Fibrinogen selects selectins.

摘要

In this issue of Blood, Yang and colleagues provide new insights into how plasma fibrinogen, fibrinogen uptake, and integrin signaling regulate P-selectin in circulating platelets.' Iembrane P-selectin expression is considered one of the most reliable markers of murine and human platelet activation. Current dogma suggests that platelets are invested with an entire pool of P-selectin derived from parental megakaryocytes. In this regard, it is generally thought that megakaryocytes synthesize P-selectin and package it into alpha-granules that are subsequently sorted into platelets during throm-bopoiesis. Upon activation, megakaryocyte-derived P-selectin translocates to the plasma membrane of platelets where it serves as a tethering ligand that binds P-selectin glycoprotein-1 on target leukocytes, mediating adhesion and transmitting information.