Astrocytes comprise one of the main cell types in the central nervous system (CNS), and it is now recognized that they have important roles in ensuring proper development and homeostasis of the CNS, with astrocyte dysfunction contributing to all major neurological disorders. Recent studies have shown that these cells undergo dramatic transcriptional changes in response to neuron-derived stimuli. However, what are the astrocyte-specific mechanisms that regulate these changes are still largely unknown. Here, this issue will be tackled using state-of-the art functional genomic approaches to generate a comprehensive map of the astrocyte-specific regulatory elements (with a focus on enhancers) and transcription factors that govern stimuli-induced gene expression changes. This will provide unique and original insights into the mechanisms that control stimuli-induced gene expression in non-neuronal CNS cells, with potential implications for the understanding of several neuropathologies.
Formation of new synapses, and alteration of the strength and stability of existing synapses are regarded as the main cellular basis for memory and long-term behavioral adaptations. Neuronal activity-regulated gene expression plays a crucial role in synaptic development and function, and its deregulation gives rise to various nervous system disorders. Knowledge about the regulatory mechanisms of activity-dependent gene expression is important both for understanding of nervous system function and for finding new drug targets. The aim of this project is to study the molecular mechanisms of neuronal activity-regulated gene expression, including transcription, translation and posttranslational modifications, in the nervous system health and disease. The studies are focused on two genes, the neurotrophin BDNF and the basic helix-loop-helix transcription factor TCF4.
"Pitt-Hopkins syndrome is a cognitive functional disorder, caused by a de novo genetic mutation of one allele of the transcription factor 4 (TCF4) gene. It has been reported that postnatal restoration of TCF functions in Pitt-Hopkins syndrome animal model (partially) rescues the phenotype, indicating that therapeutic approaches increasing TCF4 levels or activity might also help patients. It has also been reported that inhibiting histone deacetylase activity increases TCF4 transcriptional activity and rescues memory deficiencies associated with TCF4 haploinsufficiency in a mouse model. These effects are likely conveyed by some TCF4 co-repressor, such as ETO/RUNX1T1 recruiting HDACs. However, HDAC inhibitors have a very broad effect on the cellular transcription and can cause various side-effects.
Here, we hypothesize that by modulating the activity of specific TCF4 co-activators or co-repressors or their interaction with TCF4 could increase TCF4-dependent transcription, thus alleviating the symptoms of Pitt-Hopkins syndrome and have less side effects for the patients. To this end, we pursue to thoroughly identify the co-regulators participating in TCF4-dependent transcription, and to find means to modulate their activity. The specific aims are as follows: (1) Identify the co-regulatory proteins of different TCF4 protein isoforms. (2) Determine the mechanism of action and the interacting regions between TCF4 and co-regulatory proteins. (3) Develop means to modulate the transcriptional activity or binding of the TCF4 co-regulatory proteins."