1
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Mondal S, Becskei A. Gene choice in cancer cells is exclusive in ion transport but concurrent in DNA replication. Comput Struct Biotechnol J 2024; 23:2534-2547. [PMID: 38974885 PMCID: PMC11226983 DOI: 10.1016/j.csbj.2024.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/04/2024] [Accepted: 06/04/2024] [Indexed: 07/09/2024] Open
Abstract
Cancers share common cellular and physiological features. Little is known about whether distinctive gene expression patterns can be displayed at the single-cell level by gene families in cancer cells. The expression of gene homologs within a family can exhibit concurrence and exclusivity. Concurrence can promote all-or-none expression patterns of related genes and underlie alternative physiological states. Conversely, exclusive gene families express the same or similar number of homologs in each cell, allowing a broad repertoire of cell identities to be generated. We show that gene families involved in the cell-cycle and antigen presentation are expressed concurrently. Concurrence in the DNA replication complex MCM reflects the replicative status of cells, including cell lines and cancer-derived organoids. Exclusive expression requires precise regulatory mechanism, but cancer cells retain this form of control for ion homeostasis and extend it to gene families involved in cell migration. Thus, the cell adhesion-based identity of healthy cells is transformed to an identity based on migration in the population of cancer cells, reminiscent of epithelial-mesenchymal transition.
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Affiliation(s)
- Samuel Mondal
- Biozentrum, University of Basel, Spitalstrasse 41, Basel 4056, Switzerland
| | - Attila Becskei
- Biozentrum, University of Basel, Spitalstrasse 41, Basel 4056, Switzerland
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2
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Zhu YJ, Deng CY, Fan L, Wang YQ, Zhou H, Xu HT. Combinatorial expression of γ-protocadherins regulates synaptic connectivity in the mouse neocortex. eLife 2024; 12:RP89532. [PMID: 38470230 DOI: 10.7554/elife.89532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024] Open
Abstract
In the process of synaptic formation, neurons must not only adhere to specific principles when selecting synaptic partners but also possess mechanisms to avoid undesirable connections. Yet, the strategies employed to prevent unwarranted associations have remained largely unknown. In our study, we have identified the pivotal role of combinatorial clustered protocadherin gamma (γ-PCDH) expression in orchestrating synaptic connectivity in the mouse neocortex. Through 5' end single-cell sequencing, we unveiled the intricate combinatorial expression patterns of γ-PCDH variable isoforms within neocortical neurons. Furthermore, our whole-cell patch-clamp recordings demonstrated that as the similarity in this combinatorial pattern among neurons increased, their synaptic connectivity decreased. Our findings elucidate a sophisticated molecular mechanism governing the construction of neural networks in the mouse neocortex.
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Affiliation(s)
- Yi-Jun Zhu
- Institute of Neuroscience and State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
- Lingang Laboratory, Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Cai-Yun Deng
- Institute of Neuroscience and State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Liu Fan
- Lingang Laboratory, Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
| | - Ya-Qian Wang
- Lingang Laboratory, Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
| | - Hui Zhou
- Lingang Laboratory, Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
| | - Hua-Tai Xu
- Institute of Neuroscience and State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
- Lingang Laboratory, Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
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3
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Mañes-García J, Marco-Ferreres R, Beccari L. Shaping gene expression and its evolution by chromatin architecture and enhancer activity. Curr Top Dev Biol 2024; 159:406-437. [PMID: 38729683 DOI: 10.1016/bs.ctdb.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024]
Abstract
Transcriptional regulation plays a pivotal role in orchestrating the intricate genetic programs governing embryonic development. The expression of developmental genes relies on the combined activity of several cis-regulatory elements (CREs), such as enhancers and silencers, which can be located at long linear distances from the genes that they regulate and that interact with them through establishment of chromatin loops. Mutations affecting their activity or interaction with their target genes can lead to developmental disorders and are thought to have importantly contributed to the evolution of the animal body plan. The income of next-generation-sequencing approaches has allowed identifying over a million of sequences with putative regulatory potential in the human genome. Characterizing their function and establishing gene-CREs maps is essential to decode the logic governing developmental gene expression and is one of the major challenges of the post-genomic era. Chromatin 3D organization plays an essential role in determining how CREs specifically contact their target genes while avoiding deleterious off-target interactions. Our understanding of these aspects has greatly advanced with the income of chromatin conformation capture techniques and fluorescence microscopy approaches to visualize the organization of DNA elements in the nucleus. Here we will summarize relevant aspects of how the interplay between CRE activity and chromatin 3D organization regulates developmental gene expression and how it relates to pathological conditions and the evolution of animal body plan.
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Affiliation(s)
| | | | - Leonardo Beccari
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain.
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4
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Pechmann S. Single-cell expression predicts neuron-specific protein homeostasis networks. Open Biol 2024; 14:230386. [PMID: 38262604 PMCID: PMC10805596 DOI: 10.1098/rsob.230386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 11/17/2023] [Indexed: 01/25/2024] Open
Abstract
The protein homeostasis network keeps proteins in their correct shapes and avoids unwanted aggregation. In turn, the accumulation of aberrantly misfolded proteins has been directly associated with the onset of ageing-associated neurodegenerative diseases such as Alzheimer's and Parkinson's. However, a detailed and rational understanding of how protein homeostasis is achieved in health, and how it can be targeted for therapeutic intervention in diseases remains missing. Here, large-scale single-cell expression data from the Allen Brain Map are analysed to investigate the transcription regulation of the core protein homeostasis network across the human brain. Remarkably, distinct expression profiles suggest specialized protein homeostasis networks with systematic adaptations in excitatory neurons, inhibitory neurons and non-neuronal cells. Moreover, several chaperones and Ubiquitin ligases are found transcriptionally coregulated with genes important for synapse formation and maintenance, thus linking protein homeostasis to the regulation of neuronal function. Finally, evolutionary analyses highlight the conservation of an elevated interaction density in the chaperone network, suggesting that one of the most exciting aspects of chaperone action may yet be discovered in their collective action at the systems level. More generally, our work highlights the power of computational analyses for breaking down complexity and gaining complementary insights into fundamental biological problems.
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5
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Becskei A, Rahaman S. The life and death of RNA across temperatures. Comput Struct Biotechnol J 2022; 20:4325-4336. [PMID: 36051884 PMCID: PMC9411577 DOI: 10.1016/j.csbj.2022.08.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/04/2022] [Accepted: 08/04/2022] [Indexed: 11/05/2022] Open
Abstract
Temperature is an environmental condition that has a pervasive effect on cells along with all the molecules and reactions in them. The mechanisms by which prototypical RNA molecules sense and withstand heat have been identified mostly in bacteria and archaea. The relevance of these phenomena is, however, broader, and similar mechanisms have been recently found throughout the tree of life, from sex determination in reptiles to adaptation of viral RNA polymerases, to genetic disorders in humans. We illustrate the temperature dependence of RNA metabolism with examples from the synthesis to the degradation of mRNAs, and review recently emerged questions. Are cells exposed to greater temperature variations and gradients than previously surmised? How do cells reconcile the conflicting thermal stability requirements of primary and tertiary structures of RNAs? To what extent do enzymes contribute to the temperature compensation of the reaction rates in mRNA turnover by lowering the energy barrier of the catalyzed reactions? We conclude with the ecological, forensic applications of the temperature-dependence of RNA degradation and the biotechnological aspects of mRNA vaccine production.
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6
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Iakovlev M, Faravelli S, Becskei A. Gene Families With Stochastic Exclusive Gene Choice Underlie Cell Adhesion in Mammalian Cells. Front Cell Dev Biol 2021; 9:642212. [PMID: 33996799 PMCID: PMC8117012 DOI: 10.3389/fcell.2021.642212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/30/2021] [Indexed: 12/11/2022] Open
Abstract
Exclusive stochastic gene choice combines precision with diversity. This regulation enables most T-cells to express exactly one T-cell receptor isoform chosen from a large repertoire, and to react precisely against diverse antigens. Some cells express two receptor isoforms, revealing the stochastic nature of this process. A similar regulation of odorant receptors and protocadherins enable cells to recognize odors and confer individuality to cells in neuronal interaction networks, respectively. We explored whether genes in other families are expressed exclusively by analyzing single-cell RNA-seq data with a simple metric. This metric can detect exclusivity independently of the mean value and the monoallelic nature of gene expression. Chromosomal segments and gene families are more likely to express genes concurrently than exclusively, possibly due to the evolutionary and biophysical aspects of shared regulation. Nonetheless, gene families with exclusive gene choice were detected in multiple cell types, most of them are membrane proteins involved in ion transport and cell adhesion, suggesting the coordination of these two functions. Thus, stochastic exclusive expression extends beyond the prototypical families, permitting precision in gene choice to be combined with the diversity of intercellular interactions.
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7
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Lehman BJ, Lopez-Diaz FJ, Santisakultarm TP, Fang L, Shokhirev MN, Diffenderfer KE, Manor U, Emerson BM. Dynamic regulation of CTCF stability and sub-nuclear localization in response to stress. PLoS Genet 2021; 17:e1009277. [PMID: 33411704 PMCID: PMC7790283 DOI: 10.1371/journal.pgen.1009277] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 11/13/2020] [Indexed: 02/06/2023] Open
Abstract
The nuclear protein CCCTC-binding factor (CTCF) has diverse roles in chromatin architecture and gene regulation. Functionally, CTCF associates with thousands of genomic sites and interacts with proteins, such as cohesin, or non-coding RNAs to facilitate specific transcriptional programming. In this study, we examined CTCF during the cellular stress response in human primary cells using immune-blotting, quantitative real time-PCR, chromatin immunoprecipitation-sequence (ChIP-seq) analysis, mass spectrometry, RNA immunoprecipitation-sequence analysis (RIP-seq), and Airyscan confocal microscopy. Unexpectedly, we found that CTCF is exquisitely sensitive to diverse forms of stress in normal patient-derived human mammary epithelial cells (HMECs). In HMECs, a subset of CTCF protein forms complexes that localize to Serine/arginine-rich splicing factor (SC-35)-containing nuclear speckles. Upon stress, this species of CTCF protein is rapidly downregulated by changes in protein stability, resulting in loss of CTCF from SC-35 nuclear speckles and changes in CTCF-RNA interactions. Our ChIP-seq analysis indicated that CTCF binding to genomic DNA is largely unchanged. Restoration of the stress-sensitive pool of CTCF protein abundance and re-localization to nuclear speckles can be achieved by inhibition of proteasome-mediated degradation. Surprisingly, we observed the same characteristics of the stress response during neuronal differentiation of human pluripotent stem cells (hPSCs). CTCF forms stress-sensitive complexes that localize to SC-35 nuclear speckles during a specific stage of neuronal commitment/development but not in differentiated neurons. We speculate that these particular CTCF complexes serve a role in RNA processing that may be intimately linked with specific genes in the vicinity of nuclear speckles, potentially to maintain cells in a certain differentiation state, that is dynamically regulated by environmental signals. The stress-regulated activity of CTCF is uncoupled in persistently stressed, epigenetically re-programmed "variant" HMECs and certain cancer cell lines. These results reveal new insights into CTCF function in cell differentiation and the stress-response with implications for oxidative damage-induced cancer initiation and neuro-degenerative diseases.
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Affiliation(s)
- Bettina J. Lehman
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Fernando J. Lopez-Diaz
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Thom P. Santisakultarm
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Linjing Fang
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Maxim N. Shokhirev
- Razavi Newman Integrative Genomics and Bioinformatics Core, Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Kenneth E. Diffenderfer
- Stem Cell Core, Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Uri Manor
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Beverly M. Emerson
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California, United States of America
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8
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Jia Z, Wu Q. Clustered Protocadherins Emerge as Novel Susceptibility Loci for Mental Disorders. Front Neurosci 2020; 14:587819. [PMID: 33262685 PMCID: PMC7688460 DOI: 10.3389/fnins.2020.587819] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/26/2020] [Indexed: 12/24/2022] Open
Abstract
The clustered protocadherins (cPcdhs) are a subfamily of type I single-pass transmembrane cell adhesion molecules predominantly expressed in the brain. Their stochastic and combinatorial expression patterns encode highly diverse neural identity codes which are central for neuronal self-avoidance and non-self discrimination in brain circuit formation. In this review, we first briefly outline mechanisms for generating a tremendous diversity of cPcdh cell-surface assemblies. We then summarize the biological functions of cPcdhs in a wide variety of neurodevelopmental processes, such as neuronal migration and survival, dendritic arborization and self-avoidance, axonal tiling and even spacing, and synaptogenesis. We focus on genetic, epigenetic, and 3D genomic dysregulations of cPcdhs that are associated with various neuropsychiatric and neurodevelopmental diseases. A deeper understanding of regulatory mechanisms and physiological functions of cPcdhs should provide significant insights into the pathogenesis of mental disorders and facilitate development of novel diagnostic and therapeutic strategies.
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Affiliation(s)
| | - Qiang Wu
- Center for Comparative Biomedicine, MOE Key Laboratory of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, School of Life Sciences and Biotechnology, Institute of Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
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9
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Misteli T. The Self-Organizing Genome: Principles of Genome Architecture and Function. Cell 2020; 183:28-45. [PMID: 32976797 PMCID: PMC7541718 DOI: 10.1016/j.cell.2020.09.014] [Citation(s) in RCA: 311] [Impact Index Per Article: 77.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 08/03/2020] [Accepted: 09/02/2020] [Indexed: 01/17/2023]
Abstract
Genomes have complex three-dimensional architectures. The recent convergence of genetic, biochemical, biophysical, and cell biological methods has uncovered several fundamental principles of genome organization. They highlight that genome function is a major driver of genome architecture and that structural features of chromatin act as modulators, rather than binary determinants, of genome activity. The interplay of these principles in the context of self-organization can account for the emergence of structural chromatin features, the diversity and single-cell heterogeneity of nuclear architecture in cell types and tissues, and explains evolutionarily conserved functional features of genomes, including plasticity and robustness.
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Affiliation(s)
- Tom Misteli
- National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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10
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Wu Q, Jia Z. Wiring the Brain by Clustered Protocadherin Neural Codes. Neurosci Bull 2020; 37:117-131. [PMID: 32939695 PMCID: PMC7811963 DOI: 10.1007/s12264-020-00578-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/02/2020] [Indexed: 12/18/2022] Open
Abstract
There are more than a thousand trillion specific synaptic connections in the human brain and over a million new specific connections are formed every second during the early years of life. The assembly of these staggeringly complex neuronal circuits requires specific cell-surface molecular tags to endow each neuron with a unique identity code to discriminate self from non-self. The clustered protocadherin (Pcdh) genes, which encode a tremendous diversity of cell-surface assemblies, are candidates for neuronal identity tags. We describe the adaptive evolution, genomic structure, and regulation of expression of the clustered Pcdhs. We specifically focus on the emerging 3-D architectural and biophysical mechanisms that generate an enormous number of diverse cell-surface Pcdhs as neural codes in the brain.
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Affiliation(s)
- Qiang Wu
- Center for Comparative Biomedicine, Ministry of Education Key Lab of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, Joint International Research Laboratory of Metabolic and Developmental Sciences, Institute of Systems Biomedicine, Xinhua Hospital, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Zhilian Jia
- Center for Comparative Biomedicine, Ministry of Education Key Lab of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, Joint International Research Laboratory of Metabolic and Developmental Sciences, Institute of Systems Biomedicine, Xinhua Hospital, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
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11
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Wu Q, Liu P, Wang L. Many facades of CTCF unified by its coding for three-dimensional genome architecture. J Genet Genomics 2020; 47:407-424. [PMID: 33187878 DOI: 10.1016/j.jgg.2020.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/15/2020] [Accepted: 06/01/2020] [Indexed: 02/06/2023]
Abstract
CCCTC-binding factor (CTCF) is a multifunctional zinc finger protein that is conserved in metazoan species. CTCF is consistently found to play an important role in many diverse biological processes. CTCF/cohesin-mediated active chromatin 'loop extrusion' architects three-dimensional (3D) genome folding. The 3D architectural role of CTCF underlies its multifarious functions, including developmental regulation of gene expression, protocadherin (Pcdh) promoter choice in the nervous system, immunoglobulin (Ig) and T-cell receptor (Tcr) V(D)J recombination in the immune system, homeobox (Hox) gene control during limb development, as well as many other aspects of biology. Here, we review the pleiotropic functions of CTCF from the perspective of its essential role in 3D genome architecture and topological promoter/enhancer selection. We envision the 3D genome as an enormous complex architecture, with tens of thousands of CTCF sites as connecting nodes and CTCF proteins as mysterious bonds that glue together genomic building parts with distinct articulation joints. In particular, we focus on the internal mechanisms by which CTCF controls higher order chromatin structures that manifest its many façades of physiological and pathological functions. We also discuss the dichotomic role of CTCF sites as intriguing 3D genome nodes for seemingly contradictory 'looping bridges' and 'topological insulators' to frame a beautiful magnificent house for a cell's nuclear home.
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Affiliation(s)
- Qiang Wu
- MOE Key Lab of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, Center for Comparative Biomedicine, Institute of Systems Biomedicine, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University (SJTU), Shanghai, 200240, China.
| | - Peifeng Liu
- MOE Key Lab of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, Center for Comparative Biomedicine, Institute of Systems Biomedicine, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University (SJTU), Shanghai, 200240, China
| | - Leyang Wang
- MOE Key Lab of Systems Biomedicine, State Key Laboratory of Oncogenes and Related Genes, Center for Comparative Biomedicine, Institute of Systems Biomedicine, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University (SJTU), Shanghai, 200240, China
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12
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Lei J. A general mathematical framework for understanding the behavior of heterogeneous stem cell regeneration. J Theor Biol 2020; 492:110196. [PMID: 32067937 DOI: 10.1016/j.jtbi.2020.110196] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 12/28/2019] [Accepted: 02/11/2020] [Indexed: 11/21/2022]
Abstract
Stem cell heterogeneity is essential for homeostasis in tissue development. This paper establishes a general mathematical framework to model the dynamics of stem cell regeneration with cell heterogeneity and random transitions of epigenetic states. The framework generalizes the classical G0 cell cycle model and incorporates the epigenetic states of individual cells represented by a continuous multidimensional variable. In the model, the kinetic rates of cell behaviors, including proliferation, differentiation, and apoptosis, are dependent on their epigenetic states, and the random transitions of epigenetic states between cell cycles are represented by an inheritance probability function that describes the conditional probability of cell state changes. Moreover, the model can be extended to include genotypic changes and describe the process of gene mutation-induced tumor development. The proposed mathematical framework provides a generalized formula that helps us to understand various dynamic processes of stem cell regeneration, including tissue development, degeneration, and abnormal growth.
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Affiliation(s)
- Jinzhi Lei
- Zhou Pei-Yuan Center for Applied Mathematics, MOE Key Laboratory of Bioinformatics, Tsinghua University, Beijing 100084, China.
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13
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Becskei A. Tuning up Transcription Factors for Therapy. Molecules 2020; 25:E1902. [PMID: 32326099 PMCID: PMC7221782 DOI: 10.3390/molecules25081902] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/19/2022] Open
Abstract
The recent developments in the delivery and design of transcription factors put their therapeutic applications within reach, exemplified by cell replacement, cancer differentiation and T-cell based cancer therapies. The success of such applications depends on the efficacy and precision in the action of transcription factors. The biophysical and genetic characterization of the paradigmatic prokaryotic repressors, LacI and TetR and the designer transcription factors, transcription activator-like effector (TALE) and CRISPR-dCas9 revealed common principles behind their efficacy, which can aid the optimization of transcriptional activators and repressors. Further studies will be required to analyze the linkage between dissociation constants and enzymatic activity, the role of phase separation and squelching in activation and repression and the long-range interaction of transcription factors with epigenetic regulators in the context of the chromosomes. Understanding these mechanisms will help to tailor natural and synthetic transcription factors to the needs of specific applications.
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Affiliation(s)
- Attila Becskei
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
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14
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Three-dimensional genome architectural CCCTC-binding factor makes choice in duplicated enhancers at Pcdhα locus. SCIENCE CHINA-LIFE SCIENCES 2020; 63:835-844. [PMID: 32249388 DOI: 10.1007/s11427-019-1598-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 12/04/2019] [Indexed: 01/04/2023]
Abstract
During development, gene expression is spatiotemporally regulated by long-distance chromatin interactions between distal enhancers and target promoters. However, how specificity of the interactions between enhancers and promoters is achieved remains largely unknown. As there are far more enhancers than promoters in mammalian genomes, the complexities of enhancer choice during gene regulation remain obscure. CTCF, the CCCTC-binding factor that directionally binds to a vast range of genomic sites known as CBSs (CTCF-binding sites), mediates oriented chromatin looping between a substantial set of distal enhancers and target promoters. To investigate mechanisms by which CTCF engages in enhancer choice, we used CRISPR/Cas9-based DNA-fragment editing to duplicate CBS-containing enhancers and promoters in the native genomic locus of the clustered Pcdhα genes. We found that the promoter is regulated by the proximal one among duplicated enhancers and that this choice is dependent on CTCF-mediated directional enhancer-promoter looping. In addition, gene expression is unaltered upon the switch of enhancers. Moreover, after promoter duplication, only the proximal promoter is chosen by CTCF-mediated directional chromatin looping to contact with the distal enhancer. Finally, we demonstrated that both enhancer activation and chromatin looping with the promoter are essential for gene expression. These findings have important implications regarding the role of CTCF in specific interactions between enhancers and promoters as well as developmental regulation of gene expression by enhancer switching.
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15
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Chromatin establishes an immature version of neuronal protocadherin selection during the naive-to-primed conversion of pluripotent stem cells. Nat Genet 2019; 51:1691-1701. [PMID: 31740836 PMCID: PMC7061033 DOI: 10.1038/s41588-019-0526-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 09/30/2019] [Indexed: 01/09/2023]
Abstract
In the mammalian genome, the clustered protocadherin (cPcdh) locus is a paradigm of stochastic gene expression with the potential to generate a unique cPcdh combination in every neuron. Here, we report a chromatin-based mechanism emerging during the transition from the naive to the primed states of cell pluripotency that reduces by orders of magnitude the combinatorial potential in the human cPcdh locus. This mechanism selectively increases the frequency of stochastic selection of a small subset of cPcdh genes after neuronal differentiation in monolayers, months-old organoids, and engrafted cells in the rat spinal cord. Signs of these frequent selections can be observed in the brain throughout fetal development and disappear after birth, unless there is a condition of delayed maturation such as Down Syndrome. We therefore propose that a pattern of limited cPcdh diversity is maintained while human neurons still retain fetal-like levels of maturation. Short and long-term cultures of human stem cell-derived neurons reveal that a pattern of restricted selection of clustered protocadherin isoforms, pre-established in pluripotent cells, distinguishes immature from mature neurons.
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16
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Sun M, Zhang J. Chromosome-wide co-fluctuation of stochastic gene expression in mammalian cells. PLoS Genet 2019; 15:e1008389. [PMID: 31525198 PMCID: PMC6762216 DOI: 10.1371/journal.pgen.1008389] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 09/26/2019] [Accepted: 08/28/2019] [Indexed: 12/31/2022] Open
Abstract
Gene expression is subject to stochastic noise, but to what extent and by which means such stochastic variations are coordinated among different genes are unclear. We hypothesize that neighboring genes on the same chromosome co-fluctuate in expression because of their common chromatin dynamics, and verify it at the genomic scale using allele-specific single-cell RNA-sequencing data of mouse cells. Unexpectedly, the co-fluctuation extends to genes that are over 60 million bases apart. We provide evidence that this long-range effect arises in part from chromatin co-accessibilities of linked loci attributable to three-dimensional proximity, which is much closer intra-chromosomally than inter-chromosomally. We further show that genes encoding components of the same protein complex tend to be chromosomally linked, likely resulting from natural selection for intracellular among-component dosage balance. These findings have implications for both the evolution of genome organization and optimal design of synthetic genomes in the face of gene expression noise.
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Affiliation(s)
- Mengyi Sun
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
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17
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Wada T, Wallerich S, Becskei A. Synthetic Transcription Factors Switch from Local to Long-Range Control during Cell Differentiation. ACS Synth Biol 2019; 8:223-231. [PMID: 30624895 DOI: 10.1021/acssynbio.8b00369] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Genes, including promoters and enhancers, are regulated by short- and long-range interactions in higher eukaryotes. It is unclear how mammalian gene expression subject to such a combinatorial regulation can be controlled by synthetic transcription factors (TF). Here, we studied how synthetic TALE transcriptional activators and repressors affect the expression of genes in a gene array during cellular differentiation. The protocadherin gene array is silent in mouse embryonic stem (ES) and neuronal progenitor cells. The TALE transcriptional activator recruited to a promoter activates specifically the target gene in ES cells. Upon differentiation into neuronal progenitors, the transcriptional regulatory logic changes: the same activator behaves like an enhancer, activating distant genes in a correlated, stochastic fashion. The long-range effect is reflected by the alterations in CpG methylation. Our findings reveal the limits of precision and the opportunities in the control of gene expression for TF-based therapies in cells of various differentiation stages.
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Affiliation(s)
- Takeo Wada
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Sandrine Wallerich
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Attila Becskei
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
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