Project description:The nuclear membrane protein SUN1 promotes blood vessel formation and barrier function by stabilizing endothelial cell-cell junctions. Communication between SUN1 and endothelial cell junctions relies upon proper microtubule dynamics and Rho signaling, revealing long-range cellular communication from the nucleus to the cell periphery that is important for vascular development and function.
Project description:This study was conducted to analyze phenotypic and proteomic differences of two Lactiplantibacillus plantarum strains (WCFS1, model strain from human saliva, and CIP104448, stool isolate) when a biofilm was produced under static conditions (well researched), or with the addition of flow (novel).
Project description:SUN1 was identified in a screen for fertility genes in Plasmodium berghei. To understand its role, SUN1 was tagged with an HA tag at the endogenous locus, and SUN1 interacting proteins were characterised by affinity purification followed by mass spectrometry. This led to the identification of allantoicase as a SUN1-associated protein. Subsequent affinity interaction proteomics of HA-tagged allantoicase confirmed the interaction between these two proteins.
Project description:The inner nuclear envelope (NE) proteins interact with the nuclear lamina and participate in the architectural compartmentalization of chromosomes. The association of NE proteins with DNA contributes to the spatial rearrangement of chromosomes and their gene expression. Sun1 is an inner nuclear membrane (INM) protein that locates to telomeres and anchors chromosome movement in the prophase of meiosis. Here, we have created Sun1-/- mice and found that these mice are born and grow normally but are reproductively infertile. Detailed molecular analyses showed that Sun1-/- P14 testes are repressed for the expression of reproductive genes and have no detectable piRNA. These findings raise a heretofore unrecognized role of Sun1 in the selective gene expression of coding and non-coding RNAs needed for gemetogenesis. Total RNA was isolated from E14.5 mouse embryonic fibroblasts (MEFs) and and day 9 and 14 mouse whole testes. cDNA samples from paired (same parents) wt (Cy3-labled) and Sun1-/- (Cy5-labled) mice were mixed and hybridized.
Project description:d9 and d12 Mks were either cultured statically or subjected to shear flow for 30 min; at d9, half the Mks were placed back in culture for 30 min (60 min time point) Megakaryocytes (Mks) are exposed to shear flow as they migrate from the bone marrow hematopoietic compartment into circulation thus releasing platelets and pro/preplatelets directly into the blood stream. Shear forces have been now established as promoting Mk maturation and platelet biogenesis. In order to understand the underlying mechanisms that modulate the response of Mks to shear forces, we carried out transcriptional analysis on immature and mature stem cell-derived Mks that were exposed to physiologically-relevant shear (2.5 dyn/cm2). In immature (d9) Mks, shear exposure upregulated genes related to growth and Mk maturation, while in mature (d12) Mks, it upregulated genes involved in apoptosis and intracellular transport. Following shear-flow exposure, 6 AP-1 transcripts (ATF4, JUNB, JUN, FOSB, FOS, and JUND) were upregulated at d9 and two AP-1 proteins (JunD and c-Fos) were upregulated both at d9 and d12. Our data show that MAPK signaling is linked to both the shear-stress response and AP-1 upregulation. JNK phosphorylation increased significantly following shear stimulation, while JNK inhibition reduced shear-induced JunD protein expression. Although p38 phosphorylation did not increase following shear flow, its inhibition reduced shear-induced JunD and c-Fos protein expression. JNK inhibition reduced fibrinogen binding of d9 and d12 platelet-like particle s (PLPs) and P-selectin expression at d12 PLPs, while p38 inhibition reduced fibrinogen binding of d12 PLPs. Here we show that mechanotransduction of shear forces in Mks results in JNK activation, AP-1 upregulation, and downstream transcriptional changes that promote maturation of immature Mks and platelet biogenesis in mature Mks. Two- and Three-condition experiment (flow vs. static culture condition, d9 vs. d12, and 30 min vs. 60 min at d9); Biological replicates: 3; Technical replicates: 1 (dye-swap)
Project description:Extracellular vesicles released by tumors (tEVs) disseminate via circulatory networks and promote microenvironmental changes in distant organs favoring metastatic seeding. Despite their abundance in the bloodstream, how hemodynamics affect the function of circulating tEVs remains unsolved. We experimentally tuned flow profiles in vitro (microfluidics) and in vivo (zebrafish) and demonstrated that efficient uptake of tEVs occurs in endothelial cells subjected to capillary-like hemodynamics. Such flow profiles partially reroute internalized tEVs towards non-acidic and non-degradative Rab14-positive endosomes, at the expense of lysosomes, suggesting that endothelial mechanosensing diverts tEVs from degradation. Subsequently, tEVs promote the expression of pro-angiogenic transcription factors in flow-stimulated endothelial cells and favor vessel sprouting in zebrafish. Altogether, we demonstrate that capillary-like flow profiles potentiate the pro-tumoral function of circulating tEVs by promoting their uptake and rerouting their trafficking. We propose that tEVs contribute to pre-metastatic niche formation by exploiting endothelial mechanosensing in specific vascular regions with permissive hemodynamics. This set of experiments represents RNAseq of HUVEC cells subjected to 400 µm/s flow versus no flow (static conditon).
Project description:We expressed a constitutively active mutant of MEK5 (MEK5D) in human primary endothelial cells (EC) to study the transcriptional and functional responses to Erk5 activation under static conditions. HUVEC were infected with either empty vector or constitutively active MEK5D and RNA was processed for microarray analysis 40 h post infection.
Project description:Mesenchyal Stem Cells (MSCs) differentiation into multiple lineages, such as osteocytes and adipocytes, has been shown to be regulated by mechanical signals. The Linker of the Nucleoskeleton and Cytoskeleton (LINC) complex has been shown to be required for mechanical signal transduction, regulation of MSCs differentiation, and nuclear integrity. The LINC complex is made of Nesprins and Sun proteins. Nesprin proteins associate with the cytoskeleton on the outer nuclear membrane and Sun proteins are bound to the inner nuclear membrane where they bind to inner nuclear proteins and chromatin. We investigated the role of the Sun1/2 in regulating the inner nuclear functions of chromatin organization and adipogenic differentiation independently of the LINC complex function. We show that depletion of Sun1/2 increased nuclear area and perimeter, and decreased circularity. Expression of a dominant-negative KASH (dnKASH) domain targeting the SUN domain on Sun proteins inhibiting Nesprin-SUN association resulting a loss of Nesprin localization to the nuclear envelope decreased nuclear area and circularity. Adipogenesis was inhibited during Sun1/2 depletion while dnKASH expression accelerated adipgoenesis. RNA-seq data showed decreased adipogensis and increased immune response during Sun1/2 depletion. dnKASH responded oppositely with increased adipogenic gene expression and decreased immune response. We also observed increased H3K9me3 levels, increased H3K9me3 foci count, and enrichment on Adipoq during Sun1/2 depletion. No increase of H3K9me3 levels, foci count, or increased H3K9me3 enrichment on Adipoq was found during dnKASH expression. We conclude that physically decoupling of the LINC complex via dnKASH accelerates adipogenesis and that Sun1/2 regulates chromatin organization and adipogenesis independently of the LINC complex function.
Project description:The inner nuclear envelope (NE) proteins interact with the nuclear lamina and participate in the architectural compartmentalization of chromosomes. The association of NE proteins with DNA contributes to the spatial rearrangement of chromosomes and their gene expression. Sun1 is an inner nuclear membrane (INM) protein that locates to telomeres and anchors chromosome movement in the prophase of meiosis. Here, we have created Sun1-/- mice and found that these mice are born and grow normally but are reproductively infertile. Detailed molecular analyses showed that Sun1-/- P14 testes are repressed for the expression of reproductive genes and have no detectable piRNA. These findings raise a heretofore unrecognized role of Sun1 in the selective gene expression of coding and non-coding RNAs needed for gemetogenesis.
Project description:Chromosomes pair and synapse with their homologous partners to segregate correctly at meiosis I. Association of telomeres with the LINC (Linker of Nucleoskeleton and Cytoskeleton) complex enables telomere-led chromosome movements and telomere bouquet formation, facilitating precise pairwise alignment of homologs. Here, we identify a direct interaction between SUN1 and Speedy A (SPDYA) and determine the crystal structure of human SUN1-SPDYA-CDK2 ternary complex. Analysis of meiosis prophase I process in SPDYA-binding-deficient SUN1 mutant mice reveals that the SUN1-SPDYA interaction is required for the telomere-LINC complex connection and the assembly of a ring-shaped telomere supramolecular architecture at the nuclear envelope, which is critical for efficient homologous pairing and synapsis. Overall, our results provide structural insights into meiotic telomere structure that is essential for meiotic prophase progression.