Research
Abstract
MYB fusions are recurrently found in select cancers, including blastic plasmacytoid dendritic cell neoplasm (BPDCN), an acute leukemia with poor prognosis. They are markedly enriched in BPDCN compared to other blood cancers, and in some patients are the only obvious somatic mutation detected. This suggests they may alone be sufficient to drive dendritic cell transformation. MYB fusions are hypothesized to alter the normal transcription factor activity of MYB, but mechanistically how they promote leukemogenesis is poorly understood. Using CUT&RUN chromatin profiling, we found that in BPDCN leukemogenesis, MYB switches from being a regulator of dendritic cell lineage genes to aberrantly regulating G2/M cell cycle control genes. MYB fusions found in BPDCN patients increased the magnitude of DNA binding at these locations, and this was linked to BPDCN-associated gene expression changes. Furthermore, expression of MYB fusions in vivo impaired dendritic cell differentiation and induced transformation to generate a mouse model of myeloid-dendritic acute leukemia. Therapeutically, we present evidence that all-trans retinoic acid (ATRA) may cause loss of MYB protein and cell death in BPDCN.
Authors
Christopher A.G. Booth, Juliette M. Bouyssou, Katsuhiro Togami, Olivier Armand, Hembly G. Rivas, Kezhi Yan, Siobhan Rice, Shuyuan Cheng, Emily M. Lachtara, Jean-Pierre Bourquin, Alex Kentsis, Esther Rheinbay, James A. DeCaprio, Andrew A. Lane
Abstract
T cell receptor (TCR) engagement triggers T cell responses, yet how TCR-mediated activation is regulated at the plasma membrane remains unclear. Here, we report that deleting the membrane scaffolding protein Flotillin-2 (Flot2) increases T cell antigen-sensitivity, resulting in enhanced TCR signaling and effector function to weak TCR stimulation. T cell-specific Flot2-deficient mice exhibited reduced tumor growth and enhanced immunity to infection. Flot2-null CD4+ T cells exhibited increased T helper 1 polarization, proliferation, Nur77 induction, and phosphorylation of ZAP70 and ERK1/2 upon weak TCR stimulation, indicating a sensitized TCR-triggering threshold. Single cell-RNA sequencing suggested that Flot2-null CD4+ T cells follow a similar route of activation as wild-type CD4+ T cells but exhibit higher occupancy of a discrete activation state under weak TCR stimulation. Given prior reports that TCR clustering influences sensitivity of T cells to stimuli, we evaluated TCR distribution with super-resolution microscopy. Flot2 ablation increased the number of surface TCR nanoclusters on naïve CD4+ T cells. Collectively, we posit that Flot2 modulates T cell functionality to weak TCR stimulation, at least in part, by regulating surface TCR clustering. Our findings have implications for improving T cell reactivity in diseases with poor antigenicity, such as cancer and chronic infections.
Authors
Sookjin Moon, Fei Zhao, Mohammad N. Uddin, Charles J. Tucker, Peer W.F. Karmaus, Michael B. Fessler
Abstract
Retinitis pigmentosa (RP) is a complex group of inherited retinal diseases characterized by progressive death of photoreceptor cells and eventual blindness. Pde6a, which encodes a cGMP-specific phosphodiesterase, is a crucial pathogenic gene for autosomal recessive RP (RP43); there is no effective therapy for this form of RP. The compact CRISPR/SaCas9 system, which can be packaged into a single adeno-associated virus, holds promise for simplifying effective gene therapy. Here, we demonstrated that all-in-one AAV-SaCas9-mediated Nrl gene inactivation can efficiently prevent retinal degeneration in a RP mouse model with Pde6anmf363/nmf363 mutation. We screened single guide RNAs (sgRNAs) capable of efficiently editing mouse Nrl gene in N2a cells and then achieved effective gene editing by using a single AAV to co-deliver SaCas9 and an optimal Nrl-sg2 into the mouse retina. Excitingly, in vivo inactivation of Nrl improved photoreceptor cell survival and rescued retinal function in treated Pde6a deficient mice. Thus, we showed that a practical, gene-independent method, AAV-SaCas9-mediated Nrl inactivation, holds promise for future therapeutic applications in patients with RP.
Authors
Zhiquan Liu, Siyu Chen, Chien-Hui Lo, Qing Wang, Yang Sun
Abstract
Thrombopoietin (TPO) is a plasma glycoprotein that binds its receptor on megakaryocytes (MK) and MK progenitors, resulting in enhanced platelet production. The mechanism by which TPO is secreted from hepatocytes remains poorly understood. LMAN1 and MCFD2 form a complex at the endoplasmic reticulum membrane, recruiting cargo proteins into COPII vesicles for secretion. In this study, we showed that LMAN1 deficient mice (with complete germline LMAN1 deficiency) exhibited mild thrombocytopenia, whereas the platelet count was entirely normal in mice with approximately 7% Lman1 expression. Surprisingly, mice deleted for Mcfd2 did not exhibit thrombocytopenia. Analysis of peripheral blood from LMAN1 deficient mice demonstrated normal platelet size and normal morphology of dense and alpha granules. LMAN1 deficient mice exhibited a trend toward reduced MK and MK progenitors in the bone marrow. We next showed that hepatocyte-specific but not hematopoietic Lman1 deletion results in thrombocytopenia, with plasma TPO level reduced in LMAN1 deficient mice, despite normal Tpo mRNA levels in LMAN1 deficient livers. TPO and LMAN1 interacted by co-immunoprecipitation in a heterologous cell line and TPO accumulated intracellularly in LMAN1 deleted cells. Altogether, these studies confirmed the hepatocyte as the cell of origin for TPO production in vivo and were consistent with LMAN1 as the endoplasmic reticulum cargo receptor that mediates the efficient secretion of TPO. To our knowledge, TPO is the first example of an LMAN1-dependent cargo that is independent of MCFD2.
Authors
Lesley A. Everett, Zesen Lin, Ann Friedman, Vi T. Tang, Greggory Myers, Ginette Balbin-Cuesta, Richard King, Guojing Zhu, Beth McGee, Rami Khoriaty
Abstract
Given the potential fundamental function of osteal macrophages in bone pathophysiology, we study here their precise function in experimental osteoporosis. Gene profiling of osteal macrophages from ovariectomized mice demonstrated the upregulation of genes that were involved in oxidative stress, cell senescence and apoptotic process. A scRNA-seq analysis revealed that osteal macrophages were heterogenously clustered into 6 subsets that expressed proliferative, inflammatory, anti-inflammatory and efferocytosis gene signatures. Importantly, postmenopausal mice exhibited a 20-fold increase in subset-3 that showed a typical gene signature of cell senescence and inflammation. These findings suggest that the decreased production of estrogen due to postmenopause altered the osteal macrophages subsets, resulting in a shift toward cell senescence and inflammatory conditions in the bone microenvironment. Furthermore, adoptive macrophage transfer onto calvarial bone was performed and mice that received oxidative-stressed macrophages exhibited greater osteolytic lesions than control macrophages, suggesting the role of these cells in development of inflammaging in bone microenvironment. Consistently, depletion of senescent cells and oxidative-stressed macrophages subset alleviated the excessive bone loss in postmenopausal mice. Our data provided a new insight into the pathogenesis of osteoporosis and sheds light on a new therapeutic approach for the treatment/prevention of postmenopausal osteoporosis.
Authors
Yoshio Nishida, M. Alaa Terkawi, Gen Matsumae, Shunichi Yokota, Taiki Tokuhiro, Yuki Ogawa, Hotaka Ishizu, Junki Shiota, Tsutomu Endo, Hend Alhasan, Taku Ebata, Keita Kitahara, Tomohiro Shimizu, Daisuke Takahashi, Masahiko Takahata, Ken Kadoya, Norimasa Iwasaki
Abstract
Cutaneous wound healing is a slow process that often terminates with permanent scarring while oral wounds, in contrast, regenerate damage faster. Unique molecular networks in epidermal and oral epithelial keratinocytes contribute to the tissue-specific response to wounding, but key factors that establish those networks and how the keratinocytes interact with their cellular environment remain to be elucidated. The transcription factor PITX1 is highly expressed in the oral epithelium but is undetectable in cutaneous keratinocytes. To delineate if PITX1 contributes to oral keratinocyte identity, cell-cell interactions, and the improved wound healing capabilities, we ectopically expressed PITX1 in the epidermis of murine skin. Using comparative analysis of murine skin and oral (buccal) mucosa with scRNA-seq and spatial transcriptomics, we found that PITX1 expression enhances epidermal keratinocyte migration, proliferation, and alters differentiation to a quasi-oral keratinocyte state. PITX1+ keratinocytes reprogram intercellular communication between skin-resident cells to mirror buccal tissue while also stimulating the influx of neutrophils that establish a pro-inflammatory environment. Furthermore, PITX1+ skin heals significantly faster than control skin via increased keratinocyte activation and migration and a tunable inflammatory environment. These results illustrate that PITX1 programs oral keratinocyte identity and cellular interactions while also revealing critical downstream networks that promote wound closure.
Authors
Andrew M. Overmiller, Akihiko Uchiyama, Emma D. Hope, Subhashree Nayak, Christopher G. O'Neill, Kowser Hasneen, Yi-Wen Chen, Faiza Naz, Stefania Dell'Orso, Stephen R. Brooks, Kan Jiang, Maria I. Morasso.
Abstract
Rheumatoid arthritis (RA) is one of the most common autoimmune disorders and is characterized by exacerbated joint inflammation that can lead to tissue remodeling and autoantigen generation. Despite the well-documented accumulation of the serine protease Granzyme B (GzmB) in the biospecimens of patients with RA, little is understood pertaining to its role in pathobiology. In the present study Tenascin-C (TN-C), a large extracellular matrix glycoprotein and an endogenous trigger of inflammation, was identified as a substrate for GzmB in RA. GzmB cleaves TN-C in vitro to generate three fragments: a 130 kDa fragment that remains anchored to the matrix, and two 70 and 30 kDa fragments that are released and solubilized. Mass spectrometry results seem to indicate that the 30 kDa fragment generated by GzmB most likely contains TN-C pro-inflammatory C-terminal fibrinogen-like domain. Soluble levels of GzmB and TN-C are also significantly elevated in the synovial fluids of RA patients compared to healthy controls, with two 70 kDa and 30 kDa soluble TN-C fragments detectable in the synovial fluids of RA patients. The molecular weights of these fragments coincide with those generated by GzmB in vitro, suggesting that GzmB also cleaves TN-C in RA patients. Granzyme K (GzmK), another member of the granzyme family, also cleaves TN-C in vitro. However, unlike GzmB, the molecular weights of TN-C fragments generated by GzmK in vitro do not correspond to fragments identified in patients. Altogether, our data supports the contribution of Granzyme B, but not Granzyme K, to RA through the cleavage of Tenascin-C.
Authors
Alexandre Aubert, Amy Liu, Martin Kao, Jenna Goeres, Katlyn C. Richardson, Lorenz Nierves, Karen Jung, Layla Nabai, Hongyan Zhao, Gertraud Orend, Roman Krawetz, Philipp F. Lange, Alastair Younger, Jonathan Chan, David J. Granville
Abstract
Lineage plasticity mediates resistance to androgen receptor pathway inhibitors (ARPIs) and progression from adenocarcinoma to neuroendocrine prostate cancer (NEPC), a highly aggressive and poorly understood subtype. ASCL1 has emerged as a central regulator of the lineage plasticity driving neuroendocrine differentiation. Here, we showed that ASCL1 was reprogrammed in ARPI-induced transition to the terminal NEPC and identified that the ASCL1 binding pattern tailored the expression of lineage-determinant transcription factor combinations that underlying discrete terminal NEPC identity. Notably, we identified FOXA2 as a major co-factor of ASCL1 in terminal NEPC, which is highly expressed in ASCL1-driven NEPC. Mechanistically, FOXA2 and ASCL1 interacted and worked in concert to orchestrate terminal neuronal differentiation. We identified that Prospero-Related Homeobox 1 was a target of ASCL1 and FOXA2. Targeting prospero-related homeobox 1 abrogated neuroendocrine characteristics and led to a decrease in cell proliferation in vitro and tumor growth in vivo. Our findings provide insights into the molecular conduit underlying the interplay between different lineage-determinant transcription factors to support the neuroendocrine identity and nominate prospero-related homeobox 1 as a potential target in ASCL1 high NEPC.
Authors
Shaghayegh Nouruzi, Takeshi Namekawa, Nakisa Tabrizian, Maxim Kobelev, Olena Sivak, Joshua M. Scurll, Cassandra Jingjing Cui, Dwaipayan Ganguli, Amina Zoubeidi
Abstract
Despite the advances in the understanding and treatment of myeloproliferative neoplasm (MPN), the disease remains incurable with the risk of evolution to AML or myelofibrosis (MF). Unfortunately, the evolution of the disease to MF remains still poorly understood impeding preventive and therapeutic options. Recent studies in solid tumor microenvironment and organ fibrosis have shed instrumental insights on their respective pathogenesis and drug resistance, yet such precise data are lacking in MPN. In this study, through a patient-sample driven transcriptomic and epigenetic description of the MF microenvironment landscape and cell-based analyses, we identify HOXB7 overexpression and more precisely a novel TGFβ-Wnt-HOXB7 pathway as associated to a pro-fibrotic and pro-osteoblastic biased differentiation of mesenchymal stromal cells (MSCs). Using gene-based and chemical inhibition of this pathway we reverse the abnormal phenotype of MSCs from myelofibrosis patients, providing the MPN field with a potential novel target to prevent and manage evolution to MF.
Authors
Saravanan Ganesan, Sarah Awan-Toor, Fabien Guidez, Nabih Maslah, Rifkath Rahimy, Céline Aoun, Panhong Gou, Chloé Guiguen, Juliette Soret, Odonchimeg Ravdan, Valeria Bisio, Nicolas Dulphy, Camille Lobry, Marie-Hélène Schlageter, Michèle Souyri, Stéphane Giraudier, Jean-Jacques Kiladjian, Christine Chomienne, Bruno Cassinat
Abstract
Opioid use may impact the HIV-1 reservoir and its reversal from latency. We studied forty-seven virally suppressed people with HIV (PWH) and observed that lower concentration of HIV-1 latency reversal agents (LRA), used in combination with small molecules that did not reverse latency, synergistically increased the magnitude of HIV-1 re-activation ex vivo, regardless of opioid use. This LRA boosting, which combined a Smac mimetic or low-dose protein kinase C agonist with histone deacetylase inhibitors, generated significantly more unspliced HIV-1 transcription than phorbol 12-myristate 13-acetate (PMA) with ionomycin (PMAi), the maximal known HIV-1 reactivator. LRA boosting associated with greater histone acetylation, modulated surface activation-induced markers, and altered T cell production of TNFα, IL-2, and IFNγ. HIV-1 reservoirs in PWH contained unspliced and polyadenylated (polyA) virus mRNA, the ratios of which were greater in resting than total CD4+ T cells and correct to 1:1 with PMAi exposure. We characterized treated suppressed HIV-1 infection as a period of inefficient, not absent, virus transcription. Multiply spliced HIV-1 transcripts and virion production did not consistently increase with LRA boosting, suggesting the presence of a persistent post-transcriptional block. LRA boosting can be leveraged to probe mechanisms of an effective cellular HIV-1 latency reversal program.
Authors
Tyler J. Lilie, Jennifer Bouzy, Archana Asundi, Jessica Taylor, Samantha Roche, Alex Olson, Kendyll Coxen, Heather Corry, Hannah Jordan, Kiera Clayton, Nina Lin, Athe Tsibris
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