The Transcription Factor C/EBP-β Mediates Constitutive and LPS-Inducible Transcription of Murine SerpinB2

Abstract

SerpinB2 or plasminogen activator inhibitor type 2 (PAI-2) is highly induced in macrophages in response to inflammatory stimuli and is linked to the modulation of innate immunity, macrophage survival, and inhibition of plasminogen activators. Lipopolysaccharide (LPS), a potent bacterial endotoxin, can induce SerpinB2 expression via the toll-like receptor 4 (TLR4) by ∼1000-fold over a period of 24 hrs in murine macrophages. To map the LPS-regulated SerpinB2 promoter regions, we transfected reporter constructs driven by the ∼5 kb 5'-flanking region of the murine SerpinB2 gene and several deletion mutants into murine macrophages. In addition, we compared the DNA sequence of the murine 5′ flanking sequence with the sequence of the human gene for homologous functional regulatory elements and identified several regulatory cis-acting elements in the human SERPINB2 promoter conserved in the mouse. Mutation analyses revealed that a CCAAT enhancer binding (C/EBP) element, a cyclic AMP response element (CRE) and two activator protein 1 (AP-1) response elements in the murine SerpinB2 proximal promoter are essential for optimal LPS-inducibility. Electrophoretic mobility shift (EMSA) and chromatin immunoprecipitation (ChIP) assays demonstrated that LPS induces the formation of C/EBP-β containing complexes with the SerpinB2 promoter. Importantly, both constitutive and LPS-induced SerpinB2 expression was severely abrogated in C/EBP-β-null mouse embryonic fibroblasts (MEFs) and primary C/EBP-β-deficient peritoneal macrophages. Together, these data provide new insight into C/EBP-β-dependent regulation of inflammation-associated SerpinB2 expression.

eIF4E-Binding Proteins 1 and 2 Limit Macrophage Anti-Inflammatory Responses through Translational Repression of IL-10 and Cyclooxygenase-2

“…We predicted that amplified PGE 2 -C/EBPb signaling would promote this cellular response in 4E-BP1/2 DKO BMDM. We focused on Arg1 and SerpinB2 because these genes are transcriptionally activated via C/EBPb in LPS-stimulated macrophages and have central roles in local homeostasis (45,46). Arginase-1 functions as an inhibitor of chronic inflammation in Th2-polarized immune responses (47), and SerpinB2 suppresses Th1 responses during inflammatory processes (48).…”

Dual-specificity phosphatase 5 regulates nuclear ERK activity and suppresses skin cancer by inhibiting mutant Harvey-Ras (HRas Q61L )-driven SerpinB2 expression

“…S5C), indicating that Egr1 may mediate SerpinB2 expression. We used SerpinB2 promoterreporter constructs (19) to analyze TPA-induced transcription in WT and KO MEFs, finding that reporter activity was greatly increased in KO MEFs compared with WT cells (Fig. S5D).…”

SERPINB2 is regulated by dynamic interactions with pause-release proteins and enhancer RNAs

“…SERPINB2 has been implicated in Th2 responses where it is regulated by STAT6 [10]. Other recognized transcriptional regulators include NFκB, AP-1 and C/EBPβ [11, 12]. Histone deacetylase inhibitors modulate SERPINB2 expression but the epigenetic control of expression has not been previously investigated [13].…”