Abstract
Abnormal growth of glomerular mesangial cells (GMCs) contributes to the pathophysiology of many types of nephropathy. Because adenosine is an autocrine/paracrine factor that potentially could regulate GMC proliferation and because the extracellular 3′,5′-cAMP-adenosine pathway (i.e., the conversion of extracellular 3′,5′-cAMP to 5′-AMP and adenosine on the cell surface) could generate adenosine in the biophase of GMC receptors, we investigated the role of the 3′,5′-cAMP-adenosine pathway in modulating growth [cell proliferation, DNA synthesis ([3H]thymidine incorporation), collagen synthesis ([3H]proline incorporation), and mitogen-activated protein kinase activity] of GMCs. The addition of exogenous 3′,5′-cAMP to human GMCs increased extracellular levels of 5′-AMP, adenosine, and inosine, and 3-isobutyl-1-methylxanthine (phosphodiesterase inhibitor), 1,3-dipropyl-8-p-sulfophenylxanthine (ecto-phosphodiesterase inhibitor), and α,β-methylene-adenosine-5′-diphosphate (ecto-5′-nucleotidase inhibitor) attenuated the increases in adenosine and inosine. Forskolin augmented extracellular 3′,5′-cAMP and adenosine concentrations, and 2′,5′-dideoxyadenosine (adenylyl cyclase inhibitor) blocked these increases. Exogenous 3′,5′-cAMP and forskolin inhibited all indices of cell growth, and antagonism of A2 [(E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methylxanthine, KF17837] or A1/A2 (1,3-dipropyl-8-p-sulfophenylxanthine, DPSPX), but not A1 (8-cyclopentyl-1,3-dipropylxanthine), or A3{N-(2-methoxyphenyl)-N′-[2-(3-pyridinyl)-4-quinazolinyl]-urea, VUF5574}, adenosine receptors blocked the growth-inhibitory actions of exogenous 3′,5′-cAMP, but not the effects of 8-bromo-3′,5′-cAMP (stable 3′,5′-cAMP analog). Erythro-9-(2-hydroxy-3-nonyl)adenine (adenosine deaminase inhibitor) plus 5-iodotubercidin (adenosine kinase inhibitor) enhanced the growth inhibition by exogenous 3′,5′-cAMP and forskolin, and A2 receptor antagonism blocked this effect. In rat GMCs, down-regulation of A2B receptors with antisense, but not sense or scrambled, oligonucleotides abrogated the inhibitory effects of 3′,5′-cAMP and forskolin on cell growth. The extracellular 3′,5′-cAMP-adenosine pathway exists in GMCs and attenuates cell growth via A2B receptors. Pharmacological augmentation of this pathway could abate pathological glomerular remodeling.
Footnotes
The work was supported by the Swiss National Science Foundation [Grants 3200B0-106098/1, 320000-117998/1]; Oncosuisse [Grant OCS-01551-08-2004], EMDO Stiftung; and the National Institutes of Health [Grants HL069846, DK068575, DK079307].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.166371.
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ABBREVIATIONS:
- GMC
- glomerular mesangial cell
- PDE
- phosphodiesterase
- 5′-NT
- 5′-nucleotidase
- MAPK
- mitogen-activated protein kinase
- AMPCP
- α,β-methylene-adenosine-5′-diphosphate
- Br-cAMP
- 8-bromo-3′,5′-cyclic monophosphate
- DDA
- 2′,5′-dideoxyadenosine
- DPSPX
- 1,3-dipropyl-8-p-sulfophenylxanthine
- DPCPX
- 8-cyclopentyl-1,3-dipropylxanthine
- EHNA
- erythro-9-(2-hydroxy-3-nonyl)adenine
- IBMX
- 3-isobutyl-1-methylxanthine
- VUF5574
- N-(2-methoxyphenyl)-N′-[2-(3-pyridinyl)-4-quinazolinyl]-urea
- FOR
- forskolin
- KF17837
- (E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methylxanthine
- ITUB
- 5-iodotubercidin
- PD98059
- 2′-amino-3′-methoxyflavone
- FCS
- fetal calf serum
- PDGF-BB
- platelet-derived growth factor-BB
- PBS
- phosphate-buffered saline
- HPLC
- high-performance liquid chromatography.
- Received January 25, 2010.
- Accepted February 23, 2010.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
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