们多活50年,使我们超过150岁,尽管相对的影响

The current dilemma has been elucidating the root cause(s) responsible for life extension which are being targeted as pharmaceutical targets. The “inputs” that one might measure which lead to an increased lifespan in humans (e.g. obesity, cholesterol, cancer, bone density) are numerous and often orthogonal in nature. For example at pharmacological concentrations resveratrol does inhibit obesity but did not inhibit cellular senescence like rapamycin does [11]. While resveratrol and rapamycin were at times thought to act similarly, their mechanistic and pharmacological issues are diverging. While resveratrol had been found to extend life in studies there have been negative results with some labs failing to find life extension in all strains of yeast [12], worms, and flies [13]. Indeed rapamycin but not resveratrol has been shown to extend lifespan in mice [14]. Resveratrol may increase our quality of life while rapamycin (and rapalogs) could increase our quantity of life. In addition, one of resveratrol’s main issues is its bioavailability (it’s good we just want more), whereas rapamycin may shut down people’s immune system too much leading to cancer (it’s good but too much is bad). The mechanism of action for rapamycin, resveratrol, and metformin, as well as animal and human studies will be discussed.

目前的困境一直是阐明根本原因负责延长寿命的目标是药物目标。人们可能测量的导致人类寿命延长的“输入”(如肥胖、胆固醇、癌症、骨密度)数量众多,而且往往是正交的。例如,在药理浓度方面,白藜芦醇确实可以抑制肥胖,但不能像雷帕霉素那样抑制细胞衰老。虽然白藜芦醇和雷帕霉素有时被认为具有相似的作用,但它们的机制和药理学问题正在发生变化。虽然在研究中发现白藜芦醇可以延长寿命,但一些实验室未能在所有酵母菌、蠕虫和果蝇中找到延长寿命的方法。事实上,雷帕霉素而不是白藜芦醇已被证明可以延长小鼠的寿命[14]。白藜芦醇可以提高我们的生活质量,而雷帕霉素(和雷帕霉素)可以增加我们的生活质量。另外,白藜芦醇的主要问题之一是它的生物利用度(我们只是想要更多) ,而雷帕霉素可能过度关闭人体免疫系统导致癌症(雷帕霉素是好的,但过量则是坏的)。作用机制雷帕霉素,白藜芦醇,二甲双胍,以及动物和人类研究将进行讨论。

The ideal “biological scale” at which aging can be targeted is also still in question (a single gene, pathway, salvaging a cell, or killing unrecoverable cells) (Figure 1). Single genes continue to be investigated with inhibition by siRNA, conditional knockouts, or reducing posttranslational modifications such as lipid anchoring [15161718192021], while activation could be investigated via upregulation of transcription factors or viral therapy such as CRISPR. However, due to overlapping inputs the field often addresses how entire pathways are being affected (such as increased mitochondria biogenesis by caloric restriction). In addition while in vitro studies have often looked at modifying a cells genetic profile to have more of a centenarian profile (i.e. to rescue human cells via an intervention), it has recently been shown many cells become senescent and causing those to undergo apoptosis can save other cells thereby resulting in organism longevity [22232425262728]. The easiest abnormal aging targets may be the overactive cancerous cells we have become use to targeting via single genetic markers (e.g. targeting estrogen receptor sensitivity in breast cancer). Pathways can be targeted via some important individual targets, for example rescuing p53 deficiency or inhibiting mdm2 over activity to cause apoptosis. However rescuing cells from becoming senescent is the hardest and most distant task, required to truly push human longevity beyond a ~125 year limit (Figure 1). An important comparison is the case of the hydra which has been pointed to in the last couple of decades as an immortal multicellular organism [2930]. The hydra however, has a structure in which stem cells continually differentiate and move the periphery where they fluff off. There is not a large repository of persistent differentiated cells that can never become senescent for their hydra to continue living. In this regard the hydra can be thought of amputating any problem cells which it can replace [313233]. Many of humanity’s growing diseases involve multi-organ systems with terminally differentiated cells which cannot be easily replaced. For example, neurodegenerative diseases such as Alzheimer disease (AD) have phenotypic effects when neurons start dying in large numbers. While CR and CR mimics may increase autophagy and delay cell death, as discussed below, there is not evidence that inhibition of the mTOR pathway can perpetually shift humans as an organism to a hydra like state of immortality. Since 1932 the correlation between mass and metabolic rate for mammals has been investigated as a foundation for humans’ upper lifespan limit [3435]. It could be that the lower molecular activity from CR will shift humans to a longer lifespan following the three-quarters power law (or Kleiber’s Law), although more recent studies seem to be elucidating cellular and molecular minutia in a more fine-grained manner than Kleiber’s course mass does [363738].

理想的“生物尺度” ,其中可以老化的目标也仍然存在问题(一个单一的基因,路径,抢救细胞,或杀死不可恢复的细胞)(图1)。单个基因继续通过 siRNA 抑制、条件敲除或减少翻译后修饰(如脂质锚定[15,16,17,18,19,20,21])进行研究,而激活可以通过转录因子上调或病毒治疗(如 CRISPR)进行研究。然而,由于重叠的输入领域往往解决如何整个通路正在受到影响(如增加线粒体生物发生的热量限制)。此外,虽然体外研究经常着眼于修改细胞遗传图谱,使其具有更多的百岁老人的特征(即通过干预手段拯救人类细胞) ,但最近的研究表明,许多细胞衰老,导致细胞凋亡,可以拯救其他细胞,从而使有机体长寿[22,23,24,25,26,27,28]。最容易出现的异常衰老靶点可能是我们已经通过单一遗传标记(例如乳腺癌中的雌激素受体敏感性)来瞄准的过度活跃的癌细胞。途径可以通过一些重要的个体靶点来达到目的,例如挽救 p53缺陷或抑制 mdm2过度活性以引起细胞凋亡。然而,挽救衰老的细胞是最困难和最遥远的任务,需要真正推动人类寿命超过125年的限制(图1)。一个重要的比较是九头蛇的例子,在过去的几十年里,它被指出是不朽的多细胞生物。然而,水螅有一种结构,其中干细胞不断分化并移动其周围的毛发。没有一个持续分化的细胞的大型储存库,它们永远不会衰老,从而使水螅得以继续生存。在这方面,水螅可以被认为可以切除任何问题细胞,它可以取代[31,32,33]。许多人类发展中的疾病涉及多器官系统与终末分化的细胞,不容易取代。例如,当神经元大量死亡时,神经退行性疾病如阿兹海默病(AD)就会产生表型效应。虽然 CR 和 CR 模仿可能会增加细胞自噬并延缓细胞死亡,正如下面讨论的,没有证据表明抑制 mTOR 通路可以永久性地将人类作为一个有机体转变为水螅状态的永生。自1932年以来,研究哺乳动物的体重和代谢率之间的相关性已成为人类寿命上限的基础[34,35]。虽然最近的研究似乎比克莱伯的课程质量(36,37,38)更加细致地阐明了细胞和分子的细节,但是 CR 的低分子活性可能会使人类按照四分之三幂定律(即克莱伯定律)延长寿命。

Figure 1.图1Therapeutics for “aging” will likely having differing levels of complexity in their targets depending on if they are targeting a single gene (easiest), a pathway, cause death of senescent cells, or trying to salvage a cell from becoming senescent (most difficult). Overactive cancerous cells can be targeted simply to kill based on one receptor or gene, while salvaging neurons from death (e.g. various dementias) is a harder therapeutic task.针对“衰老”的治疗方法可能具有不同程度的目标复杂性,这取决于它们是针对单个基因(最简单的)、一条通路、导致衰老细胞死亡,还是试图挽救衰老细胞(最困难的)。过度活跃的癌细胞可以通过一个受体或基因来杀死,而从死亡中拯救神经元(例如各种痴呆症)则是一项更难的治疗任务。

2. mTOR pathways: rapamycin, resveratrol, and metformin

2. mTOR 途径: 雷帕霉素、白藜芦醇和二甲双胍

A wealth of studies has confirmed that rapamycin and rapalogs directly inhibit mTOR, whereas resveratrol’s targets are more numerous. Initially resveratrol was thought to act primarily through activation of sirtuins, with sirtuin-1 (SIRT1) known to help reduce obesity [39]. It is now known resveratrol also activates adenylyl cyclase and AMP-activated protein kinase (AMPK), while inhibiting a slew of proteins including lipoxygenase, protein kinase C (PKC), p53, mitogen-activated protein kinase 3 (MAPK3), proto-oncogene tyrosine-protein kinase (Src), signal transducer and activator of transcription 3 (STAT3), and IκB alpha kinase (IKK) [40]. One of the main targets is now AMPK activation which itself activates SIRT1 leading to mTOR inhibition.

大量的研究已经证实雷帕霉素和雷帕霉素可以直接抑制 mTOR,而白藜芦醇的作用靶点更多。最初认为白藜芦醇主要通过激活 sirtuins 起作用,而 sirtuin-1(SIRT1)已知可以帮助减少肥胖[39]。目前已知,白藜芦醇还能激活腺苷酸环化酶和 AMP活化蛋白激酶,同时抑制大量蛋白质,包括脂氧合酶、蛋白激酶C (PKC)、 p53、丝裂原活化蛋白激酶3(MAPK3)、原癌基因酪氨酸蛋白激酶(Src)、 STAT3(STAT3)和 iκbalpha 激酶(IKK)[40]。其中一个主要目标现在是 AMPK 激活,它本身激活 SIRT1导致 mTOR 抑制。

2.1. Anabolic vs. catabolic energy production

2.1. 合成代谢与分解代谢产生能量

AMPK is one of the primary metabolic detectors conserved across genera being activated by conditions that cause a low ATP:ADP ratio such as hypoglycemia and hypoxia. Phosphorylation of likely over 1000 targets by AMPK [41] shuts off anabolic pathways (energy-using) and turns on catabolic pathways (energy-generating). One of AMPKs targets for phosphorylation is peroxisome proliferators-activated receptor gamma coactivator-1 alpha (PGC-1α) which becomes active resulting in increased mitochondria biogenesis, membrane potential, and fatty acid oxidation [42], a recurring feature found during caloric restriction [4344]. AMPK also activates forkhead transcription factors of the O class (FOXO) which leads to increased autophagy and antioxidants, both leading to increased oxidative metabolism, like PGC-1α does [44].

腺苷酸活化蛋白激酶(AMPK)是在低血糖和缺氧等低 ATP: ADP 比值条件下激活的基因代谢探测器之一。磷酸化可能超过1000个目标由 AMPK [41]关闭合成代谢途径(能量使用)和打开分解代谢途径(能量产生)。Ampk 的磷酸化靶点之一是过氧化物酶体增殖物激活受体 γ 辅激活剂 -1α (pgc-1α) ,它变得活跃,导致线粒体生物合成、膜电位和脂肪酸氧化增加[42] ,这是在热量限制期间发现的一个反复出现的特征[43,44]。AMPK 还激活 o 类的叉头转录因子(FOXO) ,导致自噬和抗氧化剂的增加,两者都导致唿吸作用的增加,就像 pgc-1α 一样。

In the case of life extending interventions dosing becomes very important. Too much of a good thing, can definitely be bad (i.e. cancer), and the molecular mechanism effecting longevity are being elucidated. For example, in Caenorhabditis elegans, metformin is found to delay development under well-fed conditions and even reduces life span during starvation [454647]. The improved mitochondrial function, decreases oxygen consumption needed, which causes a beneficial decrease in reactive oxygen species (ROS) [4849]. Mitochondrial biogenesis is controlled differently depending on tissue and disease state. For example, mTOR signaling has been found to increase expression of mitochondrial genes involved in oxidative metabolism, through PGC-1α and Ying-Yang 1 (YY1). This increased mitochondrial biogenesis in the muscle of healthy individuals, but not in obese individuals perhaps due to decreased insulin sensitivity [50]. Not only is mTORC1 activity cell specific, but it is also concentration dependent being induced and inhibited by low and high levels of ROS respectively [51]. This concentration sensitivity of mTOR is beneficial since it acts as a hub for interdependent pathways, such as mTORs ability to modify both mitochondrial biogenesis and increase autophagy (which helps degrade damaged mitochondria and other organelles). Two models of aging have been established in yeast (Saccharomyces cerevisiae): replicative lifespan (RLS) and the chronological lifespan (CLS). RLS measures the number of asymmetric mitotic divisions a cell can undergo before cell cycle arrest and is a valuable model for fibroblasts, lymphocytes, or stem cells in humans [4525354]. CLS in contrast measures how long stationary (Go) cultures remain viable and is a model for postmitotic cells like neurons or muscle cells [525455]. Organ specific analysis of human in vivo studies, while difficult, would help elucidate CR mimics at and upstream of mTOR.

在延长生命的情况下,剂量变得非常重要。太多的好事,肯定会是坏事(比如癌症) ,而且影响长寿的分子机制正在被阐明。例如,在秀丽隐桿线虫,二甲双胍被发现在喂养良好的条件下延缓发育,甚至在饥饿时减少寿命[45,46,47]。线粒体功能的改善,减少了所需的氧气消耗,从而导致了有益的活性氧类(ROS)的减少。线粒体的生物发生受到不同组织和疾病状态的控制。例如,已经发现 mTOR 信号通过 pgc-1α 和 Ying-Yang 1(yyy1)增加与唿吸作用相关的线粒体基因的表达。这增加了健康个体肌肉中的线粒体生物合成,但不是肥胖个体,可能是由于胰岛素敏感性降低[50]。不仅 mTORC1活性细胞具有特异性,而且它还具有浓度依赖性,分别受到低水平和高水平 ROS 的诱导和抑制。mTOR 的这种浓度敏感性是有益的,因为它是相互依赖的通路的枢纽,例如 mTOR 能够修改线粒体的生物发生和增加自噬(这有助于降解受损的线粒体和其他细胞器)。在酵母中建立了两种衰老模型: 复制寿命模型(RLS)和时间序列寿命模型(CLS)。RLS 测量的是细胞在细胞周期停滞之前可以经历的不对称有丝分裂的数量,是人类成纤维细胞、淋巴细胞或干细胞的一个有价值的模型[4,52,53,54]。CLS 则用来衡量静止(Go)培养的存活时间,是神经元或肌肉细胞等有丝分裂后细胞的模型[52,54,55]。人体器官特异性分析的体内研究,虽然困难,将有助于阐明 CR 模拟在和上游的 mTOR。

Metformin is a third life extending compound worth contrasting to rapamycin and resveratrol because it inhibits the mitochondrial respiratory chain complex I, leading to decreased ATP:ADP, which activates AMPK [56]. In addition metformin has lots of human data since it is a common oral antidiabetic drug used for overweight people with type 2 diabetes mellitus (T2DM). Metformin inhibits hepatic glucose production, reduces insulin resistance, and has recently been investigated as anti-aging therapeutic. Metformin is currently being investigated for use in various cancers [5758]; however, metformin has also been linked to the development of some solid tumors in humans, namely colorectal, breast, and pancreas cancer [59]. Mitochondrial complex I is clearly inhibited by metformin leading to the AMPK dependent activation of TSC2 which inhibits mTOR. AMPK can also directly inactivate mTORC1 complex via phosphorylation of its subunit Raptor. However, it has also been shown that metformin can act in an AMPK independent manner, though that mechanism is less clear but could involve nuclear pore complex (NPC) or late endosome interactions which have been documented [46]. The NPC interaction was found when C. elegans ortholog of acyl-CoA dehydrogenase family member 10 (CeACAD10) knockdown was found to have a 3-fold resistance to metformin. CeACAD10 expression was more than doubled by 50 mM metformin, and an unbiased, forward genetic screen found the nuclear pore complex is required for metformin to induce CeACAD10 [47]. That molecular pathway is currently unique to metformin, compared to resveratrol or rapamycin, and while multiple targets have been found for metformin, some pathways overlapping between these three molecules allow a more robust understanding of caloric restrictions possible of life extension mechanisms. Not only mTORC1, but even upstream AMPK, has been shown to be required for the positive effects of all three molecules rapamycin [60], resveratrol [6162], and metformin [6364]. Metformin’s molecular pathway has also been elucidated upstream of AMPK. Metformin interacts with organelle Na1/H1 exchangers (eNHE) and the V-type-ATPase (V-ATPase) which supports the idea of the late endosome/lysosome, which is required by both the AMPK and mTOR pathway, acting as a signaling hub for metabolism [45].

二甲双胍是一种值得与雷帕霉素和白藜芦醇进行对比的延长寿命的化合物,因为它能抑制线粒体呼吸链复合物 i,导致 ATP: ADP 的减少,而 ADP 可激活 AMPK [56]。此外,二甲双胍有大量的人类数据,因为它是一种常见的口服降糖药物,用于治疗超重的 T2DM 2型糖尿病。二甲双胍抑制肝脏葡萄糖的产生,降低胰岛素抵抗,最近已被研究作为抗衰老治疗。二甲双胍目前正在研究用于各种癌症[57,58] ; 然而,二甲双胍也被认为与人类某些实体肿瘤的发展有关,即结肠直肠癌、乳腺癌和胰腺癌[59]。线粒体复合物 i 明显受到二甲双胍的抑制,导致 TSC2的 AMPK 依赖性激活,抑制 mTOR。AMPK 也可以通过磷酸化其 Raptor 亚单位直接灭活 mTORC1复合体。然而,也有研究表明二甲双胍可以以一种独立的 AMPK 方式发挥作用,尽管这种机制还不是很清楚,但是可能涉及到核孔或者内部体晚期相互作用,这些已经被记录在案[46]。当 acyl-CoA 脱氢酶家族成员10(CeACAD10)对二甲双胍具有3倍的抗性时,发现了线虫与 NPC 的相互作用。CeACAD10的表达量增加了一倍多,增加了50毫米二甲双胍的表达量,而且一个无偏见的正向遗传筛选发现,二甲双胍诱导 CeACAD10的核孔需要一个基因组。与白藜芦醇或雷帕霉素相比,二甲双胍目前的分子路径是独一无二的,虽然二甲双胍有多个靶点,但是这三个分子之间的某些路径重叠,使得对热量限制的可能延寿机制的理解更加健全。不仅 mTORC1,甚至 AMPK 的上游,已经被证明是所有三个分子雷帕霉素[60] ,白藜芦醇[61,62]和二甲双胍[63,64]的积极作用所必需的。二甲双胍的分子途径也已经阐明了 AMPK 的上游。二甲双胍与细胞器 Na1/H1交换器(eNHE)和 v 型 atp 酶(V-ATPase)相互作用,后者支持 AMPK 和 mTOR 途径所需的晚期内皮体/溶酶体的观点,作为新陈代谢的信号枢纽[45]。

While gross metrics such as weight are often reported in studies and useful to follow, they are not sufficient to investigate the aging phenomenon. For example, mice administered resveratrol have been found to not lose weight [6566]. The degree to which resveratrol mimics caloric restriction (CR) has been shown at a molecular level in mice with changes in gene expression overlapping in the adipose tissue, skeletal muscle, heart, liver, and neocortex. Interestingly, both resveratrol and CR slowed age-related decline in organ function, showing the benefit from resveratrol was not dependent on weight loss [6566]. The other side of the caloric coin which is frequently investigated independently of CR is exercise induced caloric deficit. In general CR has more robust life extension properties than an exercise induced caloric deficit. For modern humans it is clear it is extremely difficult to exercise one’s way into the same caloric deficit that can be attained through CR. In short, it is harder to run off a fast food meal than to not have the meal in the first place. It has been shown in rodents that increased activity to achieve a 30% relative energy deficit did not extend maximal lifespan but did increase average lifespan [967]. The ability of resveratrol to increase lifespan has varied significantly between studies, but been roughly 40% for yeast, 15% for worms, 30% for fish, and 10% for mice [68].

虽然研究中经常报告总体指标,如体重,并且可以遵循,但是它们不足以调查老化现象。例如,研究发现,服用白藜芦醇的小鼠并没有减肥效果[65,66]。白藜芦醇模拟热量限制(CR)的程度已经在分子水平上显示出来,小鼠的脂肪组织、骨骼肌、心脏、肝脏和新皮质的基因表达发生重叠。有趣的是,白藜芦醇和 CR 都减缓了年龄相关的器官功能衰退,表明白藜芦醇的益处不依赖于体重减轻[65,66]。热量硬币的另一面是运动诱导的热量缺乏,这是经常独立于 CR 进行调查的。一般来说,CR 比运动诱导的热量缺乏具有更强的延长寿命的特性。对于现代人来说,很明显,通过运动进入同样的能量消耗是极其困难的,这种能量消耗可以通过健康训练来达到。简而言之,吃完一顿快餐比不吃一顿饭要难得多。在啮齿类动物中已经发现,增加活动以达到30% 的相对能量赤字并不能延长最大寿命,但却能延长平均寿命[9,67]。白藜芦醇延长寿命的能力在不同的研究中有显著的差异,但是酵母菌大约40% ,蠕虫15% ,鱼类30% ,老鼠10% [68]。

There are two mTOR multisubunit protein complexes which have been shown to be differentially regulated. mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) share the protein components DEP domain containing mTOR-interacting protein (DEPTOR), mammalian lethal with sec-13 protein 8 (mLST8, also known as GβL), telomere maintenance 2 (telO2), and telO2-Interacting Protein 1 (tti1) (shown as light blue in Figure 2). mTORC1 has three core components: mTOR, regulatory-associated protein of mTOR (Raptor), and mammalian lethal with sec-13 protein 8 (mLST8). Whereas mTOR complex 2 (mTORC2) core components share mTOR, mLST8, but also include rapamycin-insensitive companion of TOR (Rictor), and mammalian stress-activated map kinase-interacting protein 1 (mSIN1) (Figure 2) [69]. mTORC1 is activated by nutrients and growth factors while being inhibited in low energy cellular states. A known complexity with the mTOR pathway is the difference in response to inhibitors, not only by mTORC1 and mTORC2, but also by tissue. mTORC1 is universally inhibited by rapamycin, whereas mTORC2 needs long term exposure to be inhibited by rapamycin which continues to be investigated. While DEPTOR is known to partially inhibit mTORC1 it may not decrease lipogenesis or inflammation alone, however in conjunction with AKT Serine/Threonine Kinase 1 (AKT) inhibitors can result in both decreases in lipogenesis and inflammation [70]. Combination therapy may be necessary in targeting mTORC1 to attained desired effects.

有两个 mTOR 多亚基蛋白复合体被证明是差异调控的。mTOR 复合体1(mTORC1)和 mTOR 复合体2(mTORC2)共享含有 mTOR- 相互作用蛋白(detor)的 DEP 结构域、哺乳动物与 sec-13蛋白8(mLST8,又称 GβL)的致死性、端粒维持2(telO2)和端粒-相互作用蛋白1(tti1)的蛋白成分(如图2所示为浅蓝色)。mTORC1有三个核心成分: mTOR、调节相关蛋白 mTOR (Raptor)和哺乳动物致死的 sec-13蛋白8(mLST8)。鉴于 mTOR 复合物2(mTORC2)的核心成分共享 mTOR,mLST8,但也包括雷帕霉素不敏感的 TOR (Rictor)伴侣,哺乳动物应激激活的地图激酶相互作用蛋白1(mSIN1)(图2)[69]。mTORC1被营养物质和生长因子激活,而在低能量细胞状态被抑制。mTORC1和 mTORC2以及组织对抑制剂反应的差异是 mTOR 通路的一个已知的复杂性。mTORC1普遍受到雷帕霉素的抑制,而 mTORC2需要长期暴露才能受到雷帕霉素的抑制。虽然已知 DEPTOR 部分抑制 mTORC1,但它可能不会单独减少脂肪形成或炎症,然而与 AKT 丝氨酸/苏氨酸激酶1(AKT)抑制剂联合使用可导致脂肪形成和炎症的减少[70]。在靶向 mTORC1达到预期效果时,联合治疗可能是必要的。

Figure 2.图2mTORC components, signaling, and inhibitors. Food, old age, and cancer activate PI3K and inactivation of AMPK which cause an increase mTOR activity in both complexes mTORC1 and mTORC2 and decrease the level of cellular autophagy. Autophagy can be restored through mTOR inhibitors (rapalogs, ATP-competitive inhibitors, Pan-mTOR inhibitors, dual PI3K/mTOR inhibitors) or reduced caloric intake (growth signals)‑all restore autophagy. Beneficial and deleterious interactions or macromolecules are shown in green and or dashed red respectively. Proteins found in both mTOR1 and mTOR2 are colored blue. Abbreviations: AMPK, AMP-activated protein kinase; DEPTOR, DEP domain containing mTOR-interacting protein; mLST8, mammalian lethal with sec-13 protein 8 (also known as GβL); mSin1, mammalian stress-activated map kinase-interacting protein 1; mTOR, mammalian target of rapamycin; mTORC, mammalian target of rapamycin complex; PRAS40, proline-rich Akt substrate 40 kDa; protor1/2, protein observed with rictor 1 and 2; RAPTOR, regulatory-associated protein of mammalian target of rapamycin; RICTOR, rapamycin-insensitive companion of mTOR; telO2, telomere maintenance 2; tti1, telO2-interacting protein 1.mTORC 成分、信号转导和抑制剂。食物、老年和癌症激活 PI3K 和 AMPK 失活,导致 mTORC1和 mTORC2复合物中 mTOR 活性增加,降低细胞自噬水平。通过 mTOR 抑制剂(rapalogs、 atp- 竞争性抑制剂、 pan-mTOR 抑制剂、双重 pi3k/mTOR 抑制剂)或减少热量摄入(生长信号)均可恢复自噬。有益和有害的相互作用或大分子分别用绿色和虚线红色显示。在 mTOR1和 mTOR2中发现的蛋白质是蓝色的。简称: AMPK,AMP活化蛋白激酶; DEPTOR,DEP 结构域,含有 mtor- 相互作用蛋白; mLST8,哺乳动物致死的 sec-13蛋白8(也称为 GβL) ;mSin1,哺乳动物应激激活蛋白激酶相互作用蛋白1; mTOR,雷帕霉素靶蛋白; mTORC,雷帕霉素复合物哺乳动物靶蛋白; PRAS40,富含脯氨酸的 Akt 底物40kda; protor1/2,雷帕霉素靶蛋白; RICTOR,雷帕霉素靶蛋白调节相关蛋白; RICTOR,雷帕霉素不敏感靶蛋白; telO2,端粒维持2; tti1,telO2-相互作用蛋白1。

While multiple targets upstream of mTOR continue to be investigated, well described downstream actions of mTOR help in analysis of in vivo, in vitro, and clinical studies. While the major downstream effect of mTOR activation is anabolic energy production (with inhibitors shifting to catabolic energy production from fat), another significant downstream effect of mTOR activation is increased inflammation. In general people living in the western world live in a state of excess inflammation. Time restricted feeding (TRF) was found to help immune response, reducing systemic low-grade inflammation and age-related chronic diseases linked to immunosenescence, without compromising muscle performance [71]. The reduced inflammation seen in calorically restricted individuals is partially due to an increase in autophagy from CR (see below). The mTOR pathway has been shown to trigger the development of T cells, B cells, and antigen-presenting cells (APC). Indeed resveratrol (found in plants such as grapes, red wine, mulberries, and peanuts) has been described as a broad spectrum of action anti-inflammatory which attenuates microglial cell overactivation through mTOR inhibition [72]. Resveratrol inhibition of NF-κB causes an increase in superoxide dismutase (SOD) and results in decreased proinflammatory cytokines IL-1β, IL-6, and TNF-α [73747576].

虽然 mTOR 上游的多个靶点仍在继续研究,但 mTOR 的下游作用有助于体内、体外和临床研究的分析。mTOR 激活的主要下游效应是合成代谢能量的产生(抑制剂从脂肪转移到分解代谢能量的产生) ,另一个重要的下游效应是炎症的增加。总的来说,生活在西方世界的人们生活在一种过度炎症的状态中。研究发现,限时喂养(TRF)有助于免疫反应,减少与免疫衰老有关的全身低度炎症和年龄相关的慢性疾病,而不影响肌肉功能[71]。在受热限制的个体中,炎症的减少部分是由于 CR 自噬的增加(见下文)。mTOR 通路已被证明可以触发 t 细胞、 b 细胞和抗原呈递细胞(APC)的发育。实际上,白藜芦醇(在植物中发现,如葡萄、红酒、桑葚和花生)被描述为一种广谱的抗炎作用,通过抑制 mTOR 来减弱小胶质细胞的过度活化[72]。白藜芦醇抑制核因子 -κb 引起超氧化物歧化酶增加,导致前炎症细胞因子 il-1β,IL-6和 tnf-α 降低[73,74,75,76]。

Genome wide analysis will likely be needed to elucidate the beneficial molecular level causes of caloric restriction. For example, Dato et al. recently analyzed pathway-based SNP-SNP interactions of 3 pathways: the insulin/insulin-like growth factor signaling (IIS), DNA repair, and pro/antioxidants. Synergistic effects on longevity were found in the combination of growth hormone secretagogue receptor (GHSR) and double strand break repair nuclease MRE11 homolog (MRE11A) genes which are involved in IIS signaling. TP53 also had synergistic effects with either ERCC Excision Repair 2 (ERCC2) or thioredoxin reductase 1 (TXNRD1). Those results highlighted the central role of TP53 in activating DNA repair and pro-antioxidant pathways [77].

全基因组分析可能需要阐明有益的分子水平的原因热量限制。例如,Dato 等人最近分析了胰岛素/胰岛素样生长因子信号传导(IIS)、 DNA 修复和前体/抗氧化剂3个途径的基于通路的 snp 相互作用。生长激素促分泌素受体(GHSR)和双链断裂修复核酸酶 MRE11同源基因(MRE11A)在 IIS 信号转导中发挥协同作用。TP53还与 ERCC 切除修复2(ERCC2)或硫氧还蛋白还原酶1(TXNRD1)有协同作用。这些结果强调了 TP53在激活 DNA 修复和促进抗氧化途径中的中心作用[77]。

2.2. Autophagy

2.2. 自噬

One pathway difference between rapamycin and resveratrol is the large magnitude with which rapamycin increases autophagy over apoptosis, which helps in regards to life extension but could prove problematic in cancer use. Pharmacological levels of resveratrol on the other hand prevent upregulation of Akt activation and autophagy thereby causing apoptosis. Resveratrol does inhibit obesity at pharmacological concentrations, prevent heightened hyperinsulinemia, or inhibit mTOR in vitro and therefore did not inhibit cellular senescence like rapamycin does [11]. Large levels of resveratrol have recently been shown to induce autophagy when inhibiting mTOR directly through ATP competition [78]. Combination therapy of rapamycin and resveratrol has proven synergistic in treatment of breast cancer cells [7980].

雷帕霉素和白藜芦醇之间的一个途径差异是雷帕霉素增加细胞自噬而不是细胞凋亡,这有助于延长寿命,但在癌症使用中可能会出现问题。另一方面,白藜芦醇的药理作用可以防止 Akt 激活和自噬的上调从而导致细胞凋亡。白藜芦醇在药理浓度上确实抑制肥胖,预防高胰岛素血症,或在体外抑制 mTOR,因此不像雷帕霉素那样抑制细胞衰老[11]。最近有研究表明,大剂量的白藜芦醇通过 ATP 竞争直接抑制 mTOR 时可诱导自噬。雷帕霉素和白藜芦醇联合治疗已被证明对乳腺癌细胞具有协同作用[79,80]。

Caloric restriction has been shown to increase autophagy through inhibition of mTOR and delay molecular events associated with dementia. The rise in neurodegenerative diseases, which are exacerbated by low autophagy levels, heightens interest in mTOR inhibitors. Caloric restriction achieves mTOR inhibition through two pathways: decreased PI3K activity and increased AMPK activity (Figure 2). Cells in low energy states (calorically restricted) have low PI3K activity, lowering Akt activity, which then lowers mTORC1 via inhibition by Tsc1/2 (Figure 3). Rapamycin directly inhibits mTOR but metformin and resveratrol inhibit mTOR through upstream pathways, inhibiting the mitochondrial complex I activity and increasing AMPK respectively. In the well fed state mTORC1 inhibits autophagy via inhibition of SIRT1, Unc-51 like autophagy activating kinase (ULK1), transcription factor EB/E3 (TFEB/TFE3). Active mTOR also stimulates eukaryotic translation though phosphorylation and inhibition of 4E-BP1 which in turn releases the bound cap-binding eukaryotic translation initiation factor 4E (eif-4E). When eif-4E is released it can participate in forming the eIF4F complex required for initiation of cap-dependent translation. Ribosomal proteins S6 and S6K are also stimulated by mTOR which leads to increased protein synthesis and lipogenesis. In the fasted state ULK1 starts autophagosome maturation and TFEB/TFE3 increases lysosomal biogenesis and autophagy. Ras-related GTPases (Rags) actually tether mTORC1 to the lysosomal surface and that connection is controlled through amino acid sensing of the vacuolar H+-adenosine triphosphatase ATPase (v-ATPase) as well as the proton-assisted amino acid transporter 1 (PAT1) (Figure 3). SIRT1 is also activated in the fasted state, and by CR mimetics, which increases SOD, p53, and activates FOXO leading to increases in cellular autophagy and mitochondrial biogenesis (Figure 2).

热量限制通过抑制 mTOR 和延缓与痴呆症相关的分子事件来增加自噬。低自噬水平加剧了神经退行性疾病的发生,提高了人们对 mTOR 抑制剂的兴趣。热量限制通过两个途径实现 mTOR 抑制: 减少 PI3K 活性和增加 AMPK 活性(图2)。在低能量状态(热量限制)的细胞有低 PI3K 活性,降低 Akt 活性,然后通过 Tsc1/2抑制 mTORC1(图3)。雷帕霉素通过上游途径直接抑制 mTOR,而二甲双胍和白藜芦醇通过上游途径抑制 mTOR,分别抑制线粒体复合物 i 活性和增加 AMPK。mTORC1通过抑制 SIRT1、类似自噬激活激酶(ULK1)的 Unc-51、转录因子 EB/E3(TFEB/TFE3)抑制自噬。活性 mTOR 通过磷酸化和抑制4E-BP1刺激真核翻译,4E-BP1反过来释放结合帽结合真核起始因子4E (eif-4E)。当 eif-4E 被释放时,它可以参与形成 eIF4F 复合物,这是启动依赖于上限的翻译所必需的。核糖体蛋白 S6和 S6K 也受到 mTOR 的刺激,导致蛋白质合成和脂肪生成的增加。在禁食状态下,ULK1开始自噬体成熟,TFEB/TFE3增加溶酶体的生成和自噬。Ras 相关的 GTPases (Rags)实际上将 mTORC1绑在溶酶体表面,这种连接通过对液泡 h +-ATP酶 atp 酶(v-ATPase)以及质子辅助的氨基酸转运蛋白1(PAT1)的氨基酸感应来控制。在禁食状态下,SIRT1也被 CR 模拟剂激活,增加 SOD,p53,激活 FOXO 导致细胞自噬和线粒体生物发生的增加(图2)。

Figure 3.图3mTOR pathway activation, inhibitors, and downstream effects. The molecular pathways increased by caloric restriction that increase lifespan are also targeted by rapamycin, resveratrol, and metformin. Metformin and resveratrol inhibit mTOR through upstream pathways, inhibiting the mitochondrial complex I activity and increasing AMPK respectively. Rapamycin, and rapalogs, on the other hand inhibit mTOR directly. Beneficial downstream effects of mTOR inhibition include increase mitochondrial function and biogenesis, lysosomal biogenesis, autophagy, and decreased translation. Deleterious effects of an active mTOR pathway include increased lipogenesis and inflammation. Beneficial and deleterious interactions or macromolecules are shown in green and or dashed red respectively. Abbreviations: AMP, adenosine monophosphate; AMPK, AMP-activated protein kinase; mTOR, mammalian target of rapamycin; SOD, superoxide dismutase; PGC-1𝛂, peroxisome proliferators-activated receptor gamma coactivator-1 alpha; IR, insulin receptor; RTK, receptor tyrosine kinase; Ras; MAPKKK, mitogen-activated protein kinase kinase kinase; MAPKK, mitogen-activated protein kinase kinase; MAPK, mitogen-activated protein kinase; PI3K; Akt = AKT Serine/Threonine Kinase 1; S6, ribosomal protein S6; S6K, ribosomal protein S6 kinase beta-1; 4E-BP1, eukaryotic translation initiation factor 4E-binding protein 1; eif-4E, eukaryotic translation initiation factor 4E; SREBP1/2, sterol regulatory element-binding protein; Rheb/Rhes; Tsc1/2, tuberous sclerosis proteins; PAT1, proton-assisted amino acid transporter 1; V-ATPase, vacuolar H+-adenosine triphosphatase ATPase; RAGs, Ras-related GTPases; ULK1, Unc-51 like autophagy activating kinase; TFEB/TFE3, transcription factor EB/E3. Ras, Ras superfamily (RAt Sarcoma); PI3K, Phosphoinositide 3-Kinase Gamma; Rheb, Ras homologue enriched in brain; Rhes, Ras homolog enriched in striatum.mTOR 途径激活,抑制剂和下游效应。通过热量限制提高寿命的分子途径也是雷帕霉素、白藜芦醇和二甲双胍的目标。二甲双胍和白藜芦醇通过上游途径抑制 mTOR,分别抑制线粒体复合物 i 活性和提高 AMPK 活性。雷帕霉素和雷帕霉素则直接抑制 mTOR。抑制 mTOR 的有利下游效应包括增加线粒体功能和生物发生、溶酶体生物发生、自噬和减少翻译。活性 mTOR 通路的有害影响包括增加脂肪生成和炎症。有益和有害的相互作用或大分子分别用绿色和虚线红色显示。简称: AMP,单磷酸腺苷; AMPK,AMP活化蛋白激酶; mTOR,雷帕霉素哺乳动物靶标; SOD,超氧化物歧化酶; pgc-1α,过氧化物酶体增殖物激活受体 γ 辅激活因子 -1α; IR,胰岛素受体; RTK,受体酪氨酸激酶; Ras;MAPKKK,有丝分裂原活化蛋白激酶激酶; MAPKK,有丝分裂原活化蛋白激酶激酶; MAPK,有丝分裂原活化蛋白激酶; PI3K; AKT = AKT 丝氨酸/苏氨酸激酶1; s 6,核糖体蛋白质 S6;S6K,核糖体蛋白质 S6激酶 beta-1; 4E-BP1,真核翻译起始因子4e 结合蛋白1; eif-4E,真核起始因子4E; SREBP1/2,甾醇调节元件结合蛋白; Rheb/Rhes; Tsc1/2,结节性硬化症蛋白; PAT1,质子辅助氨基酸转运蛋白1; V-ATPase,液泡 h +-ATP酶;RAGs,ras 相关的 GTPases; ULK1,Unc-51喜欢自噬激活激酶; TFEB/TFE3,转录因子 EB/E3。Ras,Ras 超家族(鼠肉瘤) ; PI3K,磷酸肌醇3- 激酶 γ; Rheb,Ras 同系物富集于大脑; Rhes,Ras 同系物富集于纹状体。

Therapeutics to help extend human lifespan far past the ~100 year limit will likely need to increase autophagy to avoid dementias, a later life disease state. With various dementias (PD, ALS, HD, and AD) having mitochondrial dysfunction [81828384], and mTOR activation known to increase oxidative stress, antioxidant therapies are being investigated. It has been found conjugating a cation compound to the antioxidant increases uptake into the mitochondria 80-fold and potency up to 800-fold [85] due to its 165 mV negative potential [86]. Low levels of autophagy also result in necrosis instead of apoptosis, with the resulting ramped up immune system increasing inflammation. Intracellular stress acts through Bcl-2 to open the mitochondrial permeability transition pore (mPTP) leading to caspase dependent intrinsic apoptosis [698788]. The mPTP is known to exist in 3 states: closed, transiently open in low conductance, and permanently open in high conductance [899091], the latter resulting in mitochondrial depolarization, loss of ATP production, and caspase independent necrosis since the controlled apoptotic pathway requires energy [92]. Multiple types of cancer show increased mTOR pathway signaling which is what the first mTOR inhibitors were FDA approved for: sirolimus, everolimus (Afinitor), temsirolimus (Torisel), and ridaforolimus, with sirolimus and everolimus also finding use as immunosuppressants after organ transplants [93].

有助于延长人类寿命的治疗方法远远超过100年的限制,可能需要增加自噬以避免痴呆,一种晚期疾病状态。随着各种痴呆症(PD,ALS,HD,和 AD)有线粒体功能障碍[81,82,83,84]和 mTOR 激活已知的增加氧化应激,抗氧化治疗正在研究。它已被发现与一个阳离子化合物结合到抗氧化剂增加摄取到线粒体80倍和效力高达800倍[85] ,由于其165 mV 负电位[86]。低水平的自噬也会导致坏死而不是细胞凋亡,从而增强免疫系统,增加炎症。细胞内应激通过 Bcl-2作用打开线粒体通透性转换孔(mPTP) ,导致 caspase 依赖性内源性凋亡[69,87,88]。mPTP 存在于3种状态: 低电导时闭合,瞬间开放,高电导时永久开放,后者导致线粒体去极化,ATP 产生减少,并且由于受控的凋亡途径需要能量[92]。多种类型的癌症显示 mTOR 信号通路增强,这是第一个 mTOR 抑制剂 FDA 批准的: 西罗莫司,依维莫司(Afinitor) ,替米莫司(Torisel) ,利达莫司,西罗莫司和依维莫司也发现用作器官移植后的免疫抑制剂[93]。

While caloric mimics will the not be the panacea pushing human life past 200 years it should be pointed out the large effect it could have in humans compared to other currently measurable lifestyle interventions. The effect was recently quantified for the top five frequent lifestyle interventions: smoking cessation, physical activity, healthy diet, healthy BMI, and low alcohol consumption (Table 1) [94]. Starting at age 50 women and men were found to be able to add on average 14 and 12 years respectively, if all 5 healthy lifestyles were adopted. Never smoking was the strongest healthy habit of the five, with a close second being engaging in physical activity over 30 min a day (which included brisk walking or anything more strenuous). The healthy diet and BMI (18–25 kg/m2) can both clearly be linked to a CR lifestyle. It will be interesting to compare the magnitude of CR life extension to the years gained by aspects of a “healthy diet” which is usually cataloged by many more variables than just caloric count (e.g. vitamin/antioxidants, omega-3 vs. omega-6 vs. saturated fat content). In summary, CR alone seems likely to have as big, or slightly larger, of an effect than the 5 healthy lifestyles in concert. If rapamycin, resveratrol, metformin, or a combination thereof, prove capable of reproducing even half the years of life extension that CR extension can, it would be a multi-billion dollar market (USD) and could be among the best therapeutics measured on the Quality Adjusted Life Years (QALY) scale.

虽然热量模拟将不是推动人类寿命超过200年的灵丹妙药,但应该指出的是,与其他目前可衡量的生活方式干预相比,热量模拟对人类可能产生的巨大影响。这种影响最近被量化为5个最常见的生活方式干预: 戒烟,身体活动,健康饮食,健康的身体质量指数,低酒精消耗量。如果五种健康的生活方式都被采用,那么从50岁开始,女性和男性的平均寿命分别增加了14岁和12岁。从不吸烟是这五个人中最强烈的健康习惯,其次是每天进行超过30分钟的体育活动(包括快走或任何更剧烈的运动)。健康的饮食和身体质量指数(18-25公斤/平方米)都与 CR 的生活方式有明显的联系。将 CR 寿命延长的幅度与“健康饮食”的各个方面所获得的寿命进行比较将是有趣的,因为“健康饮食”通常不仅仅是由热量计数(例如维生素/抗氧化剂、 omega-3 vs. omega-6 vs. 饱和脂肪酸含量)来分类。总而言之,单独的健康生活方式似乎比五种健康生活方式协调起来的影响更大,或者稍大一点。如果雷帕霉素、白藜芦醇、二甲双胍或者它们的组合能够复制出 CR 延长寿命一半的药物,这将是一个数十亿美元的市场(USD) ,并且可以成为质量调整生命年(QALY)量表中最好的治疗药物之一。

Lifestyle 生活方式
Physical activity (≥30 min/day) 体力活动(≥30分钟/天)87
Not smoking 不吸烟912
Healthy diet 健康饮食54
Low alcohol (15♀, 30♂ g/d = 2♀, 4♂ drinks/d) 低酒精(15♀ ,30♂ g/d = 2♀ ,4♂饮水/d)32
BMI (18–25 kg/m 体重指数(18-25公斤/米2)45
Extra years if all 5 如果所有的5年都是额外的几年1412

Table 1.

表一

Five healthy lifestyles that extend lifespan more than 10 years.

5种健康的生活方式可以延长寿命超过10年。

Five healthy lifestyles (exercise, healthy diet, ideal BMI, low alcohol, and not smoking) were found to add 12–14 years of life starting at age 50 when compared to people that did not follow any of the five lifestyles. The healthiest and worst habits within each lifestyle had very different life expectancies as well, with nonsmokers and excessive smokers having the largest lifespan gap (9–12 years). The second greatest gain in lifespan (7–8 years) came from getting more than 30 min of exercise a day compared to never exercising. Data from [94].

研究发现,五种健康的生活方式(运动、健康饮食、理想的体重指数、低酒精和不吸烟)与没有遵循这五种生活方式中任何一种的人相比,从50岁开始延长了12-14年的寿命。每种生活方式中最健康的和最糟糕的习惯也有着非常不同的预期寿命,不吸烟者和过度吸烟者的寿命差距最大(9-12年)。寿命的第二大增长(7-8年)来自于每天锻炼超过30分钟,而不是从不锻炼。数据来自[94]。

3. Preclinical and clinical studies

3. 临床前和临床研究

While there are chemically similar caloric restriction (CR) mimetics such as rapalogs for rapamycin, the main compounds discussed: resveratrol, rapamycin, and metformin are chemically distinct. Both resveratrol and metformin are hydrogen-donor rich, having hydroxyls and amides, respectively. Rapamycin is a much larger macrocycle molecule (MW = 914) with both hydrogen donor and acceptor moieties compared to the smaller resveratrol (MW = 228) and rapamycin (MW = 129) (Figure 4). Future docking, crystallography, and NMR studies would be interesting to determine if other molecules could mimic ATP, directly binding to the ATP pocket on mTOR as it has been suggested resveratrol does [78]. A structural mimic of ATP acting as an antagonist can seem conceptually attractive and likely have broad effects on multiple energy sensing proteins, but would also likely have lower than desired specificity.

虽然有化学类似的热量限制(CR)模型,如雷帕霉素的雷帕霉素,主要化合物讨论: 白藜芦醇,雷帕霉素和二甲双胍是化学不同的。白藜芦醇和二甲双胍都富含氢供体,分别含有羟基和酰胺。雷帕霉素是一种较大的高环分子(MW = 914) ,具有给氢和受氢两种基团,相比较较小的白藜芦醇(MW = 228)和雷帕霉素(MW = 129)(图4)。未来的对接、结晶学和 NMR 研究将有趣地确定其他分子是否可以模拟 ATP,直接结合到 mTOR 上的 ATP 口袋,因为有人认为白藜芦醇可以做到这一点[78]。模仿 ATP 作为一种拮抗剂的结构似乎在概念上很有吸引力,可能对多种能量感应蛋白质有广泛的影响,但也可能具有低于预期的特异性。

Figure 4.图4Structures of metabolism modifiers. The structures of compounds discussed: resveratrol, metformin, rapamycin, and ATP. Some have had suggested competitive binding pockets, such as resveratrol and ATP. However on a small molecule scale metformin, resveratrol, and rapamycin have very different complexity and differ by orders of magnitude in molecular weight. All compounds do have significant number of polar groups for hydrogen binding to protein surfaces and pockets.代谢调节剂的结构。讨论了化合物的结构: 白藜芦醇、二甲双胍、雷帕霉素和 ATP。有些人建议使用竞争性的束缚袋,如白藜芦醇和 ATP。然而在小分子尺度上,二甲双胍、白藜芦醇和雷帕霉素的复杂性有很大的不同,分子量也有很大的数量级。所有的化合物都有相当数量的极性基团,以便与蛋白质表面和囊袋结合。

All three compounds resveratrol, rapamycin, and metformin have had numerous human clinical trials. Metformin is unique among the three in that it is currently an approved and recommended therapy for a massive population, specifically obese individuals with type II diabetes, and therefore has a much larger dataset of patients to pull safety and efficacy information from. Resveratrol and rapamycin are both natural compounds with a plethora of academic papers in animal models, but rapamycin studies have the added nuance/diversity of involving a host of rapalogs with modified activity. A search of clinical trials including the keywords resveratrol, metformin and rapamycin and grouped by topic is shown inTable 2 (as of April 11th 2018). Resveratrol has the lowest number of ongoing clinical trials (137), metformin has over 2.5 fold as many (359), and rapamycin has almost fivefold ongoing clinical trials (646). Resveratrol and metformin have largely overlapping pathway targets in clinical trials with the most common being endocrine system diseases, diabetes mellitus, obesity, and insulin resistance. The main topics for rapamycin are neoplasms by histological type, vascular disease, and myocardial ischemia. Metformin and rapamycin have some overlap, e.g. metformin has 45 current trials listed under neoplasms by histological type, and rapamycin has 42 trials listed under endocrine system diseases.

这三种化合物白藜芦醇、雷帕霉素和二甲双胍已经进行了大量的人体临床试验。二甲双胍在这三种药物中是独一无二的,因为它目前被批准并推荐用于大规模人群,特别是肥胖的 II 型糖尿病患者,因此它拥有更大的患者数据集,可以从中提取安全性和有效性的信息。白藜芦醇和雷帕霉素都是天然化合物,在动物模型中有大量的学术论文,但雷帕霉素研究有着细微的差别,涉及到许多雷帕霉素的修饰活性。表2(截至2018年4月11日)显示了包括白藜芦醇、二甲双胍和雷帕霉素等关键词并按主题分组的临床试验的搜索结果。白藜芦醇在正在进行的临床试验中数量最少(137个) ,二甲双胍的数量超过2.5倍(359个) ,雷帕霉素几乎有5倍正在进行的临床试验(646个)。在临床试验中,白藜芦醇和二甲双胍有很大程度上重叠的通路靶点,最常见的是内分泌系统、糖尿病、肥胖和胰岛素抵抗。雷帕霉素的主要课题是组织类型、血管疾病和冠状动脉疾病。二甲双胍和雷帕霉素有一些重叠,例如二甲双胍目前有45项试验列在组织学类型的肿瘤之下,雷帕霉素有42项试验列在内分泌系统疾病之下。

Compound term search at 复合词搜索clinicaltrials.gov# CT ongoing # CT 正在进行中Insulin resistance 胰岛素抵抗Diabetes mellitus糖尿病Endocrine system diseases 内分泌系统疾病Obesity肥胖Neoplasms by histologic type 按组织学类型分类的肿瘤Vascular diseases血管疾病Myocardial ischemia 冠状动脉疾病
Resveratrol 白藜芦醇13728242319561
Metformin 二甲双胍359341781953445145
Rapamycin 雷帕霉素646112422218172143

Table 2.

表二

Ongoing clinical trials for resveratrol, rapamycin, or metformin (April 11th 2018 search of clinicaltrials.gov).

正在进行的白藜芦醇、雷帕霉素或二甲双胍的临床试验(2018年4月11日对 clinicaltrials.gov 的搜索)。

Clinical trials that are ongoing, as of April 11th 2018, were searched for the keywords resveratrol, metformin, and rapamycin. Resveratrol and metformin had overlapping metabolic clinical targets listed, while rapamycin had more numerous trials, which were focused on vascular diseases and cancer.

2018年4月11日,正在进行的临床试验搜索了白藜芦醇、二甲双胍和雷帕霉素的关键词。白藜芦醇和二甲双胍有重叠的代谢临床靶点列出,而雷帕霉素有更多的试验,这些试验集中在血管疾病和癌症。

4. Conclusions

4. 结论

The use of therapeutics that mimic caloric restriction (CR) is likely to increase and add incremental quality-adjusted life years (QALYs). Natural CR compounds, and analogs based off of them, are fairly cheap with low side effects. Controlled animal studies will likely continue to be the avenue which exposes the degree to which molecular pathways are responsible for the increased quality and quantity of life. Resveratrol and metformin seem robust at increasing molecular pathways linked to quality of health and are useful to combat obesity and type II diabetes; while their ability to increase maximum lifespan remains in question. Data suggests rapamycin and the follow on rapalogs could add years to a human lifespan, although the magnitude of the effect could be enhanced or completely ablated based on accompanying lifestyle choices (diet, exercise, sleep).

使用模拟热量限制(CR)的疗法可能会增加并增加质量调整生命年(QALYs)。天然 CR 化合物及其衍生物价格低廉,副作用小。受控动物研究很可能将继续成为暴露分子途径对生命质量和数量的提高负责的程度的途径。白藜芦醇和二甲双胍似乎在增加与健康质量相关的分子途径方面表现强劲,有助于对抗肥胖和 II 型糖尿病; 而它们延长最大寿命的能力仍然存在疑问。数据表明,雷帕霉素和后续的雷帕霉素可以延长人类的寿命,尽管这种影响的程度可以根据伴随的生活方式选择(饮食、锻炼、睡眠)而加强或完全消失。

Research shedding light on the optimum dosing of caloric mimics should be interesting to follow. Caloric restriction studies in humans fall into three categories: continual modest decrease in calories consumed (~1500 kcal/day), temporary drastic reduction in energy intake (~500 kcal/day), or intermittent fasting (0 kcal/day) in which only water is consumed for 1–3 days. Intermittent fasting has actually slightly outperformed all other methods of dieting methods (atkins, zone, weight watchers, ornish/vegan) in reducing weight in humans, which is partially due to increased compliance [9596]. The degree to which molecular pathway changes from intermittent fasting are responsible for reduced weight, such as increased autophagy, remains to be determined. The number of calories that can be consumed above complete fasting, while still increasing autophagy and decreasing inflammation, needs further investigation [11044979899100101102103104105106107108].

研究表明模拟热量的最佳剂量应该是有趣的后续行动。对人类进行的热量限制研究分为三类: 热量摄入持续适度减少(每天约1500千卡)、能量摄入暂时急剧减少(每天约500千卡) ,或间歇性禁食(每天只饮水1-3天)。实际上,间歇性禁食在减轻人类体重方面比其他所有节食方法(阿特金斯、阿特金斯、体重观察者、欧尼斯/纯素食主义者)略有优势,这在一定程度上是由于遵从性的提高[95,96]。间歇性禁食导致体重减轻的分子途径变化的程度,如增加的自噬,仍有待确定。在完全禁食后仍能增加自噬和减少炎症的情况下,能够摄入的卡路里数量需要进一步研究[1,10,44,97,98,99,100,101,102,103,104,105,106,107,108]。

5. Recommendations

5. 建议

It would be very useful for clinicians and patients to have a curve in which the x-axis showed calories consumed per day and the y-axis showed %change in these important life extension pathways (e.g. autophagy, inflammation, lipogenesis, lysosomal biogenesis, and protein synthesis). These studies/curves would ideally be done separately for various groups (e.g. males, females, diabetics, elderly predementia, and elderly with early dementia). The interaction of therapeutics that mimic CR in combination with a changing intake of calories from fluctuating diet will require significant large studies and clear simplifications for clinicians and patients to utilize that information and make actionable in daily life. The actionable timeline for CR mimics is still being investigated, but if studies from intermittent fasting apply then administration for months could be useful but lifetime use will be needed to maximize benefits.

对于临床医生和患者来说,有一条曲线是非常有用的,其中 x 轴显示每天消耗的卡路里,y 轴显示这些重要的生命延长途径(如自噬、炎症、脂肪生成、溶酶体生成和蛋白质合成)的% 变化。这些研究/曲线最好分别针对不同的人群(例如男性、女性、糖尿病患者、老年前期痴呆症患者和早期痴呆症患者)。模拟 CR 的治疗方法与变化饮食中卡路里摄入量的相互作用,需要对临床医生和患者进行大量的研究和明确的简化,以利用这些信息,并使之在日常生活中可行。模仿 CR 的行动时间表仍在调查中,但是如果间歇性禁食的研究适用,那么连续几个月的服用可能是有用的,但是为了最大限度地发挥效益,还需要终生服用。

Abbreviations

缩写

4E-BP1eukaryotic translation initiation factor 4E-binding protein 1 真核翻译起始因子4e 结合蛋白1
AD 广告Alzheimer disease 阿兹海默病
ALS 肌萎缩侧索硬化症amyotrophic lateral sclerosis 肌萎缩性嵴髓侧索硬化症
AKT 美国科学技术协会AKT Serine/Threonine Kinase 1 AKT 丝氨酸/苏氨酸激酶1
AMPKAMP-activated protein kinase AMP活化蛋白激酶
APC 平板电脑antigen-presenting cells 抗原提呈细胞
CeACAD10C. elegans ortholog of acyl-CoA dehydrogenase family member 10 线虫酰辅酶 a 脱氢酶家族成员10
CLS 美国海军陆战队chronological life span 实际寿命
CR 电阻抗caloric restriction 热量限制
DEPTOR 深海探测器DEP domain containing mTOR-interacting protein 含 mtor- 相互作用蛋白的 DEP 结构域
eif-4Eeukaryotic translation initiation factor 4E 真核起始因子4E
eNHENa1/H1 exchangers Na1/H1交换器
ERCC2ERCC Excision Repair 2 (ERCC2) ERCC 切除修复2(ERCC2)
FOXOforkhead transcription factors of the O class O 类叉头转录因子
GHSR 全球温室气体排放量growth hormone secretagogue receptor 生长激素促分泌受体
HD 房屋署Huntington disease 亨丁顿舞蹈症
IIS 国际信息系统insulin/insulin-like growth factor signaling 胰岛素/胰岛素样生长因子信号传导
IKKIκB alpha kinase IκB α 激酶
MAPK3mitogen-activated protein kinase 3 丝裂原活化蛋白激酶3
mLST8mammalian lethal with sec-13 protein 8 哺乳动物具有 sec-13蛋白8的致死性
mPTPmitochondrial permeability transition pore 线粒体通透性转换孔
MRE11Adouble strand break repair nuclease MRE11 双链断裂修复核酸酶 MRE11
mSIN1mammalian stress-activated map kinase-interacting protein 1 哺乳动物应激激活蛋白激酶相互作用蛋白1
mTORC1mTOR complex 1 mTOR 复合物1
mTORC2mTOR complex 2 mTOR 复合体2
NIA 女名女子名National Institute on aging 国家老龄化研究所
NPC 全国人大nuclear pore complex 核孔
PAT1proton-assisted amino acid transporter 1 质子辅助氨基酸转运蛋白1
PD 帕金森病Parkinson disease 帕金森氏症
PGC-1αproliferators-activated receptor gamma coactivator-1 alpha 增殖物激活受体 γ 辅激活因子 -1α
PKC 蛋白激酶 cprotein kinase C 蛋白激酶C
QALY 女名女子名Quality Adjusted Life Years 质素调整生命年
Rags 破布Ras-related GTPases 与 ras 有关的 GTPases
Raptor 猛禽regulatory-associated protein of mTOR mTOR 调节相关蛋白
Rictor 女名女子名rapamycin-insensitive companion of TOR 雷帕霉素不敏感的 TOR 伴侣
RLS 共振激光雷达replicative lifespan 复制寿命
ROS 活性氧reactive oxygen species 活性氧类
SIRT1sirtuin-1
SOD 超氧化物歧化酶superoxide dismutase 超氧化物歧化酶
Src 中国科学研究委员会proto-oncogene tyrosine-protein kinase 原癌基因酪氨酸蛋白激酶
STAT3signal transducer and activator of transcription 3 STAT3
T2DMtype 2 diabetes mellitus 2型糖尿病
telO2telomere maintenance 2 端粒维护2
TFEB/TFE3transcription factor EB/E3 转录因子/EB/E3
tti1telO2-interacting protein 1 Telo2相互作用蛋白1
TXNRD1thioredoxin reductase 硫氧还蛋白还原酶
ULK1Unc-51 like autophagy activating kinase 类似自噬激活激酶的 Unc-51
v-ATPase V-atp 酶vacuolar H+-adenosine triphosphatase ATPase 液泡 h +-ATP酶 atp 酶
V-ATPase V 型 atp 酶vacuolar (H+)-ATPase 液泡(h +)-atp 酶
YY1 Yyy1Ying-Yang 1

发表评论

邮箱地址不会被公开。 必填项已用*标注