1
|
Nham GTH, Zhang X, Asou Y, Shinomura T. Expression of type II collagen and aggrecan genes is regulated through distinct epigenetic modifications of their multiple enhancer elements. Gene 2019; 704:134-141. [DOI: 10.1016/j.gene.2019.04.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 04/03/2019] [Accepted: 04/10/2019] [Indexed: 12/31/2022]
|
2
|
Chen JS, Chen YH, Huang PH, Tsai HY, Chen YL, Lin SJ, Chen JW. Ginkgo biloba extract reduces high-glucose-induced endothelial adhesion by inhibiting the redox-dependent interleukin-6 pathways. Cardiovasc Diabetol 2012; 11:49. [PMID: 22553973 PMCID: PMC3434011 DOI: 10.1186/1475-2840-11-49] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 05/03/2012] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Chronic elevation of glucose level activates vascular inflammation and increases endothelial adhesiveness to monocytes, an early sign of atherogenesis. This study aimed to elucidate the detailed mechanisms of high-glucose-induced endothelial inflammation, and to investigate the potential effects of Ginkgo biloba extract (GBE), an antioxidant herbal medicine, on such inflammation. MATERIALS AND METHODS Human aortic endothelial cells were cultured in high glucose or mannitol as osmotic control for 4 days. The expression of cytokines and adhesion molecules and the adhesiveness of endothelial cells to monocytes were examined. The effects of pretreatment of GBE or N-acetylcysteine, an antioxidant, were also investigated. RESULTS Either high glucose or mannitol significantly increased reactive oxygen species (ROS) production, interleukin-6 secretion, intercellular adhesion molecule-1 (ICAM-1) expression, as well as endothelial adhesiveness to monocytes. The high-glucose-induced endothelial adhesiveness was significantly reduced either by an anti-ICAM-1 antibody or by an interleukin-6 neutralizing antibody. Interleukin-6 (5 ng/ml) significantly increased endothelial ICAM-1 expression. Piceatannol, a signal transducer and activator of transcription (STAT) 1/3 inhibitor, but not fludarabine, a STAT1 inhibitor, suppressed high-glucose-induced ICAM-1 expression. Pretreatment with GBE or N-acetylcysteine inhibited high-glucose-induced ROS, interleukin-6 production, STAT1/3 activation, ICAM-1 expression, and endothelial adhesiveness to monocytes. CONCLUSIONS Long-term presence of high glucose induced STAT3 mediated ICAM-1 dependent endothelial adhesiveness to monocytes via the osmotic-related redox-dependent interleukin-6 pathways. GBE reduced high-glucose-induced endothelial inflammation mainly by inhibiting interleukin-6 activation. Future study is indicated to validate the antioxidant/anti-inflammatory strategy targeting on interleukin-6 for endothelial protection in in vivo and clinical hyperglycemia.
Collapse
Affiliation(s)
- Jia-Shiong Chen
- Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan, Republic of China
| | | | | | | | | | | | | |
Collapse
|
3
|
Modulation of Cx43 and Gap Junctional Intercellular Communication by Androstenedione in Rat Polycystic Ovary and Granulosa Cells in vitro. J Reprod Infertil 2012; 13:21-32. [PMID: 23926521 PMCID: PMC3719373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 12/03/2011] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND Gap-junctional intercellular communication (GJIC) is implicated in physicological processes and it is vitally important for granulosa cell (GC) differentiation and oocyte growth. We investigated the expression of connexin 43 (Cx43), a gap junctional protein, in normal and androstenedione-induced polycystic ovary (PCO), the effects of androstenedione on Cx43 expression, GJIC and progesterone production in granulosa cells in vitro. METHODS Isolated GCs from rat ovary were supplemented with FSH and dripped with EHS-matrix (EHS-drip) in culture media, were treated with physiological (10(-7) M) or pathological (10(-5) M) androstenedione concentrations to induce differentiation. Cx43 protein levels were assessed by Western blotting. Immunohistochemistry was also used to determine the localization of Cx43 in GCs and corpus luteum (CL) of controls and PCOs. Differentiation of GCs was determined by progesterone assay and Lucifer yellow dye transfer for GJIC status. The degree of significance of variations between the results was analyzed by ANOVA using SPSS (version 11.5; 2002). RESULTS Cx43 localized in the GC layer of both the control and PCOs. Its protein levels were upregulated in PCO rat ovaries. GCs in culture with or without androstenedione had a punctate membranous distribution of Cx43. However, androstenedione increased GJIC and upregulated progesterone and Cx43 protein levels. Inhibiting GJIC by 18-α GA in androstenedione-treated GCs caused partial inhibition of progesterone production, suggesting a possible role of GJIC in mediating the action of androstenedione on GC differentiation. CONCLUSION This study presented a suitable culture model for polycystic ovary syndrome and showed that Cx43 and GJIC might contribute to the pathogenesis of polycystic ovary syndrome.
Collapse
|
4
|
Collison DJ, Tovell VE, Coombes LJ, Duncan G, Sanderson J. Potentiation of ATP-induced Ca2+ mobilisation in human retinal pigment epithelial cells. Exp Eye Res 2005; 80:465-75. [PMID: 15781274 DOI: 10.1016/j.exer.2004.09.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Accepted: 09/21/2004] [Indexed: 11/17/2022]
Abstract
Interaction of signalling pathways directs the functional output of many cells. This study investigated the consequences of activating adenosine and adrenergic receptors on ATP-induced Ca2+ responses in human retinal pigment epithelial (RPE) cells. Intracellular Ca2+ concentration ([Ca2+]i) of human RPE cells in primary culture was monitored using Fura-2. Cyclic adenosine monophosphate (cAMP) concentration was measured using an enzyme-linked immunosorbent assay. Both ATP and UTP (10 microM) increased [Ca2+]i in human RPE cells. Adenosine (10 nM-10 microM) had no effect on resting [Ca2+]i, but potentiated a sub-threshold response to ATP (100 nM) when ATP was added in the presence of adenosine. The potentiation occurred with other G-protein receptor agonists such as acetylcholine. Potentiation persisted in Ca-free medium, but was blocked by prior application of thapsigargin. The A1 and A2 adenosine receptor antagonists, DPCPX and MRS1706 (100 nM) respectively, inhibited potentiation in 76+/-7 and 23+/-12% of cells, respectively, but the A3 antagonist MRS1191 had no effect. Conversely, agents that activate the cAMP pathway, including isoproterenol (10 microM), forskolin (10 microM), and the protein kinase A (PKA) activator Sp-cBIMPS (1 microM), potentiated the ATP-induced response in the RPE cells. Agents that are known to inhibit the production of cAMP in other systems also caused potentiation, including clonidine (10 microM) and the Gi-activator mastoparan (10 microM). Under resting conditions, cAMP concentration in RPE cells was 7.1+/-0.5 pmol mg(-1) protein. Isoproterenol (10 microM) and forskolin (10 microM) increased levels to 104.6+/-5.2 and 113.7+/-4.2 pmol mg(-1) protein, respectively, while adenosine, clonidine, and mastoparan (all 10 microM) had no significant effect on cAMP levels. These data indicate that whilst activation of A1 and A2 adenosine receptors and alpha2 and beta adrenergic receptors does not influence basal Ca2+ levels, stimulation of these receptors can potentiate Ca2+ signalling by cAMP dependent and independent mechanisms in human RPE cells.
Collapse
Affiliation(s)
- David J Collison
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
| | | | | | | | | |
Collapse
|
5
|
Evans JF, Niu QT, Canas JA, Shen CL, Aloia JF, Yeh JK. ACTH enhances chondrogenesis in multipotential progenitor cells and matrix production in chondrocytes. Bone 2004; 35:96-107. [PMID: 15207745 DOI: 10.1016/j.bone.2004.03.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Revised: 03/11/2004] [Accepted: 03/16/2004] [Indexed: 11/25/2022]
Abstract
The association of melanocortin peptide overproduction with enhanced linear growth prompted the current investigation of adrenocorticotropin hormone (ACTH) effects on multipotential chondroprogenitor populations and committed chondrocytes in culture. Two multipotential progenitor populations, rat bone marrow stromal cells (BMSC) and the clonal multipotential cell line RCJ3.1, and two committed chondrocyte populations, resting chondrocytes (RC) isolated from the rib of young rats and the chondrocyte restricted cell line RCJ3.1C5.18 (C5.18), were cultured in differentiation medium plus or minus ACTH. Alcian blue stain was used to quantitate proteoglycan matrix production in all populations treated with a range of ACTH concentrations. Changes in proliferation due to ACTH treatment of all cell types were measured using 3H-thymidine incorporation. Differences in matrix production of ACTH-treated and -untreated RC and C5.18 cells were determined using 3H-proline incorporation. Relative transcript expression of the chondrocyte matrix proteins collagen type II (COLL II) and aggrecan (AGR) in treated and untreated cells was analyzed by Northern blot. Collagen type X (COLL X), a marker of hypertrophic differentiation, was measured in committed chondrocytic populations. Western analysis was used to detect the melanocortin-3 receptor (MC3-R), which was a suspected mediator of the ACTH signal. Matrix deposition was dose-dependently increased by ACTH in all cell populations as measured by alcian blue stain. ACTH treatment increased proliferation in multipotential progenitor populations (BMSC and RCJ3.1) while proliferation was decreased in committed chondrocyte populations (RC and C5.18). Total protein and total cell-associated collagen production were significantly increased by ACTH treatment in committed populations. Relative COLL II and AGR transcript expressions were significantly increased in both the RC- and C5.18-committed population and very significantly increased in the progenitor populations. Additionally, collagen type X expression was detected earlier and in greater abundance in ACTH-treated committed chondrocyte populations. Finally, the melanocortin-3 receptor was detected in all examined cell types by Western blot. These data show that ACTH promotes the development of the chondrocyte phenotype from multipotential mesenchymal progenitor populations and increases matrix production and differentiation of committed chondrocytes. These findings, together with the detection of the MC3-R in all of these cell types, indicate a role for the melanocortin system in chondrogenesis.
Collapse
Affiliation(s)
- Jodi F Evans
- Department of Medicine, Winthrop University Hospital, Mineola, NY 11501, USA.
| | | | | | | | | | | |
Collapse
|
6
|
Werry TD, Wilkinson GF, Willars GB. Mechanisms of cross-talk between G-protein-coupled receptors resulting in enhanced release of intracellular Ca2+. Biochem J 2003; 374:281-96. [PMID: 12790797 PMCID: PMC1223610 DOI: 10.1042/bj20030312] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2003] [Revised: 06/03/2003] [Accepted: 06/05/2003] [Indexed: 12/21/2022]
Abstract
Alteration in [Ca(2+)](i) (the intracellular concentration of Ca(2+)) is a key regulator of many cellular processes. To allow precise regulation of [Ca(2+)](i) and a diversity of signalling by this ion, cells possess many mechanisms by which they are able to control [Ca(2+)](i) both globally and at the subcellular level. Among these are many members of the superfamily of GPCRs (G-protein-coupled receptors), which are characterized by the presence of seven transmembrane domains. Typically, those receptors able to activate PLC (phospholipase C) enzymes cause release of Ca(2+) from intracellular stores and influence Ca(2+) entry across the plasma membrane. It has been well documented that Ca(2+) signalling by one type of GPCR can be influenced by stimulation of a different type of GPCR. Indeed, many studies have demonstrated heterologous desensitization between two different PLC-coupled GPCRs. This is not surprising, given our current understanding of negative-feedback regulation and the likely shared components of the signalling pathway. However, there are also many documented examples of interactions between GPCRs, often coupling preferentially to different signalling pathways, which result in a potentiation of Ca(2+) signalling. Such interactions have important implications for both the control of cell function and the interpretation of in vitro cell-based assays. However, there is currently no single mechanism that adequately accounts for all examples of this type of cross-talk. Indeed, many studies either have not addressed this issue or have been unable to determine the mechanism(s) involved. This review seeks to explore a range of possible mechanisms to convey their potential diversity and to provide a basis for further experimental investigation.
Collapse
Affiliation(s)
- Tim D Werry
- Department of Cell Physiology and Pharmacology, Medical Sciences Building, University of Leicester, UK
| | | | | |
Collapse
|
7
|
Leaver EV, Pappone PA. Beta-adrenergic potentiation of endoplasmic reticulum Ca(2+) release in brown fat cells. Am J Physiol Cell Physiol 2002; 282:C1016-24. [PMID: 11940517 DOI: 10.1152/ajpcell.00204.2001] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We find that the adrenergic agonist isoproterenol increases intracellular Ca(2+) concentration ([Ca(2+)](i)) in cultured rat brown adipocytes. At the concentration used (10 microM), isoproterenol-induced Ca(2+) responses were sensitive to block by either alpha(1)- or beta-adrenergic antagonists, suggesting an interaction between these receptor subtypes. Despite reliance on beta-adrenoceptor activation, the Ca(2+) response was not due solely to increases in cAMP because, administered alone, the selective beta(3)-adrenergic agonist BRL-37344 or forskolin did not increase [Ca(2+)](i). However, increased cAMP elicited vigorous [Ca(2+)](i) increases in the presence of barely active concentrations of the alpha-adrenergic agonist phenylephrine or the P2Y receptor agonist UTP. Consistent with isoproterenol recruiting only inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca(2+) stores, endoplasmic reticulum store depletion by thapsigargin blocked isoproterenol-induced Ca(2+) increases, but removal of external Ca(2+) did not. These results argue that increases in cAMP sensitize the IP(3)-mediated Ca(2+) release system in brown adipocytes.
Collapse
Affiliation(s)
- Eric V Leaver
- Section of Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616, USA
| | | |
Collapse
|
8
|
den Dekker E, Heemskerk JWM, Gorter G, van der Vuurst H, Donath J, Kroner C, Mikoshiba K, Akkerman JWN. Cyclic AMP raises intracellular Ca(2+) in human megakaryocytes independent of protein kinase A. Arterioscler Thromb Vasc Biol 2002; 22:179-86. [PMID: 11788480 DOI: 10.1161/hq0102.101515] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The immature megakaryoblastic cell line MEG-01 responds to iloprost with an increase in cytosolic Ca(2+) and cAMP. The Ca(2+) response is almost absent in CHRF-288-11 cells, but cAMP formation is preserved in this more mature megakaryoblastic cell line. Also, in human hematopoietic stem cells, iloprost induces a Ca(2+) response and cAMP formation. The Ca(2+) response is downregulated during megakaryocytopoiesis, but cAMP formation remains unchanged. The Ca(2+) increase may be caused by cAMP-mediated inhibition of Ca(2+) sequestration, because it is (1) independent of Ca(2+) entry; (2) mimicked by forskolin, an activator of adenylyl cyclase, and isobutylmethylxanthine, an inhibitor of phosphodiesterases; and (3) preserved in the presence of inhibitors of protein kinase A and inositol-1,4,5-triphosphate receptors. The small GTPase Rap1 has been implicated in the control of Ca(2+) sequestration. Indeed, Rap1 activation parallels the iloprost- and forskolin-induced Ca(2+) increase and is unaffected by the calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N',-tetraacetic acid-AM. These findings reveal a novel mechanism for elevating cytosolic Ca(2+) by cAMP, possibly via GTP-Rap1.
Collapse
Affiliation(s)
- Els den Dekker
- Thrombosis and Haemostasis Laboratory, Department of Haematology, University Medical Center Utrecht, The Netherlands.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Elfervig MK, Graff RD, Lee GM, Kelley SS, Sood A, Banes AJ. ATP induces Ca(2+) signaling in human chondrons cultured in three-dimensional agarose films. Osteoarthritis Cartilage 2001; 9:518-26. [PMID: 11520165 DOI: 10.1053/joca.2000.0435] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE In vivo, chondrocytes are surrounded by an extracellular matrix, preventing direct cell-to-cell contact. Consequently, intercellular communication through gap junctions is unlikely. However, signaling at a distance is possible through extracellular messengers such as nitric oxide (NO) and nucleotides and nucleosides, adenosine triphosphate (ATP), uridine triphosphate (UTP), or adenosine diphosphate (ADP). We hypothesized that chondrons, chondrocytes surrounded by their native pericellular matrix, increase their intracellular calcium concentration ([Ca(2+)]ic) in response to ATP and other signaling molecules and that the source of Ca(2+) is from intracellular stores. The objectives of this study were to determine if chondrons in a 3-D gel respond to ATP by increasing [Ca(2+)]ic through a purinoceptor mechanism and to test whether chondrons in whole tissue samples would respond to ATP in a similar fashion. DESIGN Human chondrons, cultured in a three-dimensional agarose gel or in whole cartilage loaded with Fura-2AM, a calcium sensitive dye, were stimulated with 1, 5 and 10 microM ATP. A ratio-imaging fluorescence technique was used to quantitate the [Ca(2+)]ic. RESULTS ATP-stimulated chondrons increased their [Ca(2+)]ic from a basal level of 60 nM to over 1000 nM. Chondrons incubated in calcium-free medium also increased their [Ca(2+)]ic in response to ATP, indicating the source of Ca(2+) was not extracellular. ATP-induced calcium signaling was inhibited in chondrons pre-treated with suramin, a generic purinoceptor blocker. In addition, UTP and adenosine 5'-O-(3-thiotriphosphate) (ATPgammas) induced a calcium response, but 2-methylthio-ATP (2-MeSATP), ADP, and adenosine did not induce a significant increase in [Ca(2+)]ic, substantiating that the P2Y2 purinoceptor was dominant. Chondrons in whole cartilage increased [Ca(2+)]ic in response to ATP. CONCLUSIONS We conclude that chondrons in 3-D culture respond to ATP by increasing [Ca(2+)]ic via P2Y2 receptor activation. Thus, ATP can pass through the agarose gel and the pericellular matrix, bind purinoceptors and increase intracellular Ca(2+) in a signaling response.
Collapse
Affiliation(s)
- M K Elfervig
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599-7055, USA
| | | | | | | | | | | |
Collapse
|
10
|
Nezu A, Tanimura A, Tojyo Y. Characterization of the ca2 + response mediated by activation of beta-adrenoceptors in rat submandibular ducts. JAPANESE JOURNAL OF PHARMACOLOGY 2000; 84:25-31. [PMID: 11043449 DOI: 10.1254/jjp.84.25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Ca2+ signaling mediated by activation of beta-adrenoceptors was studied in a purified preparation of ducts from rat submandibular glands. At concentrations above 1 nM, isoproterenol (ISO) caused a small but significant increase in cytosolic Ca2+ concentration ([Ca2+]i). The ISO-induced increase in [Ca2+]i was completely inhibited by the beta-adrenoceptor antagonist propranolol but not by the alpha-adrenoceptor antagonist phentolamine. Forskolin was able to mimic the Ca2+ response to ISO. These results suggest that the ISO-induced increase in [Ca2+]i in rat submandibular ducts is mediated by an accumulation of cAMP resulting from activation of beta-adrenoceptors. In the absence of extracellular Ca2+, ISO or forskolin caused a transient increase in [Ca2+]i, indicating Ca2+ mobilization from intracellular Ca2+ stores. Further, stimulation with ISO failed to mobilize Ca2+ after the depletion of intracellular Ca2+ stores by phenylephrine or carbachol, suggesting that the cAMP-mediated increase in [Ca2+]i is due to a Ca2+ release from inositol trisphosphate (IP3)-sensitive Ca2+ stores. As ISO did not stimulate a detectable production of IP3, the cAMP-mediated Ca2+ mobilization may be evoked by a mechanism different from activation of phosphoinositide hydrolysis.
Collapse
Affiliation(s)
- A Nezu
- Department of Dental Pharmacology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | | | | |
Collapse
|
11
|
Tanimura A, Nezu A, Tojyo Y, Matsumoto Y. Isoproterenol potentiates alpha-adrenergic and muscarinic receptor-mediated Ca2+ response in rat parotid cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:C1282-7. [PMID: 10362590 DOI: 10.1152/ajpcell.1999.276.6.c1282] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of the cAMP pathway on the Ca2+ response elicited by phospholipase C-coupled receptor stimulations were studied in rat parotid cells. Although 1 microM isoproterenol (Iso) itself had no effect on the cytosolic Ca2+ concentration, the pretreatment with Iso potentiated Ca2+ responses evoked by phenylephrine. The potentiating effect of Iso was attributed to a shifting of the concentration-response curves of phenylephrine to the left and an increase in the maximal response. Half-maximal potentiation occurred at 3 nM Iso. Iso also potentiated the Ca2+ response elicited by carbachol. The potentiating effect of Iso was mimicked by forskolin (10 microM) and dibutyryl adenosine 3',5'-cyclic monophosphate (2 mM) and was blocked by 10 microM H-89. Iso potentiated the phenylephrine-induced Ca2+ response in the absence of extracellular Ca2+, but Iso did not increase the inositol trisphosphate (IP3) production induced by phenylephrine. These results suggest that the potentiation of the Ca2+ response can be attributed to a sensitization of IP3 receptors by cAMP-dependent protein kinase.
Collapse
Affiliation(s)
- A Tanimura
- Department of Dental Pharmacology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
| | | | | | | |
Collapse
|
12
|
Ryan LM, Kurup IV, Cheung HS. Transduction mechanisms of porcine chondrocyte inorganic pyrophosphate elaboration. ARTHRITIS AND RHEUMATISM 1999; 42:555-60. [PMID: 10088779 DOI: 10.1002/1529-0131(199904)42:3<555::aid-anr21>3.0.co;2-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To investigate cellular signaling mechanisms that influence chondrocyte production of inorganic pyrophosphate (PPi), which promotes calcium pyrophosphate dihydrate (CPPD) crystal deposition. METHODS Articular chondrocyte and cartilage cultures were stimulated with protein kinase C (PKC) activator and adenyl cyclase activator. Generation of extracellular PPi was measured. RESULTS Adenyl cyclase activation resulted in diminished pyrophosphate generation. PKC activation stimulated pyrophosphate elaboration. CONCLUSION Two signaling pathways, cAMP and PKC, modulate generation of extracellular pyrophosphate by cartilage and chondrocytes. They are novel targets for potentially diminishing extracellular pyrophosphate elaboration that leads to CPPD crystal deposition.
Collapse
Affiliation(s)
- L M Ryan
- University of Miami School of Medicine, and Department of Veterans Affairs Medical Center, Florida, USA
| | | | | |
Collapse
|
13
|
Tertyshnikova S, Fein A. Inhibition of inositol 1,4,5-trisphosphate-induced Ca2+ release by cAMP-dependent protein kinase in a living cell. Proc Natl Acad Sci U S A 1998; 95:1613-7. [PMID: 9465064 PMCID: PMC19117 DOI: 10.1073/pnas.95.4.1613] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Interaction of intracellular free calcium ([Ca2+]i) and cAMP signaling mechanisms was examined in intact single megakaryocytes by using a combination of single-cell fluorescence microscopy to measure [Ca2+]i and flash photolysis of caged Ca2+, inositol 1,4, 5-trisphosphate (IP3), or cAMP to elevate rapidly the concentration of these compounds inside the cell. Photolysis of caged IP3 stimulated Ca2+ release from an IP3-sensitive store. The cAMP-elevating agent carbacyclin inhibited this IP3-induced rise in [Ca2+]i but did not affect the rate of Ca2+ removal from the cytoplasm after photolysis of caged Ca2+. Photolysis of caged cAMP during ADP-induced [Ca2+]i oscillations caused the [Ca2+]i oscillation to transiently cease without affecting the rate of Ca2+ uptake and/or extrusion. We conclude that the principal mechanism of cAMP-dependent inhibition of Ca2+ mobilization in megakaryocytes appears to be by inhibition of IP3-induced Ca2+ release and not by stimulation of Ca2+ removal from the cytoplasm. Two inhibitors of cAMP-dependent protein kinase, a specific peptide inhibitor of the catalytic subunit of cAMP protein kinase and KT5720, blocked the inhibitory effect of carbacyclin, indicating that the inhibition of IP3-induced Ca2+-release by carbacyclin is mediated by cAMP-dependent protein kinase.
Collapse
Affiliation(s)
- S Tertyshnikova
- Department of Physiology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3505, USA
| | | |
Collapse
|
14
|
Robin P, Rossignol B, Raymond MN. PKA inhibitor, H-89, affects the intracellular transit of regulated secretory proteins in rat lacrimal glands. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:C262-71. [PMID: 9458736 DOI: 10.1152/ajpcell.1998.274.1.c262] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We tested the effect of H-89, a protein kinase A (PKA) inhibitor, on the intracellular transit of the regulated secretory proteins in rat lacrimal glands. We show that H-89, by itself, induces the secretion of newly synthesized proteins trafficking in its presence but not of proteins already stored in the mature secretory granules. This secretion does not depend on the presence of extracellular Ca2+. The proteins released are identical to those secreted after cholinergic stimulation or under the action of the ionophore A-23187, but the secretion level is approximately 40% lower. The effect of H-89 seems to be due to PKA inhibition because other protein kinase inhibitors (calphostin C, chelerythrine, H-85) do not induce secretion. We further show that H-89 does not modify the rate of glycoprotein galactosylation but induces the secretion of newly galactosylated glycoproteins. Finally, we used a "20 degrees C block" procedure to show that H-89 affects a trans-Golgi network (TGN) or post-TGN step of the secretory pathway. Our results demonstrate that, in lacrimal cells, H-89 affects the intracellular trafficking of secretory proteins, suggesting a role for PKA in this process.
Collapse
Affiliation(s)
- P Robin
- Laboratoire de Biochimie des Transports Cellulaires, Centre National de la Recherche Scientifique, ERS 0571, Université Paris XI, Orsay, France
| | | | | |
Collapse
|