NCT04122742

Diagnosis of RSTS: Identification of the Acetylation Profiles as Epigenetic Markers for Assessing Causality of CREBBP and EP300 Variants.

• Status: Unknown
• Phase: —
• Study type: Observational
• Enrollment: 154 (estimated)
• Sponsor: University Hospital, Bordeaux · Academic / Other
• Sex: All
• Age: 2 Years
• Healthy volunteers: Not accepted

Summary

Rubinstein-Taybi syndrome (RSTS) is a rare and severe congenital developmental disorder characterized by congenital anomalies and intellectual disability with a long term memory deficit. The main challenge is to improve the intellectual and memory efficiency of these patients. CREBBP and EP300 are the two genes known to cause RSTS. Both paralogs play a major role in chromatin remodeling and encode for transcriptional co-activators interacting with many proteins. The aim of this pilot study is to characterize the histone acetylation profiles in order to identify specific acetylation markers during normal and pathological neuronal differentiation of cortical and pyramidal neurons in RSTS.

Detailed description

CREBBP and EP300 are the two paralog genes associated with RSTS determinism and code for CBP and p300, respectively. These proteins are transcriptional coactivators that possess a catalytic lysine acetyl transferase (KAT) domain involved in the acetylation of lysine residues of histones but also other proteins. CBP and p300 promote transcription by creating a chromatin environment that is favorable for gene expression and by linking different transcription factors to each other. They thus orchestrate the regulation of the transcription machinery, from the basal promoter to the enhancers of the target genes. RSTS is considered a genetic model of neurodevelopmental anomaly with an epigenetic component. Histone acetylation is one of the major post-translational modifications (PTMs) of these proteins that provide for the formation and control of chromatin structure. When differentiating embryonic cells, this modification plays a key role in transcriptional activation. The mouse models of RSTS have made the link between the modulation of histone acetylation and the formation of memory by showing their key role in neuronal plasticity. However no data exists on the acetylation of histones in the neurons of RSTS patients. Furthermore, in humans, the molecular pathways impacted by these alterations during neurodevelopment are not specified, especially in the pyramidal neurons which are the precursors of hippocampal neurons involved in the encoding and storage of memory. In RSTS a loss of CBP function results in a deficit in KAT activity, which is responsible for altering histone acetylation, leading to inappropriate changes in chromatin structure. The consequence of a mutation is a result of a deregulation of the activity of genes involved in development. No neuronal level studies are currently available on the functional link between histone acetylation and deregulated genes in the RSTS. In this project, investigators will identify target genes whose epigenetic regulation is mediated by histone acetylation. More specifically, the study will focus on chromatin dynamics during normal and pathological neuronal differentiation of cortical and pyramidal neurons. Investigators will determine among the CBP-dependent histone markers, those that are modified in RSTS patients cells and the loci they control. In parallel, investigators will define genes whose neuronal expression is altered in RSTS patients. The integration of all these data will allow us to specify which genes are deregulated during neuronal differentiation as a consequence of CBP lysine acetyltransferase function loss.

Conditions

• Rubinstein-Taybi Syndrome

Interventions

Type	Name	Description
PROCEDURE	skin biopsy for the primary fibroblast culture and a 15 ml blood sample (3 unnamed samples of 5ml) in each of the 4 SRT patients included.	Performed with a 3 mm diameter punch under local anesthesia. The procedure can be done in a consultation office respecting a strict asepsis.
OTHER	Generation of Induced Pluripotent Stem Cells (iPSC) from fibroblasts obtained by skin biopsy	induced Pluripotent Stem Cells (iPSC) production of patients with CREBBP mutation and differentiation into cortical neurons and pyramidal neurons
OTHER	Histone acetylation profiles of cells of SRT patients with CREBBP mutations	Study of acetylome by liquid chromatography coupled with tandem mass spectrometry (LC-MS / MS) Validation of specific acetylation targets by ChIP-Sequencing
OTHER	Functional involvement of identified epigenetic alterations	Transcriptome analysis with RNA-Seq Generation of isogenic iPSC clones by correction of CREBBP mutations in SRT patients by CrispR-Cas9.
BIOLOGICAL	Culture of lymphoblastoid line from blood sample	Achievement of a ficoll Culture of lymphoblasts and conservation Establishment of lymphoblastoid line and conservation

Timeline

• Start date: 2019-10-08
• Primary completion: 2025-10-01
• Completion: 2025-10-01
• First posted: 2019-10-10
• Last updated: 2024-01-17

Locations

1 site across 1 country: France