Expression of the murine plasma cell nucleotide pyrophosphohydrolase PC-1 is shared by human liver, bone, and cartilage cells. Regulation of PC-1 expression in osteosarcoma cells by transforming growth factor-beta.

Abstract

The identification of PC-1 as an NTPPPH expressed in cells derived from bone and cartilage may prove useful in furthering the understanding of the role of NTPPPH in physiologic and pathologic mineralization. (J. Clin. Invest. 1994. 94:560-567.)

Differential effects of aging on human chondrocyte responses to transforming growth factor β. Increased pyrophosphate production and decreased cell proliferation

“…PC-1 expression. The TGFP effect on PPi production was partially related to an increase in NTPPPH activity, and, in human chondrocytes, PC-1 appears to be the molecule expressing most of the NTPPPH activity (28). Comparison of chondrocytes from old and young donors did not show a difference in basal or TGFPinduced PC-1 expression (data not shown).…”

“…The 5'-nucleotide phosphodiesterase I assay was performed for measurement of NTPPPH activity, using as substrate 1 mM p-nitrophenyl thymidine 5'-monophosphate (Sigma) in 50 mM HEPES-buffered DMEM containing 1.6 mM MgCl,, pH 8.0, in a volume of 0.5 ml, to which 0.05 ml of sample was added for 1 hour (28). The assay was halted by addition of 4 volumes of 100 mM NaOH, and absorbance at optical density 410 nm was determined.…”

“…TGFP treatment of porcine chondrocytes was shown to up-regulate membrane and extracellular NTPPPH activity by up t o 36% (24). Plasma cell membrane glycoprotein-1 (PC-1) was identified as a species of human chondrocyte NTPPPH (28). Furthermore, de novo transcription of PC-1 in a variety of cells induced intracellular PPi generation proportional to the increment in NTPPPH activity (29).…”

Extracellular nucleotide metabolism and signaling in the pathophysiology of articular cartilage

“…Western blot analysis of OA articular chondrocytes revealed a major 115-130-kd protein band and a minor 60-kd signal for NPP1 (53), suggesting the presence of a soluble form. Soluble NPP1 was detected in human knee synovial fluids (53,54) and in conditioned media from cultured articular chondrocytes (53).…”

Monogenic Phosphate Balance Disorders

“…In mice, ENPP1 is expressed in plasma cells, on hepatocytes, renal tubules, salivary duct epithelium, epididymis, capillary endothelium in the brain, and chondrocytes (Harahap and Goding 1988). In man it has been shown that ENPP1 is expressed in liver, cartilage and bone, and is thought to regulate physiological mineralization processes and pathological chondrocalcinosis (Huang, Rosenbach et al 1994). Homozygous mutations in ENPP1 are known to cause generalized arterial calcifications of infancy (GACI) (Rutsch, Vaingankar et al 2001;Rutsch, Ruf et al 2003).…”