scholarly journals Chromosome disentanglement driven via optimal compaction of loop-extruded brush structures

2019 ◽  
Author(s):  
Sumitabha Brahmachari ◽  
John F. Marko
Keyword(s):  
Expression Patterns ◽  
Polymer Brush ◽  
Chromosome Size ◽  
Mitotic Chromosomes ◽  
Mechanical Stiffness ◽  
Structural Reorganization ◽  
Metaphase Chromosomes ◽  
Topo Ii ◽  
Strand Passage

AbstractEukaryote cell division features a chromosome compaction-decompaction cycle that is synchronized with their physical and topological segregation. It has been proposed that lengthwise compaction of chromatin into mitotic chromosomes via loop extrusion underlies the compaction-segregation/resolution process. We analyze this disentanglement scheme via considering the chromosome to be a succession of DNA/chromatin loops - a polymer “brush” - where active extrusion of loops controls the brush structure. Given topoisomerase (TopoII)-catalyzed topology fluctuations, we find that inter-chromosome entanglements are minimized for a certain “optimal” loop that scales with the chromosome size. The optimal loop organization is in accord with experimental data across species, suggesting an important structural role of genomic loops in maintaining a less entangled genome. Application of the model to the interphase genome indicates that active loop extrusion can maintain a level of chromosome compaction with suppressed entanglements; the transition to the metaphase state requires higher lengthwise compaction, and drives complete topological segregation. Optimized genomic loops may provide a means for evolutionary propagation of gene-expression patterns while simultaneously maintaining a disentangled genome. We also find that compact metaphase chromosomes have a densely packed core along their cylindrical axes that explains their observed mechanical stiffness. Our model connects chromosome structural reorganization to topological resolution through the cell cycle, and highlights a mechanism of directing Topo-II mediated strand passage via loop extrusion driven lengthwise compaction.

scholarly journals Chromosome disentanglement driven via optimal compaction of loop-extruded brush structures

2019 ◽  
Vol 116 (50) ◽  
pp. 24956-24965 ◽  
Author(s):  
Sumitabha Brahmachari ◽  
John F. Marko
Keyword(s):  
Expression Patterns ◽  
Polymer Brush ◽  
Mitotic Chromosomes ◽  
Mechanical Stiffness ◽  
Structural Reorganization ◽  
Metaphase Chromosomes ◽  
Dna Topoisomerase ◽  
Topo Ii ◽  
Strand Passage

Eukaryote cell division features a chromosome compaction–decompaction cycle that is synchronized with their physical and topological segregation. It has been proposed that lengthwise compaction of chromatin into mitotic chromosomes via loop extrusion underlies the compaction-segregation/resolution process. We analyze this disentanglement scheme via considering the chromosome to be a succession of DNA/chromatin loops—a polymer “brush”—where active extrusion of loops controls the brush structure. Given type-II DNA topoisomerase (Topo II)-catalyzed topology fluctuations, we find that interchromosome entanglements are minimized for a certain “optimal” loop that scales with the chromosome size. The optimal loop organization is in accord with experimental data across species, suggesting an important structural role of genomic loops in maintaining a less entangled genome. Application of the model to the interphase genome indicates that active loop extrusion can maintain a level of chromosome compaction with suppressed entanglements; the transition to the metaphase state requires higher lengthwise compaction and drives complete topological segregation. Optimized genomic loops may provide a means for evolutionary propagation of gene-expression patterns while simultaneously maintaining a disentangled genome. We also find that compact metaphase chromosomes have a densely packed core along their cylindrical axes that explains their observed mechanical stiffness. Our model connects chromosome structural reorganization to topological resolution through the cell cycle and highlights a mechanism of directing Topo II-mediated strand passage via loop extrusion-driven lengthwise compaction.

Banding in mitotic chromosomes of Brassica campestris var. pekinensis with a trypsin–Giemsa method

Genome ◽  
1992 ◽  
Vol 35 (5) ◽  
pp. 899-901 ◽  
Author(s):  
Soryu Nishibayasahi
Keyword(s):  
Banding Pattern ◽  
Brassica Campestris ◽  
Chromosome Size ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Secondary Constrictions

In Brassica campestris var. pekinensis cv. CR-strong, the karyotype comprised 12 median, 6 submedian, and 2 sub-terminal chromosomes. Secondary constrictions were observed in the two subterminal chromosomes. Banding pattern appeared very clearly in metaphase chromosomes with a trypsin–Giemsa method. It was possible to classify the chromosomes into 10 types (C1–C10), based on the chromosome size, shape, and banding pattern.Key words: Brassica campestris var. pekinensis, mitotic chromosomes, G-banding.

scholarly journals CENP-A and topoisomerase-II antagonistically affect chromosome length

2017 ◽  
Vol 216 (9) ◽  
pp. 2645-2655 ◽  
Author(s):  
A.-M. Ladouceur ◽  
Rajesh Ranjan ◽  
Lydia Smith ◽  
Tanner Fadero ◽  
Jennifer Heppert ◽  
...  
Keyword(s):  
Self Assembly ◽  
Topoisomerase Ii ◽  
Chromosome Length ◽  
Chromosome Size ◽  
Mitotic Chromosomes ◽  
Nuclear Trafficking ◽  
C Elegans ◽  
Protein Levels ◽  
Histone H3 Variant ◽  
Topo Ii

The size of mitotic chromosomes is coordinated with cell size in a manner dependent on nuclear trafficking. In this study, we conducted an RNA interference screen of the Caenorhabditis elegans nucleome in a strain carrying an exceptionally long chromosome and identified the centromere-specific histone H3 variant CENP-A and the DNA decatenizing enzyme topoisomerase-II (topo-II) as candidate modulators of chromosome size. In the holocentric organism C. elegans, CENP-A is positioned periodically along the entire length of chromosomes, and in mitosis, these genomic regions come together linearly to form the base of kinetochores. We show that CENP-A protein levels decreased through development coinciding with chromosome-size scaling. Partial loss of CENP-A protein resulted in shorter mitotic chromosomes, consistent with a role in setting chromosome length. Conversely, topo-II levels were unchanged through early development, and partial topo-II depletion led to longer chromosomes. Topo-II localized to the perimeter of mitotic chromosomes, excluded from the centromere regions, and depletion of topo-II did not change CENP-A levels. We propose that self-assembly of centromeric chromatin into an extended linear array promotes elongation of the chromosome, whereas topo-II promotes chromosome-length shortening.

scholarly journals Condensin controls mitotic chromosome stiffness and stability without forming a structurally contiguous scaffold

2018 ◽  
Author(s):  
Mingxuan Sun ◽  
Ronald Biggs ◽  
Jessica Hornick ◽  
John F. Marko
Keyword(s):  
Large Scale ◽  
Force Measurement ◽  
Protein Complexes ◽  
Elastic Stiffness ◽  
Main Element ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Fold Reduction ◽  
Subunit Expression

AbstractDuring cell division, chromosomes must be folded into their compact mitotic form to ensure their segregation. This process is thought to be largely controlled by the action of condensin SMC protein complexes on chromatin fibers. However, how condensins organize metaphase chromosomes is not understood. We have combined micromanipulation of single human mitotic chromosomes, sub-nanonewton force measurement, siRNA interference of condensin subunit expression, and fluorescence microscopy, to analyze the role of condensin in large-scale chromosome organization. Condensin depletion leads to a dramatic (~10 fold) reduction in chromosome elastic stiffness relative to the native, non-depleted case. We also find that prolonged metaphase stalling of cells leads to overloading of chromosomes with condensin, with abnormally high chromosome stiffness. These results demonstrate that condensin is a main element controlling the stiffness of mitotic chromosomes. Isolated, slightly stretched chromosomes display a discontinuous condensing staining pattern, suggesting that condensins organize mitotic chromosomes by forming isolated compaction centers that do not form a continuous scaffold.

Dysregulation of HOX as a Potential Therapeutic Target in Breast Cancer

2020 ◽  
Vol 27 ◽  
Author(s):  
Ji-Yeon Lee ◽  
Myoung Hee Kim
Keyword(s):  
Breast Cancer ◽  
Hox Genes ◽  
Therapeutic Potential ◽  
Expression Patterns ◽  
Genome Structure ◽  
Control Cell ◽  
Three Dimensional ◽  
Cellular Processes ◽  
Hox Protein

: HOX genes belong to the highly conserved homeobox superfamily, responsible for the regulation of various cellular processes that control cell homeostasis, from embryogenesis to carcinogenesis. The abnormal expression of HOX genes is observed in various cancers, including breast cancer; they act as oncogenes or as suppressors of cancer, according to context. In this review, we analyze HOX gene expression patterns in breast cancer and examine their relationship, based on the three-dimensional genome structure of the HOX locus. The presence of non-coding RNAs, embedded within the HOX cluster, and the role of these molecules in breast cancer have been reviewed. We further evaluate the characteristic activity of HOX protein in breast cancer and its therapeutic potential.

scholarly journals The potential regulatory role of hsa_circ_0004104 in the persistency of atrial fibrillation by promoting cardiac fibrosis via TGF-β pathway

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yuanfeng Gao ◽  
Ye Liu ◽  
Yuan Fu ◽  
Qianhui Wang ◽  
Zheng Liu ◽  
...  
Keyword(s):  
Cardiac Fibrosis ◽  
Expression Patterns ◽  
In Silico Analysis ◽  
Significant Negative Correlation ◽  
Circular Rnas ◽  
Tgf Beta ◽  
Rt Pcr ◽  
Derivation Cohort ◽  
Tgf Β1

Abstract Introduction The progression of paroxysmal AF (PAF) to persistent AF (PsAF) worsens the prognosis of AF, but its underlying mechanisms remain elusive. Recently, circular RNAs (circRNAs) were reported to be associated with cardiac fibrosis. In case of the vital role of cardiac fibrosis in AF persistency, we hypothesis that circRNAs may be potential regulators in the process of AF progression. Materials and methods 6 persistent and 6 paroxysmal AF patients were enrolled as derivation cohort. Plasma circRNAs expressions were determined by microarray and validated by RT-PCR. Fibrosis level, manifested by serum TGF-β, was determined by ELISA. Pathways and related non-coding RNAs involving in the progression of AF regulated were predicted by in silico analysis. Results PsAF patients showed a distinct circRNAs expression profile with 92 circRNAs significantly dysregulated (fold change ≥ 2, p < 0.05), compared with PAF patients. The validity of the expression patterns was subsequently validated by RT-PCR in another 60 AF patients (30 PsAF and PAF, respectively). In addition, all the 5 up and down regulated circRNAs were clustered in MAPK and TGF-beta signaling pathway by KEGG pathway analysis. Among the 5 circRNAs, hsa_circ_0004104 was consistently downregulated in PsAF group (0.6 ± 0.33 vs 1.46 ± 0.41, p < 0.001) and predicted to target several AF and/or cardiac fibrosis related miRNAs reported by previous studies. In addition, TGF-β1 level was significantly higher in the PsAF group (5560.23 ± 1833.64 vs 2236.66 ± 914.89, p < 0.001), and hsa_circ_0004104 showed a significant negative correlation with TGF-β1 level (r = − 0.797, p < 0.001). Conclusion CircRNAs dysregulation plays vital roles in AF persistency. hsa_circ_0004104 could be a potential regulator and biomarker in AF persistency by promoting cardiac fibrosis via targeting MAPK and TGF-beta pathways.

scholarly journals Longitudinal Expression of Testicular TAS1R3 from Prepuberty to Sexual Maturity in Congjiang Xiang Pigs

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 437
Author(s):  
Ting Gong ◽  
Weiyong Wang ◽  
Houqiang Xu ◽  
Yi Yang ◽  
Xiang Chen ◽  
...  
Keyword(s):  
Sexual Maturity ◽  
Cell Function ◽  
Expression Patterns ◽  
Taste Receptor ◽  
Receptor Type ◽  
Mrna Levels ◽  
Early Puberty ◽  
Specific Expression

Testicular expression of taste receptor type 1 subunit 3 (T1R3), a sweet/umami taste receptor, has been implicated in spermatogenesis and steroidogenesis in mice. We explored the role of testicular T1R3 in porcine postnatal development using the Congjiang Xiang pig, a rare Chinese miniature pig breed. Based on testicular weights, morphology, and testosterone levels, four key developmental stages were identified in the pig at postnatal days 15–180 (prepuberty: 30 day; early puberty: 60 day; late puberty: 90 day; sexual maturity: 120 day). During development, testicular T1R3 exhibited stage-dependent and cell-specific expression patterns. In particular, T1R3 levels increased significantly from prepuberty to puberty (p < 0.05), and expression remained high until sexual maturity (p < 0.05), similar to results for phospholipase Cβ2 (PLCβ2). The strong expressions of T1R3/PLCβ2 were observed at the cytoplasm of elongating/elongated spermatids and Leydig cells. In the eight-stage cycle of the seminiferous epithelium in pigs, T1R3/PLCβ2 levels were higher in the spermatogenic epithelium at stages II–VI than at the other stages, and the strong expressions were detected in elongating/elongated spermatids and residual bodies. The message RNA (mRNA) levels of taste receptor type 1 subunit 1 (T1R1) in the testis showed a similar trend to levels of T1R3. These data indicate a possible role of T1R3 in the regulation of spermatid differentiation and Leydig cell function.

scholarly journals Role of miRNAs in Normal Endometrium and in Endometrial Disorders: Comprehensive Review

2021 ◽  
Vol 10 (16) ◽  
pp. 3457
Author(s):  
Kamila Kolanska ◽  
Sofiane Bendifallah ◽  
Geoffroy Canlorbe ◽  
Arsène Mekinian ◽  
Cyril Touboul ◽  
...  
Keyword(s):  
Endometrial Cancer ◽  
Mirna Expression ◽  
Expression Patterns ◽  
Mirna Regulation ◽  
Rigorous Analysis ◽  
Sexual Hormones ◽  
Physiological Mechanisms ◽  
Normal Endometrium ◽  
Gynecological Disorders

The molecular responses to hormonal stimuli in the endometrium are modulated at the transcriptional and post-transcriptional stages. Any imbalance in cellular and molecular endometrial homeostasis may lead to gynecological disorders. MicroRNAs (miRNAs) are involved in a wide variety of physiological mechanisms and their expression patterns in the endometrium are currently attracting a lot of interest. miRNA regulation could be hormone dependent. Conversely, miRNAs could regulate the action of sexual hormones. Modifications to miRNA expression in pathological situations could either be a cause or a result of the existing pathology. The complexity of miRNA actions and the diversity of signaling pathways controlled by numerous miRNAs require rigorous analysis and findings need to be interpreted with caution. Alteration of miRNA expression in women with endometriosis has been reported. Thus, a potential diagnostic test supported by a specific miRNA signature could contribute to early diagnosis and a change in the therapeutic paradigm. Similarly, specific miRNA profile signatures are expected for RIF and endometrial cancer, with direct implications for associated therapies for RIF and adjuvant therapies for endometrial cancer. Advances in targeted therapies based on the regulation of miRNA expression are under evaluation.

scholarly journals Genome-wide identification of the GATA transcription factor family and their expression patterns under temperature and salt stress in Aspergillus oryzae

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chunmiao Jiang ◽  
Gongbo Lv ◽  
Jinxin Ge ◽  
Bin He ◽  
Zhe Zhang ◽  
...  
Keyword(s):  
Salt Stress ◽  
Expression Patterns ◽  
Interaction Network ◽  
Protein Protein Interaction ◽  
Genome Wide ◽  
Gata Transcription Factor ◽  
Starting Point ◽  
Evolutionary Features ◽  
First Time

AbstractGATA transcription factors (TFs) are involved in the regulation of growth processes and various environmental stresses. Although GATA TFs involved in abiotic stress in plants and some fungi have been analyzed, information regarding GATA TFs in Aspergillusoryzae is extremely poor. In this study, we identified and functionally characterized seven GATA proteins from A.oryzae 3.042 genome, including a novel AoSnf5 GATA TF with 20-residue between the Cys-X2-Cys motifs which was found in Aspergillus GATA TFs for the first time. Phylogenetic analysis indicated that these seven A. oryzae GATA TFs could be classified into six subgroups. Analysis of conserved motifs demonstrated that Aspergillus GATA TFs with similar motif compositions clustered in one subgroup, suggesting that they might possess similar genetic functions, further confirming the accuracy of the phylogenetic relationship. Furthermore, the expression patterns of seven A.oryzae GATA TFs under temperature and salt stresses indicated that A. oryzae GATA TFs were mainly responsive to high temperature and high salt stress. The protein–protein interaction network of A.oryzae GATA TFs revealed certain potentially interacting proteins. The comprehensive analysis of A. oryzae GATA TFs will be beneficial for understanding their biological function and evolutionary features and provide an important starting point to further understand the role of GATA TFs in the regulation of distinct environmental conditions in A.oryzae.

scholarly journals Genome-Wide Expression Patterns of Rhoptry Kinases during the Eimeria tenella Life-Cycle

2021 ◽  
Vol 9 (8) ◽  
pp. 1621
Author(s):  
Adeline Ribeiro E Silva ◽  
Alix Sausset ◽  
Françoise I. Bussière ◽  
Fabrice Laurent ◽  
Sonia Lacroix-Lamandé ◽  
...  
Keyword(s):  
Life Cycle ◽  
Expression Patterns ◽  
Housekeeping Genes ◽  
Catalytic Triad ◽  
Eimeria Tenella ◽  
Apicomplexan Parasites ◽  
Genome Wide ◽  
Infected Cells ◽  
First And Second Generation

Kinome from apicomplexan parasites is composed of eukaryotic protein kinases and Apicomplexa specific kinases, such as rhoptry kinases (ROPK). Ropk is a gene family that is known to play important roles in host–pathogen interaction in Toxoplasma gondii but is still poorly described in Eimeria tenella, the parasite responsible for avian coccidiosis worldwide. In the E. tenella genome, 28 ropk genes are predicted and could be classified as active (n = 7), inactive (incomplete catalytic triad, n = 12), and non-canonical kinases (active kinase with a modified catalytic triad, n = 9). We characterized the ropk gene expression patterns by real-time quantitative RT-PCR, normalized by parasite housekeeping genes, during the E. tenella life-cycle. Analyzed stages were: non-sporulated oocysts, sporulated oocysts, extracellular and intracellular sporozoites, immature and mature schizonts I, first- and second-generation merozoites, and gametes. Transcription of all those predicted ropk was confirmed. The mean intensity of transcription was higher in extracellular stages and 7–9 ropk were specifically transcribed in merozoites in comparison with sporozoites. Transcriptional profiles of intracellular stages were closely related to each other, suggesting a probable common role of ROPKs in hijacking signaling pathways and immune responses in infected cells. These results provide a solid basis for future functional analysis of ROPK from E. tenella.

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