Fas and Fas-associated death domain protein regulate monocyte chemoattractant protein-1 expression by human smooth muscle cells through caspase- and calpain-dependent release of interleukin-1alpha

• Published in: Circulation research Vol. 93; no. 6; pp. 515 - 522
• Main Authors: Schaub, Friedemann J, Liles, W Conrad, Ferri, Nicola, Sayson, Kirsten, Seifert, Ronald A, Bowen-Pope, Daniel F
• Format: Journal Article
• Language: English
• Published: United States Lippincott Williams & Wilkins Ovid Technologies 19-09-2003
• Subjects: Adaptor Proteins, Signal Transducing; Calpain - metabolism; Calpain - physiology; Carrier Proteins - metabolism; Caspases - metabolism; Caspases - physiology; Cells, Cultured; Chemokine CCL2 - biosynthesis; Chemokine CCL2 - genetics; Cycloheximide - pharmacology; Fas Ligand Protein; Fas-Associated Death Domain Protein; Gene Expression Regulation; Humans; Interleukin-1 - biosynthesis; Interleukin-1 - genetics; Interleukin-1 - physiology; Membrane Glycoproteins - pharmacology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - enzymology; Muscle, Smooth, Vascular - immunology; Signal Transduction; Transcription, Genetic - drug effects; Up-Regulation
• ISSN: 0009-7330; 1524-4571

We previously reported that treatment of human vascular smooth muscle cells (SMCs) with proapoptotic stimuli, including Fas ligand plus cycloheximide (FasL/Chx), or overexpression of Fas-associated death domain protein (FADD) result in increased expression of monocyte chemoattractant protein-1 (MCP-1) and other proinflammatory genes. In this study, we demonstrate that Fas/FADD-induced MCP-1 upregulation is driven by an autocrine/paracrine signaling loop in which interleukin (IL)-1alpha synthesis and release are activated through caspase- and calpain-dependent processes. Untreated SMCs contain very little IL-1alpha protein or transcript. Both were increased greatly in response to Fas/FADD activation, primarily through an autocrine/paracrine pathway in which secreted IL-1alpha stimulated additional IL-1alpha synthesis and release. Caspase 8 (Csp8) activity increased in response to FasL/Chx treatment, and Csp8 inhibitors markedly reduced IL-1alpha release and MCP-1 upregulation. In contrast, Csp8 activity was not significantly increased in response to FADD overexpression and caspase inhibitors did not effect FADD-induced MCP-1 upregulation. Both FasL/Chx treatment and FADD overexpression increased the activity of calpains. Calpain inhibitors reduced IL-1alpha release and MCP-1 upregulation in both FADD-overexpressing SMCs and FasL/Chx-treated SMCs without blocking Csp8 activity. This indicates that calpains are not required for activation of caspases and that caspase activation is not sufficient for IL-1alpha release and MCP-1 upregulation. These data suggest that calpains play a dominant role in Fas/FADD-induced IL-1alpha release and MCP-1 upregulation and that caspase activation may function to amplify the effects of calpain activation.