Drugging the lncRNA MALAT1 via LNA gapmeR ASO inhibits gene expression of proteasome subunits and triggers anti-multiple myeloma activity
Ontology highlight
ABSTRACT: The biological role and therapeutic potential of long non-coding RNAs (lncRNAs) in multiple myeloma (MM) are still to be investigated. Here, we studied the functional significance and the druggability of the oncogenic lncRNA MALAT1 in MM. Targeting MALAT1 by novel LNA-gapmeR anti-sense oligonucleotide antagonized MM cell proliferation and triggered apoptosis both in vitro and in vivo in a murine xenograft model of human MM. Of note, antagonism of MALAT1 dowmodulated the two major transcriptional activators of proteasome subunit genes, namely NRF1 and NRF2, and resulted in reduced trypsin, chymotrypsin and caspase-like proteasome activities and in accumulation of polyubiquitinated proteins. NRF1 and NRF2 decrease upon MALAT1-targeting was due to transcriptional activation of their negative regulator KEAP1, and resulted in reduced expression of anti-oxidant genes and increased ROS levels. In turn, NRF1 promoted MALAT1 expression thus establishing a positive feedback loop. Our findings demonstrate a crucial role of MALAT1 in the regulation of the proteasome machinery, and provide proof-of-concept that its targeting is a novel powerful option for the treatment of MM.
Project description:To identify Nrf1-dependent and Nrf2-dependent genes in the liver, we examined the gene expression profiles of Nrf1 Alb-CKO, Nrf2 knockout and Keap1 knockdown mouse livers by microarray analyses. Total RNAs from Nrf1dN/-::Alb-Cre, Nrf1dN/+, Nrf2-/-, Nrf2+/+, Keap1KD/- and Keap1KD/+ mouse livers were used for the microarray analyses.
Project description:Metabolic-associated steatohepatitis is a progressive fatty liver disease caused, in part, by hepatocyte stress linked to cholesterol overload. Counteracting this stress may be beneficial but there is insufficient understanding of underlying stress defenses to develop a therapeutic strategy. Here, we aimed to elucidate how stress-adaptive transcription factors, nuclear factor erythroid 2 related factor-1 (NRF1) and -2 (NRF2), counteract hepatic cholesterol overload and determine whether they function cooperatively. C57bl/6 mice were fed high fat, fructose, and cholesterol diet (HFFC). Expression profiling and phenotypic analyses were done on liver of mice with adult-onset and hepatocyte-specific deficiency of NRF1, NRF2, or both, and results compared to control. Chromatin immunoprecipitation (ChIP) sequencing was done and combined with expression profiles to identify genes that NRF1 and NRF2 interact with and regulate in vivo. Three weeks HFFC diet feeding to mice with NRF1 and NRF2 deficiency caused severe steatohepatitis and increased hepatic cholesterol storage. These outcomes did not occur in single gene-deficient mice or control. Expression profiling at a time preceding hepatic cholesterol overload and ChIP sequencing profiling revealed complementary gene regulation by NRF1 and NRF2 to promote cholesterol excretion and mitigate hazardous metabolic biproducts generated from converting cholesterol to bile acid. Consequently, combined gene deficiency, and not single-gene deficiency, increased liver oxidized protein level, decreased cholesterol in bile, and increased unconjugated bile acid in liver and bile. We discover, for the first time, that NRF1 and NRF2 work together to protect liver against damaging effects of excess cholesterol. Targeting these combined actions may prove an effective therapeutic strategy
Project description:The goal was to determine the gene expression differences between CB-5083 and Bortezomib treated multiple myeloma cell lines Inhibition of the AAA ATPase, p97, was recently shown to be a novel method for targeting the ubiquitin proteasome system (UPS) and CB-5083, a first in class inhibitor of p97, has demonstrated broad antitumor activity in a range of both hematological and solid tumor models. Here, we show that CB-5083 has robust activity against multiple myeloma (MM) cell lines and a number of in vivo MM models. Treatment with CB-5083 is associated with accumulation of ubiquitinated proteins, induction of the unfolded protein response (UPR) and apoptosis. CB-5083 decreases viability in MM cell lines and patient derived MM cells, including those with background proteasome inhibitor (PI) resistance. CB-5083 has a unique mechanism of action that combines well with PIs which is likely owing to the p97-dependent retro-translocation of the transcription factor, Nrf1, which transcribes proteasome subunit genes following exposure to a PI. In vivo studies using clinically relevant MM models demonstrate that single-agent CB-5083 inhibits tumor growth and combines well with MM standard of care agents. Our preclinical data demonstrate the efficacy of CB-5083 in several MM disease models and provide the rationale for clinical evaluation as monotherapy and in combination in MM.
Project description:To identify Nrf1-dependent and Nrf2-dependent genes in the liver, we examined the gene expression profiles of Nrf1 Alb-CKO, Nrf2 knockout and Keap1 knockdown mouse livers by microarray analyses.
Project description:The maintenance of protein homeostasis is an essential characteristic of life. Transcription factor NRF1 (NFE2L1) has been reported to be activated by proteasome dysfunction, although the genome-wide target genes are poorly understood. Using ChIP-seq analysis, we found a potential association between NRF1 and autophagy. Our findings highlight the new activation mechanism of autophagy through gene regulation under proteasome dysfunction.
Project description:Eukaryotic cells maintain protein homeostasis through the activity of multiple basal and inducible systems, which function in concert to allow cells to adapt to a wide range of environmental conditions. Although the transcriptional programs regulating individual pathways have been studied in detail, it is not known how the different pathways are transcriptionally integrated such that a deficiency in one pathway can be compensated by a change in an auxiliary response. One such pathway that plays an essential role in many proteostasis responses is the ubiquitin-proteasome system, which functions to degrade damaged, unfolded, or short half-life proteins. Transcriptional regulation of the proteasome is mediated by the transcription factor Nrf1. Using a conditional knockout mouse model, we found that Nrf1 regulates protein homeostasis in the endoplasmic reticulum (ER) through transcriptional regulation of the ER stress sensor ATF6. In Nrf1 conditional-knockout mice, a reduction in proteasome activity is accompanied by an ATF6-dependent downregulation of the endoplasmic reticulum-associated degradation machinery, which reduces the substrate burden on the proteasome. This indicates that Nrf1 regulates a homeostatic shift through which proteostasis in the endoplasmic reticulum and cytoplasm are coregulated based on a cell's ability to degrade proteins.
Project description:Eukaryotic cells maintain protein homeostasis through the activity of multiple basal and inducible systems, which function in concert to allow cells to adapt to a wide range of environmental conditions. Although the transcriptional programs regulating individual pathways have been studied in detail, it is not known how the different pathways are transcriptionally integrated such that a deficiency in one pathway can be compensated by a change in an auxiliary response. One such pathway that plays an essential role in many proteostasis responses is the ubiquitin-proteasome system, which functions to degrade damaged, unfolded, or short half-life proteins. Transcriptional regulation of the proteasome is mediated by the transcription factor Nrf1. Using a conditional knockout mouse model, we found that Nrf1 regulates protein homeostasis in the endoplasmic reticulum (ER) through transcriptional regulation of the ER stress sensor ATF6. In Nrf1 conditional-knockout mice, a reduction in proteasome activity is accompanied by an ATF6-dependent downregulation of the endoplasmic reticulum-associated degradation machinery, which reduces the substrate burden on the proteasome. This indicates that Nrf1 regulates a homeostatic shift through which proteostasis in the endoplasmic reticulum and cytoplasm are coregulated based on a cell's ability to degrade proteins.
Project description:We found these ROS generation is regulated by lncRNA MALAT1 and genetic ablation of MALAT1 drastically reduced ROS level and oxidative stress in mouse islet cells with the benefits of improved insulin responses in MALAT1-/- mouse. The pancreatic islet consists of five cell types (α, β and γ/PP, δ and ε cells) and very little is known about the xenobiotic detoxification pathways in these cells and their sensitivity to toxicants. We utilized single-cell RNA sequencing to analyze the role of MALAT1 in regulating oxidative stress response and insulin secretion function in distinct pancreatic cell population. We also treat the isolated pancreatic islets with 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (10 nM, 12h) to investigate the xenobiotic detoxification pathways regulation in both MALAT1 KO and WT pancreatic islets. Our result showed that a subset of genes in T2DM related pathways were significantly regulated in MALAT1 -/- β cells, with significantly unregulated INS1, INS2, and PDX1. Nrf2/detoxification pathway was also significantly activated in MALAT1 -/- β cells. In addition, MALAT1 expression level was elevated in the T2DM patients pancreatic islets cells. This study provides insights for mechanisms of regulation of oxidative stress by MALAT1-Nrf2 interaction which has the potential as a therapeutic target for the treatment of T2DM.
Project description:DNA-damage inducible 1 homolog 2 (DDI2) is an aspartic protease that cleaves and activates the transcription factor NRF1. Cellular models have shown that this pathway contributes to cell-stress adaption, for example, upon proteasome inhibition. However, DDI2 physiological function is unknown. Ddi2 Knock-out (KO) mice are embryonic lethal. However, we found that liver-specific Ddi2-KO animals are viable. We used comprehensive genetic analysis to identify the molecular pathways regulated by DDI2. We show that DDI2 mediates metallothionein (MT) expression in mouse and human hepatocytes in response to cadmium (Cd). Cd exposure inhibits the proteasome activity, resulting in NRF1 accumulation in the cytoplasm, followed by cleavage by DDI2 and translocation to the nucleus to activate MTs. Depleting DDI2 or NRF1 by CRISPR/Cas9 impaired MTs activation and sensitized the cells to Cd or cisplatin toxicity. This study identifies a new function for DDI2 that links proteasome homeostasis to heavy metal mediated toxicity.