scholarly journals Influence of Nanotopography on Early Bone Healing during Controlled Implant Loading

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2191
Author(s):  
Renan de Barros e Lima Bueno ◽  
Katia Ponce ◽  
Ana Dias ◽  
Dainelys Guadarrama Bello ◽  
John Brunski ◽  
...  
Keyword(s):  
Bone Formation ◽  
Cell Fate ◽  
Bone Healing ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Implant Surface ◽  
Bone Implant ◽  
Cell Fate Decisions ◽  
High Bone ◽  
Implant Loading

Nanoscale surface modifications influence peri-implant cell fate decisions and implant loading generates local tissue deformation, both of which will invariably impact bone healing. The objective of this study is to determine how loading affects healing around implants with nanotopography. Implants with a nanoporous surface were placed in over-sized osteotomies in rat tibiae and held stable by a system that permits controlled loading. Three regimens were applied: (a) no loading, (b) one daily loading session with a force of 1.5N, and (c) two such daily sessions. At 7 days post implantation, animals were sacrificed for histomorphometric and DNA microarray analyses. Implants subjected to no loading or only one daily loading session achieved high bone-implant contact (BIC), bone-implant distance (BID) and bone formation area near the implant (BFAt) values, while those subjected to two daily loading sessions showed less BFAt and BIC and more BID. Gene expression profiles differed between all groups mainly in unidentified genes, and no modulation of genes associated with inflammatory pathways was detected. These results indicate that implants with nanotopography can achieve a high level of bone formation even under micromotion and limit the inflammatory response to the implant surface.

scholarly journals Quantifying the Stability of Coupled Genetic and Epigenetic Switches With Variational Methods

2021 ◽  
Vol 11 ◽  
Author(s):  
Amogh Sood ◽  
Bin Zhang
Keyword(s):  
Gene Regulation ◽  
Transcription Factors ◽  
Cell Fate ◽  
Histone Modifications ◽  
Regulatory Networks ◽  
Variational Principles ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Cell Fate Decisions ◽  
The Impact

The Waddington landscape provides an intuitive metaphor to view development as a ball rolling down the hill, with distinct phenotypes as basins and differentiation pathways as valleys. Since, at a molecular level, cell differentiation arises from interactions among the genes, a mathematical definition for the Waddington landscape can, in principle, be obtained by studying the gene regulatory networks. For eukaryotes, gene regulation is inextricably and intimately linked to histone modifications. However, the impact of such modifications on both landscape topography and stability of attractor states is not fully understood. In this work, we introduced a minimal kinetic model for gene regulation that combines the impact of both histone modifications and transcription factors. We further developed an approximation scheme based on variational principles to solve the corresponding master equation in a second quantized framework. By analyzing the steady-state solutions at various parameter regimes, we found that histone modification kinetics can significantly alter the behavior of a genetic network, resulting in qualitative changes in gene expression profiles. The emerging epigenetic landscape captures the delicate interplay between transcription factors and histone modifications in driving cell-fate decisions.

scholarly journals Long Non-Coding RNAs in the Control of Gametogenesis: Lessons from Fission Yeast

2021 ◽  
Vol 7 (2) ◽  
pp. 34
Author(s):  
Vedrana Andric ◽  
Mathieu Rougemaille
Keyword(s):  
Fission Yeast ◽  
Cell Fate ◽  
Genetic Information ◽  
Developmental Process ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Cell Fate Decisions ◽  
Genome Expression ◽  
Non Coding Rnas ◽  
Cycle Dependent

Long non-coding RNAs (lncRNAs) contribute to cell fate decisions by modulating genome expression and stability. In the fission yeast Schizosaccharomyces pombe, the transition from mitosis to meiosis results in a marked remodeling of gene expression profiles, which ultimately ensures gamete production and inheritance of genetic information to the offspring. This key developmental process involves a set of dedicated lncRNAs that shape cell cycle-dependent transcriptomes through a variety of mechanisms, including epigenetic modifications and the modulation of transcription, post-transcriptional and post-translational regulations, and that contribute to meiosis-specific chromosomal events. In this review, we summarize the biology of these lncRNAs, from their identification to mechanism of action, and discuss their regulatory role in the control of gametogenesis.

Abstract 15751: A New Role of Sox6 in Renin Regulation

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Jose Gomez ◽  
Eric Sum ◽  
Anna Keyte ◽  
Conrad Hodgkinson ◽  
Mary Hutson ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cell Fate ◽  
Kidney Development ◽  
Ex Vivo ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Renin Angiotensin System ◽  
Adult Kidney ◽  
Fold Reduction

Introduction: The renin-angiotensin system (RAS) is an important component of blood pressure regulation in mammals. Renin catalyzes the rate limiting step of RAS, is produced and stored by Juxtaglomerular (JG) cells in the kidney. However, the transcriptional mechanisms that govern the specification of renin expressing cells under normal or pathophysiological conditions remain poorly understood. During blood pressure changes the number of adult renal cells expressing renin increase through a process termed JG recruitment. We found that this process involves differentiation mesenchymal stromal-like cells (MSC) to renin expressing cells. Our aim in this study was to determine new regulators of renin cell fate during kidney development and JG recruitment. Methods: Gene expression profiles of MSC and JG cells were performed with Affymetrix Mouse 430 2.0 array. In vitro assays were performed in adult renal MSCs isolated from C57BL6 Ren1c YFP mice. Renin expression in vitro was induced by treatment with IBMX and Forskolin. MSC were transduced with lentivirus carrying vectors for Sox6, Sox6 shRNA or controls. Ex vivo analysis was performed in embryonic kidneys (14.5 dpc) isolated and transduced with Sox6 or scrambled shRNA, kidneys were then cultured for 4 days and the expression of Sox6 and Renin analyzed by IHC. Results: Data showed that the transcription factor Sox6 is expressed in renin producing cells in the developing kidney (n=4) and in the adult kidney after stimulation that promotes JG recruitment (n=3). Overexpression of Sox6 (n=3, P<0.05) enhanced differentiation of renal MSCs to renin producing cells in vitro , and Sox6 knockdown reduced differentiation of renal MSC to renin producing cells in vitro (6-fold, n=4, P<0.01). Furthermore, knockdown of Sox6 in an ex vivo model of kidney development resulted in a 5-fold reduction in renin expressing cells (n=4, P<0.05). Conclusion: These results support a novel role for Sox6 in the development of renin expressing cells. This may have implications for renal development and physiology, opening new possibilities of addressing questions regarding both developmental and physiological regulation of renin.

scholarly journals Distinct p53 acetylation cassettes differentially influence gene-expression patterns and cell fate

2006 ◽  
Vol 173 (4) ◽  
pp. 533-544 ◽  
Author(s):  
Chad D. Knights ◽  
Jason Catania ◽  
Simone Di Giovanni ◽  
Selen Muratoglu ◽  
Ricardo Perez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Protein Interactions ◽  
Posttranslational Modifications ◽  
Biological Activities ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Gene Expression Profiles ◽  
P53 Gene ◽  
Protein Protein Interactions

The activity of the p53 gene product is regulated by a plethora of posttranslational modifications. An open question is whether such posttranslational changes act redundantly or dependently upon one another. We show that a functional interference between specific acetylated and phosphorylated residues of p53 influences cell fate. Acetylation of lysine 320 (K320) prevents phosphorylation of crucial serines in the NH2-terminal region of p53; only allows activation of genes containing high-affinity p53 binding sites, such as p21/WAF; and promotes cell survival after DNA damage. In contrast, acetylation of K373 leads to hyperphosphorylation of p53 NH2-terminal residues and enhances the interaction with promoters for which p53 possesses low DNA binding affinity, such as those contained in proapoptotic genes, leading to cell death. Further, acetylation of each of these two lysine clusters differentially regulates the interaction of p53 with coactivators and corepressors and produces distinct gene-expression profiles. By analogy with the “histone code” hypothesis, we propose that the multiple biological activities of p53 are orchestrated and deciphered by different “p53 cassettes,” each containing combination patterns of posttranslational modifications and protein–protein interactions.

Pluripotent Stem Cells Induced from Mouse Somatic Cells by Small-Molecule Compounds

Science ◽  
2013 ◽  
Vol 341 (6146) ◽  
pp. 651-654 ◽  
Author(s):  
Pingping Hou ◽  
Yanqin Li ◽  
Xu Zhang ◽  
Chun Liu ◽  
Jingyang Guan ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Fate ◽  
Small Molecule ◽  
Pluripotent Stem Cells ◽  
Genetic Manipulation ◽  
Expression Profiles ◽  
Somatic Cells ◽  
Embryonic Stem ◽  
Gene Expression Profiles ◽  
Clinical Applications

Pluripotent stem cells can be induced from somatic cells, providing an unlimited cell resource, with potential for studying disease and use in regenerative medicine. However, genetic manipulation and technically challenging strategies such as nuclear transfer used in reprogramming limit their clinical applications. Here, we show that pluripotent stem cells can be generated from mouse somatic cells at a frequency up to 0.2% using a combination of seven small-molecule compounds. The chemically induced pluripotent stem cells resemble embryonic stem cells in terms of their gene expression profiles, epigenetic status, and potential for differentiation and germline transmission. By using small molecules, exogenous “master genes” are dispensable for cell fate reprogramming. This chemical reprogramming strategy has potential use in generating functional desirable cell types for clinical applications.

scholarly journals AMPKβ1 and AMPKβ2 define an isoform-specific gene signature in human pluripotent stem cells, differentially mediating cardiac lineage specification

2020 ◽  
Vol 295 (51) ◽  
pp. 17659-17671
Author(s):  
Nicole Ziegler ◽  
Erik Bader ◽  
Alexey Epanchintsev ◽  
Daniel Margerie ◽  
Aimo Kannt ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Cell Fate ◽  
Pluripotent Stem Cells ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Specific Gene ◽  
Wide Range ◽  
Specific Manner ◽  
Cardiac Lineage

AMP-activated protein kinase (AMPK) is a key regulator of energy metabolism that phosphorylates a wide range of proteins to maintain cellular homeostasis. AMPK consists of three subunits: α, β, and γ. AMPKα and β are encoded by two genes, the γ subunit by three genes, all of which are expressed in a tissue-specific manner. It is not fully understood, whether individual isoforms have different functions. Using RNA-Seq technology, we provide evidence that the loss of AMPKβ1 and AMPKβ2 lead to different gene expression profiles in human induced pluripotent stem cells (hiPSCs), indicating isoform-specific function. The knockout of AMPKβ2 was associated with a higher number of differentially regulated genes than the deletion of AMPKβ1, suggesting that AMPKβ2 has a more comprehensive impact on the transcriptome. Bioinformatics analysis identified cell differentiation as one biological function being specifically associated with AMPKβ2. Correspondingly, the two isoforms differentially affected lineage decision toward a cardiac cell fate. Although the lack of PRKAB1 impacted differentiation into cardiomyocytes only at late stages of cardiac maturation, the availability of PRKAB2 was indispensable for mesoderm specification as shown by gene expression analysis and histochemical staining for cardiac lineage markers such as cTnT, GATA4, and NKX2.5. Ultimately, the lack of AMPKβ1 impairs, whereas deficiency of AMPKβ2 abrogates differentiation into cardiomyocytes. Finally, we demonstrate that AMPK affects cellular physiology by engaging in the regulation of hiPSC transcription in an isoform-specific manner, providing the basis for further investigations elucidating the role of dedicated AMPK subunits in the modulation of gene expression.

Does surface anodisation of titanium implants change osseointegration and make their extraction from bone any easier?

2008 ◽  
Vol 21 (03) ◽  
pp. 202-210 ◽  
Author(s):  
J. Langhoff ◽  
J. Mayer ◽  
L. Faber ◽  
S. Kaestner ◽  
G. Guibert ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Titanium Implant ◽  
Titanium Implants ◽  
Implant Surface ◽  
Bone Implant ◽  
High Bone ◽  
Titanium Surfaces ◽  
Anodized Titanium ◽  
Titanium Implant Surface

Summary Objectives: Titanium implants have a tendency for high bone-implant bonding, and, in comparison to stainless steel implants are more difficult to remove. The current study was carried out to evaluate, i) the release strength of three selected anodized titanium surfaces with increased nanohardness and low roughness, and ii) bone-implant bonding in vivo. These modified surfaces were intended to give improved anchorage while facilitating easier removal of temporary implants. Material and methods: The new surfaces were referenced to a stainless steel implant and a standard titanium implant surface (TiMAX™). In a sheep limb model, healing period was 3 months. Bone-implant bonding was evaluated either biomechanically or histologically. Results: The new surface anodized screws demonstrated similar or slightly higher bone-implantcontact (BIC) and torque release forces than the titanium reference. The BIC of the stainless steel implants was significant lower than two of the anodized surfaces (p=0.04), but differences between stainless steel and all titanium implants in torque release forces were not significant (p=0.06). Conclusion: The new anodized titanium surfaces showed good bone-implant bonding despite a smooth surface and increased nanohardness. However, they failed to facilitate implant removal at 3 months.

scholarly journals A regulatory sub-circuit downstream of Wnt signaling controls developmental transitions in neural crest formation

PLoS Genetics ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. e1009296
Author(s):  
Ana Paula Azambuja ◽  
Marcos Simoes-Costa
Keyword(s):  
Neural Crest ◽  
Cell Fate ◽  
Target Genes ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Stem Cell Population ◽  
Developmental Transitions ◽  
Neural Plate Border ◽  
Sequential Activation ◽  
Fate Restriction

The process of cell fate commitment involves sequential changes in the gene expression profiles of embryonic progenitors. This is exemplified in the development of the neural crest, a migratory stem cell population derived from the ectoderm of vertebrate embryos. During neural crest formation, cells transition through distinct transcriptional states in a stepwise manner. The mechanisms underpinning these shifts in cell identity are still poorly understood. Here we employ enhancer analysis to identify a genetic sub-circuit that controls developmental transitions in the nascent neural crest. This sub-circuit links Wnt target genes in an incoherent feedforward loop that controls the sequential activation of genes in the neural crest lineage. By examining the cis-regulatory apparatus of Wnt effector gene AXUD1, we found that multipotency factor SP5 directly promotes neural plate border identity, while inhibiting premature expression of specification genes. Our results highlight the importance of repressive interactions in the neural crest gene regulatory network and illustrate how genes activated by the same upstream signal become temporally segregated during progressive fate restriction.

scholarly journals Gene expression profiling of epidermal cell types in C. elegans using Targeted-DamID

Development ◽  
2021 ◽  
Author(s):  
Dimitris Katsanos ◽  
Mar Ferrando-Marco ◽  
Iqrah Razzaq ◽  
Gabriel Aughey ◽  
Tony Southall ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Epidermal Cell ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Cell Types ◽  
Specific Gene ◽  
C Elegans ◽  
Seam Cell ◽  
Developmental Progression

The epidermis of Caenorhabditis elegans is an essential tissue for survival as it contributes to the formation of the cuticle barrier, as well as facilitates developmental progression and animal growth. Most of the epidermis consists of the hyp7 hypodermal syncytium, the nuclei of which are largely generated by the seam cells that exhibit stem cell-like behaviour during development. How the seam cell progenitors differ transcriptionally from the differentiated hypodermis is poorly understood. Here, we introduce Targeted DamID (TaDa) in C. elegans as a method for identifying genes expressed within a tissue of interest without cell isolation. We show that TaDa signal enrichment profiles can be used to identify genes transcribed in the epidermis and use this method to resolve differences in gene expression between the seam cells and the hypodermis. We finally predict and functionally validate new transcription and chromatin factors acting in seam cell development. These findings provide insights into cell-type-specific gene expression profiles likely associated with epidermal cell fate patterning.

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