Tumor Necrosis Factor- Induces Nuclear Factor- B-dependent TRPC1 Expression in Endothelial Cells

Yale University, New Haven, Connecticut, United States
Journal of Biological Chemistry (Impact Factor: 4.57). 10/2003; 278(39):37195-203. DOI: 10.1074/jbc.M304287200
Source: PubMed


We investigated the role of tumor necrosis factor-α (TNF-α) in activating the store-operated Ca2+ channels in endothelial cells via the expression of transient receptor potential channel (TRPC) isoforms. We observed that
TNF-α exposure of human umbilical vein endothelial cells resulted in TRPC1 mRNA and protein expression, whereas it had no
effect on TRPC3, TRPC4, or TRPC5 expression. The TRPC1 expression was associated with increased Ca2+ influx after intracellular Ca2+ store depletion with either thrombin or thapsigargin. We cloned the 5′-regulatory region of the human TRPC1 (hTRPC1) gene which contained a TATA box and CCAAT sequence close to the transcription initiation site. We also identified four nuclear
factor-κB (NF-κB)-binding sites in the 5′-regulatory region. To address the contribution of NF-κB in the mechanism of TRPC1
expression, we determined the effects of TNF-α on expression of the reporter luciferase after transfection of hTRPC1 promoter-luciferase (hTRPC1-Pro-Luc) construct in the human dermal microvascular endothelial cell line. Reporter activity
increased >4-fold at 4 h after TNF-α challenge. TNF-α-induced increase in reporter activity was markedly reduced by co-expression
of either kinase-defective IKKβ kinase mutant or non-phosphorylatable IκB mutant. Treatment with NEMO-binding domain peptide,
which prevents NF-κB activation by selectively inhibiting IKKγ interaction with IKK complex, also blocked the TNF-α-induced
TRPC1 expression. Thus, TNF-α induces TRPC1 expression through an NF-κB-dependent pathway in endothelial cells, which can
trigger augmented Ca2+ entry following Ca2+ store depletion. The augmented Ca2+ entry secondary to TRPC1 expression may be an important mechanism of endothelial injury induced by TNF-α.

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Available from: Arshad Rahman, Nov 19, 2015
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    • "Together these data suggest that the NF-kB cascade is involved in up-regulating TRPC1 and TRPC6 expression in PC12 cells. In support of this, it has been reported that tumor necrosis factor a up-regulates TRPC1 expression in endothelial cells via an NF-kB-dependent pathway (Paria et al., 2003). However, we cannot rule out the possibility that IKK 2 regulates TRPC expression through an NF-kB independent mechanism (Chariot, 2009). "
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    ABSTRACT: Transient Receptor Potential Canonical (TRPC) channels are implicated in modulating neurite outgrowth. The expression pattern of TRPCs changes significantly during brain development, suggesting that fine-tuning TRPC expression may be important for orchestrating neuritogenesis. To study how alterations in the TRPC expression pattern affect neurite outgrowth, we used nerve growth factor (NGF)-differentiated rat pheochromocytoma 12 (PC12) cells, a model system for neuritogenesis. In PC12 cells, NGF markedly up-regulated TRPC1 and TRPC6 expression, but down-regulated TRPC5 expression while promoting neurite outgrowth. Overexpression of TRPC1 augmented, whereas TRPC5 overexpression decelerated NGF-induced neurite outgrowth. Conversely, shRNA-mediated knockdown of TRPC1 decreased, whereas shRNA-mediated knockdown of TRPC5 increased NGF-induced neurite extension. Endogenous TRPC1 attenuated the anti-neuritogenic effect of overexpressed TRPC5 in part by forming the heteromeric TRPC1-TRPC5 channels. Previous reports suggested that TRPC6 may facilitate neurite outgrowth. However, we found that TRPC6 overexpression slowed down neuritogenesis, whereas dominant negative TRPC6 (DN-TRPC6) facilitated neurite outgrowth in NGF-differentiated PC12 cells. Consistent with these findings, hyperforin, a neurite outgrowth promoting factor, decreased TRPC6 expression in NGF-differentiated PC12 cells. Using pharmacological and molecular biological approaches, we determined that NGF up-regulated TRPC1 and TRPC6 expression via a p75(NTR)-IKK(2)-dependent pathway that did not involve TrkA receptor signaling in PC12 cells. Similarly, NGF up-regulated TRPC1 and TRPC6 via an IKK(2) dependent pathway in primary cultured hippocampal neurons. Thus, our data suggest that a balance of TRPC1, TRPC5, and TRPC6 expression determines neurite extension rate in neural cells, with TRPC6 emerging as an NGF-dependent "molecular damper" maintaining a submaximal velocity of neurite extension.
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    • "Relatively little is known about the control of TRPC1 gene expression other than that there is regulation by NFκB, HIF-1 and Ca2+ [16-18]. Splice variation of TRPC1 transcripts has been reported but there has been little investigation of the topic and so the extent and importance are unknown. "
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    ABSTRACT: Transient Receptor Potential Canonical 1 (TRPC1) is a widely-expressed mammalian cationic channel with functional effects that include stimulation of cardiovascular remodelling. The initial aim of this study was to investigate variation in TRPC1-encoding gene transcripts. Extensive TRPC1 transcript alternative splicing was observed, with exons 2, 3 and 5-9 frequently omitted, leading to variants containing premature termination codons. Consistent with the predicted sensitivity of such variants to nonsense-mediated decay (NMD) the variants were increased by cycloheximide. However it was notable that control of the variants by NMD was prominent in human embryonic kidney 293 cells but not human vascular smooth muscle cells. The cellular difference was attributed in part to a critical protein in NMD, up-frameshift-1 (UPF1), which was found to have low abundance in the vascular cells. Rescue of UPF1 by expression of exogenous UPF1 was found to suppress vascular smooth muscle cell proliferation. The data suggest: (i) extensive NMD-sensitive transcripts of TRPC1; (ii) inefficient clearance of aberrant transcripts and enhanced proliferation of vascular smooth muscle cells in part because of low UPF1 expression.
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    • "Recently, Du et al. reported that angiotensin II could induce Ca 2+ signaling in glomerular mesangial cells, and TRPC1 had an important role in this process [7]. In addition, there is evidence that the binding sites of NF-kB are located in the 5 0 -regulatory region of the TRPC1 gene [24] [30]. NFkB is retained in the cytoplasm of cells by an inhibitor subunit, inhibitor of kB (IkB), until cell stimulation results in the sequential phosphorylation, ubiquitination, and degradation of IkB. "
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    ABSTRACT: Endothelial dysfunction is associated with cardiovascular diseases. The Ca2+ influx occurring via activation of plasmalemma Ca2+ channels was shown to be critical in signaling the increase in endothelial permeability in response to a variety of permeability-increasing mediators. It has been reported that angiotensin II (AngII) could induce Ca2+ signaling in some cells, and transient receptor potential canonical 1 (TRPC1) had an important role in this process. The objective of this study was to examine the mechanism of AngII-induced Ca2+ entry and vascular endothelial hyperpermeability. Human umbilical vein endothelial cells (HUVECs) exposed to AngII exhibited dose-dependent increase in [Ca2+]i and endothelial permeability. Quantitative real-time RT-PCR and Western blotting showed that the level of TRPC1 expression had increased significantly at 12h and at 24h after treatment of HUEVCs with AngII. The expression of p65 was suppressed using an RNAi strategy. The results showed that the NF-κB signaling pathway and type-1 receptor of AngII was involved in AngII-induced TRPC1 upregulation. Moreover, knockdown of TRPC1 and NF-κB expression attenuates AngII-induced [Ca2+]i and endothelial permeability. NF-κB and TRPC1 have critical roles in AngII-induced Ca2+ entry and endothelial permeability.
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