Epithelium-specific Ets transcription factor-1 acts as a negative regulator of cyclooxygenase-2 in human rheumatoid arthritis synovial fibroblasts.
BACKGROUND
Rheumatoid arthritis (RA) is characterized by excessive synovial inflammation. Cyclooxygenase-2 (COX-2) is an enzyme that catalyzes the conversion of arachidonic acid (AA) into prostaglandins. Epithelium-specific Ets transcription factor-1 (ESE-1) was previously demonstrated to upregulate COX-2 in co-operation with nuclear factor kappa B (NFκB) in macrophages and chondrocytes. However, the role of ESE-1 in RA pathology has remained unclear. In this study, we aimed to elucidate the relationship between ESE-1 and COX-2 in RA synovial fibroblasts (RASFs) using a HD-Ad-mediated knockdown approach.


RESULTS
ESE-1 and COX-2 were induced by IL-1β in RASFs that corresponded with an increase in PGE2. Endogenous levels of ESE-1 and COX-2 in human RASFs were analyzed by RT-qPCR and Western blot, and PGE2 was quantified using competitive ELISA. Interestingly, knockdown of ESE-1 using helper-dependent adenovirus (HD-Ad) led to a significant upregulation of COX-2 at a later phase of IL-1β stimulation. Examination of ESE-1 intracellular localization by nuclear fractionation revealed that ESE-1 was localized in the nucleus, occupying disparate cellular compartments to NFκB when COX-2 was increased. To confirm the ESE-1-COX-2 relationship in other cellular systems, COX-2 was also measured in SW982 synovial sarcoma cell line and ESE-1 knockout (KO) murine macrophages. Similarly, knockdown of ESE-1 transcriptionally upregulated COX-2 in SW982 and ESE-1 KO murine macrophages, suggesting that ESE-1 may be involved in the resolution of inflammation.


CONCLUSIONS
ESE-1 acts as a negative regulator of COX-2 in human RASFs and its effect on COX-2 is NFκB-independent.
SickKids Research Institute, Program in Physiology and Experimental Medicine, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 9th floor, 686 Bay Street, Toronto, ON M5G 0A4 Canada ; Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8 Canada.
Chan-Mi
CM
Lee
The Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria Street, Toronto, ON M5B 1T8 Canada ; Institute of Medical Science, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8 Canada.
Sahil
S
Gupta
The Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria Street, Toronto, ON M5B 1T8 Canada ; Department of Anesthesiology and Intensive Care, The Second Military Medical University, Changhai Hospital, Shanghai, 200433 China.
Jiafeng
J
Wang
Department of Medicine, Division of Rheumatology and Immunology, School of Medicine, Vanderbilt University, 1161 21st Ave S, MCN T-3113, Nashville, TN 37232 USA.
Elizabeth M
EM
Johnson
Department of Medicine, Division of Rheumatology and Immunology, School of Medicine, Vanderbilt University, 1161 21st Ave S, MCN T-3113, Nashville, TN 37232 USA.
Leslie J
LJ
Crofford
The Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria Street, Toronto, ON M5B 1T8 Canada ; Institute of Medical Science, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8 Canada ; Department of Surgery, St. Michael's Hospital, University of Toronto, 30 Bond Street, Toronto, ON M5B 1W8 Canada.
John C
JC
Marshall
Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8 Canada ; Division of Genetics and Development, Toronto Western Research Institute, Toronto Western Hospital, University Health Network (UHN), 60 Leonard Avenue, Toronto, ON M5T 2S8 Canada.
Mohit
M
Kapoor
SickKids Research Institute, Program in Physiology and Experimental Medicine, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 9th floor, 686 Bay Street, Toronto, ON M5G 0A4 Canada ; Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8 Canada ; Institute of Medical Science, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8 Canada.
Jim
J
Hu
COX-2; ESE-1; Helper-dependent adenovirus; Inflammation; Prostaglandins; Rheumatoid arthritis; Synovial fibroblasts