Platelets possess three P2 receptors: two (P2Y1 and P2Y 12) are receptors for adenosine diphosphate (ADP), and one (P2X1) is a receptor for adenosine triphosphate (ATP). The P2Y1 receptor, which is coupled to Gq and phospholipase C-(beta), is responsible for mobilization of ionized calcium from internal stores and mediates the ADP-induced platelet shape change and initial wave of rapidly reversible aggregation. The other ADP receptor, P2Y12, is negatively coupled to adenylyl cyclase through Gi and mediates a progressive and sustained ADP-induced aggregation not preceded by shape change. In addition, this receptor plays an important role in the potentiation of platelet secretion induced by several platelet agonists. The combined action of P2Y1 and P2Y12 is necessary for the full platelet aggregation response to ADP. Four patients with severe deficiency of P2Y12 have been described so far. Sequence analysis of the P2Y12 locus of three of these patients revealed homozygous mutations that produced a frame shift mutation and premature truncation of the protein. The fourth patient had an allele with a frame shift mutation and a normal allele, which could be silenced by an additional, as yet unknown, mutation. More recently, we described a patient with a congenital bleeding disorder and a dysfunctional P2Y12. The patient is a compound heterozygote, in whom one allele contained a G to A transition resulting in an Arg256 to Gln codon substitution (R256Q) and the other allele contained a C to T transition resulting in an Arg265 to Trp codon substitution (R265W). The two substitutions are located in TM6 and EL3 of the receptor. Stable Chinese hamster ovaries (CHO) cell lines were established expressing either wildtype P2Y12 and P2Y12R256Q or P2Y12R265W. Neither mutation blocked the ability of the P2Y12 receptor to translocate to the CHO cell surface. ADP at all tested concentrations (0.1 to 10 (mu)M) greatly inhibited the forskolin-induced increase of cyclic adenosine monophosphate (cAMP) in CHO cells transfected with wild-type P2Y12, whereas CHO cells transfected with either mutant protein were only partially inhibited by ADP. Thus, the molecular basis for the patient's dysfunctional platelet phenotype is explained by missense mutations and the expression of a dysfunctional P2Y12 receptor. The localization of both mutations in TM6 and EL3 identifies this region of P2Y 12 as a structurally and functionally critical region of the receptor

The P2 receptors and congenital platelet function defects / M. Cattaneo. - In: SEMINARS IN THROMBOSIS AND HEMOSTASIS. - ISSN 0094-6176. - 32:1(2006 Jan), pp. 77-78.

The P2 receptors and congenital platelet function defects

M. Cattaneo
Primo
2006

Abstract

Platelets possess three P2 receptors: two (P2Y1 and P2Y 12) are receptors for adenosine diphosphate (ADP), and one (P2X1) is a receptor for adenosine triphosphate (ATP). The P2Y1 receptor, which is coupled to Gq and phospholipase C-(beta), is responsible for mobilization of ionized calcium from internal stores and mediates the ADP-induced platelet shape change and initial wave of rapidly reversible aggregation. The other ADP receptor, P2Y12, is negatively coupled to adenylyl cyclase through Gi and mediates a progressive and sustained ADP-induced aggregation not preceded by shape change. In addition, this receptor plays an important role in the potentiation of platelet secretion induced by several platelet agonists. The combined action of P2Y1 and P2Y12 is necessary for the full platelet aggregation response to ADP. Four patients with severe deficiency of P2Y12 have been described so far. Sequence analysis of the P2Y12 locus of three of these patients revealed homozygous mutations that produced a frame shift mutation and premature truncation of the protein. The fourth patient had an allele with a frame shift mutation and a normal allele, which could be silenced by an additional, as yet unknown, mutation. More recently, we described a patient with a congenital bleeding disorder and a dysfunctional P2Y12. The patient is a compound heterozygote, in whom one allele contained a G to A transition resulting in an Arg256 to Gln codon substitution (R256Q) and the other allele contained a C to T transition resulting in an Arg265 to Trp codon substitution (R265W). The two substitutions are located in TM6 and EL3 of the receptor. Stable Chinese hamster ovaries (CHO) cell lines were established expressing either wildtype P2Y12 and P2Y12R256Q or P2Y12R265W. Neither mutation blocked the ability of the P2Y12 receptor to translocate to the CHO cell surface. ADP at all tested concentrations (0.1 to 10 (mu)M) greatly inhibited the forskolin-induced increase of cyclic adenosine monophosphate (cAMP) in CHO cells transfected with wild-type P2Y12, whereas CHO cells transfected with either mutant protein were only partially inhibited by ADP. Thus, the molecular basis for the patient's dysfunctional platelet phenotype is explained by missense mutations and the expression of a dysfunctional P2Y12 receptor. The localization of both mutations in TM6 and EL3 identifies this region of P2Y 12 as a structurally and functionally critical region of the receptor
CHO cell ; Adult ; Allele ; Amino acid substitution ; Animal cell ; Calcium mobilization ; Case report ; Congenital blood clotting disorder ; Female ; Frameshift mutation ; Gene location ; Gene locus ; Genetic transfection ; Homozygosity ; human ; Male ; Missense mutation ; Nonhuman ; Phenotype ; Priority journal ; Protein expression ; Protein structure ; Review ; Sequence analysis ; Thrombocyte aggregation ; Thrombocyte anomaly ; Thrombocyte shape ; Adenine ; Adenosine diphosphate ; Adenosine triphosphate ; Adenylate cyclase ; Arginine ; Cyclic AMP ; Cytosine ; Desmopressin ; Glutamine ; Mutant protein ; Phospholipase C ; Phospholipase c beta ; Purine P2 receptor ; Purine P2X1 receptor ; Purine P2Y1 receptor ; Purine P2Y12 receptor ; Thymine ; Unclassified drug ; Vasopressin derivative
Settore MED/09 - Medicina Interna
gen-2006
Article (author)
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/30680
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 1
  • ???jsp.display-item.citation.isi??? ND
social impact