Cell Discovery最新文献

A hallmark of aging is chronic systemic inflammation, which is exacerbated by the hypersecretory aging phenotype known as the senescence-associated secretory phenotype (SASP). How the SASP is initiated to accelerate tissue inflammation and aging is an outstanding question in aging biology. Here, we showed that phosphorylation of the Mediator subunit MED15 at T603 is able to control the SASP and aging. Transforming growth factor-β selectively induces CDK1-mediated MED15 T603 phosphorylation to control SASP gene expression. The MED15 T603 dephosphorylated mutant (T603A) inhibits the SASP and cell senescence, whereas the T603 phosphorylation-mimicking mutant (T603D) has the opposite effect. Mechanistically, forkhead box protein A1 preferentially binds to unphosphorylated but not phosphorylated MED15 at T603 to suppress SASP gene expression. Notably, aging mice harboring dephosphorylated mutation in this phosphosite exhibit improved learning and memory through the attenuation of the SASP across tissues. Overall, our study indicates that MED15 T603 phosphorylation serves as a control switch for SASP production, which underlies tissue aging and cognitive decline and provides a novel target for age-related pathogenesis.

The liver is a major target organ for breast cancer metastasis, while the regulatory mechanism of liver colonization by breast cancer remains largely unclear. Neutrophils are known to play important roles in metastatic colonization of cancer cells by the formation of neutrophil extracellular traps (NETs). Here we show the role and mechanism of a subpopulation of Kupffer cells (KCs), the liver resident macrophages, in mediating tumoral induction of NETs and liver metastasis. NETs are activated more abundantly in liver metastases of breast cancer, as compared to metastases to other organs and primary tumors. Liver-tropic tumor cells induce CD62L-expressing KCs by a secretory protein DMBT1, and CD62L⁺ KCs activate neutrophils for NETosis via the chemokine CCL8. Inhibition of CCL8 or its receptor on neutrophils, CCR1, impairs NETosis and metastasis. In addition, we identified a KC membrane protein MUC1 that binds to DMBT1 and subsequently activates NF-κB signaling in KCs, leading to CCL8 and CD62L expression. KCs with MUC1 inhibition effectively suppress liver metastasis. Furthermore, a DMBT1 neutralizing antibody was developed with the promise to inhibit tumor-KC interaction and treat metastatic cancer. In conclusion, our work reveals a KC subset that accounts for the liver tropism of breast cancer cells and NETs, and provides potential strategies in metastasis treatment.

Cancer cells can be induced to dormancy initially by specific cancer therapies, but can be reactivated for subsequent relapse as therapy-resistant cancer cells. Although the treatment-induced dormancy-to-reactivation switch is an important process in tumour spread and recurrence, little is known about the underlying molecular mechanisms, particularly the metabolic underpinnings. In this study, we demonstrated that the tryptophan catabolism-related tryptophan 2,3-dioxygenase (TDO2) -kynurenine (Kyn) -aryl hydrocarbon receptor (AhR) signalling axis was responsible for both sustaining the survival of dormant prostate cancer cells induced by androgen deprivation therapy (ADT) and promoting the reactivation of dormant cells and their recurrent outgrowth, which facilitated the development of therapeutic resistance by allowing the dormancy-to-reactivation switch. Mechanistically, we found that ADT upregulated the expression of TDO2 to produce Kyn, which activated AhR and maintained the survival of ADT-induced dormant cells. Interestingly, the switch of transcription factors from the androgen receptor (AR) to the glucocorticoid receptor (GR) modulated the persistent expression of TDO2 and promoted the reactivation of dormant cells through the same TDO2-Kyn-AhR signalling axis. Additionally, tumour recurrence following ADT was delayed by pharmacological suppression of TDO2-Kyn-AhR signalling with a TDO2 inhibitor or an AhR inhibitor. In summary, we describe a signalling circuit mediated by tryptophan metabolism for regulating tumour cell dormancy and recurrence and propose TDO2 as a new target for the treatment of androgen-sensitive prostate cancer patients in combination with ADT.

Cyclic nucleotide-gated ion channels (CNGCs) in plants mediate Ca²⁺ influx in response to environmental changes. Among numerous plant CNGCs, Medicago truncatula CNGC15a/b/c (MtCNGC15) is localized to the nuclear envelope. The opening and closing cycle of MtCNGC15 is tightly associated with the Ca²⁺ oscillation in symbiosis. However, the molecular mechanism underlying MtCNGC15 activity regulation remains unclear. In this study, we present the structures of MtCNGC15 in its apo form and in the presence of CaM. The apo MtCNGC15b exhibits a flexible cytoplasmic domain (CPD), whereas binding of the MtCaM inhibits Ca²⁺ currents and stabilizes the highly dynamic CPD. Furthermore, the activity of MtCNGC15b seems to be independent of cGMP. The hypothetical binding pocket for cGMP is occupied by an arginine residue. These findings elucidate the structural basis for the activity regulation of nuclear localized MtCNGC15.

Human glucose-6-phosphatase catalytic subunit 1 (hG6PC1) is a key enzyme in glucose metabolism, governing the final common step of gluconeogenesis and glycogenolysis, and directly regulating energy homeostasis. Aberrant mutations in G6PC1 directly cause glycogen storage disease type 1a, which is characterized by chronic hypoglycemia and glycogen accumulation. Additionally, abnormal G6PC1 function leads to increased fasting blood glucose. Consequently, it is a critical target for treating glucose metabolism disorders. In this study, we determine the cryo-EM structures of G6PC1 in both the partially open and fully open states, in either the apo form or in complex with the substrates G6P or F6P and the product phosphate. These structures offer distinct insights into the mechanism of hydrolysis and induced-fit, providing a structural foundation for the diagnostic analysis of disease-causing mutations in G6PC1. Moreover, we propose a potential mechanism by which phosphatidylserine regulates G6PC1 activity, providing a novel perspective on its role and implications.

Mushroom's specialized secondary metabolites possess important pharmacological activities, but their biosynthetic pathway elucidation is extremely challenging, not to mention reprogramming of their biosynthetic networks to target metabolites. By taking Ganoderma lucidum, a famous traditional medicinal mushroom, as a lead example, here we decoded the biosynthetic networks of type II ganoderic acids (TIIGAs), a group of its main bioactive metabolites by studying the coordinated gene expression in G. lucidum, identifying endogenous or heterologous enzymes capable of C22 hydroxylation, configuration conversion of C3 hydroxyl group, and acetylation on C3, C15 and C22 hydroxyl groups. Notably, we revealed the catalytic mechanism of the C22 hydroxylase CYP512W6, and an unexpected bifunctional acetyltransferase GlAT that is required to transfer acetyl groups to C15 and C22. Using a fluorescence-guided integration method, we achieved efficient biosynthesis of significant TIIGAs applicable to industrial fermentation. After introducing all the identified enzymes to baker's yeast, we observed that biosynthesis of downstream TIIGAs was severely impeded, and dredged the metabolic block by temporally regulating the expression of acetyltransferases. By reprogramming of the biosynthetic networks of TIIGAs, we were able to produce over 30 TIIGAs, exhibiting 1-4 orders of magnitude higher titers or efficiencies than those from farmed mushrooms. The work enables the access to valuable TIIGAs, facilitates their widespread application, and sheds light on research of other mushroom products.

Colorectal cancer (CRC), including both microsatellite instability (MSI) and microsatellite stability (MSS) subtypes, frequently exhibits intrinsic resistance to immunotherapy. However, the spatial tumor microenvironment (TME) and its role in distinguishing immunotherapy responders from non-responders remain poorly understood. In this study, spatial multiomics, including imaging mass cytometry (n = 50 in-house), spatial proteomics (n = 50 in-house), and spatial transcriptomics (n = 9 in-house), were employed to elucidate the spatial TME of metastatic CRC (mCRC) patients receiving immunotherapy. These methodologies were integrated with single-cell RNA sequencing (scRNA-seq), bulk RNA-seq, and bulk proteomics for comprehensive analysis and validation. A spatial immune atlas containing 314,774 cells was constructed. We found that C1QC⁺ resident tissue macrophages (RTMs) were more abundant in responders regardless of microsatellite status. Co-localization of C1QC⁺ RTMs with CD4⁺ T cells was observed in responders, and MHC-II expression facilitated their interaction. In contrast, cancer-associated fibroblasts inhibited this interaction in non-responders. Moreover, whole genome screening identified key genes involved in antigen presentation in C1QC⁺ RTMs. Hence, our study highlights the importance of spatial immune mapping in revealing the complex spatial topology of CRC and corresponding immunotherapy response.