RT Journal Article SR Electronic T1 Immunosuppressor FK506 Increases Endoglin and Activin Receptor-Like Kinase 1 Expression and Modulates Transforming Growth Factor-β1 Signaling in Endothelial Cells JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 833 OP 843 DO 10.1124/mol.110.067447 VO 79 IS 5 A1 Albiñana, Virginia A1 Sanz-Rodríguez, Francisco A1 Recio-Poveda, Lucía A1 Bernabéu, Carmelo A1 Botella, Luisa M. YR 2011 UL http://molpharm.aspetjournals.org/content/79/5/833.abstract AB Hereditary hemorrhagic telangiectasia (HHT), or Rendu-Osler-Weber syndrome, is an autosomal-dominant vascular disease. The clinical manifestations are epistaxis, mucocutaneous and gastrointestinal telangiectases, and arteriovenous malformations in internal organs. Patients show severe epistaxis, and/or gastrointestinal bleeding, both of which notably interfere with their quality of life. There are two predominant types of HHT caused by mutations in endoglin (ENG) and ACVRL1/activin receptor-like kinase 1 (ALK1) genes, named HHT1 and HHT2, respectively. ENG and ALK1 code for proteins involved in the transforming growth factor (TGF)-β1 signaling pathway, and it is widely accepted that HHT pathogenicity results from haploinsufficiency. No cure for HHT has been found, so identification of drugs able to increase the expression of these genes is essential when proposing new therapies. We report the efficacy of tacrolimus (FK506) in increasing ENG and ALK1 expression. The rationale comes from a case report of a patient with HHT who received a liver transplantation after hepatic failure due to a liver arteriovenous malformation. The liver was transplanted, and the immunosuppressor FK506 was used to prevent the rejection. After the first month of FK506 treatment, the internal and external telangiectases, epistaxes, and anemia disappeared. Here, we find that the immunosuppressor FK506 increases the protein and mRNA expression of ENG and ALK1 in cultured endothelial cells and enhances the TGF-β1/ALK1 signaling pathway and endothelial cell functions like tubulogenesis and migration. These results suggest that the mechanism of action of FK506 involves a partial correction of endoglin and ALK1 haploinsufficiency and may therefore be an interesting drug for use in patients with HHT who undergo transplantation.