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LPS/TLR4‐NF‐[kappa]B axis signaling amplifies STIM1 expression to augment PAR‐1‐induced Calcium entry and permeability response in lung microvessels
Author(s) -
DEBROY AUDITI,
Sundivakkam Premanand,
Singh Vandana,
Malik Asrar B,
Tiruppathi Chinnaswamy
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.571.2
Subject(s) - stim1 , microbiology and biotechnology , tlr4 , transcription factor , activator (genetics) , vascular permeability , chemistry , ap 1 transcription factor , nfkb1 , biology , signal transduction , receptor , endocrinology , gene , endoplasmic reticulum , biochemistry
Rationale Human sepsis is characterized by lung microvascular leakage. Store‐operated Calcium Entry (SOCE) in endothelial cells (ECs) mediates increase in lung vascular permeability. Here we investigated the role of the transcription factor NF‐κB, activated downstream of TLR4 in mediating the expression of the crucial activator of SOCE, Stromal Interacting Molecule 1 (STIM1), and its consequences on PAR‐1‐mediated Ca 2+ entry in ECs and lung vascular leak. Results LPS induced STIM1 expression in lung ECs. Increased STIM1 expression was associated with augmented PAR‐1‐mediated SOCE and permeability increase. These results were recapitulated in vivo mouse model LPS‐induced sepsis and the response was abrogated in TLR4 knockout mice. To characterize the transcriptional mechanism of LPS induction of STIM1, we analyzed the 5′‐regulatory region of STIM1 gene and found the consensus binding sites for LPS‐sensitive transcription factors NF‐κB, SP1, and AP1. By electrophoretic mobility shift assay, we observed the binding of NF‐κB and SP1 to the h STIM1 promoter. We cloned the h STIM1 promoter and showed LPS induction of promoter activity in ECs. Silencing of p65/RelA markedly reduced LPS‐induced STIM1 expression and subsequent PAR‐1 responses in ECs. Conclusion These results collectively suggest the novel and critical role of STIM1 in mediating lung vascular hyper‐permeability during gram‐negative sepsis.