Apoptosis in microencapsulated juvenile rabbit chondrocytes induced by ofloxacin: role played by beta(1)-integrin receptor.
Quinolone(s) (QNs) is widely used in infection therapy due to its good antimicrobial characteristics. However, QNs-induced arthropathy of immature animals has led to restrictions on the therapeutic use of these antimicrobial agents. The exact mechanism(s) of QNs-induced chondrotoxicity remain unknown. In the present study, we investigated the possible mechanism of ofloxacin (one typical QNs)-induced injuries of chondrocytes. Juvenile rabbit joint chondrocytes cultured in alginate microspheres were incubated with ofloxacin at concentrations of 0, 2, 5, 10, 20, and 40 microg/ml for up to 96 h. Concentration of 10 microg/ml ofloxacin induced apoptosis of chondrocyte with visible apoptotic signs, including degradation of poly(ADP-ribose) polymerase, caspase-3 activation, and DNA ladder formation. Furthermore, extracellular signal-regulated kinase 1/2 (phospho-ERK1/2) and growth factor receptor-bound protein 2 (Grb2) were significantly reduced, and similar changes were also observed in the beta(1)-integrin receptor as assessed by immunoblotting. However, the mRNA level of beta(1)-integrin obtained from reverse transcription-polymerase chain reaction remained unchanged. Results of beta(1)-integrin immunoprecipitation have also shown that beta(1)-integrin did not interact with activated intracellular signaling proteins. In addition, ofloxacin did not induce apoptosis and decrease beta(1)-integrin expression in chondrocytes supplemented with Mg(2+), and the ofloxacin-induced apoptosis was caspase-8-dependent, inhibition of which did not affect the expression mode of phospho-ERK1/2 and beta(1)-integrin. Our results demonstrate that ofloxacin affects beta(1)-integrin receptor functions and the ERK mitogen-activated protein kinase signaling pathway, causing caspase-8-dependent apoptosis after exposure of 48 h.
Sheng
Zhi-Guo
ZG
Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, People's Republic of China.
Peng
Shuangqing
S
Wang
Chang-Yong
CY
Li
Hong-Bo
HB
Hajela
Ravindra K
RK
Wang
Yim-Ei
YE
Li
Qian-Qian
QQ
Liu
Mi-Feng
MF
Dong
Yan-Sheng
YS
Han
Gang
G
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000502:physiology; D053181:Caspase 8 / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D019012:Integrin beta1 / Q000502:physiology*; D020935:MAP Kinase Signaling System; D015242:Ofloxacin / Q000494:pharmacology*; D011817:Rabbits
D019012:Integrin beta1; D015242:Ofloxacin; D048049:Extracellular Signal-Regulated MAP Kinases; D053148:Caspase 3; D053181:Caspase 8