alexa Matrix regulation of skeletal cell apoptosis. Role of calcium and phosphate ions.
Engineering

Engineering

Bioceramics Development and Applications

Author(s): Adams CS, Mansfield K, Perlot RL, Shapiro IM

Abstract Share this page

Abstract Previously, we noted that inorganic phosphate (P(i)), a major component of bone extracellular matrix, induced osteoblast apoptosis (Meleti, Z., Shapiro, I. M., and Adams, C. S. (2000) Bone (NY) 27, 359-366). Since Ca(2+) along with P(i) is released from bone during the resorption process, we advanced the hypothesis that Ca(2+) modulates P(i)-mediated osteoblast apoptosis. To test this hypothesis, osteoblasts were incubated with both ions, and cell death was determined. We noted that a modest increase in the medium Ca(2+) concentrations ([Ca(2+)](e)) of 0.1-1 mm caused a profound and rapid enhancement in P(i)-dependent death of cultured osteoblasts. An elevation in [Ca(2+)](e) alone had no effect on osteoblast viability, whereas Ca(2+) channel blockers failed to inhibit killing of ion pair-treated cells. These results indicated that P(i)-mediated cell death is not dependent on a sustained increase in the cytosolic Ca(2+) concentration. Terminal dUTP nick-end labeling analysis and measurement of caspase-3 activity of the ion pair-treated cells suggested that death was apoptotic. Apoptosis was confirmed using caspase-3 and endonuclease inhibitors. The mitochondrial membrane potential and cytosolic Ca(2+) status of the treated cells were evaluated. After incubation with [Ca(2+) ](e) and P(i), a decrease in mitochondrial fluorescence was noted, suggesting that the ions decreased the mitochondrial transmembrane potential. Subsequent to the fall in mitochondrial membrane potential, there was a transient elevation in the cytosolic Ca(2+) concentration. Results of the study suggest that the ion pair conspire at the level of the plasma membrane to induce intracellular changes that result in loss of mitochondrial function. The subsequent increase in the cytosolic Ca(2+) concentration may trigger downstream events that transduce osteoblast apoptosis. This article was published in J Biol Chem and referenced in Bioceramics Development and Applications

Relevant Expert PPTs

Relevant Speaker PPTs

Recommended Conferences

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

 
© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version
adwords