Transcriptome and acetylome profiling identify crucial steps of neuronal differentiation in Rubinstein-Taybi syndrome

Rubinstein-Taybi syndrome (RTS) is a rare and severe genetic developmental disorder characterized by multiple congenital anomalies and intellectual disability. CREBBP and EP300, the two genes known to cause RTS encode transcriptional coactivators with a catalytic lysine acetyltransferase (KAT) activity. Loss of CBP or p300 function results in a deficit in protein acetylation, in particular at histones. In RTS, nothing is known on the consequences of the loss of histone acetylation on the transcriptomic profiles during neuronal differentiation. To address this question, we differentiated induced pluripotent stem cells from RTS patients carrying a recurrent CREBBP mutation that inactivates the KAT domain into cortical and pyramidal neurons. By comparing their acetylome and their transcriptome at different neuronal differentiation timepoints, we identified 25 specific acetylated histone residues altered in RTS. We also identified the transition between neural progenitors and immature neurons as a critical step of the differentiation process, with a delayed neuronal maturation in RTS. Overall design: To address our objectives of studying the consequences of acetylation alteration during neuronal differentiation, the first phase of this work will be the generation of iPSCs-derived neurons from fibroblasts of RSTS patients carrying the same CREBBP mutation. The second phase will concern the characterization of acetylation profiles in cells from patients in comparison with control cases. This second step will allow us to characterize the proteins whose acetylation profile is specifically altered in RSTS and the associated biological pathways. In the 3rd phase of the work, we will study the functional impact of these epigenetic alterations on neuronal differentiation by analysing the transcriptome by RNA-Seq.