Latent transforming growth factor-beta is produced by chondrocytes and activated by extracellular matrix vesicles upon exposure to 1,25-(OH)2D3.
Resting zone and growth zone (GC) costochondral chondrocytes constitutively release latent, but not active, transforming growth factor-beta (TGF-beta) into the culture medium. When exogenous TGF-beta is added to the culture medium, no autocrine effect is observed. However, when 1,25-(OH)2D3 is added, a dose-dependent inhibition of latent TGF-beta release is found. Messenger RNA levels for TGF-beta 1 are unchanged by treatment with either 1,25-(OH)2D3 or TGF-beta 1. Since active growth factor was not observed in the conditioned medium, we tested the hypothesis that latent TGF-beta could be activated in the matrix. GC matrix vesicles, extracellular organelles associated with matrix calcification, were able to activate latent TGF-beta 1 and TGF-beta 2 when preincubated with 1,25-(OH)2D3. In contrast, GC plasma membranes activated latent TGF-beta, and addition of 1,25-(OH)2D3 inhibited this activation. The 1,25-(OH)2D3-dependent decrease in latent TGF-beta in the medium, with no detectable change in mRNA level, and the inhibition of plasma membrane activation of latent TGF-beta by 1,25-(OH)2D3 suggest that 1,25-(OH)2D3 may act through post-transcriptional and/or nongenomic mechanisms. The results also suggest that latent TGF-beta is activated in the matrix and that 1,25-(OH)2D3 regulates this activation by a direct, nongenomic action on the matrix vesicle membrane.
Department of Orthopaedics, University of Texas Health Science Center, San Antonio 78284.
B D
BD
Boyan
Z
Z
Schwartz
S
S
Park-Snyder
D D
DD
Dean
F
F
Yang
D
D
Twardzik
L F
LF
Bonewald
D015650:24,25-Dihydroxyvitamin D 3 / Q000494:pharmacology; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004247:DNA / Q000096:biosynthesis; D005109:Extracellular Matrix / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008168:Lung; D008907:Mink; D015388:Organelles / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000096:biosynthesis* / Q000494:pharmacology*
D017077:Culture Media, Conditioned; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D015650:24,25-Dihydroxyvitamin D 3; D004247:DNA; D000469:Alkaline Phosphatase; D002117:Calcitriol; D013936:Thymidine