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Basement membrane components in the chondrocyte extracellular matrix

Kvist, Alexander LU (2007)
Abstract (Swedish)
Popular Abstract in Swedish

In conclusion we show that basement membrane components are present in cartilage ECM and that they may serve roles both as BM functional equivalents as well as organizational roles during ECM formation.



Den extracellulära matrixen (ECM) är ett nätverk av makromolekyler som, tillsammans med celler, bildar de olika vävnaderna I alla organismer från phylum metazoa. Till skillnad från de flesta andra vävnadstyper så innehåller brosk relativt få celler i jämnförelse med den volym som uptas av ECM. En del av detta arbete innefattar en undersökning av brosk ECM för uttryck och secretion av de proteiner som anses vara defenierande för en specialiserad ECM struktur, känd som... (More)
Popular Abstract in Swedish

In conclusion we show that basement membrane components are present in cartilage ECM and that they may serve roles both as BM functional equivalents as well as organizational roles during ECM formation.



Den extracellulära matrixen (ECM) är ett nätverk av makromolekyler som, tillsammans med celler, bildar de olika vävnaderna I alla organismer från phylum metazoa. Till skillnad från de flesta andra vävnadstyper så innehåller brosk relativt få celler i jämnförelse med den volym som uptas av ECM. En del av detta arbete innefattar en undersökning av brosk ECM för uttryck och secretion av de proteiner som anses vara defenierande för en specialiserad ECM struktur, känd som basalmembran (BM). Vi visar att de fyra definierande komponenterna av BM, lamininer, type IV kollagen, perlecan och nidogener utrycks i brosk. Vidare så visar vi att dessa proteiner lokaliserar specifikt till kondrocyternas pericellulära matrix och vi föreslår att de här bildar den funktionella ekvivalenten till ett basalmembran. Perlecan, som beskrivet ovan, är en av de definierande komponenterna av BM. Fibulin, ett annat protein som återfinns i både brosk och BM, har tidigare visats vara inblandad i organisationen av brosk ECM. Vi undersökte därför om även perlecan kunde ha en roll i brosk ECM organisation. Vi upptäckte att en specific glykosilerings variant av perlecan stimulerade kollagen fibril bildning. Vi visar även att socker kedjan kondroitin sulfat från perlecan kunde stimulera fibril bildning oberoende av core-proteinet. Undersökning av kondroitin sulfatets sammansättning visade att det var berikat med högsulfaterade E-typ disakarider (CS-E) och vi hävdar därmed att denna specifika sulfaterings variant av kondroitin sulfat är ansvarig för stimulering av kollagen fibril bildning. Vi undersöker även mechanismen för stimuleringen och visar att den sker genom en icke-tvärbindande process som inte inhiberas av et överskott av icke-stimulerande glycosaminoglykaner. Heparin delar flera biologiska egenskaper med CS-E och stimulerar även detta fibril bildning. Concentrationen av heparin i jämförelse med CS-E, för att uppnå samma stimulerings-grad, var däremot väldigt mycket lägre. Andra skillnader var att heparin fragment ända ner till heptamerer stimulerade fibrillering medans all fragmentering av CS-E ledde till förlust av den stimulerande effekten.



Sammanfattningsvis så har vi visat att alla defenierande komponenter av basalmembran finns i brosk ECM och att de har roller både som den funktionella ekvivalenten av ett basalmembran och i organisationen av brosk ECM. (Less)
Abstract
The extracellular matrix (ECM) is a network of macromolecules which, together with cells, forms the various tissues of all metazoan organisms. Cartilage, in contrast to most other tissues, contains relatively few cells in proportion to the volume occupied by ECM. Part of this work involves investigation of cartilage ECM for expression and secretion of proteins that are considered to be the defining components of a specialized ECM known as a basement membrane (BM). We show that indeed all the four defining components of BMs, laminins, type IV collagen, perlecan and nidogens are expressed in cartilage. Furthermore, we show that these proteins localise to the chondrcyte pericellular matrix, where we suggest they form the functional equivalent... (More)
The extracellular matrix (ECM) is a network of macromolecules which, together with cells, forms the various tissues of all metazoan organisms. Cartilage, in contrast to most other tissues, contains relatively few cells in proportion to the volume occupied by ECM. Part of this work involves investigation of cartilage ECM for expression and secretion of proteins that are considered to be the defining components of a specialized ECM known as a basement membrane (BM). We show that indeed all the four defining components of BMs, laminins, type IV collagen, perlecan and nidogens are expressed in cartilage. Furthermore, we show that these proteins localise to the chondrcyte pericellular matrix, where we suggest they form the functional equivalent of a basement membrane.



Perlecan, as stated previously, is one of the cardinal components of BMs. Fibulin, another protein found both in basement membranes and cartilage, has previously been found to be involved in organization of the cartilage ECM. A further aim of this work was therefore to investigate any role that perlecan plays in cartilage ECM organization. we show that a specific glycosilation variant of perlecan potently stimulates collagen fibril formation. We further show that stimulation can be accomplished by the specific Chondroitin sulfate (CS) chain of perlecan, independently of the core protein. Investigation of the CS chain composition reveals that it is enriched in a specific high sulfation disaccharide (CS-E) and we postulate that this high sulfation CS-chain is necessary for collagen fibril formation stimulation. We also continue to investigate the mechanism by which stimulation is accomplished and show that stimulation is accomplished through a non-crossbridging mechanism that cannot be inhibited by an excess of non-stimulatory glycosaminoglycan. Heparin, which shares biological characteristics with the high sulfation CS-E, also stimulates fibril formation. The efficacy of heparin is however significantly higher and further differences include the ability of heparin fragments as small as heptamers to stimulate fibril formation while CS-E fragments appear to lose their stimulatory traits upon even partial digestion.



In conclusion we show that basement membrane components are present in cartilage ECM and that they may serve roles both as BM functional equivalents as well as organizational roles during ECM formation. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Kadler, Karl, University of Manchester
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Skelett, rheumatology locomotion, nidogen, chondroitin sulfate, collagen assembly, Skeleton, muscle system, type IV collagen, laminin, perlecan, basement membranes, ECM, chondrcytes, muskelsystem, reumatologi
pages
148 pages
publisher
Lund University, Faculty of Medicine
defense location
Sölvegatan 19, BMC, GK-salen, Lund
defense date
2007-06-09 09:00
ISSN
1652-8220
ISBN
978-91-85559-95-4
language
English
LU publication?
yes
id
b297c93e-414e-450d-989e-6384541e7336 (old id 548765)
date added to LUP
2007-09-12 08:27:37
date last changed
2016-09-19 08:44:59
@phdthesis{b297c93e-414e-450d-989e-6384541e7336,
  abstract     = {The extracellular matrix (ECM) is a network of macromolecules which, together with cells, forms the various tissues of all metazoan organisms. Cartilage, in contrast to most other tissues, contains relatively few cells in proportion to the volume occupied by ECM. Part of this work involves investigation of cartilage ECM for expression and secretion of proteins that are considered to be the defining components of a specialized ECM known as a basement membrane (BM). We show that indeed all the four defining components of BMs, laminins, type IV collagen, perlecan and nidogens are expressed in cartilage. Furthermore, we show that these proteins localise to the chondrcyte pericellular matrix, where we suggest they form the functional equivalent of a basement membrane.<br/><br>
<br/><br>
Perlecan, as stated previously, is one of the cardinal components of BMs. Fibulin, another protein found both in basement membranes and cartilage, has previously been found to be involved in organization of the cartilage ECM. A further aim of this work was therefore to investigate any role that perlecan plays in cartilage ECM organization. we show that a specific glycosilation variant of perlecan potently stimulates collagen fibril formation. We further show that stimulation can be accomplished by the specific Chondroitin sulfate (CS) chain of perlecan, independently of the core protein. Investigation of the CS chain composition reveals that it is enriched in a specific high sulfation disaccharide (CS-E) and we postulate that this high sulfation CS-chain is necessary for collagen fibril formation stimulation. We also continue to investigate the mechanism by which stimulation is accomplished and show that stimulation is accomplished through a non-crossbridging mechanism that cannot be inhibited by an excess of non-stimulatory glycosaminoglycan. Heparin, which shares biological characteristics with the high sulfation CS-E, also stimulates fibril formation. The efficacy of heparin is however significantly higher and further differences include the ability of heparin fragments as small as heptamers to stimulate fibril formation while CS-E fragments appear to lose their stimulatory traits upon even partial digestion.<br/><br>
<br/><br>
In conclusion we show that basement membrane components are present in cartilage ECM and that they may serve roles both as BM functional equivalents as well as organizational roles during ECM formation.},
  author       = {Kvist, Alexander},
  isbn         = {978-91-85559-95-4},
  issn         = {1652-8220},
  keyword      = {Skelett,rheumatology locomotion,nidogen,chondroitin sulfate,collagen assembly,Skeleton,muscle system,type IV collagen,laminin,perlecan,basement membranes,ECM,chondrcytes,muskelsystem,reumatologi},
  language     = {eng},
  pages        = {148},
  publisher    = {Lund University, Faculty of Medicine},
  school       = {Lund University},
  title        = {Basement membrane components in the chondrocyte extracellular matrix},
  year         = {2007},
}