SPI1 activates mitochondrial unfolded response signaling to inhibit chondrocyte senescence and relieves...

Area of Science:

• Cell Biology
• Biochemistry
• Pathology

Background:

• Chondrocyte senescence is a key feature of osteoarthritis (OA).
• Mechanical stress contributes to chondrocyte aging, but the exact mechanisms are unclear.

Purpose of the Study:

• To investigate the role of SPI1 in chondrocyte senescence and OA pathogenesis.
• To elucidate the signaling pathway by which SPI1 influences chondrocyte aging.

Main Methods:

• Investigated SPI1's effect on chondrocyte senescence and OA progression in vitro and in vivo.
• Analyzed SPI1's binding to the PERK promoter and its impact on PERK activity.
• Examined the role of PERK-mediated eIF2α phosphorylation and mitochondrial unfolded protein response (UPR^mt) activation.
• Utilized mouse models of mechanical overload-induced OA and adenovirus-mediated gene delivery.

Main Results:

• SPI1 counteracts chondrocyte senescence and inhibits OA progression.
• SPI1 promotes PERK transcriptional activity, leading to eIF2α phosphorylation and UPR^mt activation.
• SPI1 deficiency exacerbates OA progression by impairing UPR^mt activation.
• Overexpression of SPI1 and PERK via adenovirus vectors reduced cartilage degeneration.

Conclusions:

• SPI1 plays a critical role in preventing chondrocyte senescence and OA progression by activating UPR^mt signaling through PERK.
• The SPI1-PERK-UPR^mt axis represents a novel therapeutic target for osteoarthritis.