Cell biology
Abstract
Cells exhibit diverse sizes and shapes, tailored for functional needs of tissues. Lung alveoli are lined by large, extremely thin epithelial alveolar type-1 cells (AT1s). Their characteristic morphology is essential for lung function and must be restored after injury. The mechanisms underlying small, cuboidal alveolar type-2 cells (AT2s) differentiation into thin AT1s remain elusive. Here, we demonstrated that AT2s undergo a stepwise morphological transformation characterized by the development of a unique thick microtubule (MT) bundle organization, critical for AT1 morphology. Using AT2 cultures and in vivo genetic loss of function models, we found that MT bundling process occurs in a transitional cell state during AT2 differentiation and was regulated by the TP53/TAU signaling axis. Notably, TAU underwent a linear clustering process, forming beads-on-a-string-like pattern that preceded thick MT-bundle formation. Genetic gain or loss of function of TAU in mouse or human models, prevented the formation of thick MT-bundles, highlighting the critical role of precise TAU levels in generating ultra-thin AT1s. This defect was associated with increased tissue fibrosis following bleomycin-induced injury in vivo. GWAS analysis revealed risk variants in MAPT locus in lung diseases. Moreover, TP53 controlled TAU expression and its loss phenocopied TAU deficiency. This work revealed an unexpected role for TAU in organizing MT-bundles during AT2 differentiation.
Authors
Satoshi Konishi, Khaliun Enkhbayar, Shuyu Liu, Naoya Miyashita, Yoshihiko Kobayashi, Vera Hutchison, Ashna Sai, Pankaj Agarwal, Jonathan Witonsky, Nathan D. Jackson, Max A. Seibold, Jichao Chen, Aleksandra Tata, Purushothama Rao Tata
Abstract
Vision begins in the outer segment compartment of photoreceptor cells, which is constantly renewed through the addition of membrane material at its base and ingestion of mature membranes at its tip by the retinal pigment epithelium (RPE). The close apposition of outer segments to the RPE is believed to be critical for maintaining this renewal process. Yet, in several retinal diseases, expansion of the subretinal space separating photoreceptors from the RPE does not immediately impact photoreceptor functionality. Here, we analyzed outer segment function and renewal in the Adam9 knockout mouse characterized by a major expansion of the subretinal space. Surprisingly, photoreceptor-RPE separation affected neither the sensitivity of photoreceptor light-responses nor the normal rate of outer segment renewal in this mouse prior to the onset of photoreceptor degeneration. The latter is achieved through the formation of elongated RPE “pseudopods” extending across the enlarged subretinal space to ingest outer segment tips. This work suggests that pseudopod formation may underlie the persistence of photoreceptor function in human diseases accompanied by photoreceptor-RPE separation, such as vitelliform macular dystrophy or age-related macular degeneration associated with subretinal drusenoid deposits.
Authors
Tylor R. Lewis, Carson M. Castillo, Sebastien Phan, Camilla R. Shores, Kylie K. Hayase, Keun-Young Kim, Mark H. Ellisman, Oleg Alekseev, Marie E. Burns, Vadim Y. Arshavsky
Abstract
Chordoma are rare malignant osseous neoplasms with a striking rate of recurrence. Primary chordomas typically originate from embryonic notochord remnants, whereas recurrent chordomas usually stem from tumor cells infiltrating bone or cartilage post-surgery. Clinically, the recurrent chordomas exhibit stiffer extracellular microenvironment (ECM) than primary tumors. Intriguingly, this study identified cytoskeleton rearrangement, stress fiber reorganization, enhanced stemness, and Notch signaling activation in recurrent chordoma tissues or cell lines surviving stiff substrates, indicating the critical roles of mechanical remodeling and tumor stemness in stiffness-resistance. We propose a novel recurrence model where tumor cells experience mechanoadaptive organization to resist stiff microenvironment-induced cell death. O-GlcNAcylation of Notch1 intracellular domain (NICD1) is central to this process. Mechanistically, the stiff ECM-driven ligand-independent phosphorylation of EPHA2 sequentially activates LYN kinase, and subsequently triggers OGT activity by phosphorylating Y989 and Y418, the newly revealed critical residues for OGT glycosyltransferase activity; this induces NICD1 O-GlcNAcylation at T2063, T2090, and S2162, specifically promoting transcription of mechanical and stemness-related genes. MIR31 deletion upregulates LYN, enhancing stiffness perception and tipping the balance toward O-GlcNAc addition to NICD1, finally resulting in mechanoadaptation- and tumor stemness-driven recurrence. Consequently, MIR31 deletion is a potential biomarker for recurrence and patient stratification in Notch- or OGT-targeted therapies.
Authors
Chengjie Lian, Weiyan Peng, Peiqiang Su, Yan Ye, Jialing Liu, Dongsheng Huang, Xuejuan Sun, Yi Pu, Zhiheng Liao, Xudong Wang, Zhu Qiu, Shanshan Wu, Lei Liu
Abstract
Metastatic progression in aggressive breast cancer (BC) depends on a tightly controlled vesicular recycling network regulated by RAB11, a small guanosine triphosphate enzyme (GTPase). In a cohort of more than 1,000 patients with BC, we identified SH3BP5L as the most highly expressed guanine nucleotide exchange factor (GEF) for RAB11A. High SH3BP5L expression marked an advanced tumor stage, distant metastasis, and poor prognosis, with significant associations in human epidermal growth factor receptor 2–positive (HER2+) and triple-negative breast cancer (TNBC). Using Förster resonance energy transfer (FRET) sensors and artificial intelligence– (AI-assisted) microscopy, we showed that cargo delivery to the plasma membrane required SH3BP5L-dependent activation of RAB11A and assembly of a complex with the anterograde motor KIF5B. This trafficking governed key metastatic features of TNBC, including β1 integrin recycling and α3β1 integrin surface exposure. Inhibition of SH3BP5L or its GEF activity reduced cell spreading in zebrafish and lung metastasis in mouse models, revealing a previously unidentified driver of BC dissemination and a potential therapeutic vulnerability.
Authors
Huayi Li, Maria Chiara De Santis, Francesco A. Tucci, Daniela Tosoni, Ping Zhang, Meredith L. Jenkins, Giulia Villari, Maria Grazia Filippone, Elisa Guerrera, Simone Tealdi, Luca Gozzelino, Federico Gulluni, Lorenzo Prever, Cristina Zanini, Marco Forni, Irene Franco, Miriam Martini, John E. Burke, Guido Serini, Carlo Cosimo Campa, Salvatore Pece, Jean Piero Margaria, Emilio Hirsch
Abstract
MAP kinase kinase kinase kinase (MAP4K) family kinases are key kinases for T-cell-mediated immune responses; however, in vivo roles of MAP4K2 in immune regulation remain unclear. Using T-cell-specific Map4k2 conditional knockout (T-Map4k2 cKO) mice, single-cell RNA sequencing (scRNA-seq), and mass spectrometry analysis, we found that MAP4K2 interacted with DDX39B, induced forkhead box protein P3 (FOXP3) gene expression, and promoted Treg differentiation. Mechanistically, MAP4K2 directly phosphorylated the DEAD box protein DDX39B, leading to DDX39B nuclear translocation and subsequent Foxp3 RNA splicing. MAP4K2-induced FOXP3 mRNA levels were abolished in DDX39B knockout T cells. Furthermore, T-Map4k2 cKO mice displayed the reduction of Treg population and the sustained inflammation during remission phase of EAE autoimmune disease model. Remarkably, the anti-PD-1 immunotherapeutic effect on pancreatic cancer was significantly improved in T-Map4k2 cKO mice, Treg-specific Map4k2-deficient mice, adoptively transferred chimeric mice, or MAP4K2-inhibitor-treated mice. Consistently, scRNA-seq analysis of human pancreatic patients showed increased MAP4K2 levels in infiltrating Treg cells. Collectively, MAP4K2 promotes Treg differentiation by inducing DDX39B nuclear translocation, leading to the attenuation of antitumor immunity.
Authors
Huai-Chia Chuang, Chia-Wen Wang, Chia-Hsin Hsueh, Yu-Zhi Xiao, Ching-Yi Tsai, Pu-Ming Hsu, Evelyn L. Tan, Hsien-Yi Chiu, Tse-Hua Tan
Abstract
The PIM kinase family is critically involved in tumorigenesis, yet its role in primary T cells is understudied. We reported that PIM2, distinct from the other two isoforms, inhibits T-cell responses to alloantigen. Here, we further established PIM2 as a key negative regulator in anti-tumor immunity. Pim2 deficiency in tumor antigen-specific or polyclonal T cells enhanced their ability to control tumor growth in murine breast cancer, melanoma and leukemia models. Pim2 deficiency enhanced cytokine production and metabolic activities in tumor-infiltrating CD8 T cells. Pim2 deficiency increased TCF1 expression and memory-like phenotype in CD8 T cells from lymphoid organs. Mechanistically, PIM2 facilitated LC3 lipidation, P62 degradation and autophagic flux in T cells, leading to impaired glycolysis and effector cytokine production. Furthermore, through modulating VPRBP kinase phosphorylation, PIM2 inhibited histone methyltransferase activity of EZH2 in CD8 T cells, causing disrupted memory-like phenotype. Notably, the PIM2 inhibitor JP11646 markedly enhanced antitumor T-cell response. The immunosuppressive role of PIM2 was validated in human T cells, where inhibition of PIM2 enhanced antitumor responses in engineered human T cells including melanoma-specific TCR-T cells and CD19CAR-T cells. Collectively, PIM2 represents a promising target for improving cancer immunotherapy through enhancing effector differentiation and persistence of CD8 T cells.
Authors
Yongxia Wu, Linlu Tian, Allison Pugel, Reza Alimohammadi, Qiao Cheng, Weiguo Cui, Michael I. Nishimura, Lauren E. Ball, Chien-Wei Lin, Shikhar Mehrotra, Andrew S. Kraft, Xue-Zhong Yu
Abstract
Glioblastoma (GBM) is a highly lethal brain tumor with limited treatment options and resistance to immune checkpoint inhibitors due to its immunosuppressive tumor microenvironment (TME). Here, we identify OLIG2 as a key regulator of immune evasion in GBM stem-like cells, inhibiting CD8+ T cell-dependent antitumor immunity, while promoting pro-tumor macrophages polarization. Mechanistically, OLIG2 recruits HDAC7 to repress CXCL10 transcription, inducing STAT3 activation in tumor-associated macrophages (TAMs) and decreasing CD8+ T cell infiltration and activation. Genetic deletion of OLIG2 significantly increases CXCL10 secretion, shifting TAMs toward an anti-tumor phenotype and enhancing CD8+ T cell activities. Furthermore, upregulated OLIG2 expression is correlated to resistance to immune checkpoint inhibitors (ICIs) in GBM patients. OLIG2 inhibition by either genetic deficiency or pharmacological targeting with CT-179 sensitizes GBM tumors to anti-PD-L1 therapy, enhancing antitumor immune responses and prolonging survival. Our findings reveal OLIG2+ glioma stem-like cells as critical mediators of immune evasion and identify the OLIG2/HDAC7/CXCL10 axis as a potential therapeutic target to enhance immune checkpoint inhibitors efficacy and to improve immunotherapy outcomes in aggressive GBM.
Authors
Xinchun Zhang, Jinjiang Xue, Cunyan Zhao, Chenqiuyue Zeng, Jiacheng Zhong, Gangfeng Yu, Xi Yang, Yao Ling, Dazhen Li, Jiaxiao Yang, Yun Xiu, Hongda Li, Shiyuan Hong, Liangjun Qiao, Song Chen, Q. Richard Lu, Yaqi Deng, Zhaohua Tang, Fanghui Lu
Abstract
Transitions of cancer cells between distinct cell states, which are typically driven by transcription reprogramming, fuel tumor plasticity, metastasis, and therapeutic resistance. Whether the transitions between cell states can be therapeutically targeted remains unknown. Here, using the epithelial-to-mesenchymal transition (EMT) as a model, we show that the transcription reprogramming during a cell-state transition induces genomic instability through R-loops and transcription-replication conflicts, and the cell-state transition cannot occur without the ATR kinase, a key regulator of the replication stress response. ATR inhibition during EMT not only increases transcription- and replication-dependent genomic instability but also disrupts transcription reprogramming. Unexpectedly, ATR inhibition elevates R-loop-associated DNA damage at the SNAI1 gene, a key driver of the transcription reprogramming during EMT, triggering ATM- and Polycomb-mediated transcription repression of SNAI1. Beyond SNAI1, ATR also suppresses R-loops and antagonizes repressive chromatin at a subset of EMT genes. Importantly, inhibition of ATR in tumors undergoing EMT reduces tumor growth and metastasis, suggesting that ATR inhibition eliminates cancer cells in transition. Thus, during EMT, ATR not only protects genome integrity but also enables transcription reprogramming, revealing that ATR is a safeguard of cell-state transitions and a target to suppress tumor plasticity.
Authors
Parasvi S Patel, Jacob P. Matson, Xiaojuan Ran, Marcello Stanzione, Ajinkya S. Kawale, Mingchao Wang, Sneha Saxena, Conrad Sander, Jacquelyn Curtis, Jessica L. Hopkins, Edmond Wong, Ryan B. Corcoran, Daniel A. Haber, Nicholas J. Dyson, Shyamala Maheswaran, Lee Zou
Abstract
Authors
Justin T. Gumas, Megumi Shigematsu, Karin E. Borgmann-Winter, Chang-Gyu Hahn, Yohei Kirino
Abstract
Protectin DX (PDX) is a member of the superfamily of specialized proresolving mediators and exerts anti-inflammatory actions in animal models; however, its signaling mechanism remains unclear. Here, we demonstrate the analgesic actions of PDX in a mouse model of tibial fracture–induced postoperative pain (fPOP). Intravenous early- and late-phase treatment of PDX (100 ng/mouse) effectively alleviated fPOP. Compared with protectin D1 (PD1)/neuroprotectin D1, DHA, steroids, and meloxicam, PDX provided superior pain relief. While dexamethasone and meloxicam prolonged fPOP, PDX shortened the pain duration. The analgesic effects of PDX were abrogated in Gpr37−/− mice, which displayed deficits in fPOP resolution. PDX was shown to bind GPR37 and induce calcium responses in peritoneal macrophages. LC-MS/MS–based lipidomic analysis revealed that endogenous PDX levels were approximately 10-fold higher than those of PD1 in muscle at the fracture site. PDX promoted macrophage polarization via GPR37-dependent phagocytosis and efferocytosis through calcium signaling in vitro, and it further enhanced macrophage viability and efferocytosis in vivo via GPR37. Finally, PDX rapidly modulated nociceptor neuron responses by suppressing C-fiber–induced muscle reflex in vivo and calcium responses in DRG neurons ex vivo and by reducing TRPA1/TRPV1-induced acute pain and neurogenic inflammation in vivo. Our findings highlight multiple benefits of PDX to manage postoperative pain and promote perioperative recovery.
Authors
Yize Li, Sangsu Bang, Jasmine Ji, Jing Xu, Min Lee, Sharat Chandra, Charles N. Serhan, Ru-Rong Ji
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ISSN: 0021-9738 (print), 1558-8238 (online)