脂肪组织蛋白质组学研究进展

脂肪组织不仅是机体的能量储存库,而且也是重要的内分泌器官。脂肪组织分泌多种激素和细胞因子,参与调节机体多种生理和病理过程。目前飞速发展的蛋白质组学技术,为深入研究脂肪发育的分子机制及其代谢紊乱发生的遗传机理提供了有力的工具。对蛋白质组学在脂肪组织中的研究进展进行了综述,为脂肪组织的发育调控及代谢疾病的治疗提供了新的思路。     

FGF21 mediates alcohol-induced adipose tissue lipolysis by activation of systemic release of catecholamine in mice

Alcohol consumption leads to adipose tissue lipoatrophy and mobilization of FFAs, which contributes to hepatic fat accumulation in alcoholic liver disease. This study aimed to investigate the role of fibroblast growth factor (FGF)21, a metabolic regulator, in the regulation of chronic-binge alcohol-induced adipose tissue lipolysis. FGF21 KO mice were subjected to chronic-binge alcohol exposure, and epididymal white adipose tissue lipolysis and liver steatosis were investigated. Alcohol exposure caused adipose intracellular cAMP elevation and activation of lipolytic enzymes, leading to FFA mobilization in both WT and FGF21 KO mice. However, alcohol-induced systemic elevation of catecholamine, which is known to be a major player in adipose lipolysis by binding to the β-adrenergic receptor, was markedly inhibited in KO mice. Supplementation with recombinant human FGF21 to alcohol-exposed FGF21 KO mice resulted in an increase in fat loss in parallel with an increase of circulating norepinephrine concentration. Furthermore, alcohol consumption-induced fatty liver was blunted in the KO mice, indicating an inhibition of fatty acid reverse transport from adipose to the liver in the KO mice. Taken together, our studies demonstrate that FGF21 KO mice are protected from alcohol-induced adipose tissue excess-lipolysis through a mechanism involving systemic catecholamine release.     

Friend or foe: Multiple roles of adipose tissue in cancer formation and progression

Obesity is well-known as the second factor for tumorigenesis after smoking and is bound up with the malignant progression of several kinds of cancers, including esophageal cancer, liver cancer, colorectal cancer, kidney cancer, and ovarian cancer. The increased morbidity and mortality of obesity-related cancer are mostly attributed to dysfunctional adipose tissue. The possible mechanisms connecting dysfunctional adipose tissue to high cancer risk mainly focus on chronic inflammation, obesity-related microenvironment, adipokine secretion disorder, and browning of adipose tissue, and so forth. The stromal vascular cells in adipose tissue trigger chronic inflammation through secreting inflammatory factors and promote cancer cell proliferation. Hypertrophic adipose tissues lead to metabolic disorders of adipocytes, such as abnormal levels of adipokines that mediate cancer progression and metastasis. Cancer patients often show adipose tissue browning and cancerous cachexia in an advanced stage, which lead to unsatisfied chemotherapy effect and poor prognosis. However, increasing evidence has shown that adipose tissue may display quite opposite effects in cancer development. Therefore, the interaction between cancers and adipose tissue exert a vital role in mediates adipose tissue dysfunction and further leads to cancer progression. In conclusion, targeting the dysfunction of adipose tissue provides a promising strategy for cancer prevention and therapy.     

Choosing the right type of serum for different applications of human adipose tissue–derived stem cells: influence on proliferation and differentiation abilities

Background aimsAdipose tissue–derived stem cells (ADSCs) are thought to have great potential in regenerative medicine. A xenoprotein-free culture and handling system is desirable. To date, there is only little and contradictory information about the influence of the different types of human serum on ADSC proliferation and differentiation.MethodsFirst, ADSCs were cultured in media containing regular human serum (HS plus) or fetal calf serum (FCS plus) with supplementation of growth factors for three passages. During passage 4, ADSC proliferative activity and adipogenic, osteogenic and chondrogenic differentiation ability was quantified. Second, ADSCs were cultured with three different human sera (regular human serum [HS], human serum from platelet-poor plasma [SPPP] or human serum from platelet-rich plasma [SPRP]) without supplementation of platelet-derived growth factor and assessed accordingly. The growth factor content of the different types of human sera was determined by means of multiplex protein assay and enzyme-linked immunosorbent assay.ResultsThe different sera did not affect ADSC doubling time significantly (P < 0.05). Specific glycerol-3-phosphat-dehydrogenase activity was significantly lower in cultures with SPRP (P < 0.01) compared with the other media compositions. Extracellular calcium deposition was significantly higher in cells differentiated in cultures with HS or SPPP compared with those with SPRP, HS plus or FCS (P < 0.01). Glycosaminoglycan content and collagen 2 were highest in cells cultured with SPRP (P < 0.001).ConclusionsCulturing ADSCs in human serum appears to be a reasonable and efficient alternative compared with FCS. With respect to the outcome of a sighted clinical application, it appears to be feasible to handle the cells in a serum suitable for the intended later use.     

Cryopreservation of adipose tissue

The main obstacle to achieving favorable outcome of soft-tissue augmentation after autologous fat transplantation is unpredictable long-term results due to the high rate of absorption in the grafted site. At the present time, adipose aspirates can only be used for immediate autologous fat grafting during the same procedure in which liposuction is performed; therefore adipose aspirates obtained from the procedure are usually discarded. it has been a strong desire of both surgeons and patients to be able to preserve the adipose aspirates, if an optimal technique were available, for potential future applications. For the last several years, cryopreservation of adipose tissue has been studied extensively in the author''s laboratory. Several findings from this exciting translational research will lead to develop a reliable method for long-term preservation of adipose tissue in the future. in addition, successful long-term preservation of adipose tissue may open a new era in adipose tissue related tissue regeneration.     

Modulation of adipose tissue thermogenesis as a method for increasing energy expenditure

There is a renewed interest in the role of adipose tissue in energy utilization and thermogenesis and its potential application in the treatment of metabolic disorders such as obesity and diabetes. The last few years have seen the identification of brown adipose tissue capable of metabolic activation in adult humans, the possibility of recruiting ‘beige’ adipocytes to increase energy expenditure, and the implication of molecules such as FGF21 and irisin in inducing increases in energy expenditure in adipose tissue. The translation of these findings into human trials to deliver safe, efficacious medicines remains a challenge.     

Pharmacological and nutritional agents promoting browning of white adipose tissue

The role of brown adipose tissue in the regulation of energy balance and maintenance of body weight is well known in rodents. Recently, interest in this tissue has re-emerged due to the realization of active brown-like adipose tissue in adult humans and inducible brown-like adipocytes in white adipose tissue depots in response to appropriate stimuli (“browning process”). Brown-like adipocytes that appear in white fat depots have been called “brite” (from brown-in-white) or “beige” adipocytes and have characteristics similar to brown adipocytes, in particular the capacity for uncoupled respiration. There is controversy as to the origin of these brite/beige adipocytes, but regardless of this, induction of the browning of white fat represents an attractive potential strategy for the management and treatment of obesity and related complications. Here, the different physiological, pharmacological and dietary determinants that have been linked to white-to-brown fat remodeling and the molecular mechanisms involved are reviewed in detail. In the light of available data, interesting therapeutic perspectives can be expected from the use of specific drugs or food compounds able to induce a program of brown fat differentiation including uncoupling protein 1 expression and enhancing oxidative metabolism in white adipose cells. However, additional research is needed, mainly focused on the physiological relevance of browning and its dietary control, where the use of ferrets and other non-rodent animal models with a more similar adipose tissue organization and metabolism to humans could be of much help. This article is part of a Special Issue entitled Brown and White Fat: From Signaling to Disease.     

Acute modulation of adipose tissue lipolysis by intravenous estrogens

Objective: The aim of this study was to determine whether intravenous (IV) conjugated estrogens (EST) acutely enhance the suppression of whole‐body or regional subcutaneous adipose tissue (SAT) lipolysis by insulin in postmenopausal women. Research Methods and Procedures: We assessed whole‐body lipolysis by [²H₅]glycerol rate of appearance (Glyc_RA) and abdominal and femoral SAT lipolysis (interstitial glycerol; Glyc_IS) by subcutaneous microdialysis. Postmenopausal women (n = 12) were studied on two occasions, with IV EST or saline control (CON), under basal conditions and during a 3‐stage (4, 8, and 40 mU/m²/min) hyperinsulinemic, euglycemic clamp. Ethanol outflow/inflow ratio and recovery of [¹³C]glycerol during microdialysis were used to assess blood flow changes and interstitial glycerol concentrations, respectively. Results: Compared with CON, EST did not affect systemic basal or insulin‐mediated suppression of lipolysis (Glyc_RA) or SAT nutritive blood flow. Basal Glyc_IS in SAT was reduced on the EST day. However, insulin‐mediated suppression of lipolysis in SAT was not significantly influenced by EST. Discussion: These findings suggest that estrogens acutely reduce basal lipolysis in SAT through an unknown mechanism but do not alter whole‐body or SAT suppression of lipolysis by insulin.     

噬菌体展示技术筛选bFGF模拟短肽

目的：通过噬菌体展示技术筛选得到与FGFR结合的bFGF模拟短肽,为bFGF肽类抑制剂的研发提供实验基础。方法：以Balb/c 3T3细胞为靶标,以COS-7细胞作消减,对噬菌体随机七肽库进行4轮生物淘洗,再采用ELISA检测单克隆噬菌体对Balb/c 3T3亲和性和特异性,选取阳性克隆进行DNA测序分析。结果：从富集的噬菌体中获得12个阳性克隆,获得一组疏水性七肽及共同基序PR。结论：利用肽类新药开发的重要工具--噬菌体展示技术,得到2段bFGF的受体结合模拟肽,可望作为bFGF抑制剂的先导肽。     

FGF21 mediates the lipid metabolism response to amino acid starvation

Lipogenic gene expression in liver is repressed in mice upon leucine deprivation. The hormone fibroblast growth factor 21 (FGF21), which is critical to the adaptive metabolic response to starvation, is also induced under amino acid deprivation. Upon leucine deprivation, we found that FGF21 is needed to repress expression of lipogenic genes in liver and white adipose tissue, and stimulate phosphorylation of hormone-sensitive lipase in white adipose tissue. The increased expression of Ucp1 in brown adipose tissue under these circumstances is also impaired in FGF21-deficient mice. Our results demonstrate the important role of FGF21 in the regulation of lipid metabolism during amino acid starvation.     

Modulation of white adipose tissue proteome by aging and calorie restriction

Aging is associated with an accrual of body fat, progressive development of insulin resistance and other obesity comorbidities that contribute to decrease life span. Caloric restriction (CR), which primarily affects energy stores in adipose tissue, is known to extend life span and retard the aging process in animal models. In this study, a proteomic approach combining 2‐DE and MS was used to identify proteins modulated by aging and CR in rat white adipose tissue proteome. Proteomic analysis revealed 133 differentially expressed spots, 57 of which were unambiguously identified by MS. Although CR opposed part of the age‐associated protein expression patterns, many effects of CR were on proteins unaltered by age, suggesting that the effects of CR on adipose tissue are only weakly related to those of aging. Particularly, CR and aging altered glucose, intermediate and lipid metabolism, with CR enhancing the expression of enzymes involved in oxalacetate and NADPH production, lipid biosynthesis and lipolysis. Consistently, insulin‐β and β3‐adrenergic receptors were also increased by CR, which denotes improved sensitivity to lipogenic/lipolytic stimuli. Other beneficial outcomes of CR were an improvement in oxidative stress, preventing the age‐associated decrease in several antioxidant enzymes. Proteins involved in cytoskeleton, iron storage, energy metabolism and several proteins with novel or unknown functions in adipose tissue were also modulated by age and/or CR. Such orchestrated changes in expression of multiple proteins provide insights into the mechanism underlying CR effects, ultimately allowing the discovery of new markers of aging and targets for the development of CR‐mimetics.     

Exercise enhancement by RGS14 disruption is mediated by brown adipose tissue

Enhanced exercise capacity is not only a feature of healthful aging, but also a therapy for aging patients and patients with cardiovascular disease. Disruption of the Regulator of G Protein Signaling 14 (RGS14) in mice extends healthful lifespan, mediated by increased brown adipose tissue (BAT). Accordingly, we determined whether RGS14 knockout (KO) mice exhibit enhanced exercise capacity and the role of BAT in mediating exercise capacity. Exercise was performed on a treadmill and exercise capacity was assessed by maximal running distance and work to exhaustion. Exercise capacity was measured in RGS14 KO mice and their wild types (WT), and also in WT mice with BAT transplantation from RGS14 KO mice or from other WT mice. RGS14 KO mice demonstrated 160 ± 9% increased maximal running distance and 154 ± 6% increased work to exhaustion, compared to WT mice. RGS14 KO BAT transplantation to WT mice, resulted in a reversal of phenotype, with the WT mice receiving the BAT transplant from RGS14 KO mice demonstrating 151 ± 5% increased maximal running distance and 158 ± 7% increased work to exhaustion, at three days after BAT transplantation, compared to RGS14 KO donors. BAT transplantation from WT to WT mice also resulted in increased exercise performance, but not at 3 days, but only at 8 weeks after transplantation. The BAT induced enhanced exercise capacity was mediated by (1) mitochondrial biogenesis and SIRT3; (2) antioxidant defense and the MEK/ERK pathway, and increased hindlimb perfusion. Thus, BAT mediates enhanced exercise capacity, a mechanism more powerful with RGS14 disruption.     

Biologic properties of mesenchymal stem cells derived from bone marrow and adipose tissue

The biologic characteristics of mesenchymal stem cells (MSCs) isolated from two distinct tissues, bone marrow and adipose tissue were evaluated in these studies. MSCs derived from human and non-human primate (rhesus monkey) tissue sources were compared. The data indicate that MSCs isolated from rhesus bone marrow (rBMSCs) and human adipose tissue (hASCs) had more similar biologic properties than MSCs of rhesus adipose tissue (rASCs) and human bone marrow MSCs (hBMSCs). Analyses of in vitro growth kinetics revealed shorter doubling time for rBMSCs and hASCs. rBMSCs and hASCs underwent significantly more population doublings than the other MSCs. MSCs from all sources showed a marked decrease in telomerase activity over extended culture; however, they maintained their mean telomere length. All of the MSCs expressed embryonic stem cell markers, Oct-4, Rex-1, and Sox-2 for at least 10 passages. Early populations of MSCs types showed similar multilineage differentiation capability. However, only the rBMSCs and hASCs retain greater differentiation efficiency at higher passages. Overall in vitro characterization of MSCs from these two species and tissue sources revealed a high level of common biologic properties. However, the results demonstrate clear biologic distinctions, as well.     

EPO对高脂喂养小鼠棕色脂肪组织PRDM16、FGF21表达及STAT3磷酸化水平的影响

目的：探索促红细胞生成素（EPO）对高脂饲料（HFD）喂养小鼠血糖和血浆胰岛素水平、胰岛素抵抗指数（HOMA-IR）、糖耐量,以及棕色脂肪组织中含PR结构域蛋白16（PRDM16）、信号转导与转录激活因子3（STAT3）磷酸化水平（p-STAT3/STAT3）、成纤维细胞生长因子21（FGF21）mRNA以及蛋白质表达的影响,为肥胖及其并发症的发生机制提供线索。方法：20只高脂饲料喂养的C57BL/6J雄性小鼠随机分为对照组（HFD-Con）和EPO组（HFD-EPO）,两组分别腹腔注射生理盐水和EPO（200 IU/kg）,每周3次,连续4周。4周后检测两组动物的体重、血糖与血浆胰岛素水平、HOMA-IR及糖耐量的变化;分别使用实时定量PCR法和Western blot法检测棕色脂肪组织中PRDM16、STAT3、FGF21 mRNA和蛋白质水平。结果：腹腔注射EPO 4周后,HFD-EPO组小鼠体重为（26.65±0.85）g,HFD-Con组体重为（31.50±1.60）g,P<0.01。HFD-Con组血糖为（91.06±9.86）mg/dl,HFD-EPO组为（62.79±8.09）mg/dl,P<0.01;HFD-EPO组小鼠血浆胰岛素水平为（10.56±1.06）μU/ml,HFD-Con组为（13.2±1.1）μU/ml,P<0.01。与HFD-Con组比较,HFD-EPO组的糖耐量水平显著改善,胰岛素抵抗指数下降;HFD-EPO组动物棕色脂肪组织中PRDM16、FGF21mRNA以及蛋白质表达,p-STAT/STAT3水平均显著增加,两组小鼠肝脏中FGF21 mRNA含量、血浆中FGF21含量无明显差异。结论：EPO可能通过增加棕色脂肪组织中PRDM16表达促进棕色脂肪组织的分化,降低高脂喂养小鼠的血糖水平、改善高脂喂养小鼠的糖代谢状态。     

Basic fibroblast growth factor can induce exclusively neural tissue in Triturus ectoderm explants

Ectoderm was isolated from early gastrulae of Triturus alpestris and induced with recombinant basic fibroblast growth factor (b-FGF). Neural tissue differentiated in about 38% of the explants which were induced by 2,5 g/ml FGF. These explants do not contain other tissues, or contain only small amounts of mesenchyme and melanophores which are probably derived from induced neural crest. It is therefore unlikely that these neural tissues are secondarily induced. The other explants contain predominantly blastema tissue, endothelium/ mesothelium, small amounts of skeletal muscle and, rarely, notochord besides neural tissues. The mitotic rate was enhanced in about 20% of the induced explants. Possible mechanisms for the unexpected neural-inducing activity of b-FGF in Triturus ectoderm are discussed.