Project description:Deregulation of neuro-developmental genes and primary cilium cytoskeleton anomalies in iPSC retinal sheets from human syndromic ciliopathies
Project description:Centriolar satellites are an array of membrane-less granules that localize and move around the vertebrate centrosome/cilium complex. They have recently emerged as key regulators of the biogenesis and function of the centrosome/cilium-complex and their mutations are linked to ciliopathies. Although centriolar satellites are ubiquitous structures of the vertebrate cells, their precise function and molecular mechanism of action in different cell types remain poorly understood. Here, we generated kidney and retinal epithelial cells that lack centriolar satellites by genetically ablating their scaffolding protein PCM1 and investigated the cellular and molecular consequences of satellite loss in cells. We showed that centriolar satellites are required for cilium assembly, regulation of ciliary content, timely response to Hedgehog signals and three- dimensional epithelial cell organization, but not for cell proliferation, cell cycle progression and centriole duplication. Importantly, the requirement for centriolar satellites in cilium assembly varied between retinal and kidney epithelial cells and we identified the differences in the efficiency of targeting key ciliogenesis factors to the centrosome including Mib1 and Talpid3 as the likely molecular basis for this phenotypic variability. Quantitative global transcriptomic and proteomic profiling of satellite-less cells showed that loss of centriolar satellites does not lead to a major transcriptional response, but leads to a significant rearrangement of the global proteome. Together, our findings identify important roles for centriolar satellites in key cilium-related cellular processes through regulating the proteostasis and centrosomal/ciliary targeting of proteins and provide insight into the disease mechanisms of ciliopathies.
Project description:We used single cell RNA sequencing to investigate the cell diversity in our in vitro differentiation from iPSC to Retinal sheets culture and the development of our culture.
Project description:Three-dimensional retinal organoids (3D-retinas) are a promising graft source for transplantation therapy. We previously developed self-organizing culture for 3D-retina generation from human induced pluripotent stem cells (hiPSCs). Toward clinical applications on hPSC-derived retinal sheets, the establishment of a quality control (QC) strategy for 3D-retinas and dissected retinal sheets has remained a major challenge. We performed a microarray analysis for retinal tissue and off-target tissue to identify the major off-target tissue in hiPSC-culture.
Project description:Transforming Growth Factor-Beta-Activated Kinase 1 (TAK1/MAP3K7), along with its upstream regulators TAK1-Binding Protein 2 (TAB2) and the catalytic alpha-subunit of Protein Kinase A (PKA-Cα/PRKACA), has been identified as a pivotal player in regulation of developmental processes. Haploinsufficiency of TAB2 causes Congenital Heart Disease (CHD) and rare variants in PKA-Cα and TAK1 cause cardioacrofacial dysplasia (CAFD), and Frontometaphyseal Dysplasia (FMD) and cardiospondylocarpofacial syndrome (CSCFS), respectively, rare multisystem syndromes, where CHD may appear in the clinical spectrum. We hypothesized that TAK1 plays a significant role in heart development and CHD and addressed this by genetic analysis in CHD patient cohorts and experiments in cell and animal models. Exome sequencing data from 1,471 CHD patients with extracardiac anomalies (syndromic CHD, sCHD), 2,405 patients with nonsyndromic CHD (nsCHD) and 45,082 controls showed increased burden of rare TAB2 and TAK1 variants in sCHD, but not in nsCHD. Detailed characterization of tak1-/- and tab2-/- zebrafish mutants revealed cardiac defects (dilated atrium, trabeculation defects, tachycardia and reduced contractility) as well as extracardiac developmental anomalies. RNA sequencing of tak1-/- mutant hearts showed downregulation of genes encoding core cardiac transcription factors, sarcomeric proteins and extracellular matrix proteins. Experiments with cell cultures and analysis of zebrafish larvae and gastruloids indicated that TAK1 via TAB2 and PKA-Cα is activated at the primary cilium during cardiomyogenesis and that TAK1 activation at this site is enhanced by cardiomyogenic signaling molecules, including ligands of the TGFB/BMP superfamily. Consistent with these findings, CRISPR/Cas9-mediated editing of TAK1 or administration of small molecule inhibitors targeting TAK1 inhibited ciliary signaling and cardiomyocyte differentiation in vitro, while FMD-causing mutations in TAK1 reduced its ciliary localization. In conclusion, our data establishes a central role for TAK1 and its upstream regulators in cardiac development and syndromic CHD, coordinated via the primary cilium.
Project description:Identifying causes of sporadic intellectual disability remains a considerable medical challenge. Here, we demonstrate that null mutations in the NONO gene, a member of the Drosophila Behavior Human Splicing (DBHS) protein family, are a novel cause of X-linked syndromic intellectual disability. Comparing humans to Nono-deficient mice revealed related behavioral and craniofacial anomalies, as well as global transcriptional dysregulation. Nono-deficient mice also showed deregulation of a large number of synaptic transcripts, causing a disorganization of inhibitory synapses, with impaired postsynaptic scaffolding of gephyrin. Alteration of gephyrin clustering could be rescued by over-expression of Gabra2 in NONO-compromised neurons. These findings link NONO to intellectual disability and first highlight the key role of DBHS proteins in functional organization of GABAergic synapses.
Project description:Identifying causes of sporadic intellectual disability remains a considerable medical challenge. Here, we demonstrate that null mutations in the NONO gene, a member of the Drosophila Behavior Human Splicing (DBHS) protein family, are a novel cause of X-linked syndromic intellectual disability. Comparing humans to Nono-deficient mice revealed related behavioral and craniofacial anomalies, as well as global transcriptional dysregulation. Nono-deficient mice also showed deregulation of a large number of synaptic transcripts, causing a disorganization of inhibitory synapses, with impaired postsynaptic scaffolding of gephyrin. Alteration of gephyrin clustering could be rescued by over-expression of Gabra2 in NONO-compromised neurons. These findings link NONO to intellectual disability and first highlight the key role of DBHS proteins in functional organization of GABAergic synapses.
Project description:We generated iPSCs from control and ciliopathy cases and differentiated them into polarized 3D-adherent retinal sheets that could recapitulate normal photoreceptor development and disease state, respectively.
Project description:Bialleleic pathogenic variants in LCA5 cause one of the most severe forms of Leber congenital amaurosis, an early-onset retinal disease that results in severe visual impairment. Here, we report the use of gene editing to generate isogenic LCA5 knock-out (LCA5 KO) induced pluripotent stem cells (iPSC) and their differentiation to retinal organoids. The molecular and cellular phenotype of the LCA5 KO retinal organoids was studied in detail and compared to isogenic controls as well as patient-derived retinal organoids. The absence of LCA5 was confirmed in retinal organoids by immunohistochemistry and western blotting. There were no major changes in retinal organoid differentiation or ciliation, however, the localisation of CEP290 and IFT88 was significantly altered in LCA5 KO and patient photoreceptor cilia with extension along the axoneme. The LCA5-deficient organoids also had shorter outer segments and rhodopsin was mislocalised to the outer nuclear layer. We also identified transcriptomic and proteomic changes associated with the loss of LCA5. Importantly, treatment with the small molecules eupatilin, fasudil or a combination of both drugs improved rhodopsin traffic to the outer segment and reduced mislocalisation of rhodopsin in the outer nuclear layer. The treatments also effectively reduced CEP290 and IFT88 accumulation along the cilia. The improvements in cilia-associated protein localisation and traffic were accompanied by significant changes in the transcriptome towards control gene expression levels in many of the differentially expressed genes. In summary, iPSC-derived retinal organoids are a powerful model for investigating the molecular and cellular changes associated with loss of LCA5 function and highlight the therapeutic potential of small molecules to treat retinal ciliopathies.
Project description:This study investigated the effect of the Gnat1 (rod transducin alpha subunit) gene deficiency in Gnat1rd17 mice on the retinal transcriptome remodeling, and whether this remodeling is protective or maladaptive with regard to photoreceptor damage driven by autoimmune process. The results of this study showed that Gnat1rd17 mice exhibited transcriptomic changes indicative of remodeling in photoreceptor segments and connecting cilium, deregulated inflammatory pathways and dopaminergic signaling, followed by development of exacerbated experimental autoimmune uveoretinitis, which was ameliorated by dopamine replacement. These findings suggest rod transducin alpha subunit a critical modulator of retinal homeostasis and immune response through regulation of retinal dopaminergic system.