Biology subjects

Wiegering, A.

Publications and source records attributed to Wiegering, A..

7 recordsLinked to original sources

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↗

bioRxiv2023

Stabilisation of β-Catenin-WNT signalling by USP10 in APC-truncated colorectal cancer drives cancer stemness and enables super-competitor signalling

The contribution of deubiquitylating enzymes to {beta}-Catenin stabilisation in intestinal stem cells and colorectal cancer (CRC) is poorly understood. Here, we report the deubiquitylase USP10 as an APC-truncation- specific enhancer of {beta}-Catenin stability, potentiating WNT signalling in CRC and cancer stem cells. Mechanistically, interaction studies in various CRC cell lines and in vitro binding studies, together with computational modelling, revealed that USP10 binding to {beta}-Catenin is mediated via the unstructured N-terminus of USP10 and requires the absence of full-length APC. Notably, loss of USP10 in CRISPR engineered intestinal organoids reduces tumorigenic properties of CRC and blocks the super competitor-signalling of APC-mutated CRC. Furthermore, reduction of USP10 induces the expression of differentiation genes, and opposes the APC-truncated phenotype in an intestinal hyperplasia model of D.melanogaster. Taken together, our findings reveal USP10s role in intestinal tumourigenesis by stabilising {beta}-Catenin, leading to aberrant WNT signalling, enhancing cancer cell stemness and implicate the DUB USP10 as a cancer specific therapeutic vulnerability in Apc truncated CRC.

cancer 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↗

bioRxiv2020

Gain-of-function mutation in Gli3 causes ventricular septal defects

Ventricular septal defects (VSDs) are developmental disorders, characterised by a gap in the septum between the right and the left ventricle, that lead to life-threatening heart defects. At present, the only curative treatment of VSDs is surgical closure. Since these surgeries comprise several severe risks, the development of alternative therapies against VSDs is urgently needed. To develop such therapies, the current knowledge of the molecular factors and mechanisms underlying VSDs has to be increased. Based on our previous data, we analysed the relevance of the HH signalling pathway mediator GLI3 in ventricular septum (VS) formation. GLI3 functions as both a transcriptional activator (GLI3-A) and repressor (GLI3-R). By analysing two different mouse Gli3 mutants, we revealed that the lack of GLI3-A with simultaneous presence of GLI3-R impairs cilia-mediated PDGFR signalling causing reduced cell proliferation and in consequence the development of VSDs. Moreover, we showed that the rescue of PDGFR signalling restores cell proliferation. Since VSDs are also appear in humans with comparable gain-of-function mutations in GLI3, our findings propose activators of PDGFR signalling as potential agents against the development of VSDs. SUMMARYThe article reports how a gain-of-function mutation of Gli3 causes ventricular septal defects and paves the way for therapies tackling these congenital heart defects.

developmental biology↗