Project description:Glia assess axon structure to modulate myelination and axon repair. Whether glia similarly detect dendrites and their substructures is not well understood. Here, we show that glia monitor the integrity of dendrite substructures and transiently protect their perturbation. We demonstrate that disruption of C. elegans sensory neuron dendrite cilia elicits acute glial responses, including increased accumulation of glia-derived extracellular matrix around cilia, changes in gene expression, and alteration of secreted protein repertoire. DGS-1, a 7-transmembrane domain neuronal protein, and FIG-1, a multifunctional thrombospondin-domain glial protein, are required for glial detection of cilia integrity, physically interact, and exhibit mutually-dependent localization to and around cilia, respectively. Glial responses to dendrite cilia disruption transiently protect against damage. Thus, our studies uncover a homeostatic, protective, dendrite glia signaling interaction regulating dendrite substructure integrity.
2024-12-06 | GSE282640 | GEO
Project description:Glia detect and transiently protect against dendrite substructure disruption: Whole Genome Sequencing
Project description:Sampling the live brain is difficult and dangerous, and withdrawing cerebrospinal fluid is uncomfortable and frightening to the subject, so new sources of real-time analysis are constantly sought. Cell-free DNA (cfDNA) derived from glia and neurons offers the potential for wide-ranging neurological disease diagnosis and monitoring. However, new laboratory and bioinformatic strategies are needed. DNA methylation patterns on individual cfDNA fragments can be used to ascribe their cell-of-origin. Here we describe bisulfite sequencing assays and bioinformatic processing methods to identify cfDNA derived from glia and neurons. In proof-of-concept experiments we describe the presence of both glia- and neuron-cfDNA in the blood plasma of human subjects following mild trauma. These detection of glia- and neuron-cfDNA represents a significant step forward in the translation of liquid biopsies for neurological diseases.
Project description:An animal’s skin provides a first point of contact with the sensory environment, including noxious cues that elicit protective behavioral responses. Nociceptive somatosensory neurons densely innervate and intimately interact with epidermal cells to receive these cues, however the mechanisms by which epidermal interactions shape processing of noxious inputs is still poorly understood. Here, we identify a role for dendrite intercalation between epidermal cells in tuning sensitivity of Drosophila larvae to noxious mechanical stimuli. In wild-type larvae, dendrites of nociceptive class IV da neurons intercalate between epidermal cells at apodemes, which function as body wall muscle attachment sites, but not at other sites in the epidermis. From a genetic screen we identified miR-14 as a regulator of dendrite positioning in the epidermis: miR-14 is expressed broadly in the epidermis but not in apodemes, and miR-14 inactivation leads to excessive apical dendrite intercalation between epidermal cells. We found that miR-14 regulates expression and distribution of the epidermal Innexins ogre and Inx2 and that these epidermal gap junction proteins restrict epidermal dendrite intercalation. Finally, we found that altering the extent of epidermal dendrite intercalation had corresponding effects on nociception: increasing epidermal intercalation sensitized larvae to noxious mechanical inputs and increased mechanically evoked calcium responses in nociceptive neurons, whereas reducing epidermal dendrite intercalation had the opposite effects. Altogether, these studies identify epidermal dendrite intercalation as a mechanism for mechanical coupling of nociceptive neurons to the epidermis, with nociceptive sensitivity tuned by the extent of intercalation.
Project description:Transcription factors specify the fate and connectivity of developing neurons. We investigate how a lineage-specific transcription factor, Acj6, controls the precise dendrite targeting of Drosophila olfactory projection neurons (PNs) by regulating the expression of cell-surface proteins. Quantitative cell-surface proteomic profiling of wild-type and acj6 mutant PNs in intact developing brains and a proteome-informed genetic screen identified PN surface proteins that execute Acj6-regulated wiring decisions. These include canonical cell adhesion molecules and proteins previously not associated with wiring, such as Piezo, whose mechanosensitive ion channel activity is dispensable for its function in PN dendrite targeting. Comprehensive genetic analyses revealed that Acj6 employs unique sets of cell-surface proteins in different PN types for dendrite targeting. Combinatorial expression of Acj6 wiring executors rescued acj6 mutant phenotypes with higher efficacy and breadth than expression of individual executors. Thus, Acj6 controls wiring specificity of different neuron types by specifying distinct combinatorial expression of cell-surface executors.
Project description:To identify the gene expression profile of enteric glia and assess the transcriptional similarity between enteric and extraenteric glia, we performed RNA sequencing analysis on PLP1-expressing cells in the mouse intestine. This analysis shows that enteric glia are transcriptionally unique and distinct from other cell types in the nervous system. Enteric glia express many genes characteristic of the myelinating glia, Schwann cells and oli- godendrocytes, although there is no evidence of myelination in the murine ENS. Total RNA expression profiles of PLP1 expressing enteric glial cells (GFP+) and non-glial cells (GFP-negative) were obtained from the ileum and colon of juvenile PLP1-eGFP transgenic mice.
Project description:To investigate the molecular mechanism underlying activity-dependent dendrite development regulated by Cdk5, an unbiased microarray analysis was performed to identify activity-dependent genes differentially regulated in cortical neurons from E18 Cdk5-knockout embryos.
Project description:Some cuboidal osteoblasts differentiate into bone-embedded, dendrite-bearing osteocytes through the poorly-understood process of osteocytogenesis. Here, we report that the transcription factor Sp7 plays an essential role in osteocytogenesis. Severe defects in bone integrity and osteocyte dendrite morphology are noted in mice lacking Sp7 at the stage of the osteoblast-to-osteocyte transition. In osteocytes, Sp7 controls expression of a neuronally-enriched gene network. Analysis of the osteocyte-specific Sp7 cistrome reveals distinct genomic binding motifs and target sites distinct from those in osteoblasts. Amongst osteocyte-specific Sp7 targets, the secreted peptide osteocrin rescues Sp7-deficient defects. Single-cell transcriptional profiling of cells undergoing osteocytogenesis identifies novel Sp7-dependent transitional cell types enriched in genes linked to human fracture risk. Finally, humans with an SP7 R316C mutation display osteocyte morphology defects similar to those observed in mouse models. These findings demonstrate that cuboidal osteoblasts use a neuronally-enriched Sp7/osteocrin gene expression program to differentiate into dendrite-bearing osteocytes.
Project description:Some cuboidal osteoblasts differentiate into bone-embedded, dendrite-bearing osteocytes through the poorly-understood process of osteocytogenesis. Here, we report that the transcription factor Sp7 plays an essential role in osteocytogenesis. Severe defects in bone integrity and osteocyte dendrite morphology are noted in mice lacking Sp7 at the stage of the osteoblast-to-osteocyte transition. In osteocytes, Sp7 controls expression of a neuronally-enriched gene network. Analysis of the osteocyte-specific Sp7 cistrome reveals distinct genomic binding motifs and target sites distinct from those in osteoblasts. Amongst osteocyte-specific Sp7 targets, the secreted peptide osteocrin rescues Sp7-deficient defects. Single-cell transcriptional profiling of cells undergoing osteocytogenesis identifies novel Sp7-dependent transitional cell types enriched in genes linked to human fracture risk. Finally, humans with an SP7 R316C mutation display osteocyte morphology defects similar to those observed in mouse models. These findings demonstrate that cuboidal osteoblasts use a neuronally-enriched Sp7/osteocrin gene expression program to differentiate into dendrite-bearing osteocytes.