DeltaNp73 transcription factors modulate cell survival and tumor development

The p73 locus encodes two types of transcription factors: full length pro-apoptotic isoforms (TAp73), and N-terminally truncated anti-apoptotic proteins (DeltaNp73). To study the function of DeltaNp73 in vivo, we generated mutant mice in which DeltaNp73 is inactivated, but TAp73 expression is intact. In addition, we knocked in the locus the Cre recombinase, and the enhanced green fluorescent protein (EGFP). Using this allele, we refined the expression of DeltaNp73 during brain development and emphasized the importance of the thalamic eminence, a transient source that contributes neurons to the telencephalon. We showed that DeltaNp73 inactivation increases apoptosis in neurons. (1) We also investigated the role of DeltaNp73 in carcinogenesis by inducing tumors with methylcholanthrene in mutant and control mice, and found that mutant females, but not males, have decreased propensity to tumor development. Both effects on neuronal apoptosis and tumor development were milder than predicted from in vitro studies

DeltaNp73 transcription factors modulate cell survival and tumor development

The p73 locus encodes two types of transcription factors: full length pro-apoptotic isoforms (TAp73), and N-terminally truncated anti-apoptotic proteins (DeltaNp73). To study the function of DeltaNp73 in vivo, we generated mutant mice in which DeltaNp73 is inactivated, but TAp73 expression is intact. In addition, we knocked in the locus the Cre recombinase, and the enhanced green fluorescent protein (EGFP). Using this allele, we refined the expression of DeltaNp73 during brain development and emphasized the importance of the thalamic eminence, a transient source that contributes neurons to the telencephalon. We showed that DeltaNp73 inactivation increases apoptosis in neurons. (1) We also investigated the role of DeltaNp73 in carcinogenesis by inducing tumors with methylcholanthrene in mutant and control mice, and found that mutant females, but not males, have decreased propensity to tumor development. Both effects on neuronal apoptosis and tumor development were milder than predicted from in vitro studies

Refonte de l'organisation et de la gestion

L’organisation et la gestion des activités de coopération pour le développement menées par la CE s’inscrivent dans le contexte plus vaste et plus politique des relations extérieures. Les réformes en cours visent notamment l’adoption d’approches plus stratégiques et simplifiées, la réorganisation des services centraux et la "déconcentration" des responsabilités en matière de mise en œuvre, vers les missions locales. Elles contribuent à définir plus précisément la vision, les compétences et les méthodes des institutions européennes chargées de l'aide. Il sera essentiel de veiller à ce que ces réformes de l’organisation et de la gestion soient de plus en plus largement orientées vers les résultats. La mise en place de cette nouvelle culture de gestion vient tout juste d’être entreprise et elle ne pourra être réussie sans un engagement politique à long terme des responsables européens. Cette approche plus stratégique et davantage orientée vers le développement requiert aussi des ressources humaines plus nombreuses.

Induction of serpinb1a by PACAP or NGF is required for PC12 cells survival after serum withdrawal

Abstract Thumbnail image of graphical abstract PC12 cells are used to study the signaling mechanisms underlying the neurotrophic and neuroprotective activities of pituitary adenylate cyclase-activating polypeptide (PACAP) and nerve growth factor (NGF). Previous microarray experiments indicated that serpinb1a was the most induced gene after 6 h of treatment with PACAP or NGF. This study confirmed that serpinb1a is strongly activated by PACAP and NGF in a time-dependent manner with a maximum induction (~ 50-fold over control) observed after 6 h of treatment. Co-incubation with PACAP and NGF resulted in a synergistic up-regulation of serpinb1a expression (200-fold over control), suggesting that PACAP and NGF act through complementary mechanisms. Consistently, PACAP-induced serpinb1a expression was not blocked by TrkA receptor inhibition. Nevertheless, the stimulation of serpinb1a expression by PACAP and NGF was significantly reduced in the presence of extracellular signal-regulated kinase, calcineurin, protein kinase A, p38, and PI3K inhibitors, indicating that the two trophic factors share some common pathways in the regulation of serpinb1a. Finally, functional investigations conducted with siRNA revealed that serpinb1a is not involved in the effects of PACAP and NGF on PC12 cell neuritogenesis, proliferation or body cell volume but mediates their ability to block caspases 3/7 activity and to promote PC12 cell survival. Pituitary adenylate cyclase-activating polypeptide (PACAP) and nerve growth factor (NGF) induce a strong increase in serpinb1 a expression in PC12 cells. Functional investigations revealed that this increase in serpinb1a does not affect cell proliferation or differentiation but inhibits caspase 3 activity and promotes cell survival.link_to_OA_fulltex

Effects of PACAP in the Local Regulation of Endocrine Glands

International audiencePituitary adenylate cyclase-activating polypeptide (PACAP), a peptide of the vasoactive intestinal polypep-tide (VIP)-glucagon superfamily, was initially characterized by virtue of its ability to stimulate cAMP formation in cultured rat anterior pituitary cells. Three PACAP receptors have been cloned so far: a PACAP-selective receptor, termed PAC1-R, and two PACAP/VIP common receptors, termed VPAC1-R and VPAC2-R. PACAP and its receptors are widely expressed in the brain and in peripheral organs, notably in the hypothalamus and in endocrine glands. Indeed, there is now clear evidence that PACAP exerts neuroendocrine, paracrine, and autocrine control of the activity of the pituitary, thyroid, testis, ovary, adrenal medulla, adrenal cortex, and endocrine pancreas. These observations suggest that selective PACAP agonists and antagonists could have therapeutic value for the treatment of various endo-crine disorders

Peroxiredoxin 2 is Involved in the Neuroprotective Effects of PACAP in Cultured Cerebellar Granule Neurons

International audienceThe neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is known to counteract in vitro the deleterious effects of toxic agents on cerebellar granule cell survival and differentiation. The potent antiapoptotic action of PACAP is mediated through inhibition of caspase-3 activity; however, additional proteins are likely involved and remain to be identified. Two-dimensional gel electrophoresis analysis coupled with mass spectrometry characterization led to the identification of a protein, peroxiredoxin 2, which was induced after a 6-h treatment with PACAP. Western blot analysis confirmed the regulation of peroxiredoxin 2 by PACAP and revealed that this protein is induced by both cyclic AMP and protein kinase C stimulators. Inhibition of peroxiredoxin 2 expression, using two distinct small-interfering RNAs (siRNAs), reduced the effect of PACAP on caspase-3 activity and cerebellar granule cell survival. Peroxiredoxin 2 expression was also induced in vivo and in vitro by ethanol. Although ethanol and PACAP exert opposite effects on caspase-3 activity, inhibition of peroxiredoxin 2 expression, using siRNAs, only reduced the ability of PACAP to prevent ethanol-induced caspase-3 activity. Taken together, these data indicate that peroxiredoxin 2 is probably involved in the neurotrophic effect of PACAP and suggest that this protein may have a therapeutic potential for the treatment of some neurodegenerative disease

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates the expression and the release of tissue plasminogen activator (tPA) in neuronal cells: involvement of tPA in the neuroprotective effect of PACAP.

International audiencePituitary adenylate cyclase-activating polypeptide (PACAP) and tissue plasminogen activator (tPA) play important roles in neuronal migration and survival. However, a direct link between the neurotrophic effects of PACAP and tPA has never been investigated. In this study, we show that, in PC12 cells, PACAP induced a 9.85-fold increase in tPA gene expression through activation of the protein kinase A- and protein kinase C-dependent signaling pathways. In immature cerebellar granule neurons (CGN), PACAP stimulated tPA mRNA expression and release of proteolytically active tPA. Immunocytochemical labeling revealed the presence of tPA in the cytoplasm and processes of cultured CGN. The inhibitory effect of PACAP on CGN motility was not affected by the tPA substrate plasminogen or the tPA inhibitor plasminogen activator inhibitor-1. In contrast, plasminogen activator inhibitor-1 significantly reduced the stimulatory effect of PACAP on CGN survival. Altogether, these data indicate that tPA gene expression is activated by PACAP in both tumoral and normal neuronal cells. The present study also demonstrates that PACAP stimulates the release of tPA which promotes CGN survival by a mechanism dependent of its proteolytic activity