Molecular modeling on HIF2α-ARNT dimer destabilization caused by HIF2α V192D and/or R171A mutations

The hypoxia-inducible-factors (HIFs) are responsible for cellular adaptations to low oxygen stress by activating transcriptional programs such as erythropoiesis and angiogenesis. Because these programs are related to tumor growth and progression, HIFs have become attractive targets for cancer therapy. To function as oxygen-sensitive regulatory subunits, HIF2α must form a heterodimer with the aryl hydrocarbon receptor nuclear translocator (ARNT). Both HIF and ARNT proteins have a basic-helix-loop-helix (bHLH) domain for DNA reading in their amino-termini, followed by two tandem Per-ARNT-Sim (PAS) domain, namely PAS-A and PAS-B, for HIF-ARNT dimerization, and transactivation domains (TAD) in their carboxyl-termini. According to the recently solved HIF2α-ARNT dimer structure (not covering their TADs), there are six domain-domain interfaces including HIF2α’s bHLH with ARNT’s bHLH, HIF2α’s PAS-A with ARNT’s PAS-A, HIF2α’s PAS-B with ARNT’s PAS-A, HIF2α’s PAS-B with ARNT’s PAS-B, HIF2α’s PAS-A with HIF2α’s PAS-B, and HIF2α’s bHLH with HIF2α’s PAS-B. Structural comparison shows that HIF2α’s bHLH, PAS-A, and PAS-B domains are compactly interconnected; whereas ARNT’s bHLH, PAS-A, and PAS-B domains are linked by long flexible loops to grant structural adaptability to dimerize different bHLH-PAS proteins members. Lately, co-immunoprecipitation experiments have shown that R171A and/or V192D on HIF2α’s PAS-A domain impair HIF2α-ARNT dimerization. Herein we applied molecular dynamics simulations to investigate the structural and dynamic impact brought by these mutations. Our results conclude that these mutated amino residues, located in HIF2α’s PAS-A with HIF2α’s PAS-B interface, change the relative orientation and motion of PAS-A and PAS-B and therefore these two PAS domains are not recognizable by ARNT

Doping and temperature dependence of electron spectrum and quasiparticle dispersion in doped bilayer cuprates

Within the t-t'-J model, the electron spectrum and quasiparticle dispersion in doped bilayer cuprates in the normal state are discussed by considering the bilayer interaction. It is shown that the bilayer interaction splits the electron spectrum of doped bilayer cuprates into the bonding and antibonding components around the $(\pi,0)$ point. The differentiation between the bonding and antibonding components is essential, which leads to two main flat bands around the $(\pi,0)$ point below the Fermi energy. In analogy to the doped single layer cuprates, the lowest energy states in doped bilayer cuprates are located at the $(\pi/2,\pi/2)$ point. Our results also show that the striking behavior of the electronic structure in doped bilayer cuprates is intriguingly related to the bilayer interaction together with strong coupling between the electron quasiparticles and collective magnetic excitations.Comment: 9 pages, 4 figures, updated references, added figures and discussions, accepted for publication in Phys. Rev.

Branched actin networks are assembled on microtubules by adenomatous polyposis coli for targeted membrane protrusion

Cell migration is driven by pushing and pulling activities of the actin cytoskeleton, but migration directionality is largely controlled by microtubules. This function of microtubules is especially critical for neuron navigation. However, the underlying mechanisms are poorly understood. Here we show that branched actin filament networks, the main pushing machinery in cells, grow directly from microtubule tips toward the leading edge in growth cones of hippocampal neurons. Adenomatous polyposis coli (APC), a protein with both tumor suppressor and cytoskeletal functions, concentrates at the microtubule-branched network interface, whereas APC knockdown nearly eliminates branched actin in growth cones and prevents growth cone recovery after repellent-induced collapse. Conversely, encounters of dynamic APC-positive microtubule tips with the cell edge induce local actin-rich protrusions. Together, we reveal a novel mechanism of cell navigation involving APC-dependent assembly of branched actin networks on microtubule tips

Heart Failure Direct Renin Inhibitor Attenuates Left Ventricular Remodeling in Post-Myocardial Infarction Heart Failure Mice

Background: The role of direct renin inhibitors in myocardial ischemia-induced heart failure is controversial. We hypothesized that direct renin inhibitors play a positive role, affecting in vivo myocardial function as well as in vitro extracellular matrix change. Methods: Ten-week-old C57BL/6J male mice with 2-kidney 1-clip (2K1C) model were enrolled in this study. The mice were divided into 3 groups each with 18 mice; group 1 sham-operated, group 2 coronary artery ligationinduced heart failure, and group 3 coronary artery ligation-induced heart failure receiving aliskiren minipump infusion. These mice were assessed for systemic hemodynamics and left ventricular function by 2-dimensional echocardiography (iE33, Philips). Myocardial tissue was stained and crude protein was isolated from the nonischemic viable left ventricle. Myocardial tissue contents of anti-angiotensin II type 1 (AT1) receptor, matrix metalloproteinase (MMP)-2 and MMP-9 were examined. Results: There were 54 mice that received 2K1C and were followed up for three weeks. Baseline characteristics showed no difference. At follow-up, the heart failure-only group had greater left ventricular mass and worse systolic function as compared to the sham group. Whereas the heart failure-aliskiren group had lower left ventricle mass and better systolic function as compared to the heart failure-only group. AT1 receptor, MMP-2 and MMP-9 levels were increased in the heart failure-only model while direct renin inhibitor attenuated this significantly. Conclusions: Direct renin inhibitors improved myocardial function in a myocardial ischemia-induced heart failure mouse model. The improvement seen is present in myocardial mass, left ventricular systolic function and also in myocardial interstitial tissue

Genomics and proteomics of immune modulatory effects of a butanol fraction of echinacea purpurea in human dendritic cells

<p>Abstract</p> <p>Background</p> <p><it>Echinacea </it>spp. extracts and the derived phytocompounds have been shown to induce specific immune cell activities and are popularly used as food supplements or nutraceuticals for immuno-modulatory functions. Dendritic cells (DCs), the most potent antigen presenting cells, play an important role in both innate and adaptive immunities. In this study, we investigated the specific and differential gene expression in human immature DCs (iDCs) in response to treatment with a butanol fraction containing defined bioactive phytocompounds extracted from stems and leaves of <it>Echinacea purpurea</it>, that we denoted [BF/S+L/Ep].</p> <p>Results</p> <p>Affymetrix DNA microarray results showed significant up regulation of specific genes for cytokines (IL-8, IL-1β, and IL-18) and chemokines (CXCL 2, CCL 5, and CCL 2) within 4 h after [BF/S+L/Ep] treatment of iDCs. Bioinformatics analysis of genes expressed in [BF/S+L/Ep]-treated DCs revealed a key-signaling network involving a number of immune-modulatory molecules leading to the activation of a downstream molecule, adenylate cyclase 8. Proteomic analysis showed increased expression of antioxidant and cytoskeletal proteins after treatment with [BF/S+L/Ep] and cichoric acid.</p> <p>Conclusion</p> <p>This study provides information on candidate target molecules and molecular signaling mechanisms for future systematic research into the immune-modulatory activities of an important traditional medicinal herb and its derived phytocompounds.</p

Proteomic profiling reveals α1-antitrypsin, α1-microglobulin, and clusterin as preeclampsia-related serum proteins in pregnant women

AbstractObjectivePreeclampsia is a major cause of mortality in pregnant women but the underlying mechanism remains unclear to date. In this study, we attempted to identify candidate proteins that might be associated with preeclampsia in pregnant women by means of proteomics tools.Materials and methodsDifferentially expressed proteins in serum samples obtained from pregnant women with severe preeclampsia (n = 8) and control participants (n = 8) were identified using two-dimensional gel electrophoresis (2-DE) followed by peptide mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Additional serum samples from 50 normal and 41 pregnant women with severe preeclampsia were analyzed by immunoassay for validation.ResultsTen protein spots were found to be upregulated significantly in women with severe preeclampsia. These protein spots had the peptide mass fingerprints matched to α1-antitrypsin, α1-microglobulin, clusterin, and haptoglobin. Immunoassays in an independent series of serum samples showed that serum α1-antitrypsin, α1-microglobulin, and clusterin levels of severe preeclampsia patients (n = 41) were significantly higher than those in the normal participants (n = 50; α1-antitrypsin 295.95 ± 50.94 mg/dL vs. 259.31 ± 33.90 mg/dL, p = 0.02; α1-microglobulin 0.029 ± 0.004 mg/mL vs. 0.020 ± 0.004 mg/mL, p < 0.0001; clusterin 77.6 ± 16.15 μg/dL vs. 67.6 ± 15.87 μg/dL, p < 0.05).ConclusionIdentification of these proteins by proteomics analysis enables further understanding of the pathophysiology of preeclampsia. Further studies are warranted to investigate the role of these biomarkers in prediction of this disease

Pretreatment with a Heat-Killed Probiotic Modulates the NLRP3 Inflammasome and Attenuates Colitis-Associated Colorectal Cancer in Mice.

Colorectal cancer (CRC) is one of the most common malignancies worldwide. Inflammation contributes to cancer development and inflammatory bowel disease is an important risk factor for CRC. The aim of this study is to assess whether a widely used probiotic Enterococcus faecalis can modulate the NLRP3 inflammasome and protect against colitis and colitis-associated CRC. We studied the effect of heat-killed cells of E. faecalis on NLRP3 inflammasome activation in THP-1-derived macrophages. Pretreatment of E. faecalis or NLRP3 siRNA can inhibit NLRP3 inflammasome activation in macrophages in response to fecal content or commensal microbes, P. mirabilis or E. coli, according to the reduction of caspase-1 activation and IL-1β maturation. Mechanistically, E. faecalis attenuates the phagocytosis that is required for the full activation of the NLRP3 inflammasome. In in vivo mouse experiments, E. faecalis can ameliorate the severity of intestinal inflammation and thereby protect mice from dextran sodium sulfate (DSS)-induced colitis and the formation of CRC in wild type mice. On the other hand, E. faecalis cannot prevent DSS-induced colitis in NLRP3 knockout mice. Our findings indicate that application of the inactivated probiotic, E. faecalis, may be a useful and safe strategy for attenuation of NLRP3-mediated colitis and inflammation-associated colon carcinogenesis

The Taiwan Birth Panel Study: a prospective cohort study for environmentally- related child health

<p>Abstract</p> <p>Background</p> <p>The Taiwan Birth Panel Study (TBPS) is a prospective follow-up study to investigate the development of child health and disease in relation to in-utero and/or early childhood environmental exposures. The rationale behind the establishment of such a cohort includes the magnitude of potential environmental exposures, the timing of exposure window, fatal and children's susceptibility to toxicants, early exposure delayed effects, and low-level or unknown neurodevelopmental toxicants.</p> <p>Methods</p> <p>A total of 486 mother-infant paired was enrolled from April 2004 to January 2005 in this study. Maternal blood before delivery, placenta and umbilical cord blood at birth, and mothers' urine after delivery were collected. The follow-up was scheduled at birth, 4, 6 months, and 1, 2, 3 and 5 years. The children's blood, urine, hair, and saliva were collected at 2 years of age and children's urine was collected at 5 years of age as well. The study has been approved by the ethical committee of National Taiwan University Hospital. All the subjects signed the inform consent on entering the study and each of the follow up.</p> <p>Results</p> <p>Through this prospective birth cohort, the main health outcomes were focused on child growth, neurodevelopment, behaviour problem and atopic diseases. We investigated the main prenatal and postnatal factors including smoking, heavy metals, perfluorinated chemicals, and non-persistent pesticides under the consideration of interaction of the environment and genes.</p> <p>Conclusions</p> <p>This cohort study bridges knowledge gaps and answers unsolved issues in the low-level, prenatal or postnatal, and multiple exposures, genetic effect modification, and the initiation and progression of "environmentally-related childhood diseases."</p