Genetic meta-analysis of 15,901 African Americans identifies variation in EXOC3L1 is associated with HDL concentration

Meta-analyses of European populations has successfully identified genetic variants in over 150 loci associated with lipid levels, but results from additional ethnicities remain limited. Previously, we reported two novel lipid loci identified in a sample of 7,657 African Americans using a gene-centric array including 50,000 SNPs in 2,100 candidate genes. Initial discovery and follow-up of signals with P < 10⁻⁵ in additional African American samples confirmed CD36 and ICAM1. Using an additional 8,244 African American female samples from the Women’s Health Initiative SNP Health Association Resource genome-wide association study dataset, we further examined the previous meta-analyses results by attempting to replicate 20 additional putative lipid signals with P < 10⁻⁴. Replication confirmed rs868213, located in a splice donor region of exocyst complex component 3-like 1 (EXOC3L1) as a novel signal for HDL (additive allelic effect β = 0.02; P = 1.4 × 10⁻⁸; meta-analyses of discovery and replication). EXOC3L1 is strongly expressed in vascular endothelium and forms part of the exocyst complex, a key facilitator of the trafficking of lipid receptors. Increasing sample sizes for genetic studies in nonEuropean populations will continue to improve our understanding of lipid metabolism.     

Down‐regulation of mitogen‐activated protein kinases and nuclear factor‐κB signaling is involved in rapamycin suppression of TLR2‐induced inflammatory response in monocytic THP‐1 cells

Tripalmitoyl‐S‐glycero‐Cys‐(Lys) 4 (Pam3CSK4) interacted with TLR2 induces inflammatory responses through the mitogen‐activated protein kinases (MAPKs) and nuclear factor‐κB (NF‐κB) signal pathway. Rapamycin can suppress TLR‐induced inflammatory responses; however, the detailed molecular mechanism is not fully understood. Here, the mechanism by which rapamycin suppresses TLR2‐induced inflammatory responses was investigated. It was found that Pam3CSK4‐induced pro‐inflammatory cytokines were significantly down‐regulated at both the mRNA and protein levels in THP‐1 cells pre‐treated with various concentrations of rapamycin. Inhibition of phosphatidylinositol 3‐kinase/protein kinase‐B (PI3K/AKT) signaling did not suppress the expression of pro‐inflammatory cytokines, indicating that the immunosuppression mediated by rapamycin in THP1 cells is independent of the PI3K/AKT pathway. RT‐PCR showed that Erk and NF‐κB signal pathways are related to the production of pro‐inflammatory cytokines. Inhibition of Erk or NF‐κB signaling significantly down‐regulated production of pro‐inflammatory cytokines. Additionally, western blot showed that pre‐treatment of THP‐1 cells with rapamycin down‐regulates MAPKs and NF‐κB signaling induced by Pam3CSK4 stimulation, suggesting that rapamycin suppresses Pam3CSK4‐induced pro‐inflammatory cytokines via inhibition of TLR2 signaling. It was concluded that rapamycin suppresses TLR2‐induced inflammatory responses by down‐regulation of Erk and NF‐κB signaling.     

The diagnostic potential of MPT63‐derived HLA‐A*0201‐restricted CD8+T‐cell epitopes for active pulmonary tuberculosis

MPT63 protein is found only in Mycobacterium tuberculosis complex, including M. tuberculosis and M. bovis. Detection of MPT63‐specific IFN‐γ‐secreting T cells could be useful for the diagnosis of tuberculosis (TB) diseases. In the present study, the HLA‐A*0201 restriction of ten predicted MPT63‐derived CD8 ⁺ T‐cell epitopes was assessed on the basis of T2 cell line and HLA‐A*0201 transgenic mice. The diagnostic potential of immunogenic peptides in active pulmonary TB patients was evaluated using an IFN‐γ enzyme‐linked immunospot assay. It was found that five peptides bound to HLA‐A*0201 with high affinity, whereas the remaining peptides exhibited low affinity for HLA‐A*0201. Five immunogenic peptides (MPT63_18–26, MPT63_29–37, MPT63_20–28, MPT63_5–14 and MPT63_10–19) elicited large numbers of cytotoxic IFN‐γ‐secreting T cells in HLA‐A*0201 transgenic mice. Each of the five immunogenic peptides was recognized by peripheral blood mononuclear cells from 45% to 73% of 40 HLA‐A*0201 positive TB patients. The total diagnostic sensitivity of the five immunogenic peptides was higher than that of a T‐SPOT.TB assay (based on ESAT‐6 and CFP‐10) (93% versus 90%). It is noticeable that the diagnostic sensitivity of the combination of five immunogenic peptides and T‐SPOT.TB assay reached 100%. These MPT63‐derived HLA‐A*0201‐restricted CD8 ⁺ T‐cell epitopes would likely contribute to the immunological diagnosis of M. tuberculosis infection and may provide the components for designing an effective TB vaccine.     

Frequent Unanticipated Alleles of lethal giant larvae in Drosophila Second Chromosome Stocks

Forty years ago, a high frequency of lethal giant larvae (lgl) alleles in wild populations of Drosophila melanogaster was reported. This locus has been intensively studied for its roles in epithelial polarity, asymmetric neural divisions, and restriction of tissue proliferation. Here, we identify a high frequency of lgl alleles in the Bloomington second chromosome deficiency kit and the University of California at Los Angeles Bruinfly FRT40A-lethal P collection. These unrecognized aberrations confound the use of these workhorse collections for phenotypic screening or genetic mapping. In addition, we determined that independent alleles of insensitive, reported to affect asymmetric cell divisions during sensory organ development, carry lgl deletions that are responsible for the observed phenotypes. Taken together, these results encourage the routine testing of second chromosome stocks for second-site alleles of lgl.     

GST pull-down验证流感病毒PB1-F2蛋白与热休克蛋白40的相互作用

为体外验证流感病毒PB1-F2与热休克蛋白Hsp40相互作用,通过两个方向的GST pull-down试验验证PB1-F2与Hsp40的相互作用。构建GST-多肽融合蛋白原核表达载体pGEX-6P-1-PB1-F2和pGEX-6P-1-Hsp40,并在大肠杆菌(E.co-li)BL21中诱导表达;构建真核表达载体pLEGFP-Hsp40及pCAGGS-PB1-F2,并分别转染293T细胞使其表达Hsp40及PB1-F2融合蛋白,然后进行GST pull-down试验验证二者的相互作用。成功地构建了两种蛋白的各种表达载体,经表达、纯化获得了可溶性的GST-多肽融合蛋白,GST pull-down试验正反两方向都证实了PB1-F2与Hsp40的相互作用,初步证实了流感病毒PB1-F2在体外能与Hsp40发生相互作用。     

Adaptability to elevated temperature and nitrogen addition is greater in a high-elevation population than in a low-elevation population of Hippophae rhamnoides

Hippophae rhamnoides L. is a broadleaf deciduous woody shrub occurring in southwest China, where it has been widely used in ecological restoration. In this study we investigated growth and physiological responses of 2-year-old healthy seedlings to elevated temperature, nitrogen (N) addition and their combination in two contrasting populations from high and low elevations. In closed-top chamber experiments, two populations were subjected to two temperature conditions (ambient temperature and temperature elevated by 2.2 ± 0.2°C) and two N levels (0 and 25 g N m⁻² a⁻¹). Compared with the control, increases in total leaf area (TLA), total chlorophyll content (TC), light-saturated photosynthetic rate (P _max), guaiacol peroxidase activity (POD), catalase activity (CAT) and carbon isotope composition (δ¹³C) were greater in the high-elevation population than in the low-elevation population under elevated temperature. On the other hand, decreases in root and shoot biomass ratio (RS), TC, P _max, light saturation point (L _SP), light compensation point (L _CP), superoxide dismutase (SOD), POD, CAT and δ¹³C were lower in the high-elevation population than in the low-elevation population under N addition. Moreover, the combination of elevated temperature and N addition decreased RS, P _max, apparent quantum efficiency (Φ), SOD, POD and δ¹³C significantly more in the low-elevation population than in the high-elevation population. These results demonstrated that there are different adaptive strategies among H. rhamnoides populations, the high-elevation population exhibiting higher adaptability to elevated temperature and N addition than the low-elevation population.     

Alzheimer's Disease Drug Candidates Stabilize A-β Protein Native Structure by Interacting with the Hydrophobic Core

Deposition of amyloid fibrils, consisting primarily of Aβ₄₀ and Aβ₄₂ peptides, in the extracellular space in the brain is a major characteristic of Alzheimer's disease (AD). We recently developed new (to our knowledge) drug candidates for AD that inhibit the fibril formation of Aβ peptides and eliminate their neurotoxicity. We performed all-atom molecular-dynamics simulations on the Aβ₄₂ monomer at its α-helical conformation and a pentamer fibril fragment of Aβ₄₂ peptide with or without LRL and fluorene series compounds to investigate the mechanism of inhibition. The results show that the active drug candidates, LRL22 (EC₅₀ = 0.734 μM) and K162 (EC₅₀ = 0.080 μM), stabilize hydrophobic core I of Aβ₄₂ peptide (residues 17–21) to its α-helical conformation by interacting specifically in this region. The nonactive drug candidates, LRL27 (EC₅₀ > 10 μM) and K182 (EC₅₀ > 5 μM), have little to no similar effect. This explains the different behavior of the drug candidates in experiments. Of more importance, this phenomenon indicates that hydrophobic core I of the Aβ₄₂ peptide plays a major mechanistic role in the formation of amyloid fibrils, and paves the way for the development of new drugs against AD.