Project description:Complement component C3 mediates pathology in several CNS neurodegenerative diseases, but the cellular and molecular mechanisms leading to neuronal injury remain unclear. Herein, we examined how C3 deletion affects glial profiles and anterior visual pathway pathology in an animal model of neuroinflammation. scRNA-seq from mouse brain and optic nerve revealed that C3 expression defined disease-associated glial subtypes which were characterized by increased mTOR activation, cell metabolism, and translation. Deletion of C3 restored these glia towards homeostatic profiles. Myeloid-derived C3 mediated injury in optic nerve axons and retinal ganglion cells (RGCs) at the peak of EAE. To elucidate the timing of pathology we examined retinas prior to symptom onset and found reductions in Brn3a, an RGC transcription factor involved in dendritic arborization and protection from apoptosis. Our study supports a direct role for C3 in activating the mTOR-ribosomal biogenesis axis in glia which subsequently mediate early neuro-axonal stress and later synapse loss.
Project description:Complement component C3 mediates pathology in several CNS neurodegenerative diseases, but the cellular and molecular mechanisms leading to neuronal injury remain unclear. Herein, we examined how C3 deletion affects glial profiles and anterior visual pathway pathology in an animal model of neuroinflammation. scRNA-seq from mouse brain and optic nerve revealed that C3 expression defined disease-associated glial subtypes which were characterized by increased mTOR activation, cell metabolism, and translation. Deletion of C3 restored these glia towards homeostatic profiles. Myeloid-derived C3 mediated injury in optic nerve axons and retinal ganglion cells (RGCs) at the peak of EAE. To elucidate the timing of pathology we examined retinas prior to symptom onset and found reductions in Brn3a, an RGC transcription factor involved in dendritic arborization and protection from apoptosis. Our study supports a direct role for C3 in activating the mTOR-ribosomal biogenesis axis in glia which subsequently mediate early neuro-axonal stress and later synapse loss.
Project description:Excess noise damages sensory hair cells, resulting in loss of synaptic connections with auditory nerves and, in some cases, hair-cell death. The cellular mechanisms underlying mechanically induced hair-cell damage and subsequent repair are not completely understood. Hair cells in neuromasts of larval zebrafish are structurally and functionally comparable to mammalian hair cells but undergo robust regeneration following ototoxic damage. We therefore developed a model for mechanically induced hair-cell damage in this highly tractable system. Free swimming larvae exposed to strong water wave stimulus for 2 hr displayed mechanical injury to neuromasts, including afferent neurite retraction, damaged hair bundles, and reduced mechanotransduction. Synapse loss was observed in apparently intact exposed neuromasts, and this loss was exacerbated by inhibiting glutamate uptake. Mechanical damage also elicited an inflammatory response and macrophage recruitment. Remarkably, neuromast hair-cell morphology and mechanotransduction recovered within hours following exposure, suggesting severely damaged neuromasts undergo repair. Our results indicate functional changes and synapse loss in mechanically damaged lateral-line neuromasts that share key features of damage observed in noise-exposed mammalian ear. Yet, unlike the mammalian ear, mechanical damage to neuromasts is rapidly reversible.
Project description:Epilepsy is a brain condition characterized by the recurrence of unprovoked seizures. Recent studies have shown that complement component 3 (C3) aggravate the neuronal injury in epilepsy. And our previous studies revealed that TRPV1 (transient receptor potential vanilloid type 1) is involved in epilepsy. Whether complement C3 regulation of neuronal injury is related to the activation of TRPV1 during epilepsy is not fully understood. We found that in a mouse model of status epilepticus (SE), complement C3 derived from astrocytes was increased and aggravated neuronal injury, and that TRPV1-knockout rescued neurons from the injury induced by complement C3. Circular RNAs are abundant in the brain, and the reduction of circRad52 caused by complement C3 promoted the expression of TRPV1 and exacerbated neuronal injury. Mechanistically, disorders of neuron-glia interaction mediated by the C3-TRPV1 signaling pathway may be important for the induction of neuronal injury. This study provides support for the hypothesis that the C3-TRPV1 pathway is involved in the prevention and treatment of neuronal injury and cognitive disorders.
