Human X-box-binding protein 1 is required for the transcription of a subset of human class II major histocompatibility genes and forms a heterodimer with c-fos.

AUTOR(ES)

Ono, S J

RESUMO

A complementary DNA encoding a member of the leucine-zipper class of proteins (human X-box-binding protein, hXBP-1) that binds to the 3' end of the conserved X box (X2) of the HLA-DRA major histocompatibility complex gene was recently described. Further gel-retardation analysis has demonstrated that hXBP-1 also binds to HLA-DPB X2 but not to other X2 sequences. Transient transfection of a mammalian expression vector with the hXBP-1 cDNA inserted in the antisense orientation represses the surface expression of HLA-DR and HLA-DP in Raji cells. Cotransfection of the antisense hXBP-1 vector with a HLA-DRA/chloramphenicol acetyltransferase (but not a HLA-DQB/chloramphenicol acetyltransferase) reporter plasmid decreases chloramphenicol acetyltransferase activity in Raji cells and in gamma-interferon-treated HeLa cells relative to cells cotransfected with a control antisense vector. Moreover, hXBP-1 is shown to form a stable heterodimer with the product of the c-fos protooncogene. These data suggest that the hXBP-1 c-fos heterodimer is critical for the transcription of a subset of the human class II major histocompatibility complex genes and that the regulatory mechanisms for the different class II genes are distinct.

Documentos Relacionados

• Functional complementation of major histocompatibility complex class II regulatory mutants by the purified X-box-binding protein RFX.
• Characterization of a Major Histocompatibility Complex Class II X-Box-Binding Protein Enhancing Tat-Induced Transcription Directed by the Human Immunodeficiency Virus Type 1 Long Terminal Repeat
• Transcription of a subset of human class II major histocompatibility complex genes is regulated by a nucleoprotein complex that contains c-fos or an antigenically related protein.
• Evidence for multiple major histocompatibility class II X-box binding proteins.
• Interactions between the Class II Transactivator and CREB Binding Protein Increase Transcription of Major Histocompatibility Complex Class II Genes