Abnormal alternative splicing (AS) caused by alterations of splicing factors contributes to tumor progression. Serine/arginine splicing factor 1 (SRSF1) has emerged as a key oncodriver in numerous solid tumors, leaving its roles and mechanisms largely obscure in glioma. Herein we demonstrated that SRSF1 was increased in glioma tissues and cell lines. Moreover, its expression was correlated positively with tumor grade and Ki-67 index, but inversely with patients’ survival. Using RNA-seq, we comprehensively screened and identified multiple SRSF1-affected AS events. Motif analysis revealed a position-dependent modulation of AS by SRSF1 in glioma. Functionally, we verified that SRSF1 promoted cell proliferation, survival and invasion by specifically switching the AS of myosin IB (MYO1B) gene and facilitating the expression of the oncogenic and membrane-localized isoform, MYO1B-fl. Strikingly, MYO1B splicing was dysregulated in parallel with SRSF1 expression in gliomas, and predicted the poor prognosis of the patients. Further investigation revealed that SRSF1-guided AS of MYO1B gene increased the tumorigenic potentials of glioma cells through the PDK1/AKT and PAK/LIMK pathways. Taken together, we identify SRSF1 as an important oncodriver, which integrates the AS controlling of MYO1B into promotion of gliomagenesis, and represents a potential prognostic biomarker and target for glioma therapy.
Xuexia Zhou, Run Wang, Xuebing Li, Lin Yu, Dan Hua, Cuiyun Sun, Cuijuan Shi, Wenjun Luo, Chun Rao, Zhendong Jiang, Ying Feng, Qian Wang, Shizhu Yu
Immune checkpoint therapies have shown tremendous promise in cancer therapy. However, tools to assess their target engagement, and hence ability to predict their efficacy, have been lacking. Here, we show that target engagement and tumor residence kinetics of antibody therapeutics targeting the programmed death ligand-1 (PD-L1) can be quantified non-invasively. In computational docking studies, we observed that PD-L1-targeted antibodies (atezolizumab, avelumab, durvalumab) and a high affinity PD-L1 binding peptide, WL12, have common interaction sites on PD-L1. Using the peptide radiotracer [64Cu]WL12 in vivo, we employed positron emission tomography (PET) imaging and biodistribution studies, in multiple xenograft models and demonstrated that variable PD-L1 expression and its saturation by atezolizumab, avelumab, and durvalumab can be quantified independent of biophysical properties and pharmacokinetics of antibodies. Next, we used [64Cu]WL12 to evaluate the impact of time and dose on free fraction of tumor PD-L1 levels during treatment. These quantitative measures enabled, by mathematical modeling, prediction of antibody doses needed to achieve therapeutically effective occupancy (defined as >90%). Thus, we show that peptide-based PET is a promising tool for optimizing dose and therapeutic regimens employing PD-L1 checkpoint antibodies, and can be used for improving therapeutic efficacy.
Dhiraj Kumar, Ala Lisok, Elyes Dahmane, Matthew D. McCoy, Sagar Shelake, Samit Chatterjee, Viola Allaj, Polina Sysa-Shah, Bryan Wharram, Wojciech G. Lesniak, Ellen Tully, Edward Gabrielson, Elizabeth M. Jaffee, John T. Poirier, Charles M. Rudin, Jogarao V.S. Gobburu, Martin G. Pomper, Sridhar Nimmagadda
Macrophages perform key functions in tissue homeostasis that are influenced by the local tissue environment. Within the tumor microenvironment tumor associated macrophages can be altered to acquire properties that enhance tumor growth. Here, we found lactate, a metabolite found in high concentration within the anaerobic tumor environment, activated mTORC1 that subsequently suppressed TFEB-mediated expression of a macrophage-specific vacuolar ATPase subunit ATP6V0d2. Atp6v0d2-/- mice were more susceptible to tumor growth with enhanced HIF-2α-mediated VEGF production in macrophages that display a more protumoral phenotype. We found that ATP6V0d2 targeted HIF-2α but not HIF-1α for lysosome-mediated degradation. Blockade of HIF-2α transcriptional activity reversed the susceptibility of Atp6v0d2-/- mice to tumor development. Furthermore, in a cohort of patients with lung adenocarcinoma, expression of ATP6V0d2 and HIF-2α was positively and negatively correlated with survival respectively, suggesting a critical role of the macrophage lactate-ATP6V0d2-HIF-2α axis in maintaining tumor growth in human patients. Together, our results highlight the ability of tumor cells to modify the function of tumor-infiltrating macrophages to optimize the microenvironment for tumor growth.
Na Liu, Jing Luo, Dong Kuang, Sanpeng Xu, Yaqi Duan, Yu Xia, Zhengping Wei, Xiuxiu Xie, Bingjiao Yin, Fang Chen, Shunqun Luo, Huicheng Liu, Jing Wang, Kan Jiang, Feili Gong, Zhao-hui Tang, Xiang Cheng, Huabin Li, Zhuoya Li, Arian Laurence, Guoping Wang, Xiang-Ping Yang
Ca2+ channel β-subunit interactions with pore-forming α-subunits are long-thought to be obligatory for channel trafficking to the cell surface and for tuning of basal biophysical properties in many tissues. Unexpectedly, we demonstrate that transgenic expression of mutant cardiac α1C subunits lacking capacity to bind CaVβ because of alanine-substitutions of three conserved residues — Y467, W470, and I471 in the α-interaction domain of rabbit α1C — can traffic to the sarcolemma in adult cardiomyocytes in vivo and sustain normal excitation-contraction coupling. However, these β-less Ca2+ channels cannot be stimulated by β-adrenergic pathway agonists, and thus adrenergic-augmentation of contractility is markedly impaired in isolated cardiomyocytes and in hearts. Similarly, viral-mediated expression of a β-subunit-sequestering-peptide sharply curtailed β-adrenergic stimulation of wild-type Ca2+ channels, identifying an approach to specifically modulate β-adrenergic regulation of cardiac contractility. Our data demonstrate that β subunits are required for β-adrenergic regulation of CaV1.2 channels and positive inotropy in the heart, but are dispensable for CaV1.2 trafficking to the adult cardiomyocyte cell surface, and for basal function and excitation-contraction coupling.
Lin Yang, Alexander Katchman, Jared S. Kushner, Alexander Kushnir, Sergey I. Zakharov, Bi-xing Chen, Zunaira Shuja, Prakash Subramanyam, Guoxia Liu, Arianne Papa, Daniel D. Roybal, Geoffrey S. Pitt, Henry M. Colecraft, Steven O. Marx
Current thalassemia gene therapy protocols require the collection of hematopoietic stem/progenitor cells (HSPCs), in vitro culture, lentivirus vector transduction, and retransplantation into myelo-ablated patients. Because of cost and technical complexity, it is unlikely that such protocols will be applicable in developing countries where the greatest demand for a beta-thalassemia therapy lies. We have developed a simple in vivo HSPC gene therapy approach that involved HSPC mobilization and an intravenous injection of integrating HDAd5/35++ vectors. Transduced HSPCs homed back to the bone marrow where they persisted long-term. HDAd5/35++ vectors for in vivo gene therapy of thalassemia had a unique capsid that targeted primitive HSPCs through human CD46, a relatively safe SB100X transposase-based integration machinery, a micro-LCR driven gamma-globin gene and, a MGMT(P140K) system that allowed for increasing the therapeutic effect by short-term treatment with low-dose O6BG/BCNU. We showed in “healthy” human CD46 transgenic mice and in a mouse model of thalassemia intermedia that our in vivo approach resulted in stable gamma-globin expression in the majority of circulating red blood cells. The high marking frequency was maintained in secondary recipients. In the thalassemia model, a near complete phenotypic correction was achieved. The treatment was well tolerated. This cost-efficient and “portable” approach could permit a broader clinical application of thalassemia gene therapy.
Hongjie Wang, Aphrodite Georgakopoulou, Nikoletta Psatha, Chang Li, Chrysi Capsali, Himanshu Bhusan Samal, Achilles Anagnostopoulos, Anja Ehrhardt, Zsuzsanna Izsvák, Thalia Papayannopoulou, Evangelia Yannaki, André Lieber
Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disorder characterized by accelerated cardiovascular disease with extensive fibrosis. It is caused by a mutation in LMNA leading to expression of truncated prelamin A (progerin) in the nucleus. To investigate the contribution of the endothelium to cardiovascular HGPS pathology, we generated an endothelium-specific HGPS mouse model with selective endothelial progerin expression. Transgenic mice develop interstitial myocardial and perivascular fibrosis and left ventricular hypertrophy associated with diastolic dysfunction and premature death. Endothelial cells show impaired shear stress response and reduced levels of endothelial nitric oxide synthase (eNOS) and NO. On the molecular level, progerin impairs nucleocytoskeletal coupling in endothelial cells through changes in mechanoresponsive components at the nuclear envelope, increased F-/G-actin ratios and deregulation of mechanoresponsive myocardin-related transcription factor-A (MRTFA). MRTFA binds to the Nos3 promoter reducing eNOS expression, thereby mediating a pro-fibrotic paracrine response in fibroblasts. MRTFA inhibition rescues eNOS levels and ameliorates the pro-fibrotic effect of endothelial cells in vitro. Although this murine model lacks the key anatomical feature of vascular smooth muscle cell loss seen in HGPS patients, our data show that progerin-induced impairment of mechanosignaling in endothelial cells contributes to excessive fibrosis and cardiovascular disease in HGPS patients.
Selma Osmanagic-Myers, Attila Kiss, Christina Manakanatas, Ouafa Hamza, Franziska Sedlmayer, Petra L. Szabo, Irmgard Fischer, Petra Fichtinger, Bruno K. Podesser, Maria Eriksson, Roland Foisner
Despite showing success in treating melanoma and haematological malignancies, adoptive cell therapy (ACT) has generated only limited effects in solid tumors. This is, in part, due to a lack of specific antigen targets, poor trafficking/infiltration and immunosuppression in the tumor microenvironment. In this study, we combined ACT with oncolytic virus vaccines (OVV) to drive expansion and tumor infiltration of transferred antigen-specific T cells, and demonstrated that the combination is highly potent for the eradication of established solid tumors. Consistent with other successful immunotherapies, this approach elicited severe autoimmune consequence when the antigen targeted was a self-protein. However, modulation of IFNα/β signaling, either by functional blockade or rational choice of an OVV backbone, ameliorated autoimmune side effects without compromising antitumor efficacy. Our study uncovers a pathogenic role for IFNα/β in facilitating autoimmune toxicity during cancer immunotherapy and offers a safe and powerful combinatorial regimen with immediate translational applications.
Scott R. Walsh, Donald Bastin, Lan Chen, Andrew Nguyen, Christopher J. Storbeck, Charles Lefebvre, David Stojdl, Jonathan L. Bramson, John C. Bell, Yonghong Wan
X-linked dominant incontinentia pigmenti (IP) and X-linked recessive anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) are caused by loss-of-function and hypomorphic NEMO mutations, respectively. We describe a European mother with mild IP and a Japanese mother without IP, whose three boys with EDA-ID died of immunodeficiency. We identify the same private variant in an intron of IKBKG/NEMO, IVS4+866 C>T, which was inherited from and occurred de novo in the European and Japanese mothers, respectively. This mutation creates a new splicing donor site, giving rise to a 44-nucleotide pseudo-exon generating a frameshift. Its leakiness accounts for NF-κB activation being impaired, but not abolished in the boys’ cells. However, aberrant splicing rates differ between cell types, with WT NEMO mRNA and protein levels ranging from barely detectable in leukocytes to residual amounts in iPSC-derived macrophages, and higher levels in fibroblasts and iPSC-derived neuronal precursor cells. Finally, SRSF6 binds to the pseudo-exon, facilitating its inclusion. Moreover, SRSF6 knockdown or CLK inhibition restores WT NEMO expression and function in mutant cells. A recurrent deep intronic splicing mutation in IKBKG/NEMO underlies a purely quantitative NEMO defect in males that is most severe in leukocytes and can be rescued by the inhibition of SRSF6 or CLK.
Bertrand Boisson, Yoshitaka Honda, Masahiko Ajiro, Jacinta Bustamante, Matthieu Bendavid, Andrew R. Gennery, Yuri Kawasaki, Jose Ichishima, Mitsujiro Osawa, Hiroshi Nihira, Takeshi Shiba, Takayuki Tanaka, Maya Chrabieh, Benedetta Bigio, Hong Hur, Yuval Itan, Yupu Liang, Satoshi Okada, Kazushi Izawa, Ryuta Nishikomori, Osamu Ohara, Toshio Heike, Laurent Abel, Anne Puel, Megumu K. Saito, Jean-Laurent Casanova, Masatoshi Hagiwara, Takahiro Yasumi
Hereditary angioedema (HAE) is an autosomal dominant disease characterized by recurrent edema attacks associated with morbidity and mortality. HAE results from variations in the SERPING1 gene encoding C1 inhibitor (C1INH), a serine protease inhibitor (serpin). Reduced plasma levels of C1INH lead to enhanced activation of the contact system triggering high levels of bradykinin and increased vascular permeability, but the cellular mechanisms leading to low C1INH levels (20-30% of normal) in heterozygous HAE type I patients remain obscure. Here, we showed that C1INH encoded by a subset of HAE-causing SERPING1 alleles affected secretion of normal C1INH protein in a dominant negative fashion by triggering formation of protein-protein interactions between normal and mutant C1INH leading to creation of larger intracellular C1INH aggregates that were trapped in the endoplasmic reticulum (ER). Notably, intracellular aggregation of C1INH and ER abnormality were observed in fibroblasts from a heterozygous carrier of a dominant negative SERPING1 gene variant, but the condition was ameliorated by viral delivery of the SERPING1 gene. Collectively, our data link abnormal accumulation of serpins, a hallmark of serpinopathies, with dominant negative disease mechanisms affecting C1INH plasma levels in HAE type I patients and may pave the way for new treatments of HAE.
Didde Haslund, Laura Barrett Ryø, Sara Seidelin Majidi, Iben Kløvgaard Rose, Kristian Alsbjerg Skipper, Tue Fryland, Anja Bille Bohn, Claus Koch, Martin K. Thomsen, Yaseelan Palarasah, Thomas J. Corydon, Anette Bygum, Lene N. Nejsum, Jacob Giehm Mikkelsen
The negatively charged sugar sialic acid (Sia) occupies the outermost position in the bulk of cell surface glycans. Lack of sialylated glycans due to genetic ablation of the Sia activating enzyme CMP-sialic acid synthase (CMAS) resulted in embryonic lethality around day 9.5 post coitum (E9.5) in mice. Developmental failure was caused by complement activation on trophoblasts in Cmas-/- implants accompanied by infiltration of maternal neutrophils at the fetal-maternal interface, intrauterine growth restriction, impaired placental development and a thickened Reichert’s membrane. This phenotype, which shared features with complement-recepter-1 related protein Y (Crry) depletion, was rescued in E8.5 Cmas-/- mice upon injection of cobra venom factor resulting in exhaustion of the maternal complement component C3. Here we show that Sia is dispensable for early development of the embryo proper, but pivotal for fetal-maternal immune homeostasis during pregnancy, i.e. for protecting the allograft implant against attack by the maternal innate immune system. Finally, embryos devoid of cell surface sialylation suffered from malnutrition due to inadequate placentation as secondary effect.
Markus Abeln, Iris Albers, Ulrike Peters-Bernard, Kerstin Flächsig-Schulz, Elina Kats, Andreas Kispert, Stephen Tomlinson, Rita Gerardy-Schahn, Anja Münster-Kühnel, Birgit Weinhold
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