Abnormal calcium transport into microsomes of grey platelet syndrome

Enouf, Jocelyne; Lebret, Maryline; Bredoux, Raymonde; Lévy-Toledano, S; Caen, Jacques P.

doi:10.1111/j.1365-2141.1987.tb04146.x

Cited by 17 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a new case of GPS in Italy, a markedly reduced aggregation and Ca 2+ -mobilization by thrombin was mimicked by peptides activating platelets through the PAR-1 and PAR-4 receptors (15). An abnormal thrombin-induced Ca 2+ -mobilization had been earlier reported for two French (16) and an American patient (17). It is interesting then that TLT-1 ligation has been reported to induce Ca 2+ -mobilization (3).…”

Section: Discussionmentioning

confidence: 54%

Phenotypic heterogeneity in the gray platelet syndrome extends to the expression of TREM family member, TLT-1

Nurden¹,

Nurden²,

Bermejo³

et al. 2008

Thromb Haemost

View full text Add to dashboard Cite

The Gray platelet syndrome (GPS) is a rare inherited disorder linked to undefined molecular abnormalities that prevent the formation and maturation of α-granules. Here, we report studies on two patients from unrelated families that confirm phenotypic heterogeneity in the disease. First we used immunoelectron microscopy (I-EM) to confirm that TREM-like transcript-1 (TLT-1) is mostly localized to α-granule membranes of normal platelets. Then we performed Western blotting (WB) and flow cytometry with permeabilized platelets to show that TLT-1 is selectively reduced in the platelets of patient 1, previously noted to be deficient in glycoprotein (GP)VI (Nurden et al, Blood 2004; 104:107−114). Yet both TLT-1 and GPVI were normally expressed in platelets of patient 2. Usual levels of JAM-C and claudin-5, also members of the immunoglobulin receptor family, were detected in platelets of both patients. In contrast, P-selectin was markedly decreased for patient 1 but not patient 2. Two metalloproteases, MMP-2 and MMP-9 were normally present. As predicted, platelets of patient 1 showed little labelling for TLT-1 in I-EM, whereas residual Fg was seen in small vesicular structures and P-selectin lining vacuoles or channels of what may be elements of the surface-connected canalicular system. Our results identify TLT-1 as a glycoprotein potentially targeted in platelets of GPS patients, while decreases in at least three membrane glycoproteins suggest that an unidentified proteolytic activity may contribute to the phenotype in some patients with this rare disease.

show abstract

Section: Discussionmentioning

confidence: 54%

Phenotypic heterogeneity in the gray platelet syndrome extends to the expression of TREM family member, TLT-1

Nurden¹,

Nurden²,

Bermejo³

et al. 2008

Thromb Haemost

View full text Add to dashboard Cite

show abstract

“…Microsomal fractions were isolated from rat brain, rat solid Morris hepatoma 3924A and human platelets by differential centrifugation as reported in refs. [32], [16] and [33] respectively.…”

Section: Preparation Of Microsomal Fractions and Permeabilized Plateletsmentioning

confidence: 99%

Physiological concentrations of inorganic phosphate affect MgATP-dependent Ca2+ Storage and inositol trisphosphate-induced Ca2+ efflux in microsomal vesicles from non-hepatic cells

Fulceri

Bellomo

Gamberucci

et al. 1993

Biochemical Journal

View full text Add to dashboard Cite

1. MgATP-dependent 45Ca2+ uptake by microsomes obtained from various non-hepatic tissues, namely rat brain, rat solid Morris hepatoma 3924A and human platelets, was measured in the presence of P(i) at low, cytosol-like, concentrations. 2. Increasing P(i) concentrations (0.5-3 mM) caused a progressive enlargement of the 45Ca(2+)-storage capacity of all the microsomal fractions. 3. As a result of P(i) stimulation of Ca2+ uptake, 45Ca2+ and [32P]P(i) were co-accumulated by the three microsomal fractions. 4. The time course for 45Ca2+ and [32P]P(i) accumulation in brain microsomes revealed a biphasic 45Ca2+ uptake: a rapid phase was followed by a second, slower, phase, which depended on the presence of P(i). During the P(i)-dependent phase, the uptake of 45Ca2+ was paralleled by the uptake of [32P]Pi. 5. The passive efflux of Ca2+ was paralleled by the efflux of P(i) and vice versa. In fact, the inhibition of active Ca2+ uptake by excess EGTA, or lowering the P(i) concentration of the incubation system by dilution, caused the release of 45Ca2+ and [32P]P(i) from 45Ca2+ or [32P]P(i) pre-loaded brain microsomes. The Ca2+ ionophore A23187 also released 45Ca2+ and [32P]P(i). 6. Ca2+ efflux by A23187 was rapid (t 1/2 approx. 2 s) and independent of the extent of intravesicular Ca2+ loading, which indicates that Ca2+ and P(i) do not form intravesicular insoluble complexes. 7. The progressive increase in Ca2+ accumulation, depending on P(i) stimulation, resulted in a proportional increase in the amount of Ca2+ releasable by InsP3 in the three non-hepatic microsomal fractions and in digitonin-permeabilized platelets. 8. Concomitantly to Ca2+, microsomal P(i) was also released by InsP3.

show abstract

“…Our previous investigations of the same patient (M.B.) showed an increase in Ca2+ transport into the microsomes isolated from her platelets, as well as a n increase in Caz+ATPase activity which mediated this transport (Enouf et al, 1987). Since these studies, progress has been made as regards the knowledge of the platelet CaL+ATPase system.…”

Section: Coniparative Ca2+atpusr Systems In Membrane Vesicles Isolatementioning

confidence: 86%

Abnormal cAMP‐induced phosphorylation of rap 1, protein in grey platelet syndrome platelets

et al. 1994

Self Cite

View full text Add to dashboard Cite

We previously demonstrated abnormal Ca2+ transport by microsomes in platelets from a grey platelet syndrome patient. Here, we investigated the platelet Ca2+ ATPases that mediate this transport, as well as its possible regulation by rap 1 protein. We showed that grey platelet syndrome platelets expressed the same two distinct Ca2+ ATPases as those recently described in normal platelets; the 100 kD SERCA2-b isoform (Sarco/Endoplasmic Reticulum Ca2+ATPase) and a new 97 kD SERCA isoform. The two Ca2+ATPases formed similar amounts of transient phosphorylated intermediates. The expression of these two Ca2+ATPases was compared by Western blotting using specific antibodies, which again emerged in similar amounts in normal and grey platelet syndrome platelets. As regards the protein phosphorylated by cAMP, it was found to be identical to rap 1 protein when it was immunoprecipitated with an antibody raised against a synthetic peptide specific for rap 1 protein. Although the expression of rap 1 protein was similar in membranes isolated from grey platelet syndrome and normal platelets, its exogenous phosphorylation by cAMP was abnormal, with a concentration (10 micrograms/ml) of the catalytic subunits of the cAMP-dependent protein kinase (C.Sub.), as it decreased to half the control level. It is concluded that the abnormal Ca2+ transport found in grey platelet syndrome platelets is not due to the abnormal expression of the Ca2+ATPases, but is associated with an abnormality of rap 1 protein phosphorylation by cAMP.

show abstract

Abnormal calcium transport into microsomes of grey platelet syndrome

Cited by 17 publications

References 15 publications

Phenotypic heterogeneity in the gray platelet syndrome extends to the expression of TREM family member, TLT-1

Phenotypic heterogeneity in the gray platelet syndrome extends to the expression of TREM family member, TLT-1

Physiological concentrations of inorganic phosphate affect MgATP-dependent Ca2+ Storage and inositol trisphosphate-induced Ca2+ efflux in microsomal vesicles from non-hepatic cells

Abnormal cAMP‐induced phosphorylation of rap 1, protein in grey platelet syndrome platelets

Contact Info

Product

Resources

About