Signaling Networks Evoking Gene Expression Responsible for Formation of Memory

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Long-term memory formation is related to multiple signal transduction pathways, delivering information from synapses to the neuron nucleus to alter gene expression pattern, cAMP-PKA-CREB pathway is one of the most widely studied signaling network. However, multiplicity of structural and functional changes occurring during long-term memory formation, e.g. late LTP, synapse consolidation, new synapse formations and de novo protein synthesis, cannot be explained only via limited number of signaling mechanisms. Hence, this project is design to determine the key regulatory proteins involved in signal transduction from synapses towards the nucleus during the memory formation process.

 

In our Laboratory

Findings

The project incorporates behavioral, proteomic, genomic, electrophysiological study together with in silico analysis and classic biochemistry and immunohistochemistry experiments. This research is a multistep project. At the current step, we identified protein-protein interaction networks of multiple signal transduction process associated with long-term spatial memory using eight radial arm maze reference memory paradigm. We detected 1592 proteins, which exhibited a complex picture of expression changes during spatial memory formation. Variable linear decomposition reduced significantly data dimensionality and enriched three principal factors responsible for variance of memory-related protein levels at 1) the initial phase of memory acquisition (165 proteins), 2) during the steep learning improvement (148 proteins), and 3) the final phase of the learning curve (123 proteins). Gene ontology and signaling pathways analysis revealed a clear correlation between memory improvement and learning phase-curbed expression profiles of proteins belonging to specific functional categories. We found differential enrichment of a) neurotrophic factors signaling pathways, proteins regulating synaptic transmission, and actin microfilament during the first day of the learning curve; b) transcription and translation machinery, protein trafficking, enhancement of metabolic activity, and Wnt signaling pathway during the steep phase of memory formation; and c) cytoskeleton organization proteins.  Taken together, this study clearly demonstrates dynamic assembly and disassembly of protein-protein interaction networks depending on the stage of memory formation engrams.

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Plans

At the current stage, we investigate the combinatorial role of kinases and phosphatases using radial arm maze behavioral paradigms for the spatial memory as the model system. Proteomic study designed to this project focuses to elucidate alteration pattern of their post-translational modification at synaptic level in animals trained by the behavioral paradigm. Genomic part of the project deals with the gene expression pattern change during the process of learning for the exploited behavioral paradigm. Upon finalization of harvesting and processing of high-throughput analysis data, wide in silico analysis will be conducted to link signal transductions with the gene expression pattern and find master key regulators for the signaling. The discovered key proteins will be further tested for functional significance.

Functional part of the project transform into the standalone projects of study of selected key regulators and their interaction networks as for projects of AKT and Abl kinases. Using pharmacological and gene expression modifications tools, selected key regulators and their network domains will be studied for elucidation of their impact on memory formation and synaptic plasticity, using optogenetic, electrophysiological and behavioral tools and validating on biochemical and morphological levels.

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Projects

1. Investigation of the integrative role protein-protein interaction network associated with serine/threonine phosphorylation in long-term memory formation and long-term synaptic plasticity (Ph.D or Post-Doctoral position, S001)

2. Investigation of the integrative role protein-protein interaction network associated with tyrosine phosphorylation in long-term memory formation and long-term synaptic plasticity (Ph.D or Post-Doctoral position, S002)

3. Investigation of the role of key regulator specific network domains on gene expression pattern associated with long-term memory (Ph.D or Post-Doctoral position, S003)

 

Related References from our Lab

• Borovok N, Nesher E, Levin Y, Reichenstein M,  Pinhasov A, Michaelevski I, Dynamics of hippocampal protein expression during long-term spatial memory formation.  Molecular and cellular proteomics 2016 Feb; 15(2):523-41. doi: 10.1074/mcp.M115.051318.

• Borovok N, Nesher E, Levin Y, Reichenstein M,  Pinhasov A, Michaelevski I, Dynamics of striatum protein expression during long-term spatial memory formation.  Manuscript in preparation