Cell biology
Abstract
Authors
Deborah Moser, Alexandra N. Birtasu, Lilli Skaer, Pauline Roth, Lisa Rehm, Mike Wenzel, Julia Bein, Jens Köllermann, Mbuso S. Mantanya, Felix K.H. Chun, Margot P. Scheffer, Achilleas S. Frangakis
Abstract
Neutrophils play a pivotal role in the progression of metabolic dysfunction–associated steatohepatitis (MASH) by mediating inflammatory responses. However, the heterogeneity of neutrophil subsets in MASH and their specific contributions to disease progression remain unclear. In this study, analysis of liver biopsies from 265 patients revealed a strong association between elevated neutrophil counts and MASH severity, particularly fibrosis. Five distinct neutrophil subsets were identified in human liver tissue, with PAD4+ neutrophils serving as key drivers in MASH progression. Mechanistically, PAD4+ neutrophils generate neutrophil extracellular traps (NETs) and activate hepatic stellate cells via the TAOK1-dependent MAPK signaling pathway. Inhibition of PAD4+ neutrophils in vivo attenuated the progression of liver fibrosis without exacerbating liver injury. Collectively, these findings elucidate the pivotal involvement of PAD4+ neutrophils in MASH progression and identify them as promising therapeutic targets for mitigating fibrosis and inflammation.
Authors
Jiajia Shen, Shanshan Huang, Yaohui Wang, Qingyuan Wang, Shibo Lin, Wei Guan, Yingyun Gong, Yiming Si, Ming Zhao, Hongwen Zhou, Hui Liang
Abstract
Cardiomyocyte growth is tightly controlled by multiple signaling pathways. Identification of master kinases in this process is essential in exploring potential targets for the treatment of pathological cardiac hypertrophy and heart failure. Here we identified the mTOR-independent activation of ribosomal protein S6 kinase b1 (Rps6kb1/S6K1) during cardiomyocyte growth. By utilizing phosphoproteomics in primary neonatal rat ventricular myocytes (NRVMs), we revealed Rps6kb1 as one of most activated kinases under growth stimulation. We further demonstrated the role of Rps6kb1 phosphorylation in pathological cardiac hypertrophy and heart failure. We showed that the phosphorylation of multiple sites at Rps6kb1, including T367 in the kinase domain and S418/T421/S424 in the C-terminal domain, is not directly regulated by the activity of mTOR, rather coupled with the activation of the MEK1-ERK axis. In mice, cardiomyocyte-specific deletion of Rps6kb1 significantly inhibited both constitutively active ERK- and pressure overload-induced cardiac hypertrophy. In contrast, cardiomyocyte-specific overexpression of wild-type Rps6kb1, rather than the phosphorylation-defective mutant, elevated cardiac hypertrophy and augmented pressure overload-induced heart failure. In conclusion, our findings reveal that the MEK-ERK axis primes Rps6kb1 activation through phosphorylation of two separate domains of Rps6kb1, which may play an essential role in cardiac hypertrophy and heart failure under hemodynamic stress.
Authors
Chao Li, Pengfei Zhang, Kai Zhang, Jane A. Cook, Weidan Song, Megan Virostek, Lily A. Slotabec, Nadiyeh Rouhi, Mohammed Hazari, Michael I. Adenawoola, Xiaofei Liu, Hao Zhang, Guangyu Zhang, Erica L Niewold, Qinfeng Li, Yong Fang, Waleed M. Elhelaly, Xue-Nan Sun, Xuejiang Guo, Andrew Lemoff, Yingfeng Deng, Thomas G. Gillette, Ji Li, Philipp E. Scherer, Zhao V. Wang
Abstract
Sustained injury to renal tubular epithelial cells (TECs), driven by excessive autophagy, is a critical mechanism underlying kidney fibrosis. Our previous work identified JLP—a TEC-expressed scaffolding protein—as an endogenous anti-fibrotic factor that counteracts TGF-β1–induced autophagy and fibrogenesis. However, the mechanism underlying JLP downregulation in renal fibrosis remains unclear. Here, we delineated a TGF-β1/LEF1/β-catenin/JLP axis that governed TEC autophagy through a dichotomous regulatory circuit. Under physiological conditions, low levels of β-catenin and LEF1 with minimal nuclear localization permit normal JLP expression, which in turn maintains autophagy in check. In contrast, during renal injury, TGF-β1 promoted the expression and nuclear translocation of β-catenin and LEF1, which together suppressed JLP transcription. This loss of JLP-mediated inhibition led to unchecked autophagy and exacerbated fibrotic damage. Analyses of kidney tissues from patients with CKD, murine fibrotic kidneys, and cultured HK-2 cells confirmed consistent JLP downregulation accompanied by upregulation and nuclear accumulation of LEF1 and β-catenin. Therapeutic intervention using the β-catenin/LEF1 inhibitor iCRT3 or LEF1-targeted silencing in murine fibrosis models restored JLP expression, attenuated TEC autophagy, and ameliorated renal fibrosis. These findings revealed an autoregulatory circuit controlling TEC autophagy and fibrogenesis, and supported LEF1 and β-catenin as potential therapeutic targets in CKD.
Authors
Chen Li, Meng Zhang, Maoqing Tian, Zeyu Tang, Yuying Hu, Yuyu Long, Xiaofei Wang, Liwen Qiao, Jiefei Zeng, Yujuan Wang, Xinghua Chen, Cheng Chen, Xiaoyan Li, Lu Zhang, Huiming Wang
Abstract
This investigation leverages single-cell RNA sequencing (scRNA-Seq) to delineate the contributions of muscle-resident Schwann cells to neuromuscular junction (NMJ) remodeling by comparing a model of stable innervation with models of reinnervation following partial or complete denervation. The study discovered multiple distinct Schwann cell subtypes, including a novel terminal Schwann cell (tSC) subtype integral to the denervation-reinnervation cycle, identified by a transcriptomic signature indicative of cell migration and polarization. The data also characterizes three myelin Schwann cell subtypes, which are distinguished based on enrichment of genes associated with myelin production, mesenchymal differentiation or collagen synthesis. Importantly, SPP1 signaling emerges as a pivotal regulator of NMJ dynamics, promoting Schwann cell proliferation and muscle reinnervation across nerve injury models. These findings advance our understanding of NMJ maintenance and regeneration and underscore the therapeutic potential of targeting specific molecular pathways to treat neuromuscular and neurodegenerative disorders.
Authors
Steve D. Guzman, Ahmad Abu-Mahfouz, Carol S. Davis, Lloyd P. Ruiz, Peter C.D. Macpherson, Susan V. Brooks
Abstract
C-type natriuretic peptide (CNP) is known to promote chondrocyte proliferation and bone formation; however, CNP’s extremely short half-life necessitates continuous intravascular administration to achieve bone-lengthening effects. Vosoritide, a CNP analog designed for resistance to neutral endopeptidase, allows for once daily administration. Nonetheless, it distributes systemically rather than localizing to target tissues, which may result in adverse effects such as hypotension. To enhance local drug delivery and therapeutic efficacy, we developed a novel synthetic protein by fusing a collagen-binding domain (CBD) to CNP, termed CBD-CNP. This fusion protein exhibited stability under heat conditions and retained the collagen-binding ability and bioactivity as CNP. CBD-CNP localized to articular cartilage in fetal murine tibiae and promoted bone elongation. Spatial transcriptomic analysis revealed that the upregulation of chondromodulin expression may contribute to its therapeutic effects. Treatment of CBD-CNP mixed with collagen powder to a fracture site of a mouse model increased bone mineral content and bone volume rather than CNP-22. Intra-articular injection of CBD-CNP to a mouse model of knee osteoarthritis suppressed subchondral bone thickening. By addressing the limitations of CNP’s rapid degeneration, CBD-CNP leverages its collagen-binding capacity to achieve targeted, sustained delivery in collagen-rich tissues, offering a promising strategy for enhancing chondrogenesis and osteogenesis.
Authors
Kenta Hirai, Kenta Sawamura, Ryusaku Esaki, Ryusuke Sawada, Yuka Okusha, Eriko Aoyama, Hiroki Saito, Kentaro Uchida, Takehiko Mima, Satoshi Kubota, Hirokazu Tsukahara, Shiro Imagama, Masaki Matsushita, Osamu Matsushita, Yasuyuki Hosono
Abstract
The transcription factor IKAROS, encoded by IKZF1, is crucial for lymphocyte development and differentiation. Germline heterozygous IKZF1 mutations cause B cell immunodeficiency, but also affect T cells. Patients with IKZF1 haploinsufficiency (HI) or dimerization-defective (DD) variants show reduced naive and increased memory T cells, while dominant-negative (DN) mutations result in the opposite phenotype. Gain-of-function patients display variable patterns. To investigate IKAROS’s role in shaping the human naive/memory T cell phenotype, we performed IKAROS immunomodulation and knockdown experiments and analyzed early T cell development in an artificial thymic organoid (ATO) system using CD34+ cells from patients with representative IKZF1 variants. IKAROS inhibition by lenalidomide or silencing by small hairpin RNA directly altered expression of HNRNPLL, the master regulator of CD45 isoform splicing that defines CD45RA+/naive and CD45RO+/memory phenotypes. In the ATO system, IKAROS-DN precursor cells were blocked at the CD4–CD8–/double-negative stage and retained a CD45RA+ phenotype, whereas IKAROS-HI cells inefficiently reached the CD4+CD8+/double-positive stage and partially transitioned from CD45RA to CD45RO. Analysis of public gene expression data showed high HNRNPLL expression in double-positive thymic cells, beyond the stages affected by IKZF1 DN and HI mutations. Collectively, these findings indicate that IKAROS regulates early and late T cell development by mechanisms, including HNRNPLL modulation.
Authors
Jennifer Stoddard, Hye Sun Kuehn, Ravichandra Tagirasa, Marita Bosticardo, Francesca Pala, Julie E. Niemela, Agustin A. Gil Silva, Kayla Amini, Eduardo Anaya, Mario Framil Seoane, Carolina Bouso, Dimana Dimitrova, Jennifer A. Kanakry, Laia Alsina, Matias Oleastro, Steven M. Holland, Thomas A. Fleisher, Richard L. Wasserman, Luigi D. Notarangelo, Sergio D. Rosenzweig
Abstract
Pulmonary fibrosis (PF) is a pathology associated with interstitial lung diseases (ILDs), including idiopathic pulmonary fibrosis (IPF). Fibrosis promotes continual secretion of extracellular matrix (ECM), producing nonfunctional scar tissue and causing organ failure. This study investigated the tyrosine kinase receptor Ephrin type-B receptor 4 (EphB4) as a mediator of PF. To this end, we generated mice with conditional Col1a2-driven deletion of Ephb4 and used a preclinical mouse model of PF, total and single nuclei RNA (snRNA) sequencing, NanoString, previously published single-cell data, computational analysis, and functional assays of mouse and human healthy control and IPF lung fibroblasts. Col1a2-CreERT–driven Ephb4 deletion, or EphB4 inhibition via NVP-BHG712, markedly protected against bleomycin-induced PF. Total RNA-Seq of fibroblasts isolated from Ephb4-deficient fibrotic mouse lungs exhibited reduced expression of ECM, ER Cargo, and protein trafficking–related genes. NVP-BHG712 reduced expression of these identified genes in mouse lung fibroblasts under fibrotic conditions in vitro. snRNA-Seq of mouse lungs treated with NVP-BHG712 identified transcriptomic changes of ECM genes in specific fibroblast subpopulations. RNA-Seq, computational, and functional assays using mouse and human IPF fibroblasts identified elastin as a key mediator involved in EphB4 signaling. Combined, our data show that EphB4 is a crucial mediator of PF.
Authors
Brian Wu, Starlee S. Lively, Shabana Vohra, Noah Fine, Chiara Pastrello, Anca Maglaviceanu, Osvaldo Espin-Garcia, Evan Pollock-Tahiri, Sayaka Nakamura, Paramvir Kaur, Keemo Delos Santos, Jason S. Rockel, Pratibha Potla, Himanshi Gupta, Poulami Datta, Laura Tang, Jacob Kwon, Akihiro Nakamura, Matthew B. Buechler, Rajiv Gandhi, Jiangping Wu, Boris Hinz, Igor Jurisica, Mohit Kapoor
Abstract
Induction of heme oxygenase-1 (HO-1/Hmox1) is broadly considered cytoprotective, but the role of colonic epithelial HO-1 in colitis-associated tumorigenesis is poorly defined. HO-1 catabolizes heme, releasing ferrous iron, a key driver of oxidative stress and lipid peroxidation. We observed that colonic epithelial HO-1 is induced during colitis and tumorigenesis. We also found that HO-1 is upregulated in ferroptosis-inducing conditions in murine and human colonic epithelial organoids, and correlated with lipid peroxidation and ferroptosis markers in colonic tumors. In colonic epithelial organoids exposed to heme, deletion of Hmox1 amplified a compensatory oxidative stress and detoxification transcriptional program, likely reflecting unresolved oxidative and non-oxidative toxicity from heme. In vivo, epithelial HO-1 deficient mice developed significantly fewer and smaller tumors compared to littermate controls in a colitis-associated tumorigenesis model, despite similar inflammatory injury. Tumors from knockout mice exhibited reduced iron levels, decreased lipid peroxidation, lower oxidative DNA damage, and decreased proliferation. Single-cell RNA sequencing of tumor epithelial cells revealed a shift from a proliferative to a stress-adaptive program with loss of HO-1. These findings identify epithelial HO-1 as a context-dependent regulator of tumorigenesis: protective against acute heme toxicity, but promoting iron-dependent oxidative damage and proliferation in the setting of chronic inflammation.
Authors
Rosemary C. Callahan, Jillian C. Curry, Geetha Bhagavatula, Alyse W. Staley, Rachel E.M. Schaefer, Faiz Minhajuddin, Liheng Zhou, Rane M. Neuhart, Shaikh M. Atif, David J. Orlicky, Ian M. Cartwright, Mark E. Gerich, Calen A. Steiner, Arianne L. Theiss, Caroline H.T. Hall, Sean P. Colgan, Joseph C. Onyiah
Abstract
Fusion-positive rhabdomyosarcoma (FP-RMS), driven by PAX-FOXO1, represents the subtype of RMS with the poorest prognosis. However, the oncogenic mechanisms and therapeutic strategies of PAX-FOXO1 remain incompletely understood. Here, we discovered that N-Myc, in addition to being a classic downstream target of PAX-FOXO1, can also activate its expression and form a transcriptional complex with PAX-FOXO1, thereby markedly amplifying oncogenic signaling. The reciprocal transcriptional activation of PAX3-FOXO1 and N-Myc is critical for FP-RMS malignancy. We further identified YOD1 as a deubiquitinating enzyme (DUB) that stabilizes both PAX-FOXO1 and N-Myc. Knocking down YOD1 or inhibiting it by G5 could suppress FP-RMS growth both in vitro and in vivo, through promoting the degradation of both PAX-FOXO1 and N-Myc. Collectively, our results identify that YOD1 promotes RMS progression by regulating the PAX3-FOXO1-N-Myc positive feedback loop, and highlight YOD1 inhibition as a promising therapeutic strategy that concurrently reduces the levels of both oncogenic proteins.
Authors
Wenwen Ying, Jiayi Yu, Xiaomin Wang, Jiayi Liu, Boyu Deng, Xuejing Shao, Jinhu Wang, Ting Tao, Ji Cao, Qiaojun He, Bo Yang, Yifan Chen, Meidan Ying
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