Project description:This experiment aims to study the impact of primary cilia signaling on transcriptional programs relevant to axonal development in the mouse cerebral cortex.
Project description:Alzheimer's disease (AD) is a brain disorder manifested by a gradual decline in cognitive function due to the accumulation of extracellular amyloid plaques, disruptions in neuronal substance transport, and the degeneration of neurons. In affected neurons, incomplete clearance of toxic proteins by neighboring microglia leads to irreversible brain inflammation, for which cellular signaling is poorly understood. Through single-cell transcriptomic analysis, we discovered distinct regional differences in the ability of microglia to clear damaged neurites. Specifically, microglia in the septal region of wild type mice exhibited a transcriptomic signature resembling disease-associated microglia (DAM). These Lateral septum (LS)-enriched microglia (SEM) were associated with dense axonal bundles originating from the hippocampus. Further transcriptomic and proteomic approaches revealed that primary cilia, small hair-like structures found on cells, played a role in the regulation of microglial secretory function. Notably, primary cilia were transiently observed in less than 10% of microglia, and their presence was significantly reduced in microglia from AD mice. We observed significant changes in the expression and distribution of the secretome after inhibiting the primary cilia gene intraflagellar transport particle 88 (Ift88) in microglia. Intriguingly, inhibiting primary cilia in the SEM of AD mice resulted in the expansion of extracellular amyloid plaques and damage to adjacent neurites. These results indicate that DAM-like microglia are present in the LS, a critical target region for hippocampal nerve bundles, and that the primary ciliary signaling system regulates microglial secretion, affecting extracellular proteostasis. Age-related primary ciliopathy probably contributes to the selective sensitivity of microglia, thereby exacerbating AD. Targeting the primary ciliary signaling system could therefore be a viable strategy for modulating neuroimmune responses in AD treatments.
Project description:Analysis of epithelial explants injected with the intracellular domain of Notch (ICD) to block the formation of multi-ciliate cells, either alone or along with FoxJ1. FoxJ1 misexpression leads to the induction fo ectopic cilia in Xenopus laevis epithelia. Results show which genes are affected by FoxJ1 during the induction of ectopic cilia. Ciliated cells that produce a leftward fluid flow have been proposed to mediate left-right patterning in many vertebrate embryos. These cilia combine features of primary sensory and motile cilia, but how such cilia are specified is unknown. We address this issue by analyzing the Xenopus and Zebrafish homologs of FoxJ1, a forkhead transcription factor necessary for ciliogenesis in multi-ciliate cells of the mouse. We show that the cilia that underlie left-right patterning on the Xenopus gastrocoel roof plate (GRP) and Zebrafish Kupffer’s vesicle (KV) are severely shortened or fail to form in FoxJ1 morphants. We also show that misexpressing XFoxJ1 is sufficient to induce ectopic GRP-like cilia formation in frog embryos. Microarray analysis indicates that XFoxJ1 induces the formation of cilia by upregulating the expression of motile cilia genes. These results indicate that FoxJ1 is a critical determinant in specifying cilia used in left-right patterning. Keywords: Cilia Induction
Project description:Alpha-herpesviruses establish a life-long infection in the nervous system of the affected host; while this infection is restricted to peripheral neurons in a heathy host, it can spread within the neuronal circuitry in compromised individuals leading to adverse health consequences. Pseudorabies virus (PRV) an alpha-herpesvirus, requires the viral protein Us9 for sorting virus particles into axons. It does so by mediating an interaction of virus particles with neuronal transport machinery. Us9-mediated axonal sorting also depends on the state of neuronal maturation as the proteome composition changes with neuronal development of dendrites and axons. Immature superior cervical ganglia (SCGs) have rudimentary neurites that lack markers of mature dendrites or axons. Immature SCGs can be infected by PRV, but show markedly reduced Us9-dependent sorting into neurites. Mature SCGs abundantly express a variety of proteins characteristic of vesicle-transport machinery. Proteomics studies identified several novel Us9-associated neuronal proteins with potential roles in the regulation of axonal sorting and subsequent anterograde spread of virus particles in axons. For example, we found that SMPD4/n-sMase3, a sphingomyelinase abundant in lipid-rafts, associates with Us9 and is a negative regulator of axonal mediated spread of PRV, a potential novel antiviral function.
Project description:Background: Whereas cilia damage and reduced cilia beat frequency have been implicated as causative of reduced mucociliary clearance in smokers, theoretically mucociliary clearance could also be affected by cilia length. Based on models of mucociliary clearance predicting cilia length must exceed the 6 -7 μm airway surface fluid depth to generate force in the mucus layer, we hypothesized cilia height may be decreased in airway epithelium of normal smokers compared to nonsmokers. Methodology/Principal Findings: Cilia length in normal nonsmokers and smokers was evaluated in aldehyde-fixed, paraffin-embedded endobronchial biopsies, and air-dried and hydrated samples brushed from human airway epithelium via fiberoptic bronchoscopy. In 28 endobronchial biopsies, healthy smoker cilia length was reduced 15% compared to nonsmokers (p<0.05). In 47 air-dried samples of airway epithelial cells, smoker cilia length was reduced 13% compared to nonsmokers (p<0.0001). Analysis of the length of individual, detached cilia in 17 samples, smoker cilia length was reduced 9% compared to nonsmokers (p<0.05). Finally, in 16 fully hydrated, unfixed samples, smoker cilia length was reduced 7% compared to nonsmokers (p<0.05). Conclusions/significance: Models predict that a reduction in cilia length would reduce mucociliary clearance, suggesting that smoking-associated shorter airway epithelial cilia plays a significant role in the pathogenesis of smoking-induced lung disease.
Project description:We report that fortified levels of folic acid adversely affect cilia strucure and function. This data set agrees with previous experiements which have demonstrated that elevated folic acid levels can increase transcription variability on a genome-wide level. Furthermore, we demonstrate that among these dysregulated genes, genes contained within SYSgold cilia database are proportionally over-represented. This over-representation of cilia genes among dysregulated genes may play a key role in ciliopathys' sensitivity to elevated folic acid levels.
Project description:The primary cilium, a signaling organelle projecting from the surface of a cell, controls cellular physiology and behavior. The presence or absence of primary cilia is a distinctive feature of a given tumor type; however, whether and how the primary cilium contributes to tumorigenesis is unknown for most tumors. Medulloblastoma (MB) is a common pediatric brain cancer comprising four groups: SHH, WNT, group 3 (G3), and group 4 (G4). From 111 cases of MB, we show that primary cilia are abundant in SHH and WNT MBs but rare in G3 and G4 MBs. Using WNT and G3 MB mouse models, we show that primary cilia promote WNT MB by facilitating translation of mRNA encoding β-catenin, a major oncoprotein driving WNT MB, whereas cilium loss promotes G3 MB by disrupting cell cycle control and destabilizing the genome. Our findings reveal tumor type–specific ciliary functions and underlying molecular mechanisms. Moreover, we expand the function of primary cilia to translation control and reveal a molecular mechanism by which cilia regulate cell cycle progression, providing new frameworks for studying cilia function in normal and pathologic conditions.
Project description:RNA-seq technology was used to reveal the transcriptome changes of tubular epithelia in response to fluid flow and determine the role of primary cilia in this process. Many fluid flow-sensitive genes were identified, among which are those regulated by primary cilia sensing of fluid flow. These genes were further validated by RT-qPCR.
Project description:The identification of axonal mRNAs in model organisms has led to the discovery of many axonally translated proteins required for axon guidance and injury response. The extent to which these axonal mRNAs are conserved in humans is unknown. Here we report on the axonal transcriptome of glutamatergic neurons derived from human embryonic stem cells (hESC-neurons) grown in axon isolating microfluidic chambers. We identified mRNAs enriched in axons, representing a functionally unique local transcriptome as compared to the whole neuron transcriptome. Further, we found that the enriched functional categories within high confidence axonal transcripts resemble those in the axonal transcriptome of rat cortical neurons. Comparing our list of human axonal transcripts to similar datasets generated from embryonic and adult rat dorsal root ganglia and rat cortical neurons we found 60 mRNAs common to all four neuron types. We found that over half of these genes are associated with neurological phenotypes or diseases in model organisms and human. This data provides an important resource for studying local mRNA translation in human axons and has the potential to reveal both conserved and unique axonal mechanisms across species and neuronal types. We analyzed the axonal and whole hESC-neuron transcriptome in triplicate using the Affymetrix Human Gene 2.0 ST Array platform.