Trp proteins form store‐operated cation channels in human vascular endothelial cells

123

Stimulation of the T-cell receptor (TCR) activatesCa 2؉ entry across the plasma membrane, which is a key triggering event for the T-cell-associated immune response. We show that TRPC3 channels are important for the TCR-dependent Ca 2؉ entry pathway. The TRPC3 gene was found to be damaged in human T-cell mutants defective in Ca 2؉ influx. Mutations of the TRPC3 gene were accompanied by changes of TRPC3 gene expression. Introduction of the complete human TRPC3 cDNA into those mutants rescued Ca 2؉ currents as well as TCR-dependent Ca 2؉ signals. Our data provide the initial step toward understanding the molecular nature of endogenous Ca 2؉ channels participating in T-cell activation and put forward TRPC3 as a new target for modulating the immune response.

Section: Discussionsupporting

confidence: 68%

TRPC3 Mediates T-cell Receptor-dependent Calcium Entry in Human T-lymphocytes

Philipp¹,

Strauß

Hirnet

et al. 2003

123

“…3 The TRPC6 channel expressed in PC12D cells is the TRPC6B isoform, 3 which lacks 54 amino acid residues present in the amino terminus of the TRPC6A isoform (33). Carbachol-stimulated Ba 2ϩ influx in PC12D cells is blocked by exogenous expression of anti-TRPC6 mRNA or the amino-terminal domain of TRPC6B, 3 which may act in a dominantnegative manner to block TRPC6 channel assembly (36,37). Fig.…”

Section: Activation Of M1 Machrs Activates Endogenous Trpc6mentioning

confidence: 99%

Activation of M1 Muscarinic Acetylcholine Receptors Stimulates the Formation of a Multiprotein Complex Centered on TRPC6 Channels

Kim

Saffen

2005

In this study we showed that stimulation of M1 muscarinic acetylcholine receptors (mAChRs) activates endogenous transient receptor potential-canonical, subtype 6 (TRPC6), channels in neuronal PC12D cells. Activation of TRPC6 channels is correlated with the formation of a multiprotein complex containing M1 mAChRs, TRPC6 channels, and protein kinase C (PKC). ) in the channels; or 3) pretreatment with FK506 or rapamycin, immunosuppressants that directly bind FKBP12. Inhibition of FKBP12 binding blocks the dephosphorylation of TRPC6 channels and the disassociation of M1 mAChRs, without affecting disassociation of PKC. The calcineurin inhibitor cyclosporin A also blocks the dephosphorylation of TRPC6 and prevents the disassociation of M1 mAChRs. Together, these results show that activated TRPC6 channels form the center of a dynamic multiprotein complex that includes PKC and calcineurin, which respectively phosphorylate and dephosphorylate the channels. Phosphorylation of the TRPC6 channels by PKC is required for the binding of FKBP12, which in turn is required for the binding of calcineurin and calmodulin. Subsequent dephosphorylation of the channels by calcineurin is required for the disassociation of M1 mAChRs.

“…The contribution of Na ϩ /Ca 2ϩ exchange is likely to vary, depending on the ability of a physiological stimulus to induce Na ϩ loading (36). The recent demonstration of an inositol 1,4,5-trisphosphate-dependent, endothelial Na ϩ permeability suggests that various hormones or neurotransmitters are able to affect endothelial Na ϩ gradients (43). In pathophysiological situations such as oxidative stress, excessive Na ϩ entry via redox-activated cation channels has been observed (44,45).…”

Section: Role Of Namentioning

confidence: 99%

Na+/Ca2+ Exchange Facilitates Ca2+-dependent Activation of Endothelial Nitric-oxide Synthase

Teubl

Gröschner

Kohlwein³

et al. 1999

Self Cite

-(␤-[3-(4-methoxyphenyl)-propoxy]-4-methoxyphenethyl)-1H-imidazole hydrochloride (SK&F 96365) mimicked the effects of Na؉ loading. The effects of monensin were completely blocked by 3,4-dichlorobenzamil, a potent and selective inhibitor of NCX, whereas the structural analog amiloride, which barely affects Na ؉ /Ca 2؉ exchange, was ineffective. Consistent with a pivotal role of Na ؉ /Ca 2؉ exchange in Ca 2؉ -dependent activation of eNOS, an NCX protein was detected in caveolin-rich membrane fractions containing both eNOS and caveolin-1. These results demonstrate for the first time a crucial role of cellular Na ؉ gradients in regulation of eNOS activity and suggest that a tight functional interaction between endothelial NCX and eNOS may take place in caveolae.