Photoactivatable or "caged" pharmacological agents combine the high spatiotemporal specificity of light application with the molecular specificity of drugs. A key factor in all optopharmacology experiments is the mechanism of uncaging, which dictates the photochemical quantum yield and determines the byproducts produced by the light-driven chemical reaction. In previous work, we demonstrated that coumarin-based photolabile groups could be used to cage tertiary amine drugs as quaternary ammonium salts.
View Article and Find Full Text PDFChemical synapses between axons and dendrites mediate neuronal intercellular communication. Here, we describe a synapse between axons and primary cilia: the axo-ciliary synapse. Using enhanced focused ion beam-scanning electron microscopy on samples with optimally preserved ultrastructure, we discovered synapses between brainstem serotonergic axons and the primary cilia of hippocampal CA1 pyramidal neurons.
View Article and Find Full Text PDFPiloerection (goosebumps) requires concerted actions of the hair follicle, the arrector pili muscle (APM), and the sympathetic nerve, providing a model to study interactions across epithelium, mesenchyme, and nerves. Here, we show that APMs and sympathetic nerves form a dual-component niche to modulate hair follicle stem cell (HFSC) activity. Sympathetic nerves form synapse-like structures with HFSCs and regulate HFSCs through norepinephrine, whereas APMs maintain sympathetic innervation to HFSCs.
View Article and Find Full Text PDFTargeting small-molecule fluorescent indicators using genetically encoded protein tags yields new hybrid sensors for biological imaging. Optimization of such systems requires redesign of the synthetic indicator to allow cell-specific targeting without compromising the photophysical properties or cellular performance of the small-molecule probe. We developed a bright and sensitive Ca indicator by systematically exploring the relative configuration of dye and chelator, which can be targeted using the HaloTag self-labeling tag system.
View Article and Find Full Text PDFSerial-section electron microscopy such as FIB-SEM (focused ion beam scanning electron microscopy) has become an important tool for neuroscientists to trace the trajectories and global architecture of neural circuits in the brain, as well as to visualize the 3D ultrastructure of cellular organelles in neurons. In this study, we examined 3D features of mitochondria in electron microscope images generated from serial sections of four regions of mouse brains: nucleus accumbens (NA), hippocampal CA1, somatosensory cortex and dorsal cochlear nucleus (DCN). We compared mitochondria in the presynaptic terminals to those in the postsynaptic/dendritic compartments, and we focused on the shape and size of mitochondria.
View Article and Find Full Text PDFMetabolic coordination between neurons and astrocytes is critical for the health of the brain. However, neuron-astrocyte coupling of lipid metabolism, particularly in response to neural activity, remains largely uncharacterized. Here, we demonstrate that toxic fatty acids (FAs) produced in hyperactive neurons are transferred to astrocytic lipid droplets by ApoE-positive lipid particles.
View Article and Find Full Text PDFOptical and electron microscopy have made tremendous inroads toward understanding the complexity of the brain. However, optical microscopy offers insufficient resolution to reveal subcellular details, and electron microscopy lacks the throughput and molecular contrast to visualize specific molecular constituents over millimeter-scale or larger dimensions. We combined expansion microscopy and lattice light-sheet microscopy to image the nanoscale spatial relationships between proteins across the thickness of the mouse cortex or the entire brain.
View Article and Find Full Text PDFWe generated a knockout mouse for the neuronal-specific β-tubulin isoform Tubb3 to investigate its role in nervous system formation and maintenance. Tubb3 mice have no detectable neurobehavioral or neuropathological deficits, and upregulation of mRNA and protein of the remaining β-tubulin isotypes results in equivalent total β-tubulin levels in Tubb3 and wild-type mice. Despite similar levels of total β-tubulin, adult dorsal root ganglia lacking TUBB3 have decreased growth cone microtubule dynamics and a decreased neurite outgrowth rate of 22% in vitro and in vivo.
View Article and Find Full Text PDFMutations in the polycystin genes, or results in Autosomal Dominant Polycystic Kidney Disease (ADPKD). Although a genetic basis of ADPKD is established, we lack a clear understanding of polycystin proteins' functions as ion channels. This question remains unsolved largely because polycystins localize to the primary cilium - a tiny, antenna-like organelle.
View Article and Find Full Text PDFIn many parts of the nervous system, signals pass across multiple synaptic relays on their way to a destination, but little is known about how these relays form and the function they serve. To get some insight into this question we ask how the connectivity patterns are organized at two successive synaptic relays in a simple, cholinergic efferent pathway. We found that the organization at successive relays in the parasympathetic nervous system strongly resemble each other despite the different embryological origin and physiological properties of the pre- and postsynaptic cells.
View Article and Find Full Text PDFCilia are highly conserved organelles, which serve critical roles in development and physiology. Motile cilia are expressed in a limited range of tissues, where they principally regulate local extracellular fluid dynamics. In contrast, primary cilia are expressed by many vertebrate cell types during interphase, and are intimately involved in the cell cycle and signal transduction.
View Article and Find Full Text PDFWell-differentiated human cancers share transcriptional programmes with the normal tissue counterparts from which they arise. These programmes broadly influence cell behaviour and function and are integral modulators of malignancy. Here, we show that the master regulator of motile ciliogenesis, FOXJ1, is highly expressed in cells along the ventricular surface of the human brain.
View Article and Find Full Text PDFMotor axons in peripheral nerves have the capacity to regenerate after injury. However, full functional motor recovery rarely occurs clinically, and this depends on the nature and location of the injury. Recent preclinical findings suggest that there may be a time after nerve injury where, while regrowth to the muscle successfully occurs, there is nevertheless a failure to re-establish motor function, suggesting a possible critical period for synapse reformation.
View Article and Find Full Text PDFProgressive multifocal leukoencephalopathy is a rare, demyelinating disease of the central nervous system caused by JC virus. Fewer than 30 cases have been reported in HIV- and non-infected children. We report the case of a 15-year-old girl with progressive multifocal leukoencephalopathy and AIDS who presented with nystagmus, dysarthria and ataxia.
View Article and Find Full Text PDFVibrissal whisking is often employed to track facial nerve regeneration in rats; however, we have observed similar degrees of whisking recovery after facial nerve transection with or without repair. We hypothesized that the source of non-facial nerve-mediated whisker movement after chronic denervation was from autonomic, cholinergic axons traveling within the infraorbital branch of the trigeminal nerve (ION). Rats underwent unilateral facial nerve transection with repair (N=7) or resection without repair (N=11).
View Article and Find Full Text PDFA 50-year-old woman developed multiorgan system failure secondary to sepsis. She became obtunded during a period of hypotension, and cranial CT demonstrated diffuse borderzone infarction. Brain autopsy revealed green pigmentation in areas of infarction due to vascular leakage of bilirubin at sites of blood–brain barrier disruption, mapping the borderzone regions and bilateral anterior cerebral artery territories with this endogenous label (total bilirubin at time of death was 24 mg/dL; direct bilirubin 19 mg/dL) (figure).
View Article and Find Full Text PDFSolvent mapping moves molecular probes, small organic molecules containing various functional groups, around the protein surface, finds favorable positions, clusters the conformations, and ranks the clusters based on the average free energy. Using at least six different solvents as probes, the probes cluster in major pockets of the functional site, providing detailed and reliable information on the amino acid residues that are important for ligand binding. Solvent mapping was applied to 12 structures of the peroxisome proliferator activated receptor gamma (PPARgamma) ligand-binding domain (LBD), including 2 structures without a ligand, 2 structures with a partial agonist, and 8 structures with a PPAR agonist bound.
View Article and Find Full Text PDFPRECISE (Predicted and Consensus Interaction Sites in Enzymes) is a database of interactions between the amino acid residues of an enzyme and its ligands (substrate and transition state analogs, cofactors, inhibitors and products). It is available online at http://precise.bu.
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