Figure 1

Loss of Strumpellin results in decreased expression of the integrin αIIbβ3 in platelets and megakaryocytes. (a) Immunoblot analysis of Strumpellin, WASH, Fam21, CCDC53 and SWIP protein content in platelet lysates from control (Str^+/+) and Strumpellin-deficient (Str^−/−) mice (n = 3). Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) or α-tubulin served as loading control. (b) Platelet count and (c) size of peripheral blood platelets in control and Strumpellin-deficient mice measured by flow cytometry. Values are mean ± standard deviation (s.d.; n = 6). (d) Determination of the expression of αIIbβ3 on the surface of control and Strumpellin-deficient platelets with different antibodies recognizing the heterodimer αIIbβ3 (JON1, JON2, JON3, JON6 and MWReg30) or the β3 subunit (EDL1). Values are mean ± s.d. (n = 6; **P < 0.01;***P < 0.001). (e) Representative histogram of anti-αIIbβ3-FITC (MWReg30 and JON6) labeled platelet population from control (Str^+/+) and Strumpellin-deficient (Str^−/−) mice. (f) Ploidy level of primary BM MKs was assessed by flow cytometry. Values are mean ± s.d. (n = 5). (g) Surface expression of αIIbβ3 on primary BM MKs from all maturation stages (all N) and from MKs with ploidy greater than 4N (> 4N). Values are mean ± s.d. (n = 4; *P < 0.05). (h, i) Normalized fold mRNA expression of Itga2b (h) and Itgb3 (i) relative to MK specific mRNA Tubb1 from primary BM MKs based on qPCR. Values are mean ± s.d. (n = 4).