Nếu Đông Phi không kiểm soát được, hàng tỷ con châu chấu sẽ tiếp tục sinh sôi nảy nở và có thể lớn gấp 400 lần dịch cũ

Among the unaccounted for items were seven boxes of masks, 50 tubs of sanitizing wipes, 10 containers of soap and 20 bottles of hand sanitizer.

A statistical analysis of Indianapolis' homicides shows that young black males are four times more likely than others to be victims of homicide.

Indianapolis native Doug Jones takes his creature craft to new heights in Guillermo del Toro's "The Shape of Water."

When the Chargers legend isn't carrying a team on his back, Rivers has been far more efficient.

How important are counting stats for quarterbacks? How important is winning in the postseason? Those are the questions about Rivers.

Jack Doyle can't get on the field with his new teammates but that hasn't stopped him from forging relationships.

Rivers has been named the coach in waiting at St. Michael Catholic High School in Fairhope, according to an AL.com report.

The last business standing on a flood-prone piece of land is expected to vacate this year, making way for a 15-acre park with an amphitheater.

A 15-acre park with amphitheater, playground and farmer's market plaza is planned for the southwest side of Franklin.

Jam-band roots, revamped lineup and a new album translate into a fresh performance by the Dave Matthews Band at the venue once known as Deer Creek.

Modern rock giants Weezer and Pixies deliver power-meets-melody masterpieces in Indiana.

James Maddison is unstoppable against former team-mate Callum Wilson while Jofra Archer suffers a last-gasp defeat on day three of the Premier League Fifa invitational.

How important are counting stats for quarterbacks? How important is winning in the postseason? Those are the questions about Rivers.

Jack Doyle can't get on the field with his new teammates but that hasn't stopped him from forging relationships.

Rivers has been named the coach in waiting at St. Michael Catholic High School in Fairhope, according to an AL.com report.

A chronology of key events

Key facts, figures and dates

The Dutch politician and MEP Sophie in ’t Veld on the economic impact on the EU of coronavirus.

Eisner-winning cartoonist Brian Fies faces down another fire two years after losing his Northern California home. "I'm mostly numb," he says.

The true star of “Resident Evil 3” is its supurb graphics engine.

Getting a jump on early lines can give bettors added value in their wagering. Here are three teams to focus on for Week 4.

New England has a negative point differential heading into Week 4 for the first time since 2008.

Philadelphia

Hear about travel to Memphis, Tennessee as the Amateur Traveler talks to Lance from tripsbylance.com about this city where he has lived on and off for 20+ years. Lance tells us that there is more to Memphis than Elvis and Graceland.

Hear about travel to the region around Island of Cebu as the Amateur Traveler talks to Tommo & Megsy from fivedollartraveller.com about their vacation in Visayas, the central group of islands in the Philippines. They visited the islands of Bohol, Cebu and Negros. 

Hear about travel to Philadelphia, Pennsylvania as the Amateur Traveler talks to Larissa and Michael Milne of changesinlongitude.com. They recently authored the "Philadelphia Liberty Trail" book.

Hear about travel to the Philippines as the Amateur Traveler talks to Julie Longland about her travel to the Cordilleras mountain region and the island of Palawan which was just named the "Best Island in the World".

Philadelphia Phillies star Bryce Harper believes Major League Baseball should relax its "dumb" rule preventing top players from competing in the Olympics.

Phishing is incredibly common, yet most people feel it has gotten harder to spot in recent years. Cyber criminals rely on their knowledge of human psychology to make you do things you wouldn’t normally do. They also know that if they scare you enough they can manipulate you into doing what they want you to […]

The post Preventing Phishing With Education appeared first on Dumb Little Man.

Previous studies have shown that sphingosine kinase interacting protein (SKIP) inhibits sphingosine kinase (SK) function in fibroblasts. SK phosphorylates sphingosine producing the potent signaling molecule sphingosine-1-phosphate (S1P). SKIP gene (SPHKAP) expression is silenced by hypermethylation of its promoter in acute myeloid leukemia (AML). However, why SKIP activity is silenced in primary AML cells is unclear. Here, we investigated the consequences of SKIP down-regulation in AML primary cells and the effects of SKIP re-expression in leukemic cell lines. Using targeted ultra-HPLC-tandem MS (UPLC-MS/MS), we measured sphingolipids (including S1P and ceramides) in AML and control cells. Primary AML cells had significantly lower SK activity and intracellular S1P concentrations than control cells, and SKIP-transfected leukemia cell lines exhibited increased SK activity. These findings show that SKIP re-expression enhances SK activity in leukemia cells. Furthermore, other bioactive sphingolipids such as ceramide were also down-regulated in primary AML cells. Of note, SKIP re-expression in leukemia cells increased ceramide levels 2-fold, inactivated the key signaling protein extracellular signal-regulated kinase, and increased apoptosis following serum deprivation or chemotherapy. These results indicate that SKIP down-regulation in AML reduces SK activity and ceramide levels, an effect that ultimately inhibits apoptosis in leukemia cells. The findings of our study contrast with previous results indicating that SKIP inhibits SK function in fibroblasts and therefore challenge the notion that SKIP always inhibits SK activity.

The peroxisome is a subcellular organelle that functions in essential metabolic pathways, including biosynthesis of plasmalogens, fatty acid β-oxidation of very-long-chain fatty acids, and degradation of hydrogen peroxide. Peroxisome biogenesis disorders (PBDs) manifest as severe dysfunction in multiple organs, including the central nervous system (CNS), but the pathogenic mechanisms in PBDs are largely unknown. Because CNS integrity is coordinately established and maintained by neural cell interactions, we here investigated whether cell-cell communication is impaired and responsible for the neurological defects associated with PBDs. Results from a noncontact co-culture system consisting of primary hippocampal neurons with glial cells revealed that a peroxisome-deficient astrocytic cell line secretes increased levels of brain-derived neurotrophic factor (BDNF), resulting in axonal branching of the neurons. Of note, the BDNF expression in astrocytes was not affected by defects in plasmalogen biosynthesis and peroxisomal fatty acid β-oxidation in the astrocytes. Instead, we found that cytosolic reductive states caused by a mislocalized catalase in the peroxisome-deficient cells induce the elevation in BDNF secretion. Our results suggest that peroxisome deficiency dysregulates neuronal axogenesis by causing a cytosolic reductive state in astrocytes. We conclude that astrocytic peroxisomes regulate BDNF expression and thereby support neuronal integrity and function.

Heterotrimeric G proteins mediate a variety of signaling processes by coupling G protein–coupled receptors to intracellular effector molecules. In Drosophila, the Gαq gene encodes several Gαq splice variants, with the Gαq1 isoform protein playing a major role in fly phototransduction. However, Gαq1 null mutant flies still exhibit a residual light response, indicating that other Gαq splice variants or additional Gq α subunits are involved in phototransduction. Here, we isolated a mutant fly with no detectable light responses, decreased rhodopsin (Rh) levels, and rapid retinal degeneration. Using electrophysiological and genetic studies, biochemical assays, immunoblotting, real-time RT-PCR, and EM analysis, we found that mutations in the Gαq gene disrupt light responses and demonstrate that the Gαq3 isoform protein is responsible for the residual light response in Gαq1 null mutants. Moreover, we report that Gαq3 mediates rhodopsin synthesis. Depletion of all Gαq splice variants led to rapid light-dependent retinal degeneration, due to the formation stable Rh1-arrestin 2 (Arr2) complexes. Our findings clarify essential roles of several different Gαq splice variants in phototransduction and retinal integrity in Drosophila and reveal that Gαq3 functions in rhodopsin synthesis.

Hippo pathway signaling limits cell growth and proliferation and maintains the stem-cell niche. These cellular events result from the coordinated activity of a core kinase cassette that is regulated, in part, by interactions involving Hippo, Salvador, and dRassF. These interactions are mediated by a conserved coiled-coil domain, termed SARAH, in each of these proteins. SARAH domain–mediated homodimerization of Hippo kinase leads to autophosphorylation and activation. Paradoxically, SARAH domain–mediated heterodimerization between Hippo and Salvador enhances Hippo kinase activity in cells, whereas complex formation with dRassF inhibits it. To better understand the mechanism by which each complex distinctly modulates Hippo kinase and pathway activity, here we biophysically characterized the entire suite of SARAH domain–mediated complexes. We purified the three SARAH domains from Drosophila melanogaster and performed an unbiased pulldown assay to identify all possible interactions, revealing that isolated SARAH domains are sufficient to recapitulate the cellular assemblies and that Hippo is a universal binding partner. Additionally, we found that the Salvador SARAH domain homodimerizes and demonstrate that this interaction is conserved in Salvador's mammalian homolog. Using native MS, we show that each of these complexes is dimeric in solution. We also measured the stability of each SARAH domain complex, finding that despite similarities at both the sequence and structural levels, SARAH domain complexes differ in stability. The identity, stoichiometry, and stability of these interactions characterized here comprehensively reveal the nature of SARAH domain–mediated complex formation and provide mechanistic insights into how SARAH domain–mediated interactions influence Hippo pathway activity.

Glial cell line–derived neurotrophic factor (GDNF) is a growth factor that regulates the health and function of neurons and other cells. GDNF binds to GDNF family receptor α1 (GFRa1), and the resulting complex activates the RET receptor tyrosine kinase and subsequent downstream signals. This feature restricts GDNF activity to systems in which GFRa1 and RET are both present, a scenario that may constrain GDNF breadth of action. Furthermore, this co-dependence precludes the use of GDNF as a tool to study a putative functional cross-talk between GFRa1 and RET. Here, using biochemical techniques, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and immunohistochemistry in murine cells, tissues, or retinal organotypic cultures, we report that a naphthoquinone/quinolinedione family of small molecules (Q compounds) acts as RET agonists. We found that, like GDNF, signaling through the parental compound Q121 is GFRa1-dependent. Structural modifications of Q121 generated analogs that activated RET irrespective of GFRa1 expression. We used these analogs to examine RET–GFRa1 interactions and show that GFRa1 can influence RET-mediated signaling and enhance or diminish AKT Ser/Thr kinase or extracellular signal-regulated kinase signaling in a biased manner. In a genetic mutant model of retinitis pigmentosa, a lead compound, Q525, afforded sustained RET activation and prevented photoreceptor neuron loss in the retina. This work uncovers key components of the dynamic relationships between RET and its GFRa co-receptor and provides RET agonist scaffolds for drug development.

Formate oxidation to carbon dioxide is a key reaction in one-carbon compound metabolism, and its reverse reaction represents the first step in carbon assimilation in the acetogenic and methanogenic branches of many anaerobic organisms. The molybdenum-containing dehydrogenase FdsABG is a soluble NAD+-dependent formate dehydrogenase and a member of the NADH dehydrogenase superfamily. Here, we present the first structure of the FdsBG subcomplex of the cytosolic FdsABG formate dehydrogenase from the hydrogen-oxidizing bacterium Cupriavidus necator H16 both with and without bound NADH. The structures revealed that the two iron-sulfur clusters, Fe4S4 in FdsB and Fe2S2 in FdsG, are closer to the FMN than they are in other NADH dehydrogenases. Rapid kinetic studies and EPR measurements of rapid freeze-quenched samples of the NADH reduction of FdsBG identified a neutral flavin semiquinone, FMNH•, not previously observed to participate in NADH-mediated reduction of the FdsABG holoenzyme. We found that this semiquinone forms through the transfer of one electron from the fully reduced FMNH−, initially formed via NADH-mediated reduction, to the Fe2S2 cluster. This Fe2S2 cluster is not part of the on-path chain of iron-sulfur clusters connecting the FMN of FdsB with the active-site molybdenum center of FdsA. According to the NADH-bound structure, the nicotinamide ring stacks onto the re-face of the FMN. However, NADH binding significantly reduced the electron density for the isoalloxazine ring of FMN and induced a conformational change in residues of the FMN-binding pocket that display peptide-bond flipping upon NAD+ binding in proper NADH dehydrogenases.

JP Segrest
Feb 1, 1992; 33:141-166
Reviews

Heterotrimeric G proteins mediate a variety of signaling processes by coupling G protein–coupled receptors to intracellular effector molecules. In Drosophila, the Gαq gene encodes several Gαq splice variants, with the Gαq1 isoform protein playing a major role in fly phototransduction. However, Gαq1 null mutant flies still exhibit a residual light response, indicating that other Gαq splice variants or additional Gq α subunits are involved in phototransduction. Here, we isolated a mutant fly with no detectable light responses, decreased rhodopsin (Rh) levels, and rapid retinal degeneration. Using electrophysiological and genetic studies, biochemical assays, immunoblotting, real-time RT-PCR, and EM analysis, we found that mutations in the Gαq gene disrupt light responses and demonstrate that the Gαq3 isoform protein is responsible for the residual light response in Gαq1 null mutants. Moreover, we report that Gαq3 mediates rhodopsin synthesis. Depletion of all Gαq splice variants led to rapid light-dependent retinal degeneration, due to the formation stable Rh1-arrestin 2 (Arr2) complexes. Our findings clarify essential roles of several different Gαq splice variants in phototransduction and retinal integrity in Drosophila and reveal that Gαq3 functions in rhodopsin synthesis.

Glial cell line–derived neurotrophic factor (GDNF) is a growth factor that regulates the health and function of neurons and other cells. GDNF binds to GDNF family receptor α1 (GFRa1), and the resulting complex activates the RET receptor tyrosine kinase and subsequent downstream signals. This feature restricts GDNF activity to systems in which GFRa1 and RET are both present, a scenario that may constrain GDNF breadth of action. Furthermore, this co-dependence precludes the use of GDNF as a tool to study a putative functional cross-talk between GFRa1 and RET. Here, using biochemical techniques, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and immunohistochemistry in murine cells, tissues, or retinal organotypic cultures, we report that a naphthoquinone/quinolinedione family of small molecules (Q compounds) acts as RET agonists. We found that, like GDNF, signaling through the parental compound Q121 is GFRa1-dependent. Structural modifications of Q121 generated analogs that activated RET irrespective of GFRa1 expression. We used these analogs to examine RET–GFRa1 interactions and show that GFRa1 can influence RET-mediated signaling and enhance or diminish AKT Ser/Thr kinase or extracellular signal-regulated kinase signaling in a biased manner. In a genetic mutant model of retinitis pigmentosa, a lead compound, Q525, afforded sustained RET activation and prevented photoreceptor neuron loss in the retina. This work uncovers key components of the dynamic relationships between RET and its GFRa co-receptor and provides RET agonist scaffolds for drug development.

Hippo pathway signaling limits cell growth and proliferation and maintains the stem-cell niche. These cellular events result from the coordinated activity of a core kinase cassette that is regulated, in part, by interactions involving Hippo, Salvador, and dRassF. These interactions are mediated by a conserved coiled-coil domain, termed SARAH, in each of these proteins. SARAH domain–mediated homodimerization of Hippo kinase leads to autophosphorylation and activation. Paradoxically, SARAH domain–mediated heterodimerization between Hippo and Salvador enhances Hippo kinase activity in cells, whereas complex formation with dRassF inhibits it. To better understand the mechanism by which each complex distinctly modulates Hippo kinase and pathway activity, here we biophysically characterized the entire suite of SARAH domain–mediated complexes. We purified the three SARAH domains from Drosophila melanogaster and performed an unbiased pulldown assay to identify all possible interactions, revealing that isolated SARAH domains are sufficient to recapitulate the cellular assemblies and that Hippo is a universal binding partner. Additionally, we found that the Salvador SARAH domain homodimerizes and demonstrate that this interaction is conserved in Salvador's mammalian homolog. Using native MS, we show that each of these complexes is dimeric in solution. We also measured the stability of each SARAH domain complex, finding that despite similarities at both the sequence and structural levels, SARAH domain complexes differ in stability. The identity, stoichiometry, and stability of these interactions characterized here comprehensively reveal the nature of SARAH domain–mediated complex formation and provide mechanistic insights into how SARAH domain–mediated interactions influence Hippo pathway activity.

Formate oxidation to carbon dioxide is a key reaction in one-carbon compound metabolism, and its reverse reaction represents the first step in carbon assimilation in the acetogenic and methanogenic branches of many anaerobic organisms. The molybdenum-containing dehydrogenase FdsABG is a soluble NAD+-dependent formate dehydrogenase and a member of the NADH dehydrogenase superfamily. Here, we present the first structure of the FdsBG subcomplex of the cytosolic FdsABG formate dehydrogenase from the hydrogen-oxidizing bacterium Cupriavidus necator H16 both with and without bound NADH. The structures revealed that the two iron-sulfur clusters, Fe4S4 in FdsB and Fe2S2 in FdsG, are closer to the FMN than they are in other NADH dehydrogenases. Rapid kinetic studies and EPR measurements of rapid freeze-quenched samples of the NADH reduction of FdsBG identified a neutral flavin semiquinone, FMNH•, not previously observed to participate in NADH-mediated reduction of the FdsABG holoenzyme. We found that this semiquinone forms through the transfer of one electron from the fully reduced FMNH−, initially formed via NADH-mediated reduction, to the Fe2S2 cluster. This Fe2S2 cluster is not part of the on-path chain of iron-sulfur clusters connecting the FMN of FdsB with the active-site molybdenum center of FdsA. According to the NADH-bound structure, the nicotinamide ring stacks onto the re-face of the FMN. However, NADH binding significantly reduced the electron density for the isoalloxazine ring of FMN and induced a conformational change in residues of the FMN-binding pocket that display peptide-bond flipping upon NAD+ binding in proper NADH dehydrogenases.