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A recent large genome-wide association study has identified EGFR (encoding the epidermal growth factor EGFR) as a new genetic risk factor for late-onset AD. SHIP2, encoded by INPPL1 , is taking part in the signalling and interactome of several growth factor receptors, such as the EGFR. While INPPL1 has been identified as one of the most significant genes whose RNA expression correlates with cognitive decline, the potential alteration of SHIP2 expression and localization during the progression of AD remains largely unknown. Here we report that gene expression of both EGFR and INPPL1 was upregulated in AD brains. SHIP2 immunoreactivity was predominantly detected in plaque-associated astrocytes and dystrophic neurites and its increase was correlated with amyloid load in the brain of human AD and of 5xFAD transgenic mouse model of AD. While mRNA of INPPL1 was increased in AD, SHIP2 protein undergoes a significant solubility change being depleted from the soluble fraction of AD brain homogenates and co-enriched with EGFR in the insoluble fraction. Using FRET-based flow cytometry biosensor assay for tau-tau interaction, overexpression of SHIP2 significantly increased the FRET signal while siRNA-mediated downexpression of SHIP2 significantly decreased FRET signal. Genetic association analyses suggest that some variants in INPPL1 locus are associated with the level of CSF pTau. Our data support the hypothesis that SHIP2 is an intermediate key player of EGFR and AD pathology linking amyloid and tau pathologies in human AD.

Current therapeutic approaches for chronic lymphocytic leukemia (CLL) focus on the suppression of oncogenic kinase signaling. Here, we test the hypothesis that targeted hyperactivation of the phosphatidylinositol-3-phosphate/AKT (PI3K/AKT)-signaling pathway may be leveraged to trigger CLL cell death. Though counterintuitive, our data show that genetic hyperactivation of PI3K/AKT-signaling or blocking the activity of the inhibitory phosphatase SH2-containing-inositol-5′-phosphatase-1 (SHIP1) induces acute cell death in CLL cells. Our mechanistic studies reveal that increased AKT activity upon inhibition of SHIP1 leads to increased mitochondrial respiration and causes excessive accumulation of reactive oxygen species (ROS), resulting in cell death in CLL with immunogenic features. Our results demonstrate that CLL cells critically depend on mechanisms to fine-tune PI3K/AKT activity, allowing sustained proliferation and survival but avoid ROS-induced cell death and suggest transient SHIP1-inhibition as an unexpectedly promising concept for CLL therapy. Current therapeutic approaches in chronic lymphocytic leukemia (CLL) focus on the suppression of PI3K/AKT signaling. Here, the authors show that CLL cells are vulnerable to hyperactivation of the PI3K/AKT signaling pathway and suggest this as a promising concept for CLL therapy.

Alzheimer's disease (AD) remains a devastating neurodegenerative disorder with complex pathophysiology, necessitating innovative therapeutic strategies. Among the emerging targets in AD research, INPP5D, a gene that encodes the SHIP1 phosphatase, stands out as a critical regulator of microglial function and a promising avenue for intervention. Microglia, the brain's resident immune cells, play a dual role in neuroprotection and neurodegeneration, contingent on various activation states. Recent findings by Oblak et al. have illuminated INPP5D's central role in maintaining microglial homeostasis, positioning it as a key molecular regulator influencing the balance between beneficial and detrimental microglial responses. SHIP1 exerts its effects as a negative regulator of intracellular signaling cascades, which in turn govern microglial processes such as phagocytosis, inflammatory cytokine release, and synaptic pruning. Dysregulation of these pathways has been linked to exacerbated neuroinflammation and impaired clearance of amyloid-beta and other pathological substrates in AD. Leveraging insights from high-throughput assays, advanced bioinformatics, and in vivo models, Oblak et al. have elucidated the mechanistic underpinnings of SHIP1's influence on microglial activity and its downstream impact on neuronal health. These studies also underscore the potential of targeting SHIP1 to recalibrate microglial phenotypes, offering a novel therapeutic strategy for slowing or preventing AD progression. In this presentation, we will discuss how the integration of functional genomics, structural biology, and pharmacological screening within the TREAT-AD consortium has advanced our understanding of INPP5D/SHIP1. Focus will be placed on the discovery and characterization of small molecules that modulate SHIP1 activity and siRNAs that downregulate INPP5D expression. These innovative tools not only validate the therapeutic potential of INPP5D/SHIP1 but also pave the way for combination therapies and precision medicine approaches tailored to individual patients. The session aims to catalyze collaboration by presenting INPP5D/SHIP1 research as a cornerstone of TREAT-AD's mission to accelerate the discovery and development of AD therapies.

Apical-basal polarization is essential for epithelial tissue formation, segregating cortical domains to perform distinct physiological functions. Cortical lipid asymmetry has emerged as a determinant of cell polarization. We report a network of phosphatidylinositol phosphate (PIP)-modifying enzymes, some of which are transcriptionally induced upon embedding epithelial cells in extracellular matrix, and that are essential for apical-basal polarization. Unexpectedly, we find that PI(3,4)P localization and function is distinct from the basolateral determinant PI(3,4,5)P . PI(3,4)P localizes to the apical surface, and Rab11a-positive apical recycling endosomes. PI(3,4)P is produced by the 5-phosphatase SHIP1 and Class-II PI3-Kinases to recruit the endocytic regulatory protein SNX9 to basolateral domains that are being remodeled into apical surfaces. Perturbing PI(3,4)P levels results in defective polarization through subcortical retention of apically destined vesicles at apical membrane initiation sites. We conclude that PI(3,4)P is a determinant of apical membrane identity.

ObjectivesB10 and B10pro cells suppress immune responses via secreting interleukin (IL)-10. However, their regulators and underlying mechanisms, especially in human autoimmune diseases, are elusive. This study aimed to address these questions in rheumatoid arthritis (RA), one of the most common highly disabling autoimmune diseases.MethodsThe frequencies and functions of B10 and B10pro cells in healthy individuals and patients with RA were first analysed. The effects of proinflammatory cytokines, particularly tumour necrosis factor (TNF)-α on the quantity, stability and pathogenic phenotype of these cells, were then assessed in patients with RA before and after anti-TNF therapy. The underlying mechanisms were further investigated by scRNA-seq database reanalysis, transcriptome sequencing, TNF-α−/− and B cell-specific SHIP-1−/− mouse disease model studies.ResultsTNF-α was a key determinant for B10 cells. TNF-α elicited the proinflammatory feature of B10 and B10pro cells by downregulating IL-10, and upregulating interferon-γ and IL-17A. In patients with RA, B10 and B10pro cells were impaired with exacerbated proinflammatory phenotype, while anti-TNF therapy potently restored their frequencies and immunosuppressive functions, consistent with the increased B10 cells in TNF-α−/− mice. Mechanistically, TNF-α diminished B10 and B10pro cells by inhibiting their glycolysis and proliferation. TNF-α also regulated the phosphatidylinositol phosphate signalling of B10 and B10pro cells and dampened the expression of SHIP-1, a dominant phosphatidylinositol phosphatase regulator of these cells.ConclusionsTNF-α provoked the proinflammatory phenotype of B10 and B10pro cells by disturbing SHIP-1 in RA, contributing to the disease development. Reinstating the immunosuppressive property of B10 and B10pro cells might represent novel therapeutic approaches for RA.

The innate inflammatory response must be tightly regulated to ensure effective immune protection. NF-κB is a key mediator of the inflammatory response, and its dysregulation has been associated with immune-related malignancies. Here, we describe a miRNA-based regulatory network that enables precise NF-κB activity in mouse macrophages. Elevated miR-155 expression potentiates NF-κB activity in miR-146a-deficient mice, leading to both an overactive acute inflammatory response and chronic inflammation. Enforced miR-155 expression overrides miR-146a-mediated repression of NF-κB activation, thus emphasizing the dominant function of miR-155 in promoting inflammation. Moreover, miR-155-deficient macrophages exhibit a suboptimal inflammatory response when exposed to low levels of inflammatory stimuli. Importantly, we demonstrate a temporal asymmetry between miR-155 and miR-146a expression during macrophage activation, which creates a combined positive and negative feedback network controlling NF-κB activity. This miRNA-based regulatory network enables a robust yet time-limited inflammatory response essential for functional immunity. MicroRNAs (miR) are important regulators of gene transcription, with miR-155 and miR-146a both implicated in macrophage activation. Here the authors show that NF-κB signalling, miR-155 and miR-146a form a complex network of cross-regulations to control gene transcription in macrophages for modulating inflammatory responses.

Microglia and neuroinflammation play an important role in the development and progression of Alzheimer’s disease (AD). Inositol polyphosphate-5-phosphatase D ( INPP5D/SHIP1 ) is a myeloid-expressed gene genetically-associated with AD. Through unbiased analyses of RNA and protein profiles in INPP5D-disrupted iPSC-derived human microglia, we find that reduction in INPP5D activity is associated with molecular profiles consistent with disrupted autophagy and inflammasome activation. These findings are validated through targeted pharmacological experiments which demonstrate that reduced INPP5D activity induces the formation of the NLRP3 inflammasome, cleavage of CASP1, and secretion of IL-1β and IL-18. Further, in-depth analyses of human brain tissue across hundreds of individuals using a multi-analytic approach provides evidence that a reduction in function of INPP5D in microglia results in inflammasome activation in AD. These findings provide insights into the molecular mechanisms underlying microglia-mediated processes in AD and highlight the inflammasome as a potential therapeutic target for modulating INPP5D-mediated vulnerability to AD. INPP5D/SHIP1 is a microglial-expressed gene that has been associated with Alzheimer’s disease through genetic studies. This study reveals that reduction in INPP5D activity induces activation of the NLRP3-inflammasome in human microglia.

Endocytosis mediates the cellular uptake of micronutrients and the turnover of plasma membrane proteins. Clathrin-mediated endocytosis is the major uptake pathway in resting cells 1 , but several clathrin-independent endocytic routes exist in parallel 2 , 3 . One such pathway, fast endophilin-mediated endocytosis (FEME), is not constitutive but triggered upon activation of certain receptors, including the β 1 adrenergic receptor 4 . FEME activates promptly following stimulation as endophilin is pre-enriched by the phosphatidylinositol-3,4-bisphosphate-binding protein lamellipodin 4 , 5 . However, in the absence of stimulation, endophilin foci abort and disassemble after a few seconds. Looking for additional proteins involved in FEME, we found that 20 out of 65 BAR domain-containing proteins tested colocalized with endophilin spots. Among them, FBP17 and CIP4 prime the membrane of resting cells for FEME by recruiting the 5′-lipid phosphatase SHIP2 and lamellipodin to mediate the local production of phosphatidylinositol-3,4-bisphosphate and endophilin pre-enrichment. Membrane-bound GTP-loaded Cdc42 recruits FBP17 and CIP4, before being locally deactivated by RICH1 and SH3BP1 GTPase-activating proteins. This generates the transient assembly and disassembly of endophilin spots, which lasts 5–10 seconds. This mechanism periodically primes patches of the membrane for prompt responses upon FEME activation. Chan Wah Hak et al. show how plasma membrane patches are primed for fast endophilin-mediated endocytosis and disassembly, in the absence of receptor stimulation, through FBP17 and CIP4 binding to SHIP2 and lamellipodin.

The src homology 2 domain-containing inositol 5-phosphatases SHIP1 and SHIP2 are two proteins involved in intracellular signaling pathways and have been linked to the pathogenesis of several diseases. Both protein paralogs are well known for their involvement in the formation of various kinds of cancer. SHIP1, which is expressed predominantly in hematopoietic cells, has been implicated as a tumor suppressor in leukemogenesis especially in myeloid leukemia, whereas SHIP2, which is expressed ubiquitously, has been implicated as an oncogene in a wider variety of cancer types and is suggested to be involved in the process of metastasis of carcinoma cells. However, there are numerous other diseases, such as inflammatory diseases as well as allergic responses, Alzheimer’s disease, and stroke, in which SHIP1 can play a role. Moreover, SHIP2 overexpression was shown to correlate with opsismodysplasia and Alzheimer’s disease, as well as metabolic diseases. The SHIP1-inhibitor 3-α-aminocholestane (3AC), and SHIP1-activators, such as AQX-435 and AQX-1125, and SHIP2-inhibitors, such as K161 and AS1949490, have been developed and partly tested in clinical trials, which indicates the importance of the SHIP-paralogs as possible targets in the therapy of those diseases. The aim of this article is to provide an overview of the current knowledge about the involvement of SHIP proteins in the pathogenesis of cancer and other human diseases and to create awareness that SHIP1 and SHIP2 are more than just tumor suppressors and oncogenes.