| First Author | Kanaji T | Year | 2012 |
| Journal | Blood | Volume | 119 |
| Issue | 12 | Pages | 2906-13 |
| PubMed ID | 22174152 | Mgi Jnum | J:182455 |
| Mgi Id | MGI:5315658 | Doi | 10.1182/blood-2011-08-376566 |
| Citation | Kanaji T, et al. (2012) GPIbalpha regulates platelet size by controlling the subcellular localization of filamin. Blood 119(12):2906-13 |
| abstractText | Interaction between the cytoplasmic domain of GPIbalpha with its cytoskeletal binding partner, filamin, is a major determinant of platelet size, and deficiency of either protein results in macrothrombocytopenia. To clarify the mechanism by which GPIbalpha-filamin interactions regulate platelet production, we manipulated the expression levels of filamin and GPIb in cultured embryonic stem cells (ESCs) that were subsequently differentiated into platelets. Knocking down filamins A and B resulted in the production of ESC-derived proplatelets with abnormally large swellings and proplatelet shafts that generated giant platelets in culture. Large platelets could also be generated by overexpressing GPIbalpha in ESCs, or by overexpressing in vivo a transgene encoding a chimeric protein containing the cytoplasmic domain of GPIbalpha. To identify the mechanism by which the GPIb:filamin ratio regulates platelet size, we manipulated filamin and GPIbalpha levels in HEK293T cells and examined the effects of overexpressing either protein on their ability to traffic to the cell periphery. Accumulation of either protein within the endoplasmic reticulum resulted in trapping of the other. Taken together, these data demonstrate that coordinated expression of GPIbalpha and filamin is required for efficient trafficking of either protein to the cell surface, and for production of normal-sized platelets. |
