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Endothelial Calmodulin and CaMKII Play a Role in Leukocyte Transmigration
Author(s) -
Dalal Prarthana J,
Sullivan David P,
Muller William A
Publication year - 2019
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.2019.33.1_supplement.375.5
Subject(s) - calmodulin , iqgap1 , microbiology and biotechnology , calcium , chemistry , endothelial stem cell , biology , biochemistry , signal transduction , scaffold protein , in vitro , organic chemistry
Inflammation results in the dilation of blood vessels and recruitment of circulating leukocytes into damaged tissues for repair. A transient increase in endothelial cytosolic free calcium (↑[Ca 2+ ] i ) is required for leukocyte transendothelial migration (TEM). We have also found that IQ‐domain GTPase‐activating protein 1 (IQGAP1) is essential for TEM. Specifically, the calmodulin‐binding isoleucine‐glutamine (IQ) motif domain is critical for its function during TEM. Calmodulin (CaM) is an intracellular calcium‐binding protein, however, its role in TEM is undescribed. Therefore, we hypothesized that it is involved in the endothelial calcium signaling cascade essential for supporting leukocyte transmigration. In endothelial cells IQGAP1 knockdown reduced TEM substantially. Re‐expressing IQGAP1 truncation mutants containing both the actin‐binding and IQ‐motif domains rescued TEM but truncation mutants lacking the IQ motif domain but did not support TEM. Human endothelial cells treated with the calmodulin inhibitor trifluoperazine (TFP) demonstrated a marked reduction in leukocyte TEM. Only 13% of leukocytes transmigrated through endothelial monolayers pretreated with 100 mM TFP compared to 84% TEM in control, untreated monolayers (p<0.05). We also looked at the role of calmodulin kinase II (CaMKII). Treating endothelial monolayers with 10 mM KN‐93, a CaMKII inhibitor, substantially reduced leukocyte TEM. Here 22% of leukocytes transmigrated which was significantly reduced compared to control TEM rates (p<0.05). Calmodulin pulldowns also showed that without the IQ‐motif domain IQGAP1 cannot substantially interact with calmodulin further suggesting a link between endothelial calcium, IQGAP1 and CaM. Current experiments focus on inhibiting CaM and CaMKII in endothelial cells using genetically encoded selective inhibitory peptides and inducible endothelial‐specific CaMKII‐deficient mice. Identifying the mechanism by which endothelial Ca 2+ influx mediates TEM will provide novel insight into the signaling and also provide potential targets for anti‐inflammatory therapy. Support or Funding Information R01 HL046849, R01 HL064774, F30 HL134202 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .