RESUMO
The specification of synaptic properties is fundamental for the function of neuronal circuits. "Terminal selector" transcription factors coordinate terminal gene batteries that specify cell-type-specific properties. Moreover, pan-neuronal splicing regulators have been implicated in directing neuronal differentiation. However, the cellular logic of how splicing regulators instruct specific synaptic properties remains poorly understood. Here, we combine genome-wide mapping of mRNA targets and cell-type-specific loss-of-function studies to uncover the contribution of the RNA-binding protein SLM2 to hippocampal synapse specification. Focusing on pyramidal cells and somatostatin (SST)-positive GABAergic interneurons, we find that SLM2 preferentially binds and regulates alternative splicing of transcripts encoding synaptic proteins. In the absence of SLM2, neuronal populations exhibit normal intrinsic properties, but there are non-cell-autonomous synaptic phenotypes and associated defects in a hippocampus-dependent memory task. Thus, alternative splicing provides a critical layer of gene regulation that instructs specification of neuronal connectivity in a trans-synaptic manner.
Assuntos
Processamento Alternativo , Neurônios , Processamento Alternativo/genética , Neurônios/metabolismo , Sinapses/metabolismo , Células Piramidais , Interneurônios , Hipocampo/metabolismoRESUMO
The Cre-loxP system is invaluable for spatial and temporal control of gene knockout, knockin, and reporter expression in the mouse nervous system. However, we report varying probabilities of unexpected germline recombination in distinct Cre driver lines designed for nervous system-specific recombination. Selective maternal or paternal germline recombination is showcased with sample Cre lines. Collated data reveal germline recombination in over half of 64 commonly used Cre driver lines, in most cases with a parental sex bias related to Cre expression in sperm or oocytes. Slight differences among Cre driver lines utilizing common transcriptional control elements affect germline recombination rates. Specific target loci demonstrated differential recombination; thus, reporters are not reliable proxies for another locus of interest. Similar principles apply to other recombinase systems and other genetically targeted organisms. We hereby draw attention to the prevalence of germline recombination and provide guidelines to inform future research for the neuroscience and broader molecular genetics communities.
Assuntos
Marcação de Genes/métodos , Integrases/genética , Neurônios/metabolismo , Oócitos/metabolismo , Recombinação Genética/genética , Espermatozoides/metabolismo , Animais , Feminino , Genes Reporter , Células Germinativas , Masculino , Camundongos , Camundongos Transgênicos , MosaicismoRESUMO
Nervous system function relies on complex assemblies of distinct neuronal cell types that have unique anatomical and functional properties instructed by molecular programs. Alternative splicing is a key mechanism for the expansion of molecular repertoires, and protein splice isoforms shape neuronal cell surface recognition and function. However, the logic of how alternative splicing programs are arrayed across neuronal cells types is poorly understood. We systematically mapped ribosome-associated transcript isoforms in genetically defined neuron types of the mouse forebrain. Our dataset provides an extensive resource of transcript diversity across major neuron classes. We find that neuronal transcript isoform profiles reliably distinguish even closely related classes of pyramidal cells and inhibitory interneurons in the mouse hippocampus and neocortex. These highly specific alternative splicing programs selectively control synaptic proteins and intrinsic neuronal properties. Thus, transcript diversification via alternative splicing is a central mechanism for the functional specification of neuronal cell types and circuits.
Assuntos
Processamento Alternativo/genética , Neurônios/fisiologia , Ribossomos/genética , Transcrição Gênica/genética , Animais , Células Cultivadas , Feminino , Regulação da Expressão Gênica/genética , Hipocampo/citologia , Interneurônios/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neocórtex/citologia , Neurônios/classificação , Terminações Pré-Sinápticas/metabolismo , Prosencéfalo/citologia , Isoformas de Proteínas/genética , Células Piramidais/fisiologiaRESUMO
Posttranscriptional mechanisms provide powerful means to expand the coding power of genomes. In nervous systems, alternative splicing has emerged as a fundamental mechanism not only for the diversification of protein isoforms but also for the spatiotemporal control of transcripts. Thus, alternative splicing programs play instructive roles in the development of neuronal cell type-specific properties, neuronal growth, self-recognition, synapse specification, and neuronal network function. Here we discuss the most recent genome-wide efforts on mapping RNA codes and RNA-binding proteins for neuronal alternative splicing regulation. We illustrate how alternative splicing shapes key steps of neuronal development, neuronal maturation, and synaptic properties. Finally, we highlight efforts to dissect the spatiotemporal dynamics of alternative splicing and their potential contribution to neuronal plasticity and the mature nervous system.
Assuntos
Processamento Alternativo/genética , Diferenciação Celular/genética , Plasticidade Neuronal/genética , Neurônios/metabolismo , Humanos , Neurogênese/genética , Neurônios/citologia , Isoformas de Proteínas/genética , RNA/genética , Proteínas de Ligação a RNA/genética , Sinapses/genéticaRESUMO
Regulation of neurotransmitter receptor localization is critical for synaptic function and plasticity. In this issue of Neuron, Matsuda and colleagues (Matsuda et al., 2016) uncover a transsynaptic complex consisting of neurexin-3, C1q-like proteins, and kainate receptors that drives glutamate receptor clustering at hippocampal synapses.
