Autocrine ATP release coupled to extracellular pyrophosphate accumulation in vascular smooth muscle cells

作者：Prosdocimo Domenick A; Douglas Dezmond C; Romani Andrea M; O'Neill W Charles; Dubyak George R^*

来源：American Journal of Physiology - Cell Physiology, 2009, 296(4): C828-C839.

DOI：10.1152/ajpcell.00619.2008

• adenosine 5 '-triphosphate release
• vascular calcification
• ectonucleotide pyrophosphatase
• ectoadenosine 5 '-triphosphatase

Prosdocimo DA, Douglas DC, Romani AM, O'Neill WC, Dubyak GR. Autocrine ATP release coupled to extracellular pyrophosphate accumulation in vascular smooth muscle cells. Am J Physiol Cell Physiol 296: C828-C839, 2009. First published February 4, 2009; doi:10.1152/ajpcell.00619.2008.-Extracellular inorganic pyrophosphate (PP(i)) is a potent suppressor of physiological calcification in bone and pathological calcification in blood vessels. Ectonucleotide pyrophosphatase/phosphodiesterases (eNPPs) generate PP(i) via the hydrolysis of ATP released into extracellular compartments by poorly understood mechanisms. Here we report that cultured vascular smooth muscle cells (VSMC) from rat aorta generate extracellular PP(i) via an autocrine mechanism that involves ATP release tightly coupled to eNPP activity. The nucleotide analog alpha,beta-methylene ATP (MeATP or AMPPCP) was used to selectively suppress ATP metabolism by eNPPs but not the CD39-type ecto-ATPases. In the absence of MeATP, VSMC generated extracellular PP(i) to accumulate >= 600 nM within 2 h while steadily maintaining extracellular ATP at 1 nM. Conversely, the presence of MeATP completely suppressed PP(i) accumulation while increasing ATP accumulation. Probenecid, which inhibits PP(i) efflux dependent on ANK, a putative PP(i) transporter or transport regulator, reduced extracellular PP(i) accumulation by approximately twofold. This indicates that autocrine ATP release coupled to eNPP activity comprises >= 50% of the extracellular PP(i)-generating capacity of VSMC. The accumulation of extracellular PP(i) and ATP was markedly attenuated by reduced temperature but was insensitive to brefeldin A, which suppresses constitutive exocytosis of Golgi-derived secretory vesicles. The magnitude of extracellular PP(i) accumulation in VSMC cultures increased with time postplating, suggesting that ATP release coupled to PPi generation is upregulated as cultured VSMC undergo contact-inhibition of proliferation or deposit extracellular matrix.

• 出版日期2009-4