Hany Abdel-Hafiz, Mahmoud E1-Rehany 1, Jeffrey C. Dunkelberg 2
1-Department of Biochemistry, School of Medicine, El-Minia University, Egypt, 2- Department of Endocrinology, School of Medicine, UCHSC, Denver, Colorado, USA.
Garyounis Medical Journal Vol. 21, No.2. 2004:01-14
Background & objectives: ATF-2 is ubiquitously expressed in adult mouse tissues, and yet the ATF-2 knockout mouse demonstrated that ATF-2 is specifically required for normal skeletal and central nervous system development. These findings suggest that developmental stage and/or tissue-specific proteins interacting with ATF-2 could dictate cell-specific functions of ATF-2.Materials and Methods: Technique used included protein gel electrophoresis, fat western blot analyzer, electrophoresis mobility shift assay, Immunoprecipitation and protein dimerization. Results: We have identified two novel proteins, 52-Zn and 67-LZ, that interact with ATF-2 in yeast two-hybrid assay and we showed that their mRNA expression is restricted to the embryonic stage of mouse development. 52-Zn contains a putative zinc finger domain and interacts only with full-length ATF-2 in vivo. By contrast, 67-LZ contains a leucine zipper-like domain followed by a phosphatidylinositol 3-phosphate (PI3P)-binding FYVE-finger domain, is able to bind to the DNA-binding!leucine zipper domain of ATF-2 in vivo and in vitro and markedly stimulates in vitro DNA- binding by ATF-2. The ability of 67-LZ to functionally interact with ATF-2 in HeLa cell transfection assay is dependent on MEKK-l activity, suggesting that ATF-2 phosphorylation by p38 kinase and/or Jun kinase is required for in vivo interaction between ATF-2 and this protein. Conclusions: Together, these data provide important insights into how ATF-2 function may be regulated in an embryonic stage-dependent manner, and indicate that distinct ATF-2 structural domains dictate different protein-protein interactions, thus increasing the versatility of ATF-2 function.
Keywords: Leucine Zipper, ATF-2, Transcription, FYVE-finger, Protein.