Mechanical Loading and Articular Cartilage Metabolism

2000 ◽  
Author(s):  
Robert Lane Smith
Keyword(s):  
Articular Cartilage ◽  
Matrix Proteins ◽  
Structural Elements ◽  
Post Translational Modification ◽  
Form And Function ◽  
Diarthrodial Joints ◽  
The Matrix ◽  
Cartilage Cells ◽  
Specific Proteins ◽  
And Function

Abstract Articular cartilage provides diarthrodial joints with a loading-bearing surface that ensures functional motility. The physical characteristics of articular cartilage originate with the highly organized matrix of extracellular macromolecules that provide structural elements to the tissue. The matrix specialization rests with specific proteins produced by the cartilage cells, the chondrocytes that undergo extensive post-translational modification through addition of sulfated glycosaminoglycan and oligosaccharides. The matrix proteins fall into three major categories, the collagens, the proteoglycans and the glycoproteins, with each group contributing unique properties to cartilage form and function.

Comparative studies of rat liver and sea urchin embryo nuclear matrices: partial fractionation and protein kinase activity distribution

1982 ◽  
Vol 55 (1) ◽  
pp. 189-198
Author(s):  
L. Sevaljevic ◽  
M. Petrovic ◽  
M. Konstantinovic ◽  
K. Krtolica
Keyword(s):  
Protein Kinase ◽  
Sea Urchin ◽  
Rat Liver ◽  
Kinase Activity ◽  
Matrix Proteins ◽  
Protein Kinase Activity ◽  
Structural Elements ◽  
Activity Distribution ◽  
Sea Urchin Embryo ◽  
The Matrix

Rat liver and sea urchin embryo nuclear matrices were found to differ in composition and in the strength of the association of their structural elements. Apart from the qualitative differences in composition, the embryonic matrices retained greater amounts of nuclear proteins and DNA, and were less susceptible to ultrasonic treatment than those of rat liver. They were essentially resistant to mild sonication, by which the rat liver matrix structure was resolved into two distinct fractions, referred to by Berezney (1980) as matricin and ribonucleoprotein (RNP). Both sub-fractions exhibited a protein kinase activity; the phosphorylating capacity of the RNP-associated protein kinases was found to be higher than that of the matricin-bound enzyme. The preferred substrate was among the secondary matrix proteins. In sea urchin embryos, sonication introduced no change in the type and lesion of the matrix proteins phosphorylated by the associated enzyme.

Form and Function of Radioulnar Articular Disc

HAND ◽  
1982 ◽  
Vol os-14 (1) ◽  
pp. 61-66 ◽  
Author(s):  
A. Mohiuddin ◽  
M. Z. Janjua
Keyword(s):  
Articular Cartilage ◽  
Connective Tissue ◽  
Articular Disc ◽  
Medial Border ◽  
Form And Function ◽  
Articular Capsule ◽  
Inner Surface ◽  
And Function

1. The human radioulnar articular disc is a shelf extended medially from articular cartilage on carpal facet of radius. 2. Its medial border is embedded in the wedge of vascular connective tissue which contains fine arcuate ligamentous bands joining the disc to the ulna and articular capsule. 3. The ventral and dorsal borders are loosely attached to short ligaments which go from radius to the inner surface of articular capsule. 4. These arrangements permit radius and disc to rotate on ulna freely during pronation and supination.

scholarly journals Morphological Studies on the Ageing and Osteoarthritis of the Articular Cartilage in C57 Black Mice

2005 ◽  
Vol 13 (1) ◽  
pp. 8-18 ◽  
Author(s):  
K Yamamoto ◽  
T Shishido ◽  
T Masaoka ◽  
A Imakiire
Keyword(s):  
Articular Cartilage ◽  
Golgi Apparatus ◽  
Protein Transport ◽  
Control Group ◽  
Cartilage Sample ◽  
Keratan Sulphate ◽  
Morphological Studies ◽  
Transmission Electron ◽  
The Matrix ◽  
And Function

Purpose. To study the cause and mechanism of joint degeneration in osteoarthritis, through histopathological and ultrastructural-histochemical experiments on the articular cartilage of the knees of the C57 black mouse. Methods. 192 C57 black mice and a control group of 64 C57BL/6J mice were used in this study. The left and right knee articular capsules of the joints were removed and stained. Each articular cartilage sample was examined and osteoarthritic changes were assessed using a transmission electron microscope. The severity of osteoarthritis in the knee joint cartilage of C57 black mice was histologically assessed using a classification system described by Okabe, based on Maier's system. Results. The incidence and the severity of osteoarthritis gradually increased with age; the incidence increased from 20% at 2 months to 80% at 16 months. Irreversible changes appeared at an advanced stage, and the process of degeneration was quite similar to that in human osteoarthritis. Through transmission electron microscopy, we observed poorly developed Golgi apparatus, markedly increased intracellular microfilaments, decreased proteoglycan granules, and broken collagen networks in all stages of osteoarthritis. By contrast, Golgi apparatus and other organelles were well developed in histologically normal mice of all ages. Proteoglycan granules, which mainly consisted of keratan sulphate, were observed; collagen networks were maintained. Conclusion. Disturbed protein transport and sugar synthesis in chondrocytes, caused by the deficient development of the Golgi apparatus, could result in degenerative changes in articular cartilage. The structure and function of the matrix were maintained mainly because of the continued presence of keratan sulphate.

scholarly journals Deciphering the tissue specificity of the protein secretory pathway in humans

2016 ◽  
Author(s):  
Amir Feizi ◽  
Francesco Gatto ◽  
Mathias Uhlen ◽  
Jens Nielsen
Keyword(s):  
Secretory Pathway ◽  
Fine Tuning ◽  
Human Tissues ◽  
Post Translational Modification ◽  
Membrane Proteome ◽  
Systematic Analysis ◽  
Tissue Specific ◽  
Physiological Regulation ◽  
Specific Proteins ◽  
And Function

AbstractProteins that are components of the secretory machinery form a cellular pathway of paramount importance for physiological regulation, development and function of human tissues. Consistently, most secretory pathway components are ubiquitously expressed in all tissues. At the same time, recent studies identified that the largest fraction of tissue-specific proteins consists of secreted and membrane proteins and not intracellular proteins. This suggests that the secretory pathway is distinctively regulated in a tissue-specific fashion. However, a systematic analysis on how the protein secretory pathway is tuned in different tissues is lacking, and it is even largely unexplored if the secretome and membrane proteome differs in, for example, posttranslation modifications across tissues. Here, analyzing publically available transcriptome data across 30 human tissues, we discovered the expression level of key components previously categorized as housekeeping proteins were specifically over-expressed in a certain tissue compared with the average expression of their corresponding secretory pathway subsystem (e.g. protein folding). These extreme genes define an exceptional fine-tuning in specific subnetworks, which neatly differentiated for example the pancreas and liver from 30 other tissues. Moreover, the subnetwork expression tuning correlated with the nature and number of post translational modification sites in the pancreas or liver-specific secretome and membrane proteome. These patterns were recurrently observed also in other tissues, like the blood, the brain and the skeletal muscle. These findings conciliate both the housekeeping and tissue-specific nature of the protein secretory pathway, which we attribute to a fine-tuned regulation of defined subnetworks in order to support the diversity of secreted proteins and their modifications.

scholarly journals Anaerobic peroxisomes in Mastigamoeba balamuthi

2020 ◽  
Vol 117 (4) ◽  
pp. 2065-2075
Author(s):  
Tien Le ◽  
Vojtěch Žárský ◽  
Eva Nývltová ◽  
Petr Rada ◽  
Karel Harant ◽  
...  
Keyword(s):  
Protein Import ◽  
Atp Synthesis ◽  
Matrix Proteins ◽  
Cellular Damage ◽  
Ros Scavenging ◽  
Mitochondrial Derivative ◽  
The Matrix ◽  
Peroxisomal Targeting ◽  
Tightly Coupled ◽  
And Function

The adaptation of eukaryotic cells to anaerobic conditions is reflected by substantial changes to mitochondrial metabolism and functional reduction. Hydrogenosomes belong among the most modified mitochondrial derivative and generate molecular hydrogen concomitant with ATP synthesis. The reduction of mitochondria is frequently associated with loss of peroxisomes, which compartmentalize pathways that generate reactive oxygen species (ROS) and thus protect against cellular damage. The biogenesis and function of peroxisomes are tightly coupled with mitochondria. These organelles share fission machinery components, oxidative metabolism pathways, ROS scavenging activities, and some metabolites. The loss of peroxisomes in eukaryotes with reduced mitochondria is thus not unexpected. Surprisingly, we identified peroxisomes in the anaerobic, hydrogenosome-bearing protist Mastigamoeba balamuthi. We found a conserved set of peroxin (Pex) proteins that are required for protein import, peroxisomal growth, and division. Key membrane-associated Pexs (MbPex3, MbPex11, and MbPex14) were visualized in numerous vesicles distinct from hydrogenosomes, the endoplasmic reticulum (ER), and Golgi complex. Proteomic analysis of cellular fractions and prediction of peroxisomal targeting signals (PTS1/PTS2) identified 51 putative peroxisomal matrix proteins. Expression of selected proteins in Saccharomyces cerevisiae revealed specific targeting to peroxisomes. The matrix proteins identified included components of acyl-CoA and carbohydrate metabolism and pyrimidine and CoA biosynthesis, whereas no components related to either β-oxidation or catalase were present. In conclusion, we identified a subclass of peroxisomes, named “anaerobic” peroxisomes that shift the current paradigm and turn attention to the reductive evolution of peroxisomes in anaerobic organisms.

Myocardial Matrix Remodeling and the Matrix Metalloproteinases: Influence on Cardiac Form and Function

2007 ◽  
Vol 87 (4) ◽  
pp. 1285-1342 ◽  
Author(s):  
Francis G. Spinale
Keyword(s):  
Matrix Metalloproteinases ◽  
Cardiac Disease ◽  
Hypertensive Heart Disease ◽  
Matrix Remodeling ◽  
Myocardial Remodeling ◽  
Form And Function ◽  
Disease States ◽  
The Matrix ◽  
And Function ◽  
Remarkable Progress

It is now becoming apparent that dynamic changes occur within the interstitium that directly contribute to adverse myocardial remodeling following myocardial infarction (MI), with hypertensive heart disease and with intrinsic myocardial disease such as cardiomyopathy. Furthermore, a family of matrix proteases, the matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs), has been recognized to play an important role in matrix remodeling in these cardiac disease states. The purpose of this review is fivefold: 1) to examine and redefine the myocardial matrix as a critical and dynamic entity with respect to the remodeling process encountered with MI, hypertension, or cardiomyopathic disease; 2) present the remarkable progress that has been made with respect to MMP/TIMP biology and how it relates to myocardial matrix remodeling; 3) to evaluate critical translational/clinical studies that have provided a cause-effect relationship between alterations in MMP/TIMP regulation and myocardial matrix remodeling; 4) to provide a critical review and analysis of current diagnostic, prognostic, and pharmacological approaches that utilized our basic understanding of MMP/TIMPs in the context of cardiac disease; and 5) most importantly, to dispel the historical belief that the myocardial matrix is a passive structure and supplant this belief that the regulation of matrix protease pathways such as the MMPs and TIMPs will likely yield a new avenue of diagnostic and therapeutic strategies for myocardial remodeling and the progression to heart failure.

FEISEM, Form and Function in the Nuclear Pore Complex

1998 ◽  
Vol 4 (S2) ◽  
pp. 958-959
Author(s):  
T.D. Allen ◽  
G. R. Bcnnion ◽  
S. A. Rutherford ◽  
E. Kiscleva ◽  
M. W. Goldberg
Keyword(s):  
Nuclear Pore Complex ◽  
Considerable Increase ◽  
Structural Complexity ◽  
Nuclear Pore ◽  
Molecular Architecture ◽  
Structural Elements ◽  
Form And Function ◽  
Import And Export ◽  
And Function ◽  
High Degree

Recent initiatives have resulted in a considerable increase in our understanding of the structure of the nuclear pore complex (NPC). The biochemical factors involved in both import and export have been rapidly characterised, with steady progress in the molecular dissection of the structural elements of the NPC, which is a unit of considerable molecular architecture (MW 125 kD), comprising an estimated 50- 100 different proteins. Despite this progress, the crucial molecular interactions involved in the mechanics of transport through the central transporter of the NPC remain unclear. NPC structure in Diptera, fish, (Fig 1) amphibians, birds and mammals shows a high degree of evolutionary conservation. 3D reconstructions of isolated yeast NPCs, show that the core structure is very similar to ‘higher’ organisms, but peripheral structures may be considerably reduced in structural complexity (1).Individual NPC components have been accessed in FEISEM by a variety of methods, including proteolysis,

Scanning tunneling microscopy (STM) of DNA and RNA

1989 ◽  
Vol 47 ◽  
pp. 34-35
Author(s):  
Patricia G. Arscott ◽  
Gil Lee ◽  
Victor A. Bloomfield ◽  
D. Fennell Evans
Keyword(s):  
Molecular Structures ◽  
Inorganic Materials ◽  
Resolving Power ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Form And Function ◽  
Dna And Rna ◽  
Calf Thymus ◽  
And Function ◽  
The Relationship

STM is one of the most promising techniques available for visualizing the fine details of biomolecular structure. It has been used to map the surface topography of inorganic materials in atomic dimensions, and thus has the resolving power not only to determine the conformation of small molecules but to distinguish site-specific features within a molecule. That level of detail is of critical importance in understanding the relationship between form and function in biological systems. The size, shape, and accessibility of molecular structures can be determined much more accurately by STM than by electron microscopy since no staining, shadowing or labeling with heavy metals is required, and there is no exposure to damaging radiation by electrons. Crystallography and most other physical techniques do not give information about individual molecules.We have obtained striking images of DNA and RNA, using calf thymus DNA and two synthetic polynucleotides, poly(dG-me5dC)·poly(dG-me5dC) and poly(rA)·poly(rU).

Distribution of VLA-5 and VLA-4 fibronectin receptors in human monocytes demonstrated by immunofluorescence, immunocytochemistry, and autoradiography

1993 ◽  
Vol 51 ◽  
pp. 306-307
Author(s):  
Robert Williams ◽  
Che-Hung Lee ◽  
Sara E. Quella ◽  
David M. Harlan ◽  
Yuan-Hsu Kang
Keyword(s):  
Present Report ◽  
Matrix Proteins ◽  
Extracellular Matrices ◽  
Human Monocytes ◽  
Integrin Receptors ◽  
Morphological Evaluation ◽  
The Matrix ◽  
Specific Receptors ◽  
Cytokine Stimulation ◽  
Monocyte Adherence

Monocyte adherence to endothelial or extracellular matrices plays an important role in triggering monocyte activation in extravascular sites of infection, chronic inflammatory disorders, and tissue damage. Migration of monocytes in the tissues involves the response to a chemoattractant and movement by a series of attachments and detachments to the extracellular matrices which are regulated by expression and distribution of specific receptors for the matrix proteins such as fibronectin (FN). The VSAs (very late antigens or beta integrins), a subfamily of the transmembrane heterodimeric integrin receptors, have been thought to play a major role in monocyte adherence to the extracellular matrices and cells. In this subfamily, VLA-5 and VLA-4 are believed to be the most essential integrins mediating monocyte adherence to FN. In the present report, we have established and compared different procedures for morphological evaluation of the expression and distribution of the FN receptors on human monocytes in order to investigate their response to endotoxin or cytokine stimulation.

Designing TIMP (tissue inhibitor of metalloproteinases) variants that are selective metalloproteinase inhibitors

2003 ◽  
Vol 70 ◽  
pp. 201-212 ◽  
Author(s):  
Hideaki Nagase ◽  
Keith Brew
Keyword(s):  
Three Dimensional ◽  
Therapeutic Interventions ◽  
Tissue Inhibitors Of Metalloproteinases ◽  
Structural Basis ◽  
Structural Elements ◽  
Ridge Structure ◽  
Extracellular Matrix Components ◽  
Metalloproteinase Inhibitors ◽  
The Matrix ◽  
A Disintegrin And Metalloproteinase

The tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of the matrix metalloproteinases (MMPs), enzymes that play central roles in the degradation of extracellular matrix components. The balance between MMPs and TIMPs is important in the maintenance of tissues, and its disruption affects tissue homoeostasis. Four related TIMPs (TIMP-1 to TIMP-4) can each form a complex with MMPs in a 1:1 stoichiometry with high affinity, but their inhibitory activities towards different MMPs are not particularly selective. The three-dimensional structures of TIMP-MMP complexes reveal that TIMPs have an extended ridge structure that slots into the active site of MMPs. Mutation of three separate residues in the ridge, at positions 2, 4 and 68 in the amino acid sequence of the N-terminal inhibitory domain of TIMP-1 (N-TIMP-1), separately and in combination has produced N-TIMP-1 variants with higher binding affinity and specificity for individual MMPs. TIMP-3 is unique in that it inhibits not only MMPs, but also several ADAM (a disintegrin and metalloproteinase) and ADAMTS (ADAM with thrombospondin motifs) metalloproteinases. Inhibition of the latter groups of metalloproteinases, as exemplified with ADAMTS-4 (aggrecanase 1), requires additional structural elements in TIMP-3 that have not yet been identified. Knowledge of the structural basis of the inhibitory action of TIMPs will facilitate the design of selective TIMP variants for investigating the biological roles of specific MMPs and for developing therapeutic interventions for MMP-associated diseases.

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