G. Dourado et P. Luvalle, PROXIMAL DNA ELEMENTS MEDIATE REPRESSOR ACTIVITY CONFERRED BY THE DISTAL PORTION OF THE CHICKEN COLLAGEN-X PROMOTER, Journal of cellular biochemistry, 70(4), 1998, pp. 507-516
Collagen X is expressed specifically in hypertrophic chondrocytes with
in cartilage that is undergoing endochondral ossification. The chicken
collagen X gene is transcriptionally regulated, and under the control
of multiple cis elements within the distal promoter region (-4,442 to
-558 base pairs from the transcription start) as well as the proximal
region (- 558 to + 1). Our previous data (LuValle et at., [1993] J..
Cell Biol. 121.1173-1179) demonstrated that the proximal sequence dire
cted high reporter gene activity in the three cell types tested (hyper
trophic chondrocytes, immature chondrocytes, and fibroblasts), while d
istal elements acted in an additive manner to repress the effects of t
he proximal sequence on reporter gene activity in non-collagen X expre
ssing cells only (immature chondrocytes and fibroblasts). We show here
that elements within the proximal sequence (nucleotides -557 to -513)
are necessary for the cell-specific expression of type X collagen by
hypertrophic chondrocytes. These elements bind to proteins of 100 kDa
in all three cell types, and 47 kDa in non-collagen X expressing cells
. Reporter gene activity in hypertrophic chondrocyles is reduced to th
e levels seen in non-collagen X-expressing cells in the absence of the
se elements. J. Cell. Biochem. 70:507-516, 1998. (C) 1998 Wiley-Liss,
Inc.