Nonlinear Osmotic Properties of the Cell Nucleus

2009 ◽  
Author(s):  
John D. Finan ◽  
Kevin J. Chalut ◽  
Adam Wax ◽  
Farshid Guilak
Keyword(s):  
Articular Cartilage ◽  
Cell Membrane ◽  
Osmotic Stress ◽  
Biological Function ◽  
Articular Chondrocytes ◽  
Underlying Mechanism ◽  
Osmotic Sensitivity ◽  
Fixed Charges ◽  
Dissolved Ions ◽  
Osmotic Properties

Osmotic stress affects biological function in articular chondrocytes and plays an important role in mechanotransduction in articular cartilage. One potential pathway for osmotic sensitivity in chondrocytes is direct deformation of the nucleus by osmotic stress [1,2]. However, the mechanism of this phenomenon is currently unclear. The nucleus is not contained within a semi-permeable lipid bilayer as are most osmotically sensitive organelles. It is conceivable that fixed charges in chromatin might attract dissolved ions and render it osmotically sensitive. However, this model cannot account for the abolition of the osmotic sensitivity of the nucleus by permeabilization of the cell membrane [3]. The goal of this study was to characterize the osmotic sensitivity of the chondrocyte nucleus and determine the underlying mechanism.

Osmotic Stress Affects Nuclear Morphology and Genome Architecture

2009 ◽  
Author(s):  
John D. Finan ◽  
Farshid Guilak
Keyword(s):  
Osmotic Stress ◽  
Mammalian Cells ◽  
Spatial Organization ◽  
Monolayer Culture ◽  
Articular Chondrocytes ◽  
Spatial Arrangement ◽  
Adherent Cells ◽  
Nuclear Deformation ◽  
Osmotic Sensitivity ◽  
Actin Organization

The spatial organization of the genome influences its function [1]. Therefore, physical signals that deform the nucleus and the genome within may directly affect gene transcription and translation. In articular chondrocytes, nuclear deformation in response to osmotic stress is not sensitive to actin organization [2]. However, articular chondrocytes differ from most mammalian cells in that they remain round with cortically organized actin in monolayer culture. Adherent cells such as adipose stem cells (ASCs) spread in monolayer culture, forming a more typical, highly bundled actin cytoskeleton. These actin bundles exert tensile stress on the nucleus so we hypothesized that the osmotic sensitivity of the cell nucleus would be modulated by actin organization in ASCs. The osmotic sensitivity of the nucleus was quantified by measuring changes in the size and shape of the nucleus and the spatial arrangement of the chromatin within using 3D confocal microscopy.

Light Chain LC and TAT-EGFP-HCS of Botulinum Toxin Expression and Biological Function in vitro and in vivo

2019 ◽  
Vol 16 (3) ◽  
pp. 175-180
Author(s):  
Fengjin Hao ◽  
Yueqin Feng ◽  
Yifu Guan
Keyword(s):  
Biological Activity ◽  
Botulinum Toxin ◽  
Cell Membrane ◽  
Western Blot ◽  
Biological Function ◽  
C6 Cells ◽  
Green Fluorescence ◽  
Bv2 Cells

Objective: To verify whether the botulinum toxin heavy chain HCS has specific neuronal targeting function and to confirm whether TAT-EGFP-LC has hydrolyzable SNAP-25 and has transmembrane biological activity. Methods: We constructed the pET-28a-TAT-EGFP-HCS/LC plasmid. After the plasmid is expressed and purified, we co-cultured it with nerve cells or tumors. In addition, we used Western-Blot to identify whether protein LC and TAT-EGFP-LC can digest the protein SNAP-25. Results: Fluorescence imaging showed that PC12, BV2, C6 and HeLa cells all showed green fluorescence, and TAT-EGFP-HCS had the strongest fluorescence. Moreover, TAT-EGFP-LC can hydrolyze intracellular SNAP-25 in PC12 cells, C6 cells, BV2 cells and HeLa, whereas LC alone cannot. In addition, the in vivo protein TAT-EGFP-HCS can penetrate the blood-brain barrier and enter mouse brain tissue. Conclusion: TAT-EGFP-HSC expressed in vitro has neural guidance function and can carry large proteins across the cell membrane without influencing the biological activity.

Finite Element Modeling of Osmotic Swelling in Tissue-Engineered Cartilage

2008 ◽  
Author(s):  
Liming Bian ◽  
Terri Ann N. Kelly ◽  
Eric G. Lima ◽  
Gerard A. Ateshian ◽  
Clark T. Hung
Keyword(s):  
Articular Cartilage ◽  
Potential Role ◽  
Swelling Pressure ◽  
Type Ii Collagen ◽  
Type Ii ◽  
Osmotic Swelling ◽  
Fixed Charges ◽  
Central Regions ◽  
Significant Research ◽  
Engineered Cartilage

Proteoglycans and Type II collagen represent the two major biochemical constituents of articular cartilage. Collagen fibrils in cartilage resist the swelling pressure that arises from the fixed charges of the glycosaminoglycans (GAGs), and together they give rise to the tissue’s unique load bearing properties. As articular cartilage exhibits a poor intrinsic healing capacity, there is significant research in the development of cell-based therapies for cartilage repair. In some of our tissue engineering studies, we have observed a phenomenon where chondrocyte-seeded hydrogel constructs display cracking in their central regions after significant GAG content has been elaborated in culture. A theoretical analysis was performed to gain greater insights into the potential role that the spatial distribution of proteoglycan and collagen may play in this observed response.

scholarly journals The ciliary protein IFT88 controls post-natal cartilage thickness and influences development of osteoarthritis

2020 ◽  
Author(s):  
CR Coveney ◽  
L Zhu ◽  
J Miotla-Zarebska ◽  
B Stott ◽  
I Parisi ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Cell Biology ◽  
Articular Chondrocytes ◽  
Skeletal Development ◽  
Cartilage Degradation ◽  
Cartilage Thickness ◽  
Tissue Growth ◽  
Calcified Cartilage ◽  
Health And Disease

AbstractMechanical forces are known to drive cellular signalling programmes in cartilage development, health, and disease. Proteins of the primary cilium, implicated in mechanoregulation, control cartilage formation during skeletal development, but their role in post-natal cartilage is unknown. Ift88fl/fl and AggrecanCreERT2 mice were crossed to create a cartilage specific inducible knockout mouse AggrecanCreERT2;Ift88fl/fl. Tibial articular cartilage thickness was assessed, through adolescence and adulthood, by histomorphometry and integrity by OARSI score. In situ cell biology was investigated by immunohistochemistry (IHC) and qPCR of micro-dissected cartilage. OA was induced by destabilisation of the medial meniscus (DMM). Some mice were provided with exercise wheels in their cage. Deletion of IFT88 resulted in a reduction in medial articular cartilage thickness (atrophy) during adolescence from 102.57μm, 95% CI [94.30, 119.80] in control (Ift88fl/fl) to 87.36μm 95% CI [81.35, 90.97] in AggrecanCreERT2;Ift88fl/fl by 8-weeks p<0.01, and adulthood (104.00μm, 95% CI [100.30, 110.50] in Ift88fl/fl to 89.42μm 95% CI [84.00, 93.49] in AggrecanCreERT2;Ift88fl/fl, 34-weeks, p<0.0001) through a reduction in calcified cartilage. Thinning in adulthood was associated with spontaneous cartilage degradation. Following DMM, AggrecanCreERT2;Ift88fl/fl mice had increased OA (OARSI scores at 12 weeks Ift88fl/fl = 22.08 +/− 9.30, and AggrecanCreERT2;Ift88fl/fl = 29.83 +/− 7.69). Atrophy was not associated with aggrecanase-mediated destruction or chondrocyte hypertrophy. Ift88 expression positively correlated with Tcf7l2 and connective tissue growth factor. Cartilage thickness was restored in AggrecanCreERT2;Ift88fl/fl by voluntary wheel exercise. Our results demonstrate that ciliary IFT88 regulates cartilage thickness and is chondroprotective, potentially through modulating mechanotransduction pathways in articular chondrocytes.

Articular Cartilage Fragmentation Improves Chondrocyte Migration by Upregulating Membrane Type 1 Matrix Metalloprotease

Cartilage ◽  
2021 ◽  
pp. 194760352110354
Author(s):  
Yunliang Lei ◽  
Jiabin Peng ◽  
Zhu Dai ◽  
Ying Liao ◽  
Quanhui Liu ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Articular Chondrocytes ◽  
Laser Scanning Microscopy ◽  
Gelatin Sponge ◽  
Confocal Laser ◽  
Matrix Metalloprotease ◽  
Membrane Type ◽  
Chondrocyte Migration

Objective This study was undertaken to elucidate the mechanism of improved chondrocyte migration after juvenile articular cartilage fragmentation. Design In vitro organ culture with rabbit cartilage fragments and cell culture with rabbit chondrocytes were performed. In part A, minced juvenile cartilage fragments (~0.5 × 0.5 × 0.5 mm) from rabbits, planted in gelatin sponge and fibrin glue, were cultured for 2, 4, or 6 weeks in vitro and compared with the cartilage chunks (~4 × 4 × 1 mm) and membrane type 1 matrix metalloprotease (MT1-MMP) inhibitor groups. Chondrocyte outgrowth was evaluated on histology and confocal laser scanning microscopy. MT1-MMP expression was compared between the cartilage fragment group and the cartilage chunks group. In part B, articular chondrocytes were harvested from juvenile rabbits, MT1-MMP was transfected into the cells, and cell migration was evaluated using the Transwell and wound healing tests. Results The histology and confocal microscopy results revealed that cell accumulation occurred at the edge of cartilage fragments, and outgrowth was better in the cartilage fragment group than those in the cartilage chunks group. Similar results were observed for MT1-MMP expression. After MT1-MMP inhibition, cells did not accumulate at the edge of the cartilage fragments, and chondrocyte outgrowth did not occur. Furthermore, overexpression of MT1-MMP enhanced the migration of articular chondrocytes. Conclusions Juvenile articular cartilage fragmentation improved chondrocyte migration by upregulating MT1-MMP.

Phenotypic maintenance of articular chondrocytes in vitro requires BMP activity

2007 ◽  
Vol 20 (03) ◽  
pp. 185-191 ◽  
Author(s):  
A. O. Oshin ◽  
E. Caporali ◽  
C. R. Byron ◽  
A. A. Stewart ◽  
M. C. Stewart
Keyword(s):  
Articular Cartilage ◽  
Collagen Type ◽  
Articular Chondrocytes ◽  
Soluble Form ◽  
Mrna Levels ◽  
Type Ii ◽  
Collagen Type Ii ◽  
Endogenous Expression ◽  
Chondrocytic Phenotype

SummaryArticular chondrocytes are phenotypically unique cells that are responsible for the maintenance of articular cartilage. The articular chondrocytic phenotype is influenced by a range of soluble factors. In particular, members of the bone morphogenetic protein (BMP) family support the articular chondrocytic phenotype and stimulate synthesis of cartilaginous matrix. This study was carried out to determine the importance of BMPs in supporting the differentiated phenotype of articular chondrocytes in vitro. Exogenous BMP-2 supported expression of collagen type II and aggrecan in monolayer chondrocyte cultures, slowing the dedifferentiation process that occurs under these conditions. In contrast, BMP-2 had little effect on expression of these genes in three-dimensional aggregate cultures. Endogenous BMP-2 expression was lost in monolayer cultures, coincident with the down-regulation of collagen type II and aggrecan mRNAs, whereas BMP-2 mRNA levels were stable in aggregate cultures. Antagonism of endogenous BMP activity in aggregate cultures by Noggin or a soluble form of the BMP receptor resulted in reduced expression of collagen type II and aggrecan mRNAs, reduced collagen type II protein and sulfated glycosaminoglycan (GAG) deposition into the aggregate matrices and reduced secretion of GAGs into the culture media. These results indicate that endogenous BMPs are required for maintenance of the differentiated articular chondrocytic phenotype in vitro. These findings are of importance to cell-based strategies designed to repair articular cartilage. Articular chondrocytes require conditions that will support endogenous expression of BMPs to maintain the specialized phenotype of these cells.

scholarly journals Antibacterial Activity and Mechanism of Ginger Essential Oil against Escherichia coli and Staphylococcus aureus

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3955 ◽  
Author(s):  
Xin Wang ◽  
Yi Shen ◽  
Kiran Thakur ◽  
Jinzhi Han ◽  
Jian-Guo Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Essential Oil ◽  
Cell Membrane ◽  
Bacterial Cell ◽  
Tricarboxylic Acid Cycle ◽  
Inhibition Zone ◽  
Underlying Mechanism ◽  
Bacterial Suspension

Though essential oils exhibit antibacterial activity against food pathogens, their underlying mechanism is understudied. We extracted ginger essential oil (GEO) using supercritical CO2 and steam distillation. A chemical composition comparison by GC-MS showed that the main components of the extracted GEOs were zingiberene and α-curcumene. Their antibacterial activity and associated mechanism against Staphylococcus aureus and Escherichia coli were investigated. The diameter of inhibition zone (DIZ) of GEO against S. aureus was 17.1 mm, with a minimum inhibition concentration (MIC) of 1.0 mg/mL, and minimum bactericide concentration (MBC) of 2.0 mg/mL. For E. coli, the DIZ was 12.3 mm with MIC and MBC values of 2.0 mg/mL and 4.0 mg/mL, respectively. The SDS-PAGE analysis revealed that some of the electrophoretic bacterial cell proteins bands disappeared with the increase in GEO concentration. Consequently, the nucleic acids content of bacterial suspension was raised significantly and the metabolic activity of bacteria was markedly decreased. GEO could thus inhibit the expression of some genes linked to bacterial energy metabolism, tricarboxylic acid cycle, cell membrane-related proteins, and DNA metabolism. Our findings speculate the bactericidal effects of GEO primarily through disruption of the bacterial cell membrane indicating its suitability in food perseveration.

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