bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phloretin Overcomes Sorafenib Resistance in Hepatocellular Carcinoma Through Targeting SHP‐1‐and STAT3 Pathways
Authors: Korashy Hesham M. , Saraswati Sarita , Abdelgadir Abdelgalil M. , Tanwer Pooja 
Published: April 2020

Hepatocellular carcinoma (HCC) is the fifth leading cause of cancer death worldwide. Sorafenib (Sor), a tyrosine kinase inhibitor, is first targeted drug approved for HCC. Although, Sor prolongs survival time with limited side effects, many HCC patients become resistant to Sor. Modulation of the Signal Transducer and Activator of Transcription 3 (STAT3) and Src homology region 2 domain‐containing phosphatase‐1 (SHP‐1) pathways are believed to mediate Sor resistance. Thus, identifying effective molecules that could revert the Sor resistance in HCC is a need. Among these promising molecules, Phloretin (PH), a dihydrochalcone flavonoid found in fruit, leaves, and roots of apple tree, possesses anticancer, antitumor, and hepatoprotective effects. However, the effects and potential mechanisms of PH remain elusive.To test our objectives, several HCC cells were tested in vitro for sensitivity to PH, Sor or both and the apoptosis, signal transduction and phosphatase activity were analyzed. The direct role of SHP‐1 was determined using chemical inhibitor and genetic SHP‐1 siRNA knock down. In vivo studies were conducted using Sor‐sensitive and ‐resistant HepG2 and Huh7 xenografts. The animal studies were conducted in conformance with the FASEB Statement of Principles for the use of animals in research and education.The present results showed that PH inhibited cell growth and induced apoptosis in HCC cells by upregulating SHP‐1 expression and downregulating STAT3 activity. PH activated SHP‐1 by disruption of auto‐inhibition of SHP‐1, leading to reduced p‐STAT3Tyr705 level. Inhibiting SHP‐1 expression and activity using specific inhibitor, PTP inhibitor III, or siRNA upregulates p‐STAT3 and counteracted the anti‐proliferative activity of PH. Furthermore, PH induced apoptosis in two Sor‐resistant HCC cell lines and attenuated STAT3‐dependent Sor resistance in HCCs. PH markedly inhibited tumor growth in both Sor‐sensitive and Sor‐resistant xenografts in vivo by impairing angiogenesis, cell proliferation and inducing apoptosis.In conclusion, the current data demonstrated that PH inhibits STAT3 activity in Sor‐sensitive and ‐resistant HCCs via SHP‐1–dependent mechanism (Fig.
1). Our results clearly indicate that PH may be a potent reagent for hepatocellular carcinoma and a novel targeted therapy for further clinical investigations.Support or Funding InformationQatar University, Qatar National Library, and King Saud UniversityGraphical abstractFigure 1
PGC1α alleviates mitochondrial dysfunction via TFEB‐mediated autophagy in acute kidney injury mice
Authors: Yuan Longhui , Yuan Yujia , Zhu Lingling , Chen Younan , Cheng Jinqiu , Lu Yanrong 
Published: April 2020

ObjectiveCisplatin is a widely used chemotherapy drug, and always led to nephrotoxicity via causing mitochondrial dysfunction. PGC‐1α, a regulator of mitochondrial biogenesis, has been recently reported to activate TFEB‐mediated autophagy, which could remove damaged mitochondria. However, The role of PGC1α/TFEB pathway remains unknown in AKI. Thus, we aim to investigate whether the activator of PGC‐1α (ZLN005) could alleviate mitochondria dysfunction though TFEB‐mediated autophagy in AKI mice.MethodsMice were administered cisplatin (16mg/kg, a single i.p. injection) to induce AKI, then treated with PBS or ZLN005 for 4 days. In vitro, HK2 cells were treated with cisplatin 5mM in the presence or absence of ZLN005.ResultsIn vivo, comparing with the normal mice, BUN and Crea were significantly increased in AKI mice, while decreased after ZLN005 treatment (Fig.
1A). Additionally, the severity of tubular injury as determined by histologic examination was markedly ameliorated in AKI+ZLN005 group (Fig.
1B), indicating that the activation of PGC‐1α could alleviate kidney injury in AKI mice. Moreover, comparing with the AKI mice, mitochondrial fragmentation (many swollen, small and round mitochondria) induced by cisplatin was decreased after ZLN005 treatment (Fig.
1C). Consistent with the observation in vivo, along with the improvement of mitochondrial function (Fig.
2A–C), ZLN005 activated TFEB‐autophagy in cisplatin‐induced HK2 cells (Fig.
2D). Whereas, the protective effect of ZLN005 was largely abolished when the expression of TFEB was inhibited by RNAi of TFEB(Fig.
2E).ConclusionThese results indicated that PGC‐1α could alleviate mitochondrial function and cisplatin‐induced kidney injury via TFEB‐autophagy pathway.Support or Funding InformationThis work was supported by the National Natural Science Foundation of China (No. 81900666)Figure 1Figure 2
Effects of Acute SGLT2 Blockade and Dietary NaCl on Glomerular Hemodynamics in Diabetic Rats
Authors: Thomson Scott Culver , Vallon Volker 
Published: April 2020

Inhibitors of the main proximal tubular Na‐glucose cotransporter (SGLT2) mitigate diabetic glomerular hyperfiltration and are approved by FDA for slowing the progression of diabetic kidney disease. It has been proposed that SGLT2 inhibitors improve hard renal outcomes by reducing the glomerular capillary pressure gradient (ΔP) through TGF signaling, which begins with a decrease in fluid reabsorption by the proximal tubule (Jprox). However, the effect of SGLT2 inhibition on ΔP has not been measured up to now.We studied effects of acute SGLT2 blockade (ertugliflozin) on Jprox and glomerular hemodynamics by 2‐period micropuncture in STZ‐diabetic rats fed high or low NaCl diets (HS/LS). ΔP was measured by direct capillary puncture in Wistar Froemter rats (MWF), which have surface glomeruli suitable for this purpose. ΔP was computed from tubular stop‐flow pressure in Wistar rats (Wis), which lack surface glomeruli. Hence, TGF was allowed to operate normally while measuring ΔP in MWF but rendered inoperative while measuring ΔP in Wis. SGLT2 blockade was confirmed to reduce Jprox by collecting fluid from late proximal tubules for volume and inulin clearance.Summary and Conclusions about the diabetic kidney under conditions of moderate hyperglycemia: SGLT2 blockade acutely reduces Jprox, which leads to a decrease in glomerular capillary pressure, but only when TGF is permitted to operate normally. Baseline glomerular capillary pressure varies inversely with dietary NaCl and the impact of SGLT2 blockade applies across a wide range of dietary NaCl.Support or Funding InformationNIDDK RO1 DK112042 Merck

Group (n)

Glucose (mg/dl)

GFR(ml/min)

ΔP (mmHg)

Jprox' (nl/min)

control

SGLT2 blocked

control

SGLT2 blocked

control

SGLT2 blocked

MWF LS (6)

344±41

4.2±0.5

3.5±0.5

41.2±1.5

33.0±1.9

MWF HS (8)

408±35

4.1±0.3

3.3±0.4

36.6±1.3

32.4±1.6

Wis LS (6)

355±41

4.8±0.4

3.8±0.5

43.6±1.9

43.7±2.4

18.9±1.3

10.2±1.1

Wis HS (9)

400±52

4.5±0.5

3.8±0.6

32.6±2.3

35.7±3.0

18.1±1.3

12.6±1.1

*P<0.01 vs control period.
**P<0.01 vs LS. Jprox’ is Jprox adjusted for single nephron GFR by ANCOVA to obtain the "primary" effect of SGLT2 blockade on the tubule.
The Molecular Mechanism of Cellular Attachment for an Archaeal Virus
Authors: Lawrence C. Martin , Hartman Ross , Eilers Brian J. , Young Mark J. 
Published: April 2020

Sulfolobus turreted icosahedral virus (STIV) is a model archaeal virus with a pseudo‐T=31 icosahedral virion with a mass of ~64 mega‐Daltons. Although STIV employs pyramidal lysis structures to exit the host, knowledge of the viral entry process is lacking. We therefore initiated crystallographic and cryo‐electron tomographic (CET) studies on STIV attachment and entry. Cryoelectron micrographs showed virion attachment to pili‐like structures emanating from the Sulfolobus host. Tomographic reconstruction and sub‐tomogram averaging revealed pili recognition by the STIV C381 turret protein. Specifically, the triple jelly roll structure of C381 determined by X‐ray crystallography shows that pilus recognition is mediated by conserved surface residues in the second and third domains. In addition, the STIV petal protein (C557), when present, occludes the pili binding site, suggesting that it functions as a maturation protein. Combined, these results demonstrate a role for the namesake STIV turrets in initial cellular attachment and provide the first molecular model for viral attachment in the archaeal domain of life. The work also nicely illustrates the synergistic power of hybrid structural studies utilizing cryo‐electron tomography, single particle analysis and crystallography to model cellular structures at the molecular level.Support or Funding InformationThis work was supported by the National Science Foundation, grants DEB‐1342876 to M.J.Y. and MCB‐1413534 to C.M.L.Tomographic structure of the STIV pilus interaction. (A–J)2.25 nm thick sections at 10 nm spacings through the tomogram. (K) Subvolume averages are shown. The virus/pilus interaction is at the viral turret.(L) The turret highlighted in K rotated 90°, looking into a pilus cross section. C381 is light, medium and dark purple showing the 1st, 2nd and 3rd domains. M)Pilus recognition is mediated by the 2nd and 3rd domains. N)Surface exposed, strictly conserved residues mediate C381/pili recognition.Figure 1
An interbacterial toxin inhibits target cell growth by synthesizing (p)ppApp
Authors: Whitney John , Ahmad Shehryar , Wang Boyuan , Laub Michael 
Published: April 2020

Bacteria have evolved sophisticated mechanisms to inhibit the growth of competitors. One such mechanism involves type VI secretion systems, which can be used by bacteria to directly inject antibacterial toxins into neighbouring cells. Many of these toxins target cell envelope integrity, but the full range of growth inhibitory mechanisms remains to be determined. Here, we discover a novel type VI secretion effector, Tas1, in the opportunistic pathogen Pseudomonas aeruginosa. A crystal structure of Tas1 reveals similarity to enzymes that synthesize (p)ppGpp, a broadly conserved signaling molecule in bacteria that modulates cell growth rate, particularly in response to nutritional stress. Strikingly, however, we find that Tas1 does not synthesize (p)ppGpp, and instead pyrophosphorylates adenosine nucleotides to produce (p)ppApp at rates of nearly 180,000 per minute. Consequently, delivery of Tas1 into competitor cells drives the rapid accumulation of (p)ppApp, depletion of ATP, and widespread dysregulation of essential metabolic pathways, resulting in target cell death. Collectively, our findings reveal a new mechanism for interbacterial antagonism and demonstrate, for the first time, a physiological role for the metabolite (p)ppApp in bacteria.Support or Funding InformationCanadian Institutes of Health Research, David Braley Centre for Antibiotic Discovery, National Institutes of Health, Howard Hughes Medical InstituteStructure of the (p)ppApp synthetase toxin Tas1 in complex with its cognate immunity protein, Tis1.Figure 1Tas1 is a pyrophosphokinase that is specific for canonical 5′‐adenosine nucleotides.Figure 2
Three Self‐resistance Modifications Discovered in Nucleoside Antibiotic Muraymycin
Authors: Cui Zheng , Van Lanen Steven G. 
Published: April 2020

BackgroundMuraymycins, discovered by Wyeth Research in 2002, are lipopeptidyl nucleoside antibiotics that inhibit the enzyme bacterial translocase I involved in peptidoglycan cell wall. Muraymycin exhibits good activities against gram‐positive bacteria and excellent activity against a permeabilized E. coli. However, the self‐resistance mechanism during muraymycin biosynthesis has not been elucidated.ObjectivesOur long‐term research goal is to delineate the biosynthetic pathway of muraymycin in order to develop more active analogues through chemo‐enzymatic synthesis and mutasynthesis. Our current goal is to study the self‐resistance mechanism during muraymycin biosynthesis to assist structure–activity relationship (SAR) study of muraymycins.MethodsTo interrogate the self‐resistance mechanism during muraymycin biosynthesis, we analyzed its biosynthetic gene cluster. Two genes, mur28 and mur29 that potentially catalyzed the resistant modifications were cloned and expressed. We also cultured muraymycin‐producing strain to isolate resistant modified muraymycins. LC‐MS and NMR analysis was utilized to determine the resistant modified products.ResultsMur28 and Mur29 were functionally assigned in vitro as an ATP‐dependent phosphotransferase and an ATP‐dependent nucleotidyltransferase, both modifying the 3″‐OH of muraymycins. Interestingly, from single‐substrate kinetic analyses, we discovered that Mur28 preferentially phosphorylates a hypothetical biosynthetic precursor of muraymycin: a GlyU‐ADR disaccharide, while Mur29 preferentially adenylates muraymycin. Besides the two resistant modification products, a new muraymycin acetylaed at the 5″‐amine of the ADR moiety was isolated from muraymycin‐producing strain. The adenylated, phosphorylated and acetylated products have significantly reduced MraY inhibitory activities and reduced antibacterial activities, compared with the respective unmodified muraymycins.ConclusionPhosphorylation, nucleotidylation and acetylation, are three types of resistant modifications that are often found as mechanisms of resistance to antibiotics, most notably aminoglycoside antibiotics. Here, we first discovered all these three types of resistant modifications in the nucleoside antibiotic muraymycin. Among these, Mur28 serves as complementary self‐resistance mechanism, with a distinct temporal order during muraymycin biosynthesis.Support or Funding InformationThis work was supported by the National Institutes of Health (grant AI087849).TOCFigure 1
Oxidative Stress Induced by Loss of Superoxide Dismutases Leads to Activation of No‐Go Decay
Authors: Cianflone Emily , Champine Madison , Lobb Amber , Segal Scott P. 
Published: April 2020

Reactive oxygen species (ROS) are known to cause oxidative damage in the cell and have been connected to many neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and cancer. Superoxide dismutases (SODs) are a group of enzymes that act to prevent oxidative damage from ROS by converting O2− to H2O2. In Saccharomyces cerevisiae, there are two SOD proteins that are expressed, each of which is conserved in humans. Sod1p is a cytoplasmic Cu/Zn coordinated enzyme, whereas Sod2p coordinates Mn2+ and localizes to mitochondria. Although there is significant data showing that loss of SOD proteins allows for high levels of intracellular oxidation, it is unknown what effects that would have on the translating pool of mRNA. Current work has revealed that strains lacking Sod1p have a moderate decrease in general translation and an increase in P‐body assembly. Furthermore, this reduction in translation is likely due to the formation of 8‐oxo(G) bases in mRNA, which can cause ribosome stalls leading to the subsequent activation of the No‐Go quality control pathway. No‐Go decay is mediated by the proteins Dom34p and Hbs1p, which act together to remove stalled ribosomes and promote endonucleolytic cleavage of the mRNA at the stall site. The 3′ fragment of mRNA is then localized to P‐bodies to be degraded 5′ to 3′ by Xrn1p, whereas the 5′ fragment is degraded by the cytoplasmic exosome.Sod2p performs a similar role to Sod1p, as it also converts O2− to H2O2, and plays an important role in preventing the formation of strong oxidant peroxynitrate (ONOO−). Given that it localizes to mitochondria, a loss of Sod2p would result in higher levels of mitochondrially derived ROS. To determine the effect of mitochondrially derived ROS on the translating pool of mRNA, both general translation and P‐body assembly will be analyzed in strains lacking Sod2p. If general translation is reduced and P‐body assembly is increased, then it will be ascertained whether No‐Go Decay is being upregulated in the absence of Sod2p. To perform this analysis, double mutant strains lack both Sod2p and No‐Go Decay will be created and further analyzed for general translational control and P‐body assembly.
From mathematical model towards educational simulation game of hemodynamics of cardiovascular system
Authors: Kulhanek Tomas , Kofránek Jiøí , Mateják Marek , Ježek Filip , Šilar Jan , Mládek Arnošt , Feberová Jitka , Feber Martin , Zazay Awista 
Published: April 2020

Recently we have created a new open‐source technology called BodyLight.js which combines the current standard for web‐based applications including Web‐Assembly for fast computation of mathematical models, web components for building independent transferable objects, and WebGL for involving 3D graphic
[1,
2].We have published methodology and implementation of several models of the cardiovascular system
[3].We have been creating graphical components in 2D and recently in 3D which can be used as animations in simulation application.There are numerous steps involved when going from an idea to a finished project. In this contribution we describe the workflow going from concept to mathematical model and computer graphics to an educational simulation application. This workflow is presented by building a simulation game of hemodynamics of the cardiovascular system.Each step of the workflow can be executed by different domain expert. Physiologist designs concept, mathematician writes and implements mathematical models and executable model simulation programs, graphical designer produces graphical objects based on design concepts which can be animated in simulation programs, and software engineer maintains the system. However, all these professionals need to be able to understand each other and work together.Physiologists must be able to grasp the physiological significance and to tell mathematician how to formalize the problem. Mathematicians and software engineers need to understand physiology in order to produce plausible and verifiable model simulation application. Computer graphics designers must be skilled in programming as they need to produce animated objects that can be used in simulation applications. This connection of expertise is crucial, and was already proposed e.g. by N. Wiener in his works about Cybernetics
[4].We demonstrate that such creative connection of individuals with combined and shared expertise can produce high quality educational materials.Support or Funding InformationMPO TRIO FV20628, MPO TRIO FV30195Collaborative workflow designing simulator of pressure‐volume loop cycle of hemodynamics model using Bodylight.js software tools.Figure 1
SPARC_A DNA‐based optical nanosensor for in vivo imaging of acetylcholine in the peripheral nervous system
Authors: Clark Heather , Monaghan James , Yang Hongrong , Xia Junfei , Mu Michelle , Lovely Alexander , Micovic Nicholas 
Published: April 2020

The study of neurotransmitter signaling helps to understand fundamental neuronal circuits and develop strategies against neurodegenerative diseases. Acetylcholine (ACh) plays a pivotal role in modulating neuron functions. Monitoring its physiological level in real‐time and probing its biological distribution is of crucial importance. However, the current techniques are subject to temporal and spatial limitations which impede their further in vivo applications. Herein we report the development of a ACh nanosensor by using DNA as a scaffold, acetylcholinesterase as a recognition component, pH‐sensitive fluorophores as signal generator, and α‐bungarotoxin as a targeting ligand. The nanosensor was delivered to the submandibular ganglion in living mice by microinjection for in vivo imaging of endogenous ACh release. The ACh nanosensor selectively binds to acetylcholine receptors on the post‐synaptic neurons, and display a sensitive response to physiological ACh range from 0.228 μM to 358 μM in ex vivo calibration. The ACh nanosensors also respond to endogenous ACh release triggered by electrical stimulation in a reversible and dose‐dependent manner. We also found that the treatment of cholinergic inhibitor, Vesamicol, significant suppresses the response of the ACh nanosensor. This work provides a tool for in vivo imaging of ACh dynamics with unprecedented capabilities to enhance the spatial and temporal resolution of detection. We envision such a sensor platform could be applied to imaging other neurotransmitters in mammalian system as well as extended to other organ systems in the peripheral nervous systemSupport or Funding InformationNIH common fund_SPARC_Project number: 1OT2OD024909‐01DNA‐based acetylcholine (ACh) nanosensors detect the ACh in the submandibular ganglion (SMG) of living mice. (A) ACh sensors were microinjected into the SMG of a living mouse. With the targeting ability of bungarotoxin, the ACh nanosensor can immobilize in the synaptic cleft of the mouse. (B) The mechanism of ACh nanosensors. (D) ΔF/F from pHAb channel in response to electrical stimulation (indicated by red arrow).Figure 1
Exercise‐induced Increase in Hexokinase II‐mitochondria Association Reduces Cardiac Ischemia‐Reperfusion Injury in Rats
Authors: Mishra Jyotsna , Kwok Wai-Meng , Fitts Robert H. , Camara Amadou K.S. 
Published: April 2020

IntroductionExercise‐training has been shown to modulate signaling pathways that contribute to improved mitochondrial function in the heart. AKT, a serine/threonine protein kinase pathway is a critical regulator of a variety of cellular functions and its activation is implicated in cardioprotection from ischemia‐reperfusion (I/R) injury. Importantly, the AKT pathway has been shown to be upregulated in exercise. However, the interplay between AKT signaling, mitochondrial function and cardio‐protection in exercise remains to be well elucidated.AIMHerein, we investigated the role of exercise‐induced AKT/Hexokinase II (HKII)‐signaling as a potential mechanism in preserving mitochondrial function and thereby, contribute to cardioprotection against I/R injury.MethodsIsolated hearts from rats, randomly assigned to either sedentary (SED) group or 6–8 weeks treadmill trained (TRN) group, were subjected to 30 min global ischemia and 5 min reperfusion. Mitochondria were isolated immediately after reperfusion and the effects of exercise on cardiac mitochondrial bioenergetics, including changes in O2 consumption rate, mitochondrial membrane potential (ΔΨm), and mitochondrial calcium retention capacity (CRC) was examined. Western blot was performed to quantify the total AKT, p‐AKT and p‐HKII. In addition, we checked the subcellular distributions of HKII and examined the regulation of apoptotic markers at the mitochondrial level. In some hearts, cardiac functional variables and infarct size were also assessed after 120 min reperfusion in SED and TRN rats.ResultsWe found that exercise increased the phosphorylation of AKT in TRN rat hearts, which was associated, concomitantly, with increased phosphorylation of HKII and increased translocation to mitochondria following IR. TRN rats also showed a decreased expression of Bax and DRP1 in mitochondrial fraction and inhibition of caspase‐3 activation. Furthermore, exercise preserved the mitochondrial bioenergetics with significantly higher respiratory control index and more normalized ΔΨm compared to SED rats (see schematic). CRC was greater in TRN rats compared to SED rats (226.6 ± 13.3 nmol /mg protein vs 173.3 ± 13.3 nmol /mg protein). These improvements in mitochondrial function in TRN rats correlated with improved cardiac function during reperfusion.ConclusionThe results indicate that AKT‐mediated HKII‐mitochondrial interaction due to exercise protects mitochondria by inhibiting mitochondrial apoptotic cascades and likely contributes to the increased cardioprotection against IR injury.Support or Funding InformationThis work was supported by NIH grant R01 HL131673‐01A1 to AKSC and WMKSchematic diagram for exercise‐induced activation of AKT‐HKII signaling pathway during IR injury (A). Time course of the mitochondrial O2 consumption, membrane potential (B) and calcium retention capacity (C) in SED and TRN rats after IR stress.Figure 1