NAD+代谢在细胞功能及相关疾病中作用的研究进展

烟酰胺腺嘌呤二核苷酸(NAD⁺)是细胞内一种重要的辅助调节因子,NAD⁺代谢紊乱与细胞功能损伤、生理改变及疾病的发生发展密切相关。在衰老、听力障碍、心脏损伤等代谢性和年龄相关性疾病的发生过程中都伴随着NAD⁺水平下降,因此,通过补充恢复NAD⁺水平可为这些疾病的治疗提供了一种新思路。     

PARP-1抑制剂通过激活SIRT1-PGC-1α轴减轻慢性阻塞性肺疾病大鼠的炎症和氧化应激反应

目的：通过构建慢性阻塞性肺疾病（COPD）大鼠实验模型,探讨聚二磷酸腺苷核糖聚合酶-1(PARP-1)抑制剂是否通过调控沉默信息调节因子相关酶1(SIRT1)、过氧化物酶体增殖物激活受体γ辅激活因子1α(PGC-1α)减轻COPD大鼠的炎症和氧化应激反应,探究SIRT1-PGC-1α轴作为PARP-1抑制剂作用新靶点的可能性。方法：将48只SD大鼠随机选取12只作为健康组,剩余大鼠构建COPD实验模型,将造模成功的大鼠随机分为模型组、PARP-1抑制剂处理组、PARP-1抑制剂+PGC-1α抑制剂组,HE染色观察肺组织病理形态变化,ELISA检测大鼠肺组织TNF-α、IL-6、IL-1β、丙二醛（MDA）、超氧化物歧化酶（SOD）水平,荧光定量PCR法检测各组大鼠SIRT1、PGC-1α mRNA表达水平,Western blot检测SIRT1、PGC-1α蛋白表达。结果：健康组大鼠肺组织结构完整,与健康组相比,模型组大鼠肺组织产生结构损伤,有大量炎症细胞浸润,肺泡灌洗液中TNF-α、IL-1β、IL-6含量均显著升高,血清中MDA含量显著升高,SOD含量显著降低,SIRT1、PGC-...     

The general anesthetic sevoflurane affects the expression of clock gene mPer2 accompanying the change of NAD+ level in the suprachiasmatic nucleus of mice

Sevoflurane is an anesthetic for the general anesthesia. In this study, we showed that sevoflurane anesthesia affects the expression of mouse Per2 (mPer2), which is a clock gene in the brain which is considered the organ where the anesthetics act in. 64.5% of mPer2 circadian expression was repressed under anesthesia in the suprachiasmatic nucleus (SCN) of the brain. After recovering from the anesthesia, the repressed mPer2 expression was restored to the same level as in non anesthesia-treated mice. This repression pattern was also observed in the subsequent phases of diurnal mPer2 expression. However, obvious phase-shift in the mPer2 expression was not showed in this study. On the other hand, the behavior analysis in this experiment exhibited that the phases in the circadian behavioral rhythm were shifted backwards. We also measured the NAD(+) level in the SCN, which was a mediator regulating the mPer2 expression. Then, significant increase of NAD(+) was detected under the anesthesia. These results indicate that the anesthesia induces the increase of NAD(+), and consequently leads to the repression of mPer2 expression and modifies the circadian expression pattern and diurnal behavioral rhythm of mice. Furthermore, the modification of mPer2 expression by the anesthesia is considered to affect various gene expressions.     

SIRT1 stimulation by polyphenols is affected by their stability and metabolism

Silent information regulator two ortholog 1 (SIRT1) is the human ortholog of the yeast sir2 protein; one of the most important regulators of lifespan extension by caloric restriction in several organisms. Dietary polyphenols, abundant in vegetables, fruits, cereals, wine and tea, were reported to stimulate the deacetylase activity of recombinant SIRT1 protein and could therefore be potential regulators of aging associated processes. However, inconsistent data between effects of polyphenols on the recombinant SIRT1 and on in vivo SIRT1, led us to investigate the influence of (1) stability of polyphenols under experimental conditions and (2) metabolism of polyphenols in human HT29 cells, on stimulation of SIRT1. With an improved SIRT1 deacetylation assay we found three new polyphenolic stimulators. Epigallocatechin galate (EGCg, 1.76-fold), epicatechin galate (ECg, 1.85-fold) and myricetin (3.19-fold) stimulated SIRT1 under stabilizing conditions, whereas without stabilization, these polyphenols strongly inhibited SIRT1, probably due to H2O2 formation. Using metabolically active HT29 cells we were able to show that quercetin (a stimulator of recombinant SIRT1) could not stimulate intracellular SIRT1. The major quercetin metabolite in humans, quercetin 3-O-glucuronide, slightly inhibited the recombinant SIRT1 activity which explains the lack of stimulatory action of quercetin in HT29 cells. This study shows that the stimulation of SIRT1 is strongly affected by polyphenol stability and metabolism, therefore extrapolation of in vitro SIRT1 stimulation results to physiological effects should be done with caution.     

Bioenergetics of aging and calorie restriction

Aging is a physiological process that involves a multi-factorial set of deleterious changes. These alterations are caused by an exponential increase in damage to macromolecules. This process is likely due to the cumulative effects of oxidative stress over time. One area of ongoing research in gerontology has focused on determining why there is an age-dependent decrease in cellular bioenergetics. The aim of this review is to summarize the recent findings on the effects of aging and calorie restriction on energy metabolism. The effect of calorie restriction on age-associated changes in bioenergetic parameters will be examined.