Project description:STING1 is an essential component of the innate immune defense against a wide variety of pathogens. Whereas induction of Type I interferon (IFN) responses is one of the best-defined functions of STING1, our transcriptomic analysis revealed IFN-independent activities of STING1 in macrophages, including transcriptional upregulation of numerous lysosomal and autophagic genes. This upregulation was mediated by the STING1-induced activation of the transcription factors TFEB and TFE3, and led to increased autophagy, lysosomal biogenesis, and lysosomal acidification. TFEB and TFE3 also modulated IFN-dependent STING1 signaling by controlling IRF3 activation. IFN production and cell death were increased in TFEB and TFE3 depleted iBMDMs. Conversely, TFEB over-expression led to reduced IRF3 activation and an almost complete inhibition of interferon synthesis and secretion, resulting in decrease caspase-3 activation and increased cell survival. Our study reveals a key role of TFEB and TFE3 as regulators of STING1-mediated innate antiviral immunity.
Project description:STING1 is an essential component of the innate immune defense against a wide variety of pathogens. Whereas induction of Type I interferon (IFN) responses is one of the best-defined functions of STING1, our transcriptomic analysis revealed IFN-independent activities of STING1 in macrophages, including transcriptional upregulation of numerous lysosomal and autophagic genes. This upregulation was mediated by the STING1-induced activation of the transcription factors TFEB and TFE3, and led to increased autophagy, lysosomal biogenesis, and lysosomal acidification. TFEB and TFE3 also modulated IFN-dependent STING1 signaling by controlling IRF3 activation. IFN production and cell death were increased in TFEB and TFE3 depleted iBMDMs. Conversely, TFEB over-expression led to reduced IRF3 activation and an almost complete inhibition of interferon synthesis and secretion, resulting in decrease caspase-3 activation and increased cell survival. Our study reveals a key role of TFEB and TFE3 as regulators of STING1-mediated innate antiviral immunity.
Project description:STING1 is an essential component of the innate immune defense against a wide variety of pathogens. Whereas induction of Type I interferon (IFN) responses is one of the best-defined functions of STING1, our transcriptomic analysis revealed IFN-independent activities of STING1 in macrophages, including transcriptional upregulation of numerous lysosomal and autophagic genes. This upregulation was mediated by the STING1-induced activation of the transcription factors TFEB and TFE3, and led to increased autophagy, lysosomal biogenesis, and lysosomal acidification. TFEB and TFE3 also modulated IFN-dependent STING1 signaling by controlling IRF3 activation. IFN production and cell death were increased in TFEB and TFE3 depleted iBMDMs. Conversely, TFEB over-expression led to reduced IRF3 activation and an almost complete inhibition of interferon synthesis and secretion, resulting in decrease caspase-3 activation and increased cell survival. Our study reveals a key role of TFEB and TFE3 as regulators of STING1-mediated innate antiviral immunity.
Project description:Birt-Hogg-Dubè (BHD) syndrome is an inherited condition caused by loss-of-function mutations in the gene encoding the tumor-suppressor protein folliculin (FLCN) and frequently associated with kidney cysts and cancer. FLCN acts as a negative regulator of TFEB and TFE3 transcription factors, master controllers of lysosomal biogenesis and autophagy, by enabling their phosphorylation by the mechanistic Target Of Rapamycin Complex 1 (mTORC1). We previously showed that deletion of TFEB rescued the renal cystic phenotype of kidney-specific Flcn KO mice. Using Flcn/TFEB/TFE3 double and triple KO mice we now show that both TFEB and TFE3 contribute, in a differential and cooperative manner, to kidney cystogenesis. Importantly, silencing of either TFEB or TFE3 rescued tumorigenesis in patient-derived xenografts (PDXs) generated from a kidney tumor of a BHD patient. Furthermore, transcriptome analyses performed in transgenic mice, PDXs and patient tumor samples revealed TFEB/TFE3 downstream targets that may contribute to their tumorigenic activity. Our findings demonstrate in disease-relevant models that TFEB and TFE3 are key drivers of kidney tumorigenesis and suggest novel therapeutic strategies based on the inhibition of these transcription factors.
Project description:Unlike MITF-M, the melanocyte-specific isoform of MITF, TFEB, TFE3 and non-melanocyte MITF isoforms are regulated primarily by mTORC1-mediated phosphorylation at the lysosome that promotes their cytoplasmic retention. As low levels of glucose or amino acids trigger down-regulation of MITF, it is likely that on nutrient limitation some MITF functions are assumed by TFE3 and TFEB, enabling MITFLow melanoma cells to survive and proliferate. The role TFEB and TFE3 in melanoma biology and their impact on MITF-driven proliferation is poorly understood.
Project description:To analyze gene expression differences between cells silenced for TFEB and TFE3 vs. Controls, under growing conditions (GC) vs. Fasting conditions (Fast)
Project description:Lysosomal degradation of the endoplasmic reticulum (ER) via autophagy (ER-phagy) is emerging as a critical regulator of cell homeostasis and function1. The recent identification of ER-phagy receptors has shed light on the molecular mechanism underlining this process; however, the signaling pathways regulating ER-phagy in response to cellular needs are still largely unknown. We found that the nutrient responsive transcription factors TFEB and TFE3 - master regulators of lysosomal biogenesis and autophagy2- control ER-phagy by inducing the expression of the ER-phagy receptor FAM134B. The TFEB/TFE3-FAM134B axis promotes ER-phagy activation upon prolonged starvation. In addition, we discovered that this pathway is activated in chondrocytes by FGF signaling, a critical regulator of cell differentiation 3. FGF signaling induces a JNK-dependent proteasomal degradation of the insulin receptor substrate 1, which inhibits the insulin-PI3K-PKB/Akt-mTORC1 pathway and promotes TFEB/TFE3 nuclear translocation and FAM134B induction. Consistent with a role of the TFEB/TFE3-FAM134B axis in chondrocytes, FAM134B knock-down impairs cartilage growth and mineralization in medaka fish. This study identifies a new signaling pathway that allows ER-phagy to respond to both metabolic and developmental cues.