We are working with a synovial factor which induces the synthesis and secretion of prostaglandin E (PGE) and several neutral proteinases, including collagenase, by monolayers of cultured articular chondrocytes. The chondrocyte activating factor (CAF) which does this is closely related to, if not not identical with, catabolin and interleukin-1 (IL-1). The mechanism of chondrocyte activation is completely unknown. From what is known of stimulus-coupled cellular activation in other systems, we may suspect one of several mechanisms. One such mechanism involves binding of the agonist to the plasma membrane with subsequent mediation of a second messenger such as Ca, cyclic AMP or cyclic GMP, producing the activation of one or more protein kinases. Another involves the acquisition of direct protein kinase activity by the receptor in the plasma membrane once it binds the agonist. Certain agents, such as the steroid hormones, penetrate the cell and travel to the nucleus. Along these lines, we will determine the type of mechanism through which chondrocytes are activated by our synovial CAF. Complementary experiments will be conducted with IL-1. Binding studies will be performed to determine whether activation is mediated via a cell surface receptor. To determine whether a """"""""classical"""""""" second messenger is involved in signal transduction, we will measure possible fluxes in the cytosolic concentrations of Ca, cGMP and cAMP during activation. Possible mediation of these second messengers will also be examined through the use of specific stimulators and inhibitors of these putative intermediaries. If these experiments fail to identify a classical second messenger, the possibility that the receptor gains protein kinase activity upon binding CAF or IL-1 will be addressed. This information will help to identify ways of therapeutically preventing chondrocyte activation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
1R01AR036891-01A1
Application #
3157802
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Project Start
1986-12-01
Project End
1989-11-30
Budget Start
1986-12-01
Budget End
1987-11-30
Support Year
1
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Type
Schools of Medicine
DUNS #
053785812
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Bandara, G; Lin, C W; Georgescu, H I et al. (1992) The synovial activation of chondrocytes: evidence for complex cytokine interactions involving a possible novel factor. Biochim Biophys Acta 1134:309-18
Hulkower, K I; Sagi-Eisenberg, R; Traub, L M et al. (1992) Synovial protein kinase C and its apparent insensitivity to interleukin-1. Eur J Biochem 209:81-8
Hulkower, K I; Evans, C H (1991) Protein phosphorylation and metalloproteinase synthesis by lapine articular chondrocytes. J Rheumatol Suppl 27:110-3
Hulkower, K I; Sagi-Eisenberg, R; Traub, L M et al. (1991) Interleukin-1 and synovial protein kinase C: identification of a novel, 35 kDa cytosolic substrate. Agents Actions 34:278-81
Hulkower, K I; Georgescu, H I; Evans, C H (1991) Evidence that responses of articular chondrocytes to interleukin-1 and basic fibroblast growth factor are not mediated by protein kinase C. Biochem J 276 ( Pt 1):157-62
Hulkower, K I; Georgscu, H I; Evans, C H (1989) Altered patterns of protein phosphorylation in articular chondrocytes treated with interleukin-1 or synovial cytokines. FEBS Lett 257:228-32
Lin, C W; Georgescu, H I; Phillips, S L et al. (1989) Cycloheximide inhibits the induction of collagenase mRNA in chondrocytes exposed to synovial factors or recombinant interleukin-1. Agents Actions 27:445-7
Hulkower, K I; Georgescu, H I; Evans, C H (1989) Protein kinase C and chondrocyte activation. Agents Actions 27:442-4
Bandara, G; Lin, C W; Georgescu, H I et al. (1989) Chondrocyte activation by interleukin-1: analysis of the synergistic properties of fibroblast growth factor and phorbol myristate acetate. Arch Biochem Biophys 274:539-47
Bandara, G; Lin, C W; Georgescu, H I et al. (1989) Chondrocyte activation by interleukin-1: synergism with fibroblast growth factor and phorbol myristate acetate. Agents Actions 27:439-41

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