Poster Sessions AP05: Neuronal and Glial Cell Biology

Acetylcholinesterase (AChE) is classically known for terminating cholinergic transmission, however, increasing evidence shows that the biological function of AChE is not limited to this role. Interestingly, the AChE gene is either amplified, mutated and/or aberrantly expressed by cells in a variety of human tumors despite the fact that AChE is not present in their normal counterparts. Studies from our laboratory and others have shown that AChE is transiently expressed during normal neural development when cells are invariably engaged in intense growth and movement. Together, these observations support the idea that AChE may play a role in tumorigenesis, however, this hypothesis has not been tested before. In support of this idea, we have found that neuroblastoma cells genetically engineered to over-express AChE developed tumors in vivo at a notably greater rate compared with transfection controls. Tumor cells were implanted into the brains of irradiated Fischer rats and following a 10-day survival period, macroscopic examination revealed that the tumor mass generated from the AChE over-expressing cells was six-fold greater than transfection controls. Moreover, histochemical and Western blot analyses of two human glioma cell lines revealed that the different levels of AChE expression in these cells directly correlated with their proliferation rates. These studies showed that the high AChE-expressing cells divided at a 50% greater rate than the low AChE-expressing cells. Interestingly, the high AChE-expressing cells also exhibited increased MAPK phosphorylation, a key step in the regulation of cell growth. These findings together with the consistent observation that AChE is misexpressed in human tumors, and the fact that AChE levels are up-regulated during normal development, support the idea that AChE plays a role in tumor cell growth.     

Poster Sessions

Approval of an anti-CD20 chimeric monoclonal antibody, rituximab, has revolutionized cancer treatment and also validated CD20 targeting for providing benefit and improvement of overall response rate in B cell malignancies. Although many patients have benefited from the treatment of rituximab, there are still significant numbers of patients who are refractory or develop resistance to the treatment. Here we discuss pre-clinically well-defined potential mechanisms of action for rituximab and review the ways next generation anti-CD20 monoclonal antibodies can potentially exploit them to further enhance the treatment of B cell malignancies. Although the relative importance of each of these mechanism remains to be established in the clinic, well-designed clinical trials will help to define the efficacy and understanding of which effector activity of modified next generation anti-CD20 mAb will be important in the treatment of B-cell malignancies.     

Poster Sessions AP01: Gene Expression and Regulation. Regulation of gene expression during the development of cortico‐thalamic connection in rat

The formation of Cortico‐Thalamic projections requires the precise spatial and temporal expression of proteins that are involved in the different stages of synaptogenesis. We reasoned that the underlying molecular mechanism of this process is the differential expression of genes that code for stage specific proteins. Our research objective was to identify the differential expressed mRNAs during the main stages of synapses formation, which starts at embryonic day 12 (E12) and finishes on the first postnatal days in the rat. We approach this problem using Differential Display technique on three distinct ages of rat cerebral cortex that were: E13, E18 and postnatal day 0 (P0). We found 80 differential bands using 54 random primers and 18 of them were cloned and sequenced. The sequence analysis showed among others, a cDNA fragment highly homologous with the human A Kinase Anchoring Protein 450/350 also called CG‐NAP. We found that this cDNA fragment homologous to AKAP was up regulated at E15 when cortical cells are undergoing active axogenesis. The expression pattern of this cDNA was confirmed by Real Time PCR. Our findings suggest a possible function for AKAP 450 in the regulation of the state of phosphorylation of centrosomal components during the initial stages of synapses formation during the establishment of Cortico‐Thalamic connection.     

Poster Sessions BP05: Neuroimmunology

Experimental allergic encephalomyelitis (EAE) is the animal model for Multiple Sclerosis (MS), the chronic autoimmune disease of the central nervous system (CNS). Activation of NF-κB requires the activity of IkB kinase (IKK) complex containing (IKKa and IKKb) and the regulatory protein NEMO (NF-κB essential modifier). Recently it has been shown that peptides corresponding to the NEMO-binding domain (NBD) of IKKa or IKKb specifically inhibit the induction of NF-κB activation without inhibiting the basal NF-κB activity. The present study underlines the importance of cell-permeable NBD peptides in inhibiting the disease process of adoptively-transferred EAE in female SJL/J mice. Immunocytochemical analysis of spinal cords of EAE mice showed that there was marked induction of NF-κB activation as evidenced by enhanced p65 (the RelA subunit of NF-κB) expression compared to that of control mice. Double-labelling analysis of p65 and cell-specific markers showed that p65 was mainly expressed by astrocytes, microglia and infiltrating macrophages. Next we examined the effect of NBD peptides on the disease process of EAE. Interestingly, clinical symptoms of EAE were much lower in mice receiving wild type NBD peptides. In contrast, mutated NBD peptides had no effect on the clinical symptoms of EAE. Taken together, our results support the conclusion that activation of NF-κB participates in the disease process of EAE and that inhibitors of NF-κB activation may ameliorate the neuroinflammatory disease process in MS patients.
Acknowledgements:   This study was supported by NIH grants (NS39940 and AG19487.