The C-terminal binding protein (CtBP) is a NADH-dependent transcriptional repressor that links carbohydrate metabolism to epigenetic regulation by recruiting diverse histone modifying complexes to chromatin. Here, global profiling of CtBP in breast cancer cells reveals that it drives epithelial to mesenchymal transition, stem cell pathways, and genome instability. CtBP expression induces mesenchymal and stem cell-like features while CtBP depletion or caloric restriction reverses gene repression and increases DNA repair. Multiple members of the CtBP-targeted gene network are selectively down-regulated in aggressive breast cancer subtypes. Differential expression of CtBP-targeted genes predicts poor clinical outcome in breast cancer patients, and elevated levels of CtBP in patient tumors predict shorter median survival. Finally, both CtBP promoter targeting and gene repression can be reversed by small molecule inhibition. These findings define broad roles for CtBP in breast cancer biology and suggest novel chromatin-based strategies for pharmacologic and metabolic intervention in cancer.

Studies in Saccharomyces cerevisiae indicate the histone variant H2A.Z is deposited at promoters by the chromatin remodeling protein Swr1 and plays a critical role in the regulation of transcription. In higher eukaryotes, however, little is known about the distribution, method of deposition, and function of H2A.Z at promoters. Using biochemical studies, we demonstrated previously that SRCAP (SNF-2-related CREB-binding protein activator protein), the human ortholog of Swr1, could catalyze deposition of H2A.Z into nucleosomes. To address whether SRCAP directs H2A.Z deposition in vivo, promoters targeted by SRCAP were identified by a chromatin immunoprecipitation (ChIP)-on-chip assay. ChIP assays on a subset of these promoters confirmed the presence of SRCAP on inactive and active promoters. The highest levels of SRCAP were observed on the active SP-1, G3BP, and FAD synthetase promoters. Detailed analyses of these promoters indicate sites of SRCAP binding overlap or occur adjacent to the sites of H2A.Z deposition. Knockdown of SRCAP levels using siRNA resulted in loss of SRCAP at these promoters, decreased deposition of H2A.Z and acetylated H2A.Z, and a decrease in levels of SP-1, G3BP, and FAD synthetase mRNA. Thus, these studies provide the first evidence that SRCAP is recruited to promoters and is critical for the deposition of H2A.Z.Chromatin remodeling has emerged as a key mechanism for gene regulation in development and cancer. The histone variant H2A.Z is a universally conserved intrinsic component of eukaryotic chromatin (1). Studies in Saccharomyces cerevisiae indicate that H2A.Z is required for normal gene expression, is distributed throughout the genome, and appears to be required for proper recruitment of RNA polymerase II (RNAP II) 2 and TATA-binding protein (TBP) (2). The highest levels of H2A.Z in S. cerevisiae occur within nucleosomes located at inactive promoters where it has been postulated to provide the correct promoter architecture to facilitate activation of transcription (3-5). Activation of transcription results in decreased levels of H2A.Z and an increase in acetylated H2A.Z, which has been proposed to facilitate disassembly/reassembly of nucleosomes (6 -8).In higher eukaryotes, the genomic distribution and the biological function(s) of H2A.Z are poorly defined. In mammals, H2A.Z is essential for embryonic development and chromosome segregation, and increased H2A.Z expression is implicated in cardiac hypertrophy (9 -11). Studies done in chicken cells suggest that deposition of both H2A.Z and acetylated H2A.Z in higher eukaryotes differs from that observed in S. cerevisiae and occurs at active promoters but not at inactive promoters (12, 13). The specific role that H2A.Z plays at active promoters in higher eukaryotes has not been established.The exchange of H2A.Z into nucleosomes in S. cerevisiae has been demonstrated by genetic and biochemical approaches to be carried out by the catalytic subunit of the SWR-C complex, termed Swr1 (14, 15). A SRCAP complex, which is the human ortholog of the...

Insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) is an oncofetal protein expressed in various cancers including leukemia. In this study, we assessed the role of IGF2BP1 in orchestrating leukemia stem cell properties. Tumor-initiating potential, sensitivity to chemotherapeutic agents and expression of cancer stem cell markers were assessed in a panel of myeloid, B-, and T-cell leukemia cell lines using gain-and loss-of-function systems, cross-linking immunoprecipitation (CLIP), and photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) techniques. Here we report that genetic or chemical inhibition of IGF2BP1 decreases leukemia cells' tumorigenicity, promotes myeloid differentiation, increases leukemia cell death, and sensitizes leukemia cells to chemotherapeutic drugs. IGF2BP1 affects proliferation and tumorigenic potential of leukemia cells through critical regulators of self-renewal HOXB4 and MYB and through regulation of expression of the aldehyde dehydrogenase, Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Cell therapy with autologous donor-specific regulatory T cells (Tregs) is a promising strategy to minimize immunosuppression in transplant recipients. Chimeric antigen receptor (CAR) technology has recently been used successfully to generate donor-specific Tregs and overcome the limitations of enrichment protocols based on repetitive stimulations with alloantigens. However, the ability of CAR-Treg therapy to control alloreactivity in immunocompetent recipients is unknown. We first analyzed the effect of donor-specific CAR Tregs on alloreactivity in naive, immunocompetent mice receiving skin allografts. Tregs expressing an irrelevant or anti-HLA-A2-specific CAR were administered to Bl/6 mice at the time of transplanting an HLA-A2 + Bl/6 skin graft.Donor-specific CAR-Tregs, but not irrelevant-CAR Tregs, significantly delayed skin rejection and diminished donor-specific antibodies (DSAs) and frequencies of DSAsecreting B cells. Donor-specific CAR-Treg-treated mice also had a weaker recall DSA response, but normal responses to an irrelevant antigen, demonstrating antigen-specific suppression. When donor-specific CAR Tregs were tested in HLA-A2-sensitized mice, they were unable to delay allograft rejection or diminish DSAs. The finding that donor-specific CAR-Tregs restrain de novo but not memory alloreactivity has important implications for their use as an adoptive cell therapy in transplantation. K E Y W O R D S alloantigen, B cell biology, basic (laboratory) research/science, cellular biology, cellular transplantation (non-islet), immunosuppression/immune modulation, T cell biology, tolerance, translational research/science | 1563 SICARD et Al.