FIBROBLAST GROWTH-FACTOR RECEPTOR SIGNALING ACTIVATES THE HUMAN INTERSTITIAL COLLAGENASE PROMOTER VIA THE BIPARTITE ETS-AP1 ELEMENT

Interstitial collagenases participate in the remodeling of skeletal ma trix and are regulated by fibroblast growth factor (FGF). A 0.2-kb fra gment of the proximal human interstitial collagenase [matrix metallopr oteinase (MMP1)] promoter conveys 4- to 8-fold induction of a lucifera se reporter in response to FGF2 in MC3T3-E1 osteoblasts. By 5'-deletio n, this response maps to nucleotides -100 to -50 relative to the trans cription initiation site. The 63- bp MMP1 promoter fragment -123 to -6 1 confers this FGF2 response on the rous sarcoma virus minimal promote r. Intact Ets and AP1 cognates in this element are both required for r esponsiveness. The AP1 site supports basal and FGF-inducible promoter activity. The intact Ets cognate represses basal transcriptional activ ity in both heterologous and native promoter contexts and is also requ ired for FGF activation. FGF2 up-regulates a DNA-binding activity that recognizes the MMP1 AP1 cognate and contains immunoreactive Fra1 and c-Jun. Both constitutive and FGF-inducible DNA-binding activities are present in MC3T3-E1 cells that recognize the MMP1 Ets cognate; prototy pic Ets transcriptional activators are not present in these complexes. Inhibitors of protein kinase C, phosphatidyl inositol 3-OH kinase, an d calmodulin-dependent protein kinase do not attenuate MMP1 promoter a ctivation. FGF2 activates ERK1/ERK2 signaling in osteoblasts; however, 25 mu M MAPK-ERK kinase (MEK) inhibitor PD98059 (inhibits by > 85% th e phosphorylation of ERK1/ERK2) has no effect on MMP1 promoter activat ion by FGF2. Ligand-activated and constitutively active FGF receptors initiate MMP1 induction. Dominant negative Ras abrogates MMP1 inductio n by constitutively active FGFR2-ROS, but dominant negative Rho and Ra c do not inhibit induction. The mitogen-activated protein kinase (MARK ) phosphatase MKP2 [inactivates extracellular regulated kinase (ERK) = Jun N-terminal kinase (JNK) > p38 MAPK] completely abrogates MMP1 act ivation, whereas PAC1 (inactivates ERK = p38 > JNK) attenuates but doe s not completely prevent induction. Thus, a Ras- and MKP2-regulated MA RK pathway, independent of ERK1/ERK2 MAPK activity, mediates FGF2 tran scriptional activation of MMP1 in MC3T3-E1 osteoblasts, converging upo n the bipartite Ets-AP1 element. The DNA-protein interactions and sign al cascades mediating FGF induction of the MMP1 promoter are distinct from two other recently described FGF response elements: the MMP1 prom oter (-123 to -61) represents a third FGF-activated transcriptional un it.