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Microglia play a pivotal role in the pathology of Alzheimer's Disease (AD), with the Triggering Receptor Expressed on Myeloid cells 2 (TREM2) central to their neuroprotective functions. The R47H variant of TREM2 has emerged as a significant genetic risk factor for AD, leading to a loss-of-function phenotype in mouse AD models. This study elucidates the roles of TREM2 in human microglia-like HMC3 cells and the regulation of these functions by SH2-containing inositol-5'-phosphatase 1 (SHIP1). Using stable cell lines expressing wild-type TREM2, the R47H variant, and TREM2-deficient lines, we found that functional TREM2 is essential for the phagocytosis of Aβ, lysosomal capacity, and mitochondrial activity. Notably, the R47H variant displayed increased phagocytic activity towards apoptotic neurons. Introducing SHIP1, known to modulate TREM2 signaling in other cells, revealed its role as a negative regulator of these TREM2-mediated functions. Moreover, pharmacological inhibition of both SHIP1 and its isoform SHIP2 amplified Aβ phagocytosis and lysosomal capacity, independently of TREM2 or SHIP1 expression, suggesting a potential regulatory role for SHIP2 in these functions. The absence of TREM2, combined with the presence of both SHIP isoforms, suppressed mitochondrial activity. However, pan-SHIP1/2 inhibition enhanced mitochondrial function in these cells. In summary, our findings offer a deeper understanding of the relationship between TREM2 variants and SHIP1 in microglial functions, and emphasize the therapeutic potential of targeting the TREM2 and SHIP1 pathways in microglia for neurodegenerative diseases., Competing Interests: Declaration of Competing Interest WGK, CP and JDC have patents issued and pending regarding the use of SHIP paralog inhibitors in disease. The other authors declare no conflict of interest., (Published by Elsevier Ltd.)

Src homology 2 domain-containing inositol 5-phosphatase 1 (SHIP-1) regulates the intracellular levels of phosphotidylinositol-3, 4, 5-trisphosphate, a phosphoinositide 3-kinase (PI3K) product. Emerging evidence suggests that the PI3K pathway is involved in allergic inflammation in the lung. Germline or induced whole-body deletion of SHIP-1 in mice led to spontaneous type 2-dominated pulmonary inflammation, demonstrating that SHIP-1 is essential for lung homeostasis. However, the mechanisms by which SHIP-1 regulates lung inflammation and the responsible cell types are still unclear. Deletion of SHIP-1 selectively in B cells, T cells, dendritic cells (DC) or macrophages did not lead to spontaneous allergic inflammation in mice, suggesting that innate immune cells, particularly group 2 innate lymphoid cells (ILC2 cells) may play an important role in this process. We tested this idea using mice with deletion of SHIP-1 in the hematopoietic cell lineage and examined the changes in ILC2 cells. Conditional deletion of SHIP-1 in hematopoietic cells in Tek-Cre/SHIP-1 mice resulted in spontaneous pulmonary inflammation with features of type 2 immune responses and airway remodeling like those seen in mice with global deletion of SHIP-1. Furthermore, when compared to wild-type control mice, Tek-Cre/SHIP-1 mice displayed a significant increase in the number of IL-5/IL-13 producing ILC2 cells in the lung at baseline and after stimulation by allergen Papain. These findings provide some hints that PI3K signaling may play a role in ILC2 cell development at baseline and in response to allergen stimulation. SHIP-1 is required for maintaining lung homeostasis potentially by restraining ILC2 cells and type 2 inflammation.

Modulating the activity of the Src Homology 2 (SH2) - containing Inositol 5'-Phosphatase (SHIP) enzyme family with small molecule inhibitors provides a useful and unconventional method of influencing cell signaling in the PI3K pathway. The development of small molecules that selectively target one of the SHIP paralogs (SHIP1 or SHIP2) as well as inhibitors that simultaneously target both enzymes have provided promising data linking the phosphatase activity of the SHIP enzymes to disorders and disease states that are in dire need of new therapeutic targets. These include cancer, immunotherapy, diabetes, obesity, and Alzheimer's disease. In this mini-review, we will provide a brief overview of research in these areas that support targeting SHIP1, SHIP2 or both enzymes for therapeutic purposes., (© 2020 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Src Homology 2-containing Inositol Phosphatase-1 (SHIP-1) is a target of miR-155, a pro-inflammatory factor. Deletion of the SHIP-1 gene in mice caused spontaneous lung inflammation and fibrosis. However, the role and function of endothelial miR-155 and SHIP-1 in lung fibrosis remain unknown. Using whole-body miR-155 knockout mice and endothelial cell-specific conditional miR-155 (VEC-Cre-miR-155 or VEC-miR-155) or SHIP-1 (VEC-SHIP-1) knockout mice, we assessed endothelial-mesenchymal transition (EndoMT) and fibrotic responses in bleomycin (BLM) induced lung fibrosis models. Primary mouse lung endothelial cells (MLEC) and human umbilical vein endothelial cells (HUVEC) with SHIP-1 knockdown were analyzed in TGF-β1 or BLM, respectively, induced fibrotic responses. Fibrosis and EndoMT were significantly reduced in miR-155KO mice and changes in EndoMT markers in MLEC after TGF-β1 stimulation confirmed the in vivo findings. Furthermore, lung fibrosis and EndoMT responses were reduced in VEC-miR-155 mice but significantly enhanced in VEC-SHIP-1 mice after BLM challenge. SHIP-1 knockdown in HUVEC cells resulted in enhanced EndoMT induced by BLM. Meanwhile, these changes involved the PI3K/AKT, JAK/STAT3, and SMAD/STAT signaling pathways. These studies demonstrate that endothelial miR-155 plays an important role in fibrotic responses in the lung through EndoMT. Endothelial SHIP-1 is essential in controlling fibrotic responses and SHIP-1 is a target of miR-155. Endothelial cells are an integral part in lung fibrosis., (© 2019 Federation of American Societies for Experimental Biology.)

Balanced activity of kinases and phosphatases downstream of the BCR is essential for B cell differentiation and function and is disturbed in chronic lymphocytic leukemia (CLL). In this study, we employed IgH.TEμ mice, which spontaneously develop CLL, and stable EMC CLL cell lines derived from these mice to explore the role of phosphatases in CLL. Genome-wide expression profiling comparing IgH.TEμ CLL cells with wild-type splenic B cells identified 96 differentially expressed phosphatase genes, including SH2-containing inositol phosphatase ( Ship2 ). We found that B cell-specific deletion of Ship2 , but not of its close homolog Ship1 , significantly reduced CLL formation in IgH.TEμ mice. Treatment of EMC cell lines with Ship1/2 small molecule inhibitors resulted in the induction of caspase-dependent apoptosis. Using flow cytometry and Western blot analysis, we observed that blocking Ship1/2 abrogated EMC cell survival by exerting dual effects on the BCR signaling cascade. On one hand, specific Ship1 inhibition enhanced calcium signaling and thereby abrogated an anergic response to BCR stimulation in CLL cells. On the other hand, concomitant Ship1/Ship2 inhibition or specific Ship2 inhibition reduced constitutive activation of the mTORC1/ribosomal protein S6 pathway and downregulated constitutive expression of the antiapoptotic protein Mcl-1, in both EMC cell lines and primary IgH.TEμ CLL cells. Importantly, also in human CLL, we found overexpression of many phosphatases including SHIP2. Inhibition of SHIP1/SHIP2 reduced cellular survival and S6 phosphorylation and enhanced basal calcium levels in human CLL cells. Taken together, we provide evidence that SHIP2 contributes to CLL pathogenesis in mouse and human CLL., (Copyright © 2020 by The American Association of Immunologists, Inc.)

β-Glucan-induced trained immunity in myeloid cells leads to long-term protection against secondary infections. Although previous studies have characterized this phenomenon, strategies to boost trained immunity remain undefined. We found that β-glucan-trained macrophages from mice with a myeloid-specific deletion of the phosphatase SHIP-1 (LysMΔSHIP-1) showed enhanced proinflammatory cytokine production in response to lipopolysaccharide. Following β-glucan training, SHIP-1-deficient macrophages exhibited increased phosphorylation of Akt and mTOR targets, correlating with augmented glycolytic metabolism. Enhanced training in the absence of SHIP-1 relied on histone methylation and acetylation. Trained LysMΔSHIP-1 mice produced increased amounts of proinflammatory cytokines upon rechallenge in vivo and were better protected against Candida albicans infection compared with control littermates. Pharmacological inhibition of SHIP-1 enhanced trained immunity against Candida infection in mouse macrophages and human peripheral blood mononuclear cells. Our data establish proof of concept for improvement of trained immunity and a strategy to achieve it by targeting SHIP-1., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

In our previous study, we observed a severe reduction in the Src homology 2-containing-inositol-phosphatase-1 (SHIP1) protein in a subpopulation of subjects from a small adult Crohn's Disease (CD) cohort. This pilot study had been undertaken since we had previously demonstrated that engineered deficiency of SHIP1 in mice results in a spontaneous and severe CD-like ileitis. Here, we extend our analysis of SHIP1 expression in peripheral blood mononuclear cells in a second much larger adult Inflammatory Bowel Disease (IBD) cohort, comprised of both CD and Ulcerative Colitis patients, to assess contribution of SHIP1 to the pathogenesis of human IBD. SHIP1 protein and mRNA levels were evaluated from blood samples obtained from IBD subjects seen at UCSF/SFVA, and compared to healthy control samples. Western blot analyses revealed that ~15% of the IBD subjects are severely SHIP1-deficient, with less than 10% of normal SHIP1 protein present in PBMC. Further analyses by flow cytometry and sequencing were performed on secondary samples obtained from the same subjects. Pan-hematolymphoid SHIP1 deficiency was a stable phenotype and was not due to coding changes in the INPP5D gene. A very strong association between SHIP1 deficiency and the presence of a novel SHIP1:ATG16L1 fusion transcript was seen. Similar to SHIP1-deficient mice, SHIP1-deficient subjects had reduced numbers of circulating CD4 + T cell numbers. Finally, SHIP1-deficient subjects with CD had a history of severe disease requiring multiple surgeries. These studies reveal that the SHIP1 protein is crucial for normal T cell homeostasis in both humans and mice, and that it is also a potential therapeutic and/or diagnostic target in human IBD.

The success of immunotherapy in some cancer patients has revealed the profound capacity for cytotoxic lymphocytes to eradicate malignancies. Various immunotherapies work by blocking key checkpoint proteins that suppress immune cell activity. The phosphatase SHIP1 (SH2-containing inositol polyphosphate 5-phosphatase) limits signaling from receptors that activate natural killer (NK) cells and T cells. However, unexpectedly, genetic ablation studies have shown that the effector functions of SHIP1-deficient NK and T cells are compromised in vivo. Because chronic activation of immune cells renders them less responsive to activating signals (a host mechanism to avoid autoimmunity), we hypothesized that the failure of SHIP1 inhibition to induce antitumor immunity in those studies was caused by the permanence of genetic ablation. Accordingly, we found that reversible and pulsatile inhibition of SHIP1 with 3-α-aminocholestane (3AC; "SHIPi") increased the antitumor response of NK and CD8 + T cells in vitro and in vivo. Transient SHIP1 inhibition in mouse models of lymphoma and colon cancer improved the median and long-term tumor-free survival rates. Adoptive transfer assays showed evidence of immunological memory to the tumor in hematolymphoid cells from SHIPi-treated, long-term surviving mice. The findings suggest that a pulsatile regimen of SHIP1 inhibition might be an effective immunotherapy in some cancer patients., (Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Background: SH2 domain containing inositol-5-phosphatase (SHIP1) is an important modulator of innate and adaptive immunity. In mice, loss of SHIP1 provokes severe ileitis resembling Crohn's disease (CD), as a result of deregulated immune responses, altered cytokine production and intestinal fibrosis. Recently, SHIP1 activity was shown to be correlated to the presence of a CD-associated single nucleotide polymorphism in ATG16L1. Here, we studied SHIP1 activity and expression in an adult cohort of CD patients., Methods: SHIP1 activity, protein and mRNA expression in peripheral blood mononuclear cells from CD patients in clinical remission were determined by Malachite green assay, Western blotting and qRT-PCR respectively. Genomic DNA was genotyped for ATG16L1 rs2241880., Results: SHIP1 protein levels are profoundly diminished in a subset of patients; however, SHIP1 activity and expression are not correlated to ATG16L1 SNP status in this adult cohort., Conclusions: Aberrant SHIP1 activity can contribute to disease in a subset of adult CD patients, and warrants further investigation.

Colorectal cancer (CRC) is the second most common cause of cancer-related death, encouraging the search for novel therapeutic targets affecting tumor cell proliferation and migration. These cellular processes are under tight control of two opposing groups of enzymes; kinases and phosphatases. Aberrant activity of kinases is observed in many forms of cancer and as phosphatases counteract such "oncogenic" kinases, it is generally assumed that phosphatases function as tumor suppressors. However, emerging evidence suggests that the lipid phosphatase SH2-domain-containing 5 inositol phosphatase (SHIP2), encoded by the INPPL1 gene, may act as an oncogene. Just like the well-known tumor suppressor gene Phosphatase and Tensin Homolog (PTEN) it hydrolyses phosphatidylinositol (3,4,5) triphosphate (PI(3,4,5)P3). However, unlike PTEN, the reaction product is PI(3,4)P2, which is required for full activation of the downstream protein kinase B (PKB/Akt), suggesting that SHIP2, in contrast to PTEN, could have a tumor initiating role through PKB activation. In this work, we investigated the role of SHIP2 in colorectal cancer. We found that SHIP2 and INPPL1 expression is increased in colorectal cancer tissue in comparison to adjacent normal tissue, and this is correlated with decreased patient survival. Moreover, SHIP2 is more active in colorectal cancer tissue, suggesting that SHIP2 can induce oncogenesis in colonic epithelial cells. Furthermore, in vitro experiments performed on colorectal cancer cell lines shows an oncogenic role for SHIP2, by enhancing chemoresistance, cell migration, and cell invasion. Together, these data indicate that SHIP2 expression contributes to the malignant potential of colorectal cancer, providing a possible target in the fight against this devastating disease.