Annex Publishers | www.annexpublishers.com Research Article Open Access Volume 1 | Issue 1 Volume 1 | Issue 1 Journal of Cell Biology and Histology Introduction he Efect of Interleukin-6-Type Cytokines and Adiponectin on MAPK Activation in the Immortalized Human Chondrocyte C28/I2 Line and Normal Human Chondrocytes Wylie MA 1 , Meszaros EC 1 and Malemud CJ *1,2 1 Arthritis Research Laboratory, Department of Medicine, Division of Rheumatic Diseases, Case Western Reserve University School of Medicine and University Hospitals Case Medical Center, Cleveland, Ohio USA 2 Department of Anatomy, Case Western Reserve University School of Medicine and University Hospitals Case Medical Center, Cleveland, Ohio USA * Corresponding author: Malemud CJ, Ph.D., Department of Medicine, Division of Rheumatic Diseases, University Hospitals Case Medical Center, Foley Medical Building, Room 207, 2061 Cornell Road, Cleveland, Ohio 44106-5076, USA, Fax: (216) 844-2288, Tel: (216) 536-1945, (216) 844-7846, E-mail: cjm4@cwru.edu Citation: Wylie MA, Meszaros EC, Malemud CJ (2015) he Efect of Interleukin-6-Type Cytokines and Adiponectin on MAPK Activation in the Immortalized Human Chondrocyte C28/I2 Line and Normal Human Chondrocytes. J Cell Biol Histol 1(1): 101 he C28/I2 line of immortalized juvenile human chondrocytes was employed to determine the extent to which recombinant human (rh) interleukin-6 (rhIL-6), the interleukin-6-like cytokine, rh-oncostatin M, and the adipokine, rh-adiponectin, activated extracellular- signal regulated kinase (ERK1/2), p38α mitogen-activated protein kinase (p38α MAPK) and c-Jun-amino-terminal kinase (JNK). Normal human chondrocytes incubated with rhIL-6 were also analyzed for JNK activation. Western blots which were quantiied by the Metamorph® sotware program showed that p38α MAPK and JNK1/2, but not ERK1/2 were constitutively phosphorylated in C28/ I2 chondrocytes. JNK1/2 was constitutively phosphorylated in normal human chondrocytes as well. C28/I2 chondrocytes produced primarily U-p42ERK (U-ERK2) where the ratio of phosphorylated (P) p42ERK to β-actin was signiicantly increased by rh-oncostatin M and rhIL-6, but not by rh-adiponectin. C28/I2 chondrocytes produced one form of unphosphorylated p38α MAPK. However in addition to P-p38α MAPK another form of P-p38α MAPK migrating at approximately 55kDa was also detected. Two forms of JNK migrating at approximately 51kDa and 46kDa which corresponded to JNK2 (p54) and JNK1 (p46), respectively, were produced by C28/ I2 chondrocytes and normal human chondrocytes but an additional form of JNK (approximately 36kDa) was also found in C28/I2 chondrocytes. Although rhIL-6, rhOSM and rhAPN signiicantly reduced the content of U-JNK51kDa and U-JNK46kDa, none of these cytokines signiicantly activated JNK51kDa or JNK46kDa. Overall, these results implicated rhIL-6, and rh-oncostatin M in activating p42ERK by C28/I2 chondrocytes. hese results may be helpful in deining genes regulated by IL-6-type cytokines in these cells. Abstract Keywords: Chondrocytes; IL-6-type cytokines; Gene’s regulation; Rheumatoid arthritis List of Abbreviations: rhAPN: Recombinant human adiponectin; rhTNF-α: Recombinant human tumor necrosis factor-α; rhIL-6: Recombinant human interleukin-6; rhOSM: Recombinant human oncostatin M; ERK1/2: Extracellular Signal-Regulated Kinase1/2; JNK: c-Jun-NH 2 -terminal Kinase; MAPK: Mitogen-Activated Protein Kinase; MEK1/2: Mitogen-Activated Protein Kinase Kinase1/2; MMP: Matrix metalloproteinase; STAT: Signal Transducers and Activators of Transcription Rheumatoid arthritis (RA) is a debilitating chronic inlammatory disease of synovial joints which over time ultimately alters the structure of articular cartilage and subchondral bone resulting in joint destruction. Over the past 15 years or so diferent clinical approaches to the treatment of RA with a pro-inlammatory cytokine receptor antagonist fusion protein, small molecule inhibitors, and anti-cytokine receptor monoclonal antibodies have been employed. hese drugs were developed by identifying molecular targets which are key mediators in the pathogenesis and progression of RA [1-4]. However, there is much more to be learned about the signal transduction pathways involved in the initiation and progression of RA, especially how dysfunctional signal transduction alters articular chondrocyte homeostasis [5,6]. A further analysis of signal transduction may also reveal potential novel molecular targets for pharmacological intervention in RA necessary for inducing apoptosis of activated T- and B-cells, dendritic cells, neutrophils, macrophages and synoviocytes, while minimizing or inhibiting chondrocyte and osteocyte apoptosis [6-9].