Megakaryocytes transfer mitochondria to bone marrow mesenchymal stromal cells to lower platelet activation

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Abstract

Newly produced platelets acquire a low activation state but whether the megakaryocyte plays a role in this outcome has not been fully uncovered. Mesenchymal stem cells (MSCs) were previously shown to promote platelet production and lower platelet activation. We found healthy megakaryocytes transfer mitochondria to MSCs mediated by Connexin 43 (Cx43) gap junctions on MSCs, which leads to platelets at a low energetic state with increased LYN activation, characteristic of resting platelets. On the contrary, MSCs have a limited ability to transfer mitochondria to megakaryocytes. Sickle cell disease (SCD) is characterized by hemolytic anemia and results in heightened platelet activation, contributing to numerous disease complications. Platelets in SCD mice and human patient samples had a heightened energetic state with increased glycolysis. MSC exposure to heme in SCD led to decreased Cx43 expression and a reduced ability to uptake mitochondria from megakaryocytes. This prevented LYN activation in platelets and contributed to increased platelet activation at steady state. Altogether, our findings demonstrate an effect of hemolysis in the microenvironment leading to increased platelet activation in SCD. These findings have the potential to inspire new therapeutic targets to relieve thrombosis-related complications of SCD and other hemolytic conditions.

Authors

Chengjie Gao, Yitian Dai, Paul A. Spezza, Paul Boasiako, Alice Tang, Giselle Rasquinha, Hui zhong, Bojing Shao, Yunfeng Liu, Patricia A. Shi, Cheryl A. Lobo, Xiuli An, Anqi Guo, William B. Mitchell, Deepa Manwani, Karina Yazdanbakhsh, Avital Mendelson

An inherited predisposition allele promotes gastric cancer via enhancing deubiquitination-mediated activation of epithelial-to-mesenchymal transition signaling

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Abstract

Genome-wide human genetic studies have identified inherited cis-regulatory loci variants that predispose to cancers. However, the mechanisms by which these germline variants influence cancer progression, particularly through gene expression and proteostasis control, remain unclear. By analyzing genomic data from a gastric cancer (GC) case-control study (2,117 individuals), focusing on the ubiquitin-specific protease (USP) family, we identify the single nucleotide polymorphism (SNP) rs72856331 (G>A) in the promoter region of the proto-oncogene USP47 as a putative susceptibility allele for GC (OR = 0.78, P = 0.015). Mechanistically, the risk allele G is associated with enhanced USP47 expression, mediated by altered recruitment of the transcription factor GLI3 and changes in the epigenetic status at promoter. CRISPR/Cas9-mediated single-nucleotide conversion into risk allele G results in increased GLI3 binding and subsequent USP47 upregulation. The depletion of GLI3 results in a reduction of cancer-related phenotypes, similar to those observed following USP47 knockdown. Furthermore, we identify Snai1 as a deubiquitination target of USP47, explaining USP47-dependent activation of epithelial-mesenchymal transition pathway and tumor progression. Our findings identify an important genetic predisposition that implicates the perturbation of transcription and proteostasis programs in GC, offering insights into prevention and therapeutic strategies for genetically stratified patients.

Authors

Bolin Tao, Zhenning Wang, Xuanyi Wang, Aixia Song, Jiaxian Liu, Jianan Wang, Qin Zhang, Zhaolin Chen, Zixian Wang, Wenjie Xu, Menghong Sun, Yanong Wang, Ping Zhang, Tao Xu, Gong-Hong Wei, Fei Xavier Chen, Mengyun Wang

An endothelial SOX18-mevalonate pathway axis enables repurposing of statins for infantile hemangioma

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Abstract

Infantile hemangioma (IH) is the most common tumor in children and a paradigm for pathological vasculogenesis, angiogenesis, and regression. Propranolol, the mainstay treatment, inhibits IH vessel formation via a β-adrenergic receptor independent off-target effect of its R(+) enantiomer on the endothelial SRY box transcription factor 18 (SOX18). Transcriptomic profiling of patient-derived hemangioma stem cells (HemSC) uncovered the mevalonate pathway (MVP) as a target of R(+) propranolol. Loss and gain of function of SOX18 confirmed it is both necessary and sufficient for R(+) propranolol suppression of the MVP, including regulation of sterol regulatory element binding protein 2 (SREBP2) and the rate-limiting enzyme HMG-CoA reductase (HMGCR). AThe biological relevance of the endothelial SOX18-MVP axis in IH patient tissue was demonstrated by nuclear co-localization of SOX18 and SREBP2. Functional validation in a preclinical IH xenograft model revealed that statins – competitive inhibitors of HMGCR – efficiently suppress IH vessel formation. We propose an novel endothelial SOX18-MVP-axis as a central regulator of IH pathogenesis and suggest statin repurposing to treat IH. The pleiotropic effects of R(+) propranolol and statins along the SOX18-MVP axis to disable an endothelial-specific program may have therapeutic implications for other vascular disease entities involving pathological vasculogenesis and angiogenesis.

Authors

Annegret Holm, Matthew S. Graus, Jill Wylie-Sears, Jerry Wei Heng Tan, Maya Alvarez-Harmon, Luke Borgelt, Sana Nasim, Long Chung, Ashish Jain, Mingwei Sun, Liang Sun, Pascal Brouillard, Ramrada Lekwuttikarn, Yanfei Qi, Joyce Teng, Miikka Vikkula, Harry Kozakewich, John B. Mulliken, Mathias Francois, Joyce Bischoff

Asparagine drives immune evasion in bladder cancer via RIG-I stability and type I IFN signaling

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Abstract

Tumor cells often employ many ways to restrain type I interferon signaling to evade immune surveillance. However, whether cellular amino acid metabolism regulate this process remains unclear and its effects on antitumor immunity are relatively unexplored. Here, we find that asparagine inhibits IFN-I signaling and promotes immune escape in bladder cancer. Depletion of asparagine synthetase (ASNS) strongly limits in vivo tumor growth in a CD8+ T cell-dependent manner and boosts immunotherapy efficacy. Moreover, clinically approved ASNase synergizes with anti-PD-1 therapy in suppressing tumor growth. Mechanistically, asparagine can directly bind to RIG-I and facilitate CBL-mediated RIG-I degradation, thereby suppressing IFN signaling and antitumor immune responses. Clinically, tumors with higher ASNS expression show decreased responsiveness to ICIs therapy. Together, our findings uncover asparagine as a natural metabolite to modulate RIG-I-mediated IFN-I signaling, providing the basis for developing the combinatorial use of ASNase and anti-PD-1 for bladder cancer.

Authors

Wenjie Wei, Hongzhao Li, Shuo Tian, Chi Zhang, Junxiao Liu, Wen Tao, Tianwei Cai, Yuhao Dong, Chuang Wang, Dingyi Lu, Yakun Ai, Wanlin Zhang, Hanfeng Wang, Kan Liu, Yang Fan, Yu Gao, Qingbo Huang, Xin Ma, Baojun Wang, Xu Zhang, Yan Huang

Reduced EIF6 dosage attenuates TP53 activation in models of Shwachman-Diamond syndrome

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Abstract

Shwachman-Diamond syndrome (SDS) is characterized by neutropenia, exocrine pancreatic insufficiency, and bony abnormalities with an increased risk of myeloid neoplasia. Almost all cases of SDS result from biallelic mutations in SBDS. SBDS interacts with EFL1 to displace EIF6 from the 60S ribosomal subunit. Released EIF6 permits the assembly of ribosomal large and small subunits in the cytoplasm. Decreased EIF6 levels due to haploinsufficiency or missense mutations which lead to decreased protein expression may provide a somatic genetic rescue and anti-leukemic effects. We observed accumulation of EIF6 protein in sbds knockout (KO) zebrafish models, confirmed in patient-derived tissues, and correlated with changes in ribosome proteins and TP53 pathways. The mechanism of action for this adaptive response is unknown. To address this, we generated an eif6 zebrafish KO line which do not survive past 10 days post fertilization. We also created two mutants with low Eif6 expression, 5-25% of the wildtype levels, that can survive until adulthood. We bred them with sbds-null strains and analyzed their phenotype and biochemical properties. Low Eif6 levels reduced Tp53 pathway activation but did not rescue neutropenia in Sbds-deficient zebrafish. Further studies elucidating the interplay between SBDS, EIF6, TP53, and cellular stress responses offer promising insights into SDS pathogenesis, somatic genetic rescue, and therapeutic strategies.

Authors

Usua Oyarbide, Valentino Bezzerri, Morgan Staton, Christian Boni, Arish Shah, Marco Cipolli, Eliezer Calo, Seth J. Corey

Super-enhancer-driven EFNA1 fuels tumor progression in cervical cancer via the FOSL2-Src/AKT/STAT3 axis

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Abstract

Super-enhancers (SEs) are expansive cis-regulatory elements known for amplifying oncogene expression across various cancers. However, their role in cervical cancer (CC), a remarkable global malignancy affecting women, remains underexplored. Here we applied integrated epigenomic and transcriptomic profiling to delineate the distinct SE landscape in CC by analyzing paired tumor and normal tissues. Our study identifies a tumor-specific SE at the EFNA1 locus that drives EFNA1 expression in CC. Mechanically, the EFNA1 SE region contains consensus sequences for the transcription factor FOSL2, whose knockdown markedly suppressed luciferase activity and diminished H3K27ac enrichment within the SE region. Functional analyses further underlined EFNA1’s oncogenic role in CC, linking its overexpression to poor patient outcomes. EFNA1 knockdown strikingly reduced CC cell proliferation, migration, and tumor growth. Moreover, EFNA1 cis-interacted with its receptor EphA2, leading to decreased EphA2 tyrosine phosphorylation and subsequent activation of the Src/AKT/STAT3 forward signaling pathway. Inhibition of this pathway with specific inhibitors substantially attenuated the tumorigenic capacity of EFNA1-overexpressing CC cells in both in vitro and in vivo models. Collectively, our study unveils the critical role of SEs in promoting tumor progression through the FOSL2-EFNA1-EphA2-Src/AKT/STAT3 axis, providing new prognostic and therapeutic avenues for CC patients.

Authors

Shu-Qiang Liu, Xi-Xi Cheng, Shuai He, Tao Xia, Yi-Qi Li, Wan Peng, Ya-Qing Zhou, Zi-Hao Xu, Mi-Si He, Yang Liu, Pan-Pan Wei, Song-Hua Yuan, Chang Liu, Shu-Lan Sun, Dong-Ling Zou, Min Zheng, Chun-Yan Lan, Chun-Ling Luo, Jin-Xin Bei

Aberrant ERK signaling in astrocytes impairs learning and memory in RASopathy-associated BRAF mutant mouse models

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Abstract

RAS/MAPK pathway mutations often induce RASopathies with overlapping features, such as craniofacial dysmorphology, cardiovascular defects, dermatologic abnormalities, and intellectual disabilities. Although BRAF gene mutations are associated with cardio-facio-cutaneous (CFC) syndrome and Noonan syndrome, it remains unclear how these mutations impair cognition. Here, we investigated the underlying neural mechanisms using several mouse models harboring a gain-of-function BRAF mutation (K499E) discovered in RASopathy patients. We found expressing BRAF K499E (KE) in neural stem cells under the control of a Nestin-Cre promoter (Nestin;BRAFKE/+) induced hippocampal memory deficits, but expressing it in excitatory or inhibitory neurons did not. BRAF KE expression in neural stem cells led to aberrant reactive astrogliosis, increased astrocytic Ca2+ fluctuations, and reduced hippocampal long-term depression (LTD) in mice. Consistently, 3D human cortical spheroids expressing BRAF KE also showed reactive astrogliosis. Astrocyte-specific AAV-BRAF KE delivery induced memory deficits, reactive astrogliosis, and increased astrocytic Ca2+ fluctuations. Notably, reducing ERK activity in astrocytes rescued the memory deficits and altered astrocytic Ca2+ activity of Nestin;BRAFKE/+ mice. Furthermore, reducing astrocyte Ca2+ activity rescued the spatial memory impairments of BRAF KE-expressing mice. Our results demonstrate that ERK hyperactivity contributes to astrocyte dysfunction associated with Ca2+ dysregulation, leading to the memory deficits of BRAF-associated RASopathies.

Authors

Minkyung Kang, Jihye Choi, Jeongho Han, Toshiyuki Araki, Soo-Whee Kim, Hyun-Hee Ryu, Min-Gyun Kim, Seoyeon Kim, Hanbyul Jang, Sun Yong Kim, Kyoung-Doo Hwang, Soobin Kim, Myeongjong Yoo, Jaegeon Lee, Kitae Kim, Pojeong Park, Ja Eun Choi, Dae Hee Han, Yujin Kim, Jeongyeon Kim, Sunghoe Chang, Bong-Kiun Kaang, Jung Min Ko, Keun-Ah Cheon, Joon-Yong An, Sang Jeong Kim, Hyungju Park, Benjamin G. Neel, Chul Hoon Kim, Yong-Seok Lee

KRAS Mutants Confer Platinum Resistance by Regulating ALKBH5 Post-translational Modifications in Lung Cancer

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Abstract

Constitutively active mutations of KRAS are prevalent in non-small cell lung cancer (NSCLC). However, the relationship between these mutations and resistance to platinum-based chemotherapy and the underlying mechanisms remain elusive. In this study, we demonstrated that KRAS mutants confer resistance to platinum in NSCLC. Mechanistically, KRAS mutants mediate platinum resistance in NSCLC cells by activating ERK/JNK signaling, which inhibits ALKBH5 m6A demethylase activity by regulating post-translational modifications (PTMs) of ALKBH5. Consequently, the KRAS mutant leads to a global increase in m6A methylation of mRNAs, particularly DDB2 and XPC, which are essential for nucleotide excision repair. This methylation stabilized the mRNA of these two genes, thus enhancing NSCLC cells’ ability to repair platinum-induced DNA damage and avoid apoptosis, thereby contributing to drug resistance. Furthermore, blocking KRAS-mutant-induced m6A methylation, either by overexpressing a SUMOylation-deficient mutant of ALKBH5, or by inhibiting METTL3 pharmacologically, significantly sensitizes KRAS-mutant NSCLC cells to platinum drugs in vitro and in vivo. Collectively, our study uncovers a previously unrecognized mechanism that mediates KRAS mutant-induced chemoresistance in NSCLC cells by activating DNA repair through the modulation of the ERK/JNK/ALKBH5 PTMs-induced m6A modification in DNA damage repair-related genes.

Authors

Fang Yu, Shikan Zheng, Chunjie Yu, Sanhui Gao, Zuqi Shen, Rukiye Nar, Zhexin Liu, Shuang Huang, Lizi Wu, Tongjun Gu, Zhijian Qian

Metastatic Tumor Growth in Steatotic Liver is Promoted by HAS2-Mediated Fibrotic Tumor Microenvironment

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Abstract

Steatotic liver enhances liver metastasis of colorectal cancer, but this process is not fully understood. Steatotic liver induced by a high-fat diet (HFD) increases cancer-associated fibroblast (CAF) infiltration and collagen and hyaluronic acid (HA) production. We investigated the role of HA synthase 2 (HAS2) in the fibrotic tumor microenvironment in steatotic liver using Has2ΔHSC mice, in which Has2 is deleted from hepatic stellate cells. Has2ΔHSC mice had reduced steatotoic liver-associated metastatic tumor growth of MC38 colorectal cancer cells, collagen and HA deposition, and CAF and M2 macrophage infiltration. We found low-molecular-weight HA activates yes-associated protein (YAP) in cancer cells, which then releases connective tissue growth factor to further activate CAFs for HAS2 expression. Single-cell analyses revealed a link between CAF-derived HAS2 with M2 macrophages and colorectal cancer cells through CD44; these cells associated with exhausted CD8 T cells via programmed death-ligand 1 and programmed cell death protein 1. The HA synthesis inhibitors reduced steatotic liver-associated metastasis of colorectal cancer, YAP expression, CAF and M2 macrophage infiltration. In conclusion, steatotic liver modulates a fibrotic tumor microenvironment to enhance metastatic cancer activity through a bidirectional regulation between CAFs and metastatic tumors, enhancing the metastatic potential of colorectal cancer in the liver.

Authors

Yoon Mee Yang, Jieun Kim, Zhijun Wang, Jina Kim, So Yeon Kim, Gyu Jeong Cho, Jee Hyung Lee, Sun Myoung Kim, Takashi Tsuchiya, Michitaka Matsuda, Vijay Pandyarajan, Stephen J. Pandol, Michael S. Lewis, Alexandra Gangi, Paul W. Noble, Dianhua Jiang, Akil Merchant, Edwin M. Posadas, Neil A. Bhowmick, Shelly C. Lu, Sungyong You, Alexander M. Xu, Ekihiro Seki

PGLYRP2 drives hepatocyte-intrinsic innate immunity by trapping and clearing hepatitis B virus

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Abstract

Spontaneous clearance of hepatitis B virus (HBV) is frequent in adults (95%) but rare in infants (5%), emphasizing the critical role of age-related hepatic immunocompetence. However, the underlying mechanisms of hepatocyte-specific immunosurveillance and age-dependent HBV clearance remain unclear. Here, we identified PGLYRP2 as a hepatocyte-specific pattern recognition receptor with age-dependent expression, and demonstrated that phase separation of PGLYRP2 was a critical driver of spontaneous HBV clearance in hepatocytes. Mechanistically, PGLYRP2 recognized and potentially eliminated covalently closed circular DNA (cccDNA) via phase separation, coordinated by its intrinsically disordered region and HBV DNA-binding domain (PGLYRP2IDR/209-377) in the nucleus. Additionally, PGLYRP2 suppressed HBV capsid assembly by directly interacting with the viral capsid, mediated by its PGRP domain. This interaction promoted the nucleocytoplasmic translocation of PGLYRP2 and subsequent secretion of the PGLYRP2-HBV capsid complex, thereby bolstering the hepatic antiviral response. Pathogenic variants or deletions in PGLYRP2 impaired its ability to inhibit HBV replication, highlighting its essential role in hepatocyte-intrinsic immunity. These findings suggest that targeting the PGLYRP2-mediated host-virus interaction may offer a potential therapeutic strategy for the development of anti-HBV treatments, representing a promising avenue for achieving a functional cure for HBV infection.

Authors

Ying Li, Huihui Ma, Yongjian Zhang, Tinghui He, Binyang Li, Haoran Ren, Jia Feng, Jie Sheng, Kai Li, Yu Qian, Yunfeng Wang, Haoran Zhao, Jie He, Huicheng Li, Hongjin Wu, Yuanfei Yao, Ming Shi