Neurodevelopmental disorders (NDDs), namely intellectual disability and autism spectrum disorder, are common conditions, affecting up to 3% of the population. Chromatin regulators, a group of genes encoding proteins that control the way the rest of the genome is opened up and “read” by the cellular machinery, are highly implicated in NDDs. BAF swi/snf complexes are important chromatin regulators in development and disease. These large multiprotein complexes assemble different subunits in cell-type and developmental stage-specific combinations. They are some of the most frequently mutated genes in NDDs, and almost all complex subunits have been impacted in these disorders. BAF complexes have a fundamental role in neurogenesis: in mouse, they direct the transition from neural progenitor to post-mitotic neurons, by “switching” subunit homologous counterparts. Because there are key differences in human neurogenesis that are not recapitulated by animal models, namely size, complexity and differences in temporal development and proportions of cell types, this project aims to investigate the transition between complex assemblies in human development. Through the following aims, it will use cutting-edge molecular, proteomic and cell biology methods (supervised by Dias) and single-particle cryo-electron microscopy (cryo-EM) (supervised by Bergeron and Atherton) to investigate BAF swi/snf complexes in neurodevelopment.
Aim 1: Establish a human in vitro model of progenitor to neuron transition in human iPSCs.
The student will use microscopy, transcriptomic and proteomic methods to define enriched populations of progenitors and neurons.
Aim 2: Structural characterisation of BAF subunits at different stages of neurodevelopment.
Using the optimised protocol, the student will use a multidisciplinary approach for identification of time-specific subunits: structural determination of immunoprecipitated complexes by cryo-EM; orthogonal validation approaches will be used, namely mass spectroscopy and density sedimentation and western blot.
Aim 3: Investigate the requirement of different “switch” subunits for normal neural differentiation using CRISPR/Cas9.
Chromatin remodelling complexes in human brain development
Representative Publications
• Pioneer factor ASCL1 cooperates with the mSWI/SNF complex at distal regulatory elements to regulate human neural differentiation. Păun O, Tan YX, Patel H, Strohbuecker S, Ghanate A, Cobolli-Gigli C, Llorian Sopena M, Gerontogianni L, Goldstone R, Ang SL, Guillemot F & Dias C. Genes Dev. 2023 Mar 1;37(5-6):218-242. doi: 10.1101/gad.350269.122. • Generation of an iPSC line (CRICKi001-A) from an individual with a germline SMARCA4 missense mutation and autism spectrum disorder. Devito LG, Healy L, Mohammed S, Guillemot F, Dias C. Stem Cell Res. 2021 Mar 20;53:102304. DOI: 10.1016/j.scr.2021.102304. • BCL11A haploinsufficiency causes an intellectual disability syndrome and dysregulates transcription. Dias C, Busquetes Estruch S, Graham SA, et al. Am J Hum Genet. 2016, Aug 4;99(2):253-274. DOI: 10.1016/j.ajhg.2016.05.030.
• The structure of the bacterial DNA segregation ATPase filament reveals the conformational plasticity of ParA upon DNA binding. Parker AV, Mann D, Tzokov SB, Hwang LC, Bergeron JRC. Nat Commun. 2021 Aug 27;12(1):5166. doi: 10.1038/s41467-021-25429-2. • Single-particle cryo-EM analysis of the shell architecture and internal organization of an intact α-carboxysome. Structure. Evans SL, Al-Hazeem MMJ, Mann D, Smetacek N, Beavil AJ, Sun Y, Chen T, Dykes GF, Liu LN, Bergeron JRC. 2023 Jun 1;31(6):677-688.e4. doi: 10.1016/j.str.2023.03.008. • Structure and lipid dynamics in the maintenance of lipid asymmetry inner membrane complex of A. baumannii. Mann D, Fan J, Somboon K, Farrell DP, Muenks A, Tzokov SB, DiMaio F, Khalid S, Miller SI, Bergeron JRC. Commun Biol. 2021 Jun 29;4(1):817. doi: 10.1038/s42003-021-02318-4.