A massive boom heard Wednesday night over Puget Sound on the northwestern coast of Washington was most likely an exploding meteor. Or that's what They want us to believe anyway. The American Meteor Society registered a dozen reports. Video above. Keep your eyes on the upper left of the frame.

"The more I read the more inclined I am to believe this was a fireball (which is a meteor that is larger and brighter than normal)," the American Meteor Society's Bob Lunsford said. "I'm certain now that this was a meteoric event."

From KOMONews:

Most meteors' explosions are heard about a minute or two after they explode due to the time it takes the sound to reach the Earth's surface, Lunsford said. Sound travels at 767 mph in standard atmosphere conditions, indicating this fireball exploded some 35 miles away.

"If this was larger than normal then the sound could have originated from a higher altitude. So a delay of 3 minutes is entirely possible," Lunsford said. "Meteors become visible at a height of around 50 miles so your estimate is well within that range."

Lunsford said because there was a boom, it’s very likely there are small, rock-sized pieces of the meteor somewhere on the ground. When a meteor causes a boom, it’s “pretty far down” in the atmosphere.

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The "transient bazaar" known as Lost Horizon Night Market is a covert operation. Worlds are imagined and then built inside the blank canvasses of empty box trucks. For the event, all the "proprietors," and their appointed box trucks, convene in an unsanctioned, though discreet, location. This location is disclosed to would-be "shoppers" via text just a few hours before it starts. Word of the market generally spreads rapidly but not publicly, definitely not by social media. If you're lucky enough to hear about it, you should go.

So, Happy Mutants, this is your heads up. Lost Horizon Night Market: Quarantine Edition is happening Saturday, May 9, from 6:59p EST until 11:59p EST, "rain or shine." This one is a little different, as the spaces are virtual, not in actual, physical trucks. I got a sneak peek yesterday of what's been created and can't wait to dive in deeper. Admission is free, though tips are appreciated. RSVP here.

Previously: Secret box truck 'night market' pops up again in NYC Read the rest

Canada Post's main plant in Calgary has six confirmed cases of COVID-19. That news was confirmed Friday by Dr. Deena Hinshaw at her daily update.

Six-time world champion Lewis Hamilton has said he feels "fresher than ever" following an unexpected break from Formula One.

Former Proteas head coach Ray Jennings is adamant Aiden Markram should be chosen as Faf du Plessis' replacement as captain of the Test team.

NZ Rugby CEO Mark Robinson says there is still no clarity on the prospects for Test rugby in 2020, but said they will explore every avenue.

Most Realtors® Don’t Expect Steep Price Declines in...

Every successful business expecting high returns should have investment projects. Just like any other advertisement plan, a business card is crucial. It links up your company and the potential customers easily. It’s cheaper to design and distribute the cards. However, for a startup business which is low on budget and high on initial expenses, designing […]

The post Expand Your Brand Using Business Cards appeared first on Dumb Little Man.

Spotify will gain more than 10 million US listeners in 2020   February 25, 2020 (New York, NY) – Pandora is no longer the most popular music streaming service in the […]

This is not where I thought I’d be. If things had gone to plan, I would now be on a bus moving through the Peruvian countryside, smiling at the memory of my meals at Central and Maido, looking forward to sandboarding in Huacachina, seeing Machu Picchu, and exploring the Galapagos a few weeks after that. …

Sheltering in Place in Mexico City Read More »

The post Sheltering in Place in Mexico City appeared first on Adventurous Kate.

After spending two months living in Mérida and years of trips traveling through the Yucatán Peninsula, I’ve finally put together the best itinerary for two weeks in Mexico. Most travelers go to Mexico to lie on the beach for a week, maybe go on an excursion to a ruin or a cenote, and head straight …

Two Weeks in Mexico: The BEST Yucatán Road Trip Itinerary Read More »

The post Two Weeks in Mexico: The BEST Yucatán Road Trip Itinerary appeared first on Adventurous Kate.

Part of the Antarctic diary promo for the BBC UK Homepage

A couple weeks ago, my pals at Twitter were kind enough to invite me in to visit with their (rapidly growing) team. The topic was meetings, so I used it as an opportunity to publicly premiere a talk I've been presenting to private clients over the past few months.

I hope you'll enjoy, Broken Meetings (and how you'll fix them).

Slides:

Supplementary links and commentary forthcoming, but I wanted to go ahead and post the talk as quickly as the video was available. Special thanks to Michelle, Jeremy, and the crackerjack Twitter crew for a swell afternoon.

I really like this talk and sincerely hope you will find it useful in helping to un-break your own meetings.

The DML News App offers the best in news reporting.

The post JUST IN: Actress and leader of #MeToo movement accuses Bill Maher of sexually harassing her appeared first on Dennis Michael Lynch.

The Ontario government gave garden centres and nurseries the green light to open their doors to the public on Friday.

The following article, BREAKING: 43-Yr-Old Father Of 9, Dollar Store Sec Guard, Shot DEAD While Allegedly Trying To Enforce MI Gov Whitmer’s Face Covering Exec Order, was first published on 100PercentFedUp.com.

Will the mainstream media report about the senseless death of a 43-year-old father of nine, who would have been alive today if it were not for VP wannabe, Gretchen Whitmer's executive order that forced him to respond to a customer not wearing a face mask? 

Continue reading: BREAKING: 43-Yr-Old Father Of 9, Dollar Store Sec Guard, Shot DEAD While Allegedly Trying To Enforce MI Gov Whitmer’s Face Covering Exec Order ...

The following article, NY Shame: Workers Who Tested Positive For COVID-19 Were Allowed To Remain On The Job At Nursing Homes, As Death Toll For Nursing Home Patients Exceeds 3,000, was first published on 100PercentFedUp.com.

The coronavirus crisis at New York’s nursing homes is even worse than previously thought. Monday night, the state Department of Health issued new data, adding more than 1,600 people who were presumed to have died of the virus in nursing homes, but did not have a confirmed diagnosis, to the official toll. As of May […]

Continue reading: NY Shame: Workers Who Tested Positive For COVID-19 Were Allowed To Remain On The Job At Nursing Homes, As Death Toll For Nursing Home Patients Exceeds 3,000 ...

The following article, Breaking: Texas AG Calls for Immediate Release of Salon Owner Jailed for Opening…Texas Lt Gov Offers to Pay Salon Owner’s $7k Fine, was first published on 100PercentFedUp.com.

Salon A La Mode owner Shelley Luther opened her salon in defiance of the lockdown order for salons to stay closed during the coronavirus crisis. She boldly ripped. up the citation she was given by the police and refused to shut her doors. Luther hired a lawyer and went to court where an activist judge […]

Continue reading: Breaking: Texas AG Calls for Immediate Release of Salon Owner Jailed for Opening…Texas Lt Gov Offers to Pay Salon Owner’s $7k Fine ...

The following article, Texas Gov Abbott Frees Salon Owner Shelley Luther: “Criminals shouldn’t be released to prevent COVID-19 just to put business owners in their place”, was first published on 100PercentFedUp.com.

Texas Governor Greg Abbott just changed the coronavirus order to free Salon A La Mode owner Shelley Luther from jail. Abbott tweeted out a comment about the poor treatment of the business owner: Throwing Texans in jail whose biz’s shut down through no fault of their own is wrong. I am eliminating jail for violating […]

Continue reading: Texas Gov Abbott Frees Salon Owner Shelley Luther: “Criminals shouldn’t be released to prevent COVID-19 just to put business owners in their place” ...

The following article, BREAKING: Michigan’s Radical Governor Extends Lockdown AGAIN…Only One Day After Church Leaders and MI Lawmakers File Suit Against Her, was first published on 100PercentFedUp.com.

Michigan was the first state to see protests against draconian lockdown measures by an overreaching governor. On April 15, the Michigan Conservative Coalition organized an in-vehicle protest in Lansing, MI that drew an estimated 15,000 vehicles. Since that time, several protests by Michigan workers who are being devastated by the one-size-fits-all shut down of the […]

Continue reading: BREAKING: Michigan’s Radical Governor Extends Lockdown AGAIN…Only One Day After Church Leaders and MI Lawmakers File Suit Against Her ...

The following article, Mother of the Year, Michelle Obama Explains How Having Kids Was A “Concession”… Had To Give Up Her “Aspirations and Dreams” [VIDEO], was first published on 100PercentFedUp.com.

While campaigning for her community organizer turned presidential candidate husband, Barack, Michelle Obama told a crowd of his supporters in Milwaukee, Wisconsin that for the first time in her life, she was proud to be an American. Four years later, Michelle Obama was a keynote speaker at the DNC convention, where she told Democrats how […]

Continue reading: Mother of the Year, Michelle Obama Explains How Having Kids Was A “Concession”… Had To Give Up Her “Aspirations and Dreams” [VIDEO] ...

The following article, BREAKING: Ex-Cop Father and Son Arrested and Charged With Murder of Black Man Jogging In Neighborhood…President Trump Responds [VIDEO], was first published on 100PercentFedUp.com.

The Georgia Bureau of Investigations has arrested a father and son duo, 64-year-old ex-cop, Gregory McMichael, and his son, 34-year-old Travis McMichael for the February murder of  24-year-old Ahmaud Arbery, a black man who was jogging through their neighborhood when they jumped in their truck and pursued him. Yashar Ali shared the news of the […]

Continue reading: BREAKING: Ex-Cop Father and Son Arrested and Charged With Murder of Black Man Jogging In Neighborhood…President Trump Responds [VIDEO] ...

The following article, BREAKING: New Docs Prove Obama Knew Details Of Flynn Wiretapping…Newly Surfaced Video Shows Obama Explaining How He Stays Out Of FBI Investigations, was first published on 100PercentFedUp.com.

Barack Obama knew. Documents released yesterday that were used to exonerate President Trump’s new NSA General Flynn, prove that President Barack Obama was aware of the details of Michael Flynn’s intercepted phone calls on December 16 with then-Russian Ambassador Sergey Kislyak. On January 5, 2017, then-Deputy Attorney General, Sally Yates attended an Oval Office meeting […]

Continue reading: BREAKING: New Docs Prove Obama Knew Details Of Flynn Wiretapping…Newly Surfaced Video Shows Obama Explaining How He Stays Out Of FBI Investigations ...

The following article, BREAKING: President Trump’s Fiery Interview On Fox & Friends…”These are dirty politicians and dirty cops…They put our nation in danger with other nations, including Russia” [VIDEO], was first published on 100PercentFedUp.com.

This morning during a nearly one hour interview with Fox & Friends, President Trump addressed the decision by the DOJ to drop the case against the innocent General Michael Flynn. Trump ripped into the “dirty politicians and dirty cops” who went after General Michael Flynn. President Trump called the players involved in the horrible plot […]

Continue reading: BREAKING: President Trump’s Fiery Interview On Fox & Friends…”These are dirty politicians and dirty cops…They put our nation in danger with other nations, including Russia” [VIDEO] ...

The following article, Fed Judge Releases 21-Yr-Old Man To “Clean and Sober House” After Appearing In Court For Sexually Assaulting 12-Yr-Old Girl For One Month While Hiding In Her Bedroom, was first published on 100PercentFedUp.com.

The normalizing of pedophilia is not a far-right conspiracy theory...

Continue reading: Fed Judge Releases 21-Yr-Old Man To “Clean and Sober House” After Appearing In Court For Sexually Assaulting 12-Yr-Old Girl For One Month While Hiding In Her Bedroom ...

One more person has died from the coronavirus in the Windsor-Essex region on Saturday and nine new cases have been reported by the health unit.

Environment Canada has issued a special weather statement for the southwestern area of Manitoba.

Research Event

Event participants

Professor Jagjit S. Chadha, Director, NIESR
Dr Kamala Dawar, Senior Lecturer in Law, University of Sussex; Fellow, UKTPO
Dr Michael Gasiorek, Senior Lecturer in Economics, University of Sussex; Director, Interanalysis; Fellow, UKTPO
Chair: Professor Jim Rollo, Deputy Director, UKTPO; Associate Fellow, Chatham House

Telomeres are specific nucleoprotein structures that are located at the ends of linear eukaryotic chromosomes and play crucial roles in genomic stability. Telomere DNA consists of simple repeats of a short G-rich sequence: TTAGGG in mammals and TTTAGGG in most plants. In recent years, the mammalian telomeric G-rich repeats have been shown to form G-quadruplex (G4) structures, which are crucial for modulating telomere functions. Surprisingly, even though plant telomeres are essential for plant growth, development, and environmental adaptions, only few reports exist on plant telomeric G4 DNA (pTG4). Here, using bulk and single-molecule assays, including CD spectroscopy, and single-molecule FRET approaches, we comprehensively characterized the structure and dynamics of a typical plant telomeric sequence, d[GGG(TTTAGGG)3]. We found that this sequence can fold into mixed G4s in potassium, including parallel and antiparallel structures. We also directly detected intermediate dynamic transitions, including G-hairpin, parallel G-triplex, and antiparallel G-triplex structures. Moreover, we observed that pTG4 is unfolded by the AtRecQ2 helicase but not by AtRecQ3. The results of our work shed light on our understanding about the existence, topological structures, stability, intermediates, unwinding, and functions of pTG4.

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 transcription factor forkhead box P3 (FOXP3) is a biomarker for regulatory T cells and can also be expressed in cancer cells, but its function in cancer appears to be divergent. The role of hepatocyte-expressed FOXP3 in hepatocellular carcinoma (HCC) is unknown. Here, we collected tumor samples and clinical information from 115 HCC patients and used five human cancer cell lines. We examined FOXP3 mRNA sequences for mutations, used a luciferase assay to assess promoter activities of FOXP3's target genes, and employed mouse tumor models to confirm in vitro results. We detected mutations in the FKH domain of FOXP3 mRNAs in 33% of the HCC tumor tissues, but in none of the adjacent nontumor tissues. None of the mutations occurred at high frequency, indicating that they occurred randomly. Notably, the mutations were not detected in the corresponding regions of FOXP3 genomic DNA, and many of them resulted in amino acid substitutions in the FKH region, altering FOXP3's subcellular localization. FOXP3 delocalization from the nucleus to the cytoplasm caused loss of transcriptional regulation of its target genes, inactivated its tumor-inhibitory capability, and changed cellular responses to histone deacetylase (HDAC) inhibitors. More complex FKH mutations appeared to be associated with worse prognosis in HCC patients. We conclude that mutations in the FKH domain of FOXP3 mRNA frequently occur in HCC and that these mutations are caused by errors in transcription and are not derived from genomic DNA mutations. Our results suggest that transcriptional mutagenesis of FOXP3 plays a role in HCC.

Prostate cancer (PCa) cells heavily rely on an active androgen receptor (AR) pathway for their survival. Enzalutamide (MDV3100) is a second-generation antiandrogenic drug that was approved by the Food and Drug Administration in 2012 to treat patients with castration-resistant prostate cancer (CRPC). However, emergence of resistance against this drug is inevitable, and it has been a major challenge to develop interventions that help manage enzalutamide-resistant CRPC. Erythropoietin-producing human hepatocellular (Eph) receptors are targeted by ephrin protein ligands and have a broad range of functions. Increasing evidence indicates that this signaling pathway plays an important role in tumorigenesis. Overexpression of EPH receptor B4 (EPHB4) has been observed in multiple types of cancer, being closely associated with proliferation, invasion, and metastasis of tumors. Here, using RNA-Seq analyses of clinical and preclinical samples, along with several biochemical and molecular methods, we report that enzalutamide-resistant PCa requires an active EPHB4 pathway that supports drug resistance of this tumor type. Using a small kinase inhibitor and RNAi-based gene silencing to disrupt EPHB4 activity, we found that these disruptions re-sensitize enzalutamide-resistant PCa to the drug both in vitro and in vivo. Mechanistically, we found that EPHB4 stimulates the AR by inducing proto-oncogene c-Myc (c-Myc) expression. Taken together, these results provide critical insight into the mechanism of enzalutamide resistance in PCa, potentially offering a therapeutic avenue for enhancing the efficacy of enzalutamide to better manage this common malignancy.

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.

The Mycobacterium tuberculosis virulence factor EsxA and its chaperone EsxB are secreted as a heterodimer (EsxA:B) and are crucial for mycobacterial escape from phagosomes and cytosolic translocation. Current findings support the idea that for EsxA to interact with host membranes, EsxA must dissociate from EsxB at low pH. However, the molecular mechanism by which the EsxA:B heterodimer separates is not clear. In the present study, using liposome-leakage and cytotoxicity assays, LC-MS/MS–based proteomics, and CCF-4 FRET analysis, we obtained evidence that the Nα-acetylation of the Thr-2 residue on EsxA, a post-translational modification that is present in mycobacteria but absent in Escherichia coli, is required for the EsxA:B separation. Substitutions at Thr-2 that precluded Nα-acetylation inhibited the heterodimer separation and hence prevented EsxA from interacting with the host membrane, resulting in attenuated mycobacterial cytosolic translocation and virulence. Molecular dynamics simulations revealed that at low pH, the Nα-acetylated Thr-2 makes direct and frequent “bind-and-release” contacts with EsxB, which generates a force that pulls EsxB away from EsxA. In summary, our findings provide evidence that the Nα-acetylation at Thr-2 of EsxA facilitates dissociation of the EsxA:B heterodimer required for EsxA membrane permeabilization and mycobacterial cytosolic translocation and virulence.

The protein-tyrosine phosphatase SHP2 is an allosteric enzyme critical for cellular events downstream of growth factor receptors. Mutations in the SHP2 gene have been linked to many different types of human diseases, including developmental disorders, leukemia, and solid tumors. Unlike most SHP2-activating mutations, the T507K substitution in SHP2 is unique in that it exhibits oncogenic Ras-like transforming activity. However, the biochemical basis of how the SHP2/T507K variant elicits transformation remains unclear. By combining kinetic and biophysical methods, X-ray crystallography, and molecular modeling, as well as using cell biology approaches, here we uncovered that the T507K substitution alters both SHP2 substrate specificity and its allosteric regulatory mechanism. We found that although SHP2/T507K exists in the closed, autoinhibited conformation similar to the WT enzyme, the interactions between its N-SH2 and protein-tyrosine phosphatase domains are weakened such that SHP2/T507K possesses a higher affinity for the scaffolding protein Grb2-associated binding protein 1 (Gab1). We also discovered that the T507K substitution alters the structure of the SHP2 active site, resulting in a change in SHP2 substrate preference for Sprouty1, a known negative regulator of Ras signaling and a potential tumor suppressor. Our results suggest that SHP2/T507K's shift in substrate specificity coupled with its preferential association of SHP2/T507K with Gab1 enable the mutant SHP2 to more efficiently dephosphorylate Sprouty1 at pTyr-53. This dephosphorylation hyperactivates Ras signaling, which is likely responsible for SHP2/T507K's Ras-like transforming activity.

Bacterial type VII secretion systems secrete a wide range of extracellular proteins that play important roles in bacterial viability and in interactions of pathogenic mycobacteria with their hosts. Mycobacterial type VII secretion systems consist of five subtypes, ESX-1–5, and have four substrate classes, namely, Esx, PE, PPE, and Esp proteins. At least some of these substrates are secreted as heterodimers. Each ESX system mediates the secretion of a specific set of Esx, PE, and PPE proteins, raising the question of how these substrates are recognized in a system-specific fashion. For the PE/PPE heterodimers, it has been shown that they interact with their cognate EspG chaperone and that this chaperone determines the designated secretion pathway. However, both structural and pulldown analyses have suggested that EspG cannot interact with the Esx proteins. Therefore, the determining factor for system specificity of the Esx proteins remains unknown. Here, we investigated the secretion specificity of the ESX-1 substrate pair EsxB_1/EsxA_1 in Mycobacterium marinum. Although this substrate pair was hardly secreted when homologously expressed, it was secreted when co-expressed together with the PE35/PPE68_1 pair, indicating that this pair could stimulate secretion of the EsxB_1/EsxA_1 pair. Surprisingly, co-expression of EsxB_1/EsxA_1 with a modified PE35/PPE68_1 version that carried the EspG5 chaperone-binding domain, previously shown to redirect this substrate pair to the ESX-5 system, also resulted in redirection and co-secretion of the Esx pair via ESX-5. Our results suggest a secretion model in which PE35/PPE68_1 determines the system-specific secretion of EsxB_1/EsxA_1.

Assembled α-synuclein in nerve cells and glial cells is the defining pathological feature of neurodegenerative diseases called synucleinopathies. Seeds of α-synuclein can induce the assembly of monomeric protein. Here, we used sucrose gradient centrifugation and transiently transfected HEK 293T cells to identify the species of α-synuclein from the brains of homozygous, symptomatic mice transgenic for human mutant A53T α-synuclein (line M83) that seed aggregation. The most potent fractions contained Sarkosyl-insoluble assemblies enriched in filaments. We also analyzed six cases of idiopathic Parkinson's disease (PD), one case of familial PD, and six cases of multiple system atrophy (MSA) for their ability to induce α-synuclein aggregation. The MSA samples were more potent than those of idiopathic PD in seeding aggregation. We found that following sucrose gradient centrifugation, the most seed-competent fractions from PD and MSA brains are those that contain Sarkosyl-insoluble α-synuclein. The fractions differed between PD and MSA, consistent with the presence of distinct conformers of assembled α-synuclein in these different samples. We conclude that α-synuclein filaments are the main driving force for amplification and propagation of pathology in synucleinopathies.

Interferon-regulated myxovirus resistance protein B (MxB) is an interferon-induced GTPase belonging to the dynamin superfamily. It inhibits infection with a wide range of different viruses, including HIV-1, by impairing viral DNA entry into the nucleus. Unlike the related antiviral GTPase MxA, MxB possesses an N-terminal region that contains a nuclear localization signal and is crucial for inhibiting HIV-1. Because MxB previously has been shown to reside in both the nuclear envelope and the cytoplasm, here we used bioinformatics and biochemical approaches to identify a nuclear export signal (NES) responsible for MxB's cytoplasmic location. Using the online computational tool LocNES (Locating Nuclear Export Signals or NESs), we identified five putative NES candidates in MxB and investigated whether their deletion caused nuclear localization of MxB. Our results revealed that none of the five deletion variants relocates to the nucleus, suggesting that these five predicted NES sequences do not confer NES activity. Interestingly, deletion of one sequence, encompassing amino acids 505–527, abrogated the anti-HIV-1 activity of MxB. Further mutation experiments disclosed that amino acids 515–519, and Pro-515 in particular, regulate MxB oligomerization and its binding to HIV-1 capsid, thereby playing an important role in MxB-mediated restriction of HIV-1 infection. In summary, our results indicate that none of the five predicted NES sequences in MxB appears to be required for its nuclear export. Our findings also reveal several residues in MxB, including Pro-515, critical for its oligomerization and anti-HIV-1 function.

Carbon monoxide (CO) remains the most common cause of human poisoning. The consequences of CO poisoning include cardiac dysfunction, brain injury, and death. CO causes toxicity by binding to hemoglobin and by inhibiting mitochondrial cytochrome c oxidase (CcO), thereby decreasing oxygen delivery and inhibiting oxidative phosphorylation. We have recently developed a CO antidote based on human neuroglobin (Ngb-H64Q-CCC). This molecule enhances clearance of CO from red blood cells in vitro and in vivo. Herein, we tested whether Ngb-H64Q-CCC can also scavenge CO from CcO and attenuate CO-induced inhibition of mitochondrial respiration. Heart tissue from mice exposed to 3% CO exhibited a 42 ± 19% reduction in tissue respiration rate and a 33 ± 38% reduction in CcO activity compared with unexposed mice. Intravenous infusion of Ngb-H64Q-CCC restored respiration rates to that of control mice correlating with higher electron transport chain CcO activity in Ngb-H64Q-CCC–treated compared with PBS-treated, CO-poisoned mice. Further, using a Clark-type oxygen electrode, we measured isolated rat liver mitochondrial respiration in the presence and absence of saturating solutions of CO (160 μm) and nitric oxide (100 μm). Both CO and NO inhibited respiration, and treatment with Ngb-H64Q-CCC (100 and 50 μm, respectively) significantly reversed this inhibition. These results suggest that Ngb-H64Q-CCC mitigates CO toxicity by scavenging CO from carboxyhemoglobin, improving systemic oxygen delivery and reversing the inhibitory effects of CO on mitochondria. We conclude that Ngb-H64Q-CCC or other CO scavengers demonstrate potential as antidotes that reverse the clinical and molecular effects of CO poisoning.

Manganese (Mn) is an essential micronutrient required for the normal development of many organs, including the brain. Although its roles as a cofactor in several enzymes and in maintaining optimal physiology are well-known, the overall biological functions of Mn are rather poorly understood. Alterations in body Mn status are associated with altered neuronal physiology and cognition in humans, and either overexposure or (more rarely) insufficiency can cause neurological dysfunction. The resultant balancing act can be viewed as a hormetic U-shaped relationship for biological Mn status and optimal brain health, with changes in the brain leading to physiological effects throughout the body and vice versa. This review discusses Mn homeostasis, biomarkers, molecular mechanisms of cellular transport, and neuropathological changes associated with disruptions of Mn homeostasis, especially in its excess, and identifies gaps in our understanding of the molecular and biochemical mechanisms underlying Mn homeostasis and neurotoxicity.

Treatment of patients with triple-negative breast cancer (TNBC) is limited by a lack of effective molecular therapies targeting this disease. Recent studies have identified metabolic alterations in cancer cells that can be targeted to improve responses to standard-of-care chemotherapy regimens. Using MDA-MB-468 and SUM-159PT TNBC cells, along with LC-MS/MS and HPLC metabolomics profiling, we found here that exposure of TNBC cells to the cytotoxic chemotherapy drugs cisplatin and doxorubicin alter arginine and polyamine metabolites. This alteration was because of a reduction in the levels and activity of a rate-limiting polyamine biosynthetic enzyme, ornithine decarboxylase (ODC). Using gene silencing and inhibitor treatments, we determined that the reduction in ODC was mediated by its negative regulator antizyme, targeting ODC to the proteasome for degradation. Treatment with the ODC inhibitor difluoromethylornithine (DFMO) sensitized TNBC cells to chemotherapy, but this was not observed in receptor-positive breast cancer cells. Moreover, TNBC cell lines had greater sensitivity to single-agent DFMO, and ODC levels were elevated in TNBC patient samples. The alterations in polyamine metabolism in response to chemotherapy, as well as DFMO-induced preferential sensitization of TNBC cells to chemotherapy, reported here suggest that ODC may be a targetable metabolic vulnerability in TNBC.

20 November 2019

26 February 2020

Over the past two decades, China has increased its presence in North Africa in terms of trade and investment. This paper looks at China’s policy within the context of its Africa and Middle East policies to better understand its approach to Morocco and Tunisia.

Neoantimycins are anticancer compounds of 15-membered ring antimycin-type depsipeptides. They are biosynthesized by a hybrid multimodular protein complex of nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS), typically from the starting precursor 3-formamidosalicylate. Examining fermentation extracts of Streptomyces conglobatus, here we discovered four new neoantimycin analogs, unantimycins B–E, in which 3-formamidosalicylates are replaced by an unusual 3-hydroxybenzoate (3-HBA) moiety. Unantimycins B–E exhibited levels of anticancer activities similar to those of the chemotherapeutic drug cisplatin in human lung cancer, colorectal cancer, and melanoma cells. Notably, they mostly displayed no significant toxicity toward noncancerous cells, unlike the serious toxicities generally reported for antimycin-type natural products. Using site-directed mutagenesis and heterologous expression, we found that unantimycin productions are correlated with the activity of a chorismatase homolog, the nat-hyg5 gene, from a type I PKS gene cluster. Biochemical analysis confirmed that the catalytic activity of Nat-hyg5 generates 3-HBA from chorismate. Finally, we achieved selective production of unantimycins B and C by engineering a chassis host. On the basis of these findings, we propose that unantimycin biosynthesis is directed by the neoantimycin-producing NRPS–PKS complex and initiated with the starter unit of 3-HBA. The elucidation of the biosynthetic unantimycin pathway reported here paves the way to improve the yield of these compounds for evaluation in oncotherapeutic applications.

The formation of translationally inactive 70S dimers (called 100S ribosomes) by hibernation-promoting factor is a widespread survival strategy among bacteria. Ribosome dimerization is thought to be reversible, with the dissociation of the 100S complexes enabling ribosome recycling for participation in new rounds of translation. The precise pathway of 100S ribosome recycling has been unclear. We previously found that the heat-shock GTPase HflX in the human pathogen Staphylococcus aureus is a minor disassembly factor. Cells lacking hflX do not accumulate 100S ribosomes unless they are subjected to heat exposure, suggesting the existence of an alternative pathway during nonstressed conditions. Here, we provide biochemical and genetic evidence that two essential translation factors, ribosome-recycling factor (RRF) and GTPase elongation factor G (EF-G), synergistically split 100S ribosomes in a GTP-dependent but tRNA translocation-independent manner. We found that although HflX and the RRF/EF-G pair are functionally interchangeable, HflX is expressed at low levels and is dispensable under normal growth conditions. The bacterial RRF/EF-G pair was previously known to target only the post-termination 70S complexes; our results reveal a new role in the reversal of ribosome hibernation that is intimately linked to bacterial pathogenesis, persister formation, stress responses, and ribosome integrity.

Bacterial type VII secretion systems secrete a wide range of extracellular proteins that play important roles in bacterial viability and in interactions of pathogenic mycobacteria with their hosts. Mycobacterial type VII secretion systems consist of five subtypes, ESX-1–5, and have four substrate classes, namely, Esx, PE, PPE, and Esp proteins. At least some of these substrates are secreted as heterodimers. Each ESX system mediates the secretion of a specific set of Esx, PE, and PPE proteins, raising the question of how these substrates are recognized in a system-specific fashion. For the PE/PPE heterodimers, it has been shown that they interact with their cognate EspG chaperone and that this chaperone determines the designated secretion pathway. However, both structural and pulldown analyses have suggested that EspG cannot interact with the Esx proteins. Therefore, the determining factor for system specificity of the Esx proteins remains unknown. Here, we investigated the secretion specificity of the ESX-1 substrate pair EsxB_1/EsxA_1 in Mycobacterium marinum. Although this substrate pair was hardly secreted when homologously expressed, it was secreted when co-expressed together with the PE35/PPE68_1 pair, indicating that this pair could stimulate secretion of the EsxB_1/EsxA_1 pair. Surprisingly, co-expression of EsxB_1/EsxA_1 with a modified PE35/PPE68_1 version that carried the EspG5 chaperone-binding domain, previously shown to redirect this substrate pair to the ESX-5 system, also resulted in redirection and co-secretion of the Esx pair via ESX-5. Our results suggest a secretion model in which PE35/PPE68_1 determines the system-specific secretion of EsxB_1/EsxA_1.

Nucleoside analogues are a valuable experimental tool. Incorporation of these molecules into newly synthesized DNA (i.e. pulse-labeling) is used to monitor cell proliferation or to isolate nascent DNA. Some of the most common nucleoside analogues used for pulse-labeling of DNA in cells are the deoxypyrimidine analogues 5-ethynyl-2'-deoxyuridine (EdU) and 5-ethynyl-2'-deoxycytidine (EdC). Click chemistry enables conjugation of an azide molecule tagged with a fluorescent dye or biotin to the alkyne of the analog, which can then be used to detect incorporation of EdU and EdC into DNA. The use of EdC is often recommended because of the potential cytotoxicity associated with EdU during longer incubations. Here, by comparing the relative incorporation efficiencies of EdU and EdC during short 30-min pulses, we demonstrate significantly lower incorporation of EdC than of EdU in noninfected human fibroblast cells or in cells infected with either human cytomegalovirus or Kaposi's sarcoma-associated herpesvirus. Interestingly, cells infected with herpes simplex virus type-1 (HSV-1) incorporated EdC and EdU at similar levels during short pulses. Of note, exogenous expression of HSV-1 thymidine kinase increased the incorporation efficiency of EdC. These results highlight the limitations when using substituted pyrimidine analogues in pulse-labeling and suggest that EdU is the preferable nucleoside analogue for short pulse-labeling experiments, resulting in increased recovery and sensitivity for downstream applications. This is an important discovery that may help to better characterize the biochemical properties of different nucleoside analogues with a given kinase, ultimately leading to significant differences in labeling efficiency of nascent DNA.

Type IV filaments (T4F), which are helical assemblies of type IV pilins, constitute a superfamily of filamentous nanomachines virtually ubiquitous in prokaryotes that mediate a wide variety of functions. The competence (Com) pilus is a widespread T4F, mediating DNA uptake (the first step in natural transformation) in bacteria with one membrane (monoderms), an important mechanism of horizontal gene transfer. Here, we report the results of genomic, phylogenetic, and structural analyses of ComGC, the major pilin subunit of Com pili. By performing a global comparative analysis, we show that Com pili genes are virtually ubiquitous in Bacilli, a major monoderm class of Firmicutes. This also revealed that ComGC displays extensive sequence conservation, defining a monophyletic group among type IV pilins. We further report ComGC solution structures from two naturally competent human pathogens, Streptococcus sanguinis (ComGCSS) and Streptococcus pneumoniae (ComGCSP), revealing that this pilin displays extensive structural conservation. Strikingly, ComGCSS and ComGCSP exhibit a novel type IV pilin fold that is purely helical. Results from homology modeling analyses suggest that the unusual structure of ComGC is compatible with helical filament assembly. Because ComGC displays such a widespread distribution, these results have implications for hundreds of monoderm species.

Interferon-regulated myxovirus resistance protein B (MxB) is an interferon-induced GTPase belonging to the dynamin superfamily. It inhibits infection with a wide range of different viruses, including HIV-1, by impairing viral DNA entry into the nucleus. Unlike the related antiviral GTPase MxA, MxB possesses an N-terminal region that contains a nuclear localization signal and is crucial for inhibiting HIV-1. Because MxB previously has been shown to reside in both the nuclear envelope and the cytoplasm, here we used bioinformatics and biochemical approaches to identify a nuclear export signal (NES) responsible for MxB's cytoplasmic location. Using the online computational tool LocNES (Locating Nuclear Export Signals or NESs), we identified five putative NES candidates in MxB and investigated whether their deletion caused nuclear localization of MxB. Our results revealed that none of the five deletion variants relocates to the nucleus, suggesting that these five predicted NES sequences do not confer NES activity. Interestingly, deletion of one sequence, encompassing amino acids 505–527, abrogated the anti-HIV-1 activity of MxB. Further mutation experiments disclosed that amino acids 515–519, and Pro-515 in particular, regulate MxB oligomerization and its binding to HIV-1 capsid, thereby playing an important role in MxB-mediated restriction of HIV-1 infection. In summary, our results indicate that none of the five predicted NES sequences in MxB appears to be required for its nuclear export. Our findings also reveal several residues in MxB, including Pro-515, critical for its oligomerization and anti-HIV-1 function.

Chatham House and Routledge, Taylor & Francis are launching the Journal of Cyber Policy on 2 July.