Identification of an AAA ATPase VPS4B-dependent pathway that modulates epidermal growth factor receptor abundance and signaling during hypoxia

VPS4B, an AAA ATPase (ATPase associated with various cellular activities), participates in vesicular trafficking and autophagosome maturation in mammalian cells. In solid tumors, hypoxia is a common feature and an indicator of poor treatment outcome. Our studies demonstrate that exogenous or endogenous (assessed with anchorage-independent three-dimensional multicellular spheroid culture) hypoxia induces VPS4B downregulation by the ubiquitin-proteasome system. Inhibition of VPS4B function by short hairpin VPS4B (sh-VPS4B) or expression of dominant negative VPS4B(E235Q) promotes anchorage-independent breast cancer cell growth and resistance to gefitinib, U0126, and genotoxicity. Biochemically, hyperactivation of epidermal growth factor receptor (EGFR), a receptor tyrosine kinase essential for cell proliferation and survival, accompanied by increased EGFR accumulation and altered intracellular compartmentalization, is observed in cells with compromised VPS4B. Furthermore, enhanced FOS/JUN induction and AP-1 promoter activation are noted in EGF-treated cells with VPS4B knockdown. However, VPS4B depletion does not affect EGFRvIII stability or its associated signaling. An inverse correlation between VPS4B expression and EGFR abundance is observed in breast tumors, and high-grade or recurrent breast carcinomas exhibit lower VPS4B expression. Together, our findings highlight a potentially critical role of VPS4B downregulation or chronic-hypoxia-induced VPS4B degradation in promoting tumor progression, unveiling a nongenomic mechanism for EGFR overproduction in human breast cancer.     

Cockroach wings-promoted safe and greener synthesis of silver nanoparticles and their insecticidal activity

Bioprocess and Biosystems Engineering - Simpler and biocompatible greener approaches for the assembly of nanoparticles (NPs) have been the focus lately which have minimum environmental damage and...     

The glycophosphatidylinositol anchor oppositely affects unfolding and refolding of alkaline phosphatase

Regarding the world wide success of artificial chaperone-assisted protein refolding technique and based on its well worked-out mechanism, it is anticipated that the lipid moieties of glycosylphosphatidylinositol (GPI) group, which is present in some membrane proteins, might interfere with the capturing step of the technique. To find an answer, we evaluated the chemical denaturation and also the refolding behavior of insoluble and soluble alkaline phosohatase (ALP), with or without GPI group, respectively. The results indicated that the presence of GPI in the enzyme increased the stability of the protein against chemical denaturation while it decreased its refolding yield by the artificial chaperone refolding technique. The lower refolding yield, compared to soluble ALP (sALP), might be due to a less efficient stripping step caused by new interactions imparted to the refolding elements of the system especially those among the hydrophobic tails of GPI and the capturing agent of the technique. These new interactions will interrupt the kinetics of detergent stripping from the captured molecules by the stripping agent (i.e., cyclodextrins). This situation will lead to higher intermolecular hydrophobic interactions among the refolding protein intermediates leading to their higher misfolding and aggregation.     

Morphological and Physical Analysis of Natural Phospholipids-Based Biomembranes

Background

Liposomes are currently an important part of biological, pharmaceutical, medical and nutritional research, as they are considered to be among the most effective carriers for the introduction of various types of bioactive agents into target cells.

Scope of Review

In this work, we study the lipid organization and mechanical properties of biomembranes made of marine and plant phospholipids. Membranes based on phospholipids extracted from rapeseed and salmon are studied in the form of liposome and as supported lipid bilayer. Dioleylphosphatidylcholine (DOPC) and dipalmitoylphosphatidylcholine (DPPC) are used as references to determine the lipid organization of marine and plant phospholipid based membranes. Atomic force microscopy (AFM) imaging and force spectroscopy measurements are performed to investigate the membranes'' topography at the micrometer scale and to determine their mechanical properties.

Major Conclusions

The mechanical properties of the membranes are correlated to the fatty acid composition, the morphology, the electrophoretic mobility and the membrane fluidity. Thus, soft and homogeneous mechanical properties are evidenced for salmon phospholipids membrane containing various polyunsaturated fatty acids. Besides, phase segregation in rapeseed membrane and more important mechanical properties were emphasized for this type of membranes by contrast to the marine phospholipids based membranes.

General Significance

This paper provides new information on the nanomechanical and morphological properties of membrane in form of liposome by AFM. The originality of this work is to characterize the physico-chemical properties of the nanoliposome from the natural sources containing various fatty acids and polar head.     

Morphine-Induced Apoptosis in the Ventral Tegmental Area and Hippocampus After the Development but not Extinction of Reward-Related Behaviors in Rats

Some data suggest that morphine induces apoptosis in neurons, while other evidences show that morphine could have protective effects against cell death. In this study, we suggested that there is a parallel role of morphine in reward circuitry and apoptosis processing. Therefore, we investigated the effect of morphine on modifications of apoptotic factors in the ventral tegmental area (VTA) and hippocampus (HPC) which are involved in the reward circuitry after the acquisition and extinction periods of conditioned place preference (CPP). In behavioral experiments, different doses of morphine (0.5, 5, and 10 mg/kg) and saline were examined in the CPP paradigm. Conditioning score and locomotor activity were recorded by Ethovision software after acquisition on the post-conditioning day, and days 4 and 8 of extinction periods. In order to investigate the molecular mechanisms in each group, we then dissected the brains and measured the expression of apoptotic factors in the VTA and HPC by western blotting analysis. All of the morphine-treated groups showed an increase of apoptotic factors in these regions during acquisition but not in extinction period. In the HPC, morphine significantly increased the ratio of Bax/Bcl-2, caspases-3, and PARP by the lowest dose (0.5 mg/kg), but, in the VTA, a considerable increase was seen in the dose of 5 mg/kg; promotion of apoptotic factors in the HPC and VTA insinuates that morphine can affect the molecular mechanisms that interfere with apoptosis through different receptors. Our findings suggest that a specific opioid receptor involves in modification of apoptotic factors expression in these areas. It seems that the reduction of cell death in response to high dose of morphine in the VTA and HPC may be due to activation of low affinity opioid receptors which are involved in neuroprotective features of morphine.     

Interleukin-6 gene polymorphism -174G/C influences plasma lipid levels in women

Elevated levels of the pro-inflammatory cytokine interleukin-6 (IL-6) have been associated with cardiovascular risk factors. The objective of this study was to investigate potential associations between the promoter polymorphism IL-6 -174G/C and the following indices of metabolism: BMI, waist-to-hip ratio, and plasma levels of IL-6, cholesterol, low-density lipoprotein, triglycerides, high-density lipoprotein, leptin, and C-reactive protein in 252 42-year-old women and 245 51-year-old men. Subgroups were also studied 5 years later. The CC genotype of the IL-6 polymorphism was associated with lower levels of cholesterol and low-density lipoprotein (p < 0.001) in women. This finding was replicated in the follow-up, when a significant association between the CC genotype and low triglycerides was also observed. The association between the C allele and lipid pattern found in women was not found in men, where on the contrary, C carriers tended to display elevated triglycerides. IL-6 genotype was not associated with IL-6 plasma levels in either sample. The results suggest different effects of the IL-6 polymorphism on metabolic indices in women and men. None of the associations between IL-6 genotype and lipid pattern seemed to result from an effect of the polymorphism on IL-6 plasma levels.     

Biogenesis of lipid droplets--how cells get fatter

Lipid droplets are discrete organelles present in most cell types and organisms including bacteria, yeast, plants, insects and animals. Long considered as passive storage deposits, recent cell biology, proteomic and lipidomic analysis show that lipid droplets are dynamic organelles involved in multiple cellular functions. They have a central function in lipid distribution to different membrane-bound organelles and serve not only as main reservoirs of neutral lipids such as triglycerides and cholesterol but in addition, contain structural proteins, proteins involved in lipid synthesis and transmembrane proteins. A detailed model for how transmembrane proteins such as SNARE proteins can exist in lipid droplets is proposed.     

Association between the AGTR1 polymorphism +1166A>C and serum levels of high-sensitivity C-reactive protein

Genetic factors have been shown to influence high-sensitivity C-reactive protein (hsCRP) levels, however, which genes that are involved in this process remains to be clarified. The renin–angiotensin system (RAS) is of importance for the regulation of inflammation, and blockade of angiotensin II type 1 receptors (AGTR1) influences hsCRP levels. These findings prompted us to investigate whether a polymorphism in the AGTR1 gene may influence hsCRP levels. Additionally, a polymorphism in the CRP gene that has previously been shown to influence hsCRP levels was genotyped. Serum levels of hsCRP were measured in 270 42-year-old women recruited from the population registry. Two single nucleotide polymorphisms were analysed: +1166A>C and +1444C>T of the AGTR1 and CRP gene, respectively. The A allele of the AGTR1 polymorphism +1166A>C was dose-dependently associated with higher hsCRP levels (p = 0.014, adjusted for confounding factors and multiple comparisons). hsCRP levels were not significantly influenced by the CRP +1444C>T genotype; however, an interaction between the two studied polymorphisms with respect to hsCRP levels was observed (p = 0.018). The significant association between the AGTR1 polymorphism and hsCRP levels, which appears to be independent of anthropometric and metabolic traits, is yet another indication of a direct influence of RAS on inflammation.     

Designing a Highly Efficient Chemical Chaperone System Using Chitosan-Coated Alginate

In the present work we prepared chitosan-coated alginate beads, to use as a chemical chaperone based on the electrostatic interaction between the carboxylate groups of alginate and the ammonium groups of chitosan. This procedure was an attempt for designing a highly efficient chemical chaperone to improve protein stability and refolding. Based on enzyme recovered activity, turbidity, far-UV CD and fluorescence data, alkaline phosphatase can be stabilized and refolded to a higher degree in the presence of alginate capsules compared with unassisted form and was further improved by including chitosan. Finally the maximum yield was obtained when the refolding process was achieved under a well worked out temperature program: incubation of the captured-enzyme for 20 min at 4 °C followed by overnight incubation at 22 °C, which showed that aggregation is a major limitation to refolding.     

The Lean Woman

Objective: In the current obesity epidemic, the ability to remain lean is beginning to be uncommon. Therefore, it was considered of interest to characterize such subjects. Research Methods and Procedures: From a population of premenopausal women (n = 270), all 40 years of age, those with a similar body mass index (BMI) as women at the age of 21 years, born the same year (BMI = 21.1 kg/m²) were selected among nonsmokers and compared with the remaining nonsmoking women. Results: Lean women showed, as expected, low waist-to-hip circumference ratio and abdominal sagittal diameter as well as absence of other disease risk factors. Compared with the remaining women, 17β-estradiol was high and androgens were low, whereas insulin-like growth factor I and thyroid hormones showed no differences. Dihydroepiandrosterone sulfate was lower, whereas cortisol, measured in saliva repeatedly over a day, and adrenocorticotropin hormone were not different. Results from questionnaires indicated higher education and socioeconomic status, frequent sports activities, and better psychosocial adaptation and psychological health. A tetranucleotide repeat polymorphism in the fifth intron of the aromatase P450 gene was longer among the lean (187 base pairs) than the rest of the women. Women with opposite phylogenetic characteristic have a short microsatellite (168 base pairs) in this gene locus. Discussion: Lean, nonsmoking women enjoy an excellent health in not only anthropometric and metabolic factors, but also in neuroendocrine, endocrine, and psychological variables. The endocrine measurements suggest a well-functioning aromatase, which in turn might have a genetic background, contributing to health. The aromatase gene might be important for regulation of body fat mass.