STING governs RCC growth through mitochondrial regulation of VDAC2
Ontology highlight
ABSTRACT: STING is an innate immune sensor for immune surveillance of viral or bacterial infection and maintenance of an immune-friendly microenvironment to unfavored tumorigenesis. Whether and how STING exerts any innate immunity independent function remains elusive. Here, we report that STING expression is increased in RCC patients and STING governs RCC growth through non-canonical innate immune signaling by maintaining mitochondrial ROS and calcium homeostasis. Mechanistically, we identify mitochondrial calcium transporter VDAC2 as a new STING binding partner and downstream effector, through suppression of which STING controls proper mitochondrial ROS/calcium levels. We also find palmitoylation of STING-C88/C91 residues is critical to mediate STING interaction with VDAC2 and inhibiting STING palmitoyl-transferases ZDHHCs by 2-BP significantly impedes RCC cell growth. Together, our studies reveal an innate immunity-independent function of STING in regulating RCC mitochondrial function and growth. We hope our study provides a rationale to apply palmitoylation inhibitors to treating RCC.
Project description:Voltage dependent anion channel 2 (VDAC2) is an outer mitochondrial membrane porin known to play a significant role in apoptosis and calcium signaling. Abnormalities in calcium homeostasis often leads to electrical and contractile dysfunction and can cause dilated cardiomyopathy and heart failure. However, the specific role of VDAC2 in intracellular calcium dynamics and cardiac function is not well understood. To elucidate the role of VDAC2 in calcium homeostasis, we generated a cardiac ventricular myocyte-specific developmental deletion of Vdac2 in mice. Our results indicate that loss of VDAC2 in the myocardium causes severe impairment in excitation-contraction coupling by altering both intracellular and mitochondrial calcium signaling. We also observed adverse cardiac remodeling which progressed to severe cardiomyopathy and death. Reintroduction of VDAC2 in 6-week-old knock-out mice partially rescued the cardiomyopathy phenotype. Activation of VDAC2 by efsevin increased cardiac contractile force in a mouse model of pressure-overload induced heart failure. In conclusion, our findings demonstrate that VDAC2 plays a crucial role in cardiac function by influencing cellular calcium signaling. Through this novel role in cellular calcium dynamics and excitation-contraction coupling VDAC2 emerges as a plausible therapeutic target for heart failure.
Project description:Intrinsic apoptosis is critical for normal physiology including the prevention of tumor formation. BAX and BAK, which are essential for mediating this process and for the cytotoxic action of many anti-cancer drugs, are thought to be regulated through similar mechanisms and act redundantly to drive apoptosis. Here we have established the various mitochondrial complexes that contain VDAC1, VDAC2, VDAC3 and BAX or BAK.
Project description:ATAC-seq analysis of the functional effect of targeting Vdac2 in tumor cells under the condition of chronic IFNg stimulation that induces IFNg resistance.
Project description:A breach in tolerance to self-antigens induces expansion of autoreactive T cells, ultimately leading to autoimmune inflammation. While autoreactive T cells are principal drivers of autoimmunity, tissue pathology is alternatively driven by innate cytokines, indicating that autoreactive T cells can induce innate inflammation. This study has led to the discovery that effector memory T (Tem) cells trigger double stranded breaks via mitochondrial ROS production in interacting DCs. Consequently, initiation of the DNA damage response leads to activation of a cGAS-independent, STING-TRAF6-NFkB signaling axis. STING deficient DCs display significant defects in transcriptional induction and functional production of IL-1b and IL-6 following their interaction with Tem cells, both in vitro and in vivo. The discovery of Tem induced innate inflammation through DNA damage and a non-canonical STING-mediated NFkB activation presents this pathway as a potential target to alleviate T cell driven autoimmune inflammation.
Project description:A breach in tolerance to self-antigens induces expansion of autoreactive T cells, ultimately leading to autoimmune inflammation. While autoreactive T cells are principal drivers of autoimmunity, tissue pathology is alternatively driven by innate cytokines, indicating that autoreactive T cells can induce innate inflammation. This study has led to the discovery that effector memory T (Tem) cells trigger double stranded breaks via mitochondrial ROS production in interacting DCs. Consequently, initiation of the DNA damage response leads to activation of a cGAS-independent, STING-TRAF6-NFkB signaling axis. STING deficient DCs display significant defects in transcriptional induction and functional production of IL-1b and IL-6 following their interaction with Tem cells, both in vitro and in vivo. The discovery of Tem induced innate inflammation through DNA damage and a non-canonical STING-mediated NFkB activation presents this pathway as a potential target to alleviate T cell driven autoimmune inflammation.
Project description:Chronic stimulation of innate immune pathways by microbial agents or damaged tissue is known to promote inflammation-driven tumorigenesis by unclarified mechanisms1-3. Here we demonstrate that mutagenic 7,12-dimethylbenz(a)anthracene (DMBA), etoposide or cisplatin induces nuclear DNA leakage into the cytosol to intrinsically activate STING (Stimulator of Interferon Genes) dependent cytokine production. Inflammatory cytokine levels were subsequently augmented in a STING-dependent extrinsic manner by infiltrating phagocytes purging dying cells. Consequently, STING-/- mice, or wild type mice adoptively transferred with STING-/- bone marrow, were almost completely resistant to DMBA-induced skin carcinogenesis compared to their wild type counterparts. Our data emphasizes, for the first time, a role for STING in the induction of cancer, sheds significant insight into the causes of inflammation-driven carcinogenesis, and may provide therapeutic strategies to help prevent malignant disease Total RNA obtained from DMBA or acetone treated wild type (WT) or STING deficient (SKO) mouse skin or skin tumor was examined for gene expression.