Abstract
Objective
Enhanced glycolysis is a metabolic hallmark of chondrocytes in osteoarthritis (OA); however, the roles of the glycolytic rate-limiting enzyme hexokinase 2 (HK2) in cartilage remain poorly understood.
Methods
Mice and cell models involving HK2 knockout in Col2a1-expressing chondrocytes and 3-bromopyruvate (3-BrPA) treatment are utilized to assess the potential impact of HK2 blockage on cartilage
ex vivo
and
in vivo
. Additionally, we analyzed published single-cell RNA sequencing (scRNA-seq) datasets from human articular cartilage and integrated these with bulk RNA-seq data from HK2-deficient chondrocytes to characterize HK2 expression features across conditions. The
in vivo
effects of HK2 inhibition on OA progression were evaluated using a destabilization of the medial meniscus (DMM)-induced model, through both chondrocyte HK2 deletion and 3-BrPA administration.
Results
Both pharmacological inhibition and genetic deletion of HK2 impair chondrocyte differentiation
ex vivo
and suggest a promoted calcification-like process. Through pseudotime analysis of published single-cell RNA sequencing (scRNA-seq) datasets from human articular cartilages, we further identified that HK2 is differentially expressed across conditions, with a feature of a relatively high expression level at terminal stages of chondrocyte differentiation in the context of OA. We next confirmed HK2 deficiency in chondrocytes significantly exacerbated OA progression but having no impact on skeletal development in mice.
Conclusions
Our findings reveal a novel, critical role for HK2 in regulating chondrocyte differentiation both
ex vivo
and
in vivo
, likely by preserving cartilage function under stress. Consequently, targeting HK2 as a therapeutic strategy for OA requires careful consideration of potential risks.