TY - JOUR
T1 - EGFR signaling is critical for maintaining the superficial layer of articular cartilage and preventing osteoarthritis initiation
AU - Jia, Haoruo
AU - Ma, Xiaoyuan
AU - Tong, Wei
AU - Doyran, Basak
AU - Sun, Zeyang
AU - Wang, Luqiang
AU - Zhang, Xianrong
AU - Zhou, Yilu
AU - Badar, Farid
AU - Chandra, Abhishek
AU - Lucas Lu, X.
AU - Xia, Yang
AU - Han, Lin
AU - Enomoto-Iwamoto, Motomi
AU - Qina, Ling
PY - 2016/12/13
Y1 - 2016/12/13
N2 - Osteoarthritis (OA) is the most common joint disease, characterized by progressive destruction of the articular cartilage. The surface of joint cartilage is the first defensive and affected site of OA, but our knowledge of genesis and homeostasis of this superficial zone is scarce. EGFR signaling is important for tissue homeostasis. Immunostaining revealed that its activity is mostly dominant in the superficial layer of healthy cartilage but greatly diminished when OA initiates. To evaluate the role of EGFR signaling in the articular cartilage, we studied a cartilage-specific Egfr-deficient (CKO) mouse model (Col2-Cre EgfrWa5/flox). These mice developed early cartilage degeneration at 6 mo of age. By 2 mo of age, although their gross cartilage morphology appears normal, CKO mice had a drastically reduced number of superficial chondrocytes and decreased lubricant secretion at the surface. Using superficial chondrocyte and cartilage explant cultures, we demonstrated that EGFR signaling is critical for maintaining the number and properties of superficial chondrocytes, promoting chondrogenic proteoglycan 4 (Prg4) expression, and stimulating the lubrication function of the cartilage surface. In addition, EGFR deficiency greatly disorganized collagen fibrils in articular cartilage and strikingly reduced cartilage surface modulus. After surgical induction of OA at 3 mo of age, CKO mice quickly developed the most severe OA phenotype, including a complete loss of cartilage, extremely high surface modulus, subchondral bone plate thickening, and elevated joint pain. Taken together, our studies establish EGFR signaling as an important regulator of the superficial layer during articular cartilage development and OA initiation.
AB - Osteoarthritis (OA) is the most common joint disease, characterized by progressive destruction of the articular cartilage. The surface of joint cartilage is the first defensive and affected site of OA, but our knowledge of genesis and homeostasis of this superficial zone is scarce. EGFR signaling is important for tissue homeostasis. Immunostaining revealed that its activity is mostly dominant in the superficial layer of healthy cartilage but greatly diminished when OA initiates. To evaluate the role of EGFR signaling in the articular cartilage, we studied a cartilage-specific Egfr-deficient (CKO) mouse model (Col2-Cre EgfrWa5/flox). These mice developed early cartilage degeneration at 6 mo of age. By 2 mo of age, although their gross cartilage morphology appears normal, CKO mice had a drastically reduced number of superficial chondrocytes and decreased lubricant secretion at the surface. Using superficial chondrocyte and cartilage explant cultures, we demonstrated that EGFR signaling is critical for maintaining the number and properties of superficial chondrocytes, promoting chondrogenic proteoglycan 4 (Prg4) expression, and stimulating the lubrication function of the cartilage surface. In addition, EGFR deficiency greatly disorganized collagen fibrils in articular cartilage and strikingly reduced cartilage surface modulus. After surgical induction of OA at 3 mo of age, CKO mice quickly developed the most severe OA phenotype, including a complete loss of cartilage, extremely high surface modulus, subchondral bone plate thickening, and elevated joint pain. Taken together, our studies establish EGFR signaling as an important regulator of the superficial layer during articular cartilage development and OA initiation.
KW - Articular cartilage
KW - Chondrocyte
KW - EGFR
KW - Lubrication
KW - Osteoarthritis
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U2 - 10.1073/pnas.1608938113
DO - 10.1073/pnas.1608938113
M3 - Article
C2 - 27911782
AN - SCOPUS:85006098488
SN - 0027-8424
VL - 113
SP - 14360
EP - 14365
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 50
ER -