Ultrastructural and transcriptional profiling of neuropathological misregulation of CREB function

We compare here the neurodegenerative processes observed in the hippocampus of bitransgenic mice with chronically altered levels of cAMP-response element-binding protein (CREB) function. The combination of genome-wide transcriptional profiling of degenerating hippocampal tissue with microscopy analyses reveals that the sustained inhibition of CREB function in A-CREB mice is associated with dark neuron degeneration, whereas its strong chronic activation in VP16-CREB mice primarily causes excitotoxic cell death and inflammation. Furthermore, the meta-analysis with gene expression profiles available in public databases identifies relevant common markers to other neurodegenerative processes and highlights the importance of the immune response in neurodegeneration. Overall, these analyses define the ultrastructural and transcriptional signatures associated with these two forms of hippocampal neurodegeneration, confirm the importance of fine-tuned regulation of CREB-dependent gene expression for CA1 neuron survival and function, and provide novel insight into the function of CREB in the etiology of neurodegenerative processes. © 2010 Macmillan Publishers Limited All rights reserved.The work at AB and LMV laboratory was supported by the European Commission Coordination Action ENINET (contract number LSHM-CT-2005-19063), the Spanish Ministry of Science and Innovation grants BFU2005-00286, CSD2007-00023, and SAF2008-00611, the Generalitat Valenciana grant GVPRE/2008/365, and the Fundació La Marató de TV3 grant 063510. The work at RL laboratory was supported by the Spanish Ministry of Science and Innovation grant BFU2006-01896 and the Junta de Comunidades de Castilla-La Mancha grant PAI08-0174-6967.Peer Reviewe

Inhibition of cAMP Responsive Element Binding Protein in Striatal Neurons Enhances Approach and Avoidance Responses toward Morphine- and Morphine Withdrawal-related Cues

To investigate the role of cAMP responsive element binding protein (CREB)-dependent gene expression in morphine induced behaviors, we examined bitransgenic mice expressing a dominant and strong inhibitor of the CREB family of transcription factors, A-CREB, in striatal neurons in a regulatable manner. The expression of A-CREB in the striatum enhanced both morphine-induced conditioned place preference and morphine withdrawal-induced conditioned place avoidance. Our experiments thereby support a role for CREB in striatal neurons regulating approach and avoidance responses toward drug-related cues

Inhibition of cAMP response element-binding protein reduces neuronal excitability and plasticity, and triggers neurodegeneration

The cAMP-responsive element-binding protein (CREB) pathway has been involved in 2 major cascades of gene expression regulating neuronal function. The first one presents CREB as a critical component of the molecular switch that controls long-lasting forms of neuronal plasticity and learning. The second one relates CREB to neuronal survival and protection. To investigate the role of CREB-dependent gene expression in neuronal plasticity and survival in vivo, we generated bitransgenic mice expressing A-CREB, an artificial peptide with strong and broad inhibitory effect on the CREB family, in forebrain neurons in a regulatable manner. The expression of A-CREB in hippocampal neurons impaired L-LTP, reduced intrinsic excitability and the susceptibility to induced seizures, and altered both basal and activity-driven gene expression. In the long-term, the chronic inhibition of CREB function caused severe loss of neurons in the CA1 subfield as well as in other brain regions. Our experiments confirmed previous findings in CREB-deficient mutants and revealed new aspects of CREB-dependent gene expression in the hippocampus supporting a dual role for CREB-dependent gene expression regulating intrinsic and synaptic plasticity and promoting neuronal survival.European Commission grants (MEXT-CT-2003-509550 and MIRG-CT2005-016343), Spanish MEC Grants (BFU2005-00286 and CSD2007-00023), and grants from Fundació La Marató de TV3 and Fundacioón Ramón Areces supported research at A.B.’s lab.Peer Reviewe

Hunting for synaptic tagging and capture in memory formation

This work was supported by grants from Generalitat Valenciana BFPI06/ 316 (J.V.), EuskoJaurlaritza BFI06.30(E.B.), European Commission MEXTCT-2003-509550(D.J.), and Fundacion la Marato´TV3063510(J.P.L.A.).Peer reviewe

Enhanced CREB-dependent gene expression increases the excitability of neurons in the basal amygdala and primes the consolidation of contextual and cued fear memory

Regulated expression of a constitutively active form of cAMP response element-binding protein (CREB), VP16-CREB, lowers the threshold for the late phase of long-term potentiation in the Schaffer collateral pathway in a de novo gene expression-independent manner, and increases the excitability and reduces afterhyperpolarization of neurons at the amygdala and the hippocampus. We explore the consequences of these changes on the consolidation of fear conditioning and find that the expression of VP16-CREB can bypass the requirement for de novo gene expression associated with long- term memory formation, suggesting that CREB-dependent gene expression is sufficient for fear memory consolidation. © 2009 Cold Spring Harbor Laboratory Press.J.V. holds a fellowship from the Generalitat Valenciana (BFPI06/316). This work was supported by European Commission grant MEXT-CT-2003-509550, Spanish MEC grants BFU2005-00286 and CSD2007-00023, Generalitat Valenciana grant AP-046/08, and grants from Fundació La Marató de TV3 and Fundación Ramón Areces.Peer Reviewe

Identification of sterile cytoplasm (CMS) in maize by using specific mtDNA primers

Thirty sources of cytoplasmic male sterility (CMS) from Maize Gene Bank "Zemun Polje", distributed among Yugoslav OP varieties, have been tested for the presence of particular type of cytoplasm by a single seed multiplex PCR approach with specific primer pairs for T, C and S type cytoplasm. Combination of three pairs of primers in a single PCR reaction, corresponding to the chimeric regions of mtDNA sequences specific for each type of CMS, allowed reliable identification of the major CMS types. Dominant presence of S type cytoplasm was detected. For sources where there is no clear identification of the type of CMS (absence of the PCR band) there is a reasonable doubt that it could be a new, yet unidentified type of CMS.Trideset izvora citoplazmatične muške sterilnosti (CMS) u okviru lokalnih populacija iz Banke gena Instituta za kukuruz "Zemun Polje" je testirano na prisustvo odgovarajućeg tipa citoplazme multipleks PCR metodom, korišćenjem specifičnih prajmera za T, C i S citoplazmu. Kombinovanje tri para prajmera u jednoj PCR reakciji, koji odgovaraju himernim regionima mitohondrijalnih DNK sekvenci specifičnih za svaki tip citoplazme, omogućilo je pouzdanu identifikaciju glavnih tipova sterilne citoplazme. Detektovano je dominantno prisustvo S tipa citoplazme. Za izvore sterilnosti kod kojih nije identifikovan tip sterilne citoplazme (odsustvo PCR trake) postoji realna sumnja da se radi o novim, neidentifikovanim tipovima citoplazmatične muške sterilnosti

cAMP response element-binding protein-mediated gene expression increases the intrinsic excitability of CA1 pyramidal neurons

To investigate the role of CREB-mediated gene expression on the excitability of CA1 pyramidal neurons, we obtained intracellular recordings from pyramidal neurons of transgenic mice expressing a constitutively active form of CREB, VP16–CREB, in a regulated and restricted manner. We found that transgene expression increased the neuronal excitability and inhibited the slow and medium afterhyperpolarization currents. These changes may contribute to the reduced threshold for LTP observed in these mice. When strong transgene expression was turned on for prolonged period of time, these mice also showed a significant loss of hippocampal neurons and sporadic epileptic seizures. These deleterious effects were dose dependent and could be halted, but not reversed by turning off transgene expression. Our experiments reveal a new role for hippocampal CREB-mediated gene expression, identify the slow afterhyperpolarization as a primary target of CREB action, provide a new mouse model to investigate temporal lobe epilepsy and associated neurodegeneration, and illustrate the risks of cell death associated to a sustained manipulation of this pathway. As a result, our study has important implications for both the understanding of the cellular bases of learning and memory and the consideration of therapies targeted to the CREB pathway.A.B., M.L.d.A., D.J., and R.O. are supported by European Commission Grants MEXT-CT-2003-509550 and MIRG-CT-2005-016343, Spanish Ministerio de Educación y Ciencia Grants BFU2005-00286 and SAF2005-24584-E, and Generalitat Valenciana Grant ACOMP06/061. E.R.K. and J.M.A. are supported by Howard Hughes Medical Institute and the Kavli Institute for Brain Sciences.Peer reviewe