Ceramide-induced cell death/survival in murine osteoblasts

Area of Science:

• Cell Biology
• Biochemistry
• Bone Biology

Background:

• Programmed cell death (PCD), or apoptosis, is a critical cellular process.
• Osteoblasts are key cells in bone remodeling.
• The role of ceramide in osteoblast PCD and survival is not fully understood.

Purpose of the Study:

• To investigate the effect of ceramide on primary osteoblast viability and PCD.
• To identify the intracellular signaling pathways involved in ceramide-mediated effects on osteoblasts.

Main Methods:

• Cell viability was assessed using the MTT assay.
• Osteoblast apoptosis was determined by nuclear morphology and DNA fragmentation.
• Specific inhibitors of protein kinase C (PKC), protein phosphatase 1 (PP1), and phosphatidylinositol-3 kinase (PI3K) were used to probe signaling pathways.

Main Results:

• Low ceramide concentrations (or=2 x 10(-6) M) reduced it.
• Increased intracellular ceramide levels induced osteoblast apoptosis.
• Ceramide-induced survival involved PKC zeta and PP1, while apoptosis involved PP1 and PKC delta.

Conclusions:

• Ceramide differentially regulates osteoblast survival and apoptosis via distinct signaling pathways.
• Modulation of intracellular ceramide levels may play a significant role in bone remodeling processes.