Transgenic mice overexpressing Aurora-B/AIM-1. (A) Scheme of the PF4-Aurora-B/AIM-1 transgenic DNA construct. Not shown here is a short FLAG sequence engineered at the 5′ end of the cDNA, as detailed in “Materials and methods.” Rat Aurora-B/AIM-1 cDNA (indicated here as AIM-1) is under the control of the megakaryocyte-specific 1.1-kb rat PF4 promoter. The 3′ end of the gene was replaced with human β-globin genomic sequences. Restriction enzyme digestion sites are indicated: NdeI,B(BamHI), K (KpnI), and ApaI. (B) Southern blot analysis of genomic DNA extracted from mouse tails using radiolabeled rat Aurora-B/AIM-1 cDNA as a probe. DNA was digested with BamHI, yielding 2 fragments of 0.6 and 0.8 kb. The position of endogenous Aurora-B/AIM-1 is also indicated (mAIM-1). Transgene copy number (fold over endogenous Aurora-B/AIM-1 gene) ranged from 5 to 25. (C) Message level in total mouse bone marrow was monitored as described in “Materials and methods.” The cDNA was separated on 1% agarose gel, which was stained with ethidium bromide (EtBr) as shown. An evenly distributed appearance of bands is in accordance with our nonspecific PCR amplification of total cDNA derived from cells. Specific message level was detected by Southern blot analysis using radiolabeled Aurora-B/AIM-1, β-globin, or PF4 cDNAs, as detailed in “Materials and methods.” Shown are results from 1 of 3 representative experiments. In this study and in previous studies with PF4-driven genes, we noted reductions in PF4 mRNA in some of the lines. We do not believe this has an impact on megakaryopoiesis because the phenotype of these various models is typically different and because nonchallenged PF4 null mice have a level of CFU-Meg similar to that of wild-type mice.⁴⁴