Characterization of two distinct families of transcription factors that bind to the CCAAT box region of the human COL1A2 gene

✍ Scribed by Malcolm Collins; Arlene A. Smith; M. Iqbal Parker

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 222 KB
• Volume: 70
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/(sici)1097-4644(19980915)70:4<455::aid-jcb3>3.0.co;2-i

✦ Synopsis

Both the mouse and human ␣2(I) procollagen promoters contain an inverted CCAAT box at Ϫ80, but only the human promoter contains an additional regulatory element, the collagen modulating element (CME), immediately downstream of the CCAAT box [Collins et al. (1997): Biochem J 322:199-206]. In this study, the transcription factors that bind to the G/CBE and CME within the human promoter were characterized in SVWI-38 and CT-1 nuclear extracts. Two distinct proteins bind to the CME, and both were identified as heat-labile factors that were sensitive to high ionic strengths and required Zn 2ϩ for DNA-binding activity. These proteins had Stokes radii of 4.12 and 3.15 nm, sedimentation coefficients of 3.9 and 3.2 S and native molecular weights of 66 and 41 kDa, respectively. On the basis of biochemical and DNA-binding properties, the CME binding proteins are probably novel factors involved in the regulation of the human ␣2(I) procollagen gene. By contrast, the G/CBE binding proteins were more resistant to heat, ionic strength, and divalent metal ion chelators, demonstrating that the G/CBE and CME binding proteins had distinct DNA-binding properties. The above properties suggest that this factor is a member of the previously characterized family of CCAAT box-binding factors, CBF, NF-Y, CP-1 and ␣-CP1. Taken together, these physicochemical properties of the COL1A2 CCAAT box and CME-binding proteins demonstrated that they were distinct unrelated transcription factors. These results also suggest that there is a distinct difference in the DNA-binding activity between the equivalent region of the mouse and human ␣2(I) procollagen promoters.