Disease relevance of TRIM24

• In a cohort of 19 tamoxifen-resistant breast tumor samples, there was no significant difference in the level of the RIP140 and TIF-1 and corepressor SMRT mRNA compared with tamoxifen-treated tumors (n = 6) or untreated tumors (n = 21) [1].
• Preferential expression of the transcription coactivator HTIF1alpha gene in acute myeloid leukemia and MDS-related AML [2].
• With the assumption that this gene may be related to AML, we investigated the HTIF1alpha DNA structure and RNA expression in leukemic cells from 36 M1-M5 AML patients (28 "de novo" and eight "secondary" to myelodysplastic syndrome (MDS)) [2].

High impact information on TRIM24

• T18, similar to PML-RARalpha, disrupts the RA-dependent activity of this complex in a dominant-negative manner resulting in a growth advantage [3].
• We further show that trichostatin A, an inhibitor of histone deacetylases, can interfere with both TIF1 and HP1 silencing [4].
• The characteristics of these interactions have led us to suggest that TIF1 might be a mediator of the NR ligand-inducible activation function AF-2 [5].
• In the present study, individual members of each subfamily were tested for transcriptional repression and interaction with TIF1 beta and two other closely related family members (TIF1 alpha and TIF1 gamma) [6].
• All KRAB variants were shown, (i) to repress transcription when targeted to DNA through fusion to a heterologous DNA-binding domain in mammalian cells, and (ii) to interact specifically with TIF1 beta, but not with TIF1 alpha or TIF1 gamma [6].

Biological context of TRIM24

• We have characterized the nuclear receptor binding site on hTIF1 and shown that a region of 26 residues is sufficient for hormone-dependent binding to the estrogen receptor [7].
• As shown by point mutagenesis, the AF2 activation domain of ER is required for the binding of hTIF1 but not sufficient, since a short region encompassing the conserved amphipathic alpha-helix corresponding to this domain fails to precipitate hTIF1 [7].
• The Krüppel-associated box (KRAB) domain, originally identified as a 75-aa sequence present in numerous Krüppel-type zinc-finger proteins, is a potent DNA-binding-dependent transcriptional repression domain that is believed to function through interaction with the transcriptional intermediary factor 1 (TIF1) beta [6].
• HTIF1alpha, a transcription coactivator which is able to mediate RARalpha activity and functionally interact with PML, is encoded by a gene on chromosome 7q32-34, which is a critical region in acute myeloid leukemias (AML) [2].
• Finally, transactivation assays demonstrate that the defective transcriptional activity of the H11 mutant can be rescued by ectopic expression of TIF1 but not of TIF2 [8].

Anatomical context of TRIM24

• Using Northern analysis, we observed no significant difference between the amount of either TIF-1 or SUG-1 mRNA expressed in parental MCF-7 and MCF-7 tamoxifen-resistant cell lines [1].
• We also found that HTIF1alpha expression was high in myeloid cell lines [2].
• In K562 cells, HTIF1alpha RNA levels did not change after hemin-induced erythroid differentiation [2].
• Furthermore, TIF1delta is unique among the TIF1 family proteins in that its expression is largely restricted to the testis and confined to haploid elongating spermatids, where it associates preferentially with HP1 isotype gamma (HP1gamma) and forms discrete foci dispersed within the centromeric chromocenter and the surrounding nucleoplasm [9].
• Partially purified preparations of TIF-1 (Mr 10,000 to 16,000) inhibit the growth of all human tumor cell lines tested and stimulate the growth of normal human fibroblasts and epithelial cells in monolayer cultures [10].

Associations of TRIM24 with chemical compounds

• We also demonstrate that hTIF1 association with DNA-bound ER requires the presence of estradiol [7].
• In contrast to TIF1alpha, but like TIF1beta, TIF1 does not interact with nuclear receptors in yeast two-hybrid or GST pull-down assays and does not interfere with retinoic acid response in transfected mammalian cells [11].
• We demonstrated that the leucine-charged domain of hTIF1alpha is sufficient to interact with ERE-bound ERalpha in a ligand-dependent manner and showed that binding of ERalpha onto DNA does not significantly affect its hormone-dependent association with TIF1alpha [12].
• In myeloblastic HL60 and promyelocytic NB4 cells, induced to differentiate along the monocytic-macrophage pathway by TPA or vitamin D3, HTIF1alpha expression decreased, whereas it was maintained at high levels on induction to granulocytic differentiation by RA or DMSO [2].
• We show that members of the p160 family of co-factors and TIF-1 interact with the AF-2 domain of ERalpha [13].

Physical interactions of TRIM24

• Finally, we show that, mainly in the absence of hormone, hTIF1alpha interacts better with ERbeta than with ERalpha independently of the presence of ERE [12].

Other interactions of TRIM24

• Here we report on two novel types of RET rearrangement, PTC6 and 7, and describe the fusion products and the ret fused gene (rfg) proteins [14].
• However, the different degrees of ligand-independent interaction of the mutant ERs with the three coactivators suggest that SRC-1, TIF-1, and ERAP 140 may play different roles in receptor activity [15].
• The C-terminal region of Sp110 was homologous to the transcription intermediary factor 1 (TIF1) family of proteins [16].
• These results suggest that HTIF1alpha could play a role in myeloid differentiation, being distinctly regulated in hematopoietic lineages [2].
• The growth of human lung carcinoma A549 cells in soft agar, which was enhanced by treatment with TGF alpha from A673-conditioned media, was inhibited by treatment with TIF-1 derived from the same media [10].

Analytical, diagnostic and therapeutic context of TRIM24

• Sequence analysis reveals that this protein is the human homolog of mouse TIF1 (transcription intermediary factor 1) shown to enhance nuclear receptor ligand-dependent activation function 2 (AF2) in yeast [7].
• Although both TIF-1 and TIF-2 are obtained from the same source, they can be distinguished by their molecular weight, heat lability, elution pattern from reverse-phase high-pressure liquid chromatography, and their effect on the growth of mink lung epithelial cells [17].
• Concentrations of CP, 4OHCP, TT and T were determined using GC and HPLC [18].

References