@article{gonzalez-calderon_lopez-perez_sai_ninomiya-tsuji_2024, title={TAK1 inhibition translocates pore-forming proteins, MLKL and gasdermins into mitochondria to generate reactive oxygen species}, volume={300}, ISSN={["1083-351X"]}, DOI={10.1016/j.jbc.2024.106731}, abstractNote={Mitogen-activated protein kinase kinase kinase 7 (MAP3K7), known as TAK1, is a central mediator of intracellular host defense signaling promoting inflammatory gene expression. Hence, TAK1 is a prime target of intracellular bacterial effectors in blocking inflammatory gene expression. However, when TAK1 is inhibited, host cells alternatively induce mitochondrial reactive oxygen species (ROS) to kill intracellular bacteria, which ultimately induces host cell death to prevent bacteria spreading. In the current study, we delineate the mechanism of how host cells elevate ROS and induce cell death in response to TAK1 inhibition in bone marrow derived macrophage (BMDMs). TAK1 inhibition activates multiple cell death pathways, namely caspase 8-dependent apoptosis and pyroptosis, and receptor interacting protein kinase 3 (RIPK3)-dependent necroptosis. While these pathways lead to host cell death, we found that mixed lineage kinase-like (MLKL) downstream RIPK3 and gasdermins (GSDMD and GSDME) downstream caspase 8 were translocated to mitochondria upon TAK1 inhibition. Deletion of both MLKL and gasdermins partially blocked TAK1 inhibition-induced mitochondrial ROS and exacerbated intracellular bacteria growth colonization. These results suggest that these cell-killing pore forming proteins play an alternative host defense role to prevent intracellular pathogen colonization by modulating mitochondria. Additionally, we found that ablation of both caspase 8 (apoptosis and pyroptosis) and RIPK3 (necroptosis) did not abolish TAK1 inhibition-induced cell death in BMDMs. Furthermore, we found that mice having TAK1, caspase 8 and RIPK3 triple deletion died within 8 days. These results suggest that an unidentified caspase 8 and RIPK3-independent cell killing pathway(s) is activated by TAK1 inhibition, which is another host defense mechanism. Our results demonstrate that apoptosis, pyroptosis, necroptosis together with unidentified pathways cooperatively act as the host defense in response to bacterial TAK1 inhibition. NIH R35GM139601.}, number={3}, journal={JOURNAL OF BIOLOGICAL CHEMISTRY}, author={Gonzalez-Calderon, Roland and Lopez-Perez, Wilfred and Sai, Kazuhito and Ninomiya-Tsuji, Jun}, year={2024}, month={Mar}, pages={S555–S555} } @article{nakanishi-hester_sai_ninomiya-tsuji_2024, title={The Mechanism and Roles of TAK1 hyperactivation in the Alzheimer's Disease Mouse Model}, volume={300}, ISSN={["1083-351X"]}, DOI={10.1016/j.jbc.2024.106732}, abstractNote={Neuroinflammation in the hippocampus is causally associated with Alzheimer's Disease (AD). However, the precise mechanisms of how inflammatory signaling in each cell type, neuron, oligodendrocyte, astrocyte, microglia, etc. impacts neuronal function remain elusive. Oligodendrocytes (OLGs), known for myelin formation and neuron support, emerge as potential contributors to chronic neuroinflammation. Unlike neurons, OLGs can regenerate throughout the lifespan, making them viable targets for understanding and potentially mitigating AD. We found that mitogen-activated protein kinase kinase kinase 7 (MAP3K7), also known as TAK1, a central player in intracellular inflammation signaling, is hyperactivated in the hippocampus of aged and AD model mice. We previously demonstrated that neuron lineage specific Tak1 gene deletion ameliorated neuron loss and cognitive impairment. These results suggest that TAK1-driven inflammatory signaling promotes AD. In our current study, my objectives are to elucidate the mechanism of TAK1 hyperactivation and its role, particularly, in OLGs. We found that compound stimulation of an inflammatory cytokine, TNF and a neurotransmitter glutamate-calcium influx activates TAK1. In addition, calcium calmodulin kinase II (CaMKII) is found to be involved in TAK1 activation by binding to and modulates TAK1 binding protein 2, TAB2. TAB2 serves a dual role in the regulation of TAK1 as it can recruit activators and deactivators of TAK1 and deleting Tab2 gene hyperactivates TAK1. These results collectively suggest that calcium-CaMKII-TAB2 blockade together with TNF hyperactivates TAK1. We are currently analyzing mice with OLG-specific Tab2 deletion (TAK1 hyper-activation). We found that Tab2 deletion blocks OLG differentiation, suggesting that TAK1 hyperactivation impairs OLG-derived support for neurons. Our results uncovered the importance of TAK1 in AD pathogenesis, offering potential avenues for therapeutic intervention. The study is funded by National Institute of Health, R35GM139601, 2019-AARG-NTF-641347.}, number={3}, journal={JOURNAL OF BIOLOGICAL CHEMISTRY}, author={Nakanishi-Hester, Aoi and Sai, Kazuhito and Ninomiya-Tsuji, Jun}, year={2024}, month={Mar}, pages={S556–S556} } @article{sai_nakanishi_scofield_tokarz_linder_cohen_ninomiya-tsuji_2023, title={Aberrantly activated TAK1 links neuroinflammation and neuronal loss in Alzheimer?s disease mouse models}, volume={136}, ISSN={["1477-9137"]}, url={http://dx.doi.org/10.1242/jcs.260102}, DOI={10.1242/jcs.260102}, abstractNote={ABSTRACT Neuroinflammation is causally associated with Alzheimer's disease (AD) pathology. Reactive glia cells secrete various neurotoxic factors that impair neuronal homeostasis eventually leading to neuronal loss. Although the glial activation mechanism in AD has been relatively well studied, how it perturbs intraneuronal signaling, which ultimately leads to neuronal cell death, remains poorly understood. Here, we report that compound stimulation with the neurotoxic factors TNF and glutamate aberrantly activates neuronal TAK1 (also known as MAP3K7), which promotes the pathogenesis of AD in mouse models. Glutamate-induced Ca2+ influx shifts TNF signaling to hyper-activate TAK1 enzymatic activity through Ca2+/calmodulin-dependent protein kinase II, which leads to necroptotic cellular damage. Genetic ablation and pharmacological inhibition of TAK1 ameliorated AD-associated neuronal loss and cognitive impairment in the AD model mice. Our findings provide a molecular mechanism linking cytokines, Ca2+ signaling and neuronal necroptosis in AD.}, number={6}, journal={JOURNAL OF CELL SCIENCE}, publisher={The Company of Biologists}, author={Sai, Kazuhito and Nakanishi, Aoi and Scofield, Kimberly M. and Tokarz, Debra A. and Linder, Keith E. and Cohen, Todd J. and Ninomiya-Tsuji, Jun}, year={2023}, month={Mar} } @article{lopez-perez_sai_sakamachi_parsons_kathariou_ninomiya-tsuji_2021, title={TAK1 inhibition elicits mitochondrial ROS to block intracellular bacterial colonization}, volume={118}, ISSN={["0027-8424"]}, url={https://doi.org/10.1073/pnas.2023647118}, DOI={10.1073/pnas.2023647118}, abstractNote={Significance We have found that bacterial inhibition of host TAK1 inflammatory signaling elicits an alternative host defense mechanism involving production of mitochondrial reactive oxygen species through caspase 8 and RIPK3. This finding allows a reinterpretation of mouse phenotypes harboring tissue-specific gene deletion of Tak1 , many of which die from tissue damage previously ascribed to impaired TAK1-dependent tissue homeostasis. We suggest that these phenotypes arise from misrecognition of compromised TAK1 as pathogen invasion. }, number={25}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, publisher={Proceedings of the National Academy of Sciences}, author={Lopez-Perez, Wilfred and Sai, Kazuhito and Sakamachi, Yosuke and Parsons, Cameron and Kathariou, Sophia and Ninomiya-Tsuji, Jun}, year={2021}, month={Jun} } @article{sai_parsons_house_kathariou_ninomiya-tsuji_2019, title={Necroptosis mediators RIPK3 and MLKL suppress intracellular Listeria replication independently of host cell killing}, volume={218}, ISSN={["1540-8140"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85067213651&partnerID=MN8TOARS}, DOI={10.1083/jcb.201810014}, abstractNote={RIPK3, a key mediator of necroptosis, has been implicated in the host defense against viral infection primary in immune cells. However, gene expression analysis revealed that RIPK3 is abundantly expressed not only in immune organs but also in the gastrointestinal tract, particularly in the small intestine. We found that orally inoculated Listeria monocytogenes, a bacterial foodborne pathogen, efficiently spread and caused systemic infection in Ripk3-deficient mice while almost no dissemination was observed in wild-type mice. Listeria infection activated the RIPK3-MLKL pathway in cultured cells, which resulted in suppression of intracellular replication of Listeria. Surprisingly, Listeria infection–induced phosphorylation of MLKL did not result in host cell killing. We found that MLKL directly binds to Listeria and inhibits their replication in the cytosol. Our findings have revealed a novel functional role of the RIPK3-MLKL pathway in nonimmune cell-derived host defense against Listeria invasion, which is mediated through cell death–independent mechanisms.}, number={6}, journal={JOURNAL OF CELL BIOLOGY}, publisher={Rockefeller University Press}, author={Sai, Kazuhito and Parsons, Cameron and House, John S. and Kathariou, Sophia and Ninomiya-Tsuji, Jun}, year={2019}, month={Jun}, pages={1994–2005} } @article{morioka_sai_omori_ikeda_matsumoto_ninomiya-tsuji_2016, title={TAK1 regulates hepatic lipid homeostasis through SREBP}, volume={35}, ISSN={["1476-5594"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84961218902&partnerID=MN8TOARS}, DOI={10.1038/onc.2015.453}, abstractNote={Sterol-regulatory element-binding proteins (SREBPs) are key transcription factors regulating cholesterol and fatty acid biosynthesis. SREBP activity is tightly regulated to maintain lipid homeostasis, and is modulated upon extracellular stimuli such as growth factors. While the homeostatic SREBP regulation is well studied, stimuli-dependent regulatory mechanisms are still elusive. Here we demonstrate that SREBPs are regulated by a previously uncharacterized mechanism through transforming growth factor-β activated kinase 1 (TAK1), a signaling molecule of inflammation. We found that TAK1 binds to and inhibits mature forms of SREBPs. In an in vivo setting, hepatocyte-specific Tak1 deletion upregulates liver lipid deposition and lipogenic enzymes in the mouse model. Furthermore, hepatic Tak1 deficiency causes steatosis pathologies including elevated blood triglyceride and cholesterol levels, which are established risk factors for the development of hepatocellular carcinoma (HCC) and are indeed correlated with Tak1-deficiency-induced HCC development. Pharmacological inhibition of SREBPs alleviated the steatosis and reduced the expression level of the HCC marker gene in the Tak1-deficient liver. Thus, TAK1 regulation of SREBP critically contributes to the maintenance of liver homeostasis to prevent steatosis, which is a potentially important mechanism to prevent HCC development.}, number={29}, journal={ONCOGENE}, author={Morioka, S. and Sai, K. and Omori, E. and Ikeda, Y. and Matsumoto, K. and Ninomiya-Tsuji, J.}, year={2016}, month={Jul}, pages={3829–3838} }