This Article Full Text Full Text (PDF) Supplemental material Other Versions of this Article: MCB.00487-06v1 26/22/8623    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sripathy, S. P. Articles by Schultz, D. C. Search for Related Content PubMed PubMed Citation Articles by Sripathy, S. P. Articles by Schultz, D. C.

The KAP1 Corepressor Functions To Coordinate the Assembly of De Novo HP1-Demarcated Microenvironments of Heterochromatin Required for KRAB Zinc Finger Protein-Mediated Transcriptional Repression ^,

Case Western Reserve University, Department of Pharmacology and Case Comprehensive Cancer Center, 10900 Euclid Avenue, Cleveland, Ohio 44106-4965

Received 20 March 2006/ Returned for modification 1 May 2006/ Accepted 27 August 2006

KAP1/TIF1ß is proposed to be a universal corepressor protein for the KRAB zinc finger protein (KRAB-zfp) superfamily of transcriptional repressors. To characterize the role of KAP1 and KAP1-interacting proteins in transcriptional repression, we investigated the regulation of stably integrated reporter transgenes by hormone-responsive KRAB and KAP1 repressor proteins. Here, we demonstrate that depletion of endogenous KAP1 levels by small interfering RNA (siRNA) significantly inhibited KRAB-mediated transcriptional repression of a chromatin template. Similarly, reduction in cellular levels of HP1/ß/ and SETDB1 by siRNA attenuated KRAB-KAP1 repression. We also found that direct tethering of KAP1 to DNA was sufficient to repress transcription of an integrated transgene. This activity is absolutely dependent upon the interaction of KAP1 with HP1 and on an intact PHD finger and bromodomain of KAP1, suggesting that these domains function cooperatively in transcriptional corepression. The achievement of the repressed state by wild-type KAP1 involves decreased recruitment of RNA polymerase II, reduced levels of histone H3 K9 acetylation and H3K4 methylation, an increase in histone occupancy, enrichment of trimethyl histone H3K9, H3K36, and histone H4K20, and HP1 deposition at proximal regulatory sequences of the transgene. A KAP1 protein containing a mutation of the HP1 binding domain failed to induce any change in the histone modifications associated with DNA sequences of the transgene, implying that HP1-directed nuclear compartmentalization is required for transcriptional repression by the KRAB/KAP1 repression complex. The combination of these data suggests that KAP1 functions to coordinate activities that dynamically regulate changes in histone modifications and deposition of HP1 to establish a de novo microenvironment of heterochromatin, which is required for repression of gene transcription by KRAB-zfps.

Published ahead of print on 5 September 2006.

Supplemental material for this article may be found at http://mcb.asm.org/.

This article has been cited by other articles:

• Wolf, D., Cammas, F., Losson, R., Goff, S. P. (2008). Primer Binding Site-Dependent Restriction of Murine Leukemia Virus Requires HP1 Binding by TRIM28. J. Virol. 82: 4675-4679 [Abstract] [Full Text]  
• Li, X., Lee, Y.-K., Jeng, J.-C., Yen, Y., Schultz, D. C., Shih, H.-M., Ann, D. K. (2007). Role for KAP1 Serine 824 Phosphorylation and Sumoylation/Desumoylation Switch in Regulating KAP1-mediated Transcriptional Repression. J. Biol. Chem. 282: 36177-36189 [Abstract] [Full Text]  
• Wiznerowicz, M., Jakobsson, J., Szulc, J., Liao, S., Quazzola, A., Beermann, F., Aebischer, P., Trono, D. (2007). The Kruppel-associated Box Repressor Domain Can Trigger de Novo Promoter Methylation during Mouse Early Embryogenesis. J. Biol. Chem. 282: 34535-34541 [Abstract] [Full Text]  
• Wang, C., Rauscher, F. J. III, Cress, W. D., Chen, J. (2007). Regulation of E2F1 Function by the Nuclear Corepressor KAP1. J. Biol. Chem. 282: 29902-29909 [Abstract] [Full Text]  
• Mascle, X. H., Germain-Desprez, D., Huynh, P., Estephan, P., Aubry, M. (2007). Sumoylation of the Transcriptional Intermediary Factor 1beta (TIF1beta), the Co-repressor of the KRAB Multifinger Proteins, Is Required for Its Transcriptional Activity and Is Modulated by the KRAB Domain. J. Biol. Chem. 282: 10190-10202 [Abstract] [Full Text]  
• White, D. E., Negorev, D., Peng, H., Ivanov, A. V., Maul, G. G., Rauscher, F. J. III (2006). KAP1, a Novel Substrate for PIKK Family Members, Colocalizes with Numerous Damage Response Factors at DNA Lesions. Cancer Res. 66: 11594-11599 [Abstract] [Full Text]