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HSC70 mediated autophagic degradation of oxidized PRL2 is responsible for osteoclastogenesis and inflammatory bone destruction


Inflammation leads to systemic osteoporosis or local bone destruction, however, the underlying molecular mechanisms are still poorly understood. In this study, we report that PRL2 is a negative regulator of osteoclastogenesis and bone absorption. Mice with PRL2 deficiency exhibit a decrease in bone volume and an increase in osteoclast numbers. PRL2 negatively regulates RANKL-induced reactive oxygen species production through the activation of RAC1, thus PRL2 deficient osteoclast precursors have both increased osteoclast differentiation ability and bone resorptive capacity. During inflammation, oxidized PRL2 is a selected substrate of HSC70 and conditions of oxidative stress trigger rapid degradation of PRL2 by HSC70 mediated endosomal microautophagy and chaperone-mediated autophagy. Ablation of PRL2 in mouse models of inflammatory bone disease leads to an increase in the number of osteoclasts and exacerbation of bone damage. Moreover, reduced PRL2 protein levels in peripheral myeloid cells are highly correlated with bone destruction in a mouse arthritis model and in human rheumatoid arthritis, while the autophagy inhibitor hydroxychloroquine blocked inflammation-induced PRL2 degradation and bone destruction in vivo. Therefore, our findings identify PRL2 as a new regulator in osteoimmunity, providing a link between inflammation and osteoporosis. As such, PRL2 is a potential therapeutic target for inflammatory bone disease and inhibition of HSC70 mediated autophagic degradation of PRL2 may offer new therapeutic tools for the treatment of inflammatory bone disease.

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Fig. 1: PRL2 deficiency decreases bone mass and enhances the number of osteoclasts in vivo.
Fig. 2: PRL2 deficient monocytes and macrophages have increased osteoclastogenic capacity in vitro.
Fig. 3: PRL2 deficiency enhances the canonical RANK-signaling pathway via Rac1 and ROS.
Fig. 4: PRL2 bearing KFERQ-like motif is recognized by HSC70 and degraded via lysosomal pathway under oxidative stress.
Fig. 5: PRL2 negatively regulates inflammatory bone diseases.
Fig. 6: HCQ blocks PRL2 degradation and ameliorates bone loss.

Data availability

All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.


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We are grateful to Dr. Qing Zhong for providing reagents including Torin1 (Selleck Chemicals, USA), and rabbit anti-LC3B antibody. We thank Dr. Qian Zhao for providing the pLVX-KFERQ-PA-mCherryN1 plasmid. We would like to thank Dr. Fubin Li for providing K/B mice. We would like to thank Dr. Huabing Li for providing RAW 264.7 cells expressing Cas9. Last, we would like to thank Dr. Helena Helmby for editing the manuscript.


This work was supported by the National Natural Science Foundation of China (81971486), the Natural Science Foundation of Shanghai (19ZR1428500), and Innovative research team of high-level local universities in Shanghai, the Fifth Round of Three-Year Public Health Action Plan of Shanghai (No. GWV-10.1-XK13).

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Authors and Affiliations



ZW generated the initial ideas and proposed the hypotheses. ZW, QL, XD, ZT, and JL designed the study. ZW and GC supervised the study. QL and XD conducted the key experiments. BR, SK, CL, JC, CW, and XN performed experiments. TY, WW, and WX provided the human samples. KL and BL provided reagents. XD provided the animals. ZW, QL, and ZT performed the data analysis, interpretation of the results and wrote the manuscript.

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Correspondence to Guangjie Chen or Zhaojun Wang.

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The authors declare no competing interests.

Ethic approval

Human subject research was approved by the Ethics Committee of Guanghua Hospital Affiliated to Shanghai University of Traditional Chinese Medicine (Project number 2021-K-46), and all subjects provided signed informed consent. This study has been registered at (ChiCTR2100046850). All animal experiments were approved by the Institutional Animal Care and Use Committee (IACUC) of Shanghai Jiao Tong University School of Medicine (Project number A-2019-053, A-2019-069).

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Li, Q., Yue, T., Du, X. et al. HSC70 mediated autophagic degradation of oxidized PRL2 is responsible for osteoclastogenesis and inflammatory bone destruction. Cell Death Differ (2022).

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