Research Article
Abstract
The cystine-xCT transporter/glutathione/GPX4 axis is the canonical pathway protecting cells from ferroptosis. Whereas GPX4-targeting ferroptosis-inducing compounds (FINs) act independently of mitochondria, xCT-targeting FINs require mitochondrial lipid peroxidation, though the mechanism remains unclear. Because cysteine is also a precursor for coenzyme A (CoA) biosynthesis, here, we demonstrated that CoA supplementation selectively prevented ferroptosis triggered by xCT inhibition by regulating the mitochondrial thioredoxin system. Our data showed that CoA regulated the in vitro enzymatic activity of mitochondrial thioredoxin reductase-2 (TXNRD2) by covalently modifying the thiol group of cysteine (CoAlation) on Cys-483. Replacing Cys-483 with alanine on TXNRD2 abolished its enzymatic activity and ability to protect cells against ferroptosis. Targeting xCT to limit cysteine import and, therefore, CoA biosynthesis reduced CoAlation on TXNRD2. Furthermore, the fibroblasts from patients with disrupted CoA metabolism had increased mitochondrial lipid peroxidation. In organotypic brain slice cultures, inhibition of CoA biosynthesis led to an oxidized thioredoxin system, increased mitochondrial lipid peroxidation, and loss of cell viability, which were all rescued by ferrostatin-1. These findings identified CoA-mediated posttranslational modification to regulate the thioredoxin system as an alternative ferroptosis protection pathway with potential clinical relevance for patients with disrupted CoA metabolism.
Authors
Chao-Chieh Lin, Yi-Tzu Lin, Ssu-Yu Chen, Yasaman Setayeshpour, Yubin Chen, Denise E. Dunn, Taylor Nguyen, Alexander A. Mestre, Adrija Banerjee, Lalitha Guruprasad, Erik J. Soderblom, Guo-Fang Zhang, Chen-Yong Lin, Valeriy Filonenko, Suh Young Jeong, Scott R. Floyd, Susan J. Hayflick, Ivan Gout, Jen-Tsan Chi
Abstract
Elevated glucocorticoid levels are common in conditions such as aging, chronic stress, Cushing syndrome, and glucocorticoid therapy. While glucocorticoids suppress inflammation through the glucocorticoid receptor (GR), they also cause metabolic side effects. Investigating alternative pathways beyond GR activation is crucial for reducing these side effects. Our phosphoproteomics analysis revealed that glucocorticoid exposure promotes phosphorylation at the RxxS motifs of multiple proteins in preadipocytes, including those mediated by serum- and glucocorticoid-induced kinase 3 (SGK3). SGK3 is a key mediator of glucocorticoid-induced adipogenesis, as shown by impaired adipogenesis after SGK3 inhibition or genetic ablation. Sgk3-KO mice were resistant to obesity induced by glucocorticoid or a high-fat diet, and proteolysis targeting chimeras (PROTAC) targeting SGK3 reduced adipogenesis in both obese mice and in a thyroid eye disease cell line. Mechanistically, SGK3 translocated to the nucleus upon glucocorticoid stimulation, interacted with and phosphorylated the BRG1 subunit of the BAF complex, and prevented BRG1 degradation, promoting chromatin remodeling necessary for adipogenesis. These findings highlight SGK3 as a potential therapeutic target to mitigate metabolic side effects of elevated glucocorticoid levels.
Authors
Qilong Chen, Jialu Guo, Yuyi Liu, Tai Du, Jiapei Liu, Yuyao Zhang, Yuming Dai, Mengdi Zhang, Ziqian Zhou, Qiyang Zhang, Caixia Wei, Qiurong Ding, Jun Qin, Qiwei Zhai, Ju Qiu, Mengle Shao, Fang Zhang, Alexander A. Soukas, Ben Zhou
Abstract
BRD4 is an epigenetic reader protein that regulates oncogenes such as myc in cancer. However, its additional role in shaping immune responses via regulation of inflammatory and myeloid cell responses is not yet fully understood. This work further characterized the multifaceted role of BRD4 in antitumor immunity. Nanostring gene expression analysis of EMT6 tumors treated with a BRD4 inhibitor identified a reduction in myeloid gene expression signatures. Additionally, BRD4 inhibition significantly reduced myeloid-derived suppressor cells (MDSCs) in the spleens and tumors of mice in multiple tumor models and also decreased the release of tumor-derived MDSC growth and chemotactic factors. Pharmacologic inhibition of BRD4 in MDSCs induced apoptosis and modulated expression of apoptosis regulatory proteins. A BRD4 myeloid–specific knockout model suggested that the dominant mechanism of MDSC reduction after BRD4 inhibition was primarily through a direct effect on MDSCs. BRD4 inhibition enhanced anti–PD-L1 therapy in the EMT6, 4T1, and Lewis lung carcinoma tumor models, and the efficacy of the combination treatment was dependent on CD8+ T cells and on BRD4 expression in the myeloid compartment. These results identify BRD4 as a regulator of MDSC survival and provide evidence to further investigate BRD4 inhibitors in combination with immune-based therapies.
Authors
Himanshu Savardekar, Andrew Stiff, Alvin Liu, Robert Wesolowski, Emily Schwarz, Ian C. Garbarine, Megan C. Duggan, Sara Zelinskas, Jianying Li, Gabriella Lapurga, Alexander Abreo, Lohith Savardekar, Ryan Parker, Julia Sabella, Mallory J. DiVincenzo, Brooke Benner, Steven H. Sun, Dionisia Quiroga, Luke Scarberry, Gang Xin, Anup Dey, Keiko Ozato, Lianbo Yu, Merve Hasanov, Debasish Sundi, Richard C. Wu, Kari L. Kendra, William E. Carson III
Abstract
The leukemia fusion gene CBFB-MYH11 requires RUNX1 for leukemogenesis, but the underlying mechanism is unclear. By in vitro studies, we found that CBFβ-SMMHC, the chimeric protein encoded by CBFB-MYH11, could enhance the binding affinity between RUNX1 and its target DNA. Increased RUNX1-DNA binding was also observed in myeloid progenitor cells from mice expressing CBFβ-SMMHC. Moreover, only CBFβ-SMMHC variants able to enhance the DNA binding affinity by RUNX1 could induce leukemia in mouse models. Marked transcriptomic changes, affecting genes associated with inflammatory response and target genes of CBFA2T3, were observed in mice expressing leukemogenic CBFβ-SMMHC variants. Finally, we show that CBFβ-SMMHC could not induce leukemia in mice with a Runx1-R188Q mutation, which reduces RUNX1 DNA binding but does not affect its interaction with CBFβ-SMMHC or its sequestration to cytoplasm by CBFβ-SMMHC. Our data suggest that, in addition to binding RUNX1 to regulate gene expression, enhancing RUNX1 binding affinity to its target DNA is an important mechanism by which CBFβ-SMMHC contributes to leukemogenesis, highlighting RUNX1-DNA interaction as a potential therapeutic target in inv(16) acute myeloid leukemia.
Authors
Tao Zhen, Yaqiang Cao, Tongyi Dou, Yun Chen, Guadalupe Lopez, Ana Catarina Menezes, Xufeng Wu, John A. Hammer, Jun Cheng, Lisa Garrett, Stacie Anderson, Martha Kirby, Stephen Wincovitch, Bayu Sisay, Abdel G. Elkahloun, Di Wu, Lucio H. Castilla, Wei Yang, Jiansen Jiang, Keji Zhao, P. Paul Liu
Abstract
Acute ischemic organ diseases such as acute myocardial infarction and acute kidney injury often result in irreversible tissue damage and progress to chronic heart failure (CHF) and chronic kidney disease (CKD), respectively. However, the molecular mechanisms underlying the development of CHF and CKD remain incompletely understood. Here, we show that mice deficient in CD300a, an inhibitory immunoreceptor expressed on myeloid cells, showed enhanced efferocytosis by tissue-resident macrophages and decreased damage-associated molecular patterns and pathogenic SiglecFhi neutrophils, resulting in milder inflammation-associated tissue injury than in wild-type mice after ischemia and reperfusion (IR). Notably, we uncovered that CD300a deficiency on SiglecFlo neutrophils increased the signal transducer and activator of transcription 3–mediated production of pro-angiogenic and antifibrotic factors, resulting in milder adverse remodeling after IR. Our results demonstrated that CD300a plays an important role in the pathogenesis of ischemic tissue injury and adverse remodeling in the heart and kidney.
Authors
Nanako Nishiyama, Hitoshi Koizumi, Chigusa Nakahashi-Oda, Satoshi Fujiyama, Xuewei Ng, Hanbin Lee, Fumie Abe, Jinao Li, Yan Xu, Takehito Sugasawa, Kazuko Tajiri, Taketaro Sadahiro, Masaki Ieda, Keiji Tabuchi, Kazuko Shibuya, Akira Shibuya
Abstract
BACKGROUND A key objective in managing HPV+ oropharyngeal squamous cell carcinoma (OPSCC) is reducing radiation therapy (RT) doses without compromising cure rates. A recent phase II/III HN005 trial revealed that clinical factors alone are insufficient to guide safe RT dose de-escalation. Our prior research demonstrated that the genomic adjusted radiation dose (GARD) predicts RT benefit and may inform dose selection. We hypothesize that GARD can guide personalized RT de-escalation in HPV+ OPSCC patients.METHODS Gene expression profiles were analyzed in 191 HPV+ OPSCC patients enrolled in an international, multi-institutional observational study (AJCC Eighth Edition, stages I–III). Most patients received 70 Gy in 35 fractions or 69.96 Gy in 33 fractions (median dose: 70 Gy; range: 51.0–74.0 Gy). Overall survival (OS) was 94.1% at 36 months and 87.3% at 60 months. A Cox proportional hazards model assessed association between GARD and OS, and time-dependent receiver operating characteristic analyses compared GARD with traditional clinical predictors.RESULTS Despite uniform RT dosing, GARD showed wide heterogeneity, ranging from 15.4 to 71.7. Higher GARD values were significantly associated with improved OS in univariate (HR = 0.941, P = 0.041) and multivariable analyses (HR = 0.943, P = 0.046), while T and N stages were not. GARD demonstrated superior predictive performance at 36 months (AUC = 78.26) versus clinical variables (AUC = 71.20). Two GARD-based RT de-escalation strategies were identified, offering potential survival benefits while reducing radiation exposure.CONCLUSION GARD predicts OS and outperforms clinical variables, supporting its integration into the diagnostic workflow for personalized RT in HPV+ OPSCC.FUNDING This work was supported by the National Cancer Institute through the Cleveland Clinic/Emory ROBIN center (U54-CA274513, project 2), the European Union Horizon 2020 Framework Programme (grant/award 689715), the Italian Association for Cancer Research (AIRC project ID 23573), and the European Research Area Network ERA PerMed JTC2019/Fondazione Regionale per la Ricerca Biomedica project SuPerTreat (Supporting Personalized Treatment Decisions in Head and Neck Cancer through Big Data).
Authors
Emily Ho, Loris De Cecco, Steven A. Eschrich, Stefano Cavalieri, Geoffrey Sedor, Frank Hoebers, Ruud H. Brakenhoff, Kathrin Scheckenbach, Tito Poli, Kailin Yang, Jessica A. Scarborough, Shivani Nellore, Shauna Campbell, Neil Woody, Tim Chan, Jacob Miller, Natalie Silver, Shlomo Koyfman, James Bates, Jimmy J. Caudell, Michael W. Kattan, Lisa Licitra, Javier F. Torres-Roca, Jacob G. Scott
Abstract
Mutant KRAS has been implicated in driving a quarter of all cancer types. Although inhibition of the KRASG12C mutant protein has shown clinical promise, there is still a need for therapies that overcome resistance and target non-KRASG12C mutations. KRAS activates downstream MYC, which is also a difficult-to-drug oncoprotein. We have developed an “inverted” RNAi molecule with the passenger strand of a MYC-targeting siRNA fused to the guide strand of a KRAS-targeting siRNA. The chimeric molecule simultaneously inhibits KRAS and MYC, showing marked improvements in efficacy beyond the individual siRNA components. This effect is mediated by 5′-dT overhangs following endosomal metabolism. The synergistic RNAi activity led to a more than 10- to 40-fold improvement in inhibition of cancer viability in vitro. When conjugated to an EGFR-targeting ligand, the chimeric siRNA was delivered to and internalized by tumor cells. As compared with individual targeting siRNAs, the chimeric design resulted in considerably improved metabolic stability in tumors, enhanced silencing of both oncogenes, and reduced tumor progression in multiple cancer models. This inverted chimeric design establishes proof of concept for ligand-directed, dual silencing of KRAS and MYC in cancer and constitutes an innovative molecular strategy for cotargeting any two genes of interest, which has broad implications.
Authors
Yogitha S. Chareddy, Hayden P. Huggins, Snehasudha S. Sahoo, Lyla J. Stanland, Christina Gutierrez-Ford, Kristina M. Whately, Lincy Edatt, Salma H. Azam, Matthew C. Fleming, Jonah Im, Alessandro Porrello, Imani Simmons, Jillian L. Perry, Albert A. Bowers, Martin Egli, Chad V. Pecot
Abstract
Calciphylaxis is a rare but life-threatening disorder characterized by ectopic calcification affecting the subcutaneous tissues and blood vessels of the skin. Survival rates are less than a year after diagnosis, and yet despite the severity of the condition, the pathobiology of calciphylaxis is ill understood. Here, we created animal models of calciphylaxis that recapitulated many characteristics of the human phenotype. We demonstrate that cutaneous calcification is preceded by inflammatory cell infiltration. We show that increased local skin inflammation, regardless of the inciting cause, in the presence of hypercalcemia and hyperphosphatemia contributes to cutaneous ectopic calcification. Genetically modified rodents lacking immune activation of T and B cells or NK cells are resistant to developing cutaneous calcification. Consistent with this, administration of the immunosuppressive cyclophosphamide reduced calcific deposits, as did T cell suppression with cyclosporine. We demonstrate that IL-17 is upregulated in calcific skin and neutrophils are the predominant cell type expressing IL-17 and tissue-nonspecific alkaline phosphatase (TNAP) that are necessary for ectopic calcification. Targeting IL-17 with a monoclonal antibody or using a myeloperoxidase inhibitor to blunt neutrophil activation notably attenuated calcific deposits in vivo. Taken together, these observations provide fresh insight into the role of the immune system and the IL-17/neutrophil axis in mediating ectopic calcification in rodent models of calciphylaxis.
Authors
Bo Tao, Edward Z. Cao, James Hyun, Sivakumar Ramadoss, Juan F. Alvarez, Lianjiu Su, Qihao Sun, Zhihao Liu, Linlin Zhang, Alejandro Espinoza, Yiqian Gu, Feiyang Ma, Shen Li, Matteo Pellegrini, Arjun Deb
Abstract
The fetal liver is the primary site of hematopoietic stem cell (HSC) generation during embryonic development. However, the molecular mechanisms governing the transition of hematopoiesis from the fetal liver to the BM remain incompletely understood. Here, we identify the mammalian Polycomb Group protein Yin Yang 1 (YY1) as a key regulator of this developmental transition. Conditional deletion of Yy1 in the hematopoietic system during fetal development results in neonatal lethality and depletion of the fetal HSC pool. YY1-deficient fetal HSCs exhibit impaired migration and fail to engraft in the adult BM, thereby losing their ability to reconstitute hematopoiesis. Transcriptomic analysis reveals that Yy1 KO disrupts genetic networks controlling cell motility and adhesion in fetal hematopoietic stem and progenitor cells (HSPCs). Notably, YY1 does not directly bind the promoters of most dysregulated genes. Instead, it modulates chromatin accessibility at regulatory loci, orchestrating broader epigenetic programs essential for HSPC migration and adhesion. Together, these findings establish YY1 as a critical epigenetic regulator of fetal HSC function and provide a mechanistic framework to further decipher how temporal epigenomic configurations determine HSC fetal-to-adult transition during development.
Authors
Sahitya Saka, Zhanping Lu, Yinghua Wang, Peng Liu, Deependra K. Singh, Junki P. Lee, Carmen G. Palii, Tyler R. Alvarez, Anna L.F.V. Assumpção, Xiaona You, Jing Zhang, Marjorie Brand, Michael L. Atchison, Xuan Pan
Abstract
Selective and controlled expansion of endogenous β cells has been pursued as a potential therapy for diabetes. Ideally, such therapies would preserve feedback control of β cell proliferation to avoid excessive β cell expansion. Here, we identified a regulator of β cell proliferation whose inactivation resulted in controlled β cell expansion: the protein deacetylase sirtuin 2 (SIRT2). Sirt2 deletion in β cells of mice increased β cell proliferation during hyperglycemia with little effect under homeostatic conditions, indicating preservation of feedback control of β cell mass. SIRT2 restrains proliferation of human islet β cells, demonstrating conserved SIRT2 function. Analysis of acetylated proteins in islets treated with a SIRT2 inhibitor revealed that SIRT2 deacetylates enzymes involved in oxidative phosphorylation, dampening the adaptive increase in oxygen consumption during hyperglycemia. At the transcriptomic level, Sirt2 inactivation has context-dependent effects on β cells, with Sirt2 controlling how β cells interpret hyperglycemia as a stress. Finally, we provide proof of principle that systemic administration of a glucagon-like peptide 1–coupled (GLP1-coupled), Sirt2-targeting antisense oligonucleotide achieves β cell Sirt2 inactivation and stimulates β cell proliferation during hyperglycemia. Overall, these studies identify a therapeutic strategy for increasing β cell mass in diabetes without circumventing feedback control of β cell proliferation. Future work should test the extent to which these findings translate to human β cells from individuals with or without diabetes.
Authors
Matthew Wortham, Bastian Ramms, Chun Zeng, Jacqueline R. Benthuysen, Somesh Sai, Dennis P. Pollow, Fenfen Liu, Michael Schlichting, Austin R. Harrington, Bradley Liu, Thazha P. Prakash, Elaine C. Pirie, Han Zhu, Siyouneh Baghdasarian, Sean T. Lee, Victor A. Ruthig, Kristen L. Wells, Johan Auwerx, Orian S. Shirihai, Maike Sander
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