Biology subjects

Schneider-Maunoury, S.

Publications and source records attributed to Schneider-Maunoury, S..

12 recordsLinked to original sources

bioRxiv2026

Spinal lumen remodeling under the control of Gli signaling mechanically drives roof plate cells extension

Morphogenesis often requires different cell types to coordinate their behaviors for an harmonious developpement. How these different cell type behaviors are synchronized within and between tissues remains one of the important questions to fully understand morphogenesis. We used the zebrafish developing spinal cord to study this question. At later stages of neurogenesis, the lumen of the neural tube remodels, by reducing its height dramatically to form the persisting ventral central canal, a morphogenetic process conserved in vertebrates. By combining genetics, cell signaling manipulation with antagonist drugs and high-resolution in vivo live imaging, we better characterised the dynamics and control of this remodeling process. We showed that the lumen retraction depends on Gli activity regulation, a downstream effector of the Shh morphogen signal. We further established that the lumen retraction is instrumental in the cellular elongation of spinal roof plate cells, a population that forms the ceiling of the spinal cord lumen. Our work therefore establishes that the Gli transcriptional regulators under the control of long-range morphogen Shh control lumen retraction and that this retraction is a key driver of the roof plate cells extension.

developmental biology↗

bioRxiv2026

The Joubert gene TMEM67 is required for the correct establishment of spinal dorsal identities in human organoids.

Primary cilia are essential signaling organelles that mediate key developmental pathways, including Sonic Hedgehog (SHH) and WNT, and are crucial for tissue patterning and homeostasis. Ciliary dysfunction underlies a spectrum of human ciliopathies--such as Joubert syndrome (JBTS) and Meckel syndrome (MKS)--which present with profound neurodevelopmental abnormalities. Although the role of cilia in SHH-dependent ventral spinal cord patterning is well established, their contribution to dorsal spinal cord development, particularly in human systems, remains poorly defined. To address this gap, we utilized human spinal organoids to investigate the function of a ciliopathy-associated protein in dorsal neural tube patterning downstream of BMP4, independent of exogenous SHH. Using TMEM67 knockout human iPSC-derived dorsal spinal organoids, we demonstrate that loss of TMEM67 disrupts the specification of dorsal interneurons, most notably within the dI1 lineage, while concomitantly expanding intermediate dorsal progenitor populations (dI4-dI6). These patterning defects are associated with defective roof plate induction and attenuated BMP4 signaling. Mechanistically, TMEM67 deficiency alters ciliary morphology, decreases cilia number, and impairs recruitment of BMPR2 to the ciliary base, suggesting a direct role for cilia in modulating BMP-induced dorsal spinal patterning. Together, these findings provide new mechanistic insights into the pathogenesis of ciliopathies and underscore the value of human organoid models for elucidating human-specific aspects of neurodevelopmental disorders.

developmental biology↗

bioRxiv2026

The primary cilium controls programmed cell death via its proteasome-regulating function

Primary cilia are tiny cellular protrusions of nearly every vertebrate cell controlling multiple cellular processes, such as proliferation, differentiation, migration etc. Their dysfunction results in severe human diseases collectively referred to as ciliopathies. Remarkably, many ciliopathies are associated with increased programmed cell death (PCD). However, it is largely unknown how primary cilia regulate PCD. In in vitro (murine and human cells) and in vivo (Xenopus laevis and mouse) models, we observed elevated PCD in the absence of the ciliopathy protein RPGRIP1L. Mechanistically, our data elucidated that RPGRIP1L controls PCD by governing the activity of the ciliary proteasome. By using super-resolution microscopy, we first showed that the apoptosis inducer MOAP1 localises to primary cilia. Furthermore, our investigations revealed that RPGRIP1L controls PCD via the degradation of MOAP1 by the ciliary proteasome. Based on our finding that two more ciliopathy proteins, TCTN1 and CEP290, modulate PCD via regulating the activity of the ciliary proteasome, we suggest that the proteasomal degradation of MOAP1 represents a general mechanism by which primary cilia control PCD.

cell biology↗

bioRxiv2025

FGF overactivation underlies reduced neurogenesis in cerebellar organoid models of neurodevelopmental ciliopathy

The primary cilium acts as a specialized signaling compartment that coordinates multiple developmental pathways, yet its role in regulating signaling activity during human brain development remains poorly understood. Biallelic mutations in ciliary genes cause neurodevelopmental ciliopathies such as Joubert syndrome, which are characterized by cerebellar hypoplasia and dysplasia. Here, we generated human cerebellar organoids carrying null or patient-derived mutations in RPGRIP1L, a ciliary transition zone gene associated with Joubert Syndrome, to investigate how ciliary dysfunction alters human cerebellar neurogenesis. While control organoids robustly express markers of cerebellar glutamatergic and GABAergic lineages including Purkinje cells, RPGRIP1L-deficient organoids display a consistent and severe reduction in Purkinje cell markers, accompanied by impaired neurogenesis and increased progenitor proliferation. These defects coincide with prolonged overactivation of the FGF/MAPK signaling pathway. We further show that the MAPK effector pMEK1/2 localizes at the base of primary cilia, where its levels are significantly increased in RPGRIP1L-deficient cerebellar progenitors. Pharmacological inhibition of FGF receptors reduces pMEK1/2 activation at cilia base and rescues both the proliferation-neurogenesis imbalance and Purkinje lineage defects, without restoring the underlying ciliary abnormalities. Together, our findings identify the primary cilium as a compartment that refines FGF/MAPK signaling in human cerebellar progenitors, and support a model in which RPGRIP1L restrains FGF pathway activity to promote neurogenesis. These results provide a mechanism linking ciliary dysfunction to altered cerebellar development and provide new insight into the developmental origin of cerebellar impairment in neurodevelopmental ciliopathies

developmental biology↗

bioRxiv2024

A DIFFERENTIAL REQUIREMENT FOR THE CILIOPATHY GENE RPGRIP1L IN HUMAN AND MOUSE SPINAL PROGENITOR FATE SPECIFICATION

Studying developmental processes in the context of the human central nervous system is essential to understand neurodevelopmental diseases. In this paper we perform a comparative functional study of the ciliopathy gene RPGRIP1L in human and mouse spinal development using in vitro 3D differentiation of pluripotent stem cells. RPGRIP1L, a causal gene of severe neurodevelopmental ciliopathies such as Joubert and Meckel syndromes, encodes a scaffolding protein of the ciliary transition zone involved in ciliary gating. Previous work has identified a major role for Rpgrip1l in mouse brain and spinal cord development, via controlling the Sonic Hedgehog (SHH)/GLI pathway. We show that spinal organoids derived from Rpgrip1l mutant mouse embryonic stem cells faithfully recapitulate the loss of motoneurons and the strong reduction of SHH signaling observed in the mutant mice. In contrast, human induced pluripotent stem cells mutant for RPGRIP1L produce motoneurons and activate the SHH pathway at levels similar to wild types, a property shared by human iPSCs mutant for another ciliopathy gene TMEM67. Moreover, we show that, in human RPGRIP1L mutant organoids, motoneurons acquire a more anterior identity, expressing HOX genes and other proteins normally present in the hindbrain and cervical spinal cord while motoneurons from wild type organoids strictly display a caudal brachial identity. By performing a temporal transcriptome analysis throughout the differentiation process, we find that the antero-posterior specification defect arises in early axial progenitors and correlates with the loss of cilia in these cells. Thus, this study uncovers distinct functions in humans and mice for ciliopathy proteins and a novel role for RPGRIP1L in human spinal antero-posterior patterning. These findings have important implications for understanding the role of cilia in human spinal cord development and the pathogenic mechanisms of neurodevelopmental ciliopathies.

developmental biology↗

bioRxiv2024

ASTROGLIOSIS AND NEUROINFLAMMATION UNDERLIE SCOLIOSIS UPON CILIA DYSFUNCTION

Cilia defects lead to scoliosis in zebrafish, but the underlying pathogenic mechanisms are poorly understood and may diverge depending on the mutated gene. Here, we dissected the mechanisms of scoliosis onset in a zebrafish mutant for the rpgrip1l gene encoding a ciliary transition zone protein. rpgrip1l mutant fish developed scoliosis with near-total penetrance but asynchronous onset in juveniles. Taking advantage of this asynchrony, we found that curvature onset was preceded by ventricle dilations and was concomitant to the perturbation of Reissner fiber polymerization and to the loss of multiciliated tufts around the subcommissural organ. Rescue experiments showed that Rpgrip1l was exclusively required in foxj1a-expressing cells to prevent axis curvature. Genetic interactions investigations ruled out Urp1/2 levels as a main driver of scoliosis in rpgrip1 mutants. Transcriptomic and proteomic studies identified neuroinflammation associated with increased Annexin levels as a potential mechanism of scoliosis development in rpgrip1l juveniles. Investigating the cell types associated with annexin2 over-expression, we uncovered astrogliosis, arising in glial cells surrounding the diencephalic and rhombencephalic ventricles just before scoliosis onset and increasing with time in severity. Anti-inflammatory drug treatment reduced scoliosis penetrance and severity and this correlated with reduced astrogliosis and macrophage/microglia enrichment around the diencephalic ventricle. Mutation of the cep290 gene encoding another transition zone protein also associated astrogliosis with scoliosis. Thus, we propose astrogliosis induced by perturbed ventricular homeostasis and associated with immune cell activation as a novel pathogenic mechanism of zebrafish scoliosis caused by cilia dysfunction.

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↗

bioRxiv2020

Rpgrip1l controls ciliary gating by ensuring the proper amount of Cep290 at the vertebrate transition zone

A range of severe human diseases called ciliopathies are caused by the dysfunction of primary cilia. Primary cilia are cytoplasmic protrusions consisting of the basal body (BB), the axoneme and the transition zone (TZ). The BB is a modified mother centriole from which the axoneme, the microtubule-based ciliary scaffold, is formed. At the proximal end of the axoneme, the TZ functions as the ciliary gate governing ciliary protein entry and exit. Since ciliopathies often develop due to mutations in genes encoding proteins that localise to the TZ, the understanding of the mechanisms underlying TZ function is of eminent importance. Here, we show that the ciliopathy protein Rpgrip1l governs ciliary gating by ensuring the proper amount of Cep290 at the vertebrate TZ. Further, we identified the flavonoid eupatilin as a potential agent to tackle ciliopathies caused by mutations in RPGRIP1L as it rescues ciliary gating in the absence of Rpgrip1l.

cell biology↗

bioRxiv2019

PLANAR POLARIZATION OF CILIA IN THE ZEBRAFISH FLOOR PLATE INVOLVES Par3-MEDIATED POSTERIOR LOCALIZATION OF HIGHLY MOTILE BASAL BODIES.

To produce a directional flow, ciliated epithelia display a uniform orientation of ciliary beating. Oriented beating requires planar cell polarity (PCP), which leads to planar orientation and asymmetric positioning of the ciliary basal body (BB) along the polarity axis. We took advantage of the polarized mono-ciliated epithelium of the embryonic zebrafish floor plate to investigate by live-imaging the dynamics and mechanisms of BB polarization. We showed that BBs, although bearing a cilium, were highly motile along the antero-posterior axis. BBs contacted both the anterior and the posterior membranes, with a bias towards posterior contacts from early somitogenesis on. Contacts exclusively occurred at junctional Par3 local enrichments or "patches" and were often preceded by transient membrane digitations extending towards the BB, suggesting focused cortical pulling forces. Accordingly, BBs and Par3 patches were linked by dynamic microtubules. We showed that Par3 became posteriorly enriched prior to BB posterior positioning and that floor plate polarization was impaired upon Par3 patches disruption triggered by Par3 or aPKC overexpression. In the PCP mutant Vangl2, where floor plate cells fail to polarize, we observed that BB were still motile but presented behavioral defects, such as ectopic contacts with lateral membranes that correlated with Par3 patch fragmentation and spreading to lateral membranes. Our data lead us to propose an unexpected function for posterior local Par3 enrichment in controlling BB asymmetric positioning downstream of the PCP pathway via a microtubule capture/shrinkage mechanism.

developmental biology↗

bioRxiv2019

MKS-NPHP module proteins regulate ciliary shedding in Paramecium

Ciliogenesis is a general process in eukaryotic cells and its different steps begin to be well characterised. However, the molecular mechanisms leading to decilation or ciliary shedding are still poorly understood. This process, observed from unicellular organisms such as Chlamydomonas or Paramecium to multiciliated cells from trachea or fallopian tube of vertebrates, seems to be a general process since recent observations demonstrates its requirement during the cell cycle or neurogenesis. Interestingly, in all cellular models, ciliary shedding occurs distal to the transition zone, essentially known to act as a diffusion barrier between the intracellular space and the cilium, suggesting conserved molecular mechanisms.\n\nTo determine if MKS and NPHP modules, known to cooperate to establish transition zone formation and function, could control ciliary shedding, we studied in Paramecium the function of TMEM216/MKS2 and TMEM107 (two members of the MKS module), NPHP4 (one member of the NPHP module), CEP290/NPHP6 and RPGRIP1L/MKS5. We show that all these proteins are recruited to the TZ as soon as growing cilia are detected and localise with a 9-fold symmetry at the level of the axonemal plate. Interestingly, we demonstrate that the depletion of the two MKS module proteins induces spontaneous cilia shedding, while the depletion of either NPHP4, CEP290 or RPGRIP1L inhibits the process. Our results constitute the first evidence for a role of conserved TZ proteins in deciliation and open new directions for understanding motile cilia physiology.

cell biology↗

bioRxiv2018

The Ciliopathy Gene Ftm/Rpgrip1l Controls Mouse Forebrain Patterning Via Region-Specific Modulation Of Hedgehog/Gli Signaling.

Primary cilia are essential for central nervous system development. In the mouse, they play a critical role in patterning the spinal cord and telencephalon via the regulation of Hedgehog/Gli signaling. However, despite the frequent disruption of this signaling pathway in human forebrain malformations, the role of primary cilia in forebrain morphogenesis has been little investigated outside the telencephalon. Here we studied development of the diencephalon, hypothalamus and eyes in mutant mice in which the Ftm/Rgprip1l ciliopathy gene is disrupted. At the end of gestation, Ftm-/- fetuses displayed anophthalmia, a reduction of the ventral hypothalamus and a disorganization of diencephalic nuclei and axonal tracts. In Ftm-/- embryos, we found that the ventral forebrain structures and the rostral thalamus were missing. Optic vesicles formed but lacked the optic cups. We analyzed the molecular causes of these defects. In Ftm-/- embryos, Sonic hedgehog (Shh) expression was lost in the ventral forebrain but maintained in the zona limitans intrathalamica (ZLI), the mid-diencephalic organizer. In the diencephalon, Gli activity was dampened in regions adjacent to the Shh-expressing ZLI but displayed a higher Hh-independent ground level in the other regions. Our data uncover a complex role of cilia in development of the diencephalon, hypothalamus and eyes via the region-specific control of the ratio of activator and repressor forms of the Gli transcription factors. They call for a closer examination of forebrain defects in severe ciliopathies and for a search for ciliopathy genes as modifiers in other human conditions with forebrain defects.

developmental biology↗

bioRxiv2018

An in vivo translation-reporter system for the study of protein synthesis in zebrafish embryos

Control of gene expression at the translation level is increasingly regarded as a key feature in many biological processes. Simple, inexpensive, and reliable procedures to visualise sites of protein production are required to allow observation of the spatiotemporal patterns of mRNA translation at subcellular resolution. We present a method, named SPoT (for Subcellular Patterns of Translation), developed upon the original TimeStamp technique (Lin et al., 2008), consisting in the expression of a fluorescent protein fused to a tagged, self-cleavable protease domain. Addition of a cell-permeable protease inhibitor instantly stabilizes newly produced, tagged protein allowing to distinguish recently synthesized protein from more ancient one. After a brief protease inhibitor treatment, the ratio of tagged vs non-tagged forms is highest at sites where proteins are the most recent, i.e. sites of synthesis. Therefore, by comparing tagged and non-tagged protein it is possible to spotlight sites of translation. By specifically expressing the SPoT cassette in neurons of transgenic zebrafish embryos, we reveal sites of neuronal protein synthesis in diverse cellular compartments during early development.

developmental biology↗