Endocytosis by cultured mesangial cells and associated changes in prostaglandin E2 synthesis

The mechanism of macromolecule uptake by cultured mesangial cells was studied by use of transmission electron microscopy. In parallel, we investigated the effect of macromolecular uptake on prostaglandin E2 (PGE2) formation. Cultured rat mesangial cells were studied in their third passage. As model molecules, we used colloidal gold particles (10 nm diameter) coated either with polyethylene glycol (PEG) or fresh serum (SCG). Mesangial cells were incubated from 1 to 60 min and up to 12 h with either PEG or SCG particles. Endocytosis of SCG significantly exceeded that of PEG particles. The mechanism involved binding to coated pits, followed by formation of coated vesicles (endosomes), and eventually delivery of particles to lysosomes. Pretreatment with cytochalasin B virtually prevented endocytosis of SCG particles, indicating active participation of the cytoskeleton. Determination of PGE2 production in parallel showed that SCG significantly stimulated PGE2 synthesis within minutes, whereas PEG-coated gold had no effect. When gold particles were coated with decomplemented serum instead of fresh serum, the stimulation of PGE2 was partially, but not completely, prevented, indicating that complement may be one, but not the only ligand responsible for enhanced PGE2 production. Stimulation of PGE2 synthesis by SCG was not dependent on actual endocytosis, as it was not altered by cytochalasin B pretreatment. Thus, surface ligand-receptor interaction may be sufficient to trigger PGE2 synthesis. The interaction between mesangial endocytosis and PGE2 production may be important for glomerular pathophysiology.

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Characterization of ATP receptor responsible for the activation of phospholipase A2 and stimulation of prostaglandin E2 production in thymic epithelial cells

Biochemical Journal ◽

10.1042/bj3080399 ◽

1995 ◽

Vol 308 (2) ◽

pp. 399-404 ◽

Cited By ~ 10

Author(s):

P Liu ◽

M Wen ◽

J Hayashi

Keyword(s):

Epithelial Cells ◽

Prostaglandin E2 ◽

Phospholipase A2 ◽

Enzymic Activity ◽

Pge2 Production ◽

Thymic Epithelial Cells ◽

Cross Linking ◽

Atp Binding ◽

Variant Cell ◽

Stimulation Of

In TEA3A1 rat thymic epithelial cells, ATP stimulates prostaglandin E2 (PGE2) production through activation of phospholipase A2 (PLA2) enzymic activity. The stimulation of PGE2 production tested with other nucleotides indicated the agonist potency of adenosine 5′-[gamma-thio]triphosphate (ATP[S]) > or = UTP > ATP, with ED50 of about 10 microM for ATP[S]. In TEA3A1 cells, cross-linking studies with ATP[35S] revealed the presence of four cell-surface cross-linked bands of 42 kDa, 53 kDa, 83 kDa and 100 kDa in Triton X-100 extracts of TEA3A1 cells by fluorography. Guanosine 5′-[gamma-thio]triphosphate specifically blocked the cross-linking of ATP[35S] to the 53 kDa, 83 kDa and 100 kDa ATP-binding proteins, and inhibited the ATP[S]-mediated stimulation of PGE2 production with an ED50 of about 25 microM. On the other hand, 2-methylthioadenosine triphosphate (2MeSATP) blocked ATP[35S] cross-linking to the 42 kDa protein, but had no effect on ATP[S]-mediated stimulation of PGE2 production. In a variant cell line, TEAvarl, derived from TEA3A1 cells that lost their response to ATP in the activation of PLA2, the presence of 83 kDa ATP-binding protein was not detected. Results from our study suggest that ATP activates PLA2 enzymic activity in TEA3A1 cells by binding to an atypical ATP receptor that has not been described previously.

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Stimulation of prostaglandin E2 (PGE2) production by arachidonic acid, oestrogen and parathyroid hormone in MG-63 and MC3T3-E1 osteoblast-like cells

Prostaglandins Leukotrienes and Essential Fatty Acids ◽

10.1016/j.plefa.2005.08.005 ◽

2005 ◽

Vol 73 (6) ◽

pp. 423-430 ◽

Cited By ~ 12

Author(s):

M. Coetzee ◽

M. Haag ◽

N. Claassen ◽

M.C. Kruger

Keyword(s):

Arachidonic Acid ◽

Parathyroid Hormone ◽

Prostaglandin E2 ◽

Pge2 Production ◽

Stimulation Of

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Effects of vasoactive agents on uptake of immunoglobulin G complexes by mesangial cells

AJP Renal Physiology ◽

10.1152/ajprenal.1990.258.3.f589 ◽

1990 ◽

Vol 258 (3) ◽

pp. F589-F596

Author(s):

P. C. Singhal ◽

A. Santiago ◽

J. Satriano ◽

R. M. Hays ◽

D. Schlondorff

Keyword(s):

Immunoglobulin G ◽

Cytochalasin B ◽

Mesangial Cells ◽

Ang Ii ◽

Hemodynamic Effects ◽

Vasoactive Agents ◽

Camp Content ◽

Gold Particles ◽

Cyclic Monophosphate ◽

Immune Injury

Mesangial handling of immune complexes may be important in immune injury. We examined whether vasoactive agents, independent of hemodynamic effects, could directly influence uptake of immunoglobulin G (IgG) complexes by mesangial cells (MC). Under basal conditions, MC took up more gold particles coated with IgG2b (P less than 0.05) than coated with IgG2a. Preincubation of MC with angiotensin II (ANG II) (5 x 10(-7) M) resulted in enhancement of uptake (P less than 0.05) of IgG2b-gold [7,578 +/- 968 counts per minute (cpm) per well], IgG2a-gold (4,566 +/- 295 cpm/well; P less than 0.01), and bovine serum albumin (BSA)-gold (2,532 +/- 66; P less than 0.05) when compared with respective controls (IgG2b-gold, 5,513 +/- 762 cpm/well; IgG2a-gold, 3,282 +/- 439; BSA-gold, 2,279 +/- 97). Cytochalasin B produced a significant reduction of uptake of IgG2b-gold (2,224 +/- 88 cpm/well) when compared with the uptake by control cells (3,711 +/- 287 cpm/well) (P less than 0.05). Pretreatment of MC with atrial natriuretic peptide (ANP, 10(-9) M) slightly decreased uptake of IgG-gold under basal conditions (P less than 0.05) and decreased the response to ANG II (P less than 0.05). Similarly, dopamine (DA, 10(-6) M) attenuated uptake of IgG2b-gold under basal (P less than 0.01) as well as ANG II-stimulated (P less than 0.01) states. ANP increased mesangial guanosine 3',5'-cyclic monophosphate (cGMP), DA, adenosine 3',5'-cyclic monophosphate (cAMP) content.(ABSTRACT TRUNCATED AT 250 WORDS)

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Synthesis of prostaglandin E2 in different segments of isolated collecting tubules from adult and neonatal rabbits

AJP Renal Physiology ◽

10.1152/ajprenal.1985.248.1.f134 ◽

1985 ◽

Vol 248 (1) ◽

pp. F134-F144 ◽

Cited By ~ 3

Author(s):

D. Schlondorff ◽

J. A. Satriano ◽

G. J. Schwartz

Keyword(s):

Arachidonic Acid ◽

Prostaglandin E2 ◽

Feedback Loop ◽

Pge2 Production ◽

Large Variability ◽

Pge2 Synthesis ◽

Collecting Tubule ◽

Concentrate Urine ◽

Collecting Tubules

Prostaglandin E2 (PGE2) inhibits the action of the antidiuretic hormone (ADH) in isolated collecting tubules. A negative feedback loop has been postulated whereby ADH stimulates PGE2 synthesis. Furthermore, lysyl-bradykinin (LBK) inhibits the antidiuretic effect of ADH, probably via PGE2. Enhanced PGE2 synthesis has also been implicated as contributing to the inability to maximally concentrate urine during the neonatal period. We investigated PGE2 synthesis in microdissected cortical (CCT), medullary (MCT), and branched cortical (BCT) collecting tubules from adult and in corticomedullary collecting tubules (CT) from newborn rabbits. Isolated BCT produced significantly less PGE2 (12 +/- 2 pg X mm-1 X 20 min-1) than CCT (65 +/- 9) or MCT (76 +/- 8) from kidneys of adult rabbits. CT from newborn rabbits produced only 19 +/- 3 pg/mm, significantly less than either CCT or MCT from adults. A large variability in basal PGE2 production and hormonal response was observed from tubule to tubule. Under either basal conditions or in the presence of 2 microM arachidonic acid, LBK enhanced PGE2 synthesis in CCT and MCT from adults. ADH enhanced PGE2 production in MCT under basal conditions and in CCT in the presence of arachidonic acid. Neither LBK nor ADH stimulated PGE2 synthesis in neonatal CT. A23187 consistently stimulated PGE2 synthesis in CCT and MCT from adults and, to a lesser extent, in CT from newborn rabbits. Our results support the hypothesis that ADH and LBK enhance PGE2 synthesis in the collecting tubule. This response is, however, subject to large variations from tubule to tubule and depends on the in vitro incubation conditions.

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Angiotensin II stimulates phospholipases C and A2 in cultured rat mesangial cells

AJP Cell Physiology ◽

10.1152/ajpcell.1987.253.1.c113 ◽

1987 ◽

Vol 253 (1) ◽

pp. C113-C120 ◽

Cited By ~ 89

Author(s):

D. Schlondorff ◽

S. DeCandido ◽

J. A. Satriano

Keyword(s):

Arachidonic Acid ◽

Angiotensin Ii ◽

Phospholipase A2 ◽

Phospholipase C ◽

Mesangial Cells ◽

Inositol Trisphosphate ◽

Pge2 Production ◽

Diacylglycerol Lipase ◽

Stimulation Of ◽

In Cells

Angiotensin II stimulates prostaglandin (PG) E2 formation in mesangial cells cultured from rat renal glomeruli. The interactions between angiotensin II and PGE2 are important in modulating glomerular function. We examined the mechanism for stimulation of PGE2 production in mesangial cells using the putative diacylglycerol-lipase inhibitor RHC 80267 and trifluoperazine (TFP), an agent interfering with Ca2+-CaM-mediated processes. Although RHC 80267 inhibited diacylglycerol-lipase activity in mesangial cells, it did not influence PGE2 production in response to either angiotensin II or A23187. In contrast, TFP (50 microM) inhibited basal PGE2 production and stimulation by angiotensin II and A23187. TFP also decreased 14C release in response to angiotensin from cells prelabeled with [14C]arachidonic acid, which was associated with inhibition of 14C loss from phosphatidylinositol. In cells prelabeled with 32P, orthophosphate angiotensin II caused a rapid hydrolysis of phosphatidylinositol 4,5-bisphospate. TFP enhanced 32P labeling of phosphatidylinositides, but did not prevent the loss of phosphatidylinositol 4,5-bisphosphate in response to angiotensin. This was verified in cells prelabeled with myo-[3H]inositol where angiotensin stimulated formation of [3H]inositol trisphosphate. TFP enhanced formation of [3H]inositol trisphosphate both under basal- and angiotensin II-stimulated conditions. Thus TFP did not inhibit phospholipase C activation by angiotensin. Angiotensin II caused marked increases in [32P]lysophospholipids, indicating activation of also phospholipase A2. This process was inhibited by TFP. Taken together, these results are consistent with stimulation of both phospholipase C and A2 by angiotensin, the latter step responsible for the release of arachidonic acid and PGE2 formation. The activation of phospholipase A2, but not that of phospholipase C, is inhibited by TFP, perhaps by interference with calmodulin-dependent steps.

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Effect of serotonin on prostaglandin synthesis in rat cultured mesangial cells

AJP Renal Physiology ◽

10.1152/ajprenal.1986.251.5.f844 ◽

1986 ◽

Vol 251 (5) ◽

pp. F844-F850 ◽

Cited By ~ 3

Author(s):

T. Knauss ◽

H. E. Abboud

Keyword(s):

Intracellular Calcium ◽

Mesangial Cells ◽

Renal Circulation ◽

Calcium Depletion ◽

Pge2 Synthesis ◽

Significant Stimulation ◽

Adrenergic Antagonists ◽

Glomerular Hemodynamics ◽

Intracellular Calcium Antagonist ◽

Stimulation Of

Serotonin (5-hydroxytryptamine) (5-HT) is a potent vasoactive amine that reduces renal blood flow and glomerular filtration rate. Vasodilator prostaglandins (PGs) modulate the effects of several vasoconstrictors on the renal circulation. Since mesangial cells are smooth muscle-like cells that may regulate glomerular hemodynamics, we studied the effect of 5-HT on PGs synthesis in rat cultured mesangial cells. 5-HT (10(-6)-10(-3) M) resulted in progressive stimulation of prostaglandin E2 (PGE2) synthesis. Significant stimulation in response to 10(-4) M 5-HT started after 2 min of incubation and progressively increased for at least 30 min. This effect was structurally specific for the 5-HT receptor since indole-containing precursors and metabolites of 5-HT as well as the aminergic compounds, adenosine, and dopamine were without effect. Moreover, 5-HT receptor antagonists, but not histaminergic or beta-adrenergic antagonists, abolished 5-HT-stimulated PGE2 synthesis. 5-HT also stimulated prostacyclin (measured as 6-ketoprostaglandin F1 alpha) but not thromboxane synthesis in the same cell cultures. 5-HT-stimulated PGE2 synthesis was not affected by extracellular calcium depletion but was abolished by preincubating the cells with the intracellular calcium antagonist 8-(N,N-diethylamine)-octyl-3,4-5 trimethoxybenzoate (10(-5) M). These studies show that 5-HT stimulates PGE2 and prostacyclin (PGI2) synthesis in mesangial cells via a mechanism dependent on intracellular calcium. These vasodilator PGs may modulate the effect of 5-HT on renal and specifically glomerular hemodynamics.

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Involvement of prostaglandin E2, cAMP, and vasopressin in lithium-induced polyuria

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1988.254.6.r863 ◽

1988 ◽

Vol 254 (6) ◽

pp. R863-R869 ◽

Cited By ~ 14

Author(s):

M. Sugawara ◽

K. Hashimoto ◽

Z. Ota

Keyword(s):

Prostaglandin E2 ◽

Rat Kidney ◽

Urine Volume ◽

Renal Medulla ◽

Pge2 Production ◽

Camp Production ◽

Vasopressin Release ◽

Pge2 Synthesis ◽

Plasma Vasopressin

The involvement of prostaglandin E2 (PGE2), adenosine 3',5'-cyclic monophosphate (cAMP), and vasopressin in lithium-induced polyuria was investigated in rats. Administration of LiCl (4 mmol/kg body wt) for 7 days induced a marked polyuria with a significant excretion of urinary PGE2. Administration of indomethacin (IND, 5 mg/kg body wt) for 4 days to lithium-induced diabetes insipidus (LiDI) rats diminished urine volume by 80% and urinary PGE2 by 85%. The in vitro data of the intact rat kidney showed that lithium stimulated arginine vasopressin (AVP)-induced PGE2 production and suggested that PGE2 suppressed cAMP synthesis in rat renal medulla. The AVP-induced PGE2 synthesis was greater and the AVP-stimulated cAMP production lower in the LiDI rat kidney in vitro. Interference of the vasopressin-associated cAMP system and the increased PGE2 synthesis in the kidney may be involved in the development of LiDI. The reduced cAMP production in the LiDI rat kidney might be partly due to the increased PGE2 synthesis. In LiDI rats plasma vasopressin increased, whereas AVP concentration in the hypothalamus and the neurohypophysis significantly decreased. It is postulated that lithium stimulates vasopressin release from the central nervous system and that elevated plasma vasopressin potentiates PGE2 production in the kidney synergistically with lithium.

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Prostaglandin E2 production in rat IMCD cells. II. Possible role for locally formed dopamine

AJP Renal Physiology ◽

10.1152/ajprenal.1991.261.4.f655 ◽

1991 ◽

Vol 261 (4) ◽

pp. F655-F662 ◽

Cited By ~ 3

Author(s):

T. L. Huo ◽

A. Grenader ◽

P. Blandina ◽

D. P. Healy

Keyword(s):

Prostaglandin E2 ◽

Collecting Duct ◽

Pge2 Production ◽

Acid Decarboxylase ◽

Natriuretic Hormone ◽

Amino Acid Decarboxylase ◽

Maximal Stimulation ◽

Medullary Collecting Duct ◽

Da2 Receptor ◽

Stimulation Of

Dopamine has been proposed as an intrarenal natriuretic hormone. We reported previously that inner medullary collecting duct (IMCD) cells express a novel DA2-like dopamine receptor (namely, DA2K) that is linked to stimulation of prostaglandin E2 (PGE2) production. In this study we examined whether locally formed dopamine could stimulate PGE2 production in cultured IMCD cells. L-Dopa stimulated PGE2 production dose dependently in cultured IMCD cells (concentration for half-maximal stimulation, 54.3 microM; maximal stimulation, 212.7% of basal), with the maximal stimulation similar to that obtained with dopamine. This effect was blocked by aromatic L-amino acid decarboxylase (AADC) inhibitors and DA2-receptor antagonists. IMCD cells also had measurable AADC activity and produced dopamine from exogenously added L-dopa. AADC inhibitors and DA2 antagonists also lowered basal PGE2 levels, suggesting that dopamine was being formed constitutively in culture. These results suggest that cultured IMCD cells have the capacity to take up and convert L-dopa to dopamine, which then stimulates PGE2 production via DA2K receptors. These results further suggest that locally formed dopamine could act as an autocrine/paracrine hormone in the kidney inner medulla to regulate PGE2 synthesis and water and electrolyte excretion.

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Differential stimulation of PGE2 synthesis in mesangial cells by angiotensin and A23187

AJP Cell Physiology ◽

10.1152/ajpcell.1985.248.1.c119 ◽

1985 ◽

Vol 248 (1) ◽

pp. C119-C126 ◽

Cited By ~ 42

Author(s):

D. Schlondorff ◽

J. Perez ◽

J. A. Satriano

Keyword(s):

Arachidonic Acid ◽

Angiotensin Ii ◽

Mesangial Cells ◽

Ionophore A23187 ◽

Arachidonic Acid Release ◽

Tight Coupling ◽

Pge2 Synthesis ◽

Maximal Stimulation ◽

Acid Release ◽

Stimulation Of

The mechanism of arachidonic acid release and prostaglandin E2 (PGE2) synthesis was studied in cultured mesangial cells from rat kidneys. Both the ionophore A23187 and angiotensin II stimulated radioimmunoassayable PGE2 synthesis. The effect of angiotensin occurred within minutes, with half-maximal stimulation around 10(-9) M. In cells prelabeled with [14C]arachidonate, A23187 caused release of [14C]-arachidonate from all phospholipids. In contrast, angiotensin II caused preferential release of [14C]arachidonate from phosphatidylinositol, associated with a significant increase in 14C-labeled phosphatidic acid, mono- and diacylglyceride, and arachidonate. These results indicate that angiotensin preferentially, but not exclusively, stimulates a phosphatidylinositol-specific phospholipase C, whereas A23187 results in unspecific stimulation of phospholipases. The tight coupling between an angiotensin-responsive phospholipid-arachidonate pool and cyclooxygenase may be responsible for the specificity of the response to angiotensin.

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