Comparison of Kindlin-2 deficiency-stimulated osteoarthritis-like lesions induced by Prg4CreERT2 versus AggrecanCreERT2 transgene in mice

Qing Yao; Weiyuan Gong; Xiaohao Wu; Donghao Gan; Chu Tao; Sixiong Lin; Minghao Qu; Zhongtian Ouyang; Mingjue Chen; Xinjia Hu; Guozhi Xiao

doi:10.1016/j.jot.2023.05.005

Comparison of Kindlin-2 deficiency-stimulated osteoarthritis-like lesions induced by Prg4^CreERT2 versus Aggrecan^CreERT2 transgene in mice

J Orthop Translat. 2023 May 31:41:12-19. doi: 10.1016/j.jot.2023.05.005. eCollection 2023 Jul.

Authors

Qing Yao¹, Weiyuan Gong^{1

2}, Xiaohao Wu¹, Donghao Gan¹, Chu Tao¹, Sixiong Lin³, Minghao Qu¹, Zhongtian Ouyang¹, Mingjue Chen¹, Xinjia Hu², Guozhi Xiao¹

Affiliations

¹ Department of Biochemistry, School of Medicine, Shenzhen Key Laboratory of Cell Microenvironment, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Southern University of Science and Technology, Shenzhen 518055, China.
² Department of Osteoarthropathy, Shenzhen People's Hospital, The First Affiliated Hospital of Southern University of Science and Technology, Shenzhen 518035, China.
³ Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, Department of Spinal Surgery, The First Afﬁliated Hospital of Sun Yat-sen University, Guangzhou 510080, China.

Abstract

Background: Genetically modified mice are the most useful tools for investigating the gene functions in articular cartilage biology and the pathogenesis of osteoarthritis. The Aggrecan^CreERT2 mice are one of the most reported mouse lines used for this purpose. The Prg4 (proteoglycan 4) gene encodes the lubricin protein and is expressed selectively in chondrocytes located at the superficial layer of the articular cartilage. While the Prg4^GFPCreERT2 knock-in inducible-Cre transgenic mice were generated a while ago, so far, few studies have used this mouse line to perform gene functional studies in cartilage biology.

Methods: We have recently reported that deleting the Fermt2 gene, which encodes the key focal adhesion protein Kindlin-2, in articular chondrocytes by using the Aggrecan^CreERT2 transgenic mice, results in spontaneous osteoarthritis (OA) lesions, which highly mimics the human OA pathologies. In this study, we have compared the Kindlin-2 deficiency-caused OA phenotypes induced by Prg4^GFPCreERT2 with those caused by Aggrecan^CreERT2 using imaging and histological analyses.

Results: We find that Kindlin-2 protein is deleted in about 75% of the superficial articular chondrocytes in the tamoxifen (TAM)-treated Prg4^GFPCreERt2/+; Fermt2^fl/fl mice compared to controls. At 6 months after TAM injections, the OARSI scores of Aggrecan^CreERT2/+; Fermt2^fl/fl and Prg4^GFPCreERt2/+; Fermt2^fl/fl mice were 5 and 3, respectively. The knee joints histological osteophyte and synovitis scores were also significantly decreased in Prg4^GFPCreERT2/+; Fermt2^fl/fl mice compared to those in Aggrecan^CreERT2/+; Fermt2^fl/fl mice. Furthermore, magnitudes of upregulation of the extracellular matrix-degrading enzymes Mmp13 and hypertrophic chondrocyte markers Col10a1 and Runx2 were decreased in Prg4^GFPCreERT2/+; Fermt2^fl/fl versus Aggrecan^CreERT2/+; Fermt2^fl/fl mice. We finally examined the susceptibility of Prg4^GFPCreERT2/+; Fermt2^fl/fl mouse model to surgically induce OA lesions. The pathological features of OA in the TAM-DMM model exhibited significant enhancement in cartilage erosion, proteoglycan loss, osteophyte, and synovitis and an increase in OARSI score in articular cartilage compared with those in corn-oil DMM mice.

Conclusion: Kindlin-2 loss causes milder OA-like lesions in Prg4^{GFPCreERT2/+;}Fermt2^fl/fl than in Aggrecan^CreERT2/+; Fermt2^fl/fl mice. In contrast, Kindlin-2 loss similarly accelerates the destabilization of the medial meniscus-induced OA lesions in both mice.Translational Potential of this Article: Our study demonstrates that Prg4^GFPCreERT2 is a useful tool for gene functional study in OA research. This study provides useful information for investigators to choose appropriate Cre mouse lines for their research in cartilage biology.

Keywords: AggrecanCreERT2; Articular chondrocyte; Kindlin-2; Osteoarthritis; Prg4GFPCreERT2.