Biology subjects

Theil, T.

Publications and source records attributed to Theil, T..

5 recordsLinked to original sources

bioRxiv2025

ASD mutations in the ciliary gene CEP41 impact development of projection neurons and interneurons in a human cortical organoid model

Primary cilia control cell-cell signalling and their dysfunction has been implicated in Autism Spectrum Disorders (ASD) but their roles in the ASD aetiology remain largely unexplored. Here, we analysed the impact of ASD mutations in CEP41 using human corticogenesis. CEP41 encodes a centrosomal protein located at the basal body and the ciliary axoneme and is mutated in ASD individuals and in Joubert syndrome, a ciliopathy with high incidence of ASD. To gain insights into CEP41s role in ASD aetiology, we characterised human cortical organoids carrying the CEP41 R242H point mutations found in ASD individuals. This mutation did not interfere with CEP41s ciliary localisation but cilia were shorter and had lower levels of tubulin polyglutamylation, which is indicative of altered cilia stability and signalling. Moreover, scRNAseq analyses revealed that the expression of several transcription factors with critical roles in interneuron development was altered in mutant interneurons and their progenitors. The CEP41 mutation also caused decreased cortical progenitor proliferation and an augmented formation of upper layer cortical neurons. Taken together, these findings indicate that CEP41 controls excitatory and inhibitory neuron differentiation, alterations in which might lead to an excitation/inhibition imbalance that is widely recognized as a convergent mechanism underlying neurodevelopmental disorders.

developmental biology↗

bioRxiv2024

Identification of Pappa and Sall3 as Gli3 direct target genes acting downstream of cilia signalling in corticogenesis

The cerebral cortex is critical for advanced cognitive functions and relies on a vast network of neurons to carry out its highly intricate neural tasks. Generating cortical neurons in accurate numbers hinges on cell signalling orchestrated by primary cilia to coordinate the proliferation and differentiation of cortical stem cells. While recent research has shed light on multiple ciliary roles in corticogenesis, specific mechanisms downstream of cilia signalling remain largely unexplored. We previously showed that an excess of early-born cortical neurons in mice mutant for the ciliary gene Inpp5e was rescued by re-introducing Gli3 repressor. By comparing expression profiles between Inpp5e and Gli3 mutants, we here identified novel Gli3 target genes. This approach highlighted the transcription factor gene Sall3 and Pappalysin1 (Pappa), a metalloproteinase involved in IGF signalling, as up-regulated genes. Further examination revealed that Gli3 directly binds to Sall3 and Pappa enhancers and suppresses their activity in the dorsal telencephalon. Collectively, our analyses provide important mechanistic insights into how primary cilia govern the behaviour of neural stem cells, ultimately ensuring the production of adequate numbers of neurons during corticogenesis. SUMMARY STATEMENTThis study reports how cilia control gene expression via Gli3 in the developing murine cerebral cortex.

developmental biology↗

bioRxiv2022

16p11.2 locus decelerates subpallial maturation and limits variability in human iPSC-derived ventral telencephalic organoids

Inhibitory interneurons regulate the activity of cortical circuitry, and their dysfunction has been implicated in Autism Spectrum Disorder (ASD). 16p11.2 microdeletions are genetically linked to 1% of ASD. However, there have been few studies of the effects of this microdeletion on interneuron development. Using ventral telencephalic organoids derived from human induced pluripotent stem cells, we investigated the effect of this microdeletion on organoid size, progenitor proliferation and organisation into neural rosettes, ganglionic eminence (GE) marker expression at early developmental timepoints and expression of the neuronal marker, NEUN at later stages. Early deletion organoids exhibited significantly greater variations in size with concomitant increases in relative neural rosette area and the expression of the ventral telencephalic marker, COUPTFII, with significantly increased variability in these properties. Cell cycle analysis revealed a significant increase in total cell cycle length caused primarily by an elongated G1-phase, the duration of which also varied significantly more than normal. Late deletion organoids increased their expression of the neuronal marker NEUN. We propose that 16p11.2 microdeletions increase developmental variability and may contribute to ASD aetiology by lengthening the cell cycle of ventral progenitors, promoting premature differentiation into interneurons. Summary StatementUsing 3D-region-specific organoids, we demonstrate that 16p11.2 deletion increases variability and prolongs the cell cycle of human subpallial progenitors by lengthening their G1 phase.

developmental biology↗

bioRxiv2021

The ciliary gene INPP5E confers dorsal telencephalic identity to human cortical organoids by negatively regulating Sonic Hedgehog signalling

Defects in primary cilia, cellular antennas that controls multiple intracellular signalling pathways, underlie several neurodevelopmental disorders, but how cilia control essential steps in human brain formation remains elusive. Here, we show that cilia are present on the apical surface of radial glial cells in human foetal forebrain. Interfering with cilia signalling in human organoids by mutating the INPP5E gene leads to the formation of ventral telencephalic cell types instead of cortical progenitors and neurons. INPP5E mutant organoids also showed increased SHH signalling and cyclopamine treatment partially rescued this ventralisation. In addition, ciliary expression of SMO was increased and the integrity of the transition zone was compromised. Overall, these findings establish the importance of primary cilia for dorsal/ventral patterning in human corticogenesis, indicate a tissue specific role of INPP5E as a negative regulator of SHH signalling and have implications for the emerging roles of cilia in the pathogenesis of neurodevelopmental disorders.

developmental biology↗

bioRxiv2020

A transient role of primary cilia in controlling direct versus indirect neurogenesis in the developing cerebral cortex

During the development of the cerebral cortex, neurons are generated directly from radial glial cells or indirectly via basal progenitors. The balance between these division modes determines the number and types of neurons formed in the cortex thereby affecting cortical functioning. Here, we investigate the role of primary cilia in this process. We show that a mutation in the ciliary gene Inpp5e leads to a transient increase in direct neurogenesis and subsequently to an overproduction of layer V neurons in newborn mice. Loss of Inpp5e also affects ciliary structure coinciding with increased Akt and mTOR signalling and reduced Gli3 repressor levels. Genetically re-storing Gli3 repressor rescues the decreased indirect neurogenesis in Inpp5e mutants. Overall, our analyses reveal how primary cilia determine neuronal subtype composition of the cortex by controlling direct vs indirect neurogenesis. These findings have implications for understanding cortical malformations in ciliopathies with INPP5E mutations.

developmental biology↗