Histone H2AX Is Involved in FoxO3a-Mediated Transcriptional Responses to Ionizing Radiation to Maintain Genome Stability

Histone H2AX plays a crucial role in molecular and cellular responses to DNA damage and in the maintenance of genome stability. It is downstream of ataxia telangiectasia mutated (ATM) damage signaling pathway and there is an emerging role of the transcription factor FoxO3a, a regulator of a variety of other pathways, in activating this signaling. We asked whether H2AX may feedback to FoxO3a to affect respective FoxO3a-dependent pathways. We used a genetically matched pair of mouse embryonic fibroblast H2AX+/+ and H2AX−/− cell lines to carry out comprehensive time-course and dose-response experiments and to show that the expression of several FoxO3a-regulated genes was altered in H2AX−/− compared to H2AX+/+ cells at both basal and irradiated conditions. Hspa1b and Gadd45a were down-regulated four- to five-fold and Ddit3, Cdkn1a and Sod2 were up-regulated 2–3-fold in H2AX−/− cells. Using the luciferase reporter assay, we directly demonstrated that transcriptional activity of FoxoO3a was reduced in H2AX−/− cells. FoxO3a localization within the nuclear phospho-ATM (Ser1981) foci in irradiated cells was affected by the H2AX status, as well as its posttranslational modification (phospho-Thr32). These differences were associated with genomic instability and radiosensitivity in H2AX−/− cells. Finally, knockdown of H2AX in H2AX+/+ cells resulted in FoxO3a-dependent gene expression patterns and increased radiosensitivity that partially mimicked those found in H2AX−/− cells. Taken together, our data suggest a role for FoxO3a in the maintenance of genome integrity in response to DNA damage that is mediated by H2AX via yet unknown mechanisms

In utero programming of the postnatal growth and insulin sensitivity after between-breeds transfers in the horse

absen

Programmation foetale des anomalies du métabolisme glucidique, de la croissance osseuse et de la prédisposition à l'ostéochondrose chez le poulain

Article présenté à la 40ème Journée de la Recherche Equine, Paris, le 18 mars 2014absen

In utero programming of the postnatal growth and insulin sensitivity after between-breeds transfers in the horse

Genetics are responsible for determining the growth and size of different breeds of horses. Cross-breed embryo transfers were performed using Pony (P), Saddlebred (S) and Draft (D) horses to study growth and insulin-sensitivity in offspring. Control pregnancies (S-in Sand P-in-P) were obtained by Al. "Lush" pregnancies were obtained by transferring S (S in-D) and P embryos (P-in-D) into D mares. Restricted pregnancies were obtained by transferring S embryos into P mares (S-in-P). At 3 days, 4.5 months and one year, foals underwent an intravenous glucose tolerance test (IVGTT). At 6 and 18 months, insulin sensitivity was determined using a euglycemic hyperinsulinemic clamp. Birthweight was increased in P-in-D and S-in-D vs P-in-P and S-in-S controls (+57.2%,p=0.0007 and +8.9%,p=0.0597, respectively), and restricted in S-in-P vs S-in-S (-31.2%, p=0.0008). P-in O foals remained heavier than P-in-P until 18 months (+38.5%,p=0.0317), whereas S-in-D foals became similar to S-in-S between 6 and 18 months. S-in-P foals caught up with S-in-S foals after 9 months. Insulin response to glucose was increased in S-in-D and P-in-D foals at 3 days (p=0.0393 and p=0.0539), indicating insulin resistance. Results are pending for 4,5 months. Clamps at 6 months demonstrated the development of insulin resistance in P in-P vs S-in-S foals (p=0.0378). P-in-D remained insulin resistant and did not differ from P in-P. S-in-P and S-in-D foals were not different from S-in-S but insulin resistance was increased in S-in-D vs S-in-P foals (p=0.0293). IVGTT at one year and clamps at 18 months of age confirmed the increased insulin resistance of P-in-P vs S-in-S foals (p=0.0487), without effects of embryo transfer. Genetic programming of fetal and post-natal growth can be modified through embryo transfer in a larger or a smaller breed in the equine species and that glucose homeostasis is also affected post-natally. More data on plasma insulin concentrations will be available at the meeting

Enhanced or reduced fetal growth induced by embryo transfer into smaller or larger breeds alters post-natal growth and metabolism in pre-weaning horses

In equids, placentation is diffuse and nutrient supply to the fetus is determined by uterine size. This correlates with maternal size and affects intra-uterine development and subsequent post-natal growth, as well as insulin sensitivity in the newborn. Long-term effects remain to be described. In this study, fetal growth was enhanced or restricted through ET using pony (P), saddlebred (S) and draft (D) horses. Control P-P (n = 21) and S-S (n = 28) pregnancies were obtained by AI. Enhanced and restricted pregnancies were obtained by transferring P or S embryos into D mares (P-D, n = 6 and S-D, n = 8) or S embryos into P mares (S-P, n = 6), respectively. Control and experimental foals were raised by their dams and recipient mothers, respectively. Weight gain, growth hormones and glucose homeostasis were investigated in the foals from birth to weaning. Fetal growth was enhanced in P-D and these foals remained consistently heavier, with reduced T3 concentrations until weaning compared to P-P. P-D had lower fasting glucose from days 30 to 200 and higher insulin secretion than P-P after IVGTT on day 3. Euglycemic clamps in the immediate post-weaning period revealed no difference in insulin sensitivity between P-D and P-P. Fetal growth was restricted in S-P and these foals remained consistently lighter until weaning compared to S-D, with elevated T3 concentrations in the newborn compared to S-S. S-P exhibited higher fasting glycemia than S-S and S-D from days 30 to 200. They had higher maximum increment in plasma glucose than S-D after IVGTT on day 3 and clamps on day 200 demonstrated higher insulin sensitivity compared to S-D. Neither the restricted nor the enhanced fetal environment affected IGF-1 concentrations. Thus, enhanced and restricted fetal and post-natal environments had combined effects that persisted until weaning. They induced different adaptive responses in post-natal glucose metabolism: an early insulin-resistance was induced in enhanced P-D, while S-P developed increased insulin sensitivity

L’exposition maternelle aux gaz d’échappement de moteur diesel au cours de la gestation affecte le développement foeto-placentaire : validation du modèle lapin

Plusieurs études épidémiologiques chez l'Homme ont mon­tré qu'une exposition maternelle à la pollution atmosphé­rique induisait un retard de Croissance Intra-Utérin (RCIU) associée à une diminution du poids placentaire. Cependant, l'exploration plus approfondie des mécanismes reste limitée chez l'Homme.Dans ce projet, nous avons donc développé un modèle lapin afin d'étudier les effets potentiels de la pollution atmosphé­rique au cours de la gestation.Les lapines gestantes ont été exposées à un mélange représentatif de la pollution atmosphérique, c'est-à-dite des gaz d'échappement de moteur diesel dilués (groupe P) ou de l'air filtré (groupe C), lh le matin et lh l'après-midi, 5 jours par semaine, de 3 à 27 jpc (terme = 31 jpc). A 6 jpc, les embryons issus de femelles super-ovulées ont été collectés (N=12 lapines, groupe P et N=11 lapines, groupe C). A 28 jpc, les lapines ont été euthanasiées (N =7 lapines, groupe P et N=6 lapines, groupe C), les fœtus et les placentas ont été collectés, pesés et mesurés. Les données ont été analysées avec des ANOVA en prenant comme co-facteurs la taille de la portée, le sexe fœtal et la mère.Nous avons établi que l'exposition des lapines aux gaz d'échappement n'affecte pas le taux d'implantation. En re­vanche, le nombre d'embryons par lapine est augmenté dans le groupe P par rapport au groupe C à 6dpc.A 28 jpc, 68P et 51C unités fœto-placentaires ont été collectées. Les fœtus P sont plus légers que lesfœtus C (p=0,1640). Le rapport du poids fœtal sur le poids placen­taire est plus faible chez les fœtus du groupe P que ceux du groupe C (p= 0,1309), indiquant une efficacité placentaire réduite. Alors que les poids des zones labyrinthiques et des décidues ne sont pas affectés. Par ailleurs, il existe une corré­lation entre le poids de la zone labyrinthique et le poids de la décidue uniquement observée dans le groupe C.L'exposition maternelle au gaz d'échappement induit une réduction de la longueur du corps, du périmètre abdominal et de la longueur de la tête des fœtus (p=0,1196; p=0,1040 et p=0,1710 respectivement), mais les rapports des poids des poumons, du foie, des reins sur le poids fœtal ne sont pas différents entre les 2 groupes. Par contre, le rapport du poids du cerveau fœtal sur le poids du fœtus est augmenté dans le groupe P (p=0,1031), indiquant que la croissance cérébrale est préservée et que l'exposition maternelle aux gaz d'échappement induit un RCIU disharmonieux.Ces données montrent qu'une exposition répétée au gaz d'échappement de moteur diesel affecte le développement fœto-placentaire et valide l'utilisation du modèle lapin pour la suite des explorations

Search for Scalar Diphoton Resonances in the Mass Range 65−60065-600 GeV with the ATLAS Detector in pppp Collision Data at s\sqrt{s} = 8 TeVTeV

A search for scalar particles decaying via narrow resonances into two photons in the mass range 65–600 GeV is performed using $20.3\text{}\text{}{\mathrm{fb}}^{-1}$ of $\sqrt{s}=8\text{}\text{}\mathrm{TeV}$ $pp$ collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95% confidence level on the production cross section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches