scholarly journals Expression and functional studies of the GDNF family receptor alpha 3 in the pancreas

2015 ◽  
Vol 56 (2) ◽  
pp. 77-90 ◽  
Author(s):  
Laure Nivlet ◽  
Joel Herrmann ◽  
Delia Esteban Martin ◽  
Aline Meunier ◽  
Christophe Orvain ◽  
...  
Keyword(s):  
Islet Cell ◽  
Cell Formation ◽  
Cell Development ◽  
Β Cells ◽  
Receptor Alpha ◽  
Functional Studies ◽  
Factor Receptor Alpha ◽  
And Function ◽  
Deficient Mice

The generation of therapeutic β-cells from human pluripotent stem cells relies on the identification of growth factors that faithfully mimic pancreatic β-cell development in vitro. In this context, the aim of the study was to determine the expression and function of the glial cell line derived neurotrophic factor receptor alpha 3 (GFRα3) and its ligand artemin (Artn) in islet cell development and function. GFRα3 and Artn expression were characterized by in situ hybridization, immunochemistry, and qRT-PCR. We used GFRα3-deficient mice to study GFRα3 function and generated transgenic mice overexpressing Artn in the embryonic pancreas to study Artn function. We found that GFRα3 is expressed at the surface of a subset of Ngn3-positive endocrine progenitors as well as of embryonic α- and β-cells, while Artn is found in the pancreatic mesenchyme. Adult β-cells lack GFRα3 but α-cells express the receptor. GFRα3 was also found in parasympathetic and sympathetic intra-islet neurons as well as in glial cells in the embryonic and adult pancreas. The loss of GFRα3 or overexpression of Artn has no impact on Ngn3 and islet cell formation and maintenance in the embryo. Islet organization and innervation as well as glucose homeostasis is normal in GFRα3-deficient mice suggesting functional redundancy.

scholarly journals Altered Erythrocytes and a Leaky Block in B-Cell Development in CD24/HSA-Deficient Mice

Blood ◽  
1997 ◽  
Vol 89 (3) ◽  
pp. 1058-1067 ◽  
Author(s):  
P.J. Nielsen ◽  
B. Lorenz ◽  
A.M. Müller ◽  
R.H. Wenger ◽  
F. Brombacher ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
B Cell ◽  
Embryonic Stem ◽  
Cell Development ◽  
B Cell Development ◽  
Surface Glycoprotein ◽  
Malarial Parasite ◽  
Heat Stable Antigen ◽  
Deficient Mice

Abstract The heat stable antigen (HSA, or murine CD24) is a glycosyl phosphatidylinositol-linked surface glycoprotein expressed on immature cells of most, if not all, major hematopoietic lineages, as well as in developing neural and epithelial cells. It has been widely used to stage the maturation of B and T lymphocytes because it is strongly induced and then repressed again during their maturation. Terminally differentiated lymphocytes, as well as most myeloid lineages, are negative for HSA. Erythrocytes are an exception in that they maintain high levels of HSA expression. HSA on naive B cells has been shown to mediate cell-cell adhesion, while HSA on antigen-presenting cells has been shown to mediate a costimulatory signal important for activating T lymphocytes during an immune response. Here, we characterize mice that lack a functional HSA gene, constructed by homologous recombination in embryonic stem cells. While T-cell and myeloid development appears normal, these mice show a leaky block in B-cell development with a reduction in late pre-B and immature B-cell populations in the bone marrow. Nevertheless, peripheral B-cell numbers are normal and no impairment of immune function could be detected in these mice in a variety of immunization and infection models. We also observed that erythrocytes are altered in HSA-deficient mice. They show a higher tendency to aggregate and are more susceptible to hypotonic lysis in vitro. In vivo, the mean half-life of HSA-deficient erythrocytes was reduced. When infected with the malarial parasite Plasmodium chabaudi chabaudi, the levels of parasite-bearing erythrocytes in HSA-deficient mice were also significantly elevated, but the mice were able to clear the infection with kinetics similar to wild-type mice and were immune to a second challenge. Thus, apart from alterations in erythrocytes and a mild block in B-cell development, the regulated expression of HSA appears to be dispensable for the maturation and functioning of those cell lineages that normally express it.

scholarly journals PDGFRα: Expression and Function during Mitral Valve Morphogenesis

2021 ◽  
Vol 8 (3) ◽  
pp. 28
Author(s):  
Kelsey Moore ◽  
Diana Fulmer ◽  
Lilong Guo ◽  
Natalie Koren ◽  
Janiece Glover ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Primary Cilia ◽  
Growth Factor Receptor ◽  
Akt Phosphorylation ◽  
Valve Development ◽  
Biochemical Assays ◽  
Factor Receptor Alpha ◽  
Mesenchymal Transformation ◽  
And Function

Mitral valve prolapse (MVP) is a common form of valve disease and can lead to serious secondary complications. The recent identification of MVP causal mutations in primary cilia-related genes has prompted the investigation of cilia-mediated mechanisms of disease inception. Here, we investigate the role of platelet-derived growth factor receptor-alpha (PDGFRα), a receptor known to be present on the primary cilium, during valve development using genetically modified mice, biochemical assays, and high-resolution microscopy. While PDGFRα is expressed throughout the ciliated valve interstitium early in development, its expression becomes restricted on the valve endocardium by birth and through adulthood. Conditional ablation of Pdgfra with Nfatc1-enhancer Cre led to significantly enlarged and hypercellular anterior leaflets with disrupted endothelial adhesions, activated ERK1/2, and a dysregulated extracellular matrix. In vitro culture experiments confirmed a role in suppressing ERK1/2 activation while promoting AKT phosphorylation. These data suggest that PDGFRα functions to suppress mesenchymal transformation and disease phenotypes by stabilizing the valve endocardium through an AKT/ERK pathway.

Abstract 3: Il-10 Regulated Mir-375 Enhances Endothelial Progenitor Cell Mediated Myocardial Repair And Survival After Myocardial Infarction.

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Venkata N Garikipati ◽  
Prasanna Krishnamurthy ◽  
Suresh K Verma ◽  
Alexandra R Mackie ◽  
Erin E Vaughan ◽  
...  
Keyword(s):  
Capillary Density ◽  
Tube Formation ◽  
Lv Function ◽  
Myocardial Repair ◽  
Knock Down ◽  
Cardiac Functions ◽  
Dependent Protein ◽  
And Function ◽  
Deficient Mice

We hypothesized that IL-10 regulates miR-375 signaling in EPCs to enhance their survival and function in ischemic myocardium after MI. miR-375 knock down EPC were transplanted intramyocardially after induction of MI. Mice receiving EPC treated with miR-375 inhibitor showed increased number of GFP+EPCs retention that was associated with reduced EPC apoptosis in the myocardium. The engraftment of EPC into the vascular structures and the associated capillary density was significantly higher in miR-375-treated mice. The above findings further correlated with reduced infarct size, fibrosis and enhanced LV function (echocardiography) in miR-375 knock down EPC group as compared to scrambled EPC. Our in vitro studies revealed that the knockdown of miR-375 enhanced EPC proliferation, migration; tube formation ability and inhibited cell apoptosis, while the up-regulation of miR-375 with the mimic had the opposite effects. In addition, we found that miR-375 negatively regulates the expression of 3-phosphoinositide-dependent protein kinase 1 (PDK1) by directly targeting the 3'UTR of the PDK1 transcript. Interestingly, EPC isolated from IL-10-deficient mice has elevated basal levels of miR-375 and exhibited poor proliferation and tube formation ability where as miR-375 knock down in EPC isolated from IL-10 deficient mice attenuated these effects. Furthermore, transplantation of miR-375 knock down IL-10 deficient EPC after MI resulted in attenuated cardiac functions compared to scramble IL-10 deficient EPCs. Taken together, our studies suggest that IL-10 regulated miR-375 enhances EPC survival and function, associated with efficient myocardial repair via activation of PDK-1/AKT signaling cascades.

scholarly journals N-glycosylation critically regulates function of oxalate transporter SLC26A6

2016 ◽  
Vol 311 (6) ◽  
pp. C866-C873 ◽  
Author(s):  
R. Brent Thomson ◽  
Claire L. Thomson ◽  
Peter S. Aronson
Keyword(s):  
Plasma Membrane ◽  
Intestinal Secretion ◽  
Integral Membrane Proteins ◽  
Extracellular Loop ◽  
Transport Activity ◽  
Intact Cells ◽  
Functional Studies ◽  
And Function ◽  
Oxalate Transport

The brush border Cl−-oxalate exchanger SLC26A6 plays an essential role in mediating intestinal secretion of oxalate and is crucial for the maintenance of oxalate homeostasis and the prevention of hyperoxaluria and calcium oxalate nephrolithiasis. Previous in vitro studies have suggested that SLC26A6 is heavily N-glycosylated. N-linked glycosylation is known to critically affect folding, trafficking, and function in a wide variety of integral membrane proteins and could therefore potentially have a critical impact on SLC26A6 function and subsequent oxalate homeostasis. Through a series of enzymatic deglycosylation studies we confirmed that endogenously expressed mouse and human SLC26A6 are indeed glycosylated, that the oligosaccharides are principally attached via N-glycosidic linkage, and that there are tissue-specific differences in glycosylation. In vitro cell culture experiments were then used to elucidate the functional significance of the addition of the carbohydrate moieties. Biotinylation studies of SLC26A6 glycosylation mutants indicated that glycosylation is not essential for cell surface delivery of SLC26A6 but suggested that it may affect the efficacy with which it is trafficked and maintained in the plasma membrane. Functional studies of transfected SLC26A6 demonstrated that glycosylation at two sites in the putative second extracellular loop of SLC26A6 is critically important for chloride-dependent oxalate transport and that enzymatic deglycosylation of SLC26A6 expressed on the plasma membrane of intact cells strongly reduced oxalate transport activity. Taken together, these studies indicated that oxalate transport function of SLC26A6 is critically dependent on glycosylation and that exoglycosidase-mediated deglycosylation of SLC26A6 has the capacity to profoundly modulate SLC26A6 function.

scholarly journals Defective T cell development and function in calcineurin A -deficient mice

2002 ◽  
Vol 99 (14) ◽  
pp. 9398-9403 ◽  
Author(s):  
O. F. Bueno ◽  
E. B. Brandt ◽  
M. E. Rothenberg ◽  
J. D. Molkentin
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Calcineurin A ◽  
And Function ◽  
Deficient Mice

CD4+ Foxp3+ regulatory T cell-mediated immunomodulation by anti-depressants inhibiting acid sphingomyelinase

2018 ◽  
Vol 399 (10) ◽  
pp. 1175-1182 ◽  
Author(s):  
Jürgen Schneider-Schaulies ◽  
Niklas Beyersdorf
Keyword(s):  
T Cells ◽  
T Cell ◽  
Treg Cells ◽  
Tricyclic Antidepressant ◽  
Acid Sphingomyelinase ◽  
Human T Cells ◽  
And Function ◽  
Rate Limiting ◽  
Deficient Mice

AbstractAcid sphingomyelinase (ASM) is the rate-limiting enzyme cleaving sphingomyelin into ceramide and phosphorylcholin. CD4+Foxp3+regulatory T (Treg) cells depend on CD28 signaling for their survival and function, a receptor that activates the ASM. Both, basal and CD28-induced ASM activities are higher in Treg cells than in conventional CD4+T (Tconv) cells. In ASM-deficient (Smpd1−/−) as compared to wt mice, membranes of T cells contain 7–10-fold more sphingomyelin and two- to three-fold more ceramide, and are in a state of higher order than membranes of T cells from wt mice, which may facilitate their activation. Indeed, the frequency of Treg cells among CD4+T cells in ASM-deficient mice and their suppressive activityin vitroare increased. Moreover,in vitrostimulation of ASM-deficient T cells in the presence of TGF-β and IL-2 leads to higher numbers of induced Treg cells. Pharmacological inhibition of the ASM with a clinically used tricyclic antidepressant such as amitriptyline in mice or in tissue culture of murine or human T cells induces higher frequencies of Treg cells among CD4+T cells within a few days. This fast alteration of the balance between T cell populationsin vitrois due to the elevated cell death of Tconv cells and protection of the CD25highTreg cells by IL-2. Together, these findings suggest that ASM-inhibiting antidepressants, including a fraction of the serotonin re-uptake inhibitors (SSRIs), are moderately immunosuppressive and should be considered for the therapy of inflammatory and autoimmune disorders.

scholarly journals Transcript Lifetime Is Balanced between Stabilizing Stem-Loop Structures and Degradation-Promoting Polyadenylation in Plant Mitochondria

2001 ◽  
Vol 21 (3) ◽  
pp. 731-742 ◽  
Author(s):  
Josef Kuhn ◽  
Ulrike Tengler ◽  
Stefan Binder
Keyword(s):  
Plant Mitochondria ◽  
Rna Stability ◽  
Processing System ◽  
Stem Loop ◽  
Functional Studies ◽  
In Vitro Processing ◽  
Rapid Amplification ◽  
And Function

ABSTRACT To determine the influence of posttranscriptional modifications on 3′ end processing and RNA stability in plant mitochondria, peaatp9 and Oenothera atp1 transcripts were investigated for the presence and function of 3′ nonencoded nucleotides. A 3′ rapid amplification of cDNA ends approach initiated at oligo(dT)-adapter primers finds the expected poly(A) tails predominantly attached within the second stem or downstream of the double stem-loop structures at sites of previously mapped 3′ ends. Functional studies in a pea mitochondrial in vitro processing system reveal a rapid removal of the poly(A) tails up to termini at the stem-loop structure but little if any influence on further degradation of the RNA. In contrast 3′ poly(A) tracts at RNAs without such stem-loop structures significantly promote total degradation in vitro. To determine the in vivo identity of 3′ nonencoded nucleotides more accurately, pea atp9 transcripts were analyzed by a direct anchor primer ligation-reverse transcriptase PCR approach. This analysis identified maximally 3-nucleotide-long nonencoded extensions most frequently of adenosines combined with cytidines. Processing assays with substrates containing homopolymer stretches of different lengths showed that 10 or more adenosines accelerate RNA processivity, while 3 adenosines have no impact on RNA life span. Thus polyadenylation can generally stimulate the decay of RNAs, but processivity of degradation is almost annihilated by the stabilizing effect of the stem-loop structures. These antagonistic actions thus result in the efficient formation of 3′ processed and stable transcripts.

scholarly journals Effective In Vitro Clearance ofPorphyromonas gingivalis by Fcα Receptor I (CD89) on Gingival Crevicular Neutrophils

2001 ◽  
Vol 69 (5) ◽  
pp. 2935-2942 ◽  
Author(s):  
Tetsuo Kobayashi ◽  
Kouji Yamamoto ◽  
Noriko Sugita ◽  
Annemiek B. van Spriel ◽  
Susumu Kaneko ◽  
...  
Keyword(s):  
Gingival Crevicular Fluid ◽  
Polymorphonuclear Neutrophils ◽  
Causative Pathogen ◽  
Effector Functions ◽  
Functional Studies ◽  
Candidate Target ◽  
Optimal Target ◽  
Crevicular Fluid ◽  
And Function

ABSTRACT Porphyromonas gingivalis has been implicated as a causative pathogen in periodontitis. Immunotherapeutic approaches have recently been suggested to aid in the clearance of P. gingivalis from disease sites. Because antibody-Fc receptor (FcR) interactions play a role in the effector functions of polymorphonuclear neutrophils (PMN), we evaluated which FcR on PMN from gingival crevicular fluid (GCF) serves as an optimal target molecule for FcR-directed immunotherapy. GCF PMN and peripheral blood (PB) PMN from adult periodontitis patients were analyzed for their immunoglobulin G (IgG) and IgA FcR (FcγR and FcαR, respectively) expression and function by studying IgG- and IgA-mediated elimination of P. gingivalis. GCF PMN exhibited higher FcαRI and FcγRI levels and lower FcγRIIa and FcγRIIIb levels than PB PMN. Functional studies revealed that GCF PMN exhibited less of a capacity to phagocytose and kill IgG1-opsonized P. gingivalisthan PB PMN. IgA1-mediated phagocytosis and killing capacity was, however, comparable between GCF PMN and PB PMN. In summary, these in vitro results document that FcαRI represents a candidate target for FcR-directed immunotherapy for the clearance of P. gingivalis.

scholarly journals Iκb Kinase α Is Essential for Mature B Cell Development and Function

2001 ◽  
Vol 193 (4) ◽  
pp. 417-426 ◽  
Author(s):  
Tsuneyasu Kaisho ◽  
Kiyoshi Takeda ◽  
Tohru Tsujimura ◽  
Taro Kawai ◽  
Fumiko Nomura ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Fetal Liver ◽  
Cell Development ◽  
B Cell Development ◽  
Cytokine Signaling ◽  
Iκb Kinase ◽  
And Function

IκB kinase (IKK) α and β phosphorylate IκB proteins and activate the transcription factor, nuclear factor (NF)-κB. Although both are highly homologous kinases, gene targeting experiments revealed their differential roles in vivo. IKKα is involved in skin and limb morphogenesis, whereas IKKβ is essential for cytokine signaling. To elucidate in vivo roles of IKKα in hematopoietic cells, we have generated bone marrow chimeras by transferring control and IKKα-deficient fetal liver cells. The mature B cell population was decreased in IKKα−/− chimeras. IKKα−/− chimeras also exhibited a decrease of serum immunoglobulin basal level and impaired antigen-specific immune responses. Histologically, they also manifested marked disruption of germinal center formation and splenic microarchitectures that depend on mature B cells. IKKα−/− B cells not only showed impairment of survival and mitogenic responses in vitro, accompanied by decreased, although inducible, NF-κB activity, but also increased turnover rate in vivo. In addition, transgene expression of bcl-2 could only partially rescue impaired B cell development in IKKα−/− chimeras. Taken together, these results demonstrate that IKKα is critically involved in the prevention of cell death and functional development of mature B cells.

Sign in / Sign up

Export Citation Format

Share Document