Research ArticlePhysiology

Mice Lacking the ITIM-Containing Receptor G6b-B Exhibit Macrothrombocytopenia and Aberrant Platelet Function

Science Signaling  30 Oct 2012:
Vol. 5, Issue 248, pp. ra78
DOI: 10.1126/scisignal.2002936

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Controlling Platelet Production

Megakaryocytes reside in the bone marrow, where they produce platelets, cell fragments that form clots to prevent blood loss at sites of damage to the vasculature. Platelets and megakaryocytes share many activating receptors on their surface, but unlike platelets, megakaryocytes fail to become activated when exposed to components of the extracellular matrix. Mazharian et al. found that mice deficient in the immunoreceptor tyrosine–based inhibition motif–containing receptor G6b-B had fewer and larger platelets than did their wild-type counterparts. In addition, G6b-B–deficient mice exhibited increased bleeding in response to damage and had activated megakaryocytes, which resulted in the production of defective platelets. Together, these data suggest that G6b-B dampens activating signals in megakaryocytes to enable the generation of the appropriate number of functional platelets.