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.
Hirose
Satoshi
S
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
Nishizumi
Hirofumi
H
Sakano
Hitoshi
H
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