Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are driver mutations in acute myeloid leukemia (AML) and other cancers. We report the development of new allosteric inhibitors of mutant IDH1. Crystallographic and biochemical results demonstrated that compounds of this chemical series bind to an allosteric site and lock the enzyme in a catalytically inactive conformation, thereby enabling inhibition of different clinically relevant IDH1 mutants. Treatment of IDH1 mutant primary AML cells uniformly led to a decrease in intracellular 2-HG, abrogation of the myeloid differentiation block and induction of granulocytic differentiation at the level of leukemic blasts and more immature stem-like cells, in vitro and in vivo. Molecularly, treatment with the inhibitors led to a reversal of the DNA cytosine hypermethylation patterns caused by mutant IDH1 in AML patients’ cells. Our study provides proof-of-concept for the molecular and biological activity of novel allosteric inhibitors for targeting different mutant forms of IDH1 in leukemia.

Inhibitors of apoptosis proteins (IAPs) are a conserved family of proteins identified in species ranging from virus, yeasts, nematodes, fishes, flies and mammals. The common structural feature is the presence of at least one Baculovirus IAP Repeat (BIR) domain. Hence, IAPs are also known as BIR-containing proteins (BIRCs). Most of them display anti-apoptotic properties when overexpressed. In drosophila, IAPs are sufficient and necessary to promote cell survival through a direct regulation of apoptotic proteases called caspases. In mammals, BIRC4/XIAP, the most studied IAP member can directly inhibit the activity of caspase-3, 7 and 9. However, this activity is not conserved in other IAPs and physiological relevancies of such anti-caspase activities are still discussed. A detailed analysis of IAP-deficient mice or derived cells, deletion experiments performed in drosophila and zebrafish, or research of protein partners have revealed the importance of IAPs in adaptive response to cellular stress, in cell proliferation, differentiation, signaling, motility and in immune response. This review discusses recent data that help understanding of cellular functions of IAPs.

DNA methylation (DNAm) plays a determining role in neural cell fate and provides a molecular link between early-life stress and neuropsychiatric disease. Preterm birth is a profound environmental stressor that is closely associated with alterations in connectivity of neural systems and long-term neuropsychiatric impairment. The aims of this study were to examine the relationship between preterm birth and DNAm, and to investigate factors that contribute to variance in DNAm. DNA was collected from preterm infants (birth<33 weeks gestation) and healthy controls (birth>37 weeks), and a genome-wide analysis of DNAm was performed; diffusion magnetic resonance imaging (dMRI) data were acquired from the preterm group. The major fasciculi were segmented, and fractional anisotropy, mean diffusivity and tract shape were calculated. Principal components (PC) analysis was used to investigate the contribution of MRI features and clinical variables to variance in DNAm. Differential methylation was found within 25 gene bodies and 58 promoters of protein-coding genes in preterm infants compared with controls; 10 of these have neural functions. Differences detected in the array were validated with pyrosequencing. Ninety-five percent of the variance in DNAm in preterm infants was explained by 23 PCs; corticospinal tract shape associated with 6th PC, and gender and early nutritional exposure associated with the 7th PC. Preterm birth is associated with alterations in the methylome at sites that influence neural development and function. Differential methylation analysis has identified several promising candidate genes for understanding the genetic/epigenetic basis of preterm brain injury.

The inhibitor of apoptosis protein cIAP1 (cellular inhibitor of apoptosis protein-1) is a potent regulator of the tumor necrosis factor (TNF) receptor family and NF-B signaling pathways in the cytoplasm. However, in some primary cells and tumor cell lines, cIAP1 is expressed in the nucleus, and its nuclear function remains poorly understood. Here, we show that the N-terminal part of cIAP1 directly interacts with the DNA binding domain of the E2F1 transcription factor. cIAP1 dramatically increases the transcriptional activity of E2F1 on synthetic and CCNE promoters. This function is not conserved for cIAP2 and XIAP, which are cytoplasmic proteins. Chromatin immunoprecipitation experiments demonstrate that cIAP1 is recruited on E2F binding sites of the CCNE and CCNA promoters in a cell cycle-and differentiation-dependent manner. cIAP1 silencing inhibits E2F1 DNA binding and E2F1-mediated transcriptional activation of the CCNE gene. In cells that express a nuclear cIAP1 such as HeLa, THP1 cells and primary human mammary epithelial cells, down-regulation of cIAP1 inhibits cyclin E and A expression and cell proliferation. We conclude that one of the functions of cIAP1 when localized in the nucleus is to regulate E2F1 transcriptional activity.Cellular inhibitor of apoptosis protein-1 (cIAP1, 3 also named BIRC2, HIAP2) belongs to the IAP family of proteins that all contain at least one copy of the conserved BIR (baculoviral IAP repeat) domain (1, 2). cIAP1 also contains a central CARD (caspase-activating recruitment domain) and a C-terminal RING (really interesting new gene) domain, the latter conferring to the protein an E3 ubiquitin ligase activity. cIAP1 is an important regulator of the signaling pathways activated by the tumor necrosis factor (TNF) receptor superfamily members and modulates nuclear factor-B (NF-B) activation (3-6). cIAP1 has the capacity to bind and ubiquitylate several signaling intermediates involved in these pathways, including TRAF2 (TNF receptor-associated factor 2) (1, 5-8), NIK (NF-B-inducing kinase) (9), ASK1 (apoptosis signal-regulating kinase 1) (10), NEMO (NF-B essential modulator) (11), and RIP1 (12, 13).A range of evidence suggests that cIAP1 plays a role in mammalian cancers. cIAP1-encoding Birc2 is a target gene within a chromosome 11q21 amplicon found in cervical, oral, head and neck, lung, esophageal, and hepato-cellular carcinomas (14 -18). Independently of the presence of this amplicon, cIAP1 is highly expressed in cancer samples from several origins (18 -22). The oncogenic properties of cIAP1 have been demonstrated in p53 Ϫ/Ϫ , c-Myc-expressing mouse hepatocarcinoma cells (18), in p53 ϩ/Ϫ mouse osteosarcoma (23), and in p53 Ϫ/Ϫ mouse mammary carcinoma (24). We (6, 25, 26) and others (27-29) have shown that cIAP1 was expressed mainly in the nucleus of undifferentiated, proliferating cells and was excluded upon cell differentiation (25) or apoptosis induction (27). cIAP1 is also detected in the nucleus of primary human tumor cells (15,16,28,30). In head and neck squamous cell carc...