Project description:By chemical modulation of the PKA/CREB and BMP pathways in isolated AGM VE-cadherin+ cells from mid-gestation embryos, we demonstrate that PKA/CREB regulates hematopoietic engraftment and clonogenicity of hematopoietic progenitors and is dependent on secreted BMP ligands through the type I BMP receptor. We used microarray to document upregulation of PKA/CREB-BMP pathway as well as global BMP target upregulation upon PKA/CREB activation. Isolated VE+ cells from E11.5 AGM were treated with BMP4 (4ng/ml), forskolin (25uM) or both for 8 hours before RNA isolation.
Project description:By chemical modulation of the PKA/CREB and BMP pathways in isolated AGM VE-cadherin+ cells from mid-gestation embryos, we demonstrate that PKA/CREB regulates hematopoietic engraftment and clonogenicity of hematopoietic progenitors and is dependent on secreted BMP ligands through the type I BMP receptor. We used microarray to document upregulation of PKA/CREB-BMP pathway as well as global BMP target upregulation upon PKA/CREB activation.
Project description:Blood flow promotes emergence of definitive hematopoietic stem cells (HSCs) in the developing embryo, yet the signals generated by hemodynamic forces that influence hematopoietic potential remain poorly defined. In transplantation assays of hematopoietic reconstitution, we find that fluid shear stress endows long-term multilineage engraftment potential upon early hematopoietic tissues at E9.5 not previously described to harbor HSCs. Effects on hematopoiesis appear to be mediated in part by prostaglandin E2 (PGE2) and the cyclic AMP-protein kinase A (cAMP-PKA) signaling axis. Studies of Ncx1 cardiac mutants corroborate that blood flow is required for sufficient COX2 levels and phosphorylation of CREB. Further implicating PGE2 in mediating the effects of shear stress, we find that E10.5 and E11.5 AGM treated transiently with the synthetic analog dmPGE2 engraft more robustly and contribute to greater lymphoid reconstitution. These data provide a mechanism by which biomechanical forces induced by blood flow modulate hematopoietic potential. -
Project description:A mouse AGM-derived cell line, AGM-s3, was shown to support the development of hematopoietic stem cells. To elucidate the molecular mechanisms regulating early hematopoiesis, we obtained subclones from AGM-s3, some of which were hematopoiesis supportive (s3-A9) and others which were non-supportive (s3-A7), and we analyzed the gene expression profiles by gene chip analysis. Experiment Overall Design: Genome-wide gene expression was examined using Affymetrix GeneChip array. Assays were performed according to the manufacturer's protocol. Total RNA was isolated from each stromal cell lines. We analysed 3 cell lines, AGM-s3-A9, AGM-s3-A7 and OP9. AGM-s3-A9 and OP9 are hematopoiesis supportive cell lines. AGM-s3-A7 is a hematopoiesis non-supportive cell line.
Project description:Blood flow promotes emergence of definitive hematopoietic stem cells (HSCs) in the developing embryo, yet the signals generated by hemodynamic forces that influence hematopoietic potential remain poorly defined. In transplantation assays of hematopoietic reconstitution, we find that fluid shear stress endows long-term multilineage engraftment potential upon early hematopoietic tissues at E9.5 not previously described to harbor HSCs. Effects on hematopoiesis appear to be mediated in part by prostaglandin E2 (PGE2) and the cyclic AMP-protein kinase A (cAMP-PKA) signaling axis. Studies of Ncx1 cardiac mutants corroborate that blood flow is required for sufficient COX2 levels and phosphorylation of CREB. Further implicating PGE2 in mediating the effects of shear stress, we find that E10.5 and E11.5 AGM treated transiently with the synthetic analog dmPGE2 engraft more robustly and contribute to greater lymphoid reconstitution. These data provide a mechanism by which biomechanical forces induced by blood flow modulate hematopoietic potential. - AGM from C57BL/6J embryos at 10.5 days gestation (E10.5) were isolated by microdissection from uteri of pregnant dams, following by gentle dissociation by Accutase with agitation at room temperature for 20 minutes. Single cell suspension was seeded on microfluidic IBIDI VI^0.4 6-channel slides (0.8 to 1x10^7 cells per channel) and permitted to attach for 8 hours. Fluid movement was then applied to each channel using a Harvard Apparatus PHD ULTRA programmable syringe pump for manangement of M5300 Myelocult medium. Cells were exposed either to static/low flow (0.0001 dyne/cm^2) or wall shear stress (WSS) of 5 dyne/cm^2 for 6 hours or 36 hours. In addition, some cells were treated with 10 uM indomethacin (indo) to inhibit COX2 activity and PGE2 synthesis. Upon collection of cells with RLT lysis buffer (QIAGEN RNeasy kit), six channels of identical treatment were pooled to comprise a single sample. 24 samples total are included in this study. 12 samples were collected after 6 hours and 12 after 36 hours. In detail, samples included at 6 hours: 3 static, 3 static with indo, 3 WSS, 3 WSS with indo; and at 36 hours: 3 static, 3 static with indo, 3 WSS, 3 WSS with indo. Sample labels begin with the timepoint collected and end with the replicate number, i.e., 06WSS1 for the 6 hour collection of the first replicate of the WSS sample.
Project description:The first HSCs are produced in the aorta-gonadmesonephros (AGM) region of the embryo through endothelial to a hematopoietic transition. BMP4 and Hedgehog affect their production/expansion, but it is unknown whether they act to affect the same HSCs. In this study using the BRE GFP reporter mouse strain that identifies BMP/Smad-activated cells, we find that the AGM harbors two types of adult-repopulating HSCs upon explant culture. Embryonic day 11 AGM are dissected and either analyzed directly, or after explant culture in conditions containing BMP/Hedgehog with or without cyclopamine. EC: endothelial enriched (CD31+Kit-); MC: mesenchymal cell enriched (CD31-Kit-); HPSC: hematopoietic progenitor/stem cell enriched; AGM11: E11 fresh AGMs; AGMex: AGM after explant culture; AGMcy: AGM after explant in presence of cyclopamine; CD31p: CD31 positive; CD31n: CD31 negative; KITp: c-Kit positive; KITn: c-Kit negative; BREp: BRE-GFP positive; BREn: BRE-GFP negative
Project description:Myofiber size regulation is critical in health, disease, and aging. MuSK (muscle-specific kinase) is a BMP (bone morphogenetic protein) co-receptor that promotes and shapes BMP signaling that is expressed at all neuromuscular junctions and is also present extrasynaptically in the slow soleus muscle. To investigate the role of the MuSK-BMP pathway in vivo we generated mice lacking the BMP-binding MuSK Ig3 domain. These ∆Ig3-MuSK mice are viable and fertile with innervation levels comparable to wild type. In 3-month-old mice myofibers are smaller in the slow soleus, but not in the fast TA. Here we use bulk RNA-seq to perform transcriptomic analysis of slow and fast mouse muscle. RNAseq analysis revealed soleus-selective decreases in RNA metabolism and protein synthesis pathways as well as dysregulation of IGF1 pathway components. Moreover, Akt-mTOR signaling is reduced in soleus but not TA. We propose that the MuSK-BMP pathway acts extrasynaptically to maintain myofiber size in slow muscle by promoting protein synthetic pathways including the IGF1-Akt-mTOR signaling. These results reveal a novel mechanism for regulating myofiber size in slow muscle and introduce the MuSK-BMP pathway as a target for promoting muscle growth and combatting atrophy.
Project description:A mouse AGM-derived cell line, AGM-s3, was shown to support the development of hematopoietic stem cells. To elucidate the molecular mechanisms regulating early hematopoiesis, we obtained subclones from AGM-s3, some of which were hematopoiesis supportive (s3-A9) and others which were non-supportive (s3-A7), and we analyzed the gene expression profiles by gene chip analysis. Keywords: cell type comparison
Project description:Xenopus embryonic ectodermal cells are responsive to various inducing factors. Mesoderm is specified and patterned by extracellular factors including FGF, Nodal, BMP and Wnt families. Pinhead is another secreted protein implicated in mesoderm formation. We found that Pinhead physically interacts with and antagonizes ADMP (anti-dorsalizing morphogenetic protein) that acts as BMP-like protein to promote ventral mesoderm formation. ADMP and BMPs have been shown to cooperate to activate phospho-Smad1 signaling to lead to ventral mesoderm development. Since Chordin is a BMP antagonist, we hypothesized that Pinhead together with Chordin can promote downregulation of phospho-Smad1 signaling that leads to dorsal mesoderm development. RNA sequencing revealed that Pinhead and Chordin synergize in dorsal mesoderm formation in ectodermal explants.
Project description:Although persistent elevations in circulating glucose concentrations promote compensatory increases in pancreatic islet mass, unremitting insulin resistance causes a deterioration in beta cell function that disrupts glucose balance and signals the progression to diabetes 1. Glucagon like Peptide 1 (GLP1) agonists improve glucose tolerance in insulin resistance, although some individuals are unresponsive to treatment. Here we show that increases in GLP1 during feeding promote beta cell function in part through the PKA-mediated activation of CREB and its coactivator CRTC2 2. Mice with a knockout of CRTC2 in beta cells have impaired oral glucose tolerance due to decreases in circulating insulin concentrations. CRTC2 was found to promote beta cell function in part by stimulating the expression of the transcription factor MafA. Chronic hyperglycemia associated with high fat or high carbohydrate diet feeding disrupted cAMP signaling in pancreatic islets. Indeed, prolonged elevations in circulating glucose concentrations interfered with CREB signaling by activating the mTOR pathway and triggering the hypoxia inducible factor (HIF1)-dependent induction of the Protein Kinase A Inhibitor beta (PKIB), a potent inhibitor of PKA catalytic activity 3. As disruption of the PKIB gene restored glucose tolerance and insulin secretion in obesity, our results demonstrate how cross-talk between nutrient and hormonal pathways contributes to loss of pancreatic islet function in insulin resistance. Rat insulinoma cells were used to interrogate the impact of glucose exposure and CREB activity on cAMP dependent gene regulation in the pancreatic beta cells