Tcf7l2 plays pleiotropic roles in the control of glucose homeostasis, pancreas morphology, vascularization and regeneration

Type 2 diabetes (T2D) is a disease characterized by impaired insulin secretion. The Wnt signaling transcription factor Tcf7l2 is to date the T2D-associated gene with the largest effect on disease susceptibility. However, the mechanisms by which TCF7L2 variants affect insulin release from \u3b2-cells are not yet fully understood. By taking advantage of a tcf7l2 zebrafish mutant line, we first show that these animals are characterized by hyperglycemia and impaired islet development. Moreover, we demonstrate that the zebrafish tcf7l2 gene is highly expressed in the exocrine pancreas, suggesting potential bystander effects on \u3b2-cell growth, differentiation and regeneration. Finally, we describe a peculiar vascular phenotype in tcf7l2 mutant larvae, characterized by significant reduction in the average number and diameter of pancreatic islet capillaries. Overall, the zebrafish Tcf7l2 mutant, characterized by hyperglycemia, pancreatic and vascular defects, and reduced regeneration proves to be a suitable model to study the mechanism of action and the pleiotropic effects of Tcf7l2, the most relevant T2D GWAS hit in human populations

OXPHOS complex impairment and mitochondrial DNA depletion modify hypoxia signaling pathway activity in zebrafish.

Mitochondria are essential for cell survival and health, utilizing about 90% of the oxygen we breath for OXPHOS. Previous studies showed a strong relationship between mitochondrial alterations and hypoxia signaling pathway, an interesting aspect to be investigated. POLG-related disorders are a group of diseases characterized by the dysfunction of DNA polymerase gamma, an enzyme crucial for mtDNA replication, repair and stability. Danio rerio (zebrabish) is an ideal vertebrate model of human mitochondrial diseases because of its high conservation of physiological processes and genomic structure, transgenic lines availability and embryonic transparency. Using zebrabish embryos, we have performed a transient knock-down of the polg gene, inducing a dilated cardiomyopathy and an increased heart bit rate. Moreover, we have developed a transgenic line able to show in vivo the activation of hypoxia-inducible factor 1 (Hif1) signaling. Taking advantage of this reporter line, we established that Hypoxia pathway is up-regulated in polg morphants. In addition, using a pharmacological approach targeting OXPHOS complexes NADH:ubiquinone reductase (Complex I) and Succinate dehydrogenase (Complex II), we have investigated the effect of mitochondrial dysfunctions on the Hypoxia pathway. We established that Hypoxia pathway is signibicantly reduced, both in normoxia and in hypoxia conditions, perhaps due to an increase in ROS production. In conclusion, our data suggest the existence of cross-talk mechanisms sensing mitochondrial dysfunction and changing Hypoxia signaling. In addition, our results on polg transient inactivation incourage the use of zebrabish as a suitable model to perform CRISPR/Cas9-mediated mutagenesis of DNA polymerase gamma, an ongoing project in our laboratory

OXPHOS complex impairment and mitochondrial DNA depletion modify hypoxia signaling pathway activity in zebrafish.

Mitochondria are essential for cell survival and health, utilizing about 90% of the oxygen we breath for OXPHOS. Previous studies showed a strong relationship between mitochondrial alterations and hypoxia signaling pathway, an interesting aspect to be investigated. POLG-related disorders are a group of diseases characterized by the dysfunction of DNA polymerase gamma, an enzyme crucial for mtDNA replication, repair and stability. Danio rerio (zebrabish) is an ideal vertebrate model of human mitochondrial diseases because of its high conservation of physiological processes and genomic structure, transgenic lines availability and embryonic transparency. Using zebrabish embryos, we have performed a transient knock-down of the polg gene, inducing a dilated cardiomyopathy and an increased heart bit rate. Moreover, we have developed a transgenic line able to show in vivo the activation of hypoxia-inducible factor 1 (Hif1) signaling. Taking advantage of this reporter line, we established that Hypoxia pathway is up-regulated in polg morphants. In addition, using a pharmacological approach targeting OXPHOS complexes NADH:ubiquinone reductase (Complex I) and Succinate dehydrogenase (Complex II), we have investigated the effect of mitochondrial dysfunctions on the Hypoxia pathway. We established that Hypoxia pathway is signibicantly reduced, both in normoxia and in hypoxia conditions, perhaps due to an increase in ROS production. In conclusion, our data suggest the existence of cross-talk mechanisms sensing mitochondrial dysfunction and changing Hypoxia signaling. In addition, our results on polg transient inactivation incourage the use of zebrabish as a suitable model to perform CRISPR/Cas9-mediated mutagenesis of DNA polymerase gamma, an ongoing project in our laboratory

Mitochondrial DNA depletion and OXPHOS complex impairment modify Hypoxia signaling pathway activity in zebrafish

none8siMitochondria are essential for cell survival and health, utilizing about 90% of the oxygen we breathe for OXPHOS. Previous studies showed a strong relationship between mitochondrial alterations and hypoxia signaling pathway [1]. POLG-related disorders are a group of diseases characterized by the dysfunction of DNA polymer- ase gamma, crucial for mtDNA replication, repair and stability [2]. Danio rerio (zebrafish) is an ideal vertebrate model of human mitochondrial diseases because of its high conservation of physio- logical processes and genomic structure, transgenic lines availability and embryonic transparency. Using zebrafish embryos, we have performed transient knock-down of the polg gene, inducing a dilated cardiomyopathy and an increased heart bit rate. Moreover, we have developed a transgenic line able to show in vivo the activation of hypoxia-inducible factor 1 (Hif1) signaling. Taking advantage of this reporter line, we established that Hypoxia pathway is up-regulated in polg morphants, maybe due to an increase in ROS production. In addition, using a pharmacological approach targeting OXPHOS complexes, we observed that the inhibition of complexes I and II induces a decrease in Hif1 activation, also in hypoxic conditions. In conclusion, the evidence of Hypoxia reporter activation in polg knock-down embryos suggests the existence of cross-talk mechanisms sensing mitochondrial dysfunction and changing hypoxia signaling, as also confirmed by the OXPHOS complex inhibitors analysis.Biochimica et Biophysica Acta (BBA) - Bioenergetics Volume 1857, Supplement, Pages e1-e128 (August 2016) 2016 EBEC Abstracts Edited by Paolo Bernardi ISSN: 0005-2728mixedTiso, Natascia; Martorano, Laura; Busolin, Giorgia; Ek, Olivier; Facchinello, Nicola; Vanzi, Francesco; Vettori, Andrea; Argenton, FrancescoTiso, Natascia; Martorano, Laura; Busolin, Giorgia; Ek, OLIVIER FREDERIC D; Facchinello, Nicola; Vanzi, Francesco; Vettori, Andrea; Argenton, Francesc

The zebrafish, a teleost model recapitulating the mammalian molecular events during endocrine development and function

In the last decades, the tropical teleost zebrafish (Danio rerio) has proved to be an excellent vertebrate system to model mammalian molecular events occurring during embryonic development, organ formation and adult physiology, either under normal or pathological conditions. Low costs and small dimensions, external fertilization and high fecundity, tissue transparency, rapid development, availability of mutant and transgenic lines, easy manipulability for gene perturbation and pharmacological screening, are some examples of the advantages characterizing this model organism. In the past 15 years, the use of zebrafish in the endocrinology field has been mainly focused on the analysis of endocrine organ development. Our team and other research groups have elucidated the main steps leading to the formation of endocrine glands such as pancreatic islets and thyroid, hypothalamus and pituitary, interrenal gland and gonads. Comparison of the zebrafish endocrine system to that of mammals has demonstrated that the systems are sufficiently similar for zebrafish to be employed as a model for endocrine research. In more recent years, new zebrafish-based tools have been generated to elucidate in vivo the molecular cross-talks occurring among cells, tissues and organs. Signalling pathway reporter lines represent an interesting implementation of classical transgenesis to visualize in vivo, in an intact organism, the anatomical regions that, in a given time interval, are responding to a specific signalling pathway. To generate these transgenic fish lines, signal specific responsive sequences, identified at the genomic level, are multimerized and placed upstream of reporter genes, typically encoding for fluorescent proteins such as GFP or mCherry. At present, a series of pathway reporter lines are already available, among which Bmp, Shh, FGF, Notch, TGF\u3b2, Wnt, hypoxia and glucocorticoid signalling. Our group is currently generating and validating additional lines, among which the cAMP/CREB pathway, while others, such as thyroid hormone and Foxo signalling, are in the planning phase. Preliminary results and envisaged applications will be presented and discussed

A study of C ⁣PC\!P violation in the decays B±→[K+K−π+π−]Dh±B^\pm\to[K^+K^-\pi^+\pi^-]_D h^{\pm} (h=K,πh = K, \pi) and B±→[π+π−π+π−]Dh±B^\pm\to[\pi^+\pi^-\pi^+\pi^-]_D h^{\pm}

The first study of $C\!P$ violation in the decay mode $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^{\pm}$, with $h=K,\pi$, is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of $9$ fb$^{-1}$. The analysis is performed in bins of phase space, which are optimised for sensitivity to local $C\!P$ asymmetries. $C\!P$-violating observables that are sensitive to the angle $\gamma$ of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^{\pm}$ and $B^\pm\to[\pi^+\pi^-\pi^+\pi^-]_D h^{\pm}$ decays.The first study of $C\!P$ violation in the decay mode {{B} ^\pm } \rightarrow [{{K} ^+} {{K} ^-} {{\uppi } ^+} {{\uppi } ^-} ]_{D} h^\pm , with $h=K,\pi$, is presented, exploiting a data sample of proton–proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of $9\text {\,fb} ^{-1}$. The analysis is performed in bins of phase space, which are optimised for sensitivity to local $C\!P$ asymmetries. $C\!P$-violating observables that are sensitive to the angle $\gamma$ of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for {{B} ^\pm } \rightarrow [{{K} ^+} {{K} ^-} {{\uppi } ^+} {{\uppi } ^-} ]_{D} h^\pm and {{B} ^\pm } \rightarrow [{{\uppi } ^+} {{\uppi } ^-} {{\uppi } ^+} {{\uppi } ^-} ]_{D} h^\pm decays.The first study of $C\!P$ violation in the decay mode $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^\pm$, with $h=K,\pi$, is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of $9$ fb$^{-1}$. The analysis is performed in bins of phase space, which are optimised for sensitivity to local $C\!P$ asymmetries. $C\!P$-violating observables that are sensitive to the angle $\gamma$ of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^\pm$ and $B^\pm\to[\pi^+\pi^-\pi^+\pi^-]_D h^\pm$ decays

Search for the rare hadronic decay Bs0→ppˉB_s^0\to p \bar{p}

A search for the rare hadronic decay Bs0→pp¯ is performed using proton-proton collision data recorded by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6  fb-1. No evidence of the decay is found and an upper limit on its branching fraction is set at B(Bs0→pp¯)&lt;4.4(5.1)×10-9 at 90% (95%) confidence level; this is currently the world’s best upper limit. The decay mode B0→pp¯ is measured with very large significance, confirming the first observation by the LHCb experiment in 2017. The branching fraction is determined to be B(B0→pp¯)=(1.27±0.15±0.05±0.04)×10-8, where the first uncertainty is statistical, the second is systematic and the third is due to the external branching fraction of the normalization channel B0→K+π-. The combination of the two LHCb measurements of the B0→pp¯ branching fraction yields B(B0→pp¯)=(1.27±0.13±0.05±0.03)×10-8.A search for the rare hadronic decay $B_s^0\to p \bar{p}$ is performed using proton-proton collision data recorded by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb$^{-1}$. No evidence of the decay is found and an upper limit on its branching fraction is set at ${\cal B}(B_s^0\to p \bar{p}) < 4.4~(5.1) \times 10^{-9}$ at 90% (95%) confidence level; this is currently the world's best upper limit. The decay mode $B^0\to p \bar{p}$ is measured with very large significance, confirming the first observation by the LHCb experiment in 2017. The branching fraction is determined to be ${\cal B}(B^0\to p \bar{p}) = \rm (1.27 \pm 0.15 \pm 0.05 \pm 0.04) \times 10^{-8}$, where the first uncertainty is statistical, the second is systematic and the third is due to the external branching fraction of the normalization channel $B^0\to K^+\pi^-$. The combination of the two LHCb measurements of the $B^0\to p \bar{p}$ branching fraction yields ${\cal B}(B^0\to p \bar{p}) = \rm (1.27 \pm 0.13 \pm 0.05 \pm 0.03) \times 10^{-8}$

Nuclear modification factor of neutral pions in the forward and backward regions in ppPb collisions

The nuclear modification factor of neutral pions is measured in proton-lead collisions collected at a center-of-mass energy per nucleon of $8.16$ TeV with the LHCb detector. The $\pi^0$ production cross section is measured differentially in transverse momentum ($p_{T}$) for 1.5π0 production cross section is measured differentially in transverse momentum (pT) for 1.5<pT<10.0  GeV and in center-of-mass pseudorapidity (ηc.m.) regions 2.5<ηc.m.<3.5 (forward) and -4.0<ηc.m.<-3.0 (backward) defined relative to the proton beam direction. The forward measurement shows a sizable suppression of π0 production, while the backward measurement shows the first evidence of π0 enhancement in proton-lead collisions at the LHC. Together, these measurements provide precise constraints on models of nuclear structure and particle production in high-energy nuclear collisions.The nuclear modification factor of neutral pions is measured in proton-lead collisions collected at a center-of-mass energy per nucleon of 8.16~{\rm TeV}$with the LHCb detector. The$\pi^0$production cross section is measured differentially in transverse momentum ($p_{\rm T}$) for$1.5<p_{\rm T}<10.0~{\rm GeV}$and in center-of-mass pseudorapidity ($\eta_{\rm c.m.}$) regions$2.5<\eta_{\rm c.m.}<3.5$(forward) and$-4.0<\eta_{\rm c.m.}<-3.0$(backward) defined relative to the proton beam direction. The forward measurement shows a sizable suppression of$\pi^0$production, while the backward measurement shows the first evidence of$\pi^0$ enhancement in proton-lead collisions at the LHC. Together, these measurements provide precise constraints on models of nuclear structure and particle production in high-energy nuclear collisions