Pub, a novel PU.1 binding protein, regulates the transcriptional activity of PU.1.
PU.1 is a member of the Ets family of transcription factors and plays critical roles in the development of hematopoietic cells such as macrophages and B cells. To elucidate the molecular mechanism(s) underlying the regulation of PU.1 function, we screened for PU.1 interacting proteins using a yeast two-hybrid approach. As a result, a novel PU.1 binding factor, which we termed Pub, was isolated. The Pub protein has one B-box zinc finger domain, followed by a coiled-coil region and a B30.2-like domain, these features being characteristic of the tripartite motif (TRIM) family of protein. The PEST domain of PU.1 was found to interact with the N-terminal portion of Pub, a region that includes the TRIM which is considered to mediate protein-protein interactions. Northern blot and RT-PCR analyses demonstrated that Pub is predominantly expressed in hematopoietic tissues and cells where PU.1 is also expressed. Using a luciferase-based assay, we showed that Pub inhibited the transcriptional activity of PU.1. Moreover, the B-box zinc finger domain of Pub was critical for this inhibitory activity. These data suggest that Pub may be important in regulating the transcriptional activity of PU.1.
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
Satoshi
S
Hirose
Hirofumi
H
Nishizumi
Hitoshi
H
Sakano
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006367:HeLa Cells; D006410:Hematopoiesis / Q000502:physiology*; D006801:Humans; D050835:Interferon Regulatory Factors; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology*; D000070584:Tripartite Motif Proteins; D020798:Two-Hybrid System Techniques; D000099232:Proto-Oncogene Protein Spi-1; D000099218:Interferon Regulatory Factor-4
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D050835:Interferon Regulatory Factors; D047908:Intracellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000070584:Tripartite Motif Proteins; D000099232:Proto-Oncogene Protein Spi-1; D000099218:Interferon Regulatory Factor-4; C481145:TRIM14 protein, human; C490593:Trim14 protein, mouse