Wild-type PML and at least four other novel proteins are localized within discrete nuclear structures known as PODs. We demonstrate here that during adenovirus infection, immediate early viral proteins from the E1 and E4 transcription units associate with the POD, which in turn undergoes a dramatic morphological change. During this process, the auto-antigen Sp-100 and NDP55 but not PML, relocate from the POD to the viral inclusion bodies, the sites of adenovirus DNA replication and late RNA transcription. The E4-ORF3 11-kD protein alone will induce this reorganization and reciprocally, viruses carrying mutations in the E4-domain fail to do so. These same viral mutants are defective in viral replication as well as the accumulation of late viral mRNAs and host cell transcription shutoff. We show that interferon (INF) treatment enhances the expression of PML, reduces or blocks PODs reorganization, and inhibits BrdU incorporation into viral inclusion bodies. In addition, cell lines engineered to overexpress PML prevent PODs from viral-induced reorganization and block or severely delay adenovirns replication. These results suggest that viral replication relies on components of the POD and that the structure is a target of early viral proteins.

During the early phase of the retroviral life cycle, only a fraction of internalized virions end up integrating their genome into the chromosome, even though the resulting proviruses are almost systematically expressed. Here, we reveal that incoming retroviral preintegration complexes trigger the exportin-mediated cytoplasmic export of the SWI/SNF component INI1 and of the nuclear body constituent PML. We further show that the HIV genome associates with these proteins before nuclear migration. In the presence of arsenic, PML is sequestered in the nucleus, and the efficiency of HIV-mediated transduction is markedly increased. These results unveil a so far unsuspected cellular response that interferes with the early steps of HIV replication.

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy, caused by mutations in the autoimmune regulator (AIRE) gene, is an autosomal recessive autoimmune disease characterized by the breakdown of tolerance to organ-specific antigens. The 545 amino acid protein encoded by AIRE contains several structural motifs suggestive of a transcriptional regulator and bears similarity to cellular proteins involved in transcriptional control. We show here that AIRE fused to a heterologous DNA binding domain activates transcription from a reporter promoter, and the activation seen requires the full-length protein or more than one activation domain. At the structural level AIRE forms homodimers through the NH 2 -terminal domain, and molecular modeling for this domain suggests a four-helix bundle structure. In agreement, we show that the common transcriptional coactivator CREB-binding protein (CBP) interacts with AIRE in vitro and in yeast nuclei through the CH1 and CH3 conserved domains. We suggest that the transcriptional transactivation properties of AIRE together with its interaction with CBP might be important in its function as disease-causing mutations almost totally abolish the activation effect.

Disaggregation of the spherical nuclear bodies termed promyelocytic (PML) oncogenic domains (PODs) is a characteristic of acute promyelocytic leukemia. Here, we demonstrate that the cAMP enhancer binding protein (CREB)-binding protein (CBP) associates with PML in vitro and is recruited to the PODs in vivo. Through its association with CBP, wild-type PML dramatically stimulates nuclear receptor transcriptional activity. These results demonstrate that a fraction of CBP is compartmentalized to the POD through its association with PML and thus suggest that PML and other POD-associated proteins may play an unexpectedly broad role in aspects of transcriptional regulation and human disease.Research on nuclear compartments has uncovered evidence for transcription-related proteins in nuclear substructures and suggests potential relevance to transcriptional regulation (1, 2). The cell nucleus contains a variety of morphologically distinct substructures called nuclear bodies, which include the sphere organelles, coiled bodies (3-5), and the promyelocytic (PML) oncogenic domains (PODs) (for review, see ref.2). The PODs (also known as nuclear domain 10 or Kr bodies) are macromolecular multiprotein complexes that are present in all cultured cell lines and are also present in vivo. A major component of the POD is the PML protein, which originally was identified as the fusion partner of the retinoic acid receptor ␣ (RAR␣) in the chromosomal translocation t(15;17), resulting in the PML-RAR␣ fusion product (6-11). PML and PML-RAR␣ proteins have been shown to modulate the activity of a set of downstream target genes, although it is not clear whether this is a direct or indirect effect on transcription (1, 12, 13). In leukemic cells from patients with acute promyelocytic leukemia who carry the translocation t(15;17), the expression of the PML-RAR␣ fusion protein disrupts the integrity of the POD. The POD structure is reformed after treatment with all-trans retinoic acid (14-16). The integrity of the compartment also is altered during adenovirus infection, when it appears that POD-associated proteins are released to viral replication domains (17). More recently, the POD has been shown to be a target of herpes, papillomavirus, and other viral proteins (for review, see refs. 2 and 18). Finally, the spinocerebellar ataxia 1 neurodegenerative disorderassociated protein (SCA1) also has been shown to colocalize with PML and to alter POD morphology (19,20).The cAMP enhancer binding protein (CREB)-binding protein (CBP) (21) functions as a transcriptional coactivator for a variety of transcription factors, including jun, fos, nuclear receptors (NRs), NF-kB, and the STAT proteins (22)(23)(24)(25)(26). The N-terminal region of CBP includes domains for association with the glucocorticoid receptor (GR) and the retinoid X receptor (RXR) (CBP amino acids 1-170), with CREB, cJun, Myb, and Sap-1a and with the HTLV-1 Tax viral protein (CBP amino acids 451-662). In addition, CBP interacts with the tumor suppressor p53 as a coregulatory factor ...