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Chimeric oncoproteins resulting from fusion of MLL to a wide variety of partnering proteins cause biologically distinctive and clinically aggressive acute leukemias. However,the mechanism of MLL-mediated leukemic transformation is not fully understood. Dot1,the only known histone H3 lysine 79 (H3K79) methyltransferase,has been shown to interact with multiple MLL fusion partners including AF9,ENL,AF10,and AF17. In this study,we utilize a conditional Dot1l deletion model to investigate the role of Dot1 in hematopoietic progenitor cell immortalization by MLL fusion proteins. Western blot and mass spectrometry show that Dot1-deficient cells are depleted of the global H3K79 methylation mark. We find that loss of Dot1 activity attenuates cell viability and colony formation potential of cells immortalized by MLL oncoproteins but not by the leukemic oncoprotein E2a-Pbx1. Although this effect is most pronounced for MLL-AF9,we find that Dot1 contributes to the viability of cells immortalized by other MLL oncoproteins that are not known to directly recruit Dot1. Cells immortalized by MLL fusions also show increased apoptosis,suggesting the involvement of Dot1 in survival pathways. In summary,our data point to a pivotal requirement for Dot1 in MLL fusion protein-mediated leukemogenesis and implicate Dot1 as a potential therapeutic target. View Publication

The platelet glycoprotein Ib-IX-V complex (GPIb-IX-IV) is the receptor for VWF and is responsible for VWF-mediated platelet activation and aggregation. Loss of the GPIb-IX-V complex is pathogenic for Bernard-soulier Syndrome (BSS),which is characterized by macrothrombocytopenia and impaired platelet function. It remains unclear how the GPIb-IX-V complex is assembled and whether there is a role for a specific molecular chaperone in the process. In the present study,we report that the assembly of the GPIb-IX-V complex depends critically on a molecular chaperone in the endoplasmic reticulum (ER): gp96 (also known as grp94 and HSP90b1). gp96/grp94 deletion in the murine hematopoietic system results in thrombocytopenia,prolonged bleeding time,and giant platelets that are clinically indistinguishable from human BSS. Loss of gp96/grp94 in vivo and in vitro leads to the concomitant reduction in GPIb-IX complex expression due to ER-associated degradation. We further demonstrate that gp96/grp94 binds selectively to the GPIX subunit,but not to gpIbα or gpIbβ. Therefore,we identify the platelet GPIX subunit of the GPIb-IX-V complex as an obligate and novel client of gp96/grp94. View Publication

Diabetic keratopathy (DK),a significant complication of diabetes,often leads to corneal damage and vision impairment. Effective models are essential for studying DK pathogenesis and evaluating potential therapeutic interventions. This study developed a novel biomimetic full-thickness corneal model for the first time,incorporating corneal epithelial cells,stromal cells,endothelial cells,and nerves to simulate DK conditions in vitro. By exposing the model to a high-glucose (HG) environment,the pathological characteristics of DK,including nerve bundle disintegration,compromised barrier integrity,increased inflammation,and oxidative stress,were successfully replicated. Transcriptomic analysis revealed that HG downregulated genes associated with axon and synapse formation while upregulating immune response and oxidative stress pathways,with C-C Motif Chemokine Ligand 5 (CCL5) identified as a key hub gene in DK pathogenesis. The therapeutic effects of Lycium barbarum glycopeptide (LBGP) were evaluated using this model and validated in db/db diabetic mice. LBGP promoted nerve regeneration,alleviated inflammation and oxidative stress in both in vitro and in vivo models. Notably,LBGP suppressed the expression of CCL5,highlighting its potential mechanism of action. This study establishes a robust biomimetic platform for investigating DK and other corneal diseases,and identifies LBGP as a promising therapeutic candidate for DK. These findings provide valuable insights into corneal disease mechanisms and pave the way for future translational research and clinical applications. Graphical abstractImage 1 Highlights•A full-thickness biomimetic corneal model containing corneal epithelium,nerves,stroma,and endothelium was constructed.•Using this model,the pathological characteristics of diabetic keratopathy were successfully replicated in vitro.•Lycium barbarum glycopeptide (LBGP) alleviated high-glucose-induced damage in vitro and in vivo models.•CCL5 plays an important role in the pathogenesis of diabetic keratopathy. View Publication

AbstractBackgroundChimeric antigen receptor (CAR) T-cell therapy depends on T cells that are genetically modified to recognize and attack cancer cells. Their effectiveness thus hinges on the functionality of a patient’s own T cells. Since CAR T-cell therapy is currently only approved for advanced cancers after at least one line of chemotherapy,we evaluated the potential negative effects of prior exposure to chemotherapy on T-cell functionality.MethodsWe studied T cells of two B-cell non-Hodgkin’s lymphoma patient cohorts,one collected before treatment (pre-therapy) and the other after one or more (median 3) lines of chemotherapy (post-therapy). Leveraging advanced multiparameter flow cytometry,single-cell RNA sequencing (scRNA-seq),whole-genome DNA methylation arrays and in vitro functionality testing of generated CAR T cells,we compared patient samples in their suitability for effective CAR T-cell therapy.ResultsWe discovered significant modifications in T-cell subsets and their transcriptional profiles secondary to chemotherapy exposure. Our analysis revealed a discernible shift towards phenotypically more differentiated T cells and an upregulation of markers indicative of T-cell exhaustion. Additionally,scRNA-seq and DNA methylation analyses revealed gene expression and epigenetic changes associated with diminished functionality in post-therapy T cells. Cytotoxicity assays demonstrated superior killing efficacy of CAR T cells derived from treatment-naïve patients compared with those with chemotherapy history.ConclusionsThese findings corroborate that employing T cells collected prior to frontline chemotherapy could enhance the effectiveness of CAR T-cell therapy and improve patient outcomes. View Publication

Tumor complexity and intratumor heterogeneity contribute to subclonal diversity. Despite advances in next-generation sequencing (NGS) and bioinformatics,detecting rare mutations in primary tumors and metastases contributing to subclonal diversity is a challenge for precision genomics. Here,in order to identify rare mutations,we adapted a recently described epithelial reprograming assay for short-term propagation of epithelial cells from primary and metastatic tumors. Using this approach,we expanded minor clones and obtained epithelial cell-specific DNA/RNA for quantitative NGS analysis. Comparative Ampliseq Comprehensive Cancer Panel sequence analyses were performed on DNA from unprocessed breast tumor and tumor cells propagated from the same tumor. We identified previously uncharacterized mutations present only in the cultured tumor cells,a subset of which has been reported in brain metastatic but not primary breast tumors. In addition,whole-genome sequencing identified mutations enriched in liver metastases of various cancers,including Notch pathway mutations/chromosomal inversions in 5/5 liver metastases,irrespective of cancer types. Mutations/rearrangements in FHIT,involved in purine metabolism,were detected in 4/5 liver metastases,and the same four liver metastases shared mutations in 32 genes,including mutations of different HLA-DR family members affecting OX40 signaling pathway,which could impact the immune response to metastatic cells. Pathway analyses of all mutated genes in liver metastases showed aberrant tumor necrosis factor and transforming growth factor signaling in metastatic cells. Epigenetic regulators including KMT2C/MLL3 and ARID1B,which are mutated in {\textgreater}50{\%} of hepatocellular carcinomas,were also mutated in liver metastases. Thus,irrespective of cancer types,organ-specific metastases may share common genomic aberrations. Since recent studies show independent evolution of primary tumors and metastases and in most cases mutation burden is higher in metastases than primary tumors,the method described here may allow early detection of subclonal somatic alterations associated with metastatic progression and potentially identify therapeutically actionable,metastasis-specific genomic aberrations. View Publication

Chagas disease,caused by the parasite Trypanosoma cruzi,affects millions of people globally. Unfortunately,the available treatment options,especially for the chronic stage of the disease,are suboptimal. Given the chronic nature of the disease and the elusive nature of the parasite,there is a high need for new and safer drugs that deliver sterile cure. Posaconazole was a promising lead in the drug discovery pipeline but ultimately failed in clinical trials due to patient relapses. This failure illustrates the need for a drug screening assay that can predict sterile cure by assessing recrudescence after treatment. Here,we used human induced pluripotent stem cell (iPSC)-derived macrophages (iMACs) as host cells for T. cruzi. The iMACs were highly susceptible to infection by the parasites. By combining red fluorescent protein (RFP)-expressing iMACs with mNeonGreen-expressing T. cruzi,we were able to monitor the dynamics of the infection through live cell imaging. The activity of the compounds benznidazole and posaconazole was consistent with the results of an established infection system using mouse primary macrophages. The post-mitotic nature of iMACs makes them suitable host cells for long-term assays needed to assess recrudescence of parasites. Moreover,their human origin,stable genetic background,and capacity for genetic modification make the iMACs excellent host cells for studying host-pathogen interaction. Author summaryThe parasite Trypanosoma cruzi,the causative agent of Chagas disease,is a global health concern affecting millions each year. Infection with T. cruzi can cause chronic disease,often remaining asymptomatic for decades before resulting in severe cardiac or gastro-intestinal pathologies. To date,only benznidazole and nifurtimox are used for treatment of the infection,but both drugs are suboptimal for curing the chronic stage. Posaconazole showed great promise in preclinical studies but failed to achieve sterile cure in clinical trials,causing patient relapses. These disappointing results underline the need for drug screening assays able to predict sterile cure by evaluating recrudescence post-treatment. We used human induced pluripotent stem cell derived macrophages as host cells for T. cruzi and testing of trypanocidal compounds. This model can be used for long-term in vitro screening assays to find new drug candidates against Chagas disease. The human origin of these cells combined with the possibility of upscaling their production make them great host cells for drug screening campaigns. View Publication

We studied the suitability of collagen-based semisolid medium for assay of endogenous erythroid colony formation performed in myeloproliferative disorders. Bone marrow (BM) mononuclear cells (MNC) from 103 patients suspected of having polycythemia vera (PV,76 patients) or essential thrombocythemia (ET,27 patients) were grown in collagen-based,serum-free,cytokine-free semisolid medium. Colony analysis at day 8 or 10 showed that this collagen assay is specific,as endogenous growth of erythroid colonies was never observed in cultures of 16 healthy donors and 6 chronic myelogenous leukemia (CML) patients. Endogenous erythroid colony formation was observed in 53.3% of patients suspected of PV,with only 15.4% of positive cultures for patients with 1 minor PV criterion and 72% (p = 0.009) of positive cultures for patients with textgreater or =2 minor or 1 major PV criterion. Similarly,endogenous growth of erythroid colonies was found in 44.4% of patients suspected of ET,with 31.6% of positive cultures for patients with 1 ET criterion versus 75% for patients with textgreater or =2 ET criteria. In addition,we found that in collagen gels,tests of erythropoietin (EPO) hypersensitivity in the presence of 0.01 or 0.05 U/ml of EPO and tests of endogenous colony-forming units-megakaryocyte (CFU-MK) formation cannot be used to detect PV or ET,as these tests were positive for,respectively,21.4% and 50% of healthy donors and 83% and 50% of CML patients. A retrospective analysis suggests that collagen assays are more sensitive than methylcellulose assays to assess endogenous growth of erythroid colonies. In summary,serum-free collagen-based colony assays are simple and reliable assays of endogenous growth of erythroid colonies in myeloproliferative diseases. They also appear to be more sensitive than methylcellulose-based assays. View Publication

Lipid rafts accumulate in the immunological synapse formed by an organized assembly of the TCR/CD3,LFA-1,and signaling molecules. However,the precise role of lipid rafts in the formation of the immunological synapse is unclear. In this study,we show that LFA-1 on CTL is constitutively active and mediates Ag-independent binding of CTL to target cells expressing its ligands. LFA-1 and CD3 on CTL,but not resting T cells,colocalize in lipid rafts. Binding of LFA-1 on CTL to targets initiates the formation of the immunological synapse,which is formed by LFA-1,CD3,and ganglioside GM1 distributed in the periphery of the cell contact site and cholesterol is more widely distributed. The formation of this synapse is Ag independent,but the recognition of Ag by the TCR induces accumulation of tyrosine phosphorylated proteins in the synapse as well as redistribution of the microtubule organization center toward the cell contact site. Our results suggest that LFA-1 recruits lipid rafts and the TCR/CD3 to the synapse,and facilitates efficient and rapid activation of CTL. View Publication

The human WDR33 gene encodes three major isoforms. The canonical isoform WDR33v1 (V1) is a well-characterized nuclear mRNA polyadenylation factor,while the other two,WDR33v2 (V2) and WDR33v3 (V3),have not been studied. Here,we report that V2 and V3 are generated by alternative polyadenylation,and neither protein contains all seven WD (tryptophan-aspartic acid) repeats that characterize V1. Surprisingly,V2 and V3 are not polyadenylation factors but localize to the endoplasmic reticulum and interact with stimulator of interferon genes (STING),the immune factor that induces the cellular response to cytosolic double-stranded DNA. V2 suppresses interferon-β induction by preventing STING disulfide oligomerization but promotes autophagy,likely by recruiting WIPI2 isoforms. V3,on the other hand,functions to ncrease STING protein levels. Our study has not only provided mechanistic insights into STING regulation but also revealed that protein isoforms can be functionally completely unrelated,indicating that alternative mRNA processing is a more powerful mechanism than previously appreciated. View Publication

Dishevelled-associated activator of morphogenesis1 (DAAM1) is a member of the evolutionarily conserved Formin family and plays a significant role in the malignant progression of various human cancers. This study aims to explore the clinical and biological significance of DAAM1 in pancreatic cancer. Multiple public datasets and an in-house cohort were utilized to assess the clinical relevance of DAAM1 in pancreatic cancer. The LinkedOmics platform was employed to perform enrichment analysis of DAAM1-associated molecular pathways in pancreatic cancer. Subsequently,a series of in vitro and in vivo experiments were conducted to evaluate the biological roles of DAAM1 in pancreatic cancer cells and its effects on intratumoral T cells. DAAM1 was found to be upregulated in pancreatic cancer tissues,with higher expression levels observed in tumor cells. Additionally,high expression of DAAM1 was associated with poor prognosis. DAAM1 acted as an oncogene in pancreatic cancer,and its inhibition suppressed tumor cell proliferation,migration,and invasion,while promoted apoptosis. Furthermore,DAAM1 was involved in the JAK1/STAT1 signaling pathway and regulated PD-L1 expression in pancreatic cancer cells. The inhibition of DAAM1 also significantly reduced the exhaustion levels of CD8+ T cells. In conclusion,DAAM1 functions as an oncogene and is immunologically implicated in pancreatic cancer,these findings suggest that DAAM1 may serve as a promising therapeutic target for the clinical management of pancreatic cancer. The online version contains supplementary material available at 10.1186/s12935-024-03631-8. View Publication