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
Project description:Chemokine signaling is important for the seeding of different sites by hematopoietic stem cells during development. Serum Response Factor (SRF) controls multiple genes governing adhesion and migration, mainly by recruiting members of the Myocardin-Related Transcription Factor (MRTF) family of G-actin regulated cofactors. We used vav-iCre to inactivate MRTF-SRF signaling early during hematopoietic development. In both Srf- and Mrtf-deleted animals, hematopoiesis in fetal liver and spleen is intact, but does not become established in fetal bone marrow. Srf-null HSC/Ps (hematopoietic stem/progenitor cells) fail to effectively engraft in transplantation experiments, exhibiting normal proximal signaling responses to SDF-1, but reduced adhesiveness, F-actin assembly, and reduced motility. Srf-null HSC/Ps fail to polarise in response to SDF-1, and cannot migrate through restrictive membrane pores to SDF-1 or Scf in vitro. Mrtf-null HSC/Ps were also defective in chemotactic responses to SDF-1. MRTF-SRF signaling is thus critical for the response to chemokine signaling during hematopoietic development. Strand specific RNA sequencing (RNA-seq) in sorted WT and SRF deleted LSK cells with or without a 30 minute SDF stimulation and validation by qRT-PCR
Project description:Chemokine signaling is important for the seeding of different sites by hematopoietic stem cells during development. Serum Response Factor (SRF) controls multiple genes governing adhesion and migration, mainly by recruiting members of the Myocardin-Related Transcription Factor (MRTF) family of G-actin regulated cofactors. We used vav-iCre to inactivate MRTF-SRF signaling early during hematopoietic development. In both Srf- and Mrtf-deleted animals, hematopoiesis in fetal liver and spleen is intact, but does not become established in fetal bone marrow. Srf-null HSC/Ps (hematopoietic stem/progenitor cells) fail to effectively engraft in transplantation experiments, exhibiting normal proximal signaling responses to SDF-1, but reduced adhesiveness, F-actin assembly, and reduced motility. Srf-null HSC/Ps fail to polarise in response to SDF-1, and cannot migrate through restrictive membrane pores to SDF-1 or Scf in vitro. Mrtf-null HSC/Ps were also defective in chemotactic responses to SDF-1. MRTF-SRF signaling is thus critical for the response to chemokine signaling during hematopoietic development.
Project description:Endochondral ossification is the process by which the appendicular skeleton, facial bones, vertebrae and medial clavicles are formed and relies on the tight control of chondrocyte maturation. Fibroblast growth factor receptor (FGFR)3 plays a role in bone development and maintenance and belongs to a family of proteins which differ in their ligand affinities and tissue distribution. Activating mutations of the FGFR3 gene lead to craniosynostosis and multiple types of skeletal dysplasia with varying degrees of severity: thanatophoric dysplasia (TD), achondroplasia and hypochondroplasia. Despite progress in the characterization of FGFR3-mediated regulation of cartilage development, many aspects remain unclear. The aim and the novelty of our study was to examine whole gene expression differences occurring in primary human chondrocytes isolated from normal cartilage or pathological cartilage from TD-affected fetuses, using Affymetrix technology. The phenotype of the primary cells was confirmed by the high expression of chondrocytic markers. Altered expression of genes associated with many cellular processes was observed, including cell growth and proliferation, cell cycle, cell adhesion, cell motility, metabolic pathways, signal transduction, cell cycle process and cell signaling. Most of the cell cycle process genes were down-regulated and consisted of genes involved in cell cycle progression, DNA biosynthesis, spindle dynamics and cytokinesis. About eight percent of all modulated genes were found to impact extracellular matrix (ECM) structure and turnover, especially glycosaminoglycan (GAG) and proteoglycan biosynthesis and sulfation. Altogether, the gene expression analyses provide new insight into the consequences of FGFR3 mutations in cell cycle regulation, onset of pre-hypertrophic differentiation and concomitant metabolism changes. Moreover, impaired motility and ECM properties may also provide clues about growth plate disorganization. These results also suggest that many signaling pathways may be directly or indirectly altered by FGFR3 and confirm the crucial role of FGFR3 in the control of growth plate development.