Biobased polymers derived from itaconic acid bearing clickable groups with potent antibacterial activity and negligible hemolytic activity.

Herein, we report, for the first time, the synthesis of clickable polymers derived from biobased itaconic acid, which was then used for the preparation of novel cationic polymers with antibacterial properties and low hemotoxicity via click chemistry. Itaconic acid (IA) was subjected to chemical modification by incorporating clickable alkyne groups on the carboxylic acids. The resulting monomer with pendant alkyne groups was easily polymerized and copolymerized with dimethyl itaconate (DMI) by radical polymerization. The feed molar ratio of comonomers was varied to precisely tune the content of alkyne groups in the copolymers and the amphiphilic balance. Subsequently, an azide with a thiazole group, which is a component of the vitamin thiamine (B1), was attached onto the polymers by copper-catalyzed azidealkyne cycloaddition (CuAAC) click chemistry leading to triazole linkages. N-Alkylation reactions of the thiazole and triazole groups with methyl and butyl iodides provide the corresponding itaconate derivatives with pendant azolium groups. The copolymers with variable cationic charge densities and hydrophobic/ hydrophilic balances, depending on the comonomer feed ratio, display potent antibacterial activity against Gram-positive bacteria, whereas the activity was almost null against Gram-negative bacteria. Hemotoxicity assays demonstrated that the copolymers exhibited negligible hemolysis and excellent selectivity, more than 1000-fold, for Gram-positive bacteria over human red blood cells.post-print1945 K

PLA and PBAT-based electrospun fibers functionalized with antibacterial bio-based polymers

Antimicrobial fibers based on biodegradable polymers, poly(lactic acid) (PLA), and poly(butylene adipate-co-terephthalate) (PBAT) are prepared by electrospinning. For this purpose, a biodegradable/bio-based polyitaconate containing azoles groups (PTTI) is incorporated at 10 wt.% into the electrospinning formulations. The resulting fibers functionalized with azole moieties are uniform and free of beads. Then, the accessible azole groups are subjected to N-alkylation, treatment that provides cationic azolium groups with antibacterial activity at the surface of fibers. The positive charge density, roughness, and wettability of the cationic fibers are evaluated and compared with flat films. It is confirmed that these parameters exert an important effect on the antimicrobial properties, as well as the length of the alkylating agent and the hydrophobicity of the matrix. The quaternized PLA/PTTI fibers exhibit the highest efficiency against the tested bacteria, yielding a 4-Log reduction against S. aureus and 1.7-Log against MRSA. Then, biocompatibility and bioactivity of the fibers are evaluated in terms of adhesion, morphology and viability of fibroblasts. The results show no cytotoxic effect of the samples, however, a cytostatic effect is appreciated, which is ascribed to the strong electrostatic interactions between the positive charge at the fiber surface and the negative charge of the cell membranes

Genomic analysis of the function of the transcription factor gata3 during development of the Mammalian inner ear

We have studied the function of the zinc finger transcription factor gata3 in auditory system development by analysing temporal profiles of gene expression during differentiation of conditionally immortal cell lines derived to model specific auditory cell types and developmental stages. We tested and applied a novel probabilistic method called the gamma Model for Oligonucleotide Signals to analyse hybridization signals from Affymetrix oligonucleotide arrays. Expression levels estimated by this method correlated closely (p<0.0001) across a 10-fold range with those measured by quantitative RT-PCR for a sample of 61 different genes. In an unbiased list of 26 genes whose temporal profiles clustered most closely with that of gata3 in all cell lines, 10 were linked to Insulin-like Growth Factor signalling, including the serine/threonine kinase Akt/PKB. Knock-down of gata3 in vitro was associated with a decrease in expression of genes linked to IGF-signalling, including IGF1, IGF2 and several IGF-binding proteins. It also led to a small decrease in protein levels of the serine-threonine kinase Akt2/PKB beta, a dramatic increase in Akt1/PKB alpha protein and relocation of Akt1/PKB alpha from the nucleus to the cytoplasm. The cyclin-dependent kinase inhibitor p27(kip1), a known target of PKB/Akt, simultaneously decreased. In heterozygous gata3 null mice the expression of gata3 correlated with high levels of activated Akt/PKB. This functional relationship could explain the diverse function of gata3 during development, the hearing loss associated with gata3 heterozygous null mice and the broader symptoms of human patients with Hearing-Deafness-Renal anomaly syndrome

Regulation of Ras.GTP loading and Ras-Raf association in neonatal rat ventricular myocytes by G protein-coupled receptor agonists and phorbol ester. Activation of the extracellular signal-regulated kinase cascade by phorbol ester is mediated by Ras.

The small G protein Ras has been implicated in hypertrophy of cardiac myocytes. We therefore examined the activation (GTP loading) of Ras by the following hypertrophic agonists: phorbol 12-myristate 13-acetate (PMA), endothelin-1 (ET-1), and phenylephrine (PE). All three increased Ras.GTP loading by 10-15-fold (maximal in 1-2 min), as did bradykinin. Other G protein-coupled receptor agonists (e.g. angiotensin II, carbachol, isoproterenol) were less effective. Activation of Ras by PMA, ET-1, or PE was reduced by inhibition of protein kinase C (PKC), and that induced by ET-1 or PE was partly sensitive to pertussis toxin. 8-(4-Chlorophenylthio)-cAMP (CPT-cAMP) did not inhibit Ras.GTP loading by PMA, ET-1, or PE. The association of Ras with c-Raf protein was increased by PMA, ET-1, or PE, and this was inhibited by CPT-cAMP. However, only PMA and ET-1 increased Ras-associated mitogen-activated protein kinase kinase 1-activating activity, and this was decreased by PKC inhibition, pertussis toxin, and CPT-cAMP. PMA caused the rapid appearance of phosphorylated (activated) extracellular signal-regulated kinase in the nucleus, which was inhibited by a microinjected neutralizing anti-Ras antibody. We conclude that PKC- and Gi-dependent mechanisms mediate the activation of Ras in myocytes and that Ras activation is required for stimulation of extracellular signal-regulated kinase by PMA

Antibacterial and compostable polymers derived from biobased itaconic acid as environmentally friendly additives for biopolymers

In this work, a series of antibacterial cationic copolymers derived from bio-sourced itaconic acid was studied as potential biobased active components in biodegradable formulations based on poly(butylene adipate-co-terephthalate) (PBAT) for packaging applications. These copolymers were first characterized by testing their antimicrobial activity against resistant bacterial strains, their biodegradability in compost conditions, and their thermal properties by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The antibacterial properties showed potent activity against Methicillin-resistant Staphylococcus aureus (MRSA), with MIC values as low as 78 μg mL. Related to their biodegradability, the cationic polymers biodegraded fast under compost conditions and even a priming effect was observed in the compost. Thermal properties, characterized by DSC and TGA, showed that the copolymers thermally degraded at temperature relatively low; nevertheless, they are able to be processed at temperatures up to ∼150 °C. Subsequently, these antibacterial polymers were successfully blended as minor active component (10 wt%) with PBAT by melt-extrusion and press-compression molding. The resulting biopolymeric films exhibit potent antibacterial activity, which confirm that the cationic polymers incorporated as active component are able to perverse this activity after the processing and impart antibacterial properties to PBAT bioplastic. Therefore, these antibacterial biobased polymers derived from itaconic acid seem to be good candidates for applications related to active food packaging or even for biomedical devices.This work was funded by the MICINN (PID2019-104600RB-I00), the Agencia Estatal de Investigación (AEI, Spain) and Fondo Europeo de Desarrollo Regional (FEDER, EU) and by CSIC (LINKA20364). A. Chi- loeches acknowledges MICIU for his FPU fellowship FPU18/017

Electrospun Polylactic Acid-Based Fibers Loaded with Multifunctional Antibacterial Biobased Polymers

Here, we report the development of antibacterial and compostable electrospun polylactic acid (PLA) fibers by incorporation of a multifunctional biobased polymer in the process. The multifunctional polymer was synthesized from the bio-sourced itaconic acid building block by radical polymerization followed by click chemistry reaction with hydantoin groups. The resulting polymer possesses triazole and hydantoin groups available for further N-alkylation and chlorination reaction, which provide antibacterial activity. This polymer was added to the electrospinning PLA solution at 10 wt %, and fiber mats were successfully prepared. The obtained fibers were surface-modified through the accessible functional groups, leading to the corresponding cationic triazolium and N-halamine groups. The fibers with both antibacterial functionalities demonstrated high antibacterial activity against Gram-positive and Gram-negative bacteria. While the fibers with cationic surface groups are only effective against Gram-positive bacteria (Staphylococcus epidermidis and Staphylococcus aureus), upon chlorination, the activity against Gram-negative Escherichia coli and Pseudomonas aeruginosa is significantly improved. In addition, the compostability of the electrospun fibers was tested under industrial composting conditions, showing that the incorporation of the antibacterial polymer does not impede the disintegrability of the material. Overall, this study demonstrates the feasibility of this biobased multifunctional polymer as an antibacterial agent for biodegradable polymeric materials with potential application in medical uses.This work was funded by the MICINN (PID2019-104600RBI00), Agencia Estatal de Investigación (AEI, Spain), Fondo Europeo de Desarrollo Regional (FEDER, EU), and CSIC (LINKA20364). A.C. acknowledges MICIU for his FPU fellowship FPU18/01776

PLA and PBAT-Based Electrospun Fibers Functionalized with Antibacterial Bio-Based Polymers

Antimicrobial fibers based on biodegradable polymers, poly(lactic acid) (PLA),and poly(butylene adipate-co-terephthalate) (PBAT) are prepared byelectrospinning. For this purpose, a biodegradable/bio-based polyitaconatecontaining azoles groups (PTTI) is incorporated at 10 wt.% into theelectrospinning formulations. The resulting fibers functionalized with azolemoieties are uniform and free of beads. Then, the accessible azole groups aresubjected toN-alkylation, treatment that provides cationic azolium groupswith antibacterial activity at the surface of fibers. The positive charge density,roughness, and wettability of the cationic fibers are evaluated and comparedwith flat films. It is confirmed that these parameters exert an important effecton the antimicrobial properties, as well as the length of the alkylating agentand the hydrophobicity of the matrix. The quaternized PLA/PTTI fibers exhibitthe highest efficiency against the tested bacteria, yielding a 4-Log reductionagainstS. aureusand 1.7-Log against MRSA. Then, biocompatibility andbioactivity of the fibers are evaluated in terms of adhesion, morphology andviability of fibroblasts. The results show no cytotoxic effect of the samples,however, a cytostatic effect is appreciated, which is ascribed to the strongelectrostatic interactions between the positive charge at the fiber surface andthe negative charge of the cell membranesThis work was funded by the MICINN (PID2019-104600RB-I00), the Agen-cia Estatal de Investigación (AEI, Spain) and Fondo Europeo de DesarrolloRegional (FEDER, EU) and by CSIC (LINKA20364). A.C. acknowledges MI-CIU for his FPU fellowship FPU18/01776. The negativ exponents were cor-rected on January 16, 202

B-RAF is a therapeutic target in melanoma.

B-RAF is a therapeutic target in melanoma B-RAF is a serine/threonine-specific protein kinase that is mutated in approximately 70% of human melanomas. However, the role of this signalling molecule in cancer is unclear. Here, we show that ERK is constitutively activated in melanoma cells expressing oncogenic B-RAF and that this activity is required for proliferation. B-RAF depletion by siRNA blocks ERK activity, whereas A-RAF and C-RAF depletion do not affect ERK signalling. B-RAF depletion inhibits DNA synthesis and induces apoptosis in three melanoma cell lines and we show that the RAF inhibitor BAY43-9006 also blocks ERK activity, inhibits DNA synthesis and induces cell death in these cells. BAY43-9006 targets B-RAF signalling in vivo and induces a substantial growth delay in melanoma tumour xenografts. Our data demonstrate that oncogenic B-RAF activates ERK signalling, induces proliferation and protects cells from apoptosis, demonstrating that it is an important therapeutic target and thus provides novel strategies for clinical management of melanoma and other cancers

Influence of the microenvironment on modulation of the host response by typhoid toxin

Bacterial genotoxins cause DNA damage in eukaryotic cells, resulting in activation of the DNA damage response (DDR) in vitro. These toxins are produced by Gram-negative bacteria, enriched in the microbiota of inflammatory bowel disease (IBD) and colorectal cancer (CRC) patients. However, their role in infection remains poorly characterized. We address the role of typhoid toxin in modulation of the host-microbial interaction in health and disease. Infection with a genotoxigenic Salmonella protects mice from intestinal inflammation. We show that the presence of an active genotoxin promotes DNA fragmentation and senescence in vivo, which is uncoupled from an inflammatory response and unexpectedly associated with induction of an anti-inflammatory environment. The anti-inflammatory response is lost when infection occurs in mice with acute colitis. These data highlight a complex context-dependent crosstalk between bacterial-genotoxin-induced DDR and the host immune response, underlining an unexpected role for bacterial genotoxins. © 2021 The Author(s