c-Krox down-regulates the expression of UDP-glucose dehydrogenase in chondrocytes.
Chondrocyte glycosaminoglycan (GAG) synthesis is regulated by the availability of UDP-glucuronate, the substrate of glucuronosyl transferases which form the GAG chains in proteoglycans and hyaluronan. UDP-glucose dehydrogenase (UDPGD) is therefore a key enzyme in the synthesis of UDP-glucuronate from glucose. However, the mechanisms regulating its expression in chondrocytes are not fully understood. We investigated the effect of c-Krox, a zinc-finger transcription factor previously shown to modulate several matrix genes, on the synthesis of GAG and transcriptional activity of several UDPGD gene promoter constructs, using transient transfection and decoy experiments in rabbit articular chondrocytes (RACs). We show that overexpression of c-Krox inhibits radiosulfate incorporation into neosynthesized GAG and that the effect was mediated by a cis-sequence located between +18 and +39bp of the UDPGD gene. Since that sequence can also bind Sp1/Sp3 factors, it is likely that c-Krox acts in concert with these proteins to modulate the UDPGD gene expression in articular chondrocytes.
Laboratory of Connective Tissue Biochemistry, Faculty of Medicine, Caen, France.
Gallic
G
Beauchef
Magdalini
M
Kypriotou
Christos
C
Chadjichristos
Russell L
RL
Widom
Benoît
B
Porée
Emmanuelle
E
Renard
Safa
S
Moslemi
Yanusz
Y
Wegrowski
François-Xavier
FX
Maquart
Jean-Pierre
JP
Pujol
Philippe
P
Galéra
D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006025:Glycosaminoglycans / Q000378:metabolism*; D011817:Rabbits; D011994:Recombinant Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014533:Uridine Diphosphate Glucose Dehydrogenase / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D006025:Glycosaminoglycans; D011994:Recombinant Proteins; D014157:Transcription Factors; C484225:ZBTB7B protein, human; D014533:Uridine Diphosphate Glucose Dehydrogenase