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Synergistic regulation of the acute phase protein SIP24/24p3 by glucocorticoid and pro-inflammatory cytokines

Liu Quansheng, Marit Nilsen-Hamilton, Xiong Sidong

Department of Immunology and Key Laboratory of Molecular Medicine of Ministry of Education, Shanghai Medical College of Fudan University

Abstract

SIP24/24p3 is a secreted murine acute phase protein which has been speculated to play an anti-inflammatory role in vivo. Recently SIP24/24p3 has been found to be able to specifically induce apoptosis in leukocytes. By using 35S metabolic labeling method, we studied the regulation of SIP24/24p3 by glucocorticoid and pro-inflammatory cytokines IL-6 and TNF-α in cultured Balb/c 3T3 and BNL cells. The following results were observed: ( 1 ) dexamethasone induced the expression of SIP24/24p3 in both Balb/c 3T3 and BNL cells, the induction was more significant in BNL cells; (2) dexamethasone and IL-6 synergistically induced the expression of SIP24/24p3 in both Balb/c 3T3 and BNL cells; (3) in Balb/c 3T3 cells dexamethasone and TNF-a acted synergistically to induce the expression of SIP24/24p3, whereas in BNL cells dexamethasone and TNF-α induced the expression of SIP24/24p3 in an additive manner; (4) dexamethasone and IL-6/TNF-α acted synergistically in Balb/c 3T3 cells and additively in BNL cells to induce the expression of SIP24/24p3. The inducibility of SIP24/24p3 by multiple factors will help to explain its highly specific expression in vivo. The difference in the expression patterns of SIP24/24p3 in different cell types is also suggestive to its expression and regulation in hepatic and extrahepatic tissues. Finally, the fact that SIP24/24p3 protein can be induced by both pro-inflammatory as well as anti-inflammatory factors is indicative of the important role of SIP24/24p3 in the entire acute phase response process.

Key words: Murine acute phase protein SIP24/24p3;35S metabolic labeling;Dexamethasone; IL-6;TNF-α

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Citing This Article：

Liu Quansheng, Marit Nilsen-Hamilton, Xiong Sidong. Synergistic regulation of the acute phase protein SIP24/24p3 by glucocorticoid and pro-inflammatory cytokines. Acta Physiol Sin 2003; 55 (5): (in Chinese with English abstract).