Analysis of fracture healing by large-scale transcriptional profile identified temporal relationships between metalloproteinase and ADAMTS mRNA expression.
The aim of this study was to validate the use of transcriptional profiling as a means of characterizing the complex interactions of the thousands of genes that are expressed during fracture healing. Standard mid-diaphyseal tibia fractures were generated in C57/B6 murine tibiae and the transcriptional expression of approximately 13,000 genes was assessed. Three time points after fracture were assessed: day 3, representative of the inflammatory phase; day 10, representative of the peak of cartilage formation; and day 21, representative of the period of primary bone formation and coupled remodeling. A self-organizing mapping approach of the data revealed the temporal relationships between the expression of mRNAs for extracellular matrix proteins and the proteases that degrade the proteoglycan and collagenous matrices. A broad group of extracellular matrix protein mRNAs representative of basement membranes, blood vessels and cartilage all showed elevated expression over the first 21 days of fracture healing. The sorting of the data identified an orderly temporal expression of the metalloproteinases and ADAMTS during the progression of fracture healing with (MMP2/MMP14/TIMP2) and ADAMTS4 and 15 preceding the expression of (MMP9/MMP13). Based on their patterns of expression, relative to the known activities of the encoded proteolytic enzymes, our results suggest that the dissolution of cartilage protoeglycans proceeds before the underlying collagenous components of the matrix are removed. The exclusion of several mRNAs that are normally expressed by osteoclasts in the profiles of mRNAs from days 3 and 10 suggests that osteoclastic activity was largely absent during the early periods of cartilage tissue formation and that proteoglycan and specific collagenase activities, precedes or is prerequisite to later osteoclast infiltration into the remodeling tissues.
Department of Orthopaedic Surgery, Orthopaedic Research Laboratory, Boston University Medical Center, Boston, MA 02118, USA.
Kevin
K
Wang
Prashanth
P
Vishwanath
Gabriel S
GS
Eichler
Maisa O
MO
Al-Sebaei
Cory M
CM
Edgar
Thomas A
TA
Einhorn
Temple F
TF
Smith
Louis C
LC
Gerstenfeld
D051722:ADAM Proteins / Q000235:genetics*; D000071121:ADAMTS4 Protein; D000818:Animals; D001483:Base Sequence; D017364:Collagenases / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D017102:Fracture Healing / Q000235:genetics* / Q000502:physiology; D020869:Gene Expression Profiling; D008297:Male; D053509:Matrix Metalloproteinase 13; D053511:Matrix Metalloproteinase 14; D020778:Matrix Metalloproteinase 2 / Q000235:genetics; D020780:Matrix Metalloproteinase 9 / Q000235:genetics; D020782:Matrix Metalloproteinases / Q000235:genetics; D053504:Matrix Metalloproteinases, Membrane-Associated; D045726:Metalloproteases / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis; D011348:Procollagen N-Endopeptidase / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D017931:DNA Primers; C507096:Mmp14 protein, mouse; D012333:RNA, Messenger; D045726:Metalloproteases; D051722:ADAM Proteins; D017364:Collagenases; D053509:Matrix Metalloproteinase 13; D020782:Matrix Metalloproteinases; D053504:Matrix Metalloproteinases, Membrane-Associated; C507081:Mmp13 protein, mouse; D011348:Procollagen N-Endopeptidase; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D053511:Matrix Metalloproteinase 14; D000071121:ADAMTS4 Protein; C000603919:Adamts4 protein, mouse