Continuous administration of polyphenols from aqueous rooibos (Aspalathus linearis) extract ameliorates dietary-induced metabolic disturbances in hyperlipidemic mice

The incidence of obesity and related metabolic diseases is increasing globally. Current medical treatments often fail to halt the progress of such disturbances, and plant-derived polyphenols are increasingly being investigated as a possible way to provide safe and effective complementary therapy. Rooibos (Aspalathus linearis) is a rich source of polyphenols without caloric and/or stimulant components. We have tentatively characterized 25 phenolic compounds in rooibos extract and studied the effects of continuous aqueous rooibos extract consumption in mice. The effects of this extract, which contained 25% w/w of total polyphenol content, were negligible in animals with no metabolic disturbance but were significant in hyperlipemic mice, especially in those in which energy intake was increased via a Western-type diet that increased the risk of developing metabolic complications. In these mice, we found hypolipemiant activity when given rooibos extract, with significant reductions in serum cholesterol, triglyceride and free fatty acid concentrations. Additionally, we found changes in adipocyte size and number as well as complete prevention of dietary-induced hepatic steatosis. These effects were not related to changes in insulin resistance. Among other possible mechanisms, we present data indicating that the activation of AMP-activated protein kinase (AMPK) and the resulting regulation of cellular energy homeostasis may play a significant role in these effects of rooibos extract. Our findings suggest that adding polyphenols to the daily diet is likely to help in the overall management of metabolic diseases.     

Cytoplasmic receptor-interacting protein 140 (RIP140) interacts with perilipin to regulate lipolysis

Receptor-interacting protein 140 (RIP140) is abundantly expressed in mature adipocyte and modulates gene expression involved in lipid and glucose metabolism. Protein kinase C epsilon and protein arginine methyltransferase 1 can sequentially stimulate RIP140 phosphorylation and then methylation, thereby promoting its export to the cytoplasm. Here we report a lipid signal triggering cytoplasmic accumulation of RIP140, and a new functional role for cytoplasmic RIP140 in adipocyte to regulate lipolysis. Increased lipid content, particularly an elevation in diacylglycerol levels, promotes RIP140 cytoplasmic accumulation and increased association with lipid droplets (LDs) by its direct interaction with perilipin. By interacting with RIP140, perilipin more efficiently recruits hormone-sensitive lipase (HSL) to LDs and enhances adipose triglyceride lipase (ATGL) forming complex with CGI-58, an activator of ATGL. Consequentially, HSL can more readily access its substrates, and ATGL is activated, ultimately enhancing lipolysis. In adipocytes, blocking cytoplasmic RIP140 accumulation reduces basal and isoproterenol-stimulated lipolysis and the pro-inflammatory potential of their conditioned media (i.e. activating NF-κB and inflammatory genes in macrophages). These results show that in adipocytes with high lipid contents, RIP140 increasingly accumulates in the cytoplasm and enhances triglyceride catabolism by directly interacting with perilipin. The study suggests that reducing nuclear export of RIP140 might be a useful means of controlling adipocyte lipolysis.     

Up-regulation of the novel proinflammatory adipokines lipocalin-2, chitinase-3 like-1 and osteopontin as well as angiogenic-related factors in visceral adipose tissue of patients with colon cancer

Background

Obesity is widely recognised as an important risk factor for colorectal cancer (CC).

Aim

The study aimed to evaluate the effect of CC on circulating concentrations and gene expression levels of inflammatory and angiogenesis-related factors in human visceral adipose tissue (VAT).

Methods

VAT biopsies were obtained from 18 healthy individuals and 11 patients with CC. Real-time polymerase chain reactions were performed to quantify gene expression levels and zymographic analyses were used to determine the activity of matrix metalloproteinases (MMPs).

Results

Patients with CC exhibited increased mRNA expression levels of lipocalin-2 (P=.014), osteopontin (P=.027), tumor necrosis factor-α (TNF-α) (P=.016) and chitinase-3 like-1 (P=.006) compared to control subjects in VAT. Gene expression levels of hypoxia-inducible factor-1 α, vascular endothelial growth factor and MMP-2 were significantly higher (P<.05) in VAT of patients with CC. The expression of insulin-like growth factor I, insulin growth factor binding protein 3 and MMP-9 followed the same trend, although no significant differences were reached. The enzymatic activity of MMP-9 was increased (P<.001) in patients with CC. Furthermore, individuals with CC showed increased (P<.05) circulating concentrations of the inflammatory markers interleukin-6, tumour necrosis factor α and hepatocyte growth factor, whereas levels of the anti-inflammatory adipokine adiponectin were decreased (P<.01).

Conclusion

These findings represent the first observation that mRNA levels of the novel inflammatory factors lipocalin-2, chitinase-3 like-1 and osteopontin are increased in human VAT of subjects with CC. This observation together with the up-regulation of angiogenic factors suggests that adipokines secreted by VAT may be involved in the development of colon cancer.     

Systemic transplantation of human adipose-derived stem cells stimulates bone repair by promoting osteoblast and osteoclast function

Systemic transplantation of adipose-derived stem cells (ASCs) is emerging as a novel therapeutic option for functional recovery of diverse damaged tissues. This study investigated the effects of systemic transplantation of human ASCs (hASCs) on bone repair. We found that hASCs secrete various bone cell-activating factors, including hepatocyte growth factor and extracellular matrix proteins. Systemic transplantation of hASCs into ovariectomized mice induced an increased number of both osteoblasts and osteoclasts in bone tissue and thereby prevented bone loss. We also observed that conditioned medium from hASCs is capable of stimulating proliferation and differentiation of osteoblasts via Smad/extracellular signal-regulated kinase (ERK)/JNK (c-jun NH(2) -terminal kinase) activation as well as survival and differentiation of osteoclasts via ERK/JNK/p38 activation in vitro. Overall, our findings suggest that paracrine factors secreted from hASCs improve bone repair and that hASCs can be a valuable tool for use in osteoporosis therapy.     

mRNA expression of genes involved in fatty acid utilization in skeletal muscle and white adipose tissues of sows during lactation

Rodents are able to lower fatty acid utilization in liver and muscle during lactation in order to spare fatty acids for the production of milk triacylglycerols, an effect which is mediated by a down-regulation of peroxisome proliferator-activated receptor α (PPARα). The present study was performed to investigate whether similar fatty acid sparing effects are developing in lactating sows. We considered PPARα and its target genes involved in fatty acid utilization in biopsy samples from muscle and adipose tissue of lactating compared to non-lactating sows. In muscle, PPARα target genes involved in fatty acid utilization were up-regulated during lactation indicating that the fatty acid utilization in muscle was increased. Activation of PPARα was probably due to increased concentrations of non-esterified fatty acids in plasma observed in the lactating sows. In contrast to muscle, PPARα and its target genes involved in β-oxidation in white adipose tissue were down-regulated in early lactation. Overall, the present study shows that sows, unlike rats, are not able to reduce the fatty acid utilization in muscle in order to spare fatty acids for milk production. However, fatty acid oxidation in adipose tissue is lowered during early lactation, an effect that might be helpful to conserve fatty acids released from adipose tissue for the delivery into other tissues, including mammary gland, via the blood.     

Molecular basis of α1-antitrypsin deficiency revealed by the structure of a domain-swapped trimer

α(1)-Antitrypsin (α1AT) deficiency is a disease with multiple manifestations, including cirrhosis and emphysema, caused by the accumulation of stable polymers of mutant protein in the endoplasmic reticulum of hepatocytes. However, the molecular basis of misfolding and polymerization remain unknown. We produced and crystallized a trimeric form of α1AT that is recognized by an antibody specific for the pathological polymer. Unexpectedly, this structure reveals a polymeric linkage mediated by domain swapping the carboxy-terminal 34 residues. Disulphide-trapping and antibody-binding studies further demonstrate that runaway C-terminal domain swapping, rather than the s4A/s5A domain swap previously proposed, underlies polymerization of the common Z-mutant of α1AT in vivo.     

Differential mesenteric fat deposition in bovines fed on silage or concentrate is independent of glycerol membrane permeability

In the meat industry, the manipulation of fat deposition in cattle is of pivotal importance to improve production efficiency, carcass composition and ultimately meat quality. There is an increasing interest in the identification of key factors and molecular mechanisms responsible for the development of specific fat depots. This study aimed at elucidating the influence of breed and diet on adipose tissue membrane permeability and fluidity and their interplay on fat deposition in bovines. Two Portuguese autochthonous breeds, Alentejana and Barrosã, recognized as late- and early-maturing breeds, respectively, were chosen to examine the effects of breed and diet on fat deposition and on adipose membrane composition and permeability. Twenty-four male bovines from these breeds were fed on silage-based or concentrate-based diets for 11 months. Animals were slaughtered to determine their live slaughter and hot carcass weights, as well as weights of subcutaneous and visceral adipose depots. Mesenteric fat depots were excised and used to isolate adipocyte membrane vesicles where cholesterol content, fatty acid profile as well as permeability and fluidity were determined. Total accumulation of neither subcutaneous nor visceral fat was influenced by breed. In contrast, mesenteric and omental fat depots weights were higher in concentrate-fed bulls relative to silage-fed animals. Membrane fluidity and permeability to water and glycerol in mesenteric adipose tissue were found to be independent of breed and diet. Moreover, the deposition of cholesterol and unsaturated fatty acids, which may influence membrane properties, were unchanged among experimental groups. Adipose membrane lipids from the mesenteric fat depot of ruminants were rich in saturated fatty acids, and unaffected by polyunsaturated fatty acids dietary levels. Our results provide evidence against the involvement of cellular membrane permeability to glycerol on fat accumulation in mesenteric fat tissue of concentrate-fed bovines, which is consistent with the unchanged membrane lipid profile found among experimental groups.     

Astrocyte- and hepatocyte-specific expression of genes from the distal serpin subcluster at 14q32.1 associates with tissue-specific chromatin structures

The distal serpin subcluster contains genes encoding alpha1-antichymotrypsin (ACT), protein C inhibitor (PCI), kallistatin (KAL) and the KAL-like protein, which are expressed in hepatocytes, but only the act gene is expressed in astrocytes. We show here that the tissue-specific expression of these genes associates with astrocyte- and hepatocyte-specific chromatin structures. In hepatocytes, we identified 12 Dnase I-hypersensitive sites (DHSs) that were distributed throughout the entire subcluster, with the promoters of expressed genes accessible to restriction enzyme digestion. In astrocytes, only six DHSs were located exclusively in the 5' flanking region of the act gene, with its promoter also accessible to restriction enzyme digestion. The acetylation of histone H3 and H4 was found throughout the subcluster in both cell types but this acetylation did not correlate with the expression pattern of these serpin genes. Analysis of histone modifications at the promoters of the act and pci genes revealed that methylation of histone H3 on lysine 4 correlated with their expression pattern in both cell types. In addition, inhibition of methyltransferase activity resulted in suppression of ACT and PCI mRNA expression. We propose that lysine 4 methylation of histone H3 correlates with the tissue-specific expression pattern of these serpin genes.     

Interaction of the nuclear localizing cytolytic granule serine protease granzyme B with importin alpha or beta: modulation by the serpin inhibitor PI-9

Conditional on perforin-dependent delivery to the nucleus of target cells, the cytolytic granule serine protease granzyme B (GrB) plays a central role in eliciting the nuclear events of apoptosis, as shown by the fact that reducing GrB nuclear entry prevents nuclear apoptosis. Apart from a requirement for cytosolic factors and lack of dependence on the guanine-nucleotide-binding protein Ran, little is known regarding the nuclear import pathway of GrB. In this study we use quantitative yeast two-hybrid and direct binding assays to show that GrB can be recognized independently by either of the nuclear import receptor family members importin (IMP) alpha and beta1, but that these proteins either alone or in combination cannot replace exogenous cytosol to reconstitute GrB nuclear import in vitro. Whereas antibodies to IMP(alpha) inhibit transport, indicating that IMP(alpha) is required for GrB nuclear import, those to IMP(beta) enhance transport, implying that IMP(beta) inhibits GrB nuclear import; consistent with this, the addition of recombinant IMP(beta) but not IMP(alpha) reduces maximal nuclear accumulation in the presence of cytosol. Intriguingly, complexation of GrB with its specific serpin inhibitor PI-9 was found to prevent recognition by IMP(beta) but not by IMP(alpha), and eliminate the apparent requirement for IMP(alpha) for nuclear import. We conclude that GrB nuclear import exhibits complex regulation by IMPs; that heterodimerization with PI-9 can modulate the interaction has implications for protection against apoptosis.     

Adiponectin expression in human epicardial adipose tissue in vivo is lower in patients with coronary artery disease

BACKGROUND: Intra-peritoneal adipose tissue is recognized as a predictor of metabolic syndrome and may contribute to the risk for cardiovascular disease by the production of adipocytokines, including adiponectin. Nevertheless, there is no knowledge on whether other visceral depots of adipose tissue, including the epicardial fat, have any metabolically active role, including production of adiponectin. AIM OF THE STUDY: We sought to evaluate adiponectin protein expression in epicardial adipose tissue in vivo both in patients with severe coronary artery disease (CAD) and in subjects without CAD. METHODS: Twenty-two patients were enrolled for the study. We selected 16 patients who underwent elective coronary artery bypass graft surgery for critical CAD, 5 who underwent surgery for valve replacement and 1 for correction of an interatrial defect. Epicardial adipose tissue biopsy samples were obtained before the initiation of cardiopulmonary bypass. Adiponectin protein level in epicardial adipose tissue was evaluated by Western blotting. RESULTS: Adiponectin protein value, expressed as adiponectin/actin ratio, in epicardial adipose tissue was significantly lower in patients with severe CAD than in those without CAD (1.42 +/- 0.77 vs 2.36 +/- 0.84 p = 0.02, 95% CI 0.64-1.74). CONCLUSIONS: This study showed for the first time that human epicardial adipose tissue expresses adiponectin. Adiponectin expression is significantly lower in epicardial fat isolated from patients with CAD.