Project description:Mitochondria control bioenergetics and cell fate decisions, but whether they also participate in extra-organelle signaling is not understood. Here, we show that interference with cyclophilin D (CypD), a mitochondrial matrix protein and apoptosis regulator, causes accelerated cell proliferation and enhanced cell migration and invasion. These responses are associated with global transcriptional changes in CypD-/- cells, predominantly affecting chemokines and their receptors, and resulting in increased activating phosphorylation of Signal Transduction and Activator of Transcription 3 (STAT3). In turn, STAT3 signaling promotes increased proliferation of CypD-/- cells via accelerated S-phase entry and supports Cxcl12-directed paracrine cell motility. Therefore, mitochondria-to-nuclei transcriptional signaling globally affects cell division and motility. As immunosuppressive therapies often target CypD, this pathway may predispose the tissue microenvironment of these patients to oncogenic transformation. Three wild type (WT) and three CypD-/- knock-out mouse embryonic fibroblasts (MEFs) have been compared.
Project description:Mitochondria control bioenergetics and cell fate decisions, but whether they also participate in extra-organelle signaling is not understood. Here, we show that interference with cyclophilin D (CypD), a mitochondrial matrix protein and apoptosis regulator, causes accelerated cell proliferation and enhanced cell migration and invasion. These responses are associated with global transcriptional changes in CypD-/- cells, predominantly affecting chemokines and their receptors, and resulting in increased activating phosphorylation of Signal Transduction and Activator of Transcription 3 (STAT3). In turn, STAT3 signaling promotes increased proliferation of CypD-/- cells via accelerated S-phase entry and supports Cxcl12-directed paracrine cell motility. Therefore, mitochondria-to-nuclei transcriptional signaling globally affects cell division and motility. As immunosuppressive therapies often target CypD, this pathway may predispose the tissue microenvironment of these patients to oncogenic transformation.
Project description:Sphingolipids, ceramides and cholesterol are integral components of cellular membranes, and they also play important roles in signal transduction by regulating the dynamics of membrane receptors through their effects on membrane fluidity. Here, we combined biochemical and functional assays with single-molecule dynamic approaches to demonstrate that the local lipid environment regulates CXCR4 organization and function and modulates chemokine-triggered directed cell migration. Prolonged treatment of T cells with neutral sphingomyelinase promoted the complete and sustained breakdown of sphingomyelins and the accumulation of the corresponding ceramides, which altered both membrane fluidity and CXCR4 nanoclustering and dynamics. Under these conditions CXCR4 retained some CXCL12-mediated signaling activity but failed to promote efficient directed cell migration. Our data underscore a critical role for the local lipid composition at the cell membrane in regulating the lateral mobility of chemokine receptors, and their ability to dynamically increase receptor density at the leading edge to promote efficient cell migration