ABSTRACT
Microglia play a key role in shaping the formation and refinement of the excitatory network of the brain. However, less is known about whether and how they organize the development of distinct inhibitory networks. We find that microglia are essential for the proper development of somatostatin-positive (SST+) cell synapses during the second postnatal week. We further identify a pair of molecules that act antagonistically to one another in the organization of SST+ cell axonal elaboration. Whereas CX3CL1 acts to suppress axonal growth and complexity, CXCL12 promotes it. Assessing the functional importance of microglia in the development of cortical activity, we find that a whisker stimulation paradigm that drives SST+ cell activation leads to reduced cortical spiking in brains depleted of microglia. Collectively, our data demonstrate an important role of microglia in regulating the development of SST+ cell output early in life.
Subject(s)
Interneurons , Vibrissae , Animals , Interneurons/physiology , Microglia , Somatostatin , Synapses/physiologyABSTRACT
Human organoids recapitulating the cell-type diversity and function of their target organ are valuable for basic and translational research. We developed light-sensitive human retinal organoids with multiple nuclear and synaptic layers and functional synapses. We sequenced the RNA of 285,441 single cells from these organoids at seven developmental time points and from the periphery, fovea, pigment epithelium and choroid of light-responsive adult human retinas, and performed histochemistry. Cell types in organoids matured in vitro to a stable "developed" state at a rate similar to human retina development in vivo. Transcriptomes of organoid cell types converged toward the transcriptomes of adult peripheral retinal cell types. Expression of disease-associated genes was cell-type-specific in adult retina, and cell-type specificity was retained in organoids. We implicate unexpected cell types in diseases such as macular degeneration. This resource identifies cellular targets for studying disease mechanisms in organoids and for targeted repair in human retinas.
Subject(s)
Cell Differentiation/genetics , Organoids/cytology , Organoids/metabolism , Retina/cytology , Retina/metabolism , Single-Cell Analysis/methods , Synapses/physiology , Transcriptome/genetics , Cell Culture Techniques/methods , Cell Line , Electrophysiology , Female , Gene Expression Regulation, Developmental/genetics , Genetic Predisposition to Disease/genetics , Humans , In Situ Hybridization , Induced Pluripotent Stem Cells/cytology , Induced Pluripotent Stem Cells/metabolism , Microscopy, Electron , Multigene Family , Naphthoquinones , Organoids/radiation effects , Organoids/ultrastructure , Retina/pathology , Retina/radiation effectsABSTRACT
N-demethylation of N,N-dimethylanilines promoted by [(N4Py)Fe(IV)=O](2+) occurs by an electron transfer-proton transfer (ET-PT) mechanism with a rate determining PT step. From the bell-shaped curve of the KDIE profile it has been estimated that the pK(a) of [(N4Py)Fe(III)-OH](2+) is 9.7.
