Oncogenic Calreticulin Induces Immune Escape by Stimulating TGF-β Expression and Regulatory T Cell Expansion in the Bone Marrow Microenvironment - microarray
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE241162 | GEO | 2024/05/30
REPOSITORIES: GEO
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Project description:Experimental data indicates unique activation of the unfolded response in calreticulin (CALR) mutant myeloproliferative neoplasms (MPN). To dissect UPR activation in an MPN, calreticulin-mutant context at the transcriptional level, RNA-seq was performed. Cell lines were generated with the addition of a plasmid containing the thrombopoietin receptor (MPL) in addition to a CALR variant: either wild-type calreticulin, calreticulin with a deletion of fifty-two base pairs/type I mutant, or calreticulin with an insertion of five base pairs/type II mutant. Cells were cultured in growth media containing 10% FBS RPMI with penicillin/streptomycin addition in a 5% CO2 incubator. Cells were washed three times with PBS followed by media replacement using growth media with or without IL3 addition. In unstarved conditions, cells were supplied with the cytokine IL3 at a 1:10,000 dilution for a final concentration of 2 ng/mL; in starved conditions, cells were depleted of the IL3 cytokine addition for twenty-four hours. RNA-seq was performed on both unstarved and starved cells in triplicates for each genotype. Additionally, for preliminary data purposes, a cell line was generated with MPL plasmid transduction and with the transduction of a plasmid containing the JAK2 kinase with the V617F mutation to examine MPN activation in a JAK2 mutant, MPN context; these samples (unstarved and starved) were not sequenced in triplicates but with one sample each.
2022-03-31 | GSE173805 | GEO
Project description:Somatic mutations in calreticulin (CALR) are present in approximately 40% of patients with myeloproliferative neoplasms (MPN). However, the mechanism by which mutant CALR is oncogenic is unknown. Here, we demonstrate that a megakaryocytic-specific MPN phenotype is induced when mutant CALR is over-expressed in mice and that the thrombopoietin receptor, MPL is required for mutant CALR driven transformation. Whole transcriptome analysis reveals enrichment of STAT signatures in mutant CALR transformed cells and JAK2 inhibitor treatment abrogates STAT activation. Employing extensive mutagenesis-based structure-function analysis we demonstrate that the positively charged amino acids within the mutant CALR C-terminus are required for cellular transformation through facilitating physical interaction between mutant CALR and MPL. Together, our findings elucidate a novel mechanism of cancer pathogenesis.
2016-04-14 | GSE74890 | GEO
Project description:Mutations in the endoplasmic reticulum (ER) chaperone calreticulin (CALR) are common in myeloproliferative neoplasm (MPN) patients, activate the thrombopoietin receptor (MPL), and mediate constitutive JAK/STAT signaling. The mechanisms by which CALR mutations cause myeloid transformation are incompletely defined. We employed mass spectrometry proteomics to identify novel CALR-mutant interacting proteins. Mutant CALR caused mislocalization of binding partners and increased recruitment of FLI1, ERP57 and CALR to the MPL promoter to enhance transcription. CALR 52 mutant was also found to increase genome-wide recruitment of Fli1 to the chromatin. Overall, these results show that type 1 CALR mutant modulates Fli1 cellular localization and recruitment.
2018-09-19 | GSE120134 | GEO
Project description:There is growing evidence that Ph-negative myeloproliferative neoplasms (MPNs) are blood cancers in which multiple molecular mechanisms are significantly disturbed. Since their discovery in 2016, CALR (calreticulin) type 1 and type 2 driver mutations have been demonstrated to trigger pathogenic mechanisms apart from the well-documented activation of JAK2/MPL-related pathways affecting these diseases. C. elegans seems to be a suitable model for the study of these mechanisms since they have a CALR ortholog (crt-1) but have no JAK or MPL ortholog. We used microarrays in C. elegans strains harboring patient-like calreticulin mutations to identify JAK/MPL-independent molecular mechanisms derived from mutant calreticulin and identified a significant disruption of some of the typically altered biological processes in cancer and Ph-negative MPN patients. Finally, we compared the expression of the genes participating in these processes with a calreticulin knockout strain in order to examine if the alteration of these processes is a consequence of a gain or a loss of function of the mutant protein.
2023-01-09 | GSE201599 | GEO
Project description:Somatic mutations of calreticulin (CALR) have been described in approximately 30-40% of JAK2 and MPL unmutated essential trombocytemia and primary myelofibrosis patients. CALR is a chaperone that localizes primarily in the endoplasmic reticulum (ER) where it is responsible for the control of proper protein folding and for the calcium retention. Recent data have demonstrated that the TPO receptor (MPL) is essential for the development of CALR mutant-driven myeloproliferative neoplasms (MPNs). However, the precise mechanism of action of CALR mutants haven't been fully unraveled. In this study, we attempted to clarify whether CALR mutations may affect the functions of CALR in the ER under homeostatic conditions. Our results showed that CALR mutants impair the ability to respond to the ER stress and reduce the activation of the pro-apoptotic pathway of the unfolded protein response, therefore allowing the accumulation of unfolded proteins and conferring resistance to ER-stress induced apoptosis. Moreover, our data demonstrated that CALR mutations induce increased sensitivity to oxidative stress, reducing the ability to counteract ROS intracellular accumulation and thus leading to increase oxidative DNA damage. We finally demonstrated that the downmodulation of OXR1 in CALR-mutated cells could be one of the molecular mechanisms responsible for the increased sensitivity to oxidative stress mediated by CALR mutations. Altogether, our data identify a novel MPL-independent mechanism involved in the development of MPNs mediated by CALR mutants: CALR mutations negatively impact on the capability of cells to respond to oxidative stress, and this in turn leads to increase DNA damage and genomic instability. We used microarrays to detail the change of gene expression caused by calreticulin mutations in K562 cells
2020-08-20 | GSE102900 | GEO
Project description:Somatic mutations of calreticulin (CALR) have been described in approximately 30-40% of JAK2 and MPL unmutated Essential Thrombocythemia and Primary Myelofibrosis patients. CALR is an endoplasmic reticulum (ER) chaperone responsible for proper protein folding and calcium retention. Recent data demonstrated that the TPO receptor (MPL) is essential for the development of CALR mutant-driven Myeloproliferative Neoplasms (MPNs). However, the precise mechanism of action of CALR mutants haven't been fully unraveled. In this study, we showed that CALR mutants impair the ability to respond to the ER stress and reduce the activation of the pro-apoptotic pathway of the unfolded protein response (UPR). Moreover, our data demonstrated that CALR mutations induce increased sensitivity to oxidative stress, leading to increase oxidative DNA damage. We finally demonstrated that the downmodulation of OXR1 in CALR-mutated cells could be one of the molecular mechanisms responsible for the increased sensitivity to oxidative stress mediated by mutant CALR. Altogether, our data identify novel mechanisms collaborating with MPL activation in CALR-mediated cellular transformation. CALR mutants negatively impact on the capability of cells to respond to oxidative stress leading to genomic instability and on the ability to react to ER stress, causing resistance to UPR-induced apoptosis.
2019-08-04 | GSE127250 | GEO
Project description:We established a model for myeloproliferative disease in mice, that is based on primary bone marrow expressing human Thrombopoietin receptor and human mutant Calrdel52. To learn more about cellular and transcriptional rearrangements in the bone marrow we performed single cell RNA sequencing comparing bone marrow cells of empty vector control mice with mice that received MPL-Calrdel52 bone marrow.
2024-05-30 | GSE241364 | GEO
Project description:Disease frameshift mutations of calreticulin (CALR) are the second most prevalent driver mutations in essential thrombocythemia (ET) and primary myelofibrosis (PMF). To identify potential targeted therapies for CALR mutated myeloproliferative neoplasms, we aimed to search for small molecule drugs that selectively inhibit the growth of CALR mutated cells using high-throughput drug screening. We investigated 89,172 compounds using isogenic cell lines and identified several hits targeting the ATR-CHK1 pathway. The selective inhibitory effect of these candidate compounds was validated in a co-culture assay of CALR mutated and wild type cells. Of the tested hit compounds, CHK1 inhibitors potently depleted CALR mutated cells, allowing CALR wild type cell dominance in the co-culture over time. Neither CALR deficient cells nor JAK2V617F mutated cells showed hypersensitivity to the drug treatment, suggesting that the vulnerability to ATR-CHK1 inhibition is specifically caused by the oncogenic activation by the mutant CALR. CHK1 inhibitors induced replication stress in CALR mutated cells revealed by elevated pan-nuclear staining for γH2AX and hyperphosphorylation of RPA2. They also promoted S-phase cell cycle arrest and blocked the completion of DNA replication in CALR mutated cells. Transcriptomic and phosphoproteomic analyses revealed a replication stress signature caused by the oncogenic CALR mutation, suggesting an intrinsic vulnerability of these cells to CHK1 perturbation. This study indicates that ATR-CHK1 pathway is a potential therapeutic target in CALR mutated hematopoietic cells.
2021-09-07 | PXD026803 | Pride
Project description:Cancer is driven by somatic mutations that provide a fitness advantage. While targeted therapies often focus on the mutated gene or its direct downstream effectors, imbalances brought on by cell-state alterations may also confer unique vulnerabilities. In myeloproliferative neoplasms (MPN), somatic mutations in the calreticulin (CALR) gene are disease-initiating through aberrant binding of mutant CALR to the thrombopoietin receptor MPL and ligand-independent activation of JAK-STAT signaling. Despite these mechanistic insights into the pathogenesis of CALR-mutant MPN, there are currently no mutant CALR-selective therapies available. Here, we identified differential upregulation of unfolded and ubiquitinylated proteins, the proteasome and the ER stress response in CALR-mutant hematopoietic stem cells and megakaryocyte progenitors. We further found that combined pharmacological inhibition of the proteasome and IRE1-XBP1 axis of the ER stress response preferentially targets Calr-mutated stem and progenitors over wild-type cells in vivo, resulting in an amelioration in the MPN phenotype. Together, these findings leverage loss of proteostasis in Calr-mutant MPN to identify combinatorial dependencies that may be targeted for therapeutic benefit.
2023-10-12 | GSE207684 | GEO
Project description:Microarray-data (Illumina MouseWG-6 v2) of knee cartilage of wild-type and Dio2 -/- -mice were re-analyzed to identify differential expressed genes independent of mechanical loading conditions by forced treadmill-running. Differential expression analyses of articular cartilage of Dio2-/- (N = 9) and wild-type-mice (N = 11) while applying a cutoff threshold (P < 0.05 (FDR) and FC > |1,5|) resulted in 1 probe located in Calreticulin (Calr) that was found significantly downregulated in Dio2-/- mice. The beneficial homeostatic state of articular cartilage in Dio2-/- mice is accompanied with significant lower expression of Calr. Functional analyses further showed that upregulation of Calr expression could act as an initiator of cartilage destruction.
2016-04-27 | GSE79239 | GEO