Involvement of ADAM12 in Chondrocyte Differentiation by Regulation of TGF-β1–Induced IGF-1 and RUNX-2 Expressions

Abstract

A disintegrin and metalloproteinase 12 (ADAM12) is known to be involved in chondrocyte proliferation and maturation however the mechanisms are not fully understood. In this study expression and localization of ADAM12 during chondrocyte differentiation was examined in the mouse growth plate by immunohistochemistry. Adam12 expression during ATDC5 chondrogenic differentiation was examined by real-time PCR and compared with the expression pattern of type X collagen. The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 system was used to generate Adam12-knockout (KO) ATDC5 cells. Adam12-KO and Adam12 overexpressing cells were used for analyses of ADAM12 expression with or without TGF-β1 stimulation. ADAM12 was identified predominantly in chondrocytes of the proliferative zone in mouse growth plates by immunohistochemistry. Adam12 was upregulated prior to Col10a1 during chondrogenic differentiation in wildtype ATDC5 cells. In Adam12-KO ATDC5 cells, following initiation of chondrogenic differentiation, we observed a reduction in Igf-1 expression along with an upregulation of hypertrophy associated Runx2, Col10a1, and type X collagen protein expression. In ATDC5 wild-type cells, stimulation with TGF-β1 upregulated the expression of Adam12 and Igf-1 and downregulated the expression of Runx2. In contrast, in Adam12-KO ATDC5 cells, these TGF-β1-induced changes were suppressed. Adam12 overexpression resulted in an upregulation of Igf-1 and downregulation of Runx2 expression in ATDC5 cells. The findings suggest that ADAM12 is important in the 2 regulation of chondrocyte differentiation, potentially by regulation of TGF-β1 dependent signaling and that targeting of ADAM12 may have a role in management of abnormal chondrocyte differentiation.

Age and diet shape the genetic architecture of body weight in Diversity Outbred mice

“…Edem3, another candidate gene at the locus on chromosome 1 linked to body weight in early development (Supplemental Figure S5A), has previously been linked to short stature in humans based on family-based exome sequencing and differential expression in chondrocytes [44,]. Possibly sharing a similar mechanism, Adam12, a candidate gene in both a diet-independent and diet-dependent locus on chromosome 7, is known to play an important role in the differentiation, proliferation, and maturation of chondrocytes [45,].…”

miR-29b inhibits TGF-β1-induced cell proliferation in articular chondrocytes

“…Previous studies have reported that the downregulation of ADAM12 could inhibit TGF-β1-induced cell proliferation in various cells types including human OA chondrocytes, murine stomal cells, and mouse pituitary adenoma cells [ 19 , 30 , 31 ]. In addition, a recent study indicated that ADAM12 overexpression can stimulate IGF-1 expression which is a major mitogen [ 32 ]. These data suggest that ADAM12 may mediate the pro-proliferation actions of TGF-β1.…”

Genetic Variants and Protein Alterations of Selenium- and T-2 Toxin-Responsive Genes Are Associated With Chondrocytic Damage in Endemic Osteoarthropathy

“…ADAM12 was upregulated prior to Col10a1 during chondrogenic differentiation in ATDC5 cells. In addition, TGF-β1–induced ADAM12 overexpression resulted in upregulation of Igf-1 and downregulation of Runx2 expression ( Horita et al, 2019 ). The protein RUNX2 is a crucial transcription factor for type X collagen expression and chondrocyte hypertrophy and is known to regulate endochondral ossification through the control of chondrocyte proliferation and differentiation ( Chen et al, 2014 ).…”