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The COP9 signalosome mediates the Spt23 regulated fatty acid desaturation and ergosterol biosynthesis.

COP9 信号体介导 Spt23 调节的脂肪酸去饱和和麦角甾醇生物合成。

  • 影响因子:4.32
  • DOI:10.1096/fj.201902487R
  • 作者列表:"Sinha A","Israeli R","Cirigliano A","Gihaz S","Trabelcy B","Braus GH","Gerchman Y","Fishman A","Negri R","Rinaldi T","Pick E
  • 发表时间:2020-02-19
Abstract

:The COP9 signalosome (CSN) is a conserved eukaryotic complex, essential for vitality in all multicellular organisms and critical for the turnover of key cellular proteins through catalytic and non-catalytic activities. Saccharomyces cerevisiae is a powerful model organism for studying fundamental aspects of the CSN complex, since it includes a conserved enzymatic core but lacks non-catalytic activities, probably explaining its non-essentiality for life. A previous transcriptomic analysis of an S. cerevisiae strain deleted in the CSN5/RRI1 gene, encoding to the CSN catalytic subunit, revealed a downregulation of genes involved in lipid metabolism. We now show that the S. cerevisiae CSN holocomplex is essential for cellular lipid homeostasis. Defects in CSN assembly or activity lead to decreased quantities of ergosterol and unsaturated fatty acids (UFA); vacuole defects; diminished lipid droplets (LDs) size; and to accumulation of endoplasmic reticulum (ER) stress. The molecular mechanism behind these findings depends on CSN involvement in upregulating mRNA expression of SPT23. Spt23 is a novel activator of lipid desaturation and ergosterol biosynthesis. Our data reveal for the first time a functional link between the CSN holocomplex and Spt23. Moreover, CSN-dependent upregulation of SPT23 transcription is necessary for the fine-tuning of lipid homeostasis and for cellular health.

摘要

: COP9 信号体 (CSN) 是一种保守的真核复合体,对所有多细胞生物的活力至关重要,对通过催化和非催化活性周转关键细胞蛋白至关重要。酿酒酵母是研究 CSN 复合物基本方面的强大模式生物,因为它包括一个保守的酶核心,但缺乏非催化活性,可能解释了它对生命的非必要性。先前对 CSN5/RRI1 基因中缺失的酿酒酵母菌株的转录组学分析,编码 CSN 催化亚基,揭示了参与脂质代谢的基因下调。我们现在表明酿酒酵母 CSN 全复合物对细胞脂质稳态至关重要。CSN 组装或活性缺陷导致麦角甾醇和不饱和脂肪酸 (UFA) 数量减少; 液泡缺陷; 脂滴 (LDs) 大小减少; 内质网 (ER) 积累压力。这些发现背后的分子机制取决于 CSN 参与上调 spt23 的 mRNA 表达。Spt23 是一种新型的脂质去饱和和麦角甾醇生物合成激活剂。我们的数据首次揭示了 CSN 全复合物和 spt23 之间的功能联系。此外,CSN 依赖性 SPT23 转录上调对于脂质稳态的微调和细胞健康是必要的。

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影响因子:3.17
发表时间:2020-01-30
DOI:10.1111/jhn.12736
作者列表:["Hone M","Nugent AP","Walton J","McNulty BA","Egan B"]

METHODS:BACKGROUND:Given the importance of habitual dietary protein intake, distribution patterns and dietary sources in the aetiology of age-related declines of muscle mass and function, the present study examined these factors as a function of sex and age in Irish adults aged 18-90 years comprising The National Adult Nutrition Survey (NANS). METHODS:In total, 1051 (males, n = 523; females, n = 528) undertook a 4-day semi-weighed food diary. Total, body mass relative intake and percentage contribution to total energy intake of dietary protein were determined in addition to protein distribution scores (PDS), as well as the contribution of food groups, animal- and plant-based foods to total protein intake. RESULTS:Total and relative protein intake [mean (SD)] were highest in those aged 18-35 years [96 (3) g day , 1.32 (0.40) g kg day ], with lower protein intakes with increasing age (i.e. in adults aged ≥65 years [82 (22) g, 1.15 (0.34) g kg day , P < 0.001 for both]. Differences in protein intake between age groups were more pronounced in males compared to females. Protein distribution followed a skewed pattern for all age groups [breakfast, 15 (10) g; lunch, 30 (15) g; dinner, 44 (17) g]. Animal-based foods were the dominant protein source within the diet [63% (11%) versus 37% (11%) plant protein, P < 0.001]. CONCLUSIONS:Protein intake and the number of meals reaching the purported threshold for maximising post-prandial anabolism were highest in young adults, and lower with increasing age. For main meals, breakfast provided the lowest quantity of protein across all age categories and may represent an opportunity for improving protein distribution, whereas, in older adults, increasing the number of meals reaching the anabolic threshold regardless of distribution pattern may be more appropriate.

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影响因子:2.76
发表时间:2020-01-30
DOI:10.1152/japplphysiol.00631.2019
作者列表:["Bonomi AG","Ten Hoor GA","De Morree HM","Plasqui G","Sartor F"]

METHODS:BACKGROUND:Low cardiorespiratory fitness (CRF) increases risk of all-cause mortality and cardiovascular events. Periodic CRF assessment can have an important preventive function. OBJECTIVE:To develop a protocol-free method to estimate CRF in daily life based on heart rate (HR) and body acceleration measurements. METHODS:Acceleration and HR data were collected from 37 subjects (M=49%) while performing a standardized laboratory activity protocol (sitting, walking, running, cycling) and during a 5-days free-living monitoring period. CRF was determined by oxygen uptake (VO2max) during maximal exercise testing. A doubly-labeled water validated equation was used to predict total energy expenditure (TEE) from acceleration data. A fitness index was defined as the ratio between TEE and HR (TEE-pulse). Activity recognition techniques were used to process acceleration features and classify sedentary, ambulatory and other activity types. Regression equations based on TEE-pulse data from each activity type were developed to predict VO2max. RESULTS:TEE-pulse measured within each activity type of the laboratory protocol was highly correlated to VO2max (r from 0.74 to 0.91). Averaging the outcome of each activity-type specific equation based on TEE-pulse from the laboratory data led to accurate estimates of VO2max (RMSE: 300.0 mlO2/min or 10%). The difference between laboratory and free-living determined TEE-pulse was 3.7 ± 11% (r =0.85). The prediction method preserved the prediction accuracy when applied to free-living data (RMSE: 367 mlO2/min or 12%). CONCLUSIONS:Measurements of body acceleration and HR can be used to predict VO2max in daily life. Activity-specific prediction equations are needed to achieve highly accurate estimates of CRF.

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影响因子:3.76
发表时间:2020-01-31
DOI:10.1152/ajpgi.00386.2018
作者列表:["Farr S","Stankovic B","Hoffman S","Masoudpoor H","Baker C","Taher J","Dean A","Anakk S","Adeli K"]

METHODS:OBJECTIVE:Postprandial dyslipidemia is a common feature of insulin resistant states and contributes to increased cardiovascular disease risk. Recently, bile acids have been recognized beyond their emulsification properties as important signaling molecules that promote energy expenditure, improve insulin sensitivity, and lower fasting lipemia. While bile acid receptors have become novel pharmaceutical targets, their effects on postprandial lipid metabolism remain unclear. Here we investigated the potential role of bile acids in regulation of postprandial chylomicron production and triglyceride excursion. Approach and Results: Healthy C57BL/6 mice were given an intraduodenal infusion of taurocholic acid (TA) under fat-loaded conditions and circulating lipids were measured. Targeting of bile acid receptors was achieved with GW4064, a synthetic agonist to the farnesoid X receptor (FXR), and with deoxycholic acid (DCA), an activator of the Takeda G-protein-coupled receptor 5. TA, GW4064, and DCA treatments all lowered postprandial lipemia. FXR agonism also reduced intestinal triglyceride content and activity of microsomal triglyceride transfer protein, involved in chylomicron assembly. Importantly, TA effects (but not DCA) were largely lost in FXR knockout mice. These bile acid effects are reminiscent of the anti-diabetic hormone glucagon-like peptide-1 (GLP-1). While the GLP-1 receptor agonist exendin-4 retained its ability to acutely lower postprandial lipemia during bile acid sequestration and FXR deficiency, it did raise hepatic expression of the rate limiting enzyme for bile acid synthesis. CONCLUSIONS:Bile acid signaling may be an important mechanism of controlling dietary lipid absorption and bile acid receptors may constitute novel targets for the treatment of postprandial dyslipidemia.

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