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Original Article |
Correspondence to: Matthias Ernst, Ludwig Institute for Cancer Research, PO Royal Melbourne Hospital, VIC 3050, Australia. Tel:61-3-3941-3149 Fax:61-3-9341-3191 E-mail:matthias.ernst{at}ludwig.edu.au.
The receptor subunit gp130 transduces multiple cell typespecific activities of the leukemia inhibitory factor (LIF)/interleukin (IL)-6 family of cytokines through the signal transducer and activator of transcription (STAT) and src homology 2 domainbearing protein tyrosine phosphatase (SHP)-2/ras/Erk pathways. To define STAT-dependent physiological responses, we generated mice with a COOH-terminal gp130
STAT "knock-in" mutation which deleted all STAT-binding sites. gp130
STAT mice phenocopyed mice deficient for IL-6 (impaired humoral and mucosal immune and hepatic acute phase responses) and LIF (failure of blastocyst implantation). However, unlike mice with null mutations in any of the components in the gp130 signaling pathway, gp130
STAT mice also displayed gastrointestinal ulceration and a severe joint disease with features of chronic synovitis, cartilaginous metaplasia, and degradation of the articular cartilage. Mitogenic hyperresponsiveness of synovial cells to the LIF/IL-6 family of cyto-kines was caused by sustained gp130-mediated SHP-2/ras/Erk activation due to impaired STAT-mediated induction of suppressor of cytokine signaling (SOCS) proteins which normally limits gp130 signaling. Therefore, the joint pathology in gp130
STAT mice is likely to arise from the disturbance of the otherwise balanced activation of the SHP-2/ras/Erk and STAT signaling cascades emanating from gp130.
Key Words: infertility, signal transduction, STAT, interleukin, gene targeting
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