BackgroundThe transcription factor B-Myb is present in all proliferating cells, and in mice engineered to remove this gene, embryos die in utero just after implantation due to inner cell mass defects. This lethal phenotype has generally been attributed to a proliferation defect in the cell cycle phase of G1.Methodology/Principal FindingsIn the present study, we show that the major cell cycle defect in murine embryonic stem (mES) cells occurs in G2/M. Specifically, knockdown of B-Myb by short-hairpin RNAs results in delayed transit through G2/M, severe mitotic spindle and centrosome defects, and in polyploidy. Moreover, many euploid mES cells that are transiently deficient in B-Myb become aneuploid and can no longer be considered viable. Knockdown of B-Myb in mES cells also decreases Oct4 RNA and protein abundance, while over-expression of B-MYB modestly up-regulates pou5f1 gene expression. The coordinated changes in B-Myb and Oct4 expression are due, at least partly, to the ability of B-Myb to directly modulate pou5f1 gene promoter activity in vitro. Ultimately, the loss of B-Myb and associated loss of Oct4 lead to an increase in early markers of differentiation prior to the activation of caspase-mediated programmed cell death.Conclusions/SignificanceAppropriate B-Myb expression is critical to the maintenance of chromosomally stable and pluripotent ES cells, but its absence promotes chromosomal instability that results in either aneuploidy or differentiation-associated cell death.

Human immunodeficiency virus type 1 (HIV-1) infection occurs in the central nervous system and causes a variety of neurobehavioral and neuropathological disorders. Both microglia, the residential macrophages in the brain, and astrocytes are susceptible to HIV-1 infection. Unlike microglia that express and utilize CD4 and chemokine coreceptors CCR5 and CCR3 for HIV-1 infection, astrocytes fail to express CD4. Astrocytes express several chemokine coreceptors; however, the involvement of these receptors in astrocyte HIV-1 infection appears to be insignificant. In the present study using an expression cloning strategy, the cDNA for the human mannose receptor (hMR) was found to be essential for CD4-independent HIV-1 infectivity. Ectopic expression of functional hMR rendered U87.MG astrocytic cells susceptible to HIV-1 infection, whereas anti-hMR serum and hMR-specific siRNA blocked HIV-1 infection in human primary astrocytes. In agreement with these findings, hMR bound to HIV-1 virions via the abundant and highly mannosylated sugar moieties of HIV-1 envelope glycoprotein gp120 in a Ca 2؉ -dependent fashion. Moreover, hMR-mediated HIV-1 infection was dependent upon endocytic trafficking as assessed by transmission electron microscopy, as well as inhibition of viral entry by endosomo-and lysosomotropic drugs. Taken together, these results demonstrate the direct involvement of hMR in HIV-1 infection of astrocytes and suggest that HIV-1 interaction with hMR plays an important role in HIV-1 neuropathogenesis.Astrocytes, often identified by glial fibrillary acidic protein expression, constitute a majority of the cells in the brain and are essential for maintaining homeostasis in the brain and, hence, normal brain activities. A number of different and quite diverse functions have been attributed to astrocytes. These include secretion of neurotrophic factors, regulation of the interstitial pH, uptake and metabolism of neurotransmitters, antioxidant defense via scavenging and transforming oxygen free radicals into nontoxic species, modulation of neuronal signals, being an essential structural component of the bloodbrain barrier, and participating in immune responses through production and secretion of cytokines, proteases, protease inhibitors, adhesion molecules, and extracellular matrix components that are key mediators of immunity and inflammation (for recent reviews, see references 6, 13, and 58). Although it is important to note that several of the functions listed above are still controversial, the highly dynamic and reciprocal relationship between astrocytes and neurons suggests that dysfunction of astrocytes could contribute to the pathogenesis of neurological diseases.

The morphology of nanoparticles influences their cellular uptake process, while rough surface-enhanced affinity renders rough nanoparticles desirable in related biomedical applications. In this work, rattle-structured rough nanocapsules (Au@HSN-PGEA, AHPs) composed of in-situ-formed gold nanorod (Au NR) cores and polycationic mesoporous silica shells were constructed for trimodal complementary cancer therapy. Taking advantage of surface roughness, near-infrared (NIR) responsiveness, and controlled release manner, AHPs were expected to realize the co-delivery of sorafenib (SF, a hydrophobic antiproliferative and antiangiogenic drug) and antioncogene p53 for malignant hepatocellular carcinoma treatment. The rough surface feature of AHP was investigated for cellular uptake and the subsequent gene transfection. The feasibility of photothermal Au NR cores for NIR-triggered SF release was also tested. Notably, synergistic effects based on photothemal therapy-enhanced chemotherapy were achieved. In addition, the good in vivo performance of the proposed multifunctional nanoparticles with rough surfaces was also demonstrated. The current work extends the biomedical applications of the intriguing rough nanoparticles and provides a facile strategy to construct flexible platforms for complementary gene/chemo/photothermal therapy.

Protein kinase A-anchoring proteins (AKAPs) play important roles in the compartmentation of cAMP signaling, anchoring protein kinase A (PKA) to specific cellular organelles and serving as scaffolds that assemble localized signaling cascades. Although AKAPs have been recently shown to bind adenylyl cyclase (AC), the functional significance of this association has not been studied. In cardiac myocytes, the muscle protein kinase A-anchoring protein ␤ (mAKAP␤) coordinates cAMP-dependent, calcium, and MAP kinase pathways and is important for cellular hypertrophy. We now show that mAKAP␤ selectively binds type 5 AC in the heart and that mAKAP␤-associated AC activity is absent in AC5 knock-out hearts. Consistent with its known inhibition by PKA phosphorylation, AC5 is inhibited by association with mAKAP␤-PKA complexes. AC5 binds to a unique N-terminal site on mAKAP-(245-340), and expression of this peptide disrupts endogenous mAKAP␤-AC association. Accordingly, disruption of mAKAP␤-AC5 complexes in neonatal cardiac myocytes results in increased cAMP and hypertrophy in the absence of agonist stimulation. Taken together, these results show that the association of AC5 with the mAKAP␤ complex is required for the regulation of cAMP second messenger controlling cardiac myocyte hypertrophy.The formation of multimolecular protein complexes contributes to the specificity of intracellular signaling pathways, including those regulating cardiac myocyte hypertrophy. The cAMP-dependent protein kinase (PKA) 3 is targeted to specific intracellular domains by protein kinase A-anchoring proteins (AKAPs) that often serve as scaffolding proteins for diverse signaling enzymes (1). In the heart, global disruption of PKA anchoring affects cardiac contractility, while the inhibited expression of individual AKAPs such as mAKAP␤ or AKAPLbc attenuates adrenergic-induced hypertrophy of cultured neonatal myocytes (2-4). We have recently shown that specific AKAPs, namely AKAP79 and Yotiao, bind adenylyl cyclases (AC) (5, 6). However, the functional significance of AC-AKAP complexes has not been demonstrated. mAKAP␤, expressed in striated myocytes, is one of two known splice variants encoded by the single mAKAP (AKAP6) gene (7). We previously published that mAKAP␤ is primarily localized to the outer membrane of the nuclear envelope via direct binding to nesprin-1␣ (4, 8). In cardiac myocytes, mAKAP␤ serves as the scaffold for a multimolecular signaling complex that in addition to PKA includes the ryanodine receptor (RyR2), the protein phosphatases PP2A and calcineurin, phosphodiesterase 4D3 (PDE4D3), exchange protein activated by cAMP (Epac1), ERK5, and MEK5 mitogen-activated protein kinases, molecules implicated in the regulation of cardiac hypertrophy (4, 7-13). mAKAP␤ complexes facilitate crosstalk between MAP kinase, calcium, and cAMP signaling pathways, permitting feedback inhibition of cAMP levels and the dynamic regulation of PKA and ERK5 activity (4, 9 -13). Accordingly, mAKAP␤ RNAi attenuates adrenergic and cytokine-induced hypertrophy of...

Currently sodium-ion batteries (SIBs) as energy storage technology have attracted lots of interest due to their safe, cost-effective, and nonpoisonous advantages. However, many challenges remain for development of SIBs with high specific capacity, high rate capability, and long cycle life. Therefore, CuS as an important earth-abundant, low-cost semiconductor was applied as anode of SIBs with ether-based electrolyte instead of conventional ester-based electrolyte. By incorporating reduced graphene oxide (RGO) into CuS nanosheets and optimizing the cutoff voltage, it is found that the sodium-ion storage performance can be greatly enhanced using ether-based electrolyte. The CuS-RGO composites deliver an initial Coulombic efficiency of 94% and a maximum specific capacity of 392.9 mAh g after 50 cycles at a current density of 100 mA g. And a specific capacity of 345 mAh g is kept after 450 cycles at a current density of 1 A g. Such an excellent electrochemical performance is ascribed to the conductive network construction of CuS-RGO composites, the suppression of dissolved polysulfide intermediates by using ether-based electrolyte, and the avoidance of conversion-type reaction by optimizing the cutoff voltage.

The complete sequence of the mitochondrial genome of Tetrahymena thermophila has been determined and compared with the mitochondrial genome of Tetrahymena pyriformis. The sequence similarity clearly indicates homology of the entire T.thermophila and T.pyriformis mitochondrial genomes. The T.thermophila genome is very compact, most of the intergenic regions are short (only three are longer than 63 bp) and comprise only 3.8% of the genome. The nad9 gene is tandemly duplicated in T.thermophila. Long terminal inverted repeats and the nad9 genes are undergoing concerted evolution. There are 55 putative genes: three ribosomal RNA genes, eight transfer RNA genes, 22 proteins with putatively assigned functions and 22 additional open reading frames of unknown function. In order to extend indications of homology beyond amino acid sequence similarity we have examined a number of physico-chemical properties of the mitochondrial proteins, including theoretical pI, molecular weight and particularly the predicted transmembrane spanning regions. This approach has allowed us to identify homologs to ymf58 (nad4L), ymf62 (nad6) and ymf60 (rpl6).

There is substantial evidence on the influence of political outcomes on the business cycle and stock market. We further hypothesize that uncertainty about the outcome of a U.S. presidential election should be reflected in pre-election common stock returns. Prior research pools returns based on the party of the winning candidate, assuming that the outcome of the election is known a priori. We use candidate preference (i.e., polling) data to construct a measure of election uncertainty. We find that if the election does not have a candidate with a dominant lead, stock market volatility (risk) and average returns rise. 2006 The Southern Finance Association and the Southwestern Finance Association.

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