SIRT1 Limits Adipocyte Hyperplasia through c-Myc Inhibition

The expansion of fat mass in the obese state is due to increased adipocyte hypertrophy and hyperplasia. The molecular mechanism that drives adipocyte hyperplasia remains unknown. The NAD⁺-dependent protein deacetylase sirtuin 1 (SIRT1), a key regulator of mammalian metabolism, maintains proper metabolic functions in many tissues, counteracting obesity. Here we report that differentiated adipocytes are hyperplastic when SIRT1 is knocked down stably in mouse 3T3-L1 preadipocytes. This phenotype is associated with dysregulated adipocyte metabolism and enhanced inflammation. We also demonstrate that SIRT1 is a key regulator of proliferation in preadipocytes. Quantitative proteomics reveal that the c-Myc pathway is altered to drive enhanced proliferation in SIRT1-silenced 3T3-L1 cells. Moreover, c-Myc is hyperacetylated, levels of p27 are reduced, and cyclin-dependent kinase 2 (CDK2) is activated upon SIRT1 reduction. Remarkably, differentiating SIRT1-silenced preadipocytes exhibit enhanced mitotic clonal expansion accompanied by reduced levels of p27 as well as elevated levels of CCAAT/enhancer-binding protein β (C/EBPβ) and c-Myc, which is also hyperacetylated. c-Myc activation and enhanced proliferation phenotype are also found to be SIRT1-dependent in proliferating mouse embryonic fibroblasts and differentiating human SW872 preadipocytes. Reducing both SIRT1 and c-Myc expression in 3T3-L1 cells simultaneously does not induce the adipocyte hyperplasia phenotype, confirming that SIRT1 controls adipocyte hyperplasia through c-Myc regulation. A better understanding of the molecular mechanisms of adipocyte hyperplasia will open new avenues toward understanding obesity.     

Perceptions and Attitudes towards Medical Research in the United Arab Emirates: Results from the Abu Dhabi Cohort Study (ADCS) Focus Group Discussions

Background

In developing medical research, particularly in regions where medical research is largely unfamiliar, it is important to understand public perceptions and attitudes towards medical research. In preparation for starting the first cohort study in the United Arab Emirates, the Abu Dhabi Cohort Study (ADCS), we sought to understand how we could improve the quality of the research process for participants and increase public trust and awareness of research.

Methods

We conducted six focus groups (FG), consisting of Emirati men and women aged above 18 years to resemble the target population for the ADCS. Sampling was purposive and convenient. Data collection was an iterative process until saturation was reached with no new themes identified. Text from each FG was analyzed separately by identifying emerging issues and organizing related concepts into categories or themes. A coding tree was developed, consisting of the main concepts, themes, subthemes and corresponding quotes. Both themes and main ideas were identified using inductive analysis.

Results

Forty-two participants enrolled at 3 academic centers (New York University Abu Dhabi, UAE University, Zayed University) and the Abu Dhabi blood bank. Focus group participants described lack of awareness of research as a challenge to participation in clinical research studies. Altruism, personal relevance of the research, and the use of role models were commonly identified motivators. Participants were generally satisfied with the informed consent process for the ADCS, but would be disappointed if not provided test results or study outcomes. Fear of a breach in confidentiality was a frequently expressed concern.

Conclusions

Participants join research studies for varied, complex reasons, notably altruism and personal relevance. Based on these insights, we propose specific actions to enhance participant recruitment, retention and satisfaction in the ADCS. We identified opportunities to improve the research experience through improved study materials and communication to participants and the broader community.     

An Anti-β-Amyloid Vaccine for Treating Cognitive Deficits in a Mouse Model of Down Syndrome

In Down syndrome (DS) or trisomy of chromosome 21, the β-amyloid (Aβ) peptide product of the amyloid precursor protein (APP) is present in excess. Evidence points to increased APP gene dose and Aβ as playing a critical role in cognitive difficulties experienced by people with DS. Particularly, Aβ is linked to the late-life emergence of dementia as associated with neuropathological markers of Alzheimer’s disease (AD). At present, no treatment targets Aβ–related pathogenesis in people with DS. Herein we used a vaccine containing the Aβ 1–15 peptide embedded into liposomes together with the adjuvant monophosphoryl lipid A (MPLA). Ts65Dn mice, a model of DS, were immunized with the anti-Aβ vaccine at 5 months of age and were examined for cognitive measures at 8 months of age. The status of basal forebrain cholinergic neurons and brain levels of APP and its proteolytic products were measured. Immunization of Ts65Dn mice resulted in robust anti-Aβ IgG titers, demonstrating the ability of the vaccine to break self-tolerance. The vaccine-induced antibodies reacted with Aβ without detectable binding to either APP or its C-terminal fragments. Vaccination of Ts65Dn mice resulted in a modest, but non-significant reduction in brain Aβ levels relative to vehicle-treated Ts65Dn mice, resulting in similar levels of Aβ as diploid (2N) mice. Importantly, vaccinated Ts65Dn mice showed resolution of memory deficits in the novel object recognition and contextual fear conditioning tests, as well as reduction of cholinergic neuron atrophy. No treatment adverse effects were observed; vaccine did not result in inflammation, cellular infiltration, or hemorrhage. These data are the first to show that an anti-Aβ immunotherapeutic approach may act to target Aβ-related pathology in a mouse model of DS.     

Communities of culturable yeasts and yeast-like fungi in oligotrophic hypersaline coastal waters of the Arabian Gulf surrounding Qatar

This report is the first investigation of yeast biodiversity from the oligotrophic hypersaline coastal waters of the Arabian Gulf surrounding Qatar. Yeasts and yeast-like fungi, were cultured from seawater sampled at 13 coastal areas surrounding Qatar over a period of 2 years (December 2013–September 2015). Eight hundred and forty-two isolates belonging to 82 species representing two phyla viz., Ascomycota (23 genera) and Basidiomycota (16 genera) were identified by molecular sequencing. The results indicated that the coastal waters of the Qatari oligotrophic marine environment harbor a diverse pool of yeast species, most of which have been reported from terrestrial, clinical and aquatic sources in various parts of the world. Five species, i.e., Candida albicans, C. parapsilosis, C. tropicalis, Pichia kudriavzevii and Meyerozyma guilliermondii (n?=?252/842; 30% isolates) are known as major opportunistic human pathogens. Fifteen species belonging to nine genera (n?=?498/842; 59%) and 12 species belonging to seven genera (n?=?459/842; 55%) are hydrocarbon degrading yeast and pollution indicator yeast species, respectively. Ascomycetous yeasts were predominant (66.38%; 559/842) as compared to their basidiomycetous counterparts (33.6%; 283/842). The most isolated yeast genera were Candida (28%; 236/842) (e.g., C. aaseri, C. boidinii, C. glabrata, C. intermedia, C. oleophila, C. orthopsilosis, C. palmioleophila, C. parapsilosis, C. pseudointermedia, C. rugopelliculosa, C. sake, C. tropicalis and C. zeylanoides), Rhodotorula (12.7%; 107/842), Naganishia (8.4%; 71/842), Aureobasidium (7.4%; 62/842), Pichia (7.3%; 62/842), and Debaryomyces (6.4%; 54/842). A total of eleven yeast species ( n = 38) isolated in this study are reported for the first time from the marine environment. Chemical testing demonstrated that seven out of the 13 sites had levels of total petroleum hydrocarbons (TPH) ranging from 200 to 900 µg/L, whereas 6 sites showed higher TPH levels (>?1000–21000 µg/L). The results suggest that the yeast community structure and density are impacted by various physico-chemical factors, namely total organic carbon, dissolved organic carbon and sulphur.

     

Structural,morphological and steady state photoluminescence spectroscopy studies of red Eu3+‐doped Y2O3 nanophosphors prepared by the sol‐gel method

Europium trivalent (Eu³⁺)‐doped Y₂O₃ nanopowders of different concentrations (0.5, 2.5, 5 or 7 at.%) were synthesized by the sol‐gel method, at different pH values (pH 2, 5 or 8) and annealing temperatures (600°C, 800°C or 1000°C). The nanopowders samples were characterized by X‐ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM), Fourier transform infrared spectroscopy (FT‐IR) and steady state photoluminescence spectroscopy. The effect of pH of solution and annealing temperatures on structural, morphological and photoluminescence properties of Eu³⁺‐doped Y₂O₃ were studied and are discussed. It was found that the average crystallite size of the nanopowders increased with increasing pH and annealing temperature values. The Y₂O₃:Eu³⁺ material presented different morphology and its evolution depended on the pH value and the annealing temperature. Activation energies at different pH values were determined and are discussed. Under ultraviolet (UV) light excitation, Y₂O₃:Eu³⁺ showed narrow emission peaks corresponding to the ⁵D_0–⁷F_J (J = 0, 1, 2 and 3) transitions of the Eu³⁺ ion, with the most intense red emission at 611 assigned to forced electric dipole ⁵D₀→⁷F₂. The emission intensity became more intense with increasing annealing temperature and pH values, related to the improvement of crystalline quality. For the 1000°C annealing temperature, the emission intensity presented a maximum at pH 5 related to the uniform cubic‐shaped particles. It was found that for lower annealing temperatures (small crystallite size) the CTB (charge transfer band) position presented a red shift. Copyright © 2015 John Wiley & Sons, Ltd.     

14-3-3? and 14-3-3σ Inhibit Toll-like Receptor (TLR)-mediated Proinflammatory Cytokine Induction

Toll-like receptors (TLRs) are a group of pattern recognition receptors that play a crucial role in the induction of the innate immune response against bacterial and viral infections. TLR3 has emerged as a key sensor of viral double-stranded RNA. Thus, a clearer understanding of the biological processes that modulate TLR3 signaling is essential. Limited studies have applied proteomics toward understanding the dynamics of TLR signaling. Herein, a proteomics approach identified 14-3-3ϵ and 14-3-3σ proteins as new members of the TLR signaling complex. Toward the functional characterization of 14-3-3ϵ and 14-3-3σ in TLR signaling, we have shown that both of these proteins impair TLR2, TLR3, TLR4, TLR7/8, and TLR9 ligand-induced IL-6, TNFα, and IFN-β production. We also show that 14-3-3ϵ and 14-3-3σ impair TLR2-, TLR3-, TLR4-, TLR7/8-, and TLR9-mediated NF-κB and IFN-β reporter gene activity. Interestingly, although the 14-3-3 proteins inhibit poly(I:C)-mediated RANTES production, 14-3-3 proteins augment Pam₃CSK₄, LPS, R848, and CpG-mediated production of RANTES (regulated on activation normal T cell expressed and secreted) in a Mal (MyD88 adaptor-like)/MyD88-dependent manner. 14-3-3ϵ and 14-3-3σ also bind to the TLR adaptors and to both TRAF3 and TRAF6. Our study conclusively shows that 14-3-3ϵ and 14-3-3σ play a major regulatory role in balancing the host inflammatory response to viral and bacterial infections through modulation of the TLR signaling pathway. Thus, manipulation of 14-3-3 proteins may represent novel therapeutic targets for inflammatory conditions and infections.