SALAM SALLOUM ASFAR, ANA BELEN ARROYO RODRIGUEZ, RAÚL TERUEL MONTOYA, NURIA GARCÍA BARBERÁ, VANESSA ROLDAN SCHILLING, VICENTE VICENTE GARCÍA, CONSTANTINO MARTÍNEZ GÓMEZ, ROCÍO GONZÁLEZ-CONEJERO HILLA,

• [GI/IMIB/C001/2011] HEMATOLOGÍA Y ONCOLOGÍA MÉDICA CLÍNICO-EXPERIMENTAL

Coagulation factors have a substantial interindividual variability in healthy human plasma. MiRNAs have been reported as CIS-acting elements of several hemostatic factors, however, their mechanism as TRANS-acting elements mediated by a transcription factor is little known and could have important effects. A good candidate is the Hepatocyte Nuclear Factor 4? (HNF4?) that has a direct and important role in the regulation of multiple hepatic coagulation genes. Previous in vitro studies have demonstrated that miR-24-3p and miR-34a-5p regulate HNF4? expression. Here we aimed to thoroughly gain a deeper insight into the physiological modulator role of miR-24 and miR-34a in the expression of downstream coagulation targets of HNF4?.

We transfected HepG2 cells with miR-34a, miR-24, and a negative control. We measured the expression levels of F5, F8, F9, F11, F12, SERPINC1, PROC, and PROS1 by qRT-PCR. In human healthy livers (N=104), we analysed transcripts levels of the hemostatic proteins, as well as those of HNF4A, miR-34a, and miR-24.

Transfections with miR-24 and miR-34a in HepG2 cells decreased not only HNF4A but also F10, F12, SERPINC1, PROS1, PROC, and PROZ transcripts levels. Positive and significant correlations were observed between levels of HNF4A and several hemostatic factors (F5, F8, F9, F11, F12, SERPINC1, PROC, and PROS1) in human liver samples (N = 104). However, miR-24 and miR-34a levels of the low (10th) and high (90th) percentiles of those liver samples were inversely correlated with HNF4A and almost all hemostatic factors expression levels.

These outcomes results suggest that miR-24 and miR-34a might be two indirect elements of regulation of several hemostatic factors participating in the interindividual variability observed in their expression. Additionally, variations in miRNA expression profiles could justify, at least in part, changes in HNF4A expression levels and its downstream targets of coagulation. Therefore, in both circuits HNF4A would work as a key switchboard. It remains to be clarified to what extent genetic variations of miRNAs that change HNF4? expression and activity may affect the expression of hepatic coagulation factors, and to what extent this may affect the development of thrombotic or hemorrhagic disorders.