Transcription activating property of autoantigen SG2NA and modulating effect of WD-40 repeats.
Autoantibodies to intracellular proteins have been detected in sera of patients with various forms of cancer. Nuclear autoantigen SG2NA (S, G2 phase nuclear antigen) was isolated using autoantibodies from a patient with bladder and lung cancers and its expression is enhanced in the S and G2 phases of the cell cycle. Molecular cloning revealed that the C-terminal region of SG2NA contains six WD-40 repeats, motifs that are present in a large family of proteins with diverse functions. We show that the N-terminal region of SG2NA (aa 1-391) acted as a strong transcriptional activator in both yeast and mammalian cells. In contrast, the C-terminal WD-40 repeats had an inhibitory effect on transcription activation. We performed molecular swapping experiments by substituting the WD-40 repeats of SG2NA with those of yeast Met30 and Cdc4 and showed that the WD-40 regions from either Met30 or Cdc4 were capable of reproducing transcription repression function. The SG2NA WD-40 repeats were also able to repress basal level transcription and transactivation function of a GAL4-VP16 chimera. These observations suggest that some WD-40 repeats may have, as one of their functions, a negative regulatory role in the biological activities of their own and perhaps other proteins.
Zhu
W
W
W. M. Keck Autoimmune Disease Center, Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Chan
E K
EK
Li
J
J
Hemmerich
P
P
Tan
E M
EM
D000818:Animals; D001324:Autoantigens / Q000378:metabolism*; D015153:Blotting, Western; D019556:COS Cells; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002453:Cell Cycle; D004305:Dose-Response Relationship, Drug; D017353:Gene Deletion; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D015398:Signal Transduction; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D001749:Urinary Bladder Neoplasms / Q000378:metabolism
D001324:Autoantigens; D002148:Calmodulin-Binding Proteins; D011993:Recombinant Fusion Proteins; C405682:STRN3 protein, human