Primary Cilia in Brain Development and Diseases

Pathogenic variants in autism gene KATNAL2 cause hydrocephalus and disrupt neuronal connectivity by impairing ciliary microtubule dynamics

Enlargement of the cerebrospinal fluid (CSF)-filled brain ventricles (cerebral ventriculomegaly), the cardinal feature of congenital hydrocephalus (CH), is increasingly recognized among patients with autism spectrum disorders (ASD). KATNAL2, a member of Katanin family microtubule-severing ATPases, is a known ASD risk gene, but its roles in human brain development remain unclear. Here, we show that nonsense truncation of Katnal2 (Katnal2Δ17) in mice results in classic ciliopathy phenotypes, including impaired spermatogenesis and cerebral ventriculomegaly. In both humans and mice, KATNAL2 is highly expressed in ciliated radial glia of the fetal ventricular-subventricular zone as well as in their postnatal ependymal and neuronal progeny. The ventriculomegaly observed in Katnal2Δ17 mice is associated with disrupted primary cilia and ependymal planar cell polarity that results in impaired cilia-generated CSF flow. Further, prefrontal pyramidal neurons in ventriculomegalic Katnal2Δ17 mice exhibit decreased excitatory drive and reduced high-frequency firing. Consistent with these findings in mice, we identified rare, damaging heterozygous germline variants in KATNAL2 in five unrelated patients with neurosurgically treated CH and comorbid ASD or other neurodevelopmental disorders. Mice engineered with the orthologous ASD-associated KATNAL2 F244L missense variant recapitulated the ventriculomegaly found in human patients. Together, these data suggest KATNAL2 pathogenic variants alter intraventricular CSF homeostasis and parenchymal neuronal connectivity by disrupting microtubule dynamics in fetal radial glia and their postnatal ependymal and neuronal descendants. The results identify a molecular mechanism underlying the development of ventriculomegaly in a genetic subset of patients with ASD and may explain persistence of neurodevelopmental phenotypes in some patients with CH despite neurosurgical CSF shunting.

Ciliogenesis defects after neurulation impact brain development and neuronal activity in larval zebrafish

Cilia are slender, hair-like structures extending from cell surfaces and playing essential roles in diverse physiological processes. Within the nervous system, primary cilia contribute to signaling and sensory perception, while motile cilia facilitate cerebrospinal fluid flow. Here, we investigated the impact of ciliary loss on neural circuit development using a zebrafish line displaying ciliogenesis defects. We found that cilia defects after neurulation affect neurogenesis and brain morphology, especially in the cerebellum, and lead to altered gene expression profiles. Using whole brain calcium imaging, we measured reduced light-evoked and spontaneous neuronal activity in all brain regions. By shedding light on the intricate role of cilia in neural circuit formation and function in the zebrafish, our work highlights their evolutionary conserved role in the brain and sets the stage for future analysis of ciliopathy models.

Lineage-specific splicing regulation of MAPT gene in the primate brain

Divergence of precursor messenger RNA (pre-mRNA) alternative splicing (AS) is widespread in mammals, including primates, but the underlying mechanisms and functional impact are poorly understood. Here, we modeled cassette exon inclusion in primate brains as a quantitative trait and identified 1,170 (∼3%) exons with lineage-specific splicing shifts under stabilizing selection. Among them, microtubule-associated protein tau (MAPT) exons 2 and 10 underwent anticorrelated, two-step evolutionary shifts in the catarrhine and hominoid lineages, leading to their present inclusion levels in humans. The developmental-stage-specific divergence of exon 10 splicing, whose dysregulation can cause frontotemporal lobar degeneration (FTLD), is mediated by divergent distal intronic MBNL-binding sites. Competitive binding of these sites by CRISPR-dCas13d/gRNAs effectively reduces exon 10 inclusion, potentially providing a therapeutically compatible approach to modulate tau isoform expression. Our data suggest adaptation of MAPT function and, more generally, a role for AS in the evolutionary expansion of the primate brain.

Regulatory role of primary cilia in oral and maxillofacial development and disease

Primary cilia have versatile functions, such as receiving signals from the extracellular microenvironment, mediating signaling transduction, and transporting ciliary substances, in tissue and organ development and clinical disease pathogenesis. During early development (embryos within 10 weeks) in the oral and maxillofacial region, defects in the structure and function of primary cilia can result in severe craniofacial malformations. For example, mice with mutations in the cilia-related genes Kif3a and IFT88 exhibit midline expansion and cleft lip/palate, which occur due to abnormalities in the fusion of the single frontonasal prominence and maxillary prominences. In the subsequent development of the oral and maxillofacial region, we discussed the regulatory role of primary cilia in the development of the maxilla, mandible, Meckel cartilage, condylar cartilage, lip, tongue, and tooth, among others. Moreover, primary cilia are promising regulators in some oral and maxillofacial diseases, such as tumors and malocclusion. We also summarize the regulatory mechanisms of primary cilia in oral and maxillofacial development and related diseases, including their role in various signaling transduction pathways. For example, aplasia of submandibular glands in the Kif3a mutant mice is associated with a decrease in SHH signaling within the glands. This review summarizes the similarities and specificities of the role of primary cilia in tissue and organ development and disease progression in the oral and maxillofacial region, which is expected to contribute several ideas for the treatment of primary cilia-related diseases.

Mechanisms underlying morphological and functional changes of cilia in fibroblasts derived from patients bearing ARL3T31A and ARL3T31A/C118F mutations

ARL3 is essential for cilia development, and mutations in ARL3 are closely associated with ciliopathies. In a previous study, we observed distinct phenotypes of retinal dystrophy in patients with heterozygous ARL3T31A and compound heterozygous ARL3T31A/C118F mutations, indicating that different mutation types may exert diverse effects on their functions. Here, we generated transformed immortal fibroblast cells from patients carrying heterozygous ARL3T31A and compound heterozygous ARL3T31A/C118F mutations, and systematically evaluated their cilia morphology and function, which were further validated in ARPE-19 cells. Results showed that both ARL3T31A and ARL3T31A/C118F mutations led to a decrease in cilium formation. The ARL3T31A/C118F mutations caused significantly elongated cilia and impaired retrograde transport, whereas the ARL3T31A mutation did not induce significant changes in fibroblasts. RNA-sequencing results indicated that compared to ARL3T31A , ARL3T31A/C118F fibroblasts exhibited a higher enrichment of biological processes related to neuron projection development, tissue morphogenesis, and extracellular matrix (ECM) organization, with noticeable alterations in pathways such as ECM-receptor interaction, focal adhesion, and TGF-β signaling. Similar changes were observed in the proteomic results in ARPE-19 cells. Core regulated genes including IQUB, UNC13D, RAB3IP, and GRIP1 were specifically downregulated in the ARL3T31A/C118F group, and expressions of IQUB, NPM2, and SLC38A4 were further validated. Additionally, IQUB showed a rescuing effect on the overlong cilia observed in ARL3T31A/C118F fibroblasts. Our results not only enhance our understanding of ARL3-related diseases but also provide new insights into the analysis of heterozygous and compound heterozygous mutations in genetics.

Illumination of understudied ciliary kinases

Cilia are cellular signaling hubs. Given that human kinases are central regulators of signaling, it is not surprising that kinases are key players in cilia biology. In fact, many kinases modulate ciliogenesis, which is the generation of cilia, and distinct ciliary pathways. Several of these kinases are understudied with few publications dedicated to the interrogation of their function. Recent efforts to develop chemical probes for members of the cyclin-dependent kinase like (CDKL), never in mitosis gene A (NIMA) related kinase (NEK), and tau tubulin kinase (TTBK) families either have delivered or are working toward delivery of high-quality chemical tools to characterize the roles that specific kinases play in ciliary processes. A better understanding of ciliary kinases may shed light on whether modulation of these targets will slow or halt disease onset or progression. For example, both understudied human kinases and some that are more well-studied play important ciliary roles in neurons and have been implicated in neurodevelopmental, neurodegenerative, and other neurological diseases. Similarly, subsets of human ciliary kinases are associated with cancer and oncological pathways. Finally, a group of genetic disorders characterized by defects in cilia called ciliopathies have associated gene mutations that impact kinase activity and function. This review highlights both progress related to the understanding of ciliary kinases as well as in chemical inhibitor development for a subset of these kinases. We emphasize known roles of ciliary kinases in diseases of the brain and malignancies and focus on a subset of poorly characterized kinases that regulate ciliary biology.

Role of lipids in the control of autophagy and primary cilium signaling in neurons

The brain is, after the adipose tissue, the organ with the greatest amount of lipids and diversity in their composition in the human body. In neurons, lipids are involved in signaling pathways controlling autophagy, a lysosome-dependent catabolic process essential for the maintenance of neuronal homeostasis and the function of the primary cilium, a cellular antenna that acts as a communication hub that transfers extracellular signals into intracellular responses required for neurogenesis and brain development. A crosstalk between primary cilia and autophagy has been established; however, its role in the control of neuronal activity and homeostasis is barely known. In this review, we briefly discuss the current knowledge regarding the role of autophagy and the primary cilium in neurons. Then we review the recent literature about specific lipid subclasses in the regulation of autophagy, in the control of primary cilium structure and its dependent cellular signaling in physiological and pathological conditions, specifically focusing on neurons, an area of research that could have major implications in neurodevelopment, energy homeostasis, and neurodegeneration.

IFT80 promotes early bone healing of tooth sockets through the activation of TAZ/RUNX2 pathway

Intraflagellar transport (IFT) proteins have been reported to regulate cell growth and differentiation as the essential functional component of primary cilia. The effects of IFT80 on early bone healing of extraction sockets have not been well studied. To investigate whether deletion of Ift80 in alveolar bone-derived mesenchymal stem cells (aBMSCs) affected socket bone healing, we generated a mouse model of specific knockout of Ift80 in Prx1 mesenchymal lineage cells (Prx1Cre ;IFT80f/f ). Our results demonstrated that deletion of IFT80 in Prx1 lineage cells decreased the trabecular bone volume, ALP-positive osteoblastic activity, TRAP-positive osteoclastic activity, and OSX-/COL I-/OCN-positive areas in tooth extraction sockets of Prx1Cre ; IFT80f/f mice compared with IFT80f/f littermates. Furthermore, aBMSCs from Prx1Cre ; IFT80f/f mice showed significantly decreased osteogenic markers and downregulated migration and proliferation capacity. Importantly, the overexpression of TAZ recovered significantly the expressions of osteogenic markers and migration capacity of aBMSCs. Lastly, the local administration of lentivirus for TAZ enhanced the expression of RUNX2 and OSX and promoted early bone healing of extraction sockets from Prx1Cre ; IFT80f/f mice. Thus, IFT80 promotes osteogenesis and early bone healing of tooth sockets through the activation of TAZ/RUNX2 pathway.

Compartmentalized ciliation changes of oligodendrocytes in aged mouse optic nerve

Primary cilia are microtubule-based sensory organelles that project from the apical surface of most mammalian cells, including oligodendrocytes, which are myelinating cells of the central nervous system (CNS) that support critical axonal function. Dysfunction of CNS glia is associated with aging-related white matter diseases and neurodegeneration, and ciliopathies are known to affect CNS white matter. To investigate age-related changes in ciliary profile, we examined ciliary length and frequency in the retinogeniculate pathway, a white matter tract commonly affected by diseases of aging but in which expression of cilia has not been characterized. We found expression of Arl13b, a marker of primary cilia, in a small group of Olig2-positive oligodendrocytes in the optic nerve, optic chiasm, and optic tract in young and aged C57BL/6 wild-type mice. While the ciliary length and ciliated oligodendrocyte cells were constant in young mice in the retinogeniculate pathway, there was a significant increase in ciliary length in the anterior optic nerve as compared to the aged animals. Morphometric analysis confirmed a specific increase in the ciliation rate of CC1+ /Olig2+ oligodendrocytes in aged mice compared with young mice. Thus, the prevalence of primary cilia in oligodendrocytes in the visual pathway and the age-related changes in ciliation suggest that they may play important roles in white matter and age-associated optic neuropathies.

Identification of new ciliary signaling pathways in the brain and insights into neurological disorders

Primary cilia are conserved sensory hubs essential for signaling transduction and embryonic development. Ciliary dysfunction causes a variety of developmental syndromes with neurological features and cognitive impairment, whose basis mostly remains unknown. Despite connections to neural function, the primary cilium remains an overlooked organelle in the brain. Most neurons have a primary cilium; however, it is still unclear how this organelle modulates brain architecture and function, given the lack of any systemic dissection of neuronal ciliary signaling. Here, we present the first in vivo glance at the molecular composition of cilia in the mouse brain. We have adapted in vivo BioID (iBioID), targeting the biotin ligase BioID2 to primary cilia in neurons. We identified tissue-specific signaling networks enriched in neuronal cilia, including Eph/Ephrin and GABA receptor signaling pathways. Our iBioID ciliary network presents a wealth of neural ciliary hits that provides new insights into neurological disorders. Our findings are a promising first step in defining the fundamentals of ciliary signaling and their roles in shaping neural circuits and behavior. This work can be extended to pathological conditions of the brain, aiming to identify the molecular pathways disrupted in the brain cilium. Hence, finding novel therapeutic strategies will help uncover and leverage the therapeutic potential of the neuronal cilium.

Primary cilia in osteoblasts and osteocytes are required for skeletal development and mechanotransduction

Primary cilia have been involved in the development and mechanosensation of various tissue types, including bone. In this study, we explored the mechanosensory role of primary cilia in bone growth and adaptation by examining two cilia specific genes, IFT88 and MKS5, required for proper cilia assembly and function. To analyze the role of primary cilia in osteoblasts, Osx1-GFP:Cre mice were bred with IFT88 LoxP/LoxP to generate mice with a conditional knockout of primary cilia in osteoblasts. A significant decrease in body weight was observed in both male (p=0.0048) and female (p=0.0374) conditional knockout (cKO) mice compared to the wild type (WT) controls. The femurs of cKO mice were significantly shorter than that of the WT mice of both male (p=0.0003) and female (p=0.0019) groups. Histological analysis revealed a significant difference in MAR (p=0.0005) and BFR/BS (p<0.0001) between female cKO and WT mice. The BFR/BS of male cKO mice was 58.03% lower compared to WT mice. To further investigate the role of primary cilia in osteocytes, Dmp1-8kb-Cre mice were crossed with MKS5 LoxP/LoxP to generate mice with defective cilia in osteocytes. In vivo axial ulnar loading was performed on 16-week-old mice for 3 consecutive days. The right ulnae were loaded for 120 cycles/day at a frequency of 2Hz with a peak force of 2.9N for female mice and 3.2N for male mice. Load-induced bone formation was measured using histomorphometry. The relative values of MS/BS, MAR and BFR/BS (loaded ulnae minus nonloaded ulnae) in male MKS5 cKO mice were decreased by 24.88%, 46.27% and 48.24%, respectively, compared to the controls. In the female groups, the rMS/BS was 52.5% lower, the rMAR was 27.58% lower, and the rBFR/BS was 41.54% lower in MKS5 cKO mice than the WT group. Histological analysis indicated that MKS5 cKO mice showed significantly decreased response to mechanical loading compared to the controls. Taken together, these data highlight a critical role of primary cilia in bone development and mechanotransduction, suggesting that the presence of primary cilia in osteoblasts play an important role in skeletal development, and primary cilia in osteocytes mediate mechanically induced bone formation.

Permanent deconstruction of intracellular primary cilia in differentiating granule cell neurons

Primary cilia on granule cell neuron progenitors in the developing cerebellum detect sonic hedgehog to facilitate proliferation. Following differentiation, cerebellar granule cells become the most abundant neuronal cell type in the brain. While essential during early developmental stages, the fate of granule cell cilia is unknown. Here, we provide nanoscopic resolution of ciliary dynamics in situ by studying developmental changes in granule cell cilia using large-scale electron microscopy volumes and immunostaining of mouse cerebella. We found that many granule cell primary cilia were intracellular and concealed from the external environment. Cilia were disassembed in differentiating granule cell neurons in a process we call cilia deconstruction that was distinct from pre-mitotic cilia resorption in proliferating progenitors. In differentiating granule cells, ciliary loss involved unique disassembly intermediates, and, as maturation progressed, mother centriolar docking at the plasma membrane. Cilia did not reform from the docked centrioles, rather, in adult mice granule cell neurons remained unciliated. Many neurons in other brain regions require cilia to regulate function and connectivity. In contrast, our results show that granule cell progenitors had concealed cilia that underwent deconstruction potentially to prevent mitogenic hedgehog responsiveness. The ciliary deconstruction mechanism we describe could be paradigmatic of cilia removal during differentiation in other tissues.

Extracellular vesicles-Mediators of opioid use disorder?

Opioid use disorder (OUD) is a growing health emergency in the United States leading to an epidemic of overdose deaths. OUD is recognized as an addictive brain disorder resulting in psychological, cognitive and behavioural dysfunction. These observed clinical dysfunctions are a result of cellular changes that occur in the brain. Derangements in inflammation, neurogenesis and synaptic plasticity are observed in the brains of OUD patients. The mechanisms of these derangements are unclear; however, extracellular vesicles (EVs), membrane bound particles containing protein, nucleotides and lipids are currently being investigated as agents that invoke these cellular changes. The primary function of EVs is to facilitate intercellular communication by transfer of cargo (protein, nucleotides and lipids) between cells; however, changes in this cargo have been observed in models of OUD suggesting that EVs may be agents promoting the observed cellular derangements. This review summarizes evidence that altered cargo of EVs, specifically protein and miRNA, in models of OUD promote impairments in neurons, astrocytes and microglial cells. These findings support the premise that opioids alter EVs to detrimentally affect neuro-cellular function resulting in the observed addictive, psychological and neurocognitive deficits in OUD patients.

Multi-Omics Data Integration Reveals Sex-Dependent Hippocampal Programming by Maternal High-Fat Diet during Lactation in Adult Mouse Offspring

Early-life exposure to high-fat diets (HF) can program metabolic and cognitive alterations in adult offspring. Although the hippocampus plays a crucial role in memory and metabolic homeostasis, few studies have reported the impact of maternal HF on this structure. We assessed the effects of maternal HF during lactation on physiological, metabolic, and cognitive parameters in young adult offspring mice. To identify early-programming mechanisms in the hippocampus, we developed a multi-omics strategy in male and female offspring. Maternal HF induced a transient increased body weight at weaning, and a mild glucose intolerance only in 3-month-old male mice with no change in plasma metabolic parameters in adult male and female offspring. Behavioral alterations revealed by a Barnes maze test were observed both in 6-month-old male and female mice. The multi-omics strategy unveiled sex-specific transcriptomic and proteomic modifications in the hippocampus of adult offspring. These studies that were confirmed by regulon analysis show that, although genes whose expression was modified by maternal HF were different between sexes, the main pathways affected were similar with mitochondria and synapses as main hippocampal targets of maternal HF. The effects of maternal HF reported here may help to better characterize sex-dependent molecular pathways involved in cognitive disorders and neurodegenerative diseases.

A Novel Genetic Variant in MBD5 Associated with Severe Epilepsy and Intellectual Disability: Potential Implications on Neural Primary Cilia

Disruptions in the MBD5 gene have been linked with an array of clinical features such as global developmental delay, intellectual disability, autistic-like symptoms, and seizures, through unclear mechanisms. MBD5 haploinsufficiency has been associated with the disruption of primary cilium-related processes during early cortical development, and this has been reported in many neurodevelopmental disorders. In this study, we describe the clinical history of a 12-year-old child harboring a novel MBD5 rare variant and presenting psychomotor delay and seizures. To investigate the impact of MBD5 haploinsufficiency on neural primary cilia, we established a novel patient-derived cell line and used CRISPR-Cas9 technology to create an isogenic control. The patient-derived neural progenitor cells revealed a decrease in the length of primary cilia and in the total number of ciliated cells. This study paves the way to understanding the impact of MBD5 haploinsufficiency in brain development through its potential impact on neural primary cilia.

BEDwARS: a robust Bayesian approach to bulk gene expression deconvolution with noisy reference signatures

Differential gene expression in bulk transcriptomics data can reflect change of transcript abundance within a cell type and/or change in the proportions of cell types. Expression deconvolution methods can help differentiate these scenarios. BEDwARS is a Bayesian deconvolution method designed to address differences between reference signatures of cell types and corresponding true signatures underlying bulk transcriptomic profiles. BEDwARS is more robust to noisy reference signatures and outperforms leading in-class methods for estimating cell type proportions and signatures. Application of BEDwARS to dihydropyridine dehydrogenase deficiency identified the possible involvement of ciliopathy and impaired translational control in the etiology of the disorder.

NPHP1 FULL DELETION CAUSES NEPHRONOPHTHISIS AND A CONE-ROD DYSTROPHY

PURPOSE

To describe in detail the structural and functional phenotypes of a patient with cone-rod dystrophy associated with a full deletion of the NPHP1 gene.

METHODS

A 30-year-old man with a history of end-stage renal disease presented with progressive vision loss in early adulthood prompting evaluation for retinal disease. Ophthalmic evaluation was performed including visual fields, electroretinography, spectral domain optical coherence tomography and short-wavelength and near-infrared fundus autofluorescence imaging.

RESULTS

The visual acuity was 20/60 in each eye. Fundus examination revealed a subtle bull's-eye maculopathy confirmed with fundus autofluorescence. Spectral domain optical coherence tomography demonstrated perifoveal loss of the outer retinal layers with structural preservation further peripherally. Static perimetry confirmed the loss of cone greater than rod sensitivities in a manner that colocalized to structural findings. Electroretinography revealed decreased cone- and rod-mediated responses. Genetic testing confirmed a homozygous whole-gene deletion of the NPHP1 gene.

CONCLUSION

NPHP1 -associated retinal degeneration may present as a cone-rod dystrophy in addition to the previously reported rod-predominant phenotypes and can notably be associated with systemic abnormalities, including renal disease. Our work further expands on the growing literature describing the retinal disease associated with systemic ciliopathies.

De novo MCM6 variants in neurodevelopmental disorders: a recognizable phenotype related to zinc binding residues

The minichromosome maintenance (MCM) complex acts as a DNA helicase during DNA replication, and thereby regulates cell cycle progression and proliferation. In addition, MCM-complex components localize to centrosomes and play an independent role in ciliogenesis. Pathogenic variants in genes coding for MCM components and other DNA replication factors have been linked to growth and developmental disorders as Meier-Gorlin syndrome and Seckel syndrome. Trio exome/genome sequencing identified the same de novo MCM6 missense variant p.(Cys158Tyr) in two unrelated individuals that presented with overlapping phenotypes consisting of intra-uterine growth retardation, short stature, congenital microcephaly, endocrine features, developmental delay and urogenital anomalies. The identified variant affects a zinc binding cysteine in the MCM6 zinc finger signature. This domain, and specifically cysteine residues, are essential for MCM-complex dimerization and the induction of helicase activity, suggesting a deleterious effect of this variant on DNA replication. Fibroblasts derived from the two affected individuals showed defects both in ciliogenesis and cell proliferation. We additionally traced three unrelated individuals with de novo MCM6 variants in the oligonucleotide binding (OB)-fold domain, presenting with variable (neuro)developmental features including autism spectrum disorder, developmental delay, and epilepsy. Taken together, our findings implicate de novo MCM6 variants in neurodevelopmental disorders. The clinical features and functional defects related to the zinc binding residue resemble those observed in syndromes related to other MCM components and DNA replication factors, while de novo OB-fold domain missense variants may be associated with more variable neurodevelopmental phenotypes. These data encourage consideration of MCM6 variants in the diagnostic arsenal of NDD.

Neural Stem Cells as Carriers of Nucleoside-Conjugated Nanogels: A New Approach toward Cell-Mediated Delivery

Neural stem cells (NSCs) present attractive natural drug delivery systems (DDSs). Their migratory potential enables crossing of the blood-brain barrier and efficient and selective accumulation near malignant cells. Here, we present the potential of NSCs as DDSs for nucleoside analogue-conjugated nanogels (NGs). Two different approaches were investigated: the intracellular loading and extracellular cell surface decoration with NGs. For both designs, the tumor-specific migratory potentials of NSCs remained unchanged; however, the intracellular loading showed a shorter NG retention. The cell surface decoration protocol yielded a high loading capacity of 100% after 1 h and a prolonged drug retention. A redox-sensitive linker between NGs and the nucleoside analogue 5-ethynyl-2'-deoxycytidine (EdC) allowed a tumor environment-specific drug release and its efficient and preferential incorporation into the DNA of the tumor cells. Interestingly, the tumor-trafficking potentials of NSCs were significantly potentiated by irradiation of tumor cells. In conclusion, this study indicates the potentials of cell surface-decorated NSCs as DDSs for tumor-specific release, cellular uptake, and incorporation of EdC into DNA.

Pleiotropic role of TRAF7 in skull-base meningiomas and congenital heart disease

While somatic variants of TRAF7 (Tumor necrosis factor receptor-associated factor 7) underlie anterior skull-base meningiomas, here we report the inherited mutations of TRAF7 that cause congenital heart defects. We show that TRAF7 mutants operate in a dominant manner, inhibiting protein function via heterodimerization with wild-type protein. Further, the shared genetics of the two disparate pathologies can be traced to the common origin of forebrain meninges and cardiac outflow tract from the TRAF7-expressing neural crest. Somatic and inherited mutations disrupt TRAF7-IFT57 interactions leading to cilia degradation. TRAF7-mutant meningioma primary cultures lack cilia, and TRAF7 knockdown causes cardiac, craniofacial, and ciliary defects in Xenopus and zebrafish, suggesting a mechanistic convergence for TRAF7-driven meningiomas and developmental heart defects.

Altered DNA methylation and gene expression predict disease severity in patients with Aicardi-Goutières syndrome

Aicardi-Goutières Syndrome (AGS) is a rare neuro-inflammatory disease characterized by increased expression of interferon-stimulated genes (ISGs). Disease-causing mutations are present in genes associated with innate antiviral responses. Disease presentation and severity vary, even between patients with identical mutations from the same family. This study investigated DNA methylation signatures in PBMCs to understand phenotypic heterogeneity in AGS patients with mutations in RNASEH2B. AGS patients presented hypomethylation of ISGs and differential methylation patterns (DMPs) in genes involved in "neutrophil and platelet activation". Patients with "mild" phenotypes exhibited DMPs in genes involved in "DNA damage and repair", whereas patients with "severe" phenotypes had DMPs in "cell fate commitment" and "organ development" associated genes. DMPs in two ISGs (IFI44L, RSAD2) associated with increased gene expression in patients with "severe" when compared to "mild" phenotypes. In conclusion, altered DNA methylation and ISG expression as biomarkers and potential future treatment targets in AGS.

Behavioral and transcriptomic effects of the cancer treatment tamoxifen in mice

Introduction

Tamoxifen is a common treatment for estrogen receptor-positive breast cancer. While tamoxifen treatment is generally accepted as safe, there are concerns about adverse effects on cognition.

Methods

We used a mouse model of chronic tamoxifen exposure to examine the effects of tamoxifen on the brain. Female C57/BL6 mice were exposed to tamoxifen or vehicle control for six weeks; brains of 15 mice were analyzed for tamoxifen levels and transcriptomic changes, and an additional 32 mice were analyzed through a battery of behavioral tests.

Results

Tamoxifen and its metabolite 4-OH-tamoxifen were found at higher levels in the brain than in the plasma, demonstrating the facile entry of tamoxifen into the CNS. Behaviorally, tamoxifen-exposed mice showed no impairment in assays related to general health, exploration, motor function, sensorimotor gating, and spatial learning. Tamoxifen-treated mice showed a significantly increased freezing response in a fear conditioning paradigm, but no effects on anxiety measures in the absence of stressors. RNA sequencing analysis of whole hippocampi showed tamoxifen-induced reductions in gene pathways related to microtubule function, synapse regulation, and neurogenesis.

Discussion

These findings of the effects of tamoxifen exposure on fear conditioning and on gene expression related to neuronal connectivity suggest that there may be CNS side effects of this common breast cancer treatment.

Cellular and Molecular Mechanisms of Pathogenesis Underlying Inherited Retinal Dystrophies

Inherited retinal dystrophies (IRDs) are congenital retinal degenerative diseases that have various inheritance patterns, including dominant, recessive, X-linked, and mitochondrial. These diseases are most often the result of defects in rod and/or cone photoreceptor and retinal pigment epithelium function, development, or both. The genes associated with these diseases, when mutated, produce altered protein products that have downstream effects in pathways critical to vision, including phototransduction, the visual cycle, photoreceptor development, cellular respiration, and retinal homeostasis. The aim of this manuscript is to provide a comprehensive review of the underlying molecular mechanisms of pathogenesis of IRDs by delving into many of the genes associated with IRD development, their protein products, and the pathways interrupted by genetic mutation.

TMEM161B regulates cerebral cortical gyration, Sonic Hedgehog signaling, and ciliary structure in the developing central nervous system

Sonic hedgehog signaling regulates processes of embryonic development across multiple tissues, yet factors regulating context-specific Shh signaling remain poorly understood. Exome sequencing of families with polymicrogyria (disordered cortical folding) revealed multiple individuals with biallelic deleterious variants in TMEM161B, which encodes a multi-pass transmembrane protein of unknown function. Tmem161b null mice demonstrated holoprosencephaly, craniofacial midline defects, eye defects, and spinal cord patterning changes consistent with impaired Shh signaling, but were without limb defects, suggesting a CNS-specific role of Tmem161b. Tmem161b depletion impaired the response to Smoothened activation in vitro and disrupted cortical histogenesis in vivo in both mouse and ferret models, including leading to abnormal gyration in the ferret model. Tmem161b localizes non-exclusively to the primary cilium, and scanning electron microscopy revealed shortened, dysmorphic, and ballooned ventricular zone cilia in the Tmem161b null mouse, suggesting that the Shh-related phenotypes may reflect ciliary dysfunction. Our data identify TMEM161B as a regulator of cerebral cortical gyration, as involved in primary ciliary structure, as a regulator of Shh signaling, and further implicate Shh signaling in human gyral development.

Primary cilia-associated protein IFT172 in ciliopathies

Cilium is a highly conserved antenna-like structure protruding from the surface of the cell membrane, which is widely distributed on most mammalian cells. Two types of cilia have been described so far which include motile cilia and immotile cilia and the latter are also known as primary cilia. Dysfunctional primary cilia are commonly associated with a variety of congenital diseases called ciliopathies with multifaceted presentations such as retinopathy, congenital kidney disease, intellectual disability, cancer, polycystic kidney, obesity, Bardet Biedl syndrome (BBS), etc. Intraflagellar transport (IFT) is a bi-directional transportation process that helps maintain a balanced flow of proteins or signaling molecules essential for the communication between cilia and cytoplasm. Disrupted IFT contributes to the abnormal structure or function of cilia and frequently promotes the occurrence of ciliopathies. Intraflagellar transport 172 (IFT172) is a newly identified member of IFT proteins closely involved in some rare ciliopathies such as Mainzer-Saldino syndrome (MZSDS) and BBS, though the underpinning causal mechanisms remain largely elusive. In this review, we summarize the key findings on the genetic and protein characteristic of IFT172, as well as its function in intraflagellar transport, to provide comprehensive insights to understand IFT172-related ciliopathies.

The role of a ciliary GTPase in the regulation of neuronal maturation of olfactory sensory neurons

Olfactory sensory neurons (OSNs) form embryonically and mature perinatally, innervating glomeruli and extending dendrites with multiple cilia. This process and its timing are crucial for odor detection and perception and continues throughout life. In the olfactory epithelium (OE), differentiated OSNs proceed from an immature (iOSN) to a mature (mOSN) state through well-defined sequential morphological and molecular transitions, but the precise mechanisms controlling OSN maturation remain largely unknown. We have identified that a GTPase, ARL13B, has a transient and maturation state-dependent expression in OSNs marking the emergence of a primary cilium. Utilizing an iOSN-specific Arl13b-null murine model, we examined the role of ARL13B in the maturation of OSNs. The loss of Arl13b in iOSNs caused a profound dysregulation of the cellular homeostasis and development of the OE. Importantly, Arl13b null OSNs demonstrated a delay in the timing of their maturation. Finally, the loss of Arl13b resulted in severe deformation in the structure and innervation of glomeruli. Our findings demonstrate a previously unknown role of ARL13B in the maturation of OSNs and development of the OE.

Characterization of Primary Cilia Formation in Human ESC-Derived Retinal Organoids

Objectives

Primary cilia are conserved organelles found in polarized mammalian cells that regulate neuronal growth, migration, and differentiation. Proper cilia formation is essential during eye development. Our previous reports found that both amacrine and retinal ganglion cells (RGCs) contain primary cilia in primate and rodent retinas. However, whether primary cilia are present in the inner retina of human retinal organoids remains unknown. The purpose of this study is to characterize the primary cilia distribution in human embryonic stem cell (hESC-derived retinal organoid development.

Materials and Methods

Retinal organoids were differentiated from a hESC line, harvested at various developmental timepoints (day 44-day 266), and immunostained with antibodies for primary cilia, including Arl13b (for the axoneme), AC3, and Centrin3 (for the basal body). AP2α, Prox1, GAD67, Calretinin, GFAP, PKCα, and Chx10 antibodies as well as Brn3b-promoted tdTomato expression were used to visualize retinal cell types.

Results

A group of ciliated cells were present in the inner aspects of retinal organoids from day 44 to day 266 in culture. Ciliated Chx10-positive retinal progenitor cells, GFAP-positive astrocytes, and PKCα-positive rod-bipolar cells were detected later during development (day 176 to day 266). Ciliation persisted during all stages of retinal developmental in AP2α-positive amacrine cells, but it was decreased in Brn3b-positive retinal ganglion cells (RGCs) at later time points. Additionally, AC3-positive astrocytes significantly decreased during the later stages of organoid formation.

Conclusions

Amacrine cells in retinal organoids retain cilia throughout development, whereas RGC ciliation gradually and progressively decreases with organoid maturation.

The genetic background of hydrocephalus in a population-based cohort: implication of ciliary involvement

Hydrocephalus is one of the most common congenital disorders of the central nervous system and often displays psychiatric co-morbidities, in particular autism spectrum disorder. The disease mechanisms behind hydrocephalus are complex and not well understood, but some association with dysfunctional cilia in the brain ventricles and subarachnoid space has been indicated. A better understanding of the genetic aetiology of hydrocephalus, including the role of ciliopathies, may bring insights into a potentially shared genetic aetiology. In this population-based case-cohort study, we, for the first time, investigated variants of postulated hydrocephalus candidate genes. Using these data, we aimed to investigate potential involvement of the ciliome in hydrocephalus and describe genotype-phenotype associations with an autism spectrum disorder. One-hundred and twenty-one hydrocephalus candidate genes were screened in a whole-exome-sequenced sub-cohort of the Lundbeck Foundation Initiative for Integrative Psychiatric Research study, comprising 72 hydrocephalus patients and 4181 background population controls. Candidate genes containing high-impact variants of interest were systematically evaluated for their involvement in ciliary function and an autism spectrum disorder. The median age at diagnosis for the hydrocephalus patients was 0 years (range 0-27 years), the median age at analysis was 22 years (11-35 years), and 70.5% were males. The median age for controls was 18 years (range 11-26 years) and 53.3% were males. Fifty-two putative hydrocephalus-associated variants in 34 genes were identified in 42 patients (58.3%). In hydrocephalus cases, we found increased, but not significant, enrichment of high-impact protein altering variants (odds ratio 1.51, 95% confidence interval 0.92-2.51, P = 0.096), which was driven by a significant enrichment of rare protein truncating variants (odds ratio 2.71, 95% confidence interval 1.17-5.58, P = 0.011). Fourteen of the genes with high-impact variants are part of the ciliome, whereas another six genes affect cilia-dependent processes during neurogenesis. Furthermore, 15 of the 34 genes with high-impact variants and three of eight genes with protein truncating variants were associated with an autism spectrum disorder. Because symptoms of other diseases may be neglected or masked by the hydrocephalus-associated symptoms, we suggest that patients with congenital hydrocephalus undergo clinical genetic assessment with respect to ciliopathies and an autism spectrum disorder. Our results point to the significance of hydrocephalus as a ciliary disease in some cases. Future studies in brain ciliopathies may not only reveal new insights into hydrocephalus but also, brain disease in the broadest sense, given the essential role of cilia in neurodevelopment.

Brain heterotopia formation by ciliopathic breakdown of neuroepithelial and blood-cerebrospinal fluid barriers

The developmental functions of primary cilia and the downstream signaling pathways have been widely studied; however, the roles of primary cilia in the developing neurovascular system are not clearly understood. In this study, we found that ablation of genes encoding ciliary transport proteins such as intraflagellar transport homolog 88 (Ift88) and kinesin family member 3a (Kif3a) in cortical radial progenitors led to periventricular heterotopia during late mouse embryogenesis. Conditional mutation of primary cilia unexpectedly caused breakdown of both the neuroepithelial lining and the blood-choroid plexus barrier. Choroidal leakage was partially caused by enlargement of the choroid plexus in the cilia mutants. We found that the choroid plexus expressed platelet-derived growth factor A (Pdgf-A) and that Pdgf-A expression was ectopically increased in cilia-mutant embryos. Cortices obtained from embryos in utero electroporated with Pdgfa mimicked periventricular heterotopic nodules of the cilia mutant. These results suggest that defective ciliogenesis in both cortical progenitors and the choroid plexus leads to breakdown of cortical and choroidal barriers causing forebrain neuronal dysplasia, which may be related to developmental cortical malformation.

Epilepsy in Joubert Syndrome: A Still Few Explored Matter

Epilepsy is rarely associated with Joubert's syndrome and related disorders (JSRD), being reported only in 3% of cases. Few patients have been described, moreover, with poor evidences of specific seizures' semiology or standard of practice for pharmacological treatment. Epilepsy is likely to be related to brain malformations in ciliopathies. Beyond the typical hindbrain malformation, the molar tooth sign, other cerebral anomalies variably reported in JSRD, such as generalized polymicrogyria, hamartomas, periventricular nodular heterotopia, and hippocampal defects, have been described. Herein, we aimed to revise the main clinical and etiopathogenetic characteristics of epilepsy associated with JSRD.

Cholesterol and Phosphoinositides in Cilia Biology

Cilia are evolutionarily conserved organelles that can be found on virtually every cell. They appear as hair-like structures emanating from the cellular surface either as single or as bundles of cilia. There, they sense external stimuli and translate them into intracellular signals. Motile cilia beat for the generation of locomotion of unicellular organisms or fluid flow in certain body cavities of vertebrate organisms. Defects in cilia are detrimental and account for the development of ciliopathies, one of the fastest-growing family of afflictions. In the past decade, membrane lipids, such as cholesterol and phosphoinositides, have emerged as essential elements in both the signal transduction via cilia and the building of cilia itself. Here, we summarize the current knowledge on the impact of cholesterol and phosphoinositides on cilium biology.

Primary Cilia Dysfunction in Neurodevelopmental Disorders beyond Ciliopathies

Primary cilia are specialized, microtubule-based structures projecting from the surface of most mammalian cells. These organelles are thought to primarily act as signaling hubs and sensors, receiving and integrating extracellular cues. Several important signaling pathways are regulated through the primary cilium including Sonic Hedgehog (Shh) and Wnt signaling. Therefore, it is no surprise that mutated genes encoding defective proteins that affect primary cilia function or structure are responsible for a group of disorders collectively termed ciliopathies. The severe neurologic abnormalities observed in several ciliopathies have prompted examination of primary cilia structure and function in other brain disorders. Recently, neuronal primary cilia defects were observed in monogenic neurodevelopmental disorders that were not traditionally considered ciliopathies. The molecular mechanisms of how these genetic mutations cause primary cilia defects and how these defects contribute to the neurologic manifestations of these disorders remain poorly understood. In this review we will discuss monogenic neurodevelopmental disorders that exhibit cilia deficits and summarize findings from studies exploring the role of primary cilia in the brain to shed light into how these deficits could contribute to neurologic abnormalities.

Alström's Syndrome: Neurological Manifestations and Genetics

Alström syndrome (ALMS) is a rare ciliopathy with pleiotropic and wide spectrum of clinical features. It is autosomal recessively inherited and associated with mutations in ALMS1, a gene involved in cilia functioning. High clinical heterogeneity is the main feature of ALMS. Cone-rod dystrophy with blindness, hearing loss, obesity, insulin resistance and hyperinsulinemia, type 2 diabetes mellitus, hypertriglyceridemia, endocrine abnormalities, cardiomyopathy, and renal, hepatic, and pulmonary anomalies are the most common signs and symptoms.

Cloning, tissue distribution of desert hedgehog (dhh) gene and expression profiling during different developmental stages of Pseudopleuronectes yokohamae

As a crucial member of the Hedgehog (Hh) protein family, desert hedgehog (dhh) plays a vital role in multiple developmental processes, cell differentiation and tissue homeostasis. However, it is unclear how it regulates development in fish. In this study, we cloned and characterized the dhh gene from Pseudopleuronectes yokohamae. The full-length cDNA of Pydhh comprises 3194 bp, with a 1386 bp open reading frame (ORF) that encodes a polypeptide of 461 amino acids with a typical HH-signal domain, Hint-N and Hint-C domains. Multiple sequence alignment revealed that the putative PyDHH protein sequence was highly conserved across species, especially in the typical domains. Phylogenetic analysis showed that the PyDHH clustered within the Pleuronectiformes. Real-time quantitative PCR showed that Pydhh was detected in fourteen different tissues in adult-female and adult-male marbled flounder, and nine different tissues in juvenile fish. During early embryonic development stages, the expression of Pydhh was revealed high levels at hatching stage of embryo development. Moreover, the relative expression of Pydhh was significantly higher in the juvenile liver than adults', and higher in the female skin than the male skin. To further investigate its location, the in situ hybridization (ISH) assay was performed, the results showed that the hybridization signal was obviously expressed in the immune organs of Pseudopleuronectes yokohamae, with weak signal expression in the other tissues. Our results suggested that Pydhh is highly conserved among species and plays a vital role in embryonic development and formation of immune related organs.

Cannabinoid receptor 2 (Cb2r) mediates cannabinol (CBN) induced developmental defects in zebrafish

Of the three primary cannabinoids in cannabis: Δ⁹-Tetrahydrocannabinol (Δ⁹-THC), cannabidiol (CBD) and cannabinol (CBN), very little is known about the actions of CBN, the primary oxidative metabolite of THC. Our goal was to determine if CBN exposure during gastrulation alters embryonic development, and if so, does it act via the canonical cannabinoid receptors. Zebrafish embryos were exposed to CBN during gastrulation and exhibited dose-dependent malformations, increased mortality, decreased locomotion and a reduction in motor neuron branching. Moreover, larva showed a significant reduction in the response to sound stimuli. CBN exposure altered the development of hair cells associated with otic vesicles and the lateral line. Pharmacological block of Cb2rs with AM 630 or JTE 907 prevented many of the CBN-induced developmental defects, while block of Cb1rs with AM 251 or CP 945598 had little or no effect. Altogether we show that embryonic exposure to CBN results in alterations in embryonic growth, neuronal and hair cell development, physiology and behavior via Cb2r-mediated mechanisms.

Silver nanoparticles exposure induces developmental neurotoxicity in hiPSC-derived cerebral organoids

Silver nanoparticles (AgNPs) are used in various research fields. Although the neurotoxicity of AgNPs has been explored in animal models and 2D cell-culture models, including human stem cells, these models cannot accurately mimic the development of the human brain. Therefore, the potential mechanisms of AgNPs-induced developmental neurotoxicity in humans are still largely unclear. In this study, cerebral organoids derived from induced pluripotent stem cells were treated with 0.1 μg/mL or 0.5 μg/mL AgNPs for 7 days. At the low concentration (0.1 μg/mL), AgNPs increased the cell proliferation and inhibited the neural apoptosis in the organoids, but impaired the cilium assembly and elongation, which may perturb the cell cycle and induce abnormal cerebral-organoid growth. Conversely, at the high concentration (0.5 μg/mL), AgNPs significantly inhibited cell proliferation and induced apoptosis in cerebral organoids. High-concentration AgNPs reduced the expression and co-localization of the cytoskeleton proteins F-actin, myosin, and tubulin, thereby perturbing neurite growth. In conclusion, AgNPs exposure induces developmental neurotoxic effects in cerebral organoids and is thus a potential congenital risk factor.

Primary cilia contribute to the aggressiveness of atypical teratoid/rhabdoid tumors

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant brain tumor in infants that is characterized by loss of nuclear expression of SMARCB1 or SMARCA4 proteins. Recent studies show that AT/RTs comprise three molecular subgroups, namely AT/RT-TYR, AT/RT-MYC and AT/RT-SHH. The subgroups show distinct expression patterns of genes involved in ciliogenesis, however, little is known about the functional roles of primary cilia in the biology of AT/RT. Here, we show that primary cilia are present across all AT/RT subgroups with specific enrichment in AT/RT-TYR patient samples. Furthermore, we demonstrate that primary ciliogenesis contributes to AT/RT biology in vitro and in vivo. Specifically, we observed a significant decrease in proliferation and clonogenicity following disruption of primary ciliogenesis in AT/RT cell line models. Additionally, apoptosis was significantly increased via the induction of STAT1 and DR5 signaling, as detected by proteogenomic profiling. In a Drosophila model of SMARCB1 deficiency, concomitant knockdown of several cilia-associated genes resulted in a substantial shift of the lethal phenotype with more than 20% of flies reaching adulthood. We also found significantly extended survival in an orthotopic xenograft mouse model of AT/RT upon disruption of primary ciliogenesis. Taken together, our findings indicate that primary ciliogenesis or its downstream signaling contributes to the aggressiveness of AT/RT and, therefore, may constitute a novel therapeutic target.

Modulation of Primary Cilia by Alvocidib Inhibition of CILK1

The primary cilium provides cell sensory and signaling functions. Cilia structure and function are regulated by ciliogenesis-associated kinase 1 (CILK1). Ciliopathies caused by CILK1 mutations show longer cilia and abnormal Hedgehog signaling. Our study aimed to identify small molecular inhibitors of CILK1 that would enable pharmacological modulation of primary cilia. A previous screen of a chemical library for interactions with protein kinases revealed that Alvocidib has a picomolar binding affinity for CILK1. In this study, we show that Alvocidib potently inhibits CILK1 (IC₅₀ = 20 nM), exhibits selectivity for inhibition of CILK1 over cyclin-dependent kinases 2/4/6 at low nanomolar concentrations, and induces CILK1-dependent cilia elongation. Our results support the use of Alvocidib to potently and selectively inhibit CILK1 to modulate primary cilia.

Ciliary transition zone proteins coordinate ciliary protein composition and ectosome shedding

The transition zone (TZ) of the cilium/flagellum serves as a diffusion barrier that controls the entry/exit of ciliary proteins. Mutations of the TZ proteins disrupt barrier function and lead to multiple human diseases. However, the systematic regulation of ciliary composition and signaling-related processes by different TZ proteins is not completely understood. Here, we reveal that loss of TCTN1 in Chlamydomonas reinhardtii disrupts the assembly of wedge-shaped structures in the TZ. Proteomic analysis of cilia from WT and three TZ mutants, tctn1, cep290, and nphp4, shows a unique role of each TZ subunit in the regulation of ciliary composition, explaining the phenotypic diversity of different TZ mutants. Interestingly, we find that defects in the TZ impair the formation and biological activity of ciliary ectosomes. Collectively, our findings provide systematic insights into the regulation of ciliary composition by TZ proteins and reveal a link between the TZ and ciliary ectosomes.

Cilia project from cells to serve sensory functions, and ciliary disruption can result in multiple disorders known as ciliopathies. Here the authors show that the ciliopathy gene TCTN1 functions to regulate the ciliary transition zone and ectosome formation.

Primary cilia in the postnatal brain: Subcellular compartments for organizing neuromodulatory signaling

Primary cilia have well characterized roles in early brain development, relaying signals critical for neurogenesis and brain formation during embryonic stages. Less understood are the contributions of cilia-mediated signaling to postnatal brain function. Several cilia-localized receptors that bind neuropeptides and neurotransmitters endogenous to the brain have been identified in adult neurons, but the functional significance of signaling through these cilia-localized receptors is largely unexplored. Ciliopathic disorders in humans often manifest with neurodevelopmental abnormalities and cognitive deficits. Intriguingly, recent research has also linked several neuropsychiatric disorders and neurodegenerative diseases to ciliary dysfunction. This review summarizes recent evidence suggesting that cilia signaling may dynamically regulate postnatal neuronal physiology and connectivity, and highlights possible links among cilia, neuronal circuitry, neuron survival, and neurological disorders.

Differential requirements for the Eps15 homology Domain Proteins EHD4 and EHD2 in the regulation of mammalian ciliogenesis

The endocytic protein EHD1 controls primary ciliogenesis by facilitating fusion of the ciliary vesicle and by removal of CP110 from the mother centriole. EHD3, the closest EHD1 paralog, has a similar regulatory role, but initial evidence suggested that the other two more distal paralogs, EHD2 and EHD4 may be dispensable for ciliogenesis. Herein, we define a novel role for EHD4, but not EHD2, in regulating primary ciliogenesis. To better understand the mechanisms and differential functions of the EHD proteins in ciliogenesis, we first demonstrated a requirement for EHD1 ATP‐binding to promote ciliogenesis. We then identified two sequence motifs that are entirely conserved between EH domains of EHD1, EHD3 and EHD4, but display key amino acid differences within the EHD2 EH domain. Substitution of either P446 or E470 in EHD1 with the aligning S451 or W475 residues from EHD2 was sufficient to prevent rescue of ciliogenesis in EHD1‐depleted cells upon reintroduction of EHD1. Overall, our data enhance the current understanding of the EHD paralogs in ciliogenesis, demonstrate a need for ATP‐binding and identify conserved sequences in the EH domains of EHD1, EHD3 and EHD4 that regulate EHD1 binding to proteins and its ability to rescue ciliogenesis in EHD1‐depleted cells.

Circulating microRNA sequencing revealed miRNome patterns in hematology and oncology patients aiding the prognosis of invasive aspergillosis

Invasive aspergillosis (IA) may occur as a serious complication of hematological malignancy. Delays in antifungal therapy can lead to an invasive disease resulting in high mortality. Currently, there are no well-established blood circulating microRNA biomarkers or laboratory tests which can be used to diagnose IA. Therefore, we aimed to define dysregulated miRNAs in hematology and oncology (HO) patients to identify biomarkers predisposing disease. We performed an in-depth analysis of high-throughput small transcriptome sequencing data obtained from the whole blood samples of our study cohort of 50 participants including 26 high-risk HO patients and 24 controls. By integrating in silico bioinformatic analyses of small noncoding RNA data, 57 miRNAs exhibiting significant expression differences (P < 0.05) were identified between IA-infected patients and non-IA HO patients. Among these, we found 36 differentially expressed miRNAs (DEMs) irrespective of HO malignancy. Of the top ranked DEMs, we found 14 significantly deregulated miRNAs, whose expression levels were successfully quantified by qRT-PCR. MiRNA target prediction revealed the involvement of IA related miRNAs in the biological pathways of tumorigenesis, the cell cycle, the immune response, cell differentiation and apoptosis.

Hydrocephalus Study Design: Testing New Hypotheses in Clinical Studies and Bench-to-Bedside Research

In this article, we aimed to describe some of the currently most challenging problems in neurosurgical management of hydrocephalus and how these can be reasons for inspiration for and development of research. We chose 4 areas of focus: 2 dedicated to improvement of current treatments (shunt implant surgery and endoscopic hydrocephalus surgery) and 2 dedicated to emerging future treatment principles (molecular mechanisms of cerebrospinal fluid secretion and hydrocephalus genetics).

Cerebral Abnormalities in Spina Bifida: A Neuropathological Study

INTRODUCTION

Spina bifida (SB) is the most common neural tube defect in humans. Here, we analyzed systematically the neuropathological findings of the brain in SB cases.

METHODS

79 cases with SB aperta (SBA) and 6 cases with SB occulta (SBO) autopsied at the Charité Neuropathology from 1974 to 2000 were re-evaluated retrospectively. For this, case files and spinal cord as well as brain sections were studied.

RESULTS

While no brain malformations were detected in SBO cases, 95% of SBA cases had brain malformations. Main brain anomalies identified were hydrocephalus (71%), Chiari II malformation (36%), heterotopia (34%), other cerebellar anomalies (36%), gyrification defects (33%), and ependymal denudation (29%). Hydrocephalus was observed as early as gestational week 17 and was highly associated to Chiari II and ependymal denudation. In 55% SBA was accompanied by further anomalies not primarily affecting the CNS.

CONCLUSION

We confirm using neuropathologic methods brain malformations in most SBA but none in SBO cases. In addition to our previous radiologic study, we now demonstrate the high prevalence of cerebellar malformations and cerebral heterotopias in SBA. The early detection of hydrocephalus and Chiari II malformation in fetuses raises the question whether these arise parallel rather than in strict temporal sequence.

Post-transcriptional and Post-translational Modifications of Primary Cilia: How to Fine Tune Your Neuronal Antenna

Primary cilia direct cellular signaling events during brain development and neuronal differentiation. The primary cilium is a dynamic organelle formed in a multistep process termed ciliogenesis that is tightly coordinated with the cell cycle. Genetic alterations, such as ciliary gene mutations, and epigenetic alterations, such as post-translational modifications and RNA processing of cilia related factors, give rise to human neuronal disorders and brain tumors such as glioblastoma and medulloblastoma. This review discusses the important role of genetics/epigenetics, as well as RNA processing and post-translational modifications in primary cilia function during brain development and cancer formation. We summarize mouse and human studies of ciliogenesis and primary cilia activity in the brain, and detail how cilia maintain neuronal progenitor populations and coordinate neuronal differentiation during development, as well as how cilia control different signaling pathways such as WNT, Sonic Hedgehog (SHH) and PDGF that are critical for neurogenesis. Moreover, we describe how post-translational modifications alter cilia formation and activity during development and carcinogenesis, and the impact of missplicing of ciliary genes leading to ciliopathies and cell cycle alterations. Finally, cilia genetic and epigenetic studies bring to light cellular and molecular mechanisms that underlie neurodevelopmental disorders and brain tumors.

Regulation of Cell Delamination During Cortical Neurodevelopment and Implication for Brain Disorders

Cortical development is dependent on key processes that can influence apical progenitor cell division and progeny. Pivotal among such critical cellular processes is the intricate mechanism of cell delamination. This indispensable cell detachment process mainly entails the loss of apical anchorage, and subsequent migration of the mitotic derivatives of the highly polarized apical cortical progenitors. Such apical progenitor derivatives are responsible for the majority of cortical neurogenesis. Many factors, including transcriptional and epigenetic/chromatin regulators, are known to tightly control cell attachment and delamination tendency in the cortical neurepithelium. Activity of these molecular regulators principally coordinate morphogenetic cues to engender remodeling or disassembly of tethering cellular components and external cell adhesion molecules leading to exit of differentiating cells in the ventricular zone. Improper cell delamination is known to frequently impair progenitor cell fate commitment and neuronal migration, which can cause aberrant cortical cell number and organization known to be detrimental to the structure and function of the cerebral cortex. Indeed, some neurodevelopmental abnormalities, including Heterotopia, Schizophrenia, Hydrocephalus, Microcephaly, and Chudley-McCullough syndrome have been associated with cell attachment dysregulation in the developing mammalian cortex. This review sheds light on the concept of cell delamination, mechanistic (transcriptional and epigenetic regulation) nuances involved, and its importance for corticogenesis. Various neurodevelopmental disorders with defective (too much or too little) cell delamination as a notable etiological underpinning are also discussed.

Primary cilium in kidney development, function and disease

The primary cilium is a hair-like, microtubule-based organelle that is covered by the cell membrane and extends from the surface of most vertebrate cells. It detects and translates extracellular signals to direct various cellular signaling pathways to maintain homeostasis. It is mainly distributed in the proximal and distal tubules and collecting ducts in the kidney. Specific signaling transduction proteins localize to primary cilia. Defects in cilia structure and function lead to a class of diseases termed ciliopathies. The proper functioning of primary cilia is essential to kidney organogenesis and the maintenance of epithelial cell differentiation and proliferation. Persistent cilia dysfunction has a role in the early stages and progression of renal diseases, such as cystogenesis and acute tubular necrosis (ATN). In this review, we focus on the central role of cilia in kidney development and illustrate how defects in cilia are associated with renal disease progression.

Growth in Joubert syndrome: Growth curves and physical measurements with correlation to genotype and hepatorenal disease in 170 individuals

Joubert syndrome (JS) is a genetically heterogenous disorder of nonmotile cilia with a characteristic "molar tooth sign" on axial brain imaging. Clinical features can include developmental delay, kidney failure, liver disease, and retinal dystrophy. Prospective growth and measurement data on 170 individuals with JS were collected, including parental measurements, birth measurements, and serial measures when available. Analysis of growth parameters in the context of hepatorenal disease, genotype, and other features was performed on 100 individuals assessed at the National Institutes of Health Clinical Center. Individuals with JS had shorter stature despite normal growth velocity and were shorter than predicted for mid-parental height. Individuals were lighter in weight, resulting in a normal body mass index (BMI). Head circumference was larger, averaging 1.9 Z-scores above height. At birth, head circumference was proportional to length. Individuals with variants in CPLANE1 had a larger head circumference compared to other genotypes; individuals with evidence of liver disease had lower weight and BMI; and individuals with polydactyly had shorter height. Here we present growth curves and physical measurements for Joubert syndrome based on the largest collection of individuals with this disorder to aid in clinical management and diagnosis.

xbx-4, a homolog of the Joubert syndrome gene FAM149B1, acts via the CCRK and RCK kinase cascade to regulate cilia morphology

Primary cilia are microtubule (MT)-based organelles that mediate sensory functions in multiple cell types. Disruption of cilia structure or function leads to a diverse collection of diseases termed ciliopathies.^1-3 The highly conserved CCRK and RCK kinases (ICK/MOK/MAK) negatively regulate cilia length and structure in Chlamydomonas, C. elegans, and mammalian cells.^4-10 How the activity of this kinase cascade is tuned to precisely regulate cilia architecture is unclear. Mutations in the Domain of Unknown Function 3719 (DUF3719)-containing protein FAM149B1 have recently been shown to elongate cilia via unknown mechanisms and result in the ciliopathy Joubert syndrome.¹¹ Here we identify XBX-4, a DUF3719-containing protein related to human FAM149B1, as a regulator of the DYF-18 CCRK and DYF-5 MAK kinase pathway in C. elegans. As in dyf-18 and dyf-5 mutants,¹⁰ sensory neuron cilia are elongated in xbx-4 mutants and exhibit stabilized axonemal MTs. XBX-4 promotes DYF-18 CCRK function to regulate localization and function of DYF-5 MAK. We find that Joubert syndrome-associated mutations in the XBX-4 DUF3719 domain also elongate cilia in C. elegans. Our results identify a new metazoan-specific regulator of this highly conserved kinase pathway and suggest that FAM149B1 may similarly act via the CCRK/RCK kinase pathway to regulate ciliary homeostasis in humans.