Molecular characterization of a novel transcription factor that controls stromelysin expression.
Stromelysins, which are the metalloproteinases with the widest substrate specificities, play a critical role in tumor invasion and metastasis. We have previously reported an element (SPRE) of the stromelysin promoter located between nucleotides -1221 and -1203 that is necessary and sufficient for the control of stromelysin gene expression by mitogenic activation, which induces a nuclear activity that binds to this sequence. Using a concatenated probe with several copies of this element to screen a lambda gt11 cDNA expression library from mouse Swiss 3T3 fibroblasts, we report here the molecular cloning of a cDNA coding for a novel protein (SPBP) of 937 amino acids that binds to this element and has several features of a transcription factor, such as a putative leucine zipper region, a nuclear localization signal, and a basic domain with homology to the DNA-binding domains of Fos and Jun. Evidence that SPBP is at least a critical component of the mitogen-induced SPRE nuclear binding activity is presented here. Furthermore, the transfection of an expression plasmid for SPBP transactivates reporter chloramphenicol acetyltransferase plasmids containing either the full-length stromelysin promoter or a single copy of the SPRE cloned upstream of the herpes simplex virus thymidine kinase minimal promoter. Therefore, the results presented here identify a novel transcription factor critically involved in the control of stromelysin expression.
Sanz
L
L
Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), Spain.
Moscat
J
J
Diaz-Meco
M T
MT
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic; D019278:Matrix Metalloproteinase 3; D008666:Metalloendopeptidases / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification
D018076:DNA, Complementary; D014157:Transcription Factors; D008666:Metalloendopeptidases; D019278:Matrix Metalloproteinase 3