Open AccessTranscription Factor Mohawk and the Pathogenesis of Human Anterior Cruciate Ligament Degradation
Author(s) -
Nakahara Hiroyuki,
Hasegawa Akihiko,
Otabe Koji,
Ayabe Fumiaki,
Matsukawa Tetsuya,
Onizuka Naoko,
Ito Yoshiaki,
Ozaki Toshifumi,
Lotz Martin K.,
Asahara Hiroshi
Publication year - 2013
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/art.38020
Subject(s) - mohawk , anterior cruciate ligament , pathogenesis , transcription factor , medicine , risk factor , cancer research , biology , anatomy , genetics , gene , computer science , library science
Objective To investigate the expression and function of Mohawk (MKX) in human adult anterior cruciate ligament (ACL) tissue and ligament cells from normal and osteoarthritis (OA)–affected knees. Methods Knee joints were obtained at autopsy (within 24–48 hours postmortem) from 13 donors with normal knees (mean ± SD age 36.9 ± 11.0 years), 16 donors with knee OA (age 79.7 ± 11.4 years), and 8 aging donors without knee OA (age 76.9 ± 12.9 years). All cartilage surfaces were graded macroscopically. MKX expression was analyzed by immunohistochemistry and quantitative polymerase chain reaction. ACL‐derived cells were used to study regulation of MKX expression by interleukin‐1β (IL‐1β). MKX was knocked down with small interfering RNA (siRNA) to analyze the function of MKX in extracellular matrix (ECM) production and differentiation in ACL‐derived cells. Results The expression of MKX was significantly decreased in ACL‐derived cells from OA knees compared with normal knees. Consistent with this finding, immunohistochemistry analysis showed that MKX‐positive cells were significantly reduced in ACL tissue from OA donors, in particular in cells located in disorientated fibers. In ACL‐derived cells, IL‐1β strongly suppressed MKX expression and reduced expression of the ligament ECM genes COL1A1 and TNXB . In contrast, SOX9 , a chondrocyte master transcription factor, was up‐regulated by IL‐1β treatment. Importantly, knockdown of MKX expression with siRNA up‐regulated SOX9 expression in ACL‐derived cells, whereas the expression of COL1A1 and TNXB was reduced. Conclusion Reduced expression of MKX is a feature of degenerated ACL in OA‐affected joints, and this may be mediated in part by IL‐1β. MKX appears necessary to maintain the tissue‐specific cellular differentiation status and ECM production in adult human tendons and ligaments.