scholarly journals Insights into calcium signaling and gene expression in astrocytes uncovered with 129S4 Slc1a3-2A-CreERT2 knock-in mice

2020 ◽  
Author(s):  
Lech Kaczmarczyk ◽  
Nicole Reichenbach ◽  
Nelli Blank ◽  
Maria Jonson ◽  
Lars Dittrich ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Phenotypic Diversity ◽  
Expression Patterns ◽  
Cell Types ◽  
Inbred Strains ◽  
Brain Regions ◽  
Genetically Engineered ◽  
Calcium Currents ◽  
Activity Levels ◽  
Genomic Locus

AbstractGenetic variation is a primary determinant of phenotypic diversity within populations. In laboratory mice, genetic variation has often been regarded as a serious experimental confounder, and thus minimized through inbreeding. However, generalizations of results obtained with inbred strains need to be made with caution. Effects of genetic background on traits need to be controlled, especially when working with complex phenotypes and disease models. Here we compared behavioral parameters of C57Bl/6 – the mouse strain most widely used for biomedical research - with those of 129S4. Our data demonstrate high within-strain and intra-litter behavioral hyperactivity in C57Bl/6. In contrast, 129S4 had relatively consistent activity levels throughout life. This consistency would be advantageous for studying neurodegeneration and aging, when mice need to be analyzed for long periods. However, the majority of mouse models and transgenic tools are on a C57Bl/6 background. We recently established six popular Cre driver lines and two Cre effector lines in 129S4. To augment this collection, we genetically engineered a Cre mouse line to study astrocytes directly in 129S4, which we describe here. For functional validation, it was crossed with two Cre effector lines, each in a different genomic locus, and showed in both cases that it was functional and astrocyte-specific. Calcium currents studied with gCaMP5g-tdTomato were more heterogenous, lasted longer and had a higher amplitude in cortical compared to hippocampal astrocytes. Translatomes studied with RiboTag revealed that some genes thought to mark neurons are also expressed in astrocytes, that genes linked to a single neurodegenerative disease have highly divergent expression patterns, and that ribosome proteins are non-uniformly expressed across brain regions and cell types.

scholarly journals Slc1a3-2A-CreERT2 mice reveal unique features of Bergmann glia and augment a growing collection of Cre drivers and effectors in the 129S4 genetic background

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lech Kaczmarczyk ◽  
Nicole Reichenbach ◽  
Nelli Blank ◽  
Maria Jonson ◽  
Lars Dittrich ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Phenotypic Diversity ◽  
Expression Patterns ◽  
Cell Types ◽  
Inbred Strains ◽  
Brain Regions ◽  
Genetically Engineered ◽  
Disease Models ◽  
Calcium Indicator ◽  
High Consistency

AbstractGenetic variation is a primary determinant of phenotypic diversity. In laboratory mice, genetic variation can be a serious experimental confounder, and thus minimized through inbreeding. However, generalizations of results obtained with inbred strains must be made with caution, especially when working with complex phenotypes and disease models. Here we compared behavioral characteristics of C57Bl/6—the strain most widely used in biomedical research—with those of 129S4. In contrast to 129S4, C57Bl/6 demonstrated high within-strain and intra-litter behavioral hyperactivity. Although high consistency would be advantageous, the majority of disease models and transgenic tools are in C57Bl/6. We recently established six Cre driver lines and two Cre effector lines in 129S4. To augment this collection, we genetically engineered a Cre line to study astrocytes in 129S4. It was validated with two Cre effector lines: calcium indicator gCaMP5g-tdTomato and RiboTag—a tool widely used to study cell type-specific translatomes. These reporters are in different genomic loci, and in both the Cre was functional and astrocyte-specific. We found that calcium signals lasted longer and had a higher amplitude in cortical compared to hippocampal astrocytes, genes linked to a single neurodegenerative disease have highly divergent expression patterns, and that ribosome proteins are non-uniformly expressed across brain regions and cell types.

scholarly journals Quantifying mechanisms in neurodegenerative diseases (NDDs) using candidate mechanism perturbation amplitude (CMPA) algorithm

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Reagon Karki ◽  
Alpha Tom Kodamullil ◽  
Charles Tapley Hoyt ◽  
Martin Hofmann-Apitius
Keyword(s):  
Biological Networks ◽  
Molecular Mechanisms ◽  
Biological Network ◽  
Expression Patterns ◽  
Cell Types ◽  
Brain Regions ◽  
Heat Diffusion ◽  
Disease Etiology ◽  
The Individual ◽  
Biological Entities

Abstract Background Literature derived knowledge assemblies have been used as an effective way of representing biological phenomenon and understanding disease etiology in systems biology. These include canonical pathway databases such as KEGG, Reactome and WikiPathways and disease specific network inventories such as causal biological networks database, PD map and NeuroMMSig. The represented knowledge in these resources delineates qualitative information focusing mainly on the causal relationships between biological entities. Genes, the major constituents of knowledge representations, tend to express differentially in different conditions such as cell types, brain regions and disease stages. A classical approach of interpreting a knowledge assembly is to explore gene expression patterns of the individual genes. However, an approach that enables quantification of the overall impact of differentially expressed genes in the corresponding network is still lacking. Results Using the concept of heat diffusion, we have devised an algorithm that is able to calculate the magnitude of regulation of a biological network using expression datasets. We have demonstrated that molecular mechanisms specific to Alzheimer (AD) and Parkinson Disease (PD) regulate with different intensities across spatial and temporal resolutions. Our approach depicts that the mitochondrial dysfunction in PD is severe in cortex and advanced stages of PD patients. Similarly, we have shown that the intensity of aggregation of neurofibrillary tangles (NFTs) in AD increases as the disease progresses. This finding is in concordance with previous studies that explain the burden of NFTs in stages of AD. Conclusions This study is one of the first attempts that enable quantification of mechanisms represented as biological networks. We have been able to quantify the magnitude of regulation of a biological network and illustrate that the magnitudes are different across spatial and temporal resolution.

scholarly journals Distinct properties in ventral pallidum projection neuron subtypes

2021 ◽  
Author(s):  
Nimrod Bernat ◽  
Rianne Campbell ◽  
Hyungwoo Nam ◽  
Mahashweta Basu ◽  
Tal Odesser ◽  
...  
Keyword(s):  
Gene Expression ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Critical Role ◽  
Gene Expression Profiles ◽  
Cell Types ◽  
Projection Neuron ◽  
Brain Regions ◽  
Ventral Pallidum ◽  
Lateral Habenula

The ventral pallidum (VP), a major component of the basal ganglia, plays a critical role in motivational disorders. It sends projections to many different brain regions but it is not yet known whether and how these projections differ in their cellular properties, gene expression patterns, connectivity and role in reward seeking. In this study, we focus on four major outputs of the VP - to the lateral hypothalamus (LH), ventral tegmental area (VTA), mediodorsal thalamus (MDT), and lateral habenula (LHb) - and examine the differences between them in 1) baseline gene expression profiles using projection-specific RNA-sequencing; 2) physiological parameters using whole-cell patch clamp; and 3) their influence on cocaine reward using chemogenetic tools. We show that these four VP efferents differ in all three aspects and highlight specifically differences between the projections to the LH and the VTA. These two projections originate largely from separate populations of neurons, express distinct sets of genes related to neurobiological functions, and show opposite physiological and behavioral properties. Collectively, our data demonstrates for the first time that VP neurons exhibit distinct molecular and cellular profiles in a projection-specific manner, suggesting that they represent different cell types.

scholarly journals Convergence Circuit Mapping: Genetic Approaches From Structure to Function

2021 ◽  
Vol 15 ◽  
Author(s):  
Jang Soo Yook ◽  
Jihyun Kim ◽  
Jinhyun Kim
Keyword(s):  
Fluorescent Proteins ◽  
Brain Activity ◽  
Molecular Genetic ◽  
Cell Types ◽  
Brain Regions ◽  
Genetically Engineered ◽  
Spatiotemporal Resolution ◽  
Genetic Switches ◽  
A Cell ◽  
And Behavior

Understanding the complex neural circuits that underpin brain function and behavior has been a long-standing goal of neuroscience. Yet this is no small feat considering the interconnectedness of neurons and other cell types, both within and across brain regions. In this review, we describe recent advances in mouse molecular genetic engineering that can be used to integrate information on brain activity and structure at regional, cellular, and subcellular levels. The convergence of structural inputs can be mapped throughout the brain in a cell type-specific manner by antero- and retrograde viral systems expressing various fluorescent proteins and genetic switches. Furthermore, neural activity can be manipulated using opto- and chemo-genetic tools to interrogate the functional significance of this input convergence. Monitoring neuronal activity is obtained with precise spatiotemporal resolution using genetically encoded sensors for calcium changes and specific neurotransmitters. Combining these genetically engineered mapping tools is a compelling approach for unraveling the structural and functional brain architecture of complex behaviors and malfunctioned states of neurological disorders.

Expression Pattern of the LacZ Reporter in Secretogranin III Gene-trapped Mice

2021 ◽  
Vol 69 (4) ◽  
pp. 229-243
Author(s):  
Hiroshi Gomi ◽  
Airi Hinata ◽  
Tadashi Yasui ◽  
Seiji Torii ◽  
Masahiro Hosaka
Keyword(s):  
Cell Function ◽  
Expression Patterns ◽  
Peptide Hormone ◽  
Cell Types ◽  
Brain Regions ◽  
Ependymal Cells ◽  
Lacz Reporter ◽  
Lacz Expression ◽  
Granule Formation ◽  
Gene Trapping

Secretogranin III (SgIII) is a granin protein involved in secretory granule formation in peptide-hormone-producing endocrine cells. In this study, we analyzed the expression of the LacZ reporter in the SgIII knockout mice produced by gene trapping ( SgIII-gtKO) for the purpose of comprehensively clarifying the expression patterns of SgIII at the cell and tissue levels. In the endocrine tissues of SgIII-gtKO mice, LacZ expression was observed in the pituitary gland, adrenal medulla, and pancreatic islets, where SgIII expression has been canonically revealed. LacZ expression was extensively observed in brain regions, especially in the cerebral cortex, hippocampus, hypothalamic nuclei, cerebellum, and spinal cord. In peripheral nervous tissues, LacZ expression was observed in the retina, optic nerve, and trigeminal ganglion. LacZ expression was particularly prominent in astrocytes, in addition to neurons and ependymal cells. In the cerebellum, at least four cell types expressed SgIII under basal conditions. The expression of SgIII in the glioma cell lines C6 and RGC-6 was enhanced by excitatory glutamate treatment. It also became clear that the expression level of SgIII varied among neuron and astrocyte subtypes. These results suggest that SgIII is involved in glial cell function, in addition to neuroendocrine functions, in the nervous system:

scholarly journals An atlas of cortical arealization identifies dynamic molecular signatures

Nature ◽  
2021 ◽  
Vol 598 (7879) ◽  
pp. 200-204
Author(s):  
Aparna Bhaduri ◽  
Carmen Sandoval-Espinosa ◽  
Marcos Otero-Garcia ◽  
Irene Oh ◽  
Raymund Yin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Single Molecule ◽  
Radial Glia ◽  
Expression Patterns ◽  
Brain Structures ◽  
Cell Types ◽  
Brain Regions ◽  
Cortical Areas ◽  
Spatial Differences ◽  
Cortical Regions

AbstractThe human brain is subdivided into distinct anatomical structures, including the neocortex, which in turn encompasses dozens of distinct specialized cortical areas. Early morphogenetic gradients are known to establish early brain regions and cortical areas, but how early patterns result in finer and more discrete spatial differences remains poorly understood1. Here we use single-cell RNA sequencing to profile ten major brain structures and six neocortical areas during peak neurogenesis and early gliogenesis. Within the neocortex, we find that early in the second trimester, a large number of genes are differentially expressed across distinct cortical areas in all cell types, including radial glia, the neural progenitors of the cortex. However, the abundance of areal transcriptomic signatures increases as radial glia differentiate into intermediate progenitor cells and ultimately give rise to excitatory neurons. Using an automated, multiplexed single-molecule fluorescent in situ hybridization approach, we find that laminar gene-expression patterns are highly dynamic across cortical regions. Together, our data suggest that early cortical areal patterning is defined by strong, mutually exclusive frontal and occipital gene-expression signatures, with resulting gradients giving rise to the specification of areas between these two poles throughout successive developmental timepoints.

scholarly journals Protein network analysis reveals selectively vulnerable regions and biological processes in FTD

2018 ◽  
Vol 4 (5) ◽  
pp. e266 ◽  
Author(s):  
Luke W. Bonham ◽  
Natasha Z.R. Steele ◽  
Celeste M. Karch ◽  
Claudia Manzoni ◽  
Ethan G. Geier ◽  
...  
Keyword(s):  
Association Studies ◽  
Expression Patterns ◽  
Interaction Network ◽  
Analytical Techniques ◽  
Cell Types ◽  
Brain Regions ◽  
Protein Network ◽  
Genome Wide Association Studies ◽  
Biological Processes ◽  
Human Brain Tissue

ObjectiveThe neuroanatomical profile of behavioral variant frontotemporal dementia (bvFTD) suggests a common biological etiology of disease despite disparate pathologic causes; we investigated the genetic underpinnings of this selective regional vulnerability to identify new risk factors for bvFTD.MethodsWe used recently developed analytical techniques designed to address the limitations of genome-wide association studies to generate a protein interaction network of 63 bvFTD risk genes. We characterized this network using gene expression data from healthy and diseased human brain tissue, evaluating regional network expression patterns across the lifespan as well as the cell types and biological processes most affected in bvFTD.ResultsWe found that bvFTD network genes show enriched expression across the human lifespan in vulnerable neuronal populations, are implicated in cell signaling, cell cycle, immune function, and development, and are differentially expressed in pathologically confirmed frontotemporal lobar degeneration cases. Five of the genes highlighted by our differential expression analyses, BAIAP2, ERBB3, POU2F2, SMARCA2, and CDC37, appear to be novel bvFTD risk loci.ConclusionsOur findings suggest that the cumulative burden of common genetic variation in an interacting protein network expressed in specific brain regions across the lifespan may influence susceptibility to bvFTD.

scholarly journals Mechanisms underlying divergent responses of genetically distinct macrophages to IL-4

2020 ◽  
Author(s):  
Marten A. Hoeksema ◽  
Zeyang Shen ◽  
Inge R. Holtman ◽  
An Zheng ◽  
Nathan Spann ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genetic Variation ◽  
Disease Risk ◽  
Phenotypic Diversity ◽  
Inbred Strains ◽  
Dynamic Responses ◽  
Interleukin 4 ◽  
Enhancer Activity ◽  
Inbred Strains Of Mice ◽  
Mutation Analyses

AbstractMechanisms by which non-coding genetic variation influences gene expression remain only partially understood but are considered to be major determinants of phenotypic diversity and disease risk. Here, we evaluated effects of >50 million SNPs and InDels provided by five inbred strains of mice on the responses of macrophages to interleukin 4 (IL-4), a cytokine that plays pleiotropic roles in immunity and tissue homeostasis. Remarkably, of >600 genes induced >2-fold by IL-4 across the five strains, only 26 genes reached this threshold in all strains. By applying deep learning and motif mutation analyses to epigenetic data for macrophages from each strain, we identified the dominant combinations of lineage determining and signal-dependent transcription factors driving late enhancer activation. These studies further revealed mechanisms by which non-coding genetic variation influences absolute levels of enhancer activity and their dynamic responses to IL-4, thereby contributing to strain-differential patterns of gene expression and phenotypic diversity.

scholarly journals An Atlas of Cortical Arealization Identifies Dynamic Molecular Signatures

2021 ◽  
Author(s):  
Aparna Bhaduri ◽  
Carmen Sandoval-Espinosa ◽  
Marcos Otero-Garcia ◽  
Irena Oh ◽  
Raymund Yin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Human Brain ◽  
Single Molecule ◽  
Radial Glia ◽  
Expression Patterns ◽  
Brain Structures ◽  
Cell Types ◽  
Brain Regions ◽  
Cortical Areas ◽  
Cortical Regions

The human brain is subdivided into distinct anatomical structures. The neocortex, one of these structures, enables higher-order sensory, associative, and cognitive functions, and in turn encompasses dozens of distinct specialized cortical areas. Early morphogenetic gradients are known to establish an early blueprint for the specification of brain regions and cortical areas. Furthermore, recent studies have uncovered distinct transcriptomic signatures between opposing poles of the developing neocortex1. However, how early, broad developmental patterns result in finer and more discrete spatial differences across the adult human brain remains poorly understood2. Here, we use single-cell RNA-sequencing to profile ten major brain structures and six neocortical areas during peak neurogenesis and early gliogenesis. Our data reveal that distinct cell subtypes are predominantly brain-structure specific. Within the neocortex, we find that even early in the second trimester, a large number of genes are differentially expressed across distinct cortical areas in all cell types, including radial glia, the neural progenitors of the cortex. However, the abundance of areal transcriptomic signatures increases as radial glia differentiate into intermediate progenitor cells and ultimately give rise to excitatory neurons. Using an automated, multiplexed single-molecule fluorescent in situ hybridization (smFISH) approach, we validated the expression pattern of area-specific neuronal genes and also discover that laminar gene expression patterns are highly dynamic across cortical regions. Together, our data suggest that early cortical areal patterning is defined by strong, mutually exclusive frontal and occipital gene expression signatures, with resulting gradients giving rise to the specification of areas between these two poles throughout successive developmental timepoints.

scholarly journals Mechanisms underlying divergent responses of genetically distinct macrophages to IL-4

2021 ◽  
Vol 7 (25) ◽  
pp. eabf9808
Author(s):  
Marten A. Hoeksema ◽  
Zeyang Shen ◽  
Inge R. Holtman ◽  
An Zheng ◽  
Nathan J. Spann ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genetic Variation ◽  
Disease Risk ◽  
Phenotypic Diversity ◽  
Inbred Strains ◽  
Dynamic Responses ◽  
Interleukin 4 ◽  
Nucleotide Polymorphisms ◽  
Enhancer Activity ◽  
Inbred Strains Of Mice

Mechanisms by which noncoding genetic variation influences gene expression remain only partially understood but are considered to be major determinants of phenotypic diversity and disease risk. Here, we evaluated effects of >50 million single-nucleotide polymorphisms and short insertions/deletions provided by five inbred strains of mice on the responses of macrophages to interleukin-4 (IL-4), a cytokine that plays pleiotropic roles in immunity and tissue homeostasis. Of >600 genes induced >2-fold by IL-4 across the five strains, only 26 genes reached this threshold in all strains. By applying deep learning and motif mutation analyses to epigenetic data for macrophages from each strain, we identified the dominant combinations of lineage-determining and signal-dependent transcription factors driving IL-4 enhancer activation. These studies further revealed mechanisms by which noncoding genetic variation influences absolute levels of enhancer activity and their dynamic responses to IL-4, thereby contributing to strain-differential patterns of gene expression and phenotypic diversity.

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