CYLD-TRAF6 interaction promotes ADP-heptose-induced NF-κB signaling in H. pylori infectionLim, Michelle C C; Maubach, Gunter; Naumann, Michael
doi: 10.1038/s44319-025-00480-ypmid: 40404856
The inflammatory response associated with Helicobacter pylori (H. pylori) infection causes a multitude of alterations in the gastric microenvironment, leading to the slow and steady disruption of the gastric epithelial barrier. Activation of NF-κB during H. pylori infection is crucial to this inflammatory response. Here, we show that CYLD, which interacts constitutively with TRAF6, enhances H. pylori’s ADP-heptose-induced activation of the classical NF-κB pathway in gastric epithelial cells. This activating effect of CYLD contrasts with the inhibitory effect of CYLD on receptor-mediated NF-κB activity. Mechanistically, CYLD counteracts the hydrolysis of ubiquitin chains from TRAF6 by deubiquitinylase A20 in a catalytically independent manner, thus supporting the auto-ubiquitinylation of TRAF6 upon activation of NF-κB in early H. pylori infection. In addition, the subsequent classical NF-κB-dependent de novo synthesis of A20 provides a negative feedback loop leading to shutdown not only of the classical but also of the alternative NF-κB pathway. Our findings highlight the regulatory relationship between CYLD and A20 in controlling classical as well as alternative NF-κB signaling in H. pylori infection.
Palmitoylated importin α regulates mitotic spindle orientation through interaction with NuMASutton, Patrick James; Mosqueda, Natalie; Brownlee, Christopher W
doi: 10.1038/s44319-025-00484-8pmid: 40425783
Regulation of cell division orientation is a fundamental process critical to differentiation and tissue homeostasis. Microtubules emanating from the mitotic spindle pole bind a conserved complex of proteins at the cell cortex which orients the spindle and ultimately the cell division plane. Control of spindle orientation is of particular importance in developing tissues, such as the developing brain. Misorientation of the mitotic spindle and thus subsequent division plane misalignment can contribute to improper segregation of cell fate determinants in developing neuroblasts, leading to a rare neurological disorder known as microcephaly. We demonstrate that the nuclear transport protein importin α, when palmitoylated, plays a critical role in mitotic spindle orientation through localizing factors, such as NuMA, to the cell cortex. We also observe craniofacial developmental defects in Xenopus laevis when importin α palmitoylation is abrogated, including smaller head and brains, a hallmark of spindle misorientation and microcephaly. These findings characterize not only a role for importin α in spindle orientation, but also a broader role for importin α palmitoylation which has significance for many cellular processes.
An alternative mechanism by which If1 prevents ATP hydrolysis by the ATP synthase subcomplex in S. cerevisiaeLerouley, Orane; Larrieu, Isabelle; Ducrocq, Tom Louis; Pinson, Benoît; Giraud, Marie-France; Mourier, Arnaud
doi: 10.1038/s44319-025-00430-8pmid: 40490602
The mitochondrial F1F0-ATP synthase is crucial for maintaining the ATP/ADP balance which is critical for cell metabolism, ion homeostasis and cell proliferation. This enzyme, conserved across evolution, is found in the mitochondria or chloroplasts of eukaryotic cells and the plasma membrane of bacteria. In vitro studies have shown that the mitochondrial F1F0-ATP synthase is reversible, capable of hydrolyzing instead of synthesizing ATP. In vivo, its reversibility is inhibited by the endogenous peptide If1 (Inhibitory Factor 1), which specifically prevents ATP hydrolysis in a pH-dependent manner. Despite its presumed importance, the loss of If1 in various model organisms does not cause severe phenotypes, suggesting its role may be confined to specific stress or metabolic conditions yet to be discovered. Our analyses indicate that inhibitory peptides are crucial in mitigating mitochondrial depolarizing stress under glyco-oxidative metabolic conditions. Additionally, we found that the absence of If1 destabilizes the nuclear-encoded free F1 subcomplex. This mechanism highlights the role of If1 in preventing harmful ATP wastage, offering new insights into its function under physiological and pathological conditions.
Inflammation and IL-4 regulate Parkinson’s and Crohn’s disease associated kinase LRRK2Dikovskaya, Dina; Pemberton, Rebecca; Taylor, Matthew; Tasegian, Anna; Bhattacharya, Purbasha; Zeneviciute, Karolina; Sammler, Esther M; Howden, Andrew J M; Alessi, Dario R; Swamy, Mahima
doi: 10.1038/s44319-025-00473-xpmid: 40394349
Mutations in Leucine-Rich Repeat protein Kinase 2 (LRRK2) are associated with Parkinson’s disease (PD) and Crohn’s disease (CD), but the regulation of LRRK2 during inflammation remains relatively unexplored. Here we describe the development of a flow cytometry-based assay to assess LRRK2 activity in individual cells and the generation of an EGFP-Lrrk2 knock-in reporter mouse to analyse cell-specific LRRK2 expression. Using these tools, we measured LRRK2 levels and activity in murine splenic and intestinal immune cells and in human blood. Anti-CD3 induced inflammation increases LRRK2 expression and activity in B cells and monocytes, while in mature neutrophils, inflammation stimulates activity but reduces LRRK2 expression. A kinase-activating PD-associated LRRK2-R1441C mutation exacerbates inflammation-induced activation of LRRK2 specifically in monocytes and macrophages. We identify IL-4 as a novel T-cell-derived factor that upregulates LRRK2 expression and activity in B cells, replicating inflammatory effects observed in vivo. Our findings provide valuable new insights into the regulation of the LRRK2 pathway in immune cells, crucial for understanding LRRK2 and its therapeutic potential in inflammatory diseases such as CD.
Laminin-defined mechanical status modulates retinal pigment epithelium phagocytosisKozyrina, Aleksandra N; Piskova, Teodora; Semeraro, Francesca; Doolaar, Iris C; Prapty, Taspia; Haraszti, Tamás; Hubert, Maxime; Windoffer, Reinhard; Leube, Rudolf E; Smith, Ana-Sunčana; Di Russo, Jacopo
doi: 10.1038/s44319-025-00475-9pmid: 40389756
Epithelial cells exhibit strong interconnections that are crucial for tissue mechanical properties. In homeostasis, these properties, termed mechanical homeostasis, depend on the balance between intercellular tension and extracellular matrix (ECM) adhesion forces. While age-related ECM remodeling is linked to outer retinal disease, its fundamental role in mechanical homeostasis remains unclear. In our study, we quantified changes in the mechanical state of retinal pigment epithelium (RPE), revealing a correlation with gradients of basement membrane laminins and their integrin receptors, β1 and β4. This relationship is related to regional phagocytic demand for recycling photoreceptor outer segments. Using a reductionist approach, we found that laminin 332 and laminin 511 isoforms differentially influence engagement with β1 and β4 integrins at low densities. Notably, laminin 511 enhances RPE contractility by reducing the β4 to β1 integrin engagement ratio, which subsequently diminishes phagocytic efficiency. Our findings suggest that the ECM-defined mechanical status of RPE serves as a novel parameter for visual function.