Thrombin selectively engages LIM kinase 1 and slingshot-1L phosphatase to regulate NF-κB activation and endothelial cell inflammation.

Abstract

Endothelial cell (EC) inflammation is a central event in the pathogenesis of many pulmonary diseases such as acute lung injury and its more severe form acute respiratory distress syndrome. Alterations in actin cytoskeleton are shown to be crucial for NF-κB regulation and EC inflammation. Previously, we have described a role of actin binding protein cofilin in mediating cytoskeletal alterations essential for NF-κB activation and EC inflammation. The present study describes a dynamic mechanism in which LIM kinase 1 (LIMK1), a cofilin kinase, and slingshot-1Long (SSH-1L), a cofilin phosphatase, are engaged by procoagulant and proinflammatory mediator thrombin to regulate these responses. Our data show that knockdown of LIMK1 destabilizes whereas knockdown of SSH-1L stabilizes the actin filaments through modulation of cofilin phosphorylation; however, in either case thrombin-induced NF-κB activity and expression of its target genes (ICAM-1 and VCAM-1) is inhibited. Further mechanistic analyses reveal that knockdown of LIMK1 or SSH-1L each attenuates nuclear translocation and thereby DNA binding of RelA/p65. In addition, LIMK1 or SSH-1L depletion inhibited RelA/p65 phosphorylation at Ser(536), a critical event conferring transcriptional competency to the bound NF-κB. However, unlike SSH-1L, LIMK1 knockdown also impairs the release of RelA/p65 by blocking IKKβ-dependent phosphorylation/degradation of IκBα. Interestingly, LIMK1 or SSH-1L depletion failed to inhibit TNF-α-induced RelA/p65 nuclear translocation and proinflammatory gene expression. Thus this study provides evidence for a novel role of LIMK1 and SSH-1L in selectively regulating EC inflammation associated with intravascular coagulation.

• Authors: Antony Leonard, Catherine Marando, Arshad Rahman, Fabeha Fazal
• Journal: American journal of physiology. Lung cellular and molecular physiology (Am J Physiol Lung Cell Mol Physiol) Vol. 305 Issue 9 Pg. L651-64 (Nov 01 2013) ISSN: 1522-1504 [Electronic] United States
• PMID: 24039253 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• CFL1 protein, human
• Cofilin 1
• NF-kappa B
• RELA protein, human
• Transcription Factor RelA
• LIMK1 protein, human
• Lim Kinases
• I-kappa B Kinase
• Phosphoprotein Phosphatases
• SSH1 protein, human
• Thrombin

Topics

• Cell Line
• Cofilin 1 (metabolism)
• Disseminated Intravascular Coagulation (immunology, metabolism)
• Endothelial Cells (cytology, immunology, metabolism)
• Gene Knockdown Techniques
• Humans
• I-kappa B Kinase (metabolism)
• Lim Kinases (genetics, metabolism)
• NF-kappa B (metabolism)
• Phosphoprotein Phosphatases (genetics, metabolism)
• Phosphorylation (physiology)
• Pneumonia (immunology, metabolism)
• Pulmonary Artery (cytology, immunology)
• Thrombin (metabolism)
• Transcription Factor RelA (metabolism)
• Vasculitis (immunology, metabolism)