title: Modulation of hyaluronan catabolism in chondrocytes by mechanical stimuli.
abstract: Hyaluronan (HA) is a component of the extracellular matrices of cartilage contributing to the structural and functional integrity. HA metabolism is regulated by both anabolic and catabolic processes; however, a great deal more of the detail has been unknown yet. The purpose of this study was to clarify the effect of excessive mechanical load on the expression and activity of hyaluronidase (HYAL) in chondrocytes with a special reference to the expressions of IL-1beta and tumor necrosis factor (TNF)-alpha. A cyclic tensile load of 22.8% cell elongation, regarded as an excessive mechanical stimulus, was applied to cultured rabbit knee articular chondrocytes. HYAL1, HYAL2, IL-1beta, and TNF-alpha mRNA levels were examined by quantitative real-time PCR analysis. The HYAL activity in culture medium was examined by HA zymography. Both HYAL1 and HYAL2 mRNA levels were upregulated significantly by the loading in cultured chondrocytes. HYAL activity was also enhanced as compared with unloaded controls. The IL-1beta mRNA level was upregulated significantly by the loading, and TNF-alpha mRNA level was slightly upregulated. HYAL1 and HYAL2 mRNA levels were upregulated significantly by IL-1beta treatment, resulting in a slight increase in HYAL activity. These results show that the expression of HYAL1 and HYAL2 in articular chondrocytes is enhanced by excessive mechanical stimuli and affected in part by induction of IL-1beta, leading to HA catabolism in articular cartilage.
authors: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University, Minami-Ku, Hiroshima 734-8553, Japan. tkotaro@hiroshima-u.ac.jp
authors: Kotaro
authors: K
authors: Tanimoto
authors: Reiko
authors: R
authors: Kitamura
authors: Yuki
authors: Y
authors: Tanne
authors: Takashi
authors: T
authors: Kamiya
authors: Ryo
authors: R
authors: Kunimatsu
authors: Motoko
authors: M
authors: Yoshioka
authors: Nobuaki
authors: N
authors: Tanaka
authors: Eiji
authors: E
authors: Tanaka
authors: Kazuo
authors: K
authors: Tanne
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D019902:Chondrocytes / Q000201:enzymology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006820:Hyaluronic Acid / Q000378:metabolism*; D006821:Hyaluronoglucosaminidase / Q000235:genetics / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013314:Stress, Mechanical; D013718:Tensile Strength; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D018836:Inflammation Mediators; D053583:Interleukin-1beta; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D006820:Hyaluronic Acid; D006821:Hyaluronoglucosaminidase