Collagen fibril assembly by corneal fibroblasts in three-dimensional collagen gel cultures: small-diameter heterotypic fibrils are deposited in the absence of keratan sulfate proteoglycan.
Extracellular matrix assembly is a multistep process and the various steps in collagen fibrillogenesis are thought to be influenced by a number of factors, including other noncollagenous matrix molecules. The synthesis and deposition of extracellular matrix by corneal fibroblasts grown within three-dimensional collagen gel cultures were examined to elucidate the factors important in the establishment of tissue-specific matrix architecture. Corneal fibroblasts in collagen gel cultures form layers and deposit small-diameter collagen fibrils (approximately 25 nm) typical of the mature corneal stroma. The matrix synthesized contains type VI collagen in a filamentous network and type I and type V collagen assembled as heterotypic fibrils. The amount of type V collagen synthesized is relatively high and comparable to that seen in the corneal stroma. This matrix is deposited between cell layers in a manner reminiscent of the secondary corneal stroma, but is not deposited as densely or as organized as would be found in situ. No keratan sulfate proteoglycan, a proteoglycan found only in the corneal stroma, was synthesized by the fibroblasts in the collagen gel cultures. The assembly and deposition of small-diameter fibrils with a collagen composition and structure identical to that seen in the corneal stroma in the absence of proteoglycans typical of the secondary corneal stroma imply that although proteoglycan-collagen interactions may function in the establishment of interfibrillar spacing and lamellar organization, collagen-collagen interactions are the major parameter in the regulation of fibril diameter.
Doane
K J
KJ
Department of Pathology, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635.
Babiarz
J P
JP
Fitch
J M
JM
Linsenmayer
T F
TF
Birk
D E
DE
D000818:Animals; D000911:Antibodies, Monoclonal; D002478:Cells, Cultured; D002642:Chick Embryo; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism*; D003094:Collagen / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism*; D046508:Culture Techniques / Q000379:methods; D005109:Extracellular Matrix / Q000502:physiology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D005998:Glycine / Q000378:metabolism; D007632:Keratan Sulfate / Q000378:metabolism*; D000071234:Lumican; D008854:Microscopy, Electron; D009924:Organ Culture Techniques; D011392:Proline / Q000378:metabolism; D011509:Proteoglycans / Q000096:biosynthesis
D000911:Antibodies, Monoclonal; D011508:Chondroitin Sulfate Proteoglycans; D000071234:Lumican; D011509:Proteoglycans; D003094:Collagen; D007632:Keratan Sulfate; D011392:Proline; D005998:Glycine