Caspase-8 Deficient Osteoblastic Cells Display Alterations in Non-Apoptotic Pathways

Area of Science:

• Cell Biology
• Bone Biology
• Molecular Biology

Background:

• Caspase-8 is crucial for the extrinsic apoptotic pathway.
• Active caspase-8 is present in osteoblasts, even non-apoptotic ones.
• In vivo studies on caspase-8 in bone are limited due to embryonic lethality of knock-outs.

Purpose of the Study:

• To investigate the non-apoptotic roles of caspase-8 in osteoblasts.
• To determine the effects of caspase-8 deficiency on osteogenic gene expression, proliferation, and autophagy in MC3T3-E1 cells.

Main Methods:

• CRISPR/Cas9 technology was used to eliminate caspase-8 in MC3T3-E1 osteoblast cells.
• Osteogenic gene expression was analyzed using PCR Array.
• Proliferation, caspase cascades, and autophagy response were evaluated.

Main Results:

• Caspase-8 deficient osteoblasts showed inhibited osteogenic differentiation, reduced mineralization, and lower alkaline phosphatase activity.
• Key affected osteogenic genes included downregulated Ctsk and upregulated Gdf10, alongside other genes involved in bone formation.
• Autophagosome formation was unaffected, but expression of certain autophagy-related genes was downregulated.

Conclusions:

• Caspase-8 plays a significant role in non-apoptotic osteogenic pathways.
• Caspase-8 deficiency negatively impacts osteoblast function and bone formation.
• These findings offer new insights into the multifaceted functions of caspase-8 in bone biology.