ISSLS prize winner: LMP-1 upregulates intervertebral disc cell production of proteoglycans and BMPs in vitro and in vivo.
METHODS
Experiments using both in vitro tissue culture and in vivo rabbit methods were used to study the effect of Lim Mineralization Protein-1 (LMP-1) on intervertebral disc (IVD) cell production of proteoglycans and bone morphogenetic proteins (BMPs).


OBJECTIVE
To determine the effect of LMP-1 overexpression in IVD cells on the production of proteoglycans and BMPs both in vitro and in vivo and to show that LMP-1 mediates the control of proteoglycan production through its action on BMPs.


BACKGROUND
Because BMPs are known to increase proteoglycan synthesis and LMP-1 is known to upregulate BMPs in certain cells, it was hypothesized that LMP-1 may increase proteoglycan production in IVD cells.


METHODS
DMMB, real-time polymerase chain reaction, and ELISA methods were used to quantitate proteoglycan, mRNA, and protein levels, respectively. Noggin was used to block the effect of the adenovirus carrying LMP-1 (AdLMP-1) on proteoglycan synthesis. In vivo experiments using intradiscal AdLMP-1 injection were performed with New Zealand White rabbits. Three weeks later, the mRNA levels of LMP-1, aggrecan, BMP-2, and BMP-7 were measured.


RESULTS
In vitro experiments revealed that the sulfated glycosaminoglycan (sGAG) and aggrecan mRNA levels were significantly increased with AdLMP-1 treatment. Similarly, BMP-2 and BMP-7 mRNA and protein levels increased significantly, but BMP-4 and BMP-6 levels were unchanged. Noggin blocked the upregulation of proteoglycan by AdLMP-1. In vivo discs injected with AdLMP-1 had significantly elevated levels of LMP-1, BMP-2, and BMP-7 mRNA.


CONCLUSIONS
LMP-1 overexpression increases disc cell production of proteoglycan, BMP-2, and BMP-7. LMP-1 mediates the control of proteoglycan production through its action on BMP.
Yoon
Sangwook Tim
ST
Department of Orthopaedic Surgery, Emory University School of Medicine, Atlanta, GA, USA. tim_yoon@emoryhealthcare.org
Park
Jin Soo
JS
Kim
Keun S
KS
Li
Jun
J
Attallah-Wasif
Emad Samir
ES
Hutton
William C
WC
Boden
Scott D
SD
D048868:Adaptor Proteins, Signal Transducing; D000256:Adenoviridae / Q000235:genetics; D053674:Aggrecans; D000818:Animals; D001363:Awards and Prizes; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D004195:Disease Models, Animal; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors; D006025:Glycosaminoglycans / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007403:Intervertebral Disc / Q000187:drug effects* / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000494:pharmacology*; D060588:LIM Domain Proteins; D037181:Lectins, C-Type / Q000235:genetics / Q000378:metabolism; D009985:Orthopedics; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
C508321:Acan protein, rat; D048868:Adaptor Proteins, Signal Transducing; D053674:Aggrecans; C525718:BMP2 protein, human; C525819:BMP7 protein, human; C525720:Bmp2 protein, rat; C525821:Bmp7 protein, rat; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D003598:Cytoskeletal Proteins; D016326:Extracellular Matrix Proteins; D006025:Glycosaminoglycans; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D037181:Lectins, C-Type; C484380:PDLIM7 protein, human; D011509:Proteoglycans; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; C013786:A73025