Characterizing the gene regulatory circuitry of ST18 underlying neurogenesis

• Applicant: Dr. Angela Garding
• Subject Area: Developmental Neurobiology ; Developmental Biology
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 285949736

Specification of neuronal fate during development relies on a precisely controlled gene expression program. Despite progress, the repertoire of transcription factors involved in transcriptional reprogramming underlying neurogenesis remains largely unexplored. Using extensive computational biology tools in combination with genomewide transcriptome analysis of multiple tissues from all three lineages during embryonic development, we have identified several novel potential transcriptional regulators of neurogenesis. We further show that the in vivo knockdown of one such candidate, St18, led to defective neurogenesis during development, suggesting its functional importance. Genomewide transcriptome analysis of cortical cells following depletion of St18 uncovered its dominant function as a transcriptional repressor during onset of neurogenesis to ensure silencing of genes that would otherwise impair early steps of neurogenesis including cell cycle regulators, adhesion and non-neuronal lineage genes. Based on these findings we want to achieve the following research aims within the proposed project: By applying epigenomics approaches in combination with CRISPR-mediated endogenous tagging of St18 locus, we will comprehensively identify the genomic targets of this protein and its dynamics during neuronal differentiation (Aim 1). We will next employ IP-mass spectrometry to identify proteins interacting with St18 and explore the significance of this physical association for its gene regulatory function (Aim 2). Using the datasets on genomic targets (from Aim 1) and protein partners (from Aim 2), we will use mathematical modeling to outline the gene regulatory circuitry of St18 (Aim 3.1). Using perturbation experiments, we will then test the functional relevance of key nodes in the model derived in Aim 3.1 for St18 function (Aim 3.2). We will also employ time-lapse imaging in organotypic slice cultures of St18 depleted brains to track the kinetics of phenotypic alteration. In complementation with rescue experiments using various truncated versions of St18 we will reveal domains that are critically required for its function during neurogenesis (Aim 4). Altogether, these findings will generate a mechanistic model of how St18 contributes to the transcriptional program underlying neurogenesis.

• DFG Programme: Research Grants