Differential Gene Expression Induced by Insulin and Insulin-like Growth Factor-II through the Insulin Receptor Isoform A *

The human insulin receptor (IR) exists in two isoforms (IR-A and IR-B). IR-A is a short isoform, generated by the skipping of exon 11, a small exon encoding for 12 amino acid residues at the carboxyl terminus of the IR alpha-subunit. Recently, we found that IR-A is the predominant isoform in fetal tissues and malignant cells and binds with a high affinity not only insulin but also insulin-like growth factor-II (IGF-II). To investigate whether the activation of IR-A by the two ligands differentially activate post-receptor molecular mechanisms, we studied gene expression in response to IR-A activation by either insulin or IGF-II, using microarray technology. To avoid the interfering effect of the IGF-IR, IGF-II binding to the IR-A was studied in IGF-IR-deficient murine fibroblasts (R- cells) transfected with the human IR-A cDNA (R-/IR-A cells). Gene expression was studied at 0.5, 3, and 8 h. We found that 214 transcripts were similarly regulated by insulin and IGF-II, whereas 45 genes were differentially transcribed. Eighteen of these differentially regulated genes were responsive to only one of the two ligands (12 to insulin and 6 to IGF-II). Twenty-seven transcripts were regulated by both insulin and IGF-II, but a significant difference between the two ligands was present at least in one time point. Interestingly, IGF-II was a more potent and/or persistent regulator than insulin for these genes. Results were validated by measuring the expression of 12 genes by quantitative real-time reverse transcriptase-PCR. In conclusion, we show that insulin and IGF-II, acting via the same receptor, may differentially affect gene expression in cells. These studies provide a molecular basis for understanding some of the biological differences between the two ligands and may help to clarify the biological role of IR-A in embryonic/fetal growth and the selective biological advantage that malignant cells producing IGF-II may acquire via IR-A overexpression

Insulin/Insulin-like Growth Factor I Hybrid Receptors Have Different Biological Characteristics Depending on the Insulin Receptor Isoform Involved

The insulin receptor (IR) and the insulin-like growth factor I receptor (IGF-IR) have a highly homologous structure, but different biological effects. Insulin and IGF-I half-receptors can heterodimerize, leading to the formation of insulin/IGF-I hybrid receptors (Hybrid-Rs) that bind IGF-I with high affinity. As the IR exists in two isoforms (IR-A and IR-B), we evaluated whether the assembly of the IGF-IR with either IR-A or IR-B moieties may differently affect Hybrid-R signaling and biological role. Three different models were studied: (a) 3T3-like mouse fibroblasts with a disrupted IGF-IR gene (R(-) cells) cotransfected with the human IGF-IR and with either the IR-A or IR-B cDNA; (b) a panel of human cell lines variably expressing the two IR isoforms; and (c) HepG2 human hepatoblastoma cells predominantly expressing either IR-A or IR-B, depending on their differentiation state. We found that Hybrid-Rs containing IR-A (Hybrid-Rs(A)) bound to and were activated by IGF-I, IGF-II, and insulin. By binding to Hybrid-Rs(A), insulin activated the IGF-I half-receptor beta-subunit and the IGF-IR-specific substrate CrkII. In contrast, Hybrid-Rs(B) bound to and were activated with high affinity by IGF-I, with low affinity by IGF-II, and insignificantly by insulin. As a consequence, cell proliferation and migration in response to both insulin and IGFs were more effectively stimulated in Hybrid-R(A)-containing cells than in Hybrid-R(B)-containing cells. The relative abundance of IR isoforms therefore affects IGF system activation through Hybrid-Rs, with important consequences for tissue-specific responses to both insulin and IGFs

Master curves for the mechanical reinforcement of diene elastomers with sp2 carbon allotropes

sp2 carbon allotropes are efficient reinforcing fillers for polymer melt and elastomers: carbon black (CB) has been used since early 1900’s and nanofillers such as carbon nanotubes (CNT), graphene and graphene related materials (GRM) have increased their importance over the last decades. Nanofillers can definitely establish larger interfacial area with the polymer matrix than CB and great impact on material properties is thus expected. However, it is widely acknowledged that they will not be able to completely replace CB. Hence, increasing research efforts are on hybrid systems based on CB-CNT and CB-GRM [1]. Research objective is to identify common features and behaviour of nano (CNT, GRM) and nanostructured (CB) sp2 carbon allotropes. In this work, initial modulus was determined by means of dynamic-mechanical shear measurements of composites based on either poly(1,4-cis-isoprene) or poly(styrene-co-butadiene) as the rubber and either CB or CNT or GRM or hybrid systems as the reinforcing fillers. Filler-polymer interfacial area (i.a.), calculated as the product of filler surface area, density and volume fraction, was used to establish a common correlation with the composite initial modulus. A sort of master curve was derived, able to fit all the points up to interfacial area of about 27 μm-1, corresponding to remarkable filler content. Much better efficiency was shown by carbon fillers, when composites were prepared through latex blending. To allow easy dispersion in rubber latex, sp2 carbon allotropes were functionalized with a serinol derivative: 2-(2,5-dimethyl- 1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP) [2, 3], shown in Figure 1

Role of c-Abl in Directing Metabolic versus Mitogenic Effects in Insulin Receptor Signaling

c-Abl is a cytoplasmic tyrosine kinase involved in several signal transduction pathways. Here we report that c-Abl is involved also in insulin receptor signaling. Indeed, c-Abl tyrosine kinase is activated upon insulin stimulation. Inhibition of c-Abl tyrosine kinase by STI571 attenuates the effect of insulin on Akt/GSK-3beta phosphorylation and glycogen synthesis, and at the same time, it enhances the effect of insulin on ERK activation, cell proliferation, and migration. This effect of STI571 is specific to c-Abl inhibition, because it does not occur in Abl-null cells and is restored in c-Abl-reconstituted cells. Numerous evidences suggest that focal adhesion kinase (FAK) is involved in mediating this c-Abl effect. First, anti-phosphotyrosine blots indicate that c-Abl tyrosine kinase activation is concomitant with FAK dephosphorylation in response to insulin, whereas c-Abl inhibition is accompanied by FAK phosphorylation in response to insulin, a response similar to that observed with IGF-I. Second, the c-Abl effects on insulin signaling are not observed in cells devoid of FAK (FAK(-/-) cells). Taken together these results suggest that c-Abl activation by insulin, via a modification of FAK response, may play an important role in directing mitogenic versus metabolic insulin receptor signaling

The Inorganic Side of NGF: Copper(II) And Zinc(II) Affect the NGF Mimicking Signalling of the N-Terminus Peptides Encompassing the Recognition Domain of TrkA Receptor

The nerve growth factor (NGF) N-terminus peptide, NGF(1-14), and its acetylated form, Ac-NGF(1-14), were investigated to scrutinise the ability of this neurotrophin domain to mimic the whole protein. Theoretical calculations demonstrated that non-covalent forces assist the molecular recognition of TrkA receptor for both peptides. Combined parallel tempering/docking simulations discriminated the effect of the N-terminal acetylation on the recognition of NGF(1-14) towards the domain 5 of TrkA (TrkA-D5). Experimental findings demonstrated that both NGF(1-14) and Ac-NGF(1-14) activate TrkA signaling pathways essential for neuronal survival. The NGF-induced TrkA internalization was slightly inhibited in the presence of Cu2+ and Zn2+ ions, whereas the metal ions elicited the NGF(1-14)-induced internalization of TrkA and no significant differences were found in the weak Ac-NGF(1-14)-induced receptor internalization. The crucial role of the metals was confirmed by experiments with the metal-chelator bathocuproine disulfonic acid, which discriminated different levels of inhibitory effects in the signalling cascade, due to different metal affinity of NGF, the free amino and the acetylated peptides. The NGF signaling cascade, activated by NGF (1−14) and Ac-NGF(1-14), induced CREB phosphorylation, but the copper addition further stimulated the Akt, ERK and CREB phosphorylation only for NGF and NGF(1-14). A dynamic and quick influx of both peptides into PC12 cells was tracked by live cell imaging with confocal microscopy. A significant role of copper ions was found in the modulation of peptide sub-cellular localization, especially at the nuclear level. Furthermore, a strong copper ionophoric ability of NGF(1-14) was measured. The Ac-NGF(1-14) peptide, which binds copper ions with a lower stability constant than NGF(1-14), exhibited a lower nuclear localization with respect to the total cellular uptake. These findings were correlated to the metal-induced increase of CREB and BDNF expression upon NGF(1-14) stimulation. In summary, we here validate NGF(1-14) and Ac-NGF(1-14) as first examples of monomer and linear peptides able to activate the NGF-TrkA signaling cascade. Metal ions modulate the activity of both NGF protein and the NGF-mimicking peptides. Such findings demonstrate that NGF(1-14) sequence can reproduce the signal transduction of whole protein, therefore represent a very promising drug candidate for further preclinical studies

Anisotropic effects and master curves for rubbers with sp2 carbon allotropes towards light weight materials

This work presents the preparation of lightweight rubber materials with nanosized sp2 carbon allotropes and discusses the anisotropic nonlinear mechanical behavior of composites based on these nanofillers. Composites were prepared with either poly(styrene-co-butadiene) or poly(1,4-cis-isoprene) as the polymer matrix and either carbon black (CB) or carbon nanotubes (CNT) or hybrid CB/CNT as the filler systems. The initial modulus of the composite (G’min) was determined through dynamic mechanical shear tests and was correlated with the specific interfacial area (i.a.), calculated through the product of filler surface area, density and volume fraction. Common correlation was established, the equation of the common interpolating curve was derived and was used to design composites with the same modulus and lower density, substituting part of CB with lower amount of the carbon allotrope with larger surface area, CNT. Anisotropic nonlinear mechanical behavior was found for nanocomposites based on CNT and poly(1,4-cis-isoprene), prepared by melt blending, calendering and compression molding. An orthotropic and transversally isotropic response was observed: dynamic-mechanical moduli were very similar inside the sheet plane and very different from those in the orthogonal direction. Hence, energy dissipation is not isotropic in CNT filled rubber composites. Such mechanical behavior was correlated with the material structure: alternate areas containing large or low CNT amount and preferential orientation of CNT were observed. In spite of this anisotropic behavior, the validity of the above mentioned mastercurve was confirmed

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Measurement of the W-boson mass in pp collisions at √s=7 TeV with the ATLAS detector

A measurement of the mass of the W boson is presented based on proton–proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb−1 of integrated luminosity. The selected data sample consists of 7.8×106 candidates in the W→μν channel and 5.9×106 candidates in the W→eν channel. The W-boson mass is obtained from template fits to the reconstructed distributions of the charged lepton transverse momentum and of the W boson transverse mass in the electron and muon decay channels, yielding mW=80370±7 (stat.)±11(exp. syst.) ±14(mod. syst.) MeV =80370±19MeV, where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty. A measurement of the mass difference between the W+ and W−bosons yields mW+−mW−=−29±28 MeV

First neutrino interaction candidates at the LHC

FASER$\nu$ at the CERN Large Hadron Collider (LHC) is designed to directly detect collider neutrinos for the first time and study their cross sections at TeV energies, where no such measurements currently exist. In 2018, a pilot detector employing emulsion films was installed in the far-forward region of ATLAS, 480 m from the interaction point, and collected 12.2 fb$^{-1}$ of proton-proton collision data at a center-of-mass energy of 13 TeV. We describe the analysis of this pilot run data and the observation of the first neutrino interaction candidates at the LHC. This milestone paves the way for high-energy neutrino measurements at current and future colliders.Comment: Auxiliary materials are available at https://faser.web.cern.ch/fasernu-first-neutrino-interaction-candidate