Multiple splice patterns of cyclic AMP response element-binding protein mRNA in the central nervous system of the rat

CREB expression in the brains of two closely related parasitic wasp species that differ in long-term memory formation

The cAMP/PKA signalling pathway and transcription factor cAMP response element-binding protein (CREB) play key roles in long-term memory (LTM) formation. We used two closely related parasitic wasp species, Cotesia glomerata and Cotesia rubecula, which were previously shown to be different in LTM formation, and sequenced at least nine different CREB transcripts in both wasp species. The splicing patterns, functional domains and amino acid sequences were similar to those found in the CREB genes of other organisms. The predicted amino acid sequences of the CREB isoforms were identical in both wasp species. Using real-time quantitative PCR we found that two low abundant CREB transcripts are differentially expressed in the two wasps, whereas the expression levels of high abundant transcripts are similar.

Striatal glutamatergic mechanisms and extrapyramidal movement disorders

The nonphysiologic stimulation of striatal dopaminergic receptors, as a result of disease- or drug-related denervation or intermittent excitation, triggers adaptive responses in the basal ganglia which contribute to the appearance of parkinsonian symptoms and later to the dyskinesias and other alterations in motor response associated with dopaminergic therapy. Current evidence suggests that these altered responses involve activation of signal transduction cascades in striatal medium spiny neurons linking dopaminergic to coexpressed ionotropic glutamatergic receptors of the N-methyl-D-aspartate (NMDA) and Alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) classes. These intraneuronal signaling pathways appear capable of modifying the phosphorylation state of NMDA and AMPA receptor subunits; resultant sensitization enhances cortical glutamatergic input which in turn modifies striatal output in ways that compromise motor behavior. The regulation of these spiny neuron glutamate receptors can also be affected by the activation state of coexpressed nondopaminergic receptors as well as by changes associated with Huntington's disease. These observations lend new insight into molecular mechanisms contributing to the integration of synaptic inputs to spiny neurons. They also suggest novel approaches to the pharmacotherapy of extrapyramidal motor dysfunction.

Striatal dopamine- and glutamate-mediated dysregulation in experimental parkinsonism

Characteristic changes involving interactions between dopamine and glutamate in striatal medium spiny neurons now appear to contribute to symptom production in Parkinson's disease (PD). The balance between kinase and phosphatase signaling modifies the phosphorylation state of glutamate receptors and thus their synaptic strength. Sensitization of spiny-neuron NMDA and AMPA receptors alters cortical glutamatergic input to the striatum and modifies striatal GABAergic output, and thus motor function. Conceivably, the pharmacological targeting of spiny-neuron mechanisms modified in PD will provide a safer and more effective therapy.

Alternative exon splicing of cyclic AMP response element-binding protein in peripheral sensory and sympathetic ganglia of the rat

Alternative splicing patterns of cyclic AMP response element-binding protein (CREB) in dorsal root ganglia, lumbar sympathetic ganglia and several peripheral tissues of the rat have been investigated by an exon-flanking polymerase chain reaction strategy. A series of RT-PCR with primer pairs flanking all possible alternative splicing sites (corresponding to a genomic region with at least one full exon and two flanking introns) has revealed multiple tissue specific splice variants. These include some novel transcripts that lack the phosphorylation site and part of the leucine zipper region which is crucial for dimerization and DNA binding. Some isoforms previously reported as testis-specific were also detected in rat peripheral ganglia and other tissues. Notably, splicing patterns are specific for some regions. Some of the splice variants indicate inhibitory functions due to lacking phosphorylation sites or partially missing DNA-binding or leucine zipper domains. These findings suggest a complex expression and functional regulation of CREB in peripheral tissues including dorsal root and sympathetic ganglia.