Impact of Tilapia hepcidin 2-3 dietary supplementation on the gut microbiota profile and immunomodulation in the grouper (Epinephelus lanceolatus)

Hepcidin regulates iron homeostasis and host-defense mechanisms, while the hepcidin-like protein, Tilapia hepcidin (TH)2-3, functions as an antimicrobial peptide (AMP). Since AMP dietary supplements may be used as alternatives to antibiotics in livestock, we tested the effects of recombinant (r)TH2-3 as a dietary supplement in grouper aquaculture. rTH2-3 was produced by a Pichia pastoris expression system and exhibited thermostability and broad-spectrum antimicrobial activity. The feed conversion ratio and feed efficiency were determined in Epinephelus lanceolatus (grouper) fed with rTH2-3-supplemented diet for 28 days. In addition, grouper showed enhanced superoxide dismutase (SOD) activity after rTH2-3 feeding compared to regular-diet-fed fish. Gut microbiota analysis revealed that microbial diversity was enhanced by feeding grouper with 1% rTH2-3. After challenging grouper with Vibrio alginolyticus, differential regulation of immune-related genes in the liver and spleen was observed between the TH2-3 and regular-diet groups, including for genes associated with antimicrobial and pro-inflammatory functions, complement components, and major histocompatibility complex (Mhc). These findings suggest that overall immunity was improved. Thus, our results suggest long-term supplementation with rTH2-3 may be beneficial for aquacultured grouper. The beneficial effects of the supplement are likely based on changes in the commensal microbial community as well as immunomodulation.

Enantioselective Synthesis of 8-Hydroxyquinoline Derivative, Q134 as a Hypoxic Adaptation Inducing Agent

Hypoxia is a common feature of neurodegenerative diseases, including Alzheimer’s disease that may be responsible for disease pathogenesis and progression. Therefore, the hypoxia-inducible factor (HIF)1 system, responsible for hypoxic adaptation, is a potential therapeutic target to combat these diseases by activators of cytoprotective protein induction. We have selected a candidate molecule from our cytoprotective hydroxyquinoline library and developed a novel enantioselective synthesis for the production of its enantiomers. The use of quinidine or quinine as a catalyst enabled the preparation of enantiomer-pure products. We have utilized in vitro assays to evaluate cytoprotective activity, a fluorescence-activated cell sorting (FACS) based assay measuring mitochondrial membrane potential changes, and gene and protein expression analysis. Our data showed that the enantiomers of Q134 showed potent and similar activity in all tested assays. We have concluded that the enantiomers exert their cytoprotective activity via the HIF1 system through HIF1A protein stabilization.

mTOR hyperactivity mediates lysosomal dysfunction in Gaucher's disease iPSC-neuronal cells

Bi-allelic GBA1 mutations cause Gaucher's disease (GD), the most common lysosomal storage disorder. Neuronopathic manifestations in GD include neurodegeneration, which can be severe and rapidly progressive. GBA1 mutations are also the most frequent genetic risk factors for Parkinson's disease. Dysfunction of the autophagy-lysosomal pathway represents a key pathogenic event in GBA1-associated neurodegeneration. Using an induced pluripotent stem cell (iPSC) model of GD, we previously demonstrated that lysosomal alterations in GD neurons are linked to dysfunction of the transcription factor EB (TFEB). TFEB controls the coordinated expression of autophagy and lysosomal genes and is negatively regulated by the mammalian target of rapamycin complex 1 (mTORC1). To further investigate the mechanism of autophagy-lysosomal pathway dysfunction in neuronopathic GD, we examined mTORC1 kinase activity in GD iPSC neuronal progenitors and differentiated neurons. We found that mTORC1 is hyperactive in GD cells as evidenced by increased phosphorylation of its downstream protein substrates. We also found that pharmacological inhibition of glucosylceramide synthase enzyme reversed mTORC1 hyperactivation, suggesting that increased mTORC1 activity is mediated by the abnormal accumulation of glycosphingolipids in the mutant cells. Treatment with the mTOR inhibitor Torin1 upregulated lysosomal biogenesis and enhanced autophagic clearance in GD neurons, confirming that lysosomal dysfunction is mediated by mTOR hyperactivation. Further analysis demonstrated that increased TFEB phosphorylation by mTORC1 results in decreased TFEB stability in GD cells. Our study uncovers a new mechanism contributing to autophagy-lysosomal pathway dysfunction in GD, and identifies the mTOR complex as a potential therapeutic target for treatment of GBA1-associated neurodegeneration.

AKR1C3 Promotes AR-V7 Protein Stabilization and Confers Resistance to AR-Targeted Therapies in Advanced Prostate Cancer

The mechanisms resulting in resistance to next-generation antiandrogens in castration-resistant prostate cancer are incompletely understood. Numerous studies have determined that constitutively active androgen receptor (AR) signaling or full-length AR bypass mechanisms may contribute to the resistance. Previous studies established that AKR1C3 and AR-V7 play important roles in enzalutamide and abiraterone resistance. In the present study, we found that AKR1C3 increases AR-V7 expression in resistant prostate cancer cells through enhancing protein stability via activation of the ubiquitin-mediated proteasome pathway. AKR1C3 reprograms AR signaling in enzalutamide-resistant prostate cancer cells. In addition, bioinformatical analysis of indomethacin-treated resistant cells revealed that indomethacin significantly activates the unfolded protein response, p53, and apoptosis pathways, and suppresses cell-cycle, Myc, and AR/ARV7 pathways. Targeting AKR1C3 with indomethacin significantly decreases AR/AR-V7 protein expression in vitro and in vivo through activation of the ubiquitin-mediated proteasome pathway. Our results suggest that the AKR1C3/AR-V7 complex collaboratively confers resistance to AR-targeted therapies in advanced prostate cancer.

Micropatterned nanolayers immobilized with nerve growth factor for neurite formation of PC12 cells

BACKGROUND

Nerve regeneration is important for the treatment of degenerative diseases and neurons injured by accidents. Nerve growth factor (NGF) has been previously conjugated to materials for promotion of neurogenesis.

MATERIALS AND METHODS

Photoreactive gelatin was prepared by chemical coupling of gelatin with azidobenzoic acid (P-gel), and then NGF was immobilized on substrates in the presence or absence of micropatterned photomasks. UV irradiation induced crosslinking reactions of P-gel with itself, NGF, and the plate for immobilization.

RESULTS

By adjustment of the P-gel concentration, the nanometer-order height of micropatterns was controlled. NGF was quantitatively immobilized with increasing amounts of P-gel. Immobilized NGF induced neurite outgrowth of PC12 cells, a cell line derived from a pheochromocytoma of the rat adrenal medulla, at the same level as soluble NGF. The immobilized NGF showed higher thermal stability than the soluble NGF and was repeatedly used without loss of biological activity. The 3D structure (height of the formed micropattern) regulated the behavior of neurite guidance. As a result, the orientation of neurites was regulated by the stripe pattern width.

CONCLUSION

The micropattern-immobilized NGF nanolayer biochemically and topologically regulated neurite formation.

Diverse Structural Conversion and Aggregation Pathways of Alzheimer's Amyloid-β (1-40)

Complex amyloid aggregation of amyloid-β (1-40) (Aβ_1-40) in terms of monomer structures has not been fully understood. Herein, we report the microscopic mechanism and pathways of Aβ_1-40 aggregation with macroscopic viewpoints through tuning its initial structure and solubility. Partial helical structures of Aβ_1-40 induced by low solvent polarity accelerated cytotoxic Aβ_1-40 amyloid fibrillation, while predominantly helical folds did not aggregate. Changes in the solvent polarity caused a rapid formation of β-structure-rich protofibrils or oligomers via aggregation-prone helical structures. Modulation of the pH and salt concentration transformed oligomers to protofibrils, which proceeded to amyloid formation. We reveal diverse molecular mechanisms underlying Aβ_1-40 aggregation with conceptual energy diagrams and propose that aggregation-prone partial helical structures are key to inducing amyloidogenesis. We demonstrate that context-dependent protein aggregation is comprehensively understood using the macroscopic phase diagram, which provides general insights into differentiation of amyloid formation and phase separation from unfolded and folded structures.

JTZ-951 (enarodustat), a hypoxia-inducibe factor prolyl hydroxylase inhibitor, stabilizes HIF-α protein and induces erythropoiesis without effects on the function of vascular endothelial growth factor

JTZ-951 (enarodustat) is an oral hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor. JTZ-951 has inhibitory activities on human HIF-prolyl hydroxylase 1-3, but not on various receptors or enzymes. In Hep3B cells, JTZ-951 increased HIF-1α and HIF-2α protein levels, erythropoietin (EPO) mRNA levels, and EPO production. In normal rats, after a single oral dose of JTZ-951, the hepatic and renal EPO mRNA levels and plasma EPO concentrations were also increased. In 5/6-nephrectomized rats, repeated oral doses of JTZ-951 once daily or intermittent dosing showed the erythropoiesis stimulating effect. The administration of JTZ-951 at a high dose increased plasma vascular endothelial growth factor (VEGF) levels; however, retinal VEGF mRNA levels and the retinal vascular permeability were not changed. Finally, we evaluated the effect of JTZ-951 in a colorectal cancer cell-inoculated mouse model. Although JTZ-951 at a high dose increased the plasma VEGF, it had no effect on tumor growth. In summary, JTZ-951 induces erythropoiesis without affecting VEGF function. Therefore, it is expected that JTZ-951 will be a new oral candidate that increases and maintains hemoglobin concentrations in renal anemia patients.

An E3 ubiquitin ligase from Nicotiana benthamiana targets the replicase of Bamboo mosaic virus and restricts its replication

One up-regulated host gene identified previously was found involved in the infection process of Bamboo mosaic virus (BaMV), a single-stranded positive-sense RNA virus. The full length cDNA of this gene was cloned by 5' and 3'-rapid amplification of cDNA ends and found to encode a polypeptide containing a conserved really interesting new gene (RING) domain and a transmembrane domain. The gene might function as an ubiquitin E3 ligase. We designated this protein in Nicotiana benthamiana as ubiquitin E3 ligase containing RING domain 1 (NbUbE3R1). Further characterization by using Tobacco rattle virus-based virus-induced gene silencing (loss-of-function) revealed that increased BaMV accumulation was in both knockdown plants and protoplasts. The gene might have a defensive role in the replication step of BaMV infection. To further inspect the functional role of NbUbE3R1 in BaMV accumulation, NbUbE3R1 was expressed in N. benthamiana plants. The wild-type NbUbE3R1-orange fluorescent protein (NbUbE3R1-OFP), NbUbE3R1/△TM-OFP (removal of the transmembrane domain) and NbUbE3R1/mRING-OFP (mutation at the RING domain, the E2 interaction site) were transiently expressed in plants. NbUbE3R1 and its derivatives all functioned in restricting the accumulation of BaMV. The common feature of these constructs was the intact substrate-interacting domain. Yeast two-hybrid and co-immunoprecipitation experiments used to determine the possible viral-encoded substrate of NbUbE3R1 revealed the replicase of BaMV as the possible substrate. In conclusion, we identified an up-regulated gene, NbUbE3R1 that plays a role in BaMV replication.

The RCC1 family protein SAB1 negatively regulates ABI5 through multidimensional mechanisms during postgermination in Arabidopsis

Abscisic acid-insensitive 5 (ABI5) is an essential and conserved plant basic leucine zipper transcription factor whose level controls seed germination and postgerminative development. It has been demonstrated that activity of ABI5 is transcriptionally and post-translationally regulated. However, transcriptional regulation of ABI5 is not fully understood. Here, we identified SAB1 (Sensitive to ABA 1) as a novel negative regulator of ABI5 that simultaneously regulates its stability, promoter binding activity and histone methylation-mediated gene silencing of ABI5. SAB1 encodes a Regulator of Chromatin Condensation 1 (RCC1) family protein and is expressed in an opposite pattern to that of ABI5 during early seedling growth in response to abscisic acid (ABA). SAB1 mutation results in enhanced ABA sensitivity and acts upstream of ABI5. SAB1 physically interacts with ABI5 at phosphoamino acid Ser-145, and reduces the phosphorylation of ABI5 and the protein stability. SAB1 reduces ABI5 binding activity to its own promoter, leading to reduced transcriptional level of ABI5. SAB1 inactivates ABI5 transcription by increasing the level of histone H3K27me2 in the ABI5 promoter. Our findings have identified SAB1 as a crucial new component of ABA signaling which modulates early development of plant by precisely controlling ABI5 activity through multiple mechanisms.

Hypoxia mimicking hydrogels to regulate the fate of transplanted stem cells

Controlling the phenotype of transplanted stem cells is integral to ensuring their therapeutic efficacy. Hypoxia is a known regulator of stem cell fate, the effects of which can be mimicked using hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitors such as dimethyloxalylglycine (DMOG). By releasing DMOG from mesenchymal stem cell (MSC) laden alginate hydrogels, it is possible to stabilize HIF-1α and enhance its nuclear localization. This correlated with enhanced chondrogenesis and a reduction in the expression of markers associated with chondrocyte hypertrophy, as well as increased SMAD 2/3 nuclear localization in the encapsulated MSCs. In vivo, DMOG delivery significantly reduced mineralisation of the proteoglycan-rich cartilaginous tissue generated by MSCs within alginate hydrogels loaded with TGF-β3 and BMP-2. Together these findings point to the potential of hypoxia mimicking hydrogels to control the fate of stem cells following their implantation into the body. STATEMENT OF SIGNIFICANCE: There are relatively few examples where in vivo delivery of adult stem cells has demonstrated a true therapeutic benefit. This may be attributed, at least in part, to a failure to control the fate of transplanted stem cells in vivo. In this paper we describe the development of hydrogels that mimic the effects of hypoxia on encapsulated stem cells. In vitro, these hydrogels enhance chondrogenesis of MSCs and suppress markers associated with chondrocyte hypertrophy. In an in vivo environment that otherwise supports progression along an endochondral pathway, we show that these hydrogels will instead direct mesenchymal stem cells (MSCs) to produce a more stable, cartilage-like tissue. In addition, we explore potential molecular mechanisms responsible for these phenotypic changes in MSCs.

Comparison of genotoxic versus nongenotoxic stabilization of p53 provides insight into parallel stress-responsive transcriptional networks

The tumor suppressor protein p53 is activated in response to diverse intrinsic and extrinsic cellular stresses and controls a broad cell-protective gene network. Whether p53:DNA binding and subsequent transcriptional activation differs downstream of these diverse intrinsic and extrinsic activators is controversial. Using primary human fibroblasts, we assessed the genome-wide profile of p53 binding, chromatin structure, and transcriptional dynamics after either genotoxic or nongenotoxic activation of p53. Activation of p53 by treatment with either etoposide or the small-molecule MDM2 inhibitor nutlin 3A yields strikingly similar genome-wide binding of p53 and concomitant changes to local chromatin modifications and structure. DNA damage, but not p53 activation per se, leads to increased expression of genes in an inflammatory cytokine pathway. The NF-κB pathway inhibitor Bay 11-7082 abrogates etoposide-mediated activation of the inflammation gene signature but does not affect expression of canonical p53 target genes. Our data demonstrate that differential activation of p53 within the same cell type leads to highly similar genome-wide binding, chromatin dynamics, and gene expression dynamics and that DNA damage-mediated signaling through NF-κB likely controls the observed pro-inflammatory cytokine gene expression pattern.

Novel Flavivirus Antiviral That Targets the Host Nuclear Transport Importin α/β1 Heterodimer

Dengue virus (DENV) threatens almost 70% of the world’s population, with no effective vaccine or therapeutic currently available. A key contributor to infection is nuclear localisation in the infected cell of DENV nonstructural protein 5 (NS5) through the action of the host importin (IMP) α/β1 proteins. Here, we used a range of microscopic, virological and biochemical/biophysical approaches to show for the first time that the small molecule GW5074 has anti-DENV action through its novel ability to inhibit NS5–IMPα/β1 interaction in vitro as well as NS5 nuclear localisation in infected cells. Strikingly, GW5074 not only inhibits IMPα binding to IMPβ1, but can dissociate preformed IMPα/β1 heterodimer, through targeting the IMPα armadillo (ARM) repeat domain to impact IMPα thermal stability and α-helicity, as shown using analytical ultracentrifugation, thermostability analysis and circular dichroism measurements. Importantly, GW5074 has strong antiviral activity at low µM concentrations against not only DENV-2, but also zika virus and West Nile virus. This work highlights DENV NS5 nuclear targeting as a viable target for anti-flaviviral therapeutics.

Decreased mRNA and protein stability of W1282X limits response to modulator therapy

BACKGROUND

Cell-based studies have shown that W1282X generates a truncated protein that can be functionally augmented by modulators. However, modulator treatment of primary cells from individuals who carry two copies of W1282X generates no functional CFTR. To understand the lack of response to modulators, we investigated the effect of W1282X on CFTR RNA transcript levels.

METHODS

qRT-PCR and RNA-seq were performed on primary nasal epithelial (NE) cells of a previously studied individual who is homozygous for W1282X, her carrier parents and control individuals without nonsense variants in CFTR.

RESULTS

CFTR RNA bearing W1282X in NE cells shows a steady-state level of 4.2 ± 0.9% of wild-type (WT) CFTR RNA in the mother and 12.4 ± 1.3% in the father. NMDI14, an inhibitor of nonsense-mediated mRNA decay (NMD), restored W1282X mRNA to almost 50% of WT levels in the parental NE cells. RNA-seq of the NE cells homozygous for W1282X showed that CFTR transcript level was reduced to 1.7% of WT (p-value: 4.6e-3). Negligible truncated CFTR protein was generated by Flp-In 293 cells stably expressing the W1282X EMG even though CFTR transcript was well above levels observed in the parents and proband. Finally, we demonstrated that NMD inhibition improved the stability and response to correctors of W1282X-CFTR protein expressed in the Flp-In-293 cells.

CONCLUSION

These results show that W1282X can cause substantial degradation of CFTR mRNA that has to be addressed before efforts aimed at augmenting CFTR protein function can be effective.

Human Serum Albumin Adsorption Kinetics on Silica: Influence of Protein Solution Stability

Adsorption kinetics of human serum albumin (HSA) on silica substrates was studied using optical waveguide lightmode spectroscopy (OWLS) and quartz microbalance (QCM) techniques. Measurements were performed at pH 3.5, 5.6, and 7.4 for various bulk suspension concentrations and ionic strengths. The diffusion coefficient measurements showed that for pH 3.5 the HSA molecules are stable for NaCl concentrations from 10^-3 to 0.15 M. This allowed us to precisely determine the mass transfer rate coefficients for the OWLS and QCM cells. The experimental data were adequately interpreted in terms of a hybrid random sequential adsorption model. The OWLS maximum coverage of HSA at pH 3.5, which is equal to 1.3 mg m^-2, agrees with the QCM result and with previous results derived from streaming potential measurements. Thus, the results obtained at pH 3.5 served as reference data for the analysis of adsorption kinetics at higher pHs. In this way, it was confirmed that the adsorption kinetics of HSA molecules at pH 5.6 and 7.4 was considerably slower than at pH 3.5. This effect was attributed to aggregation of HSA solutions and interpreted in terms of a theoretical model combining the Smoluchowski aggregation theory with the convective diffusion mass transfer theory. New analytical equations were derived that can be used for the interpretation of other protein adsorption from unstable solutions.

Deciphering biased inverse agonism of cangrelor and ticagrelor at P2Y12 receptor

P2Y12 receptor (P2Y12-R) is one of the major targets for drug inhibiting platelet aggregation in the treatment/prevention of arterial thrombosis. However, the clinical use of P2Y12-R antagonists faces some limitations, such as a delayed onset of action (clopidogrel) or adverse effect profile (ticagrelor, cangrelor), justifying the development of a new generation of P2Y12-R antagonists with a better clinical benefit-risk balance. Although the recent concept of biased agonism offers the possibility to alleviate undesirable adverse effects while preserving therapeutic outcomes, it has never been explored at P2Y12-R. For the first time, using highly sensitive BRET2-based probes, we accurately delineated biased ligand efficacy at P2Y12-R in living HEK293T cells on G protein activation and downstream effectors. We demonstrated that P2Y12-R displayed constitutive Gi/o-dependent signaling that is impaired by the R122C mutation, previously associated with a bleeding disorder. More importantly, we reported the biased inverse agonist efficacy of cangrelor and ticagrelor that could underlie their clinical efficacy. Our study points out that constitutive P2Y12-R signaling is a normal feature of the receptor that might be essential for platelets to respond faster to a vessel injury. From a therapeutic standpoint, our data suggest that the beneficial advantages of antiplatelet drugs might be more related to inverse agonism at P2Y12-R than to antagonism of ADP-mediated signaling. In the future, deciphering P2Y12-R constitutive activity should allow the discovery of more selective biased P2Y12-R blockers demonstrating therapeutic advantages over classical antiplatelet drugs by improving therapeutic outcomes and concomitantly relieving undesirable adverse effects.

Analysis of Microtubule Dynamics Heterogeneity in Cell Culture

Microtubules (MTs) are dynamic components of the cytoskeleton playing an important role in a large number of cell functions. Individual MTs in living cells undergo stochastic switching between alternate states of growth, shortening and attenuated phase, a phenomenon known as tempered dynamic instability. Dynamic instability of MTs is usually analyzed by labeling MTs with +TIPs, namely, EB proteins. Tracking of +TIP trajectories allows analyzing MT growth in cells with a different density of MTs. Numerous labs now use +TIP to track growing MTs in a variety of cell cultures. However, heterogeneity of MT dynamics is usually underestimated, and rather small sampling for the description of dynamic instability parameters is often used. The strategy described in this chapter is the method for repetitive quantitative analysis of MT growth rate within the same cell that allows minimization of the variation in MT dynamics measurement. We show that variability in MT dynamics within a cell when using repeated measurements is significantly less than between different cells in the same chamber. This approach allows better estimation of the heterogeneity of cells' responses to different treatments. To compare the effects of different MT inhibitors, the protocol using normalized values for MT dynamics and repetitive measurements for each cell is employed. This chapter provides detailed methods for analysis of MT dynamics in tissue cultures. We describe protocols for imaging MT dynamics by fluorescent microscopy, contrast enhancement technique, and MT dynamics analysis using triple color-coded display based on sequential subtraction analysis.

A cell separation checkpoint that enforces the proper order of late cytokinetic events

Eukaryotic cell division requires dependency relationships in which late processes commence only after early ones are appropriately completed. We have discovered a system that blocks late events of cytokinesis until early ones are successfully accomplished. In budding yeast, cytokinetic actomyosin ring contraction and membrane ingression are coupled with deposition of an extracellular septum that is selectively degraded in its primary septum immediately after its completion by secreted enzymes. We find this secretion event is linked to septum completion and forestalled when the process is slowed. Delay of septum degradation requires Fir1, an intrinsically disordered protein localized to the cytokinesis site that is degraded upon septum completion but stabilized when septation is aberrant. Fir1 protects cytokinesis in part by inhibiting a separation-specific exocytosis function of the NDR/LATS kinase Cbk1, a key component of "hippo" signaling that induces mother-daughter separation. We term this system enforcement of cytokinesis order, a checkpoint ensuring proper temporal sequence of mechanistically incompatible processes of cytokinesis.

Synergistic activity of BET inhibitor MK-8628 and PLK inhibitor Volasertib in preclinical models of medulloblastoma

Medulloblastoma is the most prevalent central nervous system tumor in children. Targeted treatment approaches for patients with high-risk medulloblastoma are needed as current treatment regimens are not curative in many cases and cause significant therapy-related morbidity. Medulloblastoma harboring MYC amplification have the most aggressive clinical course and worst outcome. Targeting the BET protein BRD4 has significant anti-tumor effects in preclinical models of MYC-amplified medulloblastoma, however, in most cases these are not curative. We here assessed the therapeutic efficacy of the orally bioavailable BRD4 inhibitor, MK-8628, in preclinical models of medulloblastoma. MK-8628 showed therapeutic efficacy against in vitro and in vivo models of MYC-amplified medulloblastoma by inducing apoptotic cell death and cell cycle arrest. Gene expression analysis of cells treated with MK-8628 showed that anti-tumor effects were accompanied by significant repression of MYC transcription as well as disruption of MYC-regulated transcriptional programs. Additionally, we found that targeting of MYC protein stability through pharmacological PLK1 inhibition showed synergistic anti-medulloblastoma effects when combined with MK-8628 treatment. Thus, MK-8628 is effective against preclinical high-risk medulloblastoma models and its effects can be enhanced through simultaneous targeting of PLK1.

Transcriptional repression of IKKβ by p53 in arsenite-induced GADD45α accumulation and apoptosis

Our previous studies revealed that GADD45α is a liable protein, which undergoes MDM2-dependent constitutive ubiquitination and degradation in resting HepG2 hepatoma cells. Arsenite exposure induces ribosomal stress responses mediated by the ribosomal protein S7, which can block MDM2 activity and result in GADD45α accumulation and cell apoptosis. In the present study, we found that one of the catalytic subunits of IκB kinase (IKK), IKKβ, exerted a novel IKKα- and NF-κB-independent function in stabilizing MDM2 and therefore contributed to ubiquitination-dependent degradation of GADD45α in resting HepG2 cells. Arsenite stimulation induced transactivation of p53, which formed a complex with its downstream target, Ets-1, and then synergistically repressed IKKβ transcription, reduced MDM2 stability, and ultimately removed the inhibitory effect of MDM2 on GADD45α induction. In addition, DAPK1 functioned as an upstream protein kinase triggering p53/Ets-1-dependent IKKβ and MDM2 reduction and GADD45α accumulation, thus promoting apoptosis in HepG2 cells. Subsequent studies further revealed that the activation of the DAPK1/p53/Ets-1/IKKβ/MDM2/GADD45α cascade was a common signaling event in mediating apoptosis of diverse cancer cells induced by arsenite and other tumor therapeutic agents. Therefore, we conclude that data in the current study have revealed a novel role for IKKβ in negatively regulating GADD45α protein stability and the contribution of p53-dependent IKKβ reduction to mediating cancer cell apoptosis.

Detection of Hypoxia-Regulated MicroRNAs in Blood as Potential Biomarkers of HIF Stabilizer Molidustat

BACKGROUND

The recent development of drugs that stabilize HIFalpha, called HIF stabilizers, offers a new strategy for treating anemia. Although these drugs are still in clinical trials, misuse for doping has already begun. Identifying the biomarkers of HIF stabilizers would therefore help in detecting this drug misuse by athletes.

OBJECTIVE

Our aim was twofold: to determine whether hypoxamiRs, the microRNAs associated with the cellular response to hypoxia, are potential biomarkers of HIF stabilizers in blood and whether the response to treatment with an HIF stabilizer differs from the response to a hypoxic environment.

METHOD

Rats were treated for 6 days with either a placebo or 2mg/kg of Molidustat, an HIF stabilizer, or they were put under hypoxia (10% oxygen) for the same length of time. Plasma samples were analyzed before, during and 48 hours after the treatments.

RESULTS

EPO concentration increased significantly in plasma during hypoxia and Molidustat treatment and showed a negative retro-control 2 days after the end of the treatments. On the contrary, circulating levels of VEGF were not modified. Among the hypoxamiRs tested, miR-130a and miR-21 were significantly increased during Molidustat treatment and miR-21 was still increased 48 hours after treatment end.

CONCLUSION

Although using these microRNAs as biomarkers seems unlikely due to other possible factors of regulation, this study provides the first identification of a specific effect of HIF stabilizers on microRNAs. Further investigations are needed to better understand the possible consequences of such regulation.

The wheat TdRL1 is the functional homolog of the rice RSS1 and promotes plant salt stress tolerance

Rice rss1 complementation assays show that wheat TdRL1 and RSS1 are true functional homologs. TdRL1 over-expression in Arabidopsis conferred salt stress tolerance and alleviated ROS accumulation. Plants have developed highly flexible adaptive responses to their ever-changing environment, which are often mediated by intrinsically disordered proteins (IDP). RICE SALT SENSITIVE 1 and Triticum durum RSS1-Like 1 protein (TdRL1) are both IDPs involved in abiotic stress responses, and possess conserved D and DEN-Boxes known to be required for post-translational degradation by the APC/C^cdc20 cyclosome. To further understand their function, we performed a computational analysis to compare RSS1 and TdRL1 co-expression networks revealing common gene ontologies, among which those related to cell cycle progression and regulation of microtubule (MT) networks were over-represented. When over-expressed in Arabidopsis, TdRL1::GFP was present in dividing cells and more visible in cortical and endodermal cells of the Root Apical Meristem (RAM). Incubation with the proteasome inhibitor MG132 stabilized TdRL1::GFP expression in RAM cells showing a post-translational regulation. Moreover, immuno-cytochemical analyses of transgenic roots showed that TdRL1 was present in the cytoplasm and within the microtubular spindle of mitotic cells, while, in interphasic cells, it was rather restricted to the cytoplasm with a spotty pattern at the nuclear periphery. Interestingly in cells subjected to stress, TdRL1 was partly relocated into the nucleus. Moreover, TdRL1 transgenic lines showed increased germination rates under salt stress conditions as compared to wild type. This enhanced salt stress tolerance was associated to an alleviation of oxidative damage. Finally, when expressed in the rice rss1 mutant, TdRL1 suppressed its dwarf phenotype upon salt stress, confirming that both proteins are true functional homologs required for salt stress tolerance in cereals.

Mechanisms Behind Resistance to PI3K Inhibitor Treatment Induced by the PIM Kinase

Cancer resistance to PI3K inhibitor therapy can be in part mediated by increases in the PIM1 kinase. However, the exact mechanism by which PIM kinase promotes tumor cell resistance is unknown. Our study unveils the pivotal control of redox signaling by PIM kinases as a driver of this resistance mechanism. PIM1 kinase functions to decrease cellular ROS levels by enhancing nuclear factor erythroid 2-related factor 2 (NRF2)/antioxidant response element activity. PIM prevents cell death induced by PI3K-AKT-inhibitory drugs through a noncanonical mechanism of NRF2 ubiquitination and degradation and translational control of NRF2 protein levels through modulation of eIF4B and mTORC1 activity. Importantly, PIM also controls NAD(P)H production by increasing glucose flux through the pentose phosphate shunt decreasing ROS production, and thereby diminishing the cytotoxicity of PI3K-AKT inhibitors. Treatment with PIM kinase inhibitors reverses this resistance phenotype, making tumors increasingly susceptible to small-molecule therapeutics, which block the PI3K-AKT pathway.

Ethanol extract of Curcuma longa rhizome mitigates potassium bromate-induced liver changes in the Wistar rat: Histological, histochemical and immunohistochemical assessments

The effects of Curcuma longa rhizome on hepatic cells, glycogen, connective tissue fibres and filamentous cytoskeleton were evaluated following KBrO₃-induced liver injury in Wistar rats. Thirty-five male rats were randomly divided into seven groups (n=5). Group 1 were normal saline treated rats. Hepatic injury was induced in groups 2 to 7 by oral administration of 100mg/kg KBrO₃ for 2 weeks. Following induction, rats in group 2 were sacrificed while groups 3, 4, 5 were given oral dose of EECLOR at 100, 200, 400mg/kg respectively. Group 6 rats were treated with silymarine while group 7 rats were left untreated. The rats were sacrificed and the liver sections were stained with H&E, Masson trichrome, Gordon and Sweets, PAS, Feulgen reaction, anti-vimentin antibody for demonstration of general histoarchitecture, elastic fibre, collagen fibre; glycogen, nuclear DNA and filamentous cytoskeleton respectively. Groups 2, 3, 7 developed intranuclear vacuolation, plasma coagulation, plamolysis, karyopyknosis, karyorrhexis and karyolysis, hyperchromatism, DNA fading and pleomorphism. Immunohistochemical study revealed near negative immunoreaction for vimentin. These pathological changes were ameliorated in EECLOR-treated groups in a manner comparable to silymarine-treated group. The study concluded that ameliorative effects of EECLOR in KBrO₃-induced liver injury could be due to its vimentin stabilization property.

Testosterone induced downregulation of migration and proliferation in human Umbilical Vein Endothelial Cells by Androgen Receptor dependent and independent mechanisms

Recent research has emphasized the potential unfavorable effects of declining testosterone (T) levels in men and the putative beneficial effect of androgen therapy in select women. Some controversy surrounding the mechanism of action and the effects of T on endothelium remains. In this study, we evaluated the mechanism of T action on pooled primary Human Umbilical Vein Endothelial Cells (HUVEC) of mixed gender by focusing on two important processes, proliferation and migration. In our in vitro model system, we found that only the supra-physiological dose of T affected these two processes irrespective of the ratio of male to female cells in the pools. At a concentration of 1 μM, T downregulated the proliferation of HUVEC by inducing arrest in the G1 cell cycle phase in an Androgen Receptor (AR)-independent manner. We show that treatment with 1 μM T also induced downregulation of HUVEC migration. This process was AR-dependent and was associated with persistent phosphorylation of ezrin, radixin and moesin. Regardless of the mechanism of action, the treatment of HUVEC with both supra- and physiological doses of T was associated with posttranscriptional stabilization of the AR upon ligand binding.

Ciprofloxacin Enhances TRAIL-Induced Apoptosis in Lung Cancer Cells by Upregulating the Expression and Protein Stability of Death Receptors through CHOP Expression

Ciprofloxacin (CIP) is a potent antimicrobial agent with multiple effects on host cells and tissues. Previous studies have highlighted their proapoptotic effect on human cancer cells. The current study showed that subtoxic doses of CIP effectively sensitized multiple cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. Although TRAIL alone mediated the partial proteolytic processing of procaspase-3 in lung cancer cells, co-treatment with CIP and TRAIL efficiently restored the complete activation of caspases. We found that treatment of lung cancer with CIP significantly upregulated the expression and protein stability of death receptor (DR) 5. These effects were mediated through the regulation of transcription factor CCAT enhancer-binding protein homologous protein (CHOP) since the silencing of these signaling molecules abrogated the effect of CIP. Taken together, these results indicated that the upregulation of death receptor expression and protein stability by CIP contributed to the restoration of TRAIL-sensitivity in lung cancer cells.