Project description:New neurons are born throughout the life of mammals in germinal zones of the brain known as neurogenic niches: the subventricular zone of the lateral ventricles and the subgranular zone of the dentate gyrus of the hippocampus. These niches contain a subpopulation of cells known as adult neural progenitors (aNPCs), which self-renew and give rise to new neurons and glia. aNPCs are regulated by many factors present in the niche, including the extracellular matrix (ECM). We show that the neuropeptide PACAP (pituitary adenylate cyclase-activating polypeptide) affects subventricular zone-derived aNPCs by increasing their surface adhesion. Gene array and reconstitution assays indicate that this effect can be attributed to the regulation of ECM components and ECM-modifying enzymes in aNPCs by PACAP. Our work suggests that PACAP regulates a bidirectional interaction between the aNPCs and their niche: PACAP modifies ECM production and remodeling, in turn the ECM regulates progenitor cell adherence. We speculate that PACAP may in this manner help restrict adult neural progenitors to the stem cell niche in vivo, with potential significance for aNPC function in physiological and pathological states.
Project description:Primary human hepatocytes exhibit variable adhesiveness to culture vessels, which limits their utility in drug screening and regenerative medicine. We investigated the cause of this unstable adhesiveness of primary human hepatocytes and observed that the extracellular matrix on the surface inhibits cell adhesion to culture vessels. Elastin was identified as one of the main components of the surface extracellular matrix of non-adhering cells. This discovery suggests a novel approach to enhance their stable adhesion. Unstable adhesion of primary human hepatocytes to culture vessels significantly hinders their use in research. We discovered that extracellular matrix components on the cell surface inhibit their attachment. Specifically, we identified elastin as a key problematic component in non-adhering cells.
Project description:While investigating the causes of unstable adhesiveness of primary human hepatocytes, we observed that non-adhering cells had some kind of extracellular matrix on their surface, and this extracellular matrix inhibited cell adhesion to culture vessels. Removal of the matrix from the cell surface of non-adhering cells improved cellular attachment to culture vessels. We also performed comparative gene expression analysis between adhering and non-adhering cells to elucidate the molecular basis of differential adhesion behavior. We investigated the unstable adhesiveness of primary human hepatocytes and found that non-adhering cells had extracellular matrix on their surface that inhibited cell adhesion. We also observed that matrix removal improved cellular attachment.
Project description:<p>We sought to characterize cellular heterogeneity in the human cerebral cortex at a molecular level during cortical neurogenesis. We captured single cells and generated sequencing libraries using the C1TM Single-Cell Auto Prep System (Fluidigm), the SMARTer Ultra Low RNA Kit (Clontech), and the Nextera XT DNA Sample Preparation Kit (Illumina). We performed unbiased clustering of the single cells and further examined transcriptional variation among cell groups interpreted as radial glia. Within this population, the major sources of variation related to cell cycle progression and the stem cell niche from which radial glia were captured. We found that outer subventricular zone radial glia (oRG cells) preferentially express genes related to extracellular matrix formation, migration, and stemness, including <i>TNC</i>, <i>PTPRZ1</i>, <i>FAM107A</i>, <i>HOPX</i>, and <i>LIFR</i> and related this transcriptional state to the position, morphology, and cell behaviors previously used to classify the cell type. Our results suggest that oRG cells maintain the subventricular niche through local production of growth factors, potentiation of growth factor signals by extracellular matrix proteins, and activation of self-renewal pathways, thereby contributing to the developmental and evolutionary expansion of the human neocortex.</p> <p>For <b>study version 2</b>, we have updated this data set to include additional primary cells that we infer to represent microglia, endothelial cells, and immature astrocytes, as well as additional cells from the developing neural retina, and from iPS-cell derived cerebral organoids. The genes distinguishing these cell populations may reveal biological processes supporting the diverse functions of these cell types as well as vulnerabilities of specific cell types in human genetic diseases and in viral infections.</p> <p>For <b>study version 3</b>, we have updated the data set to include additional primary cells, including those published in Nowakowski, et al., Science 2017: "Spatiotemporal Gene Expression Trajectories Reveal Developmental Hierarchies of the Human Cortex" (<i>in press</i>)</p>
Project description:Many bacteria colonize surfaces and transition to a sessile mode of growth. The plant pathogen Agrobacterium tumefaciens produces a unipolar polysaccharide (UPP) adhesin at single cell poles that contact surfaces. Here we report that elevated levels of the intracellular signal cyclic diguanosine monophosphate (c-di-GMP) lead to surface-contact-independent UPP production and a red colony phenotype due to production of UPP and the exopolysaccharide cellulose, when A. tumefaciens is incubated with the polysaccharide stain Congo Red. Transposon mutations with elevated Congo Red staining identified presumptive UPP-negative regulators, mutants for which were hyperadherent, producing UPP irrespective of surface contact. Multiple independent mutations were obtained in visN and visR, activators of flagellar motility in A. tumefaciens, now found to inhibit UPP and cellulose production. Expression analysis in a visR mutant and isolation of suppressor mutations, identified three diguanylate cyclases inhibited by VisR. Null mutations for two of these genes decrease attachment and UPP production, but do not alter cellular c-di-GMP levels. However, analysis of catalytic site mutants revealed their GGDEF motifs are required to increase UPP production and surface attachment. Mutations in a specific presumptive c-di-GMP phosphodiesterase also elevate UPP production and attachment, consistent with c-di-GMP activation of surface-dependent adhesin deployment. Three biological replicates, independent RNA preparations, one dye swap.
Project description:Many bacteria colonize surfaces and transition to a sessile mode of growth. The plant pathogen Agrobacterium tumefaciens produces a unipolar polysaccharide (UPP) adhesin at single cell poles that contact surfaces. Here we report that elevated levels of the intracellular signal cyclic diguanosine monophosphate (c-di-GMP) lead to surface-contact-independent UPP production and a red colony phenotype due to production of UPP and the exopolysaccharide cellulose, when A. tumefaciens is incubated with the polysaccharide stain Congo Red. Transposon mutations with elevated Congo Red staining identified presumptive UPP-negative regulators, mutants for which were hyperadherent, producing UPP irrespective of surface contact. Multiple independent mutations were obtained in visN and visR, activators of flagellar motility in A. tumefaciens, now found to inhibit UPP and cellulose production. Expression analysis in a visR mutant and isolation of suppressor mutations, identified three diguanylate cyclases inhibited by VisR. Null mutations for two of these genes decrease attachment and UPP production, but do not alter cellular c-di-GMP levels. However, analysis of catalytic site mutants revealed their GGDEF motifs are required to increase UPP production and surface attachment. Mutations in a specific presumptive c-di-GMP phosphodiesterase also elevate UPP production and attachment, consistent with c-di-GMP activation of surface-dependent adhesin deployment.
Project description:Recently, our group has shown that the pituitary adenylate cyclase-activating polypeptide (PACAP)-induced neurite projection elongation in rat adrenal-derived pheochromocytoma cell line (PC12) is mediated via PAC1 receptor-mediated dephosphorylation of CRMP2 majorly through PI3K/AKT and MEK/ERK pathways. However, the mechanism of neuronal outgrowth by PACAP, including CRMP2 dephosphorylation, remains unclear. In our previous report, we found that GSK-3β, CDK5, and Rho/ROCK dephosphorylated CRMP2 within 3 hours after the addition of PACAP, but the early dephosphorylation of CRMP2 by PACAP remains unclear. Thus, we considered it important to identify early factors in PACAP-induced neurite projection elongation and performed omics-based transcriptomic (whole genome DNA microarray) and proteomic (TMT-labeling in conjunction with liquid chromatography-tandem mass spectrometry) analyses of gene and protein expression profiles from 5-120 minutes after PACAP addition. Results surprisingly revealed a number of key regulators involved in neurite outgrowth, including known ones. We also identified factors that may be involved in CRMP2 dephosphorylation. Cross-referencing previous research, we tried to map these molecular components onto potential pathways. The results of this comprehensive analysis may provide important new information on the molecular mechanisms of neuronal differentiation induced by PACAP.