Depletion of the Fragile X Mental Retardation Protein in Embryonic Stem Cells Alters the Kinetics of Neurogenesis.
Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and a leading cause of autism. FXS is due to the silencing of the Fragile X Mental Retardation Protein (FMRP), an RNA binding protein mainly involved in translational control, dendritic spine morphology and synaptic plasticity. Despite extensive studies, there is currently no cure for FXS. With the purpose to decipher the initial molecular events leading to this pathology, we developed a stem-cell-based disease model by knocking-down the expression of Fmr1 in mouse embryonic stem cells (ESCs). Repressing FMRP in ESCs increased the expression of amyloid precursor protein (APP) and Ascl1. When inducing neuronal differentiation, βIII-tubulin, p27kip1, NeuN, and NeuroD1 were upregulated, leading to an accelerated neuronal differentiation that was partially compensated at later stages. Interestingly, we observed that neurogenesis is also accelerated in the embryonic brain of Fmr1-knockout mice, indicating that our cellular model recapitulates the molecular alterations present in vivo. Importantly, we rescued the main phenotype of the Fmr1 knockdown cell line, not only by reintroducing FMRP but also by pharmacologically targeting APP processing, showing the role of this protein in the pathophysiology of FXS during the earliest steps of neurogenesis. Our work allows to define an early therapeutic window but also to identify more effective molecules for treating this disorder. Stem Cells 2017;35:374-385.
Université Côte d'Azur, Nice, France.|CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne Sophia-Antipolis, France.|CNRS, LIA « NEOGENEX », Valbonne Sophia-Antipolis, France.
Olfa
O
Khalfallah
Université Côte d'Azur, Nice, France.|CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne Sophia-Antipolis, France.|CNRS, LIA « NEOGENEX », Valbonne Sophia-Antipolis, France.
Marielle
M
Jarjat
Université Côte d'Azur, Nice, France.|CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne Sophia-Antipolis, France.
Laetitia
L
Davidovic
Université Côte d'Azur, Nice, France.|CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne Sophia-Antipolis, France.
Nicolas
N
Nottet
Université Côte d'Azur, Nice, France.|CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne Sophia-Antipolis, France.
Sandrine
S
Cestèle
Université Côte d'Azur, Nice, France.|CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne Sophia-Antipolis, France.
Massimo
M
Mantegazza
Université Côte d'Azur, Nice, France.|CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne Sophia-Antipolis, France.|CNRS, LIA « NEOGENEX », Valbonne Sophia-Antipolis, France.
Barbara
B
Bardoni
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D048430:Cell Shape / Q000235:genetics; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D007700:Kinetics; D051379:Mice; D018345:Mice, Knockout; D000066450:Mouse Embryonic Stem Cells / Q000378:metabolism*; D055495:Neurogenesis / Q000235:genetics; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics
D051792:Basic Helix-Loop-Helix Proteins; D051860:Fragile X Messenger Ribonucleoprotein 1; D034741:RNA, Small Interfering; C499317:Ascl1 protein, mouse
Autism; Embryonic stem cells; Fragile X syndrome; Intellectual disability; Neurogenesis; Therapeutic window