Receptor-activated Ca2+ influx: how many mechanisms for how many channels?

Fasolato, Cristina; Innocenti, Barbara; Pozzan, Tullio

doi:10.1016/0165-6147(94)90282-8

Cited by 405 publications

(293 citation statements)

References 52 publications

Supporting

Mentioning

282

Contrasting

Unclassified

Order By: Relevance

“…Recently, a lot of interest has focused on the question whether the trp (transient receptor potential) channel from Drosophila photoreceptors or one of its mammalian homologues is similar or identical to the CRAC channel [1,2,7]. It has been suggested that trp is a store-operated Ca 2+ channel and it has been shown that trp channels expressed in Sf9 cells or Xenopus oocytes could be activated by thapsigargin [24,27,29].…”

Section: Discussionmentioning

confidence: 99%

Depletion of intracellular calcium stores activates an outward potassium current in mast and RBL‐1 cells that is correlated with CRAC channel activation

Hoth

1996

FEBS Letters

View full text Add to dashboard Cite

Highly Ca 2+ selective Ca 2+ channels activated by store depletion have been recently described in several cell types and have been termed CRAC channels (for calcium releaseactivated calcium). The present study shows that following store depletion in mast and RBL-I cells, monovalent outward currents could be recorded if the internal solution contained K + but not Cs +. The activation of the outward K + current correlated with the activation of ICRAC, in both time and amplitude, suggesting that the K + current might be carried by CRAC channels. The amplitude of the outward current was increased if external Ca z+ was reduced or replaced by external Ba 2+. The outward K + conductance might have a physiological role in maintaining the driving force for Ca 2+ entry during the activation of CRAC channels.

show abstract

Section: Discussionmentioning

confidence: 99%

Depletion of intracellular calcium stores activates an outward potassium current in mast and RBL‐1 cells that is correlated with CRAC channel activation

Hoth

1996

FEBS Letters

View full text Add to dashboard Cite

show abstract

“…Although studies using either luorescent Ca 2+ indicators or electrophysiological techniques lave suggested that multiple types of Ca 2+ permeant channels nay be involved in different cell types to fulfill the influx funcion, the molecular structure of the channels and the mechalism that regulates the influx have remained unclear and reprerent one of the major unanswered questions of cellular Ca -,+ !lomeostasis [3][4][5].…”

Section: ~ Introductionmentioning

confidence: 99%

Molecular cloning of a widely expressed human homologue for the Drosophila trp gene

et al. 1995

View full text Add to dashboard Cite

The Drosophila transient receptor potential (trp) gene and its homologue, trpl, have been suggested to mediate calcium entry during the insect's phototransduction process. We isolated human cDNA, human trp-1 (Htrp-1), encoding a polypeptide .f 793 amino acids that is 37% identical (62% similar) to Drosophila trp and trpl. Northern analysis showed that the Htrp-1 transcript is approximately 5.5 kb and expressed in most human tissues, with higher amounts in ovary, testis, heart, and brain.Isolation of Htrp-I suggests that a trp-type protein is present in mammals and should provide a useful tool in studying calciumdepletion induced calcium influx processes.:~ey words': Transient receptor potential; Calcium influx , hannel; Ca 2+ signaling ~. IntroductionCalcium regulation plays an important role in many cellular 0rocesses. In non-excitable mammalian cells, activation of i~hosphoinositide-specific phospholipase C (PLC) produces ~nositol 1,4,5-trisphosphate (IP3), which in turn causes the reease of intracellular calcium from its storage pools in the endo~lasmic reticulum. This results in a transient elevation of cyosolic-free Ca 2+, which is normally followed by a Ca 2+ influx 'rom the extracellular space. By refilling the pools, Ca 2+ influx )lays an important role in prolonging the Ca 2+ signal, allowing or localized signaling, and maintaining Ca 2÷ oscillations [1].Calcium influx in non-excitable cells is thought to occur hrough plasma membrane channels which, in contrast to the voltage-dependent Ca 2+ channels in excitable cells, are operated lot by changes of membrane potentials but rather by how full he internal Ca 2+ stores are [2]. Although studies using either luorescent Ca 2+ indicators or electrophysiological techniques lave suggested that multiple types of Ca 2+ permeant channels nay be involved in different cell types to fulfill the influx funcion, the molecular structure of the channels and the mechalism that regulates the influx have remained unclear and reprerent one of the major unanswered questions of cellular Ca -,+ !lomeostasis [3][4][5].Candidates involved in voltage-independent Ca 2+ entry into [9]. A detailed analysis of the trpl sequence showed that it shares moderate homology with voltage-dependent Ca 2+ and Na ÷ channels at their putative transmembrane regions. However, in clear contrast with the voltage-dependent channels, it lacks the positively charged amino acid residues at the presumed $4 segment which are thought to act as voltage sensors that promote gating in response to changes in membrane potentials. The structural homology to Ca 2+ and Na + channels together with the absence of charged residues in trpl and trp suggested that these proteins may form voltage-independent ion channels. This was demonstrated recently by expression of the cDNAs for trp and trpl in insect Sf9 cells using the baculovirus system. It was fount that trp forms a Ca 2÷ permeable cation channel which is activated by store depletion with thapsigargin [10] whereas trpl forms a Ca -'+ permeable non-selec...

show abstract

“…Two explanations for the primaquine-induced inhibition of Ins(1,4,5)P $ F-stimulated Ca# + inflow (assessed by measurement of the initial rate of Ca# + oinduced increase in fluo-3 fluorescence) are that primaquine either directly inhibits the flow of Ca# + through open SACCs or that it inhibits the process by which Ca# + release from the SER activates SACCs. In relation to the second explanation, it has been proposed that the activation of SACCs by Ca# + release from the SER involves the movement of vesicles that contain SACCs to the plasma membrane and insertion of SACCs into the plasma membrane by fusion of the vesicle and the plasma membranes [2,9]. Inactivation of SACCs might then involve endocytotic retrieval from the plasma membrane [9].…”

Section: Action Of Primaquinementioning

confidence: 99%

“…On the basis of cation specificity and the likely mechanism of activation, three groups of receptor-activated Ca# + channels have been identified : ligand-gated channels, intracellular messenger-activated channels and store-activated channels [2]. The last-mentioned process, initially described by Putney [3], involves the release of Ca# + from a component of the smooth endoplasmic reticulum (SER), which in turn leads to activation of Ca# + inflow across the plasma membrane.…”

Section: Introductionmentioning

confidence: 99%

“…Three mechanisms have emerged to explain how the release of Ca# + from a region of the SER leads to activation of the plasma membrane SACCs. These are : (1) conformational coupling between one or more proteins in the SER and the SACCs [5], (2) the formation and action of a mobile intracellular messenger [6][7][8], and (3) the transport of vesicles containing SACCs from an intracellular site to the plasma membrane where the SACCs are inserted into the plasma membrane by fusion of the vesicle and plasma membranes [2,9] (compare the insertion of glucose . It is concluded that membrane fusion processes are unlikely to be involved in the link between the release of Ca# + from the endoplasmic reticulum and activation of SACCs.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Store-activated Ca2+ inflow in Xenopus laevis oocytes: inhibition by primaquine and evaluation of the role of membrane fusion

Gregory

Barritt

1996

Biochemical Journal

View full text Add to dashboard Cite

The role of membrane fusion in the activation of store-activated Ca2+ channels (SACCs) in the plasma membrane of Xenopus laevis oocytes was investigated with primaquine, an inhibitor of vesicle trafficking, reagents that disrupt the cytoskeleton, and reagents that activate or inhibit the functions of monomeric and trimeric GTP-binding regulatory proteins. Ca2+ inflow was assessed by measuring the rate of increase in the fluorescence of the intracellular Ca2+ chelator fluo-3 after the addition of extracellular Ca2+ to oocytes previously incubated in the absence of added Ca2+. Primaquine inhibited the 3-deoxy-3-fluoro-Ins(1,4,5)P3 (Ins(1,4,5)P3F)-stimulated increase in Ca2+o-induced fluo-3 fluorescence with no detectable effect on the release of Ca2+ from intracellular stores. The effect of primaquine was observed within 1.5 min, showed similarity to the inhibition induced by Gd3+, was reversible, and was observed when primaquine was added either before or after activation of the SACCs. The degree of inhibition of Ca2+ inflow by primaquine was halved when the extracellular concentration of Ca2+ was increased from 3.1 to 12.5 mM. Primaquine also inhibited Ca2+ inflow through cholera toxin-activated divalent cation channels and Drosophila Trpl channels (expressed in oocytes after injection of trpl cRNA). These results indicate that primaquine inhibits open SACCs, possibly by directly inhibiting Ca2+ flow through the channel pore. Colchicine plus cytochalasin B, Brefeldin A, the peptide Arf-1 (2–17) (introduced by microinjection), lovastatin or pertussis toxin did not inhibit the Ins(1,4,5)P3F-stimulated increase in fluo-3 fluorescence. In contrast, guanosine 5´-[γ-thio]triphosphate (GTP[S]), guanosine 5´-[β,γ-imido]triphosphate (p[NH]ppG) and AlF4-, but not guanosine 5´-[β-thio]diphosphate, inhibited the Ins(1,4,5)P3F-stimulated increase in fluo-3 fluorescence. Co-administration of GTP did not prevent the inhibition by GTP[S] or AlF4-. Staurosporine largely prevented the inhibition of store-activated Ca2+ inflow by GTP[S]. It is concluded that membrane fusion processes are unlikely to be involved in the link between the release of Ca2+ from the endoplasmic reticulum and activation of SACCs. The idea that this link is achieved by direct interaction of a protein(s) in the endoplasmic reticulum membrane with the SACC protein is briefly discussed.

show abstract

Receptor-activated Ca2+ influx: how many mechanisms for how many channels?

Cited by 405 publications

References 52 publications

Depletion of intracellular calcium stores activates an outward potassium current in mast and RBL‐1 cells that is correlated with CRAC channel activation

Depletion of intracellular calcium stores activates an outward potassium current in mast and RBL‐1 cells that is correlated with CRAC channel activation

Molecular cloning of a widely expressed human homologue for the Drosophila trp gene

Store-activated Ca2+ inflow in Xenopus laevis oocytes: inhibition by primaquine and evaluation of the role of membrane fusion

Contact Info

Product

Resources

About