昆虫体内储存蛋白的研究进展

储存蛋白是昆虫体内普遍存在的一种特异性血淋巴蛋白 ,通常在幼虫的脂肪体内合成 ,释放进入血淋巴中。化蛹时 ,又被脂肪体选择性吸收 ,作为氨基酸的贮存库对成虫变态发育和雌性卵发育起着重要的作用。该文介绍了昆虫体内储存蛋白的特性、功能、及调节机制。     

Mouse fat storage‐inducing transmembrane protein 2 (FIT2) promotes lipid droplet accumulation in plants

Fat storage‐inducing transmembrane protein 2 (FIT2) is an endoplasmic reticulum (ER)‐localized protein that plays an important role in lipid droplet (LD) formation in animal cells. However, no obvious homologue of FIT2 is found in plants. Here, we tested the function of FIT2 in plant cells by ectopically expressing mouse (Mus musculus) FIT2 in Nicotiana tabacum suspension‐cultured cells, Nicotiana benthamiana leaves and Arabidopsis thaliana plants. Confocal microscopy indicated that the expression of FIT2 dramatically increased the number and size of LDs in leaves of N. benthamiana and Arabidopsis, and lipidomics analysis and mass spectrometry imaging confirmed the accumulation of neutral lipids in leaves. FIT2 also increased seed oil content by ~13% in some stable, overexpressing lines of Arabidopsis. When expressed transiently in leaves of N. benthamiana or suspension cells of N. tabacum, FIT2 localized specifically to the ER and was often concentrated at certain regions of the ER that resembled ER‐LD junction sites. FIT2 also colocalized at the ER with other proteins known to be involved in triacylglycerol biosynthesis or LD formation in plants, but not with ER resident proteins involved in electron transfer or ER‐vesicle exit sites. Collectively, these results demonstrate that mouse FIT2 promotes LD accumulation in plants, a surprising functional conservation in the context of a plant cell given the apparent lack of FIT2 homologues in higher plants. These results suggest also that FIT2 expression represents an effective synthetic biology strategy for elaborating neutral lipid compartments in plant tissues for potential biofuel or bioproduct purposes.     

Adipose Depletion and Apoptosis Induced by Trans-10, Cis-12 Conjugated Linoleic Acid in Mice*

Objective: To compare the effectiveness of a conjugated linoleic acid (CLA) isomer mixture (mCLA) with each main isomer [trans-10,cis-12 CLA (CLA10,12) and cis-9,trans-11 CLA (CLA9,11)] in causing body lipid loss and adipose tissue apoptosis. Research Methods and Procedures: Mice selected over 16 generations for high (MH) or low (ML) energy expenditure and a control group (MC) were fed diets containing either soy oil or soy oil plus mCLA, CLA10,12, or CLA9,11 for 5 days in one study and 14 days in a second study. Results: Mice fed mCLA or CLA10,12 had less body lipid (p < 0.05), smaller retroperitoneal fat pads (p < 0.05), and ate less (p < 0.01) than mice fed no CLA or CLA9,11 for 5 days. Mice consuming 1% mCLA or 0.5% CLA10,12 gained less weight (p < 0.01) and had less body lipid (p < 0.05) and smaller epididymal (p < 0.05) and retroperitoneal fat pads (p < 0.01) than mice consuming either control or 0.5% CLA9,11-containing diets for 14 days. Only mCLA and CLA10,12 increased apoptosis in retroperitoneal fat pads (p < 0.01). The effects of mCLA and CLA10,12 were independent of genetic line except for the effect on adipocyte apoptosis. Mice of the MH line were slightly less sensitive than MC or ML mice to CLA-induced adipose tissue apoptosis. Discussion: CLA10,12, but not CLA9,11, can induce both body fat loss and adipose apoptosis. Although mice of a genotype with less body fat and greater metabolic rate and feed intake appear less sensitive, these CLA effects are robust for mice of varying metabolic background.     

Neutral fat hydrolysis and long-chain fatty acid oxidation during anaerobic digestion of slaughterhouse wastewater

Neutral fat hydrolysis and long-chain fatty acid (LCFA) oxidation rates were determined during the digestion of slaughterhouse wastewater in anaerobic sequencing batch reactors operated at 25 degrees C. The experimental substrate consisted of filtered slaughterhouse wastewater supplemented with pork fat particles at various average initial sizes (D(in)) ranging from 60 to 450 microm. At the D(in) tested, there was no significant particle size effect on the first-order hydrolysis rate. The neutral fat hydrolysis rate averaged 0.63 +/- 0.07 d(-1). LCFA oxidation rate was modelled using a Monod-type equation. The maximum substrate utilization rate (kmax) and the half-saturation concentration (Ks) averaged 164 +/- 37 mg LCFA/L/d and 35 +/- 31 mg LCFA/L, respectively. Pork fat particle degradation was mainly controlled by LCFA oxidation rate and, to a lesser extent, by neutral fat hydrolysis rate. Hydrolysis pretreatment of fat-containing wastewaters and sludges should not substantially accelerate their anaerobic treatment. At a D(in) of 450 microm, fat particles were found to inhibit methane production during the initial 20 h of digestion. Inhibition of methane production in the early phase of digestion was the only significant effect of fat particle size on anaerobic digestion of pork slaughterhouse wastewater. Soluble COD could not be used to determine the rate of lipid hydrolysis due to LCFA adsorption on the biomass.     

Ultrasonographic measurements of localized fat accumulation in Shetland pony mares fed a normal v. a high energy diet for 2 years

Health risks associated with obesity are more likely a factor of the localization of fat excess, rather than of elevated BW per se. The aim of this randomized controlled clinical trial was to determine the effect of a long-term high energy diet on BW, fat accumulation and localization. Eight Shetland pony mares, 3 to 7 years old, were randomly divided into a control and a high energy (HE) diet group fed either maintenance or double maintenance energy requirements (200% net energy (NE)) for two consecutive summers, with a low energy diet in the winter in between. Body condition score (BCS) did not differ between the groups at the onset of the study (control 5.6±0.75 v. HE 6.3±0.5). From 12 weeks after starting the diet, ultrasonography of five different locations (retroperitoneal, axillary, withers, intercostal and rump) for adipose deposition, BCS and BW were measured monthly during the period that ponies received different diets. Statistical analysis was performed using a linear mixed-effects model with post hoc Bonferroni testing. P values <0.05 were considered significant. At week 12 after the onset of the diet, fat thickness in the HE group was significantly greater than in the control group. During the monitoring period, the HE group showed a significant increase in mean (±SE) BW (+52%, 265±13.94kg) and BCS (+70%; to 9.0±0.4), while the control group was unchanged (BW 160±13.98 kg; BCS 3.8±0.4). At all locations, the fat depth in the HE group increased significantly, with the highest increase noted for retroperitoneal deposits. The conclusions were that a 200% NE diet induced subcutaneous and retroperitoneal fat accumulation, with the greatest increase in intra-abdominal deposits. The moderate increase of the subcutaneous fat depth followed by a plateau phase suggests the existence of a limit of adipose tissue expandability, as in man.     

利拉鲁肽联合达格列净对超重或肥胖2型糖尿病患者肾功能、氧化应激以及内脏脂肪含量的影响

摘要 目的：探讨利拉鲁肽联合达格列净对超重或肥胖2型糖尿病（T2DM）患者肾功能、氧化应激以及内脏脂肪含量的影响。方法：选取我院于2018年1月~2020年5月期间接收的108例超重或肥胖T2DM患者,按照随机数字表法分为对照组（n=54）和观察组（n=54）。对照组给予利拉鲁肽治疗,观察组给予利拉鲁肽联合达格列净治疗,均治疗12周。对比两组肾功能[血胱抑素 C（CysC）、血肌酐（Scr）、血尿酸（SUA）]、氧化应激[丙二醛（MDA）、谷胱甘肽过氧化物酶（GSH-PX）、超氧化物歧化酶（SOD）]、体质量指数（BMI）、腰围、血糖指标[空腹血糖（FBG）、餐后2 h血糖（2hPBG）、糖化血红蛋白（HbA1c）]以及体成分指标（全身脂肪百分比、内脏脂肪含量）,记录两组治疗期间不良反应情况。结果：两组治疗后BMI、腰围、2hPBG、FBG、HbA1c均下降,且观察组较对照组低（P<0.05）。两组治疗后MDA均下降,且观察组较对照组低（P<0.05）,两组治疗后SOD、GSH-PX均升高,且观察组较对照组高（P<0.05）。两组治疗后全身脂肪百分比、内脏脂肪含量均下降,且观察组较对照组低（P<0.05）。两组治疗前后CysC、Scr、SUA组内及组间对比均无统计学差异（P>0.05）。两组不良反应发生率对比无统计学差异（P>0.05）。结论：超重或肥胖T2DM患者利拉鲁肽治疗基础上联合达格列净,降糖效果确切,减轻机体氧化应激,降低内脏脂肪含量,对肾功能无显著影响,且不增加不良反应发生率。     

Effects of polymorphisms in nucleotide-binding oligomerization domains 1 and 2 on biomarkers of the metabolic syndrome and type II diabetes

The innate immune receptor toll-like receptor 4 (TLR4) has been implicated in mediating some of the effects of dietary lipids on inflammation and type 2 diabetes (T2D). Similar to TLR4, the nucleotide-binding oligomerization domains (Nods) 1 and 2 are also proteins of innate immunity, which can respond to lipids and initiate pro-inflammatory signalling that plays a role in the aetiology of T2D. The objective was to determine the effect of Nod1 (Glu266Lys) and Nod2 (Ser268Pro) genotypes on factors associated with the metabolic syndrome (MetS), and whether they modify the association between dietary lipids and biomarkers of the MetS. Men and women (n = 998) between the ages of 20–29 years were genotyped for both polymorphisms, completed a one-month, semiquantitative food frequency questionnaire and provided a fasting blood sample. The Glu266Lys polymorphism in Nod1 was not associated with any of the biomarkers of the MetS, but modified the association between dietary saturated fat (SFA) and insulin sensitivity, as measured by HOMA-IR (p for interaction = 0.04). Individuals with the Glu/Glu or Glu/Lys genotype showed no significant relationship between dietary SFA and HOMA-IR (β = −0.002 ± 0.006, p = 0.77; and β = −0.003 ± 0.006, p = 0.61), while those with the Lys/Lys genotype showed a positive association (β = 0.033 ± 0.02, p = 0.03). The Nod2 Ser268Pro polymorphism was not associated with components of the MetS and did not modify the relationship between dietary lipid intake and the biomarkers of MetS. In summary, the Nod1 Glu266Lys polymorphism modifies the relationship between dietary SFA intake and HOMA-IR, suggesting that Nod1 may act as an intracellular lipid sensor affecting insulin sensitivity.     

Diet‐induced obesity accelerates the onset of terminal phenotypes in α‐synuclein transgenic mice

Parkinson's disease (PD) and diabetes belong to the most common neurodegenerative and metabolic syndromes, respectively. Epidemiological links between these two frequent disorders are controversial. The neuropathological hallmarks of PD are protein aggregates composed of amyloid‐like fibrillar and serine‐129 phosphorylated (pS129) α‐synuclein (AS). To study if diet‐induced obesity could be an environmental risk factor for PD‐related α‐synucleinopathy, transgenic (TG) mice, expressing the human mutant A30P AS in brain neurons, were subjected after weaning to a lifelong high fat diet (HFD). The TG mice became obese and glucose‐intolerant, as did the wild‐type controls. Upon aging, HFD significantly accelerated the onset of the lethal locomotor phenotype. Coinciding with the premature movement phenotype and death, HFD accelerated the age of onset of brainstem α‐synucleinopathy as detected by immunostaining with antibodies against pathology‐associated pS129. Amyloid‐like neuropathology was confirmed by thioflavin S staining. Accelerated onset of neurodegeneration was indicated by Gallyas silver‐positive neuronal dystrophy as well as astrogliosis. Phosphorylation of the activation sites of the pro‐survival signaling intermediate Akt was reduced in younger TG mice after HFD. Thus, diet‐induced obesity may be an environmental risk factor for the development of α‐synucleinopathies. The molecular and cellular mechanisms remain to be further elucidated.

     

Proteomic and cell biological profiling of the renal phenotype of the mdx-4cv mouse model of Duchenne muscular dystrophy

The X-linked inherited muscle wasting disease Duchenne muscular dystrophy, which is caused by primary abnormalities in the membrane cytoskeletal protein dystrophin, is a multi-system disorder. Highly progressive forms of dystrophinopathy are associated with a complex secondary pathophysiology, including renal dysfunction. It was therefore of interest to carry out a systematic survey of potential proteome-wide changes in the kidney of the established mdx-4cv mouse model of dystrophinopathy. Of 5878 mass spectrometrically identified kidney proteins, 82 versus 142 proteins were shown to be decreased or increased, respectively, in association with muscular dystrophy. The most decreased versus increased protein species are the ACSM3 isoform of mitochondrial acyl-coenzyme A synthetase and the FABP1 isoform of fatty acid binding protein, respectively. Both proteomic findings were verified by immunofluorescence microscopy and immunoblot analysis. Interestingly, haematoxylin/eosin staining indicated diffuse whitish deposits in the mdx-4cv kidney, and an increased intensity of Sudan Black labelling of kidney cells revealed ectopic fat deposition. Although the proteomic results and cell biological findings do not demonstrate a direct functional link between increased FABP1 and fat accumulation, the results suggest that the up-regulation of FABP1 may be related to abnormal fat metabolism. This makes FABP1 potentially a novel pathobiochemical indicator for studying kidney abnormalities in the mdx-4cv model of dystrophinopathy.     

Comparison of variations between percentage of body fat, body mass index and daily physical activity among young Japanese and Thai female students

ABSTRACT: BACKGROUND: In our series of investigations concerning the causes of seasonal change in fat accumulation in young university students, we could not find any contribution of seasonal variation in the ratio of carbohydrate and fat metabolism to that of body fat percentage in Japanese and Thai participants. After our previous study, we examined the effect of daily physical activity on body fat percentage to look for the major causes of seasonal change in fat accumulation in young university students. FINDINGS: In this study, we measured participants' (young Japanese and Thai university students) daily physical activity by a uniaxial accelerometer in addition to the measurements of body fat percentage and body mass index by a bioelectrical impedance meter. We found that there was significant and moderate negative correlation between body fat percentage and daily step counts among Japanese but not Thai participants. We observed significant, moderate and positive correlations between the percentage of body fat and body mass index among Japanese and Thai participants. CONCLUSIONS: Daily physical activity plays an important role in the seasonal variation of body fat percentage of Japanese female students. Our present study also confirmed the importance of daily physical activity for controlling body mass index and for the prevention of obesity.