In drosophila, the preblastodermic syncytial nuclear divisions occur very fast. In this short period of time chromosomes must condense, segregate and decondense, in conditions governed by maternally provided RNAs and proteins. In this report, we show that the Homothorax (Hth) transcription factor is maternally provided and that its function is necessary for the proper assembly of the centric/centromeric heterochromatin during preblastodermic divisions. Embryos lacking the hth maternally-derived transcript, show abnormal localisation of the centromeric CID protein, and aberrant chromosomal segregation. In this syncytial context, Hth presumably acts together with its partner Extradenticle (Exd) and the RNA PolII, to facilitate transcription of satellite repeats. The transcripts derived from these sequences are needed for the correct assembly of the centric heterochromatin.
Homothorax belongs to the TALE-homeodomain family of transcription factors, together with its vertebrate counterparts, the Meis family of proto-oncogenes. It fulfills many important different functions during embryonic and larval developments in Drosophila, which encompass from subdivision and specification of body parts to assembly of heterochromatin structures. Hth interacts with Extradenticle, another member of the TALE-homeodomain family of conserved transcription factors, to facilitate its entrance to the nucleus. The many different functions described for Hth rely on the complexity of the locus, from which six different isoforms arise. The isoforms can be grouped into full-length and short versions, which contain either one or the two conserved domains of the protein (homeodomain and Exd-interacting domain). We have used molecular and genetic tools to analyze the levels of expression, the distribution and the function of the isoforms during embryonic development. Our results clearly show that the isoforms display distinct levels of expression and are differentially distributed in the embryo. This detailed study also shows that during normal embryonic development not all the Hth isoforms translocate Exd into the nucleus, suggesting that both the proteins can also function separately. We have demonstrated that the full-length Hth protein activates transcription of exd, augmenting the levels of exd mRNA in the cell. The higher levels of Exd protein in those cells facilitate its entrance to the nucleus. Our work demonstrates that hth is a complex gene that should not be considered as a functional unit. The roles of the different isoforms probably rely on their distinct protein domains and conformations and, at the end, on interactions with particular partners.
Aim To estimate the cost effectiveness and cost utility ratios of a restrictive vs liberal transfusion strategy in acute myocardial infarction (AMI) patients with anemia. Methods and Results Patients (n = 666) with AMI and hemoglobin between 7-8 and 10 g/dL recruited in 35 hospitals in France and Spain were randomly assigned to a restrictive (n = 342) or a liberal (n = 324) transfusion strategy with 1-year prospective collection of resource utilization and quality of life using the EQ5D3L questionnaire. The economic evaluation was based upon 648 patients from the per-protocol population. The outcomes were 30-day and 1-year cost-effectiveness, with major adverse cardiovascular event averted (MACE) as the effectiveness outcome; and 1-year cost utility ratio. The 30-day incremental cost-effectiveness ratio was €33,065€ saved per additional MACE averted with the restrictive versus the liberal strategy, with an 84% probability for the restrictive strategy to be cost-saving and MACE reducing (i.e.dominant). At 1-year, the point estimate of the cost-utility ratio was 191,500 € saved per QALY gained; however cumulated MACE were outside the pre-specified non-inferiority margin, resulting in a decremental cost effectiveness ratio with a point estimate of €72,000 saved per additional MACE with the restrictive strategy. Conclusion In patients with acute myocardial infarction and anemia, the restrictive transfusion strategy was dominant (cost-saving and outcome-improving) at 30 days. At 1 year, the restrictive strategy remained cost-saving but clinical noninferiority on MACE was no longer maintained. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT02648113.
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