Caspase-9 is traditionally considered the initiator caspase of the intrinsic apoptotic pathway. In the past decade, however, other functions beyond initiation/execution of cell death have been described including cell type-dependent regulation of proliferation, differentiation/maturation, mitochondrial, and endosomal/lysosomal homeostasis. As previous studies revealed nonapoptotic functions of caspases in osteogenesis and bone homeostasis, this study was performed to identify proteins and pathways deregulated by knockout of caspase-9 in mouse MC3T3-E1 osteoblasts. Data-independent acquisition-parallel accumulation serial fragmentation (diaPASEF) proteomics was used to compare protein profiles of control and caspase-9 knockout cells. A total of 7669 protein groups were quantified, and 283 upregulated/141 downregulated protein groups were associated with the caspase-9 knockout phenotype. The deregulated proteins were mainly enriched for those associated with cell migration and motility and DNA replication/repair. Altered migration was confirmed in MC3T3-E1 cells with the genetic and pharmacological inhibition of caspase-9. ABHD2, an established regulator of cell migration, was identified as a possible substrate of caspase-9. We conclude that caspase-9 acts as a modulator of osteoblastic MC3T3-E1 cell migration and, therefore, may be involved in bone remodeling and fracture repair.

• Keywords
• ABHD2, Caspase 9, diaPASEF, migration, osteoblasts, proteomics,
• MeSH
• Cell Line MeSH
• Gene Knockout Techniques MeSH
• Caspase 9 * metabolism   genetics   MeSH
• Mice MeSH
• Osteoblasts * metabolism   cytology   MeSH
• Cell Movement * MeSH
• Proteomics * methods   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Casp9 protein, mouse MeSH Browser
• Caspase 9 * MeSH