Parathyroid hormone stimulates phosphoinositide metabolism and intracellular calcium mobilization in osteoblast-like clone MC3T3-E1 cells

Abstract

ABSTRUCTThe effects of parathyroid hormone (rat 1-34 fragment, rPTH) on phosphoinositide metabolism and intracellular Ca 2+ mobilization were studied in a osteoblast-like clone MC3T3-E1 cells, rPTH caused a transient rise in intracellular Ca 2+ in a dose-dependent manner. Significant Ca 2 + increase was still observed under the extracellular Ca 2 +-free condition. In addition, 100nM rPTH stimulated rapid formation of both 1,2-diacylglycerol (1,2-DAG) and inositol 1,4,5-trisphosphate (Ins (1,4,5) P3), indicating agonist-triggered hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2).The current observations suggested that the rPTH-induced increase of intracellular Ca 2 + was in part due to internal Ca 2 + release mediated by Ins (1,4,5)P3. These resultsindicate possible involvement of phosphoiniositide metabolism in signal transduction of PTH-stimulated osteoblastic ceUs.

Potentiation by cholera toxin of bradykinin-induced inositol phosphate production in the osteoblast-like cell line MC3T3-E1

“…To this end, MC3T3-E1 cells were incubated with dibutyryl cyclic AMP (1 mM, 30 min) or with forskolin (100 ,uM, 45 min) plus 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor (150 1tM). We have previously observed that pretreatment with forskolin for 30 min augmented the cyclic AMP level by 40-fold in MC3T3-E1 cells [31]. As shown in Table 2 (Expt.…”

“…The cells were maintained in a-minimal essential medium (a.-MEM) containing 10 % fetal calf serum, penicillin (100 units/ml) and streptomycin (100 units/ml) at 37°C in air/CO2 (19:1). Cells were subcultured every 3 days as previously described [30,31].…”