Explore the vast range of titles available.

Microscopy has greatly advanced our understanding of biology. Although significant progress has recently been made in optical microscopy to break the diffraction-limit barrier, reliance of such techniques on fluorescent labeling technologies prohibits quantitative 3D imaging of the entire contents of cells. Cryoelectron microscopy can image pleomorphic structures at a resolution of 3—5 nm, but is only applicable to thin or sectioned speciments. Here, we report quantitative 3D imaging of a whole, unstained cell at a resolution of 50—60 nm by X-ray diffraction microscopy. We identified the 3D morphology and structure of cellular organelles including cell wall, vacuole, endoplasmic reticulum, mitochondria, granules, nucleus, and nucleolus inside a yeast spore cell. Furthermore, we observed a 3D structure protruding from the reconstructed yeast spore, suggesting the spore germination process. Using cryogenic technologies, a 3D resolution of 5—10 nm should be achievable by X-ray diffraction microscopy. This work hence paves a way for quantitative 3D imaging of a wide range of biological specimens at nanometer-scale resolutions that are too thick for electron microscopy.

Rheb is a unique member of the Ras superfamily GTP-binding proteins. We as well as others previously have shown that Rheb is a critical component of the TSC/TOR signaling pathway. In fission yeast, Rheb is encoded by the rhb1 gene. Rhb1p is essential for growth and directly interacts with Tor2p. In this article, we report identification of 22 single amino acid changes in the Tor2 protein that enable growth in the absence of Rhb1p. These mutants also exhibit decreased mating efficiency. Interestingly, the mutations are located in the C-terminal half of the Tor2 protein, clustering mainly within the FAT and kinase domains. We noted some differences in the effect of a mutation in the FAT domain (L1310P) and in the kinase domain (E2221K) on growth and mating. Although the Tor2p mutations bypass Rhb1p's requirement for growth, they are incapable of suppressing Rhb1p's requirement for resistance to stress and toxic amino acids, pointing to multiple functions of Rhb1p. In mammalian systems, we find that mammalian target of rapamycin (mTOR) carrying analogous mutations (L1460P or E2419K), although sensitive to rapamycin, exhibits constitutive activation even when the cells are starved for nutrients. These mutations do not show significant difference in their ability to form complexes with Raptor, Rictor, or mLST8. Furthermore, we present evidence that mutant mTOR can complex with wild-type mTOR and that this heterodimer is active in nutrient-starved cells.

Early in development, a part of the embryo is set aside to become the germ cell lineage that will ultimately differentiate to form sperm and eggs and transmit genetic information to the next generation. Men with deletions encompassing the Y-chromosome DAZ genes have few or no germ cells but are otherwise healthy, indicating they harbor specific defects in formation or maintenance of germ cells. A DAZ homolog, DAZL (DAZ-Like), is found in diverse organisms, including humans and is required for germ cell development in males and/or females. We identified proteins that interact with DAZ proteins to better understand their function in human germ cells. Here, we show that PUM2, a human homolog of Pumilio, a protein required to maintain germ line stem cells in Drosophila and Caenorhabditis elegans, forms a stable complex with DAZ through the same functional domain required for RNA binding, protein-protein interactions and rescue of Pumilio mutations in flies. We also show that PUM2 is expressed predominantly in human embryonic stem cells and germ cells and colocalizes with DAZ and DAZL in germ cells. These data implicate PUM2 as a component of conserved cellular machinery that may be required for germ cell development.

Farnesyltransferase inhibitors (FTIs) represent a new class of anticancer drugs that show promise in blocking the growth of tumors. Here, we report that FTIs are capable of inducing apoptosis of transformed but not untransformed cells. Treatment of v-K-ras-transformed normal rat kidney (KNRK) cells with FTIs leads to the induction of apoptotic cell morphology, chromatin condensation and DNA fragmentation. In addition, fluorescence-activated cell sorter analysis of FTI-treated KNRK cells shows a sub-G1apoptotic peak (chromosome content of <2 N). This FTI-induced apoptosis is evident only when the cells are grown in low serum conditions (0.1% fetal calf serum) and is observed selectively with transformed KNRK cells and not with untransformed NRK cells. Further analysis of the mechanism underlying this apoptosis has shown that FTI treatment of KNRK cells results in the activation of caspase 3 but not caspase 1. Moreover, the addition of Z-DEVD-fmk, an agent that interferes with caspase 3 activity, can inhibit FTI-induced apoptosis in a dose-dependent manner. Introduction of the CASP-3 gene into MCF7 cells, which lack caspase 3 activity, results in a significant increase of FTI-induced apoptosis. Furthermore, FTI induces the release of cytochrome c into the cytosol. This release is an important feature of caspase 3-mediated apoptosis. These results suggest that FTIs induce apoptosis through the release of cytochrome c from the mitochondria resulting in caspase 3 activation.

The timing of vaccine availability is essential for an effective response to pandemic influenza. In 2009, vaccine became available after the disease peak, and this has motivated the development of next generation vaccine technologies for more rapid responses. The SAM(®) vaccine platform, now in pre-clinical development, is based on a synthetic, self-amplifying mRNA, delivered by a synthetic lipid nanoparticle (LNP). When used to express seasonal influenza hemagglutinin (HA), a SAM vaccine elicited potent immune responses, comparable to those elicited by a licensed influenza subunit vaccine preparation. When the sequences coding for the HA and neuraminidase (NA) genes from the H7N9 influenza outbreak in China were posted on a web-based data sharing system, the combination of rapid and accurate cell-free gene synthesis and SAM vaccine technology allowed the generation of a vaccine candidate in 8 days. Two weeks after the first immunization, mice had measurable hemagglutinin inhibition (HI) and neutralizing antibody titers against the new virus. Two weeks after the second immunization, all mice had HI titers considered protective. If the SAM vaccine platform proves safe, potent, well tolerated and effective in humans, fully synthetic vaccine technologies could provide unparalleled speed of response to stem the initial wave of influenza outbreaks, allowing first availability of a vaccine candidate days after the discovery of a new virus.

The timing of vaccine availability is essential for an effective response to pandemicinfluenza. In 2009, vaccine became available after the disease peak, and this hasmotivated the development of next generation vaccine technologies for more rapidresponses. The SAM® vaccine platform, now in pre-clinical development, isbased on a synthetic, self-amplifying mRNA, delivered by a synthetic lipid nanoparticle(LNP). When used to express seasonal influenza hemagglutinin (HA), a SAM vaccine elicitedpotent immune responses, comparable to those elicited by a licensed influenza subunitvaccine preparation. When the sequences coding for the HA and neuraminidase (NA) genesfrom the H7N9 influenza outbreak in China were posted on a web-based data sharing system,the combination of rapid and accurate cell-free gene synthesis and SAM vaccine technologyallowed the generation of a vaccine candidate in 8 days. Two weeks after the firstimmunization, mice had measurable hemagglutinin inhibition (HI) and neutralizing antibodytiters against the new virus. Two weeks after the second immunization, all mice had HItiters considered protective. If the SAM vaccine platform proves safe, potent, welltolerated and effective in humans, fully synthetic vaccine technologies could provideunparalleled speed of response to stem the initial wave of influenza outbreaks, allowingfirst availability of a vaccine candidate days after the discovery of a new virus.

Ras superfamily G-proteins are involved in a variety of physiological roles. Recently, a number of new members of this family of small G-proteins have been identified, and studies of these proteins are likely to expand our knowledge on the mechanisms and functions that small G-proteins play in the cell. Of these newly identified proteins, we focused our study on the mammalian Rheb protein, whose function remains undefined. We found that Rheb homologues exist in a variety of organisms including yeast, fruitfly, zebrafish and sea squirt. Analysis of these homologues showed (1) 100% conservation of an arginine at the third position of the G1-box, (2) high conservation of effector domain sequences, and (3) presence of a C-terminal farnesylation signal. Using yeast as a model genetic system, we investigated the function of the yeast Rheb homologue, ScRheb. Disruption and phenotypic analysis showed that the loss of ScRheb resulted in hypersensitivity to canavanine and thialysine, which are analogues of arginine and lysine, respectively. Further investigation showed that loss of ScRheb resulted in an increased uptake specifically of the amino acids arginine and lysine, suggesting that the hypersensitivity is due to a loss of proper regulation of arginine and lysine uptake. We further show evidence to suggest that this regulation is likely at the level of transport through the permeases for these amino acids. Using mutational analysis we further examined the importance of the various regions of ScRheb for its function. We found that mutations in the effector domain as well as a mutation that is expected to decrease GTP affinity affect the ability of ScRheb to complement hypersensitivity to canavanine and thialysine. Furthermore, ScRheb that carries a mutation that destroys the farnesylation signal is unable to suppress the increased arginine uptake. We also found that ScRheb is farnesylated in vitro and in vivo . This result indicates that farnesylation is important for function of ScRheb. The role of farnesylation in arginine uptake was also examined. We find that yeast cells deficient in farnesylation also shows a defective control of arginine uptake. This defect can be partially suppressed by ScRheb carrying a geranylgernylation signal, which circumvents the requirement for farnesylation. These results demonstrate that ScRheb, and possibly the other Rheb proteins, are involved in regulating arginine uptake in a farnesylation dependent manner.

Secondary lymphedema often develops after cancer surgery, and over 250 million patients suffer from this complication. A major symptom of secondary lymphedema is swelling with fibrosis, which lowers the patient's quality of life, even if cancer does not recur. Nonetheless, the pathophysiology of secondary lymphedema remains unclear, with therapeutic approaches limited to physical or surgical therapy. There is no effective pharmacological therapy for secondary lymphedema. Notably, the lack of animal models that accurately mimic human secondary lymphedema has hindered pathophysiological investigations of the disease. Here, we developed a novel rat hindlimb model of secondary lymphedema and showed that our rat model mimics human secondary lymphedema from early to late stages in terms of cell proliferation, lymphatic fluid accumulation, and skin fibrosis. Using our animal model, we investigated the disease progression and found that transforming growth factor‐beta 1 (TGFB1) was produced by macrophages in the acute phase and by fibroblasts in the chronic phase of the disease. TGFB1 promoted the transition of fibroblasts into myofibroblasts and accelerated collagen synthesis, resulting in fibrosis, which further indicates that myofibroblasts and TGFB1/Smad signaling play key roles in fibrotic diseases. Furthermore, the presence of myofibroblasts in skin samples from lymphedema patients after cancer surgery emphasizes the role of these cells in promoting fibrosis. Suppression of myofibroblast‐dependent TGFB1 production may therefore represent an effective pharmacological treatment for inhibiting skin fibrosis in human secondary lymphedema after cancer surgery. Secondary lymphedema develops and causes skin fibrosis after cancer surgery. We developed a novel rat hindlimb model that accurately mimics human secondary lymphedema, and investigated disease progression. We found that myofibroblasts and transforming growth factor‐beta 1/Smad signaling play key roles in the skin fibrosis of secondary lymphedema.

Neutrophil extracellular traps (NETs) are associated with the extracellular release of nuclear chromatin decorated with cytoplasmic proteins. Excessive release of NETs has been reported in chronic lung diseases, including chronic obstructive pulmonary disease (COPD). However, the role of NETs in the pathogenesis of COPD remains unclear. Peptidylarginine deaminase 4 (PAD4) contributes to NET formation. Therefore, in an elastase (ELS)-induced emphysema mouse model, we examined the role of PAD4 using Padi4 gene knockout (KO) mice. First, we confirmed that ELS induced NET formation in the parenchyma of the lungs. PAD4 deficiency suppressed ELS-induced NET expression and tended to ameliorate the lung tissue injury. The cellular profile of bronchoalveolar lavage fluid (BALF) did not differ between the two groups. Additionally, PAD4 deficiency ameliorated emphysema and apoptosis in lung cells. Finally, we examined the effects of PAD4 on comprehensive gene expression signatures using RNA sequencing. Enrichment analysis of the transcriptomic data revealed that the expression of several genes associated with COPD pathogenesis was altered in the KO mice. Overall, the results suggest that PAD4 deficiency improves NET formation and emphysema in the lungs; this pathway can be a potential therapeutic target for the treatment of COPD.

Fluorescence-guided diagnostics is one of the most promising approaches for facile detection of cancer in situ . Here we focus on β-galactosidase, which is overexpressed in primary ovarian cancers, as a molecular target for visualizing peritoneal metastases from ovarian cancers. As existing fluorescence probes are unsuitable, we have designed membrane-permeable HMRef-βGal, in which the optimized intramolecular spirocyclic function affords >1,400-fold fluorescence enhancement on activation. We confirm that HMRef-βGal sensitively detects intracellular β-galactosidase activity in several ovarian cancer lines. In vivo , this probe visualizes metastases as small as <1 mm in diameter in seven mouse models of disseminated human peritoneal ovarian cancer (SHIN3, SKOV3, OVK18, OVCAR3, OVCAR4, OVCAR5 and OVCAR8). Because of its high brightness, real-time detection of metastases with the naked eye is possible. Endoscopic fluorescence detection of metastases is also demonstrated. The results clearly indicate preclinical potential value of the probe for fluorescence-guided diagnosis of peritoneal metastases from ovarian cancers. Surgical removal of the metastases remains a life-extending approach to ovarian cancer, but the nodules are difficult to detect. Here the authors show that a new cell-permeable probe for β-galactosidase can sensitively and specifically detect peritoneal metastases in mouse models of ovarian cancer.