413 research outputs found

    The IKKâ related kinase TBK1 activates mTORC1 directly in response to growth factors and innate immune agonists

    Full text link
    The innate immune kinase TBK1 initiates inflammatory responses to combat infectious pathogens by driving production of type I interferons. TBK1 also controls metabolic processes and promotes oncogeneâ induced cell proliferation and survival. Here, we demonstrate that TBK1 activates mTOR complex 1 (mTORC1) directly. In cultured cells, TBK1 associates with and activates mTORC1 through siteâ specific mTOR phosphorylation (on S2159) in response to certain growth factor receptors (i.e., EGFâ receptor but not insulin receptor) and pathogen recognition receptors (PRRs) (i.e., TLR3; TLR4), revealing a stimulusâ selective role for TBK1 in mTORC1 regulation. By studying cultured macrophages and those isolated from genome edited mTOR S2159A knockâ in mice, we show that mTOR S2159 phosphorylation promotes mTORC1 signaling, IRF3 nuclear translocation, and IFNâ β production. These data demonstrate a direct mechanistic link between TBK1 and mTORC1 function as well as physiologic significance of the TBK1â mTORC1 axis in control of innate immune function. These data unveil TBK1 as a direct mTORC1 activator and suggest unanticipated roles for mTORC1 downstream of TBK1 in control of innate immunity, tumorigenesis, and disorders linked to chronic inflammation.SynopsisTBK1, an IKKâ related kinase that drives interferon production as well cancer cell proliferation and survival, phosphorylates mTOR to activate mTORC1 in response to EGF and innate immune agonists, suggesting unanticipated roles for mTORC1 downstream of TBK1 in control of innate immunity and tumorigenesis.TBK1 interacts with mTORC1 and phosphorylates mTOR on S2159 to increase its catalytic activity.Cells lacking TBK1 or expressing a mTOR S2159A allele exhibit reduced mTORC1 signaling in response to EGFâ receptor and TLR3/4 activation.Primary macrophages derived from genome edited mTOR S2159A mice exhibit reduced mTORC1 signaling in response to TLR3/4 activation.Primary macrophages treated with rapamycin as well as those derived from mTORS2159A mice produce reduced levels of IFNâ β due to impaired nuclear translocation of the transcription factor IRF3.Innate immune kinase TBK1â dependent activation of mTORC1 occurs in response to pathogen recognition and EGF receptor activation and drives interferon production, thus highlighting the role of mTOR for innate immunity.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141029/1/embj201696164.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141029/2/embj201696164.reviewer_comments.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141029/3/embj201696164_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141029/4/embj201696164-sup-0001-EVFigs.pd

    mTORC1 Inhibition via Rapamycin Promotes Triacylglycerol Lipolysis and Release of Free Fatty Acids in 3T3â L1 Adipocytes

    Full text link
    Signaling by mTOR complex 1 (mTORC1) promotes anabolic cellular processes in response to growth factors, nutrients, and hormonal cues. Numerous clinical trials employing the mTORC1 inhibitor rapamycin (aka sirolimus) to immunoâ suppress patients following organ transplantation have documented the development of hypertriglyceridemia and elevated serum free fatty acids (FFA). We therefore investigated the cellular role of mTORC1 in control of triacylglycerol (TAG) metabolism using cultured murine 3T3â L1 adipocytes. We found that treatment of adipocytes with rapamycin reduced insulinâ stimulated TAG storage ~50%. To determine whether rapamycin reduces TAG storage by upregulating lipolytic rate, we treated adipocytes in the absence and presence of rapamycin and isoproterenol, a β2â adrenergic agonist that activates the cAMP/protein kinase A (PKA) pathway to promote lipolysis. We found that rapamycin augmented isoproterenolâ induced lipolysis without altering cAMP levels. Rapamycin enhanced the isoproterenolâ stimulated phosphorylation of hormone sensitive lipase (HSL) on Serâ 563 (a PKA site), but had no effect on the phosphorylation of HSL S565 (an AMPK site). Additionally, rapamycin did not affect the isoproterenolâ mediated phosphorylation of perilipin, a protein that coats the lipid droplet to initiate lipolysis upon phosphorylation by PKA. These data demonstrate that inhibition of mTORC1 signaling synergizes with the βâ adrenergicâ cAMP/PKA pathway to augment phosphorylation of HSL to promote hormoneâ induced lipolysis. Moreover, they reveal a novel metabolic function for mTORC1; mTORC1 signaling suppresses lipolysis, thus augmenting TAG storage.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141428/1/lipd1089.pd

    Potentiation of the anti-tumour effects of Photofrin®-based photodynamic therapy by localized treatment with G-CSF

    Get PDF
    Photofrin®-based photodynamic therapy (PDT) has recently been approved for palliative and curative purposes in cancer patients. It has been demonstrated that neutrophils are indispensable for its anti-tumour effectiveness. We decided to evaluate the extent of the anti-tumour effectiveness of PDT combined with administration of granulocyte colony-stimulating factor (G-CSF) as well as the influence of Photofrin®and G-CSF on the myelopoiesis and functional activity of neutrophils in mice. An intensive treatment with G-CSF significantly potentiated anti-tumour effectiveness of Photofrin®-based PDT resulting in a reduction of tumour growth and prolongation of the survival time of mice bearing two different tumours: colon-26 and Lewis lung carcinoma. Moreover, 33% of C-26-bearing mice were completely cured of their tumours after combined therapy and developed a specific and long-lasting immunity. The tumours treated with both agents contained more infiltrating neutrophils and apoptotic cells then tumours treated with either G-CSF or PDT only. Importantly, simultaneous administration of Photofrin®and G-CSF stimulated bone marrow and spleen myelopoiesis that resulted in an increased number of neutrophils demonstrating functional characteristics of activation. Potentiated anti-tumour effects of Photofrin®-based PDT combined with G-CSF observed in two murine tumour models suggest that clinical trials using this tumour therapy protocol would be worth pursuing. © 2000 Cancer Research Campaig

    Activation of mTOR coincides with autophagy during ligation-induced atrophy in the rat submandibular gland

    Get PDF
    Salivary gland atrophy is a common consequence of pathology, including Sjögren's syndrome, irradiation therapy and obstructive sialadenitis. During severe atrophy of the rat submandibular gland caused by excretory duct ligation, the majority of acinar cells disappear through apoptosis, whereas ductal cells proliferate and dedifferentiate; yet, the gland can survive in the atrophic state almost indefinitely, with an ability to fully recover if deligated. The control mechanisms governing these observations are not well understood. We report that ∼10% of acinar cells survive in ligation-induced atrophy. Microarray and quantitative real-time PCR analysis of ligated glands indicated sustained transcription of acinar cell-specific genes, whereas ductal-specific genes were reduced to background levels. After 3 days of ligation, activation of the mammalian target of rapamycin (mTOR) pathway and autophagy occurred as shown by phosphorylation of 4E-BP1 and expression of autophagy-related proteins. These results suggest that activation of mTOR and the autophagosomal pathway are important mechanisms that may help to preserve acinar cells during atrophy of salivary glands after injury

    LKB1/KRAS mutant lung cancers constitute a genetic subset of NSCLC with increased sensitivity to MAPK and mTOR signalling inhibition

    Get PDF
    LKB1/STK11 is a multitasking tumour suppressor kinase. Germline inactivating mutations of the gene are responsible for the Peutz-Jeghers hereditary cancer syndrome. It is also somatically inactivated in approximately 30% of non-small-cell lung cancer (NSCLC). Here, we report that LKB1/KRAS mutant NSCLC cell lines are sensitive to the MEK inhibitor CI-1040 shown by a dose-dependent reduction in proliferation rate, whereas LKB1 and KRAS mutations alone do not confer similar sensitivity. We show that this subset of NSCLC is also sensitised to the mTOR inhibitor rapamycin. Importantly, the data suggest that LKB1/KRAS mutant NSCLCs are a genetically and functionally distinct subset and further suggest that this subset of lung cancers might afford an opportunity for exploitation of anti-MAPK/mTOR-targeted therapies
    corecore