Project description:Inhibitors of Apoptosis Proteins (IAPs) regulate apoptosis in response to various cellular assaults. Using both genetic and pharmacological approaches we demonstrate here that the IAPs not only support opportunistic survival of intracellular human pathogens like Chlamydia pneumoniae but also controls plasticity of iNOS+ M1 macrophage during the course of infection and render them refractory for immune stimulation. Treatment of Th1 primed macrophages with birinapant (IAP specific antagonist) inhibited NO generation and relevant proteins involved in innate immune signalling. Accordingly, birinapant promoted hypoxia, angiogenesis and tumor induced M2 polarization of iNOS+ M1 macrophages. Interestingly, birinapant driven changes in immune signaling was accompanied with changes in the expression of various proteins involved in the metabolism thus revealing the new role of IAP proteins on immune metabolic reprogramming in committed macrophages.
Project description:Cellular inhibitor of apoptosis proteins 1 and 2 (c-IAP1/2) play central roles in signal transduction mediated by numerous receptors that participate in inflammatory and immune responses. In certain pathways, such as activation of NF-kB, their degradation is a major regulatory event and is physiologically induced by activation of receptors. Additionally, a number of synthetic compounds have been developed that also target the c-IAPs and induce their degradation. However, the extent of a synthetic IAP antagonist’s ability to mirror the transcriptional program by a physiological signal remains unclear. Here we take a systems approach to compare the transcriptional programs triggered by activation of CD30, a well-characterized receptor previously shown to induce the degradation of the c-IAPs, to SM-164, a synthetic IAP antagonist that specifically triggers c-IAP degradation. Employing a technique that allows the specific analysis of newly transcribed RNA, we have generated comparative transcriptome profiles for CD30 activation and SM-164 treatment. Analysis of these profiles revealed that the genes regulated by each stimulus were not completely shared, indicating novel functions of IAP antagonists and consequences of c-IAP1/2 degradation. The data identified a role for c-IAP1/2 in the regulation of the ribosome and protein synthesis, which was subsequently confirmed by biological assays. These findings expand our knowledge of the roles of c-IAP1/2 in signaling and provide insight into the mechanism of synthetic IAP antagonists, furthering our understanding of their therapeutic potential. This submission contains two different experiments. In experiment 1, cells were exposed to drug treament (DMSO or SM-164) for 3 hours. In experiment 2, cells were exposed to an adherent layer of CHO cells either expressing or not CD30L. Each treatment in each experiment was conducted once, leading to a total of 4 samples.
Project description:Cellular inhibitor of apoptosis proteins 1 and 2 (c-IAP1/2) play central roles in signal transduction mediated by numerous receptors that participate in inflammatory and immune responses. In certain pathways, such as activation of NF-kB, their degradation is a major regulatory event and is physiologically induced by activation of receptors. Additionally, a number of synthetic compounds have been developed that also target the c-IAPs and induce their degradation. However, the extent of a synthetic IAP antagonist’s ability to mirror the transcriptional program by a physiological signal remains unclear. Here we take a systems approach to compare the transcriptional programs triggered by activation of CD30, a well-characterized receptor previously shown to induce the degradation of the c-IAPs, to SM-164, a synthetic IAP antagonist that specifically triggers c-IAP degradation. Employing a technique that allows the specific analysis of newly transcribed RNA, we have generated comparative transcriptome profiles for CD30 activation and SM-164 treatment. Analysis of these profiles revealed that the genes regulated by each stimulus were not completely shared, indicating novel functions of IAP antagonists and consequences of c-IAP1/2 degradation. The data identified a role for c-IAP1/2 in the regulation of the ribosome and protein synthesis, which was subsequently confirmed by biological assays. These findings expand our knowledge of the roles of c-IAP1/2 in signaling and provide insight into the mechanism of synthetic IAP antagonists, furthering our understanding of their therapeutic potential.
Project description:Sexual commitment is a crucial step in the life cycle of the human malaria parasite that allows for the formation of transmissible gametocyte stages. The process of sexual commitment is influenced by various factors and is also marked by the timely expression of a minimal set of molecular markers at the schizont stage. Prime among them is AP2-G, a transcription factor belonging to the apitella AP2 family of TFs that drives sexual commitment. Apart from AP2-G, one uniquely expressed protein in sexually committed schizonts is MSRP1. Here, taking advantage of the two sexual commitment protein markers we established transgenic reporter parasite lines which allowed us to isolate sexually committed schizonts. We have performed whole cell proteomics and mapped the first comprehensive proteome of sexually committed schizonts in the human malaria parasite, Plasmodium falciparum. We have identified additional proteins that are relatively highly expressed in sexually committed schizonts
Project description:The proteasome is a central regulatory hub for intracellular signaling by degrading numerous signaling mediators. Immunoproteasomes are specialized types of proteasomes known to be involved in shaping adaptive immune responses, but their role for innate immune signaling is elusive. Here, we analyzed immunoproteasome function for polarization of alveolar macrophages which are highly specialized tissue macrophages of the alveolar surface of the lung. Classical activation (M1 polarization) of primary alveolar macrophages by LPS/IFNγ transcriptionally induced all three immunoproteasome subunits LMP2, LMP7, and MECL-1. In contrast, IL-4 triggered alternative (M2) activation was accompanied by posttranscriptional upregulation of LMP2 and LMP7. Accordingly, immunoproteasome activity increased in M1 cells, and to some extent under M2 conditions. Analyzing the polarization capability from LMP7 deficient mice revealed no effect on the LPS/IFNγ triggered M1 profile, but uncovered a distorted M2 profile for IL-4 stimulated LMP7-/- alveolar macrophages as characterized by increased M2 marker gene expression and CCL17 cytokine release. This shift in immunoproteasome-dependent M2 polarization was accompanied by amplified AKT/STAT6 activation and IRF4 expression in LMP7-/- alveolar macrophages. IL-13 stimulation of LMP7 deficient cells induced a similar M2 skewed profile and IL4Rα protein expression was generally elevated in LMP7-/- alveolar macrophages, indicating that amplified IL4R signaling in immunoproteasome defective cells may contribute to augmented M2 polarization. Importantly, treatment with an LMP7-specific proteasome inhibitor recapitulated the findings of genetic LMP7 inactivation. Our results thus suggest a novel role of immunoproteasome function for regulating innate immune function of macrophages by limiting IL4R expression and signaling. Expression data of M0 and M2 macrophages derived from Lmp7 k.o. and control animals
Project description:Insertions of endogenous retroviruses cause a significant fraction of mutations in inbred mice but not all strains are equally susceptible. Notably, most new Intracisternal A particle (IAP) ERV mutagenic insertions have occurred in C3H mice. We show here that strain-specific insertionally polymorphic IAPs have accumulated faster in C3H/HeJ mice relative to other strains and that IAP transcript levels are higher in C3H/HeJ embryonic stem (ES) cells compared to other ES cells. To investigate the mechanism for high IAP activity in C3H mice, we identified 61 IAP copies in C3H/HeJ ES cells enriched for H3K4me3 (a mark of active promoters) and, among those tested, all are unmethylated in C3H ES cells. Notably, 13 of the 61 are specific to C3H/HeJ and are members of the non-autonomous 1Δ1 IAP subfamily that is responsible for nearly all new insertions in C3H. One copy is full length with intact open reading frames and hence potentially capable of providing proteins in trans to other 1Δ1 elements. This potential “master copy” is present in other strains, including 129, but its 5’ long terminal repeat (LTR) is methylated in 129 ES cells. Thus, the unusual IAP activity in C3H may be due to reduced epigenetic repression coupled with the presence of a master copy.
Project description:TEAD transcription factors (TEAD1-4) are the downstream most effectors of Hippo pathway, that controls organ development and tissue homeostasis. TEAD proteins form a transcriptional complex with co-activators YAP-TAZ to transcribe genes that regulate cell proliferation/apoptosis. Since Hippo pathway dysregulation is common in cancer phenotypes, inhibiting / degrading TEAD and its subsequent transcriptional activity is an attractive therapeutic strategy. We exploited targeted protein degradation approach using IAP proteins as E3 ligases to target TEAD1 and develop a potent isoform specific degrader. In this study we describe development and functional profiling of hits from three such series of IAP recruiting degraders (IPDs). We also report a detailed toolkit using structural, biophysical and cellular approaches to study IAP recruiting degraders that target the lipid pocket of TEAD proteins. To assess degradation and isoform specificity of our most potent hit XB2 A538, we also analysed global proteomic changes in mesothelioma model cell line NCI-H2052, treated for 16 hours with TEAD IPD A538, matched IAP negative control, TEAD negative control and DMSO, reported in data deposited here.
Project description:Single domain antibodies or antibody mimetics, such as monobodies, can be engineered to degrade undruggable targets via fusion to ubiquitin E3 ligases. In this study we developed multi-targeting biodegrader intrabodies by harnessing an inhibitor of apoptosis (IAP) E3 ligase RING domain, or the IAP-binding motif from SMAC/DIABLO. When fused with monobodies targeting the necroptotic death effector MLKL, IAP-binding intrabodies simultaneously targeted MLKL and IAPs for proteasomal degradation, thereby blocking necroptosis while sensitising cells to apoptosis. The potent degradative capacity of the IAP RING was demonstrated via its fusion to distinct antibody mimetics, with those targeting RAS enabling IAP and RAS proto-oncogenes to be concurrently eliminated. Quantitative proteomics identified that the anti-cancer potential of select IAP-binding intrabodies was due to their removal of the chromatin remodelling BAF complex. Consequently, we show that cancer cells exhibited IAP and BAF co-dependencies, with IAP RING intrabodies prolonging animal survival in an orthotopic breast cancer model. This work positions IAP-binding intrabodies as a novel class of biodegraders, with their multi-targeting capacity enabling the toggling of cell death modalities and eradication of cancer-drivers.
Project description:In this study, we analyzed the DNA methylation levels of 4799 IAP LTRs in three murine cell types: AB2.2 ES cells, somatic cells and a neuroblastoma cell line Neuro2A. According to the results, half of the IAP LTR retrotransposons show constant methylation patterns between the three cell types whereas the remaining half display variable levels of methylation. About half of the variably methylated IAP LTRs tend to be hypomethylated in ES cells, and nearly all of this group are hypomethylated in Neuro2A cells. Interestingly, the observed hypomethylation in both cell types occur in a non-uniform, locus-specific manner and to various degrees of severity, with some of them being easily detectible by COBRA. Overall, this study demonstrates the feasibility of HT-TREBS to study alterations in DNA methylation at retrotransposons in a locus-specific manner in multiple cell types and further suggests the potential utility of this technique in developing epigenetic biomarkers for tracking disease progression. HT-TREBS has been used with the Ion Torrent PGM platform to analyze the DNA methylation of 4799 IAP LTRs in a locus-specific manner in 3 cell types: somatic cells (previously submitted under GEO Accession GSE49222), AB2.2 ES cells and Neuro2A cells