scholarly journals Control of synaptic specificity by limiting promiscuous synapse formation

2018 ◽  
Author(s):  
Chundi Xu ◽  
Emma Theisen ◽  
Elijah Rumbaut ◽  
Bryan Shum ◽  
Jing Peng ◽  
...  
Keyword(s):  
Visual System ◽  
Synapse Formation ◽  
Neural Circuits ◽  
Local Environment ◽  
Cell Types ◽  
Partner Choice ◽  
Synaptic Connectivity ◽  
Specific Cell ◽  
Synaptic Specificity ◽  
And Function

SUMMARYThe ability of neurons to distinguish appropriate from inappropriate synaptic partners in their local environment is fundamental to the proper assembly and function of neural circuits. How synaptic partner selection is regulated is a longstanding question in Neurobiology. A prevailing hypothesis is that appropriate partners express complementary molecules that match them together and promote synaptogenesis. Dpr and DIP IgSF proteins bind heterophilically and are expressed in a complementary manner between synaptic partners in the Drosophila visual system. Here, we show that in the lamina, DIP mis-expression is sufficient to promote synapse formation with Dpr-expressing neurons, and that DIP proteins are not necessary for synaptogenesis but rather function to prevent ectopic synapse formation. These findings indicate that Dpr-DIP interactions regulate synaptic specificity by biasing synapse formation towards specific cell-types. We propose that synaptogenesis occurs independent of synaptic partner choice, and that precise synaptic connectivity is established by limiting promiscuous synapse formation.

scholarly journals Epigenetic reprogramming of cell identity: lessons from development for regenerative medicine

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Amitava Basu ◽  
Vijay K. Tiwari
Keyword(s):  
Regenerative Medicine ◽  
Cell Types ◽  
Direct Conversion ◽  
Cellular Reprogramming ◽  
Specific Cell ◽  
Cell Type ◽  
Pathological Conditions ◽  
Gene Regulatory ◽  
Induced Pluripotent ◽  
And Function

AbstractEpigenetic mechanisms are known to define cell-type identity and function. Hence, reprogramming of one cell type into another essentially requires a rewiring of the underlying epigenome. Cellular reprogramming can convert somatic cells to induced pluripotent stem cells (iPSCs) that can be directed to differentiate to specific cell types. Trans-differentiation or direct reprogramming, on the other hand, involves the direct conversion of one cell type into another. In this review, we highlight how gene regulatory mechanisms identified to be critical for developmental processes were successfully used for cellular reprogramming of various cell types. We also discuss how the therapeutic use of the reprogrammed cells is beginning to revolutionize the field of regenerative medicine particularly in the repair and regeneration of damaged tissue and organs arising from pathological conditions or accidents. Lastly, we highlight some key challenges hindering the application of cellular reprogramming for therapeutic purposes.

scholarly journals Developmental enhancers and chromosome topology

Science ◽  
2018 ◽  
Vol 361 (6409) ◽  
pp. 1341-1345 ◽  
Author(s):  
Eileen E. M. Furlong ◽  
Michael Levine
Keyword(s):  
Three Dimensional ◽  
Cell Types ◽  
Living Cells ◽  
Specific Cell ◽  
Transcriptional Dynamics ◽  
Spatiotemporal Expression ◽  
Chromosome Topology ◽  
Classical Models ◽  
And Function ◽  
Target Promoters

Developmental enhancers mediate on/off patterns of gene expression in specific cell types at particular stages during metazoan embryogenesis. They typically integrate multiple signals and regulatory determinants to achieve precise spatiotemporal expression. Such enhancers can map quite far—one megabase or more—from the genes they regulate. How remote enhancers relay regulatory information to their target promoters is one of the central mysteries of genome organization and function. A variety of contrasting mechanisms have been proposed over the years, including enhancer tracking, linking, looping, and mobilization to transcription factories. We argue that extreme versions of these mechanisms cannot account for the transcriptional dynamics and precision seen in living cells, tissues, and embryos. We describe emerging evidence for dynamic three-dimensional hubs that combine different elements of the classical models.

scholarly journals Single cell analysis reveals immune cell–adipocyte crosstalk regulating the transcription of thermogenic adipocytes

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Prashant Rajbhandari ◽  
Douglas Arneson ◽  
Sydney K Hart ◽  
In Sook Ahn ◽  
Graciel Diamante ◽  
...  
Keyword(s):  
Single Cell ◽  
Immune Cells ◽  
Immune Cell ◽  
Single Cell Analysis ◽  
Metabolic Response ◽  
Cell Types ◽  
Specific Cell ◽  
Beneficial Effects ◽  
Thermogenic Adipocytes ◽  
And Function

Immune cells are vital constituents of the adipose microenvironment that influence both local and systemic lipid metabolism. Mice lacking IL10 have enhanced thermogenesis, but the roles of specific cell types in the metabolic response to IL10 remain to be defined. We demonstrate here that selective loss of IL10 receptor α in adipocytes recapitulates the beneficial effects of global IL10 deletion, and that local crosstalk between IL10-producing immune cells and adipocytes is a determinant of thermogenesis and systemic energy balance. Single Nuclei Adipocyte RNA-sequencing (SNAP-seq) of subcutaneous adipose tissue defined a metabolically-active mature adipocyte subtype characterized by robust expression of genes involved in thermogenesis whose transcriptome was selectively responsive to IL10Rα deletion. Furthermore, single-cell transcriptomic analysis of adipose stromal populations identified lymphocytes as a key source of IL10 production in response to thermogenic stimuli. These findings implicate adaptive immune cell-adipocyte communication in the maintenance of adipose subtype identity and function.

scholarly journals Cellular Circuits in the Brain and Their Modulation in Acute and Chronic Pain

2021 ◽  
Vol 101 (1) ◽  
pp. 213-258 ◽  
Author(s):  
Rohini Kuner ◽  
Thomas Kuner
Keyword(s):  
Chronic Pain ◽  
Neural Circuits ◽  
Cell Types ◽  
Mammalian Brain ◽  
Specific Cell ◽  
Dynamic Regulation ◽  
Maladaptive Plasticity ◽  
Pathological Pain ◽  
Dimensions Of Pain ◽  
Cellular Circuits

Chronic, pathological pain remains a global health problem and a challenge to basic and clinical sciences. A major obstacle to preventing, treating, or reverting chronic pain has been that the nature of neural circuits underlying the diverse components of the complex, multidimensional experience of pain is not well understood. Moreover, chronic pain involves diverse maladaptive plasticity processes, which have not been decoded mechanistically in terms of involvement of specific circuits and cause-effect relationships. This review aims to discuss recent advances in our understanding of circuit connectivity in the mammalian brain at the level of regional contributions and specific cell types in acute and chronic pain. A major focus is placed on functional dissection of sub-neocortical brain circuits using optogenetics, chemogenetics, and imaging technological tools in rodent models with a view towards decoding sensory, affective, and motivational-cognitive dimensions of pain. The review summarizes recent breakthroughs and insights on structure-function properties in nociceptive circuits and higher order sub-neocortical modulatory circuits involved in aversion, learning, reward, and mood and their modulation by endogenous GABAergic inhibition, noradrenergic, cholinergic, dopaminergic, serotonergic, and peptidergic pathways. The knowledge of neural circuits and their dynamic regulation via functional and structural plasticity will be beneficial towards designing and improving targeted therapies.

Cementum and Periodontal Wound Healing and Regeneration

2002 ◽  
Vol 13 (6) ◽  
pp. 474-484 ◽  
Author(s):  
Wojciech J. Grzesik ◽  
A.S. Narayanan
Keyword(s):  
Structural Integrity ◽  
Periodontal Regeneration ◽  
Local Environment ◽  
Cell Types ◽  
Wound Matrix ◽  
Mineralized Tissues ◽  
And Function ◽  
Regenerative Therapies ◽  
Periodontal Wound Healing ◽  
Periodontal Healing

The extracellular matrix (ECM) of cementum resembles other mineralized tissues in composition; however, its physiology is unique, and it contains molecules that have not been detected in other tissues. Cementum components influence the activities of periodontal cells, and they manifest selectivity toward some periodontal cell types over others. In light of emerging evidence that the ECM determines how cells respond to environmental stimuli, we hypothesize that the local environment of the cementum matrix plays a pivotal role in maintaining the homeostasis of cementum under healthy conditions. The structural integrity and biochemical composition of the cementum matrix are severely compromised in periodontal disease, and the provisional matrix generated during periodontal healing is different from that of cementum. We propose that, for new cementum and attachment formation during periodontal regeneration, the local environment must be conducive for the recruitment and function of cementum-forming cells, and that the wound matrix is favorable for repair rather than regeneration. How cementum components may regulate and participate in cementum regeneration, possible new regenerative therapies using these principles, and models of cementoblastic cells are discussed.

scholarly journals Adeno-Associated Virus Technologies and Methods for Targeted Neuronal Manipulation

2019 ◽  
Author(s):  
Leila Haery ◽  
Benjamin E. Deverman ◽  
Katherine Matho ◽  
Ali Cetin ◽  
Kenton Woodard ◽  
...  
Keyword(s):  
Viral Vectors ◽  
Cell Types ◽  
Regulatory Elements ◽  
Specific Cell ◽  
Specific Expression ◽  
Adeno Associated Virus ◽  
Cell Type Specific Expression ◽  
Cell Type Specific ◽  
And Function ◽  
Novel Applications

AbstractCell-type-specific expression of molecular tools and sensors is critical to construct circuit diagrams and to investigate the activity and function of neurons within the nervous system. Strategies for targeted manipulation include combinations of classical genetic tools such as Cre/loxP and Flp/FRT, use of cis-regulatory elements, targeted knock-in transgenic mice, and gene delivery by AAV and other viral vectors. The combination of these complex technologies with the goal of precise neuronal targeting is a challenge in the lab. This report will discuss the theoretical and practical aspects of combining current technologies and establish best practices for achieving targeted manipulation of specific cell types. Novel applications and tools, as well as areas for development, will be envisioned and discussed.

scholarly journals Controlled Signaling—Insulin-Like Growth Factor Receptor Endocytosis and Presence at Intracellular Compartments

2021 ◽  
Vol 11 ◽  
Author(s):  
Leonie Rieger ◽  
Rosemary O’Connor
Keyword(s):  
Golgi Apparatus ◽  
Cancer Cells ◽  
Growth Factor Receptor ◽  
Cell Types ◽  
Specific Cell ◽  
Receptor Endocytosis ◽  
Intracellular Compartments ◽  
Associated Proteins ◽  
Membrane Compartments ◽  
And Function

Ligand-induced activation of the IGF-1 receptor triggers plasma-membrane-derived signal transduction but also triggers receptor endocytosis, which was previously thought to limit signaling. However, it is becoming ever more clear that IGF-1R endocytosis and trafficking to specific subcellular locations can define specific signaling responses that are important for key biological processes in normal cells and cancer cells. In different cell types, specific cell adhesion receptors and associated proteins can regulate IGF-1R endocytosis and trafficking. Once internalized, the IGF-1R may be recycled, degraded or translocated to the intracellular membrane compartments of the Golgi apparatus or the nucleus. The IGF-1R is present in the Golgi apparatus of migratory cancer cells where its signaling contributes to aggressive cancer behaviors including cell migration. The IGF-1R is also found in the nucleus of certain cancer cells where it can regulate gene expression. Nuclear IGF-1R is associated with poor clinical outcomes. IGF-1R signaling has also been shown to support mitochondrial biogenesis and function, and IGF-1R inhibition causes mitochondrial dysfunction. How IGF-1R intracellular trafficking and compartmentalized signaling is controlled is still unknown. This is an important area for further study, particularly in cancer.

scholarly journals High Resolution Single Cell Maps Reveals Distinct Cell Organization and Function Across Different Regions of the Human Intestine

2021 ◽  
Author(s):  
John W Hickey ◽  
Winston R Becker ◽  
Stephanie A Nevins ◽  
Aaron M Horning ◽  
Almudena Espin Perez ◽  
...  
Keyword(s):  
Single Cell ◽  
Immune Surveillance ◽  
Cell Types ◽  
Open Chromatin ◽  
Specific Cell ◽  
Symbiotic Relationships ◽  
Distinct Cell ◽  
Cell Organization ◽  
Reference Map ◽  
And Function

The colon is a complex organ that promotes digestion, extracts nutrients, participates in immune surveillance, maintains critical symbiotic relationships with microbiota, and affects overall health. To better understand its organization, functions, and its regulation at a single cell level, we performed CODEX multiplexed imaging, as well as single nuclear RNA and open chromatin assays across eight different intestinal sites of four donors. Through systematic analyses we find cell compositions differ dramatically across regions of the intestine, demonstrate the complexity of epithelial subtypes, and find that the same cell types are organized into distinct neighborhoods and communities highlighting distinct immunological niches present in the intestine. We also map gene regulatory differences in these cells suggestive of a regulatory differentiation cascade, and associate intestinal disease heritability with specific cell types. These results describe the complexity of the cell composition, regulation, and organization for this organ, and serve as an important reference map for understanding human biology and disease.

scholarly journals Purα Is Essential for Postnatal Brain Development and Developmentally Coupled Cellular Proliferation As Revealed by Genetic Inactivation in the Mouse

2003 ◽  
Vol 23 (19) ◽  
pp. 6857-6875 ◽  
Author(s):  
Kamel Khalili ◽  
Luis Del Valle ◽  
Vandhana Muralidharan ◽  
William J. Gault ◽  
Nune Darbinian ◽  
...  
Keyword(s):  
Dna Replication ◽  
Cellular Proliferation ◽  
Rna Binding ◽  
Synapse Formation ◽  
Critical Time ◽  
Immunohistochemical Analysis ◽  
Cell Types ◽  
Specific Cell ◽  
Rna Transport ◽  
Protein Marker

ABSTRACT The single-stranded DNA- and RNA-binding protein, Purα, has been implicated in many biological processes, including control of transcription of multiple genes, initiation of DNA replication, and RNA transport and translation. Deletions of the PURA gene are frequent in acute myeloid leukemia. Mice with targeted disruption of the PURA gene in both alleles appear normal at birth, but at 2 weeks of age, they develop neurological problems manifest by severe tremor and spontaneous seizures and they die by 4 weeks. There are severely lower numbers of neurons in regions of the hippocampus and cerebellum of PURA−/− mice versus those of age-matched +/+ littermates, and lamination of these regions is aberrant at time of death. Immunohistochemical analysis of MCM7, a protein marker for DNA replication, reveals a lack of proliferation of precursor cells in these regions in the PURA−/− mice. Levels of proliferation were also absent or low in several other tissues of the PURA−/− mice, including those of myeloid lineage, whereas those of PURA+/− mice were intermediate. Evaluation of brain sections indicates a reduction in myelin and glial fibrillary acidic protein labeling in oligodendrocytes and astrocytes, respectively, indicating pathological development of these cells. At postnatal day 5, a critical time for cerebellar development, Purα and Cdk5 were both at peak levels in bodies and dendrites of Purkinje cells of PURA+/+ mice, but both were absent in dendrites of PURA−/− mice. Purα and Cdk5 can be coimmunoprecipitated from brain lysates of PURA+/+ mice. Immunohistochemical studies reveal a dramatic reduction in the level of both phosphorylated and nonphosphorylated neurofilaments in dendrites of the Purkinje cell layer and of synapse formation in the hippocampus. Overall results are consistent with a role for Purα in developmentally timed DNA replication in specific cell types and also point to a newly emerging role in compartmentalized RNA transport and translation in neuronal dendrites.

scholarly journals Anterograde Trans-Synaptic AAV Strategies for Probing Neural Circuitry

2019 ◽  
Author(s):  
Brian Zingg ◽  
Bo Peng ◽  
Junxiang J. Huang ◽  
Huizhong W. Tao ◽  
Li I. Zhang
Keyword(s):  
Neural Circuits ◽  
Brain Regions ◽  
Inhibitory Neurons ◽  
Long Distance ◽  
Adeno Associated Virus ◽  
Spinal Cord Neurons ◽  
Synaptic Specificity ◽  
Molecular Approaches ◽  
Gabaergic Synapses ◽  
And Function

SummaryElucidating the organization and function of neural circuits is greatly facilitated by viral tools that spread transsynaptically. Adeno-associated virus (AAV) has been shown to exhibit anterograde transneuronal spread. However, the synaptic specificity of the spread and its broad application in various neural circuits remain to be explored. Here, using anatomical, functional, and molecular approaches, we provide strong evidence for the specifically preferential spread of AAV1 to post-synaptically connected neurons. Besides glutamatergic synapses made onto excitatory and inhibitory neurons, AAV1 also transsynaptically spreads through GABAergic synapses and effectively tags spinal cord neurons receiving long-distance projections from various brain regions, but exhibits little or no spread through neuromodulatory projections (e.g. serotonergic, cholinergic, and noradrenergic). Combined with newly designed intersectional and sparse labeling strategies, AAV1 can be utilized to categorize neurons according to their input sources, morphological and molecular identities. These properties make AAV a unique anterograde transsynaptic tool for establishing a comprehensive cell-atlas of the brain.

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