Activity of the TonEBP/OREBP transactivation domain varies directly with extracellular NaCl concentration

• DOI: 10.1073/pnas.241637298
• Publication Date: 2002-07-26T14:36:44Z
• Authors: Joan D. Ferraris; Chester K. Williams; Prita Persaud; Zheng Zhang; Ye Chen; Maurice B. Burg
• Keywords: Transcription

Hypertonicity-induced binding of the transcription factor TonEBP/OREBP to its cognate DNA element, ORE/TonE, is associated with increased several osmotically regulated genes. Previously, it was found that hypertonicity rapidly causes nuclear translocation and phosphorylation and, more slowly, increases abundance. Also, C terminus contain a transactivation domain (TAD). We have now tested for tonicity dependence TAD activity 983 C-terminal amino acids TonEBP/OREBP. HepG2 cells were cotransfected reporter construct one expression vector constructs. The contained GAL4 elements, minimal promoter, Photinus luciferase gene. vectors generate chimeras comprised fused (i) TonEBP/OREBP, (ii) 17 glutamine residues, (iii) c-Jun, or (iv) no TAD. All TAD-containing functional at normal extracellular osmolality (300 mosmol/kg), but only chimera containing varied NaCl concentration, decreasing by >80% 200 mosmol/kg increasing 8-fold 500 mosmol/kg. constitutively localized nucleus showed tonicity-dependent posttranslational modification consistent phosphorylation. reduced herbimycin, tyrosine kinase inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole, protein CK2 inhibitor. Thus, osmotically, apparently